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Posts Tagged ‘Estrogen’


Reporter and Curator: Dr. Sudipta Saha, Ph.D.

 

During menopause a woman’s ovaries stop working—leading to hot flashes, sleep problems, weight gain, and worse, bone deterioration. Now scientists are exploring whether transplanting lab-made ovaries might stop those symptoms. In one of the first efforts to explore the potential of such a technique, researchers say they used tissue engineering to construct artificial rat ovaries able to supply female hormones like estrogen and progesterone. A research carried out at Wake Forest Baptist Medical Center, suggests a potential alternative to the synthetic hormones millions of women take after reaching middle age. A paper describing the findings was published in Nature Communications.

 

Women going through menopause, as well as those who have undergone cancer treatment or had their ovaries removed for medical purposes, lose the ability to produce important hormones, including estrogen and progesterone. Lower levels of these hormones can affect a number of different body functions. To counteract unpleasant symptoms, many women turn to combinations of hormone replacement medications—synthetic estrogen and progestin. Pharmacologic hormone replacement therapy (pHRT) with estrogen alone or estrogen and progestogens is known to effectively ameliorate the unpleasant symptoms. But hormone replacement carries an increased risk of heart disease and breast cancer, so it’s not recommended for long-term use. In these circumstances artificial ovaries could be safer and more effective.

 

Regenerative medicine approaches that use cell-based hormone replacement therapy (cHRT) offer a potential solution to temporal control of hormone delivery and the ability to restore the HPO (Hypothalamo-Pituitary-Ovarian) axis in a way not possible with pHRT. Scientists have previously described an approach to achieve microencapsulation of ovarian cells that results in bioengineered constructs that replicate key structure-function relationships of ovarian follicles as an approach to cHRT. In the present study the scientists have adapted an isogeneic cell-based construct to provide a proof-of-concept for the potential benefits of cHRT.

 

Tissue or cell encapsulation may offer effective strategies to fabricate ovarian constructs for the purpose of fertility and/or hormone replacement. Approaches using segmental ovarian tissue or whole-follicle implantation (typically with a focus on cryopreservation of the tissue for reproductive purposes) have resulted in detectable hormone levels in the blood after transplantation. Previous studies have also shown that autotransplantation of frozen-thawed ovarian tissue can lead to hormone secretion for over 5 years in humans.

 

Although these approaches can be used to achieve the dual purpose of fertility and hormone replacement in premenopausal women undergoing premature ovarian failure, they would have limited application in postmenopausal women who only need hormone replacement to manage menopausal symptoms and in whom fertility is not desirable. In full development, the technology described in this research is focused on hormone replacement, would meet the needs of the latter group of women that is the postmenopausal women.

 

The cell-based system of hormone replacement described in this report offers an attractive alternative to traditional pharmacological approaches and is consistent with current guidelines in the U.S. and Europe recommending the lowest possible doses of hormone for replacement therapy. In the present research sustained stable hormone release over the course of 90 days of study was demonstrated. The study also demonstrated the effective end-organ outcomes in body fat composition, uterine health, and bone health. However, additional studies will be required to determine the sustainability of the hormone secretion of the constructs by measuring hormone levels from implanted constructs for periods longer than 3 months in the rat model.

 

This study highlights the potential utility of cHRT for the treatment and study of conditions associated with functional loss of the ovaries. Although longer-term studies would be of future interest, the 90-day duration of this rodent model study is consistent with others investigating osteoporosis in an ovariectomy model. However, this study provides a proof-of-concept for cHRT, it suffers the limitation that it is only an isogeneic-based construct implantation. Scientists think that further studies in either allogeneic or xenogeneic settings would be required with the construct design described in this report in the path towards clinical translation given that patients who would receive this type of treatment are unlikely to have sufficient autologous ovarian cells for transplantation.

 

References:

 

https://www.technologyreview.com/the-download/609677/will-artificial-ovaries-mean-no-more-menopause/

 

https://www.nature.com/articles/s41467-017-01851-3

 

https://www.ncbi.nlm.nih.gov/pubmed/23274068

 

https://www.ncbi.nlm.nih.gov/pubmed/26210678

 

https://www.ncbi.nlm.nih.gov/pubmed/21954279

 

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New Estrogen without Breast Proliferation Effect

Curator: Larry H. Bernstein, MD, FCAP

LPBI

 

NEW ESTROGENS MAY HAVE BENEFICIAL EFFECTS WITHOUT INCREASING CANCER RISK – JUNE 4, 2016

Written By: Dr. Fanni R. Eros

New Estrogens May Have Beneficial Effects Without Increasing Cancer Risk – June 4, 2016

An American research group designed a new estrogen molecule, PaPE-1, and found that PaPE-1 might have beneficial effects on metabolism and vascular health, while not enhancing proliferation in uterine and breast cells, therefore not increasing cancer risk.

 

After menopause, estrogen therapy is proved to help prevent metabolic and vascular diseases. However, estrogen (a female sex hormone) also has proliferative effects on the uterus and breasts, increasing cancer risk. Estrogens operate through two pathways: the nuclear-initiated and extranuclear-initiated pathways. The extranuclear-initiated pathway is responsible for the beneficial effects of estrogens, while activation of the nuclear-initiated pathway may result in adverse effects, such as cell proliferation of the uterus and breasts. It seems that estrogen molecules that bind to estrogen receptors (ER) with high affinity activate both pathways, while an estrogen molecule with a low-affinity binding capability can only activate the extranuclear-initiated pathway, and therefore have only beneficial effects.

In an article recently published in Science Signalling, an American research group investigated the effects of pathway preferential estrogens (PaPEs) compared to estradiol (E2, a form of estrogen and a common supplement for post-menopausal women). They altered the structure of E2 which reduced the binding affinity of the new molecule (PaPE-1) by 50000 times compared to E2, but could still form a competent complex with the receptor. They found that PaPE-1 was selective in activating the extranuclear-initiated pathway and it did not stimulate proliferation of human breast cancer cells, but activated the mTOR pathway that modulates metabolic functions. Both E2 and PaPE-1 treatment resulted in increased gene expression, however E2 activated more genes overall and more genes related to cell proliferation.

To test the new molecule in vivo, researchers used ovariectomized female mice (mice with ovaries removed) and treated them with a control vehicle, E2, or PaPE-1. Compared to E2, PaPE-1 did not have any effect on uterine weight, mammary ductal growth and thymus size. However, both E2 and PaPE-1 reduced the mammary gland fat deposits that developed after ovariectomy and they both decreased body weight. Both hormones reduced fat mass, triglyceride (fat) concentrations in blood and liver lipid content, but only E2 increased total lean mass and water mass.
Investigators further examined the gene expression and found that both PaPE-1 and E2 induced gene expression changes in liver and skeletal muscles, while only E2 altered the gene expression in the uterus.

When researchers used mice that had no α-type ER, E2 did not stimulate uterine growth and neither PaPE-1 nor E2 decreased blood triglycerides.
Researchers also investigated the beneficial vascular effects of E2 and PaPE-1 compared to the control vehicle. They treated mice with one of the three substances, injured their carotid artery and then continued the therapy for 3 more days. They found that both E2 and PaPE-1 treatment caused similar vascular repair and that the effect could be prevented by administering anti-estrogens.
The research group designed 3 more molecules, PaPE-2, 3 and 4, that also activated the extranuclear-initiated pathway and therefore showed similar tissue-selective effects.

After menopause, estrogen supplementation can have beneficial cardiovascular and metabolic effects. However, estrogen therapy may result in proliferation of uterine and breast cells and it increases uterus and breast cancer risk. PaPE-1 seems to be an estrogen molecule that combines all the beneficial effects of estrogen supplementation without increasing cancer risk. Furthermore, the process used to develop these new molecules can be applied to other hormones, such as glucocorticoids and Vitamin D, which may result in drugs with more selective activity.

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Sex Hormones

Author: Larry H Bernstein, MD, FCAP

A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be
grouped into five groups by the receptors to which they bind:

  • glucocorticoids,
  • mineralocorticoids,
  • androgens,
  • estrogens, and
  • progestogens.
  • Vitamin D derivatives, are a sixth closely related hormone system with homologous receptors. They have some of the characteristics of true steroids as receptor ligands.

Steroid hormones help control metabolism, inflammation, immune functions, salt
and water balance, development of sexual characteristics, and the ability to withstand
illness and injury. The term steroid describes both hormones produced by the body
and artificially produced medications that duplicate the action for the naturally occurring steroids

The natural steroid hormones are generally synthesized from cholesterol in the gonads and adrenal glands. These forms of hormones are lipids. They can pass through the cell membrane as they are fat-soluble,[4] and then bind to steroid hormone receptors (which may be nuclear or cytosolic depending on the steroid hormone) to bring about changes within the cell. Steroid hormones are generally carried in the blood, bound to specific carrier proteins such as sex hormone-binding globulin or corticosteroid-binding globulin. Further conversions and catabolism
occurs in the liver, in other “peripheral” tissues, and in the target tissues.

Synthetic steroids and sterols

A variety of synthetic steroids and sterols have also been contrived. Most are
steroids, but some non-steroidal molecules can interact with the steroid receptors
because of a similarity of shape. Some synthetic steroids are weaker or stronger
than the natural steroids whose receptors they activate.

Some examples of synthetic steroid hormones:
Glucocorticoids: alclometasone, prednisone, dexamethasone, triamcinolone
Mineralocorticoid: fludrocortisone
Vitamin D: dihydrotachysterol
Androgens: apoptone, oxandrolone, oxabolone, testosterone, nandrolone (also
known as anabolic steroids)
Estrogens: diethylstilbestrol (DES)
Progestins: danazol, norethindrone, medroxyprogesterone acetate,
17-Hydroxyprogesterone caproate.

Some steroid antagonists:
Androgen: cyproterone acetate
Progestins: mifepristone, gestrinone
http://www.en.wikipedia.org/wiki/Steroid

Steroid-Hormone-Synthesis

Steroid-Hormone-Synthesis

Steroidogenesis

Steroidogenesis


http://www.gfmer.ch/Books/Reproductive_health/Image171.gif

The regulation of spermatogenesis by androgens

Lee B. Smith, William H. Walker
Seminars in Cell & Developmental Biology 30 (2014) 2–13
http://dx.doi.org/10.1016/j.semcdb.2014.02.012

Testosterone is essential for maintaining spermatogenesis and male fertility.
However, the molecular mechanisms by which testosterone acts have not
begun to be revealed until recently. With the advances obtained from the use
of transgenic mice lacking or overexpressing the androgen receptor, the cell
specific targets of testosterone action as well as the genes and signaling pathways
that are regulated by testosterone are being identified. In this review, the critical
steps of spermatogenesis that are regulated by testosterone are discussed as well
as the intracellular signaling pathways by which testosterone acts. We also review
the functional information that has been obtained from the knock out of the androgen
receptor from specific cell types in the testis and the genes found to be regulated
after altering testosterone levels or androgen receptor expression.

The essence of female–male physiological dimorphism: Differential Ca2+-homeostasis
enabled by the interplay between farnesol-like endogenous sesquiterpenoids and
sex-steroids? The Calcigender paradigm

Arnold De Loof
General and Comparative Endocrinology 211 (2015) 131–146
http://dx.doi.org/10.1016/j.ygcen.2014.12.003

Ca2+ is the most omnipresent pollutant on earth, in higher concentrations a real
threat to all living cells. When [Ca2+]i rises above 100 nM (=resting level), excess
Ca2+ needs to be confined in the SER and mitochondria, or extruded by the different
Ca2+-ATPases. The evolutionary origin of eggs and sperm cells has a crucial, yet
often overlooked link with Ca2+-homeostasis. Because there is no goal whatsoever
in evolution, gametes did neither originate ‘‘with the purpose’’ of generating a progeny
nor of increasing fitness by introducing meiosis. The explanation may simply be that
females ‘‘invented the trick’’ to extrude eggs from their body as an escape strategy
for getting rid of toxic excess Ca2+ resulting from a sex-hormone driven increased
influx into particular cells and tissues.
The production of Ca2+-rich milk, seminal fluid in males and all secreted proteins
by eukaryotic cells may be similarly explained. This view necessitates an upgrade
of the role of the RER-Golgi system in extruding Ca2+. In the context of insect
metamorphosis, it has recently been (re)discovered that (some isoforms of) Ca2+-
ATPases act as membrane receptors for some types of lipophilic ligands, in
particular for endogenous farnesol-like sesquiterpenoids (FLS) and, perhaps, for
some steroid hormones as well.
A novel paradigm, tentatively named ‘‘Calcigender’’ emerges. Its essence is: gender-
specific physiotypes ensue from differential Ca2+-homeostasis enabled by genetic
differences, farnesol/FLS and sex hormones. Apparently the body of reproducing
females gets temporarily more poisoned by Ca2+ than the male one, a selective
benefit rather than a disadvantage.

Sex differences in the expression of estrogen receptor alpha within noradrenergic
neurons in the sheep brain stem

J.L. Rose, A.S. Hamlin, C.J. Scott
Domestic Animal Endocrinology 49 (2014) 6–13
http://dx.doi.org/10.1016/j.domaniend.2014.04.003

In female sheep, high levels of estrogen exert a positive feedback action
on gonadotropin releasing hormone (GnRH) secretion to stimulate a surge in
luteinizing hormone (LH) secretion. Part of this action appears to be via brain
stem noradrenergic neurons. By contrast, estrogen action in male sheep has
a negative feedback action to inhibit GnRH and LH secretion. To investigate
whether part of this sex difference is due to differences in estrogen action in
the brain stem, we tested the hypothesis that the distribution of estrogen
receptor a (ERα) within noradrenergic neurons in the brain stem differs
between rams and ewes. To determine the distribution of ERα, we used
double-label fluorescence immunohistochemistry for dopamine b-Hydroxylase,
as a marker for noradrenergic and adrenergic cells, and ERα. In the ventro-
lateral medulla (A1 region), most ERα-immunoreactive (-ir) cells were
located in the caudal part of the nucleus. Overall, there were more ERα-ir
cells in rams than ewes, but the proportion of double-labeled cells was did
not differ between sexes. Much greater numbers of ERα–ir cells were
found in the nucleus of the solitary tract (A2 region), but <10% were double
labeled and there were no sex differences. The majority of ERα-labeled cells
in this nucleus was located in the more rostral areas. Erα labeled cells were
found in several rostral brain stem regions but none of these were double
labeled and so were not quantified. Because there was no sex difference
in the number of ERα-ir cells in the brain stem that were noradrenergic,
the sex difference in the action of estrogen on gonadotropin secretion in
sheep is unlikely to involve actions on brain stem noradrenergic cells.

Androgens, estrogens, and second messengers

William Rosner, DJ Hryb, MS Khan, AM Nakhla, and NA Romas
Steroids 1998; 63:278 –281 PII S0039-128X(98)00017-8

Over the course of the last four decades, a detailed understanding of the
molecular mechanisms by which steroid hormones exert their effects has
evolved, and continues to evolve. The major focus of research in this area
has been on the manner in which steroid receptors activate transcription.
Pathways of steroid action other than by direct interaction with intracellular
receptors have received relatively little attention. However, there is a growing
body of evidence that steroid hormones exert effects through mechanisms
in addition to those involving their classic intracellular receptors. One such
mechanism is based on the observation that a number of cells have receptors
on their plasma membranes for the plasma protein, sex hormone binding
globulin (SHBG). It is the purpose of this review to briefly describe our current
knowledge of this system.

SHBG binds to a receptor (RSHBG) on cell membranes cAMP and the steroid-SHBG-RSHBG system
Biology of the SHBG-RSHBG system

Relation between the affinity of steroid for SHBG and its potency in inhibiting
the binding of SHBG to RSHBG.

KA (SHBG) = Association constant for SHBG and the indicated steroid.
Ki SHBG-RSHBG = The inhibition constant for the indicated steroid on the
binding of SHBG to RSHBG.

PSA secretion was stimulated by DHT. Although estradiol alone had no effect
on PSA secretion, it caused an increase equal to that seen with DHT if the
prostate tissue was first loaded with SHBG, e.g., if RSHBG was occupied by
SHBG. Because estradiol-SHBG increases intracellular cAMP, we ascertained
whether other compounds that raise cAMP (forskolin), or cAMP itself, could
increase PSA secretion. Such was the case. cAMP begins its signal cascade
by activating protein kinase A (PKA) so that if estradiol-SHBG increases PSA
secretion by a mechanism involving cAMP, inhibition of PKA should block
estradiol-SHBG-initiated PSA secretion. Estradiol-SHBG failed to stimulate
PSA when PKA was inhibited with PKI. On the other hand, DHT-stimulated
PSA secretion, which does not involve PKA, was not inhibited by PKI. That
the effect of estradiol-SHBG was independent of the estrogen receptor was
shown by the lack of inhibition of estrogen-stimulated PSA secretion by two
anti-estrogens, tamoxifen and ICI 164,284. The promoter of the PSA gene
has an androgen response element, and both PSA secretion and the
expression of PSA mRNA are androgen-regulated. We investigated the
effect of hydroxyflutamide and cyproterone acetate. Both potent anti-
androgens, on the E2-SHBG-mediated increase in PSA secretion. secretion.
They also blocked the effect of E2-SHBG on PSA secretion. Since E2 is
not exerting its effect by binding to the AR, e.g., it is not its cognate ligand,
the E2-induced secretion of PSA observed in this study reflects ligand-
independent activation of the AR.26 Thus, estradiol activates a typical
AR-mediated event, PSA synthesis and secretion, by activating SHBG-
RSHBG. These data make clear the fact that there is cross-talk between a
steroid hormone-engendered event at the cell membrane and a classic
intracellular steroid hormone receptor.
Abbreviations: PSA, prostate specific antigen; DHT, dihydrotestosterone;
E2, estradiol; PKI, inhibitor of protein kinase A; ICI 164,384 (a pure anti-
estrogen); 2MeOE2, 2 methoxyestradiol; Cypro, cyproterone acetate,
OHFlut, hydroxyflutamide.

Role of G protein-coupled estrogen receptor 1, GPER, in inhibition of oocyte
maturation by endogenous estrogens in zebrafish

Yefei Pang, Peter Thomas
Developmental Biology 342 (2010) 194–206
http://dx.doi.org:/10.1016/j.ydbio.2010.03.027

Estrogen inhibition of oocyte maturation (OM) and the role of GPER (formerly
known as GPR30) were investigated in zebrafish. Estradiol-17β (E2) and G-1,
a GPER-selective agonist, bound to zebrafish oocyte membranes suggesting
the presence of GPER which was confirmed by immunocytochemistry using
a specific GPER antibody. Incubation of follicle-enclosed oocytes with an
aromatase inhibitor, ATD, and enzymatic and manual removal of the ovarian
follicle cell layers significantly increased spontaneous OM which was partially
reversed by co-treatment with either 100 nM E2 or G-1. Incubation of
denuded oocytes with the GPER antibody blocked the inhibitory effects of
estrogens on OM, whereas microinjection of estrogen receptor alpha (ERα)
antisense oligonucleotides into the oocytes was ineffective. The results
suggest that endogenous estrogens produced by the follicle cells inhibit or
delay spontaneous maturation of zebrafish oocytes and that this estrogen
action is mediated through GPER. Treatment with E2 and G-1 also attenuated
the stimulatory effect of the teleost maturation-inducing steroid, 17,20 β-
dihyroxy-4-pregnen-3-one (DHP), on OM.  Moreover, E2 and G-1 down-
regulated the expression of membrane progestin receptor alpha (mPRα),
the intermediary in DHP induction of OM. Conversely DHP treatment caused
a N50% decline in GPER mRNA levels. The results suggest that estrogens
and GPER are critical components of the endocrine system controlling
the onset of OM in zebrafish. A model is proposed for the dual control of the
onset of oocyte maturation in teleosts by estrogens and progestins acting
through GPER and mPRα, respectively, at different stages of oocyte
development.
Reprint of ’’GPR30 mediates estrogen rapid signaling and neuroprotection’’

Hui Tang, Q Zhang, L Yang, Y Dong, M Khan, F Yang, DW Brann, R Wang
Molecular and Cellular Endocrinology 389 (2014) 92–98
http://dx.doi.org/10.1016/j.mce.2014.01.024
http://dx.doi.org/10.1016/j.mce.2014.05.005

G-protein-coupled estrogen receptor-30 (GPR30), also known as G-protein
estrogen receptor-1 (GPER1), is a putative extranuclear estrogen receptor
whose precise functions in the brain are poorly understood. Studies using
exogenous administration of the GPR30 agonist, G1 suggests that GPR30
may have a neuroprotective role in cerebral ischemia. However, the
physiological role of GPR30 in mediating estrogen (E2)-induced neuro-
protection in cerebral ischemia remains unclear. Also unclear is whether
GPR30 has a role in mediating rapid signaling by E2 after cerebral ischemia,
which is thought to underlie its neuroprotective actions. To address these
deficits in our knowledge, the current study examined the effect of antisense
oligonucleotide (AS) knockdown of GPR30 in the hippocampal CA1 region
upon E2-BSA induced neuroprotection and rapid kinase signaling in a rat
model of global cerebral ischemia (GCI). Immunohistochemistry demonstrated
that GPR30 is strongly expressed in the hippocampal CA1 region and
dentate gyrus, with less expression in the CA3 region. E2-BSA exerted
robust neuroprotection of hippocampal CA1 neurons against GCI, an effect
abrogated by AS knockdown of GPR30. Missense control oligonucleotides had
no effect upon E2-BSA-induced neuroprotection, indicating specificity of the
effect. The GPR30 agonist, G1 also exerted significant neuroprotection against
GCI. E2-BSA and G1 also rapidly enhanced activation of the prosurvival
kinases, Akt and ERK, while decreasing proapototic JNK activation. Importantly,
AS knockdown of GPR30 markedly attenuated these rapid kinase signaling
effects of E2-BSA. As a whole, the studies provide evidence of an important
role of GPR30 in mediating the rapid signaling and neuroprotective actions
of E2 in the hippocampus.
Regulation of brain microglia by female gonadal steroids

Pardes Habib, Cordian Beyer
Journal of Steroid Biochemistry & Molecular Biology 2015; 146: 3–14
http://dx.doi.org/10.1016/j.jsbmb.2014.02.018

Microglial cells are the primary mediators of the CNS immune defense system
and crucial for shaping inflammatory responses. They represent a highly
dynamic cell population which is constantly moving and surveying their
environment. Acute brain damage causes a local attraction and activation of
this  immune cell type which involves neuron-to-glia and glia-to-glia interactions.
The prevailing view attributes microglia a “negative” role such as defense and
debris elimination. More topical studies also suggest a protective and “positive”
regulatory function. Estrogens and progestins exert anti-inflammatory and
neuroprotective effects in the CNS in acute and chronic brain diseases.
Recent work revealed that microglial cells express subsets of classical and
non-classical estrogen and progesterone receptors in a highly dynamic way.
In this review article, we would like to stress the importance of microglia for
the spreading of neural damage during hypoxia, their susceptibility to functional
modulation by sex steroids, the potency of sex hormones to switch microglia
from a pro-inflammatory M1 to neuroprotective M2 phenotype, and the
regulation of pro-and anti-inflammatory properties including the inflammasome.
We will further discuss the possibility that the neuroprotective action of sex
steroids in the brain involves an early and direct modulation of local microglia
cell function. Neuroprotection by gonadal steroid hormones in acute brain
damage requires cooperation with astroglia and microglia

Sonja Johann, Cordian Beyer
http://dx.doi.org/10.1016/j.jsbmb.2012.11.006

The neuroactive steroids 17β-estradiol and progesterone control a broad
spectrum of neural functions. Besides their roles in the regulation of classical
neuroendocrine loops, they strongly influence motor and cognitive systems,
behavior, and modulate brain performance at almost every level. Such a
statement is underpinned by the widespread and lifelong expression pattern
of all types of classical and non-classical estrogen and progesterone receptors
in the CNS. The life-sustaining power of neurosteroids for tattered or seriously
damaged neurons aroused interest in the scientific community in the past years
to study their ability for therapeutic use under neuropathological challenges.
Documented by excellent studies either performed in vitro or in adequate animal
models mimicking acute toxic or chronic neuro-degenerative brain disorders,
both hormones revealed a high potency to protect neurons from damage
and saved neural systems from collapse. Unfortunately, neurons, astroglia,
microglia, and oligodendrocytes are comparably target cells for both steroid
hormones. This hampers the precise assignment and understanding of
neuroprotective cellular mechanisms activated by both steroids. In this article,
we strive for a better comprehension of the mutual reaction between these
steroid hormones and the two major glial cell types involved in the maintenance
of brain homeostasis, astroglia and microglia, during acute traumatic brain
injuries such as stroke and hypoxia. In particular, we attempt to summarize
steroid-activated cellular signaling pathways and molecular responses in these
cells and their contribution to dampening neuroinflammation and neural
destruction.

Photoperiod influences the ontogenetic expression of aromatase
and estrogen receptor α in the developing tilapia brain.

Li-Hsueh Wang, Ching-Lin Tsai
General and Comparative Endocrinology 2006; 145: 62–66
http://dx.doi.org:/10.1016/j.ygcen.2005.07.004

Neural development is determined not only by genetic regulation, but also
by environmental cues. Central estrogen-forming/estrogen-sensitive systems
play an important role in the neural development of the brain. In the present
study, the quantitative reverse transcription-polymerase chain reaction method
was used to investigate the effects of photoperiod on the ontogenetic
expression of aromatase and estrogen receptor a (ERα) in the developing
tilapia brain. Before day 5 post-hatch, brain aromatase mRNA expression was
significantly decreased by constant light but not influenced by constant darkness.
During this period, brain ERα mRNA expression was significantly increased
under both constant light and constant darkness. Between days 5 and 10, and
between days 10 and 15, neither brain aromatase nor brain ERα expression
was altered under constant darkness and constant light. These results indicate
that the ontogenetic expression of brain aromatase and brain ERα is not via a
light-inducing process but influenced by a light-entraining signal during the
very early period of development.

Orphanin FQ-ORL-1 Regulation of Reproduction and Reproductive Behavior in
the Female

Kevin Sinchak, Lauren Dalhousay, Nayna Sanathara
Vitamins and Hormones 187-220.  http://dx.doi.org/10.1016/bs.vh.2014.11.002

Orphanin FQ (OFQ/N) and its receptor, opioid receptor-like receptor-1 (ORL-1),
are expressed throughout steroid-responsive limbic and hypothalamic circuits
that regulate female ovarian hormone feedback and reproductive behavior
circuits. The arcuate nucleus of the hypothalamus (ARH) is a brain region
that expresses OFQ/N and ORL-1 important for both sexual behavior and
modulating estradiol feedback loops. Within the ARH, the activation of the
OFQ/N-ORL-1 system facilitates sexual receptivity (lordosis) through the
inhibition of β-endorphin neuronal activity. Estradiol initially activates ARH
β-endorphin neurons to inhibit lordosis. Simultaneously, estradiol upregulates
coexpression of OFQ/N and progesterone receptors and ORL-1 in ARH
β-endorphin neurons. Ovarian hormones regulate pre- and postsynaptic
coupling of ORL-1 to its G protein-coupled signaling pathways. When the
steroid-primed rat is nonreceptive, estradiol acts pre- and postsynaptically
to decrease the ability of the OFQ/N-ORL-1 system to inhibit ARH β-endorphin
neurotransmission. Conversely, when sexually receptive, ORL-1 signaling is
restored to inhibit β-endorphin neurotransmission. Although steroid signaling
that facilitates lordosis converges to deactivate ARH.
Estradiol Activates the Prostate Androgen Receptor and Prostate specific Antigen
Secretion through the Intermediacy of Sex Hormone-binding Globulin

Atif M. Nakhla, Nicholas A. Romas, and William Rosner
J Biol Chem Mar 14, 1997; 272(11): 6838–6841 http://www-jbc.stanford.edu/jbc/

These experiments were designed to examine the relationship between the
effects of steroid hormones mediated by classic intracellular steroid hormone
receptors and those mediated by a signaling system subserved at the plasma
membrane by a receptor for sex hormone binding globulin. It is known that
unliganded sex hormone-binding globulin (SHBG) binds to a receptor (RSHBG)
on prostate membranes. The RSHBG*SHBG complex is rapidly activated by
estradiol to stimulate adenylate cyclase, with a resultant increase in intracellular
cAMP. In this paper we examine the effect of this system on a prostate gene
product known to be activated by androgens, prostate-specific antigen.
We have shown previously that estradiol (E2) participates in a signaling
system that originates, not within the cell, but at the plasma membrane.
Through the intermediacy of the plasma protein, sex hormone-binding
globulin (SHBG), it causes the generation of cAMP. In brief, unliganded
SHBG binds to a receptor (RSHBG) on certain cell surfaces and the
RSHBG*SHBG complex is rapidly activated by E2 to stimulate adenylate cyclase,
with a resultant increase in intracellular cAMP. There is a paucity of information
on events subsequent to the generation of cAMP by this system. In this paper
we examine the effect of E2-SHBG-RSHBG on an androgen responsive gene.
The gene for prostate-specific antigen (PSA) contains an androgen response
element. After binding its cognate ligand, the androgen receptor (AR) interacts
with this response element to initiate PSA mRNA transcription and secretion.
We show that, in the absence of androgens, E2 in concert with SHBG*RSHBG,
acts at the cell membrane to cause secretion of PSA and that this effect is
blocked by anti-androgens. This observation provides a first functional link
between a classic steroid hormone receptor and a cell membrane-mediated
steroidal effect. In serum-free organ culture of human prostates,
dihydrotestosterone caused an increase in prostate specific antigen secretion.
This event was blocked by the anti-androgens cyproterone acetate and
hydroxyflutamide. In the absence of androgens, estradiol added to prostate
tissue, whose RSHBG was occupied by SHBG, reproduced the results seen
with dihydrotestosterone. Neither estradiol alone nor SHBG alone duplicated
these effects. The estradiol*SHBG-induced increase in prostate-specific
antigen was not blocked by anti-estrogens, but was blocked both by anti-
androgens and a steroid (2-methoxyestradiol) that prevents the binding of
estradiol to SHBG. Furthermore, an inhibitor of protein kinase A prevented
the estradiol*SHBG-induced increase in prostate-specific antigen but not
that which followed dihydrotestosterone. These data indicate that there is a
signaling system that amalgamates steroid-initiated intracellular events
with steroid-dependent occurrences generated at the cell membrane and
that the latter signaling system proceeds by a pathway that involves protein
kinase A.
Mechanisms of crosstalk between endocrine systems: Regulation of sex steroid
hormone synthesis and action by thyroid hormones

Paula Duarte-Guterman, Laia Navarro-Martín, Vance L. Trudeau
General and Comparative Endocrinology 203 (2014) 69–85
http://dx.doi.org/10.1016/j.ygcen.2014.03.015

Thyroid hormones (THs) are well-known regulators of development and
metabolism in vertebrates. There is increasing evidence that THs are also
involved in gonadal differentiation and reproductive function. Changes in TH
status affect sex ratios in developing fish and frogs and reproduction
(e.g., fertility), hormone levels, and gonad morphology in adults of species of
different vertebrates. In this review, we have summarized and compared the
evidence for cross-talk between the steroid hormone and thyroid axes and
present a comparative model. We gave special attention to TH regulation of
sex steroid synthesis and action in both the brain and gonad, since these are
important for gonad development and brain sexual differentiation and have
been studied in many species. We also reviewed research showing that
there is a TH system, including receptors and enzymes, in the brains and
gonads in developing and adult vertebrates. Our analysis shows that THs
influences sex steroid hormone synthesis in vertebrates, ranging from fish
to pigs. This concept of crosstalk and conserved hormone interaction has
implications for our understanding of the role of THs in reproduction, and
how these processes may be dysregulated by environmental endocrine
disruptors.
Inverse relationship between hSHBG affinity for testosterone and hSHBG
concentration revealed by surface plasmon resonance

Laurence Heinrich-Balard, Wael Zeinyeh, Henri Déchaud, Pascaline Rivory, et al.
Molecular and Cellular Endocrinology 399 (2015) 201–207
http://dx.doi.org/10.1016/j.mce.2014.10.002

A wide range of human sex hormone-binding globulin (hSHBG) affinity constants
for testosterone (KA_hSHBG) has been reported in literature. To bring new insight
on the KA_hSHBG value, we implemented a study of the molecular interactions
occurring between testosterone and its plasma transport proteins by using
surface plasmon resonance. The immobilization on the sensor-chip of a
testosterone derivative was performed by an oligoethylene glycol linker.
For different plasmas with hSHBG concentrations, an assessment of the
KA_hSHBG was obtained from a set of sensor-grams and curve-fitting these
data.We observed that KA_hSHBG decreased, from at least two decades,
when the plasma hSHBG concentration increased from 4.4 to 680 nmol/L.
Our study shows a wide biological variability of KA_hSHBG that is related
to the hSHBG concentration.
These unexpected results may have a physiological significance and question
the validity of current methods that are recommended for calculating free
testosterone concentrations to evaluate androgen disorders in humans.
Intracrinology in action: Importance of extragonadal sex steroid biosynthesis
and inactivation in peripheral tissues in both women and men.

Editorial
Journal of Steroid Biochemistry & Molecular Biology 145 (2015) 131–132
http://dx.doi.org/10.1016/j.jsbmb.2014.09.012

It seems appropriate, as introduction, to summarize the mechanisms at the
basis of the new paradigm of steroid biosynthesis in the human peripheral
tissues, namely intracrinology. While the first clinical proof of the role of
extragonadal sex steroid biosynthesis was obtained with combined androgen
blockade in men treated for prostate cancer, the first demonstration of the
efficacy of DHEA replacement therapy was on the symptoms of vulvovaginal
atrophy in postmenopausal women; (Archer, this issue).
DHEA is transformed specifically in each cell of each peripheral tissue into
the proper amounts of estrogens and/or androgens, depending upon the
local expression of the appropriate steroid forming enzymes; (Labrie, this issue).
Most importantly, the sex steroids synthesized and acting intracellularly in
peripheral tissues are also inactivated locally before being released in the
extracellular space, thus maintaining the serum levels of estradiol and
testosterone at biologically inactive concentrations, thus avoiding systemic
exposure to sex steroids during menopause as well illustrated by atrophy
of the endometrium.
As mentioned above, that extragonadal androgen biosynthesis is clinically
important became obvious in 1982 when the addition of the antiandrogen
flutamide to castration provided very exciting and unexpected beneficial results
(Labrie, this issue). In fact, combining a pure anti-androgen to castration has
been the first treatment shown to prolong life in prostate cancer and very clearly
confirmed by the prolongation of life of 2.2–4.8 months observed following
addition of MDV-3100 or abiraterone to castration resistant prostate cancer
patients (Grist et al., this issue). (Mizokami et al., this issue) very competently
complement the mechanisms potentially involved in extragonadal steroid
biosynthesis. A repeated observation is the association between serum DHEA
levels and increased longevity, a subject reviewed by Ohlsson et al., this issue.
Most importantly, a subject which remains to be supported by long-term clinical
trials but which shows very promising preclinical data is the possibility of a
beneficial effect of DHEA on brain functions, especially cognition, memory
and delayed development of mild cognitive impairment and Alzheimer’s
disease (see Starka et al.; Soma et al; Pluchino et al; Maggio et al.; Hill et al.,
this issue). The information summarized in the very up-to-date manuscripts
of this special JSBMB issue has the potential of opening the way to a prodrug
replacement therapy already well illustrated on the symptoms and signs of
vulvovaginal atrophy and sexual dysfunction (Archer, this issue). The
administration to sex steroid deficient women of an appropriate amount of
DHEA able to correct the symptoms of vulvovaginal atrophy (mostly estrogen-
sensitive) and sexual dysfunction (androgen-sensitive), and potentially, in the
future, other problems of menopause, does permit to the sex steroid-deficient
women to benefit from a normal/sufficient level of sex steroids in specific tissues
using the enzymes developed over 500 million years to permit a better quality
of life during the menopausal years.

Inactivation of androgens by UDP-glucuronosyltransferase enzymes in humans

Alain Belanger, Georges Pelletier, Fernand Labrie, Olivier Barbier and Sarah Chouinard
TRENDS in Endocrinology and Metabolism 2003; 14(10):473-78
http://dx.doi.org:/10.1016/j.tem.2003.10.005

In humans, 3b-hydroxysteroid dehydrogenase (3β-HSD), 17β-HSD and
5α-reductase activities in androgen target tissues, such as the prostate and
skin, convert dehydroepiandrosterone, androstenedione and testosterone into
the most potent natural androgen dihydrotestosterone (DHT). This androgen
is converted mainly in situ into two phase I metabolites, androsterone (ADT)
and androstane-3α,17β-diol (3α-DIOL), which might be back converted to DHT.
Here, we discuss the recent findings regarding the characterization of specific
UDP glucuronosyltransferases (UGTs), UGT2B7, B15 and B17, responsible for
the glucuronidation of these metabolites. The tissue distribution and cellular
localization of the UGT2B transcripts and proteins in humans clearly indicate
that these enzymes are synthesized in androgen-sensitive tissues. It is
postulated that the conjugating activity of UGT enzymes is the main mechanism
for modulating the action of steroids and protecting the androgen-sensitive
tissues from deleteriously high concentrations of DHT, ADT and 3α-DIOL.
Synthesis and Evaluation of Potential Radioligands for the Progesterone Receptor

R.M. Hoyte, W. Rosner, I.S. Johnson, J. Zielinski, and R. B. Hochberg
J. Med. Chem. 1985; 28: 1695-1699

Several steroidal analogues were synthesized as potential y-emitting radioligands
for the progesterone receptor. Each of these compounds was tested as an inhibitor
of the specific binding of [3H]-17α,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione
(R5020) to the progesterone receptor in rabbit uterine cytosol. R5020 is a well-
known progestin with high affinity for the receptor. Of the compounds synthesized,
aromatic N-substituted (2-17 steroidal carboxamides inhibited the binding only
poorly. Three compounds, 16α-iodo-4-estren-17β-ol-3-one, 17α-[2(E)-iodovinyl]
-4-estren-17β-ol-3-one, and 17α-[2(Z)-iodovinyl]-4-estren-l7β-ol-3-one are
excellent competitors, each having a Ki less than or equal to that of the natural
progestin, progesterone. Since similar iodinated analogues of estrogens
have been shown to be extremely stable both in vivo and in vitro, these compounds
are potentially useful ligands for the progesterone receptor.

Estradiol concentration and the expression of estrogen receptors in the testes of
the domestic goose (Anser anser f. domestica) during the annual reproductive cycle

Leska, J. Kiezun, B. Kaminska, L. Dusza
Domestic Animal Endocrinology 51 (2015) 96–104
http://dx.doi.org/10.1016/j.domaniend.2014.12.002

Seasonal fluctuations in the activity of bird testes are regulated by a complex mechanism
where androgens play a key role. Until recently, the role played by estrogens in males has
been significantly underestimated. However, there is growing evidence that the proper
functioning of the testes is associated with optimal estradiol (E2) concentration
in both the plasma and testes of many mammalian species. Estrogens are
gradually emerging as very important players in hormonal regulation of
reproductive processes in male mammals. Despite the previously mentioned,
it should be noted that estrogenic action is limited by the availability of
specific receptors – estrogen receptor alpha (ERα) and estrogen receptor beta
(ERβ). Interestingly, there is a general scarcity of information concerning the
estrogen responsive system in the testes of male birds, which is of particular
interest in exploring the phenomenon of seasonality of reproduction. To address
this question, we have investigated for the first time the simultaneous
expression of testicular ERα and ERβ genes and proteins with the
accompanying plasma and testicular E2 concentrations during the annual
reproductive cycle of male bird. The research model was the domestic
goose (Anser anser f. domestica), a species whose annual reproductive
cycle can be divided into 3 distinct phases characterized by changes
in testicular activity. It has been revealed that the stable plasma E2 profile
did not correspond to changing intratesticular E2 profile throughout the
experiment. The expression of ERα and ERβ genes and proteins was detected
in gander testes and it fluctuated on a seasonal basis with lower level in
breeding and sexual reactivation stages and higher level during the
nonbreeding stage. Our results demonstrated changes in testicular sensitivity
to estrogens in male domestic goose during the annual reproductive cycle.
The seasonal pattern of estrogen receptors (ERs) expression was analyzed
against the hormonal background and a potential mechanism of ERs regulation
in bird testes was proposed. The present study revealed seasonal variations
in the estrogen responsive system, but further research is needed to fully
explore the role of estrogens in the reproductive tract of male birds.

Effects of 5α-dihydrotestosterone on expression of genes related to steroidogenesis
and spermatogenesis during the sex determination and differentiation periods of
the pejerrey, Odontesthes bonariensis

Anelisa González, Juan I. Fernandino, Gustavo M. Somoza
Comparative Biochemistry and Physiology, Part A 182 (2015) 1–7
http://dx.doi.org/10.1016/j.cbpa.2014.12.003

Sex steroid hormones are important players in the control of sex differentiation
by regulating gonadal development in teleosts. Although estrogens are clearly
associated with the ovarian differentiation in teleosts, the effects of androgens
on early gonadal development are still a matter of debate. Traditionally,
11-ketotestosterone (11-KT) is considered themajor androgen in fish; however,
5α-dihydrotestosterone (5α-DHT), the most potent androgen in tetrapods, was
recently found in fish testis and plasma, but its physiological role is still unknown.
In this context, the expression of genes associated with steroidogenesis and
spermatogenesis, body growth and sex differentiation were assessed in
Odontesthes bonariensis larvae fed with food supplemented with two doses of
5α-DHT (0.1 and 10 μg/g of food) from hatching to 6 weeks of age. At the lowest
dose, 5α-DHT treated larvae showed an estrogenic gene expression pattern, with
low hsd11β2 and high cyp19α1α and er2 expression levels with no differences
in sex ratio. At the highest dose, 5α-DHT produced a male-shifted sex ratio and
the larvae exhibited a gene expression profile characteristic of an advancement
of spermatogenesis, with inhibition of amh and stimulation of ndrg3. No
differences were observed in somatic growth. These results suggest that in
this species, 5α-DHT could have a role on sex differentiation and its effects
can differ according to the dose.
Do androgens link morphology and behavior to produce phenotype-specific
behavioral strategies?

Douglas G. Barron, Michael S. Webster, Hubert Schwabl
Animal Behaviour 100 (2015) 116e124
http://dx.doi.org/10.1016/j.anbehav.2014.11.016

Morphological and behavioral traits often covary with each other, and the links
between them may arise from shared physiological mechanisms. In particular,
androgens such as testosterone have emerged as prime candidates for linking
behaviour and morphology due to the environmental sensitivity and pleiotropic
effects of these hormones. In this study we investigated the hypothesis that
androgens simultaneously relate to morphological and behavioral variation,
thereby producing the integrated reproductive phenotypes of male red-backed
fairy-wrens, Malurus melanocephalus. Males of this species can adopt one of
three discrete breeding phenotypes: breeding in red/black plumage, breeding
in brown plumage, or remaining as nonbreeding brown natal auxiliaries. Although
the expression of morphological traits in this species is regulated by androgens
and phenotypes differ in baseline androgen levels (red/black breeder > brown
breeder > auxiliary), injection with GnRH failed to expose phenotype specific
constraints on androgen production. Observations of territoriality, nestling
feeding and extraterritorial forays revealed phenotype-specific patterns of mating
and parental effort, yet these were largely related to age and were not correlated
with baseline or GnRH-induced androgen levels, or the androgen change between
these points. While these findings support the idea that morphological and
behavioral traits are linked via phenotypic correlations, they do not support
the hypothesis that behavioral differences arise from variation in circulating
androgens or the capacity to produce them.
Effects of sex steroids on expression of genes regulating growth-related
mechanisms in rainbow trout (Oncorhynchus mykiss)

Beth M. Cleveland, Gregory M. Weber
General and Comparative Endocrinology xxx (2015) xxx–xxx
http://dx.doi.org/10.1016/j.ygcen.2014.11.018

Effects of a single injection of 17b-estradiol (E2), testosterone (T), or
5b-dihydrotestosterone (DHT) on expression of genes central to the
growth hormone (GH)/insulin-like growth factor (IGF) axis, muscle
regulatory factors, transforming growth factor-beta (TGFβ) superfamily
signaling cascade, and estrogen receptors were determined in rainbow
trout (Oncorhynchus mykiss) liver and white muscle tissue. In liver in
addition to regulating GH sensitivity and IGF production, sex
steroids also affected expression of IGF binding proteins, as E2, T,
and DHT increased expression of igfbp2β and E2 also increased
expression of igfbp2 and igfbp4. Regulation of this system also occurred
in white muscle in which E2 increased expression of igf1, igf2, and
igfbp5β1, suggesting anabolic capacity may be maintained in white
muscle in the presence of E2. In contrast, DHT decreased expression
of igfbp5β1. DHT and T decreased expression of myogenin, while other
muscle regulatory factors were either not affected or responded similarly
for all steroid treatments. Genes within the TGFβ superfamily signaling
cascade responded to steroid treatment in both liver and muscle,
suggesting a regulatory role for sex steroids in the ability to transmit
signals initiated by TGFβ superfamily ligands, with a greater number
of genes responding in liver than in muscle. Estrogen receptors were
also regulated by sex steroids, with era1 expression increasing for all
treatments in muscle, but only E2- and T-treatment in liver. E2 reduced
expression of erb2 in liver. Collectively, these data identify how
physiological mechanisms are regulated by sex steroids in a manner
that promotes the disparate effects of androgens and estrogens on
growth in salmonids.
Distribution and function of 3′,5′-Cyclic-AMP phosphodiesterases in the human ovary

T.S. Petersen, S.G. Kristensen, J.V. Jeppesen, .., K.T. Macklon, C.Y. Andersen
Molecular and Cellular Endocrinology 403 (2015) 10–20
http://dx.doi.org/10.1016/j.mce.2015.01.004

The concentration of the important second messenger cAMP is regulated by
phosphodiesterases (PDEs) and hence an attractive drug target. However,
limited human data are available about the PDEs in the ovary. The aim of the
present study was to describe and characterise the PDEs in the human ovary.
Results were obtained by analysis of mRNA microarray data from follicles and
granulosa cells (GCs), combined RT-PCR and enzymatic activity analysis in GCs,
immunohisto-chemical analysis of ovarian sections and by studying the effect
of PDE inhibitors on progesterone production from cultured GCs. We found that
PDE3, PDE4, PDE7 and PDE8 are the major families present while PDE11A
was not detected. PDE8B was differentially expressed during folliculogenesis.
In cultured GCs, inhibition of PDE7 and PDE8 increased basal progesterone
secretion while PDE4 inhibition increased forskolin-stimulated progesterone
secretion. In conclusion, we identified PDE3, PDE4, PDE7 and PDE8 as
the major PDEs in the human ovary.
Diethylstilbestrol can effectively accelerate estradiol-17-O-glucuronidation, while
potently inhibiting estradiol-3-O-glucuronidation

Liangliang Zhu, Ling Xiao, Yangliu Xia, .., Yan Wu, Ganlin Wu, Ling Yang
Toxicology and Applied Pharmacology 283 (2015) 109–116
http://dx.doi.org/10.1016/j.taap.2015.01.003

This in vitro study investigates the effects of diethylstilbestrol (DES), a widely
used toxic synthetic estrogen, on estradiol-3- and 17-O- (E2-3/17-O)
glucuronidation, via culturing human liver microsomes (HLMs) or
recombinant UDP-glucuronosyl-transferases (UGTs) with DES and E2.
DES can potently inhibit E2-3-O-glucuronid-ation in HLM, a probe reaction
for UGT1A1. Kinetic assays indicate that the inhibition follows a competitive
inhibition mechanism, with the Ki value of 2.1 ± 0.3 μM, which is less than
the possible in vivo level. In contrast to the inhibition on E2-3-O-glucuronidation,
the acceleration is observed on E2-17-O-glucuronidation in HLM, in which
cholestatic E2-17-O-glucuronide is generated. In the presence of DES
(0–6.25 μM), Km values for E2-17-Oglucuronidation are located in the
range of 7.2–7.4 μM, while Vmax values range from 0.38 to 1.54 nmol/min/mg.
The mechanism behind the activation in HLM is further demonstrated by
the fact that DES can efficiently elevate the activity of UGT1A4 in catalyzing
E2-17-O-glucuronidation. The presence of DES (2 μM) can elevate Vmax from
0.016 to 0.81 nmol/min/mg, while lifting Km in a much lesser extent from 4.4 to
11 μM. Activation of E2-17-O-glucuronidation is well described by a two binding
site model, with KA, α, and β values of 0.077 ± 0.18 μM, 3.3 ± 1.1 and 104 ± 56,
respectively. However, diverse effects of DES towards E2-3/17-O-glucuronidation
are not observed in liver microsomes from several common experimental animals.
In summary, this study issues new potential toxic mechanisms for DES: potently
inhibiting the activity of UGT1A1 and powerfully accelerating the formation of
cholestatic E2-17-O-glucuronide by UGT1A4.
Dehydroepiandrosterone: A neuroactive steroid

Luboslav Stárka, Michaela Dusková, Martin Hill
Journal of Steroid Biochemistry & Molecular Biology 145 (2015) 254–260
http://dx.doi.org/10.1016/j.jsbmb.2014.03.008

Dehydroepiandrosterone (DHEA) and its sulfate bound form (DHEAS) are important
steroids of mainly adrenal origin. They are produced also in gonads and in the brain.
Dehydroepiandrosterone easily crosses the brain–blood barrier and in part is also
produced locally in the brain tissue. In the brain, DHEA exerts its effects after
conversion to either testosterone and dihydrotestosterone or estradiol via androgen
and estrogen receptors present in the most parts of the human brain, through
mainly non-genomic mechanisms, or eventually indirectly via the effects of its
metabolites formed locally in the brain. As a neuroactive hormone, DHEA in
cooperation with other hormones and transmitters significantly affects some
aspects of human mood, and modifies some features of human emotions and
behavior. It has been reported that its administration can increase feelings of well-
being and is useful in ameliorating atypical depressive disorders. It has
neuroprotective and antiglucocorticoid activity and modifies immune reactions,
and some authors have also reported its role in degenerative brain diseases.
Here we present a short overview of the possible actions of dehydroepiandrosterone
and its sulfate in the brain, calling attention to various mechanisms of their action
as neurosteroids and to prospects for the knowledge of their role in brain disorders.
Androgens and mammalian male reproductive tract development

Aki Murashima, Satoshi Kishigami, Axel Thomson, Gen Yamada
Biochimica et Biophysica Acta 1849 (2015) 163–170
http://dx.doi.org/10.1016/j.bbagrm.2014.05.020

One of the main functions of androgen is in the sexually dimorphic development of
the male reproductive tissues. During embryogenesis, androgen determines the
morphogenesis of male specific organs, such as the epididymis, seminal vesicle,
prostate and penis. Despite the critical function of androgens in masculinization,
the downstream molecular mechanisms of androgen signaling are poorly
understood. Tissue recombination experiments and tissue specific androgen
receptor (AR) knockout mouse studies have revealed epithelial or mesenchymal
specific androgen-AR signaling functions. These findings also indicate that
epithelial–mesenchymal interactions are a key feature of AR specific activity,
and paracrine growth factor action may mediate some of the effects of androgens.
This review focuses on mouse models showing the interactions of androgen and
growth factor pathways that promote the sexual differentiation of reproductive organs.
Recent studies investigating context dependent AR target genes are also discussed.
This article is part of a Special Issue entitled: Nuclear receptors in animal development.

All sex steroids are made intracellularly in peripheral tissues by the mechanisms of
intracrinology after menopause

Fernand Labrie
Journal of Steroid Biochemistry & Molecular Biology 145 (2015) 133–138
http://dx.doi.org/10.1016/j.jsbmb.2014.06.001

Following the arrest of estradiol secretion by the ovaries at menopause, all estrogens
and all androgens in postmenopausal women are made locally in peripheral target
tissues according to the physiological mechanisms of intracrinology. The locally
made sex steroids exert their action and are inactivated intracellularly without
biologically significant release of the active sex steroids in the circulation.The
level of expression of the steroid-forming and steroid-inactivating enzymes is
specific to each cell type in each tissue, thus permitting to each cell/tissue to
synthesize a small amount of androgens and/or estrogens in order to meet the
local physiological needs without affecting the other tissues of the organism.
Achieved after 500 million years of evolution, combination of the arrest of ovarian
estrogen secretion, the availability of high circulating levels of DHEA and the
expression of the peripheral sex steroid-forming enzymes have permitted the
appearance of menopause with a continuing access to intra-tissular sex steroids
for the individual cells/tissues without systemic exposure to circulating estradiol.
In fact, one essential condition of menopause is to maintain serum estradiol at
biologically inactive (subthreshold) concentrations, thus avoiding stimulation of the
endometrium and risk of endometrial cancer. Measurement of the low levels of
serum estrogens and androgens in postmenopausal women absolutely requires
the use of MS/MS-based technology in order to obtain reliable accurate, specific
and precise assays. While the activity of the series of steroidogenic enzymes can
vary, the serum levels of DHEA show large individual variations going from barely
detectable to practically normal “premenopausal” values, thus explaining the
absence of menopausal symptoms in about 25% of women. It should be added
that the intracrine system has no feedback elements to adjust the serum levels
of DHEA, thus meaning that women with low DHEA activity will not be improved
without external supplementation. Exogenous DHEA, however, follows the same
intracrine rules as described for endogenous DHEA, thus maintaining serum
estrogen levels at subthreshold or biologically inactive concentrations. Such blood
concentrations are not different from those observed in normal postmenopausal
women having high serum DHEA concentrations. Androgens, on the other hand,
are practically all made intracellularly from DHEA by the mechanisms of intracrinology
and are always maintained at very low levels in the blood in both pre- and
postmenopausal women. Proof of the importance of intracrinology is also provided,
among others, by the well-recognized benefits of aromatase inhibitors and
anti-estrogens used successfully for the treatment of breast cancer in
postmenopausal women where all estrogens are made locally. Each medical
indication for the use of DHEA, however, requires clinical trials performed
according to the FDA guidelines and the best rules of clinical medicine.
A multi-step, dynamic allosteric model of testosterone’s binding to sex hormone
binding globulin

Mikhail N. Zakharov, Shalender Bhasin, Thomas G. Travison, Ran Xue, et al.
Molecular and Cellular Endocrinology 399 (2015) 190–200
http://dx.doi.org/10.1016/j.mce.2014.09.001

Purpose: Circulating free testosterone (FT) levels have been used widely in the
diagnosis and treatment of hypogonadism in men. Due to experimental
complexities in FT measurements, the Endocrine Society has recommended
the use of calculated FT (cFT) as an appropriate approach for estimating FT.
We show here that the prevailing model of testosterone’s binding to SHBG,
which assumes that each SHBG dimer binds two testosterone molecules
and that the two binding sites on SHBG have similar binding affinity is
erroneous and provides FT values that differ substantially from those
obtained using equilibrium dialysis.
Methods: We characterized testosterone’s binding to SHBG using
binding isotherms, ligand depletion curves, and isothermal titration
calorimetry (ITC). We derived a new model of testosterone’s binding to
SHBG from these experimental data and used this model to determine
FT concentrations and compare these values with those derived from
equilibrium dialysis.
Results: Experimental data on testosterone’s association with SHBG
generated using binding isotherms including equilibrium binding, ligand
depletion experiments, and ITC provide evidence of a multi-step dynamic
process, encompassing at least two inter-converting microstates in unliganded
SHBG, readjustment of equilibria between unliganded states upon binding
of the first ligand molecule, and allosteric interaction between two binding
sites of SHBG dimer. FT concentrations in men determined using the new
multistep dynamic model with complex allostery did not differ from those
measured using equilibrium dialysis. Systematic error in calculated FT
vales in females using Vermeulen’s model was also significantly reduced.
In European Male Aging Study, the men deemed to have low FT (<2.5th
percentile) by the new model were at increased risk of sexual symptoms
and elevated LH.
Conclusion: Testosterone’s binding to SHBG is a multi-step dynamic
process that involves complex allostery within SHBG dimer. FT values
obtained using the new model have close correspondence with those
measured using equilibrium dialysis.

Cohesin modulates transcription of estrogen-responsive genes

Jisha Antony, Tanushree Dasgupta, Jenny M. Rhodes, Miranda V. McEwan, et al.
Biochimica et Biophysica Acta 1849 (2015) 257–269
http://dx.doi.org/10.1016/j.bbagrm.2014.12.011

The cohesin complex has essential roles in cell division, DNA damage repair
and gene transcription. The transcriptional function of cohesin is thought to
derive from its ability to connect distant regulatory elements with gene promoters.
Genome-wide binding of cohesin in breast cancer cells frequently coincides
with estrogen receptor alpha (ERα), leading to the hypothesis that cohesin
facilitates estrogen-dependent gene transcription. We found that cohesin
modulates the expression of only a subset of genes in the ER transcription
program, either activating or repressing transcription depending on the gene
target. Estrogen-responsive genes most significantly influenced by cohesin
were enriched in pathways associated with breast cancer progression such
as PI3K and ErbB1. In MCF7 breast cancer cells, cohesin depletion enhanced
transcription of TFF1 and TFF2, and was associated with increased ER binding
and increased interaction between TFF1 and its distal enhancer situated
within TMPRSS3. In contrast, cohesin depletion reduced c-MYC mRNA and
was accompanied by reduced interaction between a distal enhancer of c-MYC
and its promoters. Our data indicates that cohesin is not a universal facilitator
of ER-induced transcription and can even restrict enhancer–promoter communication.
We propose that cohesion modulates transcription of estrogen-dependent genes
to achieve appropriate directionality and amplitude of expression.
Angiogenesis in Breast Cancer and its Correlation with Estrogen, Progesterone
Receptors and other Prognostic Factors

Jyotsna Naresh Bharti, Poonam Rani, Vinay Kamal, Prem Narayan Agarwal
Journal of Clinical and Diagnostic Research. 2015 Jan, Vol-9(1): EC05-EC07
http://dx.doi.org:/10.7860/JCDR/2015/10591.5447

Purpose: The  aim  of  study  is  to  evaluate  angiogenesis using  CD34,  in
estrogen,  progesterone  positive  and  negative breast cancer  and  to  correlate
the  microvessel  density  with known  histological  prognostic  factors,
morphological  type  of breast carcinoma and lymph node metastasis.
Materials and Methods: Twenty eight untreated cases of breast cancer were
included  in  the  study  and  paraffin  embedded  sections  were  obtained
from  representative  mastectomy specimen of breast cancer patient. The sections
were stained with hematoxylin and eosin stain and immunohistochemistry was
performed using CD34, estrogen, progesterone, cytokeratin and epithelial
membrane antigen  antibody.  Angiogenesis was analyzed using CD 34 antibody.
For statistical analysis, cases were grouped into estrogen, progesterone positive
and negative receptors.
Results: Mean microvessel density in ER-/PR-, ER-/ PR+, ER+/PR-, ER+/PR+
was 15.45, 14.83, 11, 10.89 respectively.  A significant correlation was found
between ER receptors and mean vascular density with p-value (< 0.05).
A significant difference was observed in mean vascular density between
the four groups comprising (p-value < 0.05).  Infiltrating duct carcinoma
(NOS) grade III has got the highest mean microvessel density (14.17)
followed by grade II (12.93) and grade I (12.33).
Conclusion: Information about prognostic factors in breast cancer
patients may lead to better ways to identify those patients at high risk
who might benefit from adjuvant therapies.

Combined blockade of testicular and locally made androgens in prostate cancer:
A highly significant medical progress based upon intracrinology

Fernand Labrie
Journal of Steroid Biochemistry & Molecular Biology 145 (2015) 144–156
http://dx.doi.org/10.1016/j.jsbmb.2014.05.012

Recently two drugs, namely the antiandrogen MDV-3100 and the inhibitor
of 17β-hydroxylase abiraterone have been accepted by the FDA for the
treatment of castration-resistant prostate cancer (CRPC) with or without
previous chemotherapy, with a prolongation of overall survival of 2.2–4.8months.
While medical (GnRH agonist) or surgical castration reduces the serum levels
of testosterone by about 97%, an important concentration of testosterone and
dihydrotestosterone remains in the prostate and activates the androgen receptor
(AR), thus offering an explanation for the positive data obtained in CRPC. In fact,
explanation of the response observed with MDV-3100 or enzalutamide in CRPC
is essentially a blockade of the action or formation of intraprostatic androgens.
In addition to the inhibition of the action or formation of androgens made locally
by the mechanisms of intracrinology, increased AR levels and AR mutations can
be involved, especially in very advanced disease.

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Pituitary Neuroendocrine Axis

Writer and Curator: Larry H. Bernstein, MD, FCAP 

Hypothalamic-Pituitary-Endocrine Axis

The attachments below are fully illustrated annotated outline of the discussion we are about to be engaged in.

http://bcs.whfreeman.com/thelifewire/content/chp42/4202002.html

Animation 8.5: The Hypothalamus and Endocrine Function

The hypothalamus is a small, yet vitally important, brain region that integrates the body’s two communication systems: the endocrine and nervous systems. It links the two by sending and receiving signals from other regions of the nervous system while also controlling the body’s “master gland“—the pituitary gland. The pituitary, in turn, controls most other endocrine organs of the body.

The interaction between the hypothalamus, pituitary, and other endocrine glands is known as the hypothalamic–pituitary–endocrine axis. In one animation, we examine the hypothalamic control of the pituitary gland, and we show the endocrine glands that the pituitary controls. In another, we examine a phenomenon called a negative feedback loop, in which hormones from endocrine glands influence the action of the hypothalamus.

http://www.mindsmachine.com/av08.05.script.html

Hypothalamus-Pituitary Overview

The hormonal control center of the body can be found at the base of the brain, in a tiny pea-sized structure, called the pituitary gland, and an overlying region, called the hypothalamus. Because the pituitary controls many other endocrine glands, it is known as the “master gland” of the body. However, the hypothalamus wields even greater power, because it controls the pituitary gland.

The pituitary gland consists of two distinct parts. One part, the anterior pituitary, originates from glandular tissue. The other part, the posterior pituitary, consists of neural tissue and is essentially an extension of the brain.

As an extension of the brain, the posterior pituitary contains axons from neurons in the hypothalamus. The cell bodies of these neurons are clustered in groups, called nuclei. A number of nuclei exist in the hypothalamus; the important ones for the posterior pituitary are the paraventricular and supraoptic nuclei.

The neurons that extend into the posterior pituitary produce either the hormone arginine vasopressin (abbreviated AVP) or the hormone oxytocin. These hormones are made in the cell bodies and then transported to the axon terminals.

The axon terminals abut tiny capillaries in the posterior pituitary. If a neuron is stimulated and fires an action potential, the neuron releases its hormones from the axon terminals. The hormones quickly enter the capillaries and flow with the blood into the general circulation of the body.

The AVP-producing (arginine-vasopressin, related to angiotensin and vasopressin peptides) neurons respond to signals relating to thirst and water regulation. If body fluids have a high osmolality, this signal causes the neurons to release AVP into the bloodstream. AVP stimulates the kidneys to conserve water. Although water conservation is its major role, AVP also triggers blood vessels to contract, which increases blood pressure.

The oxytocin-producing neurons respond to stimulation from a suckling baby. When these neurons fire action potentials, they release oxytocin into the general circulation. Oxytocin reaches the mammary glands, triggering them to express milk. These neurons are also activated during childbirth, during which oxytocin triggers uterine contractions. But we have also seen in a previous document that the action of oxytocin is also tied to social behavior, which is expressed as empathy, or anxiety, or anger control in aggressive behavior.  There is another layer in this story that is related to glutaminergic chemistry and GABAergic response.

Unlike the posterior pituitary, the anterior pituitary consists of glandular tissue. The gland consists of numerous cell types, which specialize in making and releasing specific hormones. However, these hormones are only released (or, in some cases, inhibited from being released) in response to hypothalamic hormones.

An elaborate web of capillaries, called the hypothalamic-pituitary portal system, connects the glandular cells with neurons from the hypothalamus. The hypothalamic neurons abut the capillaries, and when stimulated, release hormones into the portal circulation.

The hypothalamic hormones are peptides that travel directly to the cells of the anterior pituitary. Here, a specific hormone affects a specific type of anterior pituitary cell. Each cell type, in turn, produces and releases its own hormones into the general circulation. Once released, the anterior pituitary hormones travel throughout the body to their various targets.

The hypothalamic hormones are generally called releasing hormones, because most of them trigger the anterior pituitary to release hormones. Some, however, inhibit hormone release, as indicated by their specific names. The anterior pituitary hormones are called tropic hormones. Click on these hormone pairs to learn the function of the tropic hormones in the body.

Negative Feedback Loops

The hypothalamus initiates a chain of events that control the endocrine system. It releases hormones that trigger the anterior pituitary to release more hormones. These hormones – control vital endocrine organs: the adrenal glands, thyroid, ovaries, testes, which in turn influence the pituitary gland by a feedback loop.. Although the hypothalamus drives the system, the hypothalamus is kept in check by this negative feedback loop.

Let’s look at a negative feedback loop using the hormones of the adrenal cortex as an example. In response to stress signals, the hypothalamus releases corticotropin-releasing hormone, or CRH. CRH triggers the anterior pituitary to release adrenocorticotropic hormone, or ACTH, which triggers the adrenal cortex to release a steroid hormone called cortisol. The same mechanism pertains to the thyroid and the relationship between thyroid stimulating hormone (TSH) and thyroid hormone.

Cortisol has many effects on different target organs in the body, but the primary one is to increase glucose in the blood. This sugar is an energy resource that allows the body to respond to physiological or psychological stress. Cortisol, estrogen and androgen are not peptide hormones.  They are steroid hormones, synthesized with a cholesterol backbone, and are also related to the bile secreted by the liver.  While peptide hormones have an amino acid sequence and are highly polar, this is not the case for the steroids.

In addition to acting on organs and tissues throughout the body, the hormones travel through the bloodstream back to the brain, where they inhibit the release of CRH.

Without CRH, the anterior pituitary does not release ACTH. In addition to this effect, the cortisol also acts directly on the anterior pituitary to inhibit ACTH release. Without ACTH, the adrenal cortex stops releasing cortisol.

This interaction is an example of a negative feedback loop. In this loop, the output of the system—the hormones from the adrenal cortex—ultimately diminish the input from the system—the hormones from the hypothalamus and anterior pituitary. This system turns on cortisol release, but then turns it off before cortisol levels get too high, keeping them at a fairly steady level.

This description is not complete without mention of the relationship between growth hormone (GSH) and the liver.  Growth hormone stimulates the liver to produce insulin-like peptide 1 (IL-1), which acts on the pancreatic islet cells to produce insulin.  There is also a competing relationship between glucagon, synthesized by the liver, which acts on glycogenolysis, and insulin, which facilitates glucose entry into peripheral tissues, and is therefore, anabolic.   Insofar as GSH is concerned, it is pleiotrophic because it promotes insulin secretion by the pancreas, but it also raises blood glucose levels.

CONCLUSION

Through its release of hormones, the hypothalamus controls reproduction, growth, metabolism, water conservation, blood pressure, lactation, childbirth, and responses to stress. Through its connections with other regions of the nervous system, the hypothalamus controls many other bodily functions.

http://www.mindsmachine.com/av08.05.script.html

HPA_Axis_Diagram_(Brian_M_Sweis_2012)

HPA_Axis_Diagram_(Brian_M_Sweis_2012)

Hypothalamic-Pituitary-Adrenal Axis

http://upload.wikimedia.org/wikipedia/commons/5/55/HPA_Axis_Diagram_%28Brian_M_Sweis_2012%29.png

The interactions among the organs that constitute the HPA axis, a major part of the neuroendocrine system that controls reactions to stress and regulates many body processes, including digestion, the immune system, mood and emotions, sexuality and energy storage and expenditure is illustrated in the picture above. It is the common mechanism for interactions among glands, hormones, and parts of the midbrain that mediate the general adaptation syndrome (GAS).[1] While steroids are produced only by vertebrates, the physiological role of the HPA axis and corticosteroids in stress response is so fundamental that analogous systems can be found in invertebrates and monocellular organisms as well.

Anatomical connections between brain areas such as the amygdala, hippocampus, prefrontal cortex and hypothalamus facilitate activation of the HPA axis. Sensory information arriving at the lateral aspect of the amygdala is processed and conveyed to the central nucleus, which projects to several parts of the brain involved in responses to fear. At the hypothalamus, fear-signaling impulses activate both the sympathetic nervous system and the modulating systems of the HPA axis.

The key elements of the HPA axis are:

The paraventricular nucleus of the hypothalamus, which contains neuroendocrine neurons that synthesize and secrete vasopressin and corticotropin-releasing hormone (CRH). These two peptides regulate:

The anterior lobe of the pituitary gland. In particular, CRH and vasopressin stimulate the secretion of adrenocorticotropic hormone (ACTH), once known as corticotropin. ACTH in turn acts on:

the adrenal cortex, which produces glucocorticoid hormones (mainly cortisol in humans) in response to stimulation by ACTH. Glucocorticoids in turn act back on the hypothalamus and pituitary (to suppress CRH and ACTH production) in a negative feedback cycle.

CRH and vasopressin are released from neurosecretory nerve terminals at the median eminence. CRH is transported to the anterior pituitary through the portal blood vessel system of the hypophyseal stalk and vasopressin is transported by axonal transport to the posterior pituitary. There, CRH and vasopressin act synergistically to stimulate the secretion of stored ACTH from corticotrope cells. ACTH is transported by the blood to the adrenal cortex of the adrenal gland, where it rapidly stimulates biosynthesis of corticosteroids such as cortisol from cholesterol. Cortisol is a major stress hormone and has effects on many tissues in the body, including the brain. In the brain, cortisol acts on two types of receptor – mineralocorticoid receptors and glucocorticoid receptors, and these are expressed by many different types of neurons. One important target of glucocorticoids is the hypothalamus, which is a major controlling centre of the HPA axis.

http://en.wikipedia.org/wiki/Hypothalamic%E2%80%93pituitary%E2%80%93adrenal_axis

Hypothalamic–pituitary–gonadal axis

This axis controls development, reproduction, and aging in animals. Gonadotropin-releasing hormone (GnRH) is secreted from the hypothalamus by GnRH-expressing neurons. The anterior portion of the pituitary gland produces luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and the gonads produce estrogen and testosterone.

In oviparous organisms (e.g. fish, reptiles, amphibians, birds), the HPG axis is commonly referred to as the hypothalamus-pituitary-gonadal-liver axis (HPGL-axis) in females. Many egg-yolk and chorionic proteins are synthesized heterologously in the liver, which are necessary for oocyte growth and development. Examples of such necessary liver proteins are vitellogenin and choriogenin.

The hypothalamus is located in the brain and secretes GnRH. GnRH travels down the anterior portion of the pituitary via the hypophyseal portal system and binds to receptors on the secretory cells of the adenohypophysis. In response to GnRH stimulation these cells produce LH and FSH, which travel into the blood stream.

These two hormones play an important role in communicating to the gonads. In females FSH and LH act primarily to activate the ovaries to produce estrogen and inhibin and to regulate the menstrual cycle and ovarian cycle. Estrogen forms a negative feedback loop by inhibiting the production of GnRH in the hypothalamus. Inhibin acts to inhibit activin, which is a peripherally produced hormone that positively stimulates GnRH-producing cells. Follistatin, which is also produced in all body tissue, inhibits activin and gives the rest of the body more control over the axis. In males LH stimulates the interstitial cells located in the testes to produce testosterone, and FSH plays a role in spermatogenesis. Only small amounts of estrogen are secreted in males. Recent research has shown that a neurosteroid axis exists, which helps the cortex to regulate the hypothalamus’s production of GnRH.

http://en.wikipedia.org/wiki/Hypothalamic%E2%80%93pituitary%E2%80%93gonadal_axis

Hypothalamic–pituitary–thyroid axis

thyroid function axis

thyroid function axis

Short overview of thyroid homeostasis

Short overview of thyroid homeostasis

http://upload.wikimedia.org/wikipedia/commons/thumb/d/d1/Thyroid_system.svg/640px-Thyroid_system.svg.png

Thyroid homeostasis results from a multi-loop feedback system that is found in virtually all higher vertebrates. Proper function of thyrotropic feedback control is indispensable for growth, differentiation, reproduction and intelligence. Very few animals (e.g. axolotls and sloths) have impaired thyroid homeostasis that exhibits a very low set-point that is assumed to underlie the metabolic and ontogenetic anomalies of these animals.

The pituitary gland secretes thyrotropin (TSH; Thyroid Stimulating Hormone) that stimulates the thyroid to secrete thyroxine (T4) and, to a lesser degree, triiodothyronine (T3). The major portion of T3, however, is produced in peripheral organs, e.g. liver, adipose tissue, glia and skeletal muscle by deiodination from circulating T4. Deiodination is controlled by numerous hormones and nerval signals including TSH, vasopressin and catecholamines.

Both peripheral thyroid hormones (iodothyronines) inhibit thyrotropin secretion from the pituitary (negative feedback). Consequently, equilibrium concentrations for all hormones are attained.

TSH secretion is also controlled by thyrotropin releasing hormone (thyroliberin, TRH), whose secretion itself is again suppressed by plasma T4 and T3 in CSF (long feedback, Fekete–Lechan loop). Additional feedback loops are ultrashort feedback control of TSH secretion (Brokken-Wiersinga-Prummel loop) and linear feedback loops controlling plasma protein binding. Convergence of multiple afferent signals in the control of TSH release may be the reason for the observation that the relation between free T4 concentration and TSH levels deviates from a pure loglinear relation that has previously been proposed.

Thyrotropic feedback control - Jwdietrich

Thyrotropic feedback control – Jwdietrich

“Thyrotropic feedback control” by Jwdietrich2 – Own work. Licensed under CC BY 3.0 via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:Thyrotropic_feedback_control.svg#mediaviewer/File:Thyrotropic_feedback_control.svg

The above has been a broad stroke of the Pituitary-Hypophysial-Endocrine Axis. It does not take into account another level of complexity in the receptor mediated reactions.

Anatomy of the pituitary, thyroid, parathyroid and adrenal glands

Ritchie, J.E., Balasubramanian, S.P
Surgery (United Kingdom) 2014; 32 (10), pp. 499-503

A detailed understanding of anatomy is essential for several reasons: to enable
accurate diagnosis and plan appropriate management; to perform surgery in a safe
and effective manner avoiding damage to adjacent structures and; to anticipate and
recognize variations in normal anatomy. This chapter will cover the anatomy of four
major endocrine glands (thyroid, parathyroid, pituitary and adrenal). Other
endocrine glands (such as the hypothalamus, pineal gland, thymus, endocrine
pancreas and the gonads) are beyond the scope of this chapter. In addition to gross
anatomy, clinically relevant embryological and histological details of these four
glands are also discussed.

Physiology of the pituitary, thyroid, parathyroid and adrenal glands

Mihai, R.
Surgery (United Kingdom) 2014; 32 (10), pp. 504-512

The pituitary gland is made of clusters of cells producing specific hormones that
control growth (growth hormone), thyroid function (triiodothyronine (T3) and
thyroxine (T4)), adrenal function (adrenocorticotrophic hormone (ACTH)) and gonadal
function (follicle-timulating hormone and luteinizing hormone). In addition, the neurons
that join the posterior pituitary (neurohypophysis) secrete vasopressin – the
antidiuretic hormone involved in maintaining water balance. The negative feedback
loop is the basic mechanism to control the regulation of all endocrine glands.
Hypothalamic peptides – releasing hormones (e.g. TRH, corticotrophin-releasing
hormone) reach the hypophysis via the portal venous system and induce the
secretion of specific stimulating hormones (e.g. thyroid-stimulating hormone,
ACTH) that drive the end-target endocrine cells to secrete hormones (e.g.
thyroid hormones – T3 and T4 or adrenal hormones – cortisol, dehydro-epiandrosterone sulphate). The plasma levels of these circulating hormones inhibit
the pituitary (short feedback) or the hypothalamus (long feedback) and limit the further
release of releasing and stimulating hormones. The effects of circulating hormones
on different tissues are mediated via specific receptors on the cell membrane (e.g.
vasopressin receptors), in the cytoplasm (steroid receptor for cortisol) or in the
nucleus (e.g. thyroid hormone receptors). Understanding the physiological effects of
peripheral hormones helps understanding the mechanisms by which clinical signs
and symptoms develop in diseases characterized by excessive hormone secretion
(e.g. thyrotoxicosis, Cushing syndrome, phaeochromocytomas) or lack of hormone
secretion (e.g. diabetes insipidus). The parathyroid gland and adrenal medulla are
not controlled by the pituitary but play important roles in calcium metabolism
and the adrenergic (sympathetic nervous system) function respectively.

Pathology of the pituitary, parathyroid, thyroid and adrenal glands

Okpokam, A., Johnson, S.J.
Surgery (United Kingdom) 2014; 32 (10), pp. 513-524

The clinical presentation of pathology of these endocrine organs is usually of hyper-
or hypo-secretion of hormones, enlargement and/or nodules found either clinically
or radiologically. Hyperfunction usually results from hyperplasia or functioning
neoplasms. Hypofunction usually represents destruction of the gland. Neoplasms
may be functional or non-functional, and benign or malignant, the latter may also
present as distant metastases. Many cases benefit from multidisciplinary team
discussion, pre- and/or post-operatively. Most hyperplasia/neoplasia is sporadic,
but a significant minority occurs in familial settings, for example multiple endocrine
neoplasia (MEN) syndromes type 1 and type 2. Any of these endocrine organs
can also be involved by non-endocrine primary malignancy, either by direct
infiltration or blood-borne metastasis.

Neuroanatomy and Physiology of the Avian Hypothalamic/Pituitary Axis: Clinical Aspects

Midge Ritchie
Vet Clin Exot Anim 17 (2014) 13–22
http://dx.doi.org/10.1016/j.cvex.2013.09.005

The pituitary gland (hypophysis) is a small gland that is intimately connected
to the hypothalamus at the base of the brain and is classified as either
adenohypophysis or neurohypophysis.

The avian thyroid glands are paired glands located ventrolaterally to the
trachea. The histology of the avian thyroids is the same as in mammals:
organized into follicles filled with colloid and lined with cuboidal epithelial cells
that secrete into the interior of the follicles.

Adrenal lesions in birds have been described postmortem only. Antemortem
diagnosis of adrenal disease has not been reported in birds. It is believed,
however, that the ACTH stimulation and low dose dexamethasone suppression
test can potentially be used in birds for the diagnosis of hypoadrenocorticism
and hyperadrenocorticism.

In birds, as in other verterbrates, gonadotropin-releasing hormone (GnRH), also
known as luteinizing hormone releasing hormone (LHRH), released from the
hypothalamus, is the primary factor responsible for the release of gonadotropins
(luteinizing hormone [LH], follicle-stimulating hormone [FSH], and prolactin) by the
anterior pituitary gland. Gonadotropins bind to their gonadal receptors and affect
the function of the ovaries and testes.

The 2 hormones of the neurohypophysis, arginine vasotocin (AVT) and mesotocin
(MT), are produced by and secreted from separate neurosecretory neurons. AVT
and MT are transported bound to carrier proteins by axoplasmic transport. The
hormones are then stored in pars nervosa before release.

Endocrine responses to critical illness: Novel insights and therapeutic implications

Boonen, E., Van Den Berghe, G.
Journal of Clinical Endocrinology and Metabolism 2014; 99 (5), pp. 1569-1582

Context: Critical illness, an extreme form of severe physical stress, is characterized
by important endocrine and metabolic changes. Due to critical care medicine,
survival from previously lethal conditions has become possible, but many
patients now enter a chronic phase of critical illness. The role of the endocrine
and metabolic responses to acute and prolonged critical illness in mediating or
hampering recovery remains highly debated. Evidence Acquisition: The recent
literature on changes within the hypothalamic-pituitary-thyroid axis and the
hypothalamic-pituitary-adrenal axis and on hyperglycemia in relation to recovery
from critical illness was critically appraised and interpreted against previous
insights. Possible therapeutic implications of the novel insights were analyzed.
Specific remaining questions were formulated. Evidence Synthesis: In recent years,
important novel insights in the pathophysiology and the consequences of some
of these endocrine responses to acute and chronic critical illness were generated.
Acute endocrine adaptations are directed toward providing energy and substrates
for the vital fight-or-flight response in a context of exogenous substrate deprivation.
Distinct endocrine and metabolic alterations characterize the chronic phase of critical
illness, which seems to be no longer solely beneficial and could hamper recovery and
rehabilitation.Conclusions: Important novel insights reshape the current view on
endocrine and metabolic responses to critical illness and further clarify underlying
pathways. Although many issues remain unresolved, some therapeutic implications
were already identified. More work is required to find better treatments, and the
optimal timing for such treatments, to further prevent protracted critical illness, to
enhance recovery thereof, and to optimize rehabilitation.

Endocrinopathies after allogeneic and autologous transplantation of hematopoietic
stem cells

Orio, F., Muscogiuri, G., Palomba, S., (…), Colao, A., Selleri, C.
Scientific World Journal 2014; 2014, 282147

Early and late endocrine disorders are among the most common complications in
survivors after hematopoietic allogeneic- (allo-) and autologous- (auto-stem cell
transplant (HSCT). This review summarizes main endocrine disorders reported in
literature and observed in our center as consequence of auto- and allo-HSCT and
outlines current options for their management. Gonadal impairment has been found
early in approximately two-thirds of auto- and allo-HSCT patients: 90-99% of
women and 60-90% of men. Dysfunctions of the hypothalamus-pituitary-growth
hormone/insulin growth factor-I axis, hypothalamus-pituitary-thyroid axis, and
hypothalamus-pituitary-adrenal axis were documented as later complications,
occurring in about 10, 30, and 40% of transplanted patients, respectively. Moreover,
overt or subclinical thyroid complications (including persistent low-T3 syndrome,
chronic thyroiditis, subclinical hypo- or hyperthyroidism, and thyroid carcinoma),
gonadal failure, and adrenal insufficiency may persist many years after HSCT. Our
analysis further provides evidence that main recognized risk factors for endocrine
complications after HSCT are the underlying disease, previous pretransplant
therapies, the age at HSCT, gender, total body irradiation, posttransplant
derangement of immune system, and in the allogeneic setting, the presence of
graft-versus-host disease requiring prolonged steroid treatment. Early identification of
endocrine complications can greatly improve the quality of life of long-term survivors
after HSCT.

Purinergic signalling in endocrine organs

Burnstock, G.
Purinergic Signalling 2014; 10 (1), pp. 189-231

There is widespread involvement of purinergic signalling in endocrine biology.
Pituitary cells express P1, P2X and P2Y receptor subtypes to mediate hormone
release. Adenosine 5′-triphosphate (ATP) regulates insulin release in the
pancreas and is involved in the secretion of thyroid hormones. ATP plays a major
role in the synthesis, storage and release of catecholamines from the adrenal gland.
In the ovary purinoceptors mediate gonadotrophin-induced progesterone secretion,
while in the testes, both Sertoli and Leydig cells express purinoceptors that
mediate secretion of oestradiol and testosterone, respectively. ATP released as
a cotransmitter with noradrenaline is involved in activities of the pineal gland
and in the neuroendocrine control of the thymus. In the hypothalamus, ATP and
adenosine stimulate or modulate the release of luteinising hormone-releasing
hormone, as well as arginine-vasopressin and oxytocin. Functionally active P2X
and P2Y receptors have been identified on human placental syncytiotrophoblast
cells and on neuroendocrine cells in the lung, skin, prostate and intestine. Adipocytes
have been recognised recently to have endocrine function involving purinoceptors.

Heroes in endocrinology: Nobel prizes

de Herder, W.W.
Endocrine Connections 2014; 3 (3), pp. R94-R104

The Nobel Prize in Physiology or Medicine was first awarded in 1901. Since then,
the Nobel Prizes in Physiology or Medicine, Chemistry and Physics have been awarded
to at least 33 distinguished researchers who were directly or indirectly involved
in research into the field of endocrinology. This paper reflects on the life histories,
careers and achievements of 11 of them: Frederick G Banting, Roger Guillemin,
Philip S Hench, Bernardo A Houssay, Edward C Kendall, E Theodor Kocher,
John J R Macleod, Tadeus Reichstein, Andrew V Schally, Earl W Sutherland, Jr
and Rosalyn Yalow. All were eminent scientists, distinguished lecturers and
winners of many prizes and awards.

A brief history of great discoveries in pharmacology: In celebration of the centennial
anniversary of the founding of the American Society of Pharmacology and
Experimental Therapeutics
Rubin, R.P.
Pharmacological Reviews 2007; 59 (4), pp. 289-359
http://dx.doi.org:/10.1124/pr.107.70102

Chapter 49 – Primary Hyperparathyroidism and Hyperparathyroid Bone Disease
Lorraine A. Fitzpatrick
Osteoporosis (Second Edition), Volume 2, 2001, Pages 259–269
http://dx.doi.org:/10.1016/B978-012470862-4/50050-7

This chapter reviews the current state of knowledge about primary hyperparathyroidism
(1°HPT) and bone and highlights recent long-term data. Variable degrees of osteopenia
are common in patients having 1°HPT and osteoporosis may be evident at the
diagnosis of 1°HPT. The skeletal deficits are occasionally severe, but usually of
undetermined relationship to the hyperparathyroidism. On average, the decrements
of bone mass suggest only about a doubling of fracture risk, an increment
not discernible in the small studies done to date. The few prospective studies
of fracture risk in 1°HPT were not sufficiently powered to adequately address the
issue. Osteopenia may be worst at primarily cortical sites, which would suggest
a greater risk of appendicular than of spinal crush fractures. Regardless of site or
severity of osteopenia, surgical therapy of 1°HPT causes substantially increased
bone mineral density (BMD) at most sites, on the order of 10 to 12%.
Increases of such magnitude are rarely seen in therapy of osteoporosis by any
other means. Moreover, the increases are larger and may go on for longer periods
than could be accounted for by simple filling in of remodeling space. One
must reason that decrements of bone mass similar to those seen in 1°HPT
increase fracture risk under other circumstances, and assure that restoration of
BMD after parathyroid adenomectomy in hyperparathyroid patients
should substantially reduce fracture risk. Severe bone disease caused by
1°HPT is rare. As a group, hyperparathyroid patients have mildly to moderately
reduced bone mineral density that may be worst for cortical bone, but which
has been observed at all sites. Removal of parathyroid adenomas and restoration
of normal parathyroid function causes substantial, lasting increases of BMD
(averaging 10 to 12%). Gain of bone occurs at all sites, may go on for up to
10 years, and is greatest in patients having the greatest baseline decrements
of BMD.

New aspects of immunoregulation by growth and lactogenic hormones
Berczi, I., Quintanar Stephano, A., Campos, R., Kovacs, K.
Advances in Neuroimmune Biology 2014; 5 (1), pp. 43-60
http://dx.doi.org:/10.3233/NIB-140086

Growth hormone and prolactin maintain adaptive immunity, which incudes cell
mediated immunity, antibody- and autoimmune reactions, maintain thymus
and bone marrow function. Insulin like growth factor-1 participate in the
regulatory action of growth hormone and prolactin. The hypothalamus-pituitary-
adrenal axis stimulates innate immunity and suppresses adaptive immunity.
Dopamine also inhibits adaptive immunity and regulates innate immunity.
Catecholamine’s and corticosteroids support innate immunity and stimulate
suppressor-regulatory T cells, which inhibit adaptive immunity. Adrenalectomy
sensitized mice to Lipid A, which was mediated by exaggerated production
of tumor necrosis factor-alpha, due to the lack of functional hypothalamic
pituitary adrenal axis. Growth and lactogenic hormones share signal
transduction pathways with type I (gamma-c) cytokines. This indicates
functional overlap. The hypothalamic pituitary adrenal axis produces
glucocorticoids, which stimulate innate immunity, and play a primary
role during the acute phase response. Vasopressin supports the acute
phase response, maintains chronic inflammatory reactions and coordinates
healing. Vasopressin maintains immunocompetence during homeostasis
as it stimulates the hypothalamus-pituitary-adrenal axis and also prolactin.
Vasopressin stimulates innate immune cytokine production. Oxytocin is
immunoregulatory. Thyroidectomy in rats suppresses immune function and
thyroxin releases growth hormone and prolactin from transplanted pituitary
grafts in rats and also restores immunocompetence. This indicates that
thyroxin is an indirect immunoregulator. The growth hormone secretagouge,
ghrelin, is immunoregulatory. Dopamine is a neurotransmitter and immuno-regulator. Dopamine has a role in normal immune function and in stress,
inflammatory diseases, schizophrenia, Parkinson disease, Tourette syndrome,
Lupus, Multiple Sclerosis, AIDS, and generalized anxiety syndrome.

Increased frequency of the rs2066853 variant of aryl hydrocarbon receptor gene
in patients with acromegaly
Cannavo, S., Ferrau, F., Ragonese, M., (…), Ruggeri, R.M., Trimarchi, F.
Clinical Endocrinology 2014; 81 (2), pp. 249-253
http://dx.doi.org:/10.1111/cen.12424

Context
Aryl hydrocarbon receptor (AHR) pathway has a key role in cellular detoxification
mechanisms and seems implicated in tumorigenesis. Moreover, polymorphisms
and mutations of AHR gene have been associated with several human and
animal tumours. Although AHR has been found differently expressed in pituitary
adenomas, AHR gene mutation status has never been investigated in acromegalic
patients. Design In this study, we evaluated patients with apparently sporadic GH-secreting pituitary adenoma for AHR gene variants.
Patients and Methods
Seventy patients with sporadic GH-secreting pituitary adenoma (M = 27, age
59·1 ± 1·6 years) and 157 sex- and age-atched controls were enrolled in the
study. In all patients and controls, the exons 1, 2, 3, 5 and 10 of AHR gene were
evaluated for nucleotide variants by sequencing analysis.
Results
The rs2066853 polymorphism was identified in the exon 10 of 18/70 acromegalic
patients and 9/157 healthy subjects (25·7 vs. 5·7%, χ2 = 18·98 P < 0·0001), in
homozygosis in one patient and in heterozygosis in the other 17 and in the
9 healthy subjects. Moreover, a heterozygous rs4986826 variant in exon 10
was identified in a patient with heterozygous rs2066853 polymorphism, and
in the patient with homozygous rs2066853 variant. This second polymorphism
was not detected in the control group. Patients with rs2066853 polymorphism
showed increased IGF-1 ULN (P < 0·05) and prevalence of cavernous
sinus invasion (P = 0·05), thyroid (P = 0·02), bladder (P = 0·0001) or
lymphohematopoietic (P < 0·05) tumours.
Conclusions
AHR gene rs2066853 polymorphism is significantly more frequent in
acromegalic patients than in healthy subjects and is associated with
increased disease aggressivity. Moreover, the rs4986826 variant was
detected in few patients with rs2066853 polymorphism, but its role is
to be cleared.

Current knowledge of D-aspartate in glandular tissues
Hunn, B.H.M., Martin, W.G., Simpson Jr., S., Mclean, C.A.
Clinical Endocrinology 2014; 81 (2), pp. 249-253
http://dx.doi.org:/10.1111/cen.12424

Context
Aryl hydrocarbon receptor (AHR) pathway has a key role in cellular
detoxification mechanisms and seems implicated in tumorigenesis.
Moreover, polymorphisms and mutations of AHR gene have been
associated with several human and animal tumours. Although AHR has
been found differently expressed in pituitary adenomas, AHR gene mutation
status has never been investigated in acromegalic patients.
Design
In this study, we evaluated patients with apparently sporadic GH-secreting
pituitary adenoma for AHR gene variants.
Patients and Methods
Seventy patients with sporadic GH-secreting pituitary adenoma (M = 27,
age 59·1 ± 1·6 years) and 157 sex- and age-atched controls were enrolled
in the study. In all patients and controls, the exons 1, 2, 3, 5 and 10 of
AHR gene were evaluated for nucleotide variants by sequencing analysis.
Results
The rs2066853 polymorphism was identified in the exon 10 of 18/70
acromegalic patients and 9/157 healthy subjects (25·7 vs. 5·7%, χ2 = 18·98
P < 0·0001), in homozygosis in one patient and in heterozygosis in the other
17 and in the 9 healthy subjects. Moreover, a heterozygous rs4986826 variant
in exon 10 was identified in a patient with heterozygous rs2066853
polymorphism, and in the patient with homozygous rs2066853 variant.
This second polymorphism was not detected in the control group. Patients
with rs2066853 polymorphism  showed increased IGF-1 ULN (P < 0·05)
and prevalence of cavernous sinus invasion (P = 0·05), thyroid (P = 0·02),
bladder (P = 0·0001) or lymphohematopoietic (P < 0·05) tumours.
Conclusions
AHR gene rs2066853 polymorphism is significantly more frequent in
acromegalic patients than in healthy subjects and is associated with
increased disease aggressivity. Moreover, the rs4986826 variant was
detected in few patients with rs2066853 polymorphism, but its role is
to be cleared.

Autophagy in the endocrine glands
Weckman, A., Di Ieva, A., Rotondo, F., (…), Kovacs, K., Cusimano
Journal of Molecular Endocrinology 2013; 52 (2), pp. R151-R163
http://dx.doi.org:/10.1530/JME-13-0241

Autophagy is an important cellular process involving the degradation of
intracellular components. Its regulation is complex and while there are
many methods available, there is currently no single effective way of
detecting and monitoring autophagy. It has several cellular functions
that are conserved throughout the body, as well as a variety of different
physiological roles depending on the context of its occurrence in the
body. Autophagy is also involved in the pathology of a wide range of
diseases. Within the endocrine system, autophagy has both its traditional
conserved functions and specific functions. In the endocrine glands,
autophagy plays a critical role in controlling intracellular hormone levels.
In peptide-secreting cells of glands such as the pituitary gland, crinophagy,
a specific form of autophagy, targets the secretory granules to control the
levels of stored hormone. In steroid-secreting cells of glands such as the
testes and adrenal gland, autophagy targets the steroid-producing organelles.
The dysregulation of autophagy in the endocrine glands leads to several
different endocrine diseases such as diabetes and infertility. This review
aims to clarify the known roles of autophagy in the physiology of the
endocrine system, as well as in various endocrine diseases.

Insm1 controls development of pituitary endocrine cells and requires a SNAG
domain for function and for recruitment of histone-modifying factors
Welcker, J.E., Hernandez-Miranda, L.R., Paul, F.E., (…), Selbach, M., Birchmeier, C.
Development (Cambridge) 2013; 140 (24), pp. 4947-4958
http://dx.doi.org:/10.1242/dev.097642

The Insm1 gene encodes a zinc finger factor expressed in many endocrine organs.
We show here that Insm1 is required for differentiation of all endocrine cells in the
pituitary. Thus, in Insm1 mutant mice, hormones characteristic of the different
pituitary cell types (thyroid-stimulating hormone, follicle-stimulating hormone,
melanocyte-stimulating hormone, adrenocorticotrope hormone, growth hormone
and prolactin) are absent or produced at markedly reduced levels. This differentiation
deficit is accompanied by upregulated expression of components of the Notch
signaling pathway, and by prolonged expression of progenitor markers, such
as Sox2. Furthermore, skeletal muscle-specific genes are ectopically expressed
in endocrine cells, indicating that Insm1 participates in the repression of an
inappropriate gene expression program. Because Insm1 is also essential for
differentiation of endocrine cells in the pancreas, intestine and adrenal gland,
it is emerging as a transcription factor that acts in a pan-endocrine manner.
The Insm1 factor contains a SNAG domain at its N-terminus, and we show
here that the SNAG domain recruits histone-modifying factors (Kdm1a, Hdac1/2
and Rcor1-3) and other proteins implicated in transcriptional regulation (Hmg20a/b
and Gse1). Deletion of sequences encoding the SNAG domain in mice disrupted
differentiation of pituitary endocrine cells, and resulted in an upregulated expression
of components of the Notch signaling pathway and ectopic expression of skeletal
muscle-specific genes. Our work demonstrates that Insm1 acts in the epigenetic
and transcriptional network that controls differentiation of endocrine cells in the
anterior pituitary gland, and that it requires the SNAG domain to exert
this function in vivo.
Neuromedin B stimulates the hypothalamic–pituitary–gonadal axis in male rats

C.K. Boughton, S.A. Patel, E.L. Thompson, M. Patterson, A.E. Curtis, A. Amina, et al.
Regulatory Peptides 187 (2013) 6–11
http://dx.doi.org/10.1016/j.regpep.2013.10.002

Neuromedin B (NMB) is a highly conserved bombesin-related peptide found in mammals. NMB mRNA is detected in the central nervous system(CNS) and is highly expressed in the rat hypothalamus, in particular the medial preoptic area and the arcuate nucleus. The mammalian bombesin family of receptors consists of three closely related G protein coupled receptors, BB1, BB2 and BB3. The BB1 receptor subtype has the highest affinity for NMB. NMB has well documented roles in the regulation of the thyroid axis and the stress axis in rats. However, there is little available data regarding the role of NMB in the regulation of the hypothalamic–pituitary–gonadal (HPG) axis. It is known that the NMB receptor is expressed in immortalized gonadotrophin releasing hormone (GnRH) releasing GT1-7 cells and murine forebrain GnRH neurons, and that anterior pituitary NMB immunoreactivity is altered by changes in the sex steroid environment.
The objective of these studies was thus to further investigate the effects of NMB on the HPG axis. Intracerebroventricular (ICV) administration of NMB (10nmol) to adult male rats significantly increased plasma luteinizing hormone (LH) levels 30min after injection (plasma LH ng/ml; saline 0.69±0.07, 10nmol NMB1.33± 0.17, P b 0.01). In vitro, NMB stimulated GnRH release from hypothalamic explants from male rats and from hypothalamic GT1-7 cells.
NMB had no significant effect on LH release from anterior pituitary explants from male rats, or from pituitary LβT2 cells in vitro. These results suggest a previously unreported role for NMB in the stimulation of the HPG axis via hypothalamic GnRH. Further work is now required to determine the receptor mediating the effects of NMB on the reproductive axis and the physiological role of NMB in reproduction.

Thyroid and Pituitary

TGFβ2 regulates hypothalamic Trh expression through the TGFβ inducible early gene-1 (TIEG1) during fetal development

M Molecular and Cellular Endocrinology 400 (2015) 129–139 Martínez-Armenta, SD de León-Guerrero, A Catalán, L Alvarez-Arellano, et al.
http://dx.doi.org/10.1016/j.mce.2014.10.021

The hypothalamus regulates the homeostasis of the organism by controlling hormone secretion from the pituitary. The molecular mechanisms that regulate the differentiation of the hypothalamic thyrotropin releasing hormone (TRH) phenotype are poorly understood. We have previously shown that Klf10 or TGFβ inducible early gene-1 (TIEG1) is enriched in fetal hypothalamic TRH neurons. Here, we show that expression of TGFβ isoforms (1-3) and both TGFβ receptors (TβRI and II) occurs in the hypothalamus concomitantly with the establishment of TRH neurons during late embryonic development. TGFβ2 induces Trh expression via a TIEG1 dependent mechanism. TIEG1 regulates Trh expression through an evolutionary conserved GC rich sequence on the Trh promoter. Finally, in mice deficient in TIEG1, Trh expression is lower than in wild type animals at embryonic day 17. These results indicate that TGFβ signaling, through the upregulation of TIEG1, plays an important role in the establishment of Trh expression in the embryonic hypothalamus.

Gonadotropic Hormone

The essence of female–male physiological dimorphism: Differential Ca2+-homeostasis enabled by the interplay between farnesol-like endogenous sesquiterpenoids and sex-steroids? The Calcigender paradigm

Arnold De Loof
General and Comparative Endocrinology 211 (2015) 131–146
http://dx.doi.org/10.1016/j.ygcen.2014.12.003

Ca2+ is the most omnipresent pollutant on earth, in higher concentrations a real threat to all living cells. When [Ca2+]i rises above 100 nM (=resting level), excess Ca2+ needs to be confined in the SER and mitochondria, or extruded by the different Ca2+-ATPases. The evolutionary origin of eggs and sperm cells has a crucial, yet often overlooked link with Ca2+-homeostasis. Because there is no goal whatsoever in evolution, gametes did neither originate ‘‘with the purpose’’ of generating a progeny nor of increasing fitness by introducing meiosis. The explanation may simply be that females ‘‘invented the trick’’ to extrude eggs from their body as an escape strategy for getting rid of toxic excess Ca2+ resulting from a sex-hormone driven increased influx into particular cells and tissues. The production of Ca2+-rich milk, seminal fluid in males and all secreted proteins by eukaryotic cells may be similarly explained. This view necessitates an upgrade of the role of the RER-Golgi system in extruding Ca2+. In the context of insect metamorphosis, it has recently been (re)discovered that (some isoforms of) Ca2+-ATPases act as membrane receptors for some types of lipophilic ligands, in particular for endogenous farnesol-like sesquiterpenoids (FLS) and, perhaps, for some steroid hormones as well. A novel paradigm, tentatively named ‘‘Calcigender’’ emerges. Its essence is: gender-specific physiotypes ensue from differential Ca2+-homeostasis enabled by genetic differences, farnesol/FLS and sex hormones. Apparently the body of reproducing females gets temporarily more poisoned by Ca2+ than the male one, a selective benefit rather than a disadvantage.

Kisspeptin induces expression of gonadotropin-releasing hormone receptor in GnRH-producing GT1–7 cells overexpressing G protein-coupled receptor 54

U Sukhbaatar, H Kanasaki, T Mijiddorj, Aki Oride, Ki Miyazaki
General and Comparative Endocrinology 194 (2013) 94–101
http://dx.doi.org/10.1016/j.ygcen.2013.09.002

Kisspeptin signaling through its receptor is crucial for many reproductive functions. However, the molecular mechanisms and biomedical significance of the regulation of GnRH neurons by kisspeptin have not been adequately elucidated.
In the present study, we found that kisspeptin increases GnRH receptor (GnRHR) expression in a GnRH-producing cell line (GT1–7). Because cellular activity of G protein-coupled receptor 54 (GPR54) and GnRHR was limited in GT1–7 cells, we overexpressed these receptors to clarify receptor function.
Using luciferase reporter constructs, the activity of both the serum response element (Sre) promoter, a target for extracellular signal-regulated kinase (ERK), and the cyclic AMP (cAMP) response element (Cre) promoter were increased by kisspeptin. Although GnRH increased Sre promoter activity, the Cre promoter was not significantly activated by GnRH. Kisspeptin, but not GnRH, increased cAMP accumulation in these cells. Kisspeptin also increased the transcriptional activity of GnRHR; however, the effect of GnRH on the GnRHR promoter was limited and not significant. Transfection of GT1–7 cells with constitutively active MEK kinase (MEKK) and protein kinase A (PKA) increased GnRHR expression. In addition, GnRHR expression was further increased by co-overexpression of MEKK and PKA. The Cre promoter, but not the Sre promoter, was also further activated by co-overexpression of MEKK and PKA. GnRH significantly increased the activity of the GnRHR promoter in the presence of cAMP.
The present findings suggest that kisspeptin is a potent stimulator of GnRHR expression in GnRH-producing neurons in association with ERK and the cAMP/PKA pathways

Role of leptin in the regulation of sterol/steroid biosynthesis in goose granulosa cells

Shenqiang Hu, Chao Gan, Rui Wen, Qihai Xiao, Hua Gou, Hehe Liu, et al.
Theriogenology 82 (2014) 677–685
http://dx.doi.org/10.1016/j.theriogenology.2014.05.025

Leptin is critical for reproductive endocrinology. The aim of this study is to assess the expression patterns of leptin receptor (Lepr) during ovarian follicle development and to reveal the mechanism by which leptin affects steroid hormone secretion in goose granulosa cells. Transcripts of Lepr were ubiquitous in all tested tissues, with pituitary and adrenal glands being the predominant sites. Goose ovarian follicles were divided into several groups by diameter including prehierarchical (4 to 6, 6 to 8, and 8 to 10 mm) and hierarchical (F5–F1) follicles. Lepr gene expression was significantly higher in granulosa cells than in theca cells from follicles of 4 to 8 mm in diameter. Expression of Lepr in granulosa cells decreased gradually as follicles developed, with fluctuating expression in F5 and F3 follicles. Lepr mRNA in theca cells underwent a slight decrease from the 6- to 8-mm cohorts to F5 follicle and then exhibited a transient increase and declined later. In vitro experiments in cultured goose granulosa cells showed that estradiol release was significantly stimulated, whereas progesterone increased slightly and testosterone decreased dramatically after leptin treatment. In accordance with the data for steroids, expression of Lepr, Srebp1, Cyp51, StAR, and Cyp19a1 were induced by the addition of leptin, and the concomitant changes in Hmgcs1, Dhcr24, Cyp11a1, 17b-hsd, Cyp17, and 3b-hsd gene expression were seen. These results suggested that leptin is involved in the development of goose ovarian follicles, and leptin’s effect on steroid hormone secretion could be due to altered sterol/steroidogenic gene expression via interaction with its receptor.

Progesterone and 17[1]-estradiol regulate expression ofnesfatin-1/NUCB2 in mouse pituitary gland

Yiwa Chung, Jinhee Kim, Eunji Im, Heejeong Kim, Hyunwon Yang
Peptides 63 (2015) 4–9
http://dx.doi.org/10.1016/j.peptides.2014.10.011

tNesfatin-1 was first shown to be involved in the control of appetite and energy metabolism in the hypo-thalamus. Many recent reports have shown nesfatin-1 expression in various tissues including the pituitary gland, but its expression and regulation mechanisms in the pituitary gland are unclear. Therefore, first, we investigated the mRNA and protein expression of nesfatin-1 in the pituitary using qRT-PCR and Western blotting, respectively. Expression of NUCB2 mRNA and nesfatin-1 protein was higher in the pituitary gland than in other organs, and nesfatin-1 protein was localized in many cells in the anterior pituitary gland. Next, we investigated whether NUCB2 mRNA expression in the pituitary gland was regulated by sex steroid hormones secreted by the ovary. Mice were ovariectomized and injected with progesterone (P4) and 17[1]-estradiol (E2). The expression of NUCB2 in the pituitary gland was dramatically decreased after ovariectomy and increased with injection of P4 and E2, respectively. The in vitro experiment to elucidate the direct effect of P4 and E2 on NUCB2 mRNA expression showed NUCB2 mRNA expression was significantly increased with E2 and decreased with P4 alone and P4 plus E2 in cultured pituitary tissue. The present study demonstrated that nesfatin-1/NUCB2 was highly expressed in the mouse pituitary and was regulated by P4 and E2. These data suggest that reproductive-endocrine regulation through hypothalamus–pituitary–ovary axis may contribute to nesfatin-1/NUCB2 expression in the pituitary gland.

The role of TGF-β/Smad signaling in dopamine agonist-resistant prolactinomas
Zhenye Li, Qian Liu1, Chuzhong Li, Xuyi Zong, Jiwei Bai, YoutuWu, et al.
Molecular and Cellular Endocrinology 402 (2015) 64–71
http://dx.doi.org/10.1016/j.mce.2014.12.024

Background: Prolactinomas are the most common secretory pituitary adenomas. The first line of treatment involves dopamine agonists (DAs); however, a subset of patients is resistant to such therapy. Recent studies suggest that dopamine can up-regulate TGF-β1 synthesis in rat pituitary lactotrophs whereas estradiol down-regulates TGF-β1. To date, the role of TGF-β/Smad signaling in DAs-resistant prolactinomas has not been explored.
Methods: High-content screening (HCS) techniques, qRT-PCR,Western blot, immunofluorescence and ELISA, were performed to determine the role of TGF-β/Smad signaling in DAs-resistant prolactinomas.
Results: We reported a significant down-regulation of TGF-β/Smad signaling cascade in DAs-resistant prolactinomas compared to normal human anterior pituitaries. Following treatment with TGF-β1, the dopamine agonist, bromocriptine, and the estrogen antagonist (ER), fulvestrant in GH3 cells, we found that TGF-β1 and fulvestrant caused significant cytotoxicity in a dose- and time-dependent manner and activated Smad3 was detected following exposure to TGF-β1 and fulvestrant. In addition, treating GH3 cells with fulvestrant increased active TGF-β1 levels and decreased PRL levels in a dose-dependent manner.
Conclusion: TGF-β/Smad signaling pathway may play an important role in DA-resistant prolactinomas and has the potential to be a viable target for the diagnosis and treatment of prolactinomas, particularly in patients who are resistant to Das.

Pituitary adenylate cyclase-activating polypeptide (PACAP) increases expression of the gonadotropin-releasing hormone (GnRH) receptor in GnRH-producing GT1-7 cells overexpressing PACAP type I receptor

Haruhiko Kanasaki, T Mijiddorj, U Sukhbaatar, Aki Oride, K Miyazaki
General and Comparative Endocrinology 193 (2013) 95–102
http://dx.doi.org/10.1016/j.ygcen.2013.07.013

The present study demonstrates the action of pituitary adenylate cyclase-activating polypeptide (PACAP) on gonadotropin-releasing hormone (GnRH)-producing neuronal cells, GT1-7. Because we found the expression levels of PACAP type 1 receptor (PAC1R) to be low in these cells, we transfected them with PAC1R expression vector and observed the outcome. PACAP increased the activity of the serum response element (Sre) promoter, a target of extracellular signal-regulated kinase (ERK), as well as the cAMP response element (Cre) promoter in GT1-7 cells overexpressing PAC1R. We also observed ERK phosphorylation and cAMP accumulation upon PACAP stimulation. PACAP stimulated the promoter activity of GnRH receptor (GnRHR) with increasing levels of GnRHR proteins. Notably, the increase in GnRHR promoter activity from kisspeptin was potentiated in the presence of PACAP. A similar increasing effect of PACAP on the action of kisspeptin was observed for Cre promoter activity. On the other hand, the Sre promoter activated by kisspeptin was inhibited by co-treatment with kisspeptin and PACAP. Likewise, kisspeptin-increased GnRHR promoter activity and Cre promoter activity were both potentiated in the presence of cAMP, whereas the Sre promoter activated by kisspeptin was inhibited in the presence of cAMP. Our observations show that PACAP increases GnRHR expression and stimulates kisspeptin’s effect on GnRHR expression in association with the cAMP/PKA signaling pathway in GT1-7 cells overexpressing PAC1R. In addition, PACAP was shown to have an inhibitory effect on ERK-mediated kisspeptin action.

PACAP modulates GnRH signaling in gonadotropes

Lisa M. Halvorson
Molecular and Cellular Endocrinology 385 (2014) 45–55
http://dx.doi.org/10.1016/j.mce.2013.09.029

Hypothalamic gonadotropin-releasing hormone is known to be critical for normal gonadotropin biosynthesis and secretion by the gonadotrope cells of the anterior pituitary gland. Additional regulation is provided by gonadal steroid feedback as well as by intrapituitary factors, such as activin and follistatin. Less well-appreciated is the role of pituitary adenylate-cyclase activating polypeptide (PACAP) as both a hypothalamic–pituitary releasing factor as well as an autocrine–paracrine factor within the pituitary. PACAP regulates gonadotropin expression alone and through modulation of GnRH responsiveness achieved by increases in GnRH receptor expression and interactions at the level of intracellular signaling pathways. In addition to direct effects on the gonadotrope, PACAP stimulates follistatin secretion by the folliculostellate cells and thereby contributes to differential expression of the gonadotropin subunits. Conversely, GnRH augments the ability of PACAP to regulate gonadotrope function by increasing pituitary PACAP and PACAP receptor expression. This review will summarize the current understanding of the mechanisms by which PACAP modulates gonadotrope function, with a focus on interactions with GnRH.

Grass carp prolactin: Molecular cloning, tissue expression, intrapituitary autoregulation by prolactin and paracrine regulation by growth hormone and luteinizing hormone

Chengyuan Lin, Xue Jiang, Guangfu Hu, W.K.W. Ko, A.O.L.Wong
Molecular and Cellular Endocrinology 399 (2015) 267–283
http://dx.doi.org/10.1016/j.mce.2014.0.00

Prolactin (PRL), a pituitary hormone with diverse functions, is well-documented to be under the control of both hypothalamic and peripheral signals. Intrapituitary modulation of PRL expression via autocrine/paracrine mechanisms has also been reported, but similar information is still lacking in lower vertebrates. To shed light on autocrine/paracrine regulation of PRL in fish model, grass carp PRL was cloned and its expression in the carp pituitary has been confirmed. In grass carp pituitary cells, local secretion of PRL could suppress PRL release with concurrent rises in PRL production and mRNA levels. Paracrine stimulation by growth hormone (GH) was found to up-regulate PRL secretion, PRL production and PRL transcript expression, whereas the opposite was true for the local actions of luteinizing hormone (LH). Apparently, local interactions of PRL, GH and LH via autocrine/paracrine mechanisms could modify PRL production in carp pituitary cells through differential regulation of PRL mRNA stability and gene transcription.

Gonadotropin inhibitory hormone (GnIH) as a regulator of gonadotropes

Iain J. Clarke, Helena C. Parkington
Molecular and Cellular Endocrinology 385 (2014) 36–44
http://dx.doi.org/10.1016/j.mce.2013.08.017

Gonadotropin inhibitory hormone (GnIH) has emerged as a negative regulator of gonadotrope function in a range of species. In rodents, such as rats and mice, GnIH exerts influence upon GnRH cells within the brain. In other species, however, the peptide is secreted into hypophysial portal blood to act on pituitary gonadotropes. In particular, a series of studies in sheep have demonstrated potent actions at the level of the pituitary gland to counteract the function of GnRH in terms of the synthesis and secretion of gonadotropins. This review focuses on the action of GnIH at the level of the gonadotrope.

GPR30 mediates anorectic estrogen-induced STAT3 signaling in the hypothalamus

Obin Kwona,, Eun Seok Kang, Insook Kim, Sora Shina, Mijung Kima, et al.
Metabolism Clinical Exper 2014: 63: 1455–1461
http://dx.doi.org/10.1016/j.metabol.2014.07.015

Objective. Estrogen plays an important role in the control of energy balance in the hypothalamus. Leptin-independent STAT3 activation (i.e., tyrosine705-phosphorylation of STAT3, pSTAT3) in the hypothalamus is hypothesized as the primary mechanism of the estrogen-induced anorexic response. However, the type of estrogen receptor that mediates this regulation is unknown. We investigated the role of the G protein-coupled receptor 30 (GPR30) in estradiol (E2)-induced STAT3 activation in the hypothalamus.
Materials/methods. Regulation of STAT3 activation by E2, G-1, a specific agonist of GPR30 and G-15, a specific antagonist of GPR30 was analyzed in vitro and in vivo. Effect of GPR30 activation on eating behavior was analyzed in vivo.
Results. E2 stimulated pSTAT3 in cells expressing GPR30, but not expressing estrogen receptor ERα and ERβ. G-1 induced pSTAT3, and G-15 inhibited E2-induced pSTAT3 in primary cultures of hypothalamic neurons. A cerebroventricular injection of G-1 increased pSTAT3 in the arcuate nucleus of mice, which was associated with a decrease in food intake and body weight gain.
Conclusions. These results suggest that GPR30 is the estrogen receptor that mediates the anorectic effect of estrogen through the STAT3 pathway in the hypothalamus.

Leptin influences estrogen metabolism and accelerates prostate cell proliferation

CN Habib, AM Al-Abd, Mai F. Tolba, AE Khalifa, Alaa Khedr, et al.
Life Sciences 121 (2015) 10–15
http://dx.doi.org/10.1016/j.lfs.2014.11.007

Aim: The present study was designed to investigate the effect of leptin on estrogen metabolism in prostatic cells.
Main methods: Malignant (PC-3) and benign (BPH-1) human prostate cells were treated with 17-β-hydroxyestradiol (1 μM) alone or in combination with leptin (0.4, 4, 40 ng/ml) for 72 h. Cell proliferation assay, immunocytochemical staining of estrogen receptor (ER), liquid chromatography–tandem mass spectrometry method (LC–MS) and semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) were used.
Key findings: Cell proliferation assay demonstrated that leptin caused significant growth potentiation in both cells. Immunocytochemical staining showed that leptin significantly increased the expression of ER-α and decreased that of ER-β in PC-3 cells. LC–MS method revealed that leptin increased the concentration 4-hydroxyestrone and/or decreased that of 2-methoxyestradiol, 4-methoxyestradiol and 2-methoxyestrone. Interestingly, RT-PCR showed that leptin significantly up-regulated the expression of aromatase and cytochrome P450 1B1 (CYP1B1) enzymes; however down-regulated the expression of catechol-o-methyltransferase (COMT) enzyme.
Significance: These data indicate that leptin-induced proliferative effect in prostate cells might be partly attributed to estrogen metabolism. Thus, leptin might be a novel target for therapeutic intervention in prostatic disorders.

Ovariectomy in young prepubertal dairy heifers causes complete suppression of mammary progesterone receptors

B.T. Velayudhan, B.P. Huderson, S.E. Ellis, C.L. Parsons, R.C. Hovey, et al.
Domestic Animal Endocrinology 51 (2015) 8–18
http://dx.doi.org/10.1016/j.domaniend.2014.10.002

Mammary growth and development depends on ovarian steroids and particularly interaction of estrogen and progesterone with their intracellular receptors. The objectives of this study were to determine the effect of ovariectomy on the expression of protein and messenger RNA for estrogen receptor-alpha (ESR1) and progesterone receptor (PGR) and their relation to mammary ductal development and cell proliferation. Prepubertal Holstein heifers 2, 3, or 4 mo of age were randomly assigned to one of 2 treatments, ovariectomized (OVX; n ¼ 8) or sham operated (INT; n ¼ 12). Mammary parenchymal (PAR) tissue samples were harvested 30 d after surgery. Localization and quantitation of ESR1 and PGR in PAR were determined by immunohistochemistry and quantitative multispectral imaging. Relative messenger RNA expression of ESR1 and PGR in PAR was measured by quantitative real time polymerase chain reaction. We observed the complete absence of PGR-positive epithelial cell nuclei and reduced PGR transcript abundance in mammary parenchyma of OVX heifers. The percent of epithelial cells expressing ESR1 did not differ by treatment but was decreased with age. However, average intensity of ESR1 expression per cell was reduced in OVX heifers. The abundance of Ki67 labeled epithelial cells and stromal cells was reduced after ovariectomy. These data suggest that reduced mammary development after ovariectomy may be mediated by loss of PGR expression and reduced ESR1 expression in positive cells. A presumptive relationship with ovarian-derived circulating estradiol remains unresolved, but data suggest other ovarian-derived agents may play a role. Use of specific antagonists to manipulate expression or action of PGR and ESR1 receptors should provide direct evidence for roles of these receptors in prepubertal bovine mammary development.

Growth Hormone and IGF 1..2

IGF1R blockade with ganitumab results in systemic effects on the GH-IGF axis in mice

Moody, G., Beltran, P.J., Mitchell, P., (…), Cohen, P., Calzone, F.J.
2014 Journal of Endocrinology 221 (1), pp. 145-155

Ganitumab is a fully human MAB to the human type 1 IGF receptor (IGF1R). Binding assays showed that ganitumab recognized murine IGF1R with sub-nanomolar affinity (KDZ0.22 nM) and inhibited the interaction of murine IGF1R with IGF1 and IGF2. Ganitumab inhibited IGF1-induced activation of IGF1R in murine lungs and CT26 murine colon carcinoma cells and tumors. Addition of ganitumab to 5-fluorouracil resulted in enhanced inhibition of tumor growth in the CT26 model. Pharmacological intervention with ganitumab in naïve nude mice resulted in a number of physiological changes described previously in animals with targeted deletions of Igf1 and Igf1r, including inhibition of weight gain, reduced glucose tolerance and significant increase in serum levels of GH, IGF1 and IGFBP3. Flow cytometric analysis identified GR1/CD11b-positive cells as the highest IGF1R-expressing cells in murine peripheral blood. Administration of ganitumab led to a dose-dependent, reversible decrease in the number of peripheral neutrophils with no effect on erythrocytes or platelets. These findings indicate that acute IGF availability for its receptor plays a critical role in physiological growth, glucose metabolism and neutrophil physiology and support the presence of a pituitary IGF1R-driven negative feedback loop that tightly regulates serum IGF1 levels through Gh signaling.

Determinants of GH resistance in malnutrition

Fazeli, P.K., Klibanski, A.

2014 Journal of Endocrinology 220 (3), pp. R57-R65

States of undernutrition are characterized by GH resistance. Decreased total energy intake, as well as isolated protein-calorie malnutrition and isolated nutrient deficiencies, result in elevated GH levels and low levels of IGF1. We review various states of malnutrition and a disease state characterized by chronic undernutrition – anorexia nervosa – and discuss possible mechanisms contributing to the state of GH resistance, including fibroblast growth factor 21 and Sirtuin 1. We conclude by examining the hypothesis that GH resistance is an adaptive response to states of undernutrition, in order to maintain euglycemia and preserve energy.

Hepatic Hedgehog signaling contributes to the regulation of IGF1 and IGFBP1 serum levels

Matz-Soja, M., Aleithe, S., Marbach, E., (…), Kratzsch, J., Gebhardt, R.
2014 Cell Communication and Signaling 12 (1), 11

Background: Hedgehog signaling plays an important role in embryonic development, organogenesis and cancer. In the adult liver, Hedgehog signaling in non-parenchymal cells has been found to play a role in certain disease states such as fibrosis and cirrhosis. However, whether the Hedgehog pathway is active in mature healthy hepatocytes and is of significance to liver function are controversial.
Findings. Two types of mice with distinct conditional hepatic deletion of the Smoothened gene, an essential co-receptor protein of the Hedgehog pathway, were generated for investigating the role of Hedgehog signaling in mature hepatocytes. The knockout animals (KO) were inconspicuous and healthy with no changes in serum transaminases, but showed a slower weight gain. The liver was smaller, but presented a normal architecture and cellular composition. By quantitative RT-PCR the downregulation of the expression of Indian hedgehog (Ihh) and the Gli3 transcription factor could be demonstrated in healthy mature hepatocytes from these mice, whereas Patched1 was upregulated. Strong alterations in gene expression were also observed for the IGF axis. While expression of Igf1 was downregulated, that of Igfbp1 was upregulated in the livers of both genders. Corresponding changes in the serum levels of both proteins could be detected by ELISA. By activating and inhibiting the transcriptional output of Hedgehog signaling in cultured hepatocytes through siRNAs against Ptch1 and Gli3, respectively, in combination with a ChIP assay evidence was collected indicating that Igf1 expression is directly dependent on the activator function of Gli3. In contrast, the mRNA level of Igfbp1 appears to be controlled through the repressor function of Gli3, while that of Igfbp2 and Igfbp3 did not change. Interestingly, body weight of the transgenic mice correlated well with IGF-I levels in both genders and also with IGFBP-1 levels in females, whereas it did not correlate with serum growth hormone levels.
Conclusions: Our results demonstrate for the first time that Hedgehog signaling is active in healthy mature mouse hepatocytes and that it has considerable importance for IGF-I homeostasis in the circulation. These findings may have various implications for mouse physiology including the regulation of body weight and size, glucose homeostasis and reproductive capacity.

How IGF-1 activates its receptor

Jennifer M Kavran, JM McCabe, PO Byrne, MK Connacher, et al.
eLife 2014;10.7554/eLife.03772 http://dx.doi.org/10.7554/eLife.03772

The Type I Insulin-like Growth Factor Receptor (IGF1R) is involved in growth and  survival of normal and neoplastic cells. A ligand-dependent conformational change is thought to regulate IGF1R activity, but the nature of this change is unclear. We point out an underappreciated dimer in the crystal structure of the related Insulin Receptor (IR) with Insulin bound that allows direct comparison with unliganded IR and suggests a mechanism by which ligand regulates IR/IGF1R activity.
We test this mechanism in a series of biochemical and biophysical assays and find the IGF1R ectodomain maintains an autoinhibited state in which the TMs are held apart. Ligand binding releases this constraint, allowing TM association and unleashing an intrinsic propensity of the intracellular regions to autophosphorylate. Enzymatic studies of full-length and kinase containing fragments show phosphorylated IGF1R is fully active independent of ligand and the extracellular-TM regions.
The key step triggered by ligand binding is thus autophosphorylation.

Molecular evolution of growth hormone and insulin-like growth factor 1 receptors in long-lived, small-bodied mammals

Kalina T.J. Davies, Georgia Tsagkogeorga, Nigel C. Bennett, Liliana M. Dávalos, et al.
Gene 549 (2014) 228–236 http://dx.doi.org/10.1016/j.gene.2014.07.061

Mammals typically display a robust positive relationship between lifespan and body size. Two groups that deviate markedly from this pattern are bats and African mole-rats, with members of both groups being extremely long-lived given their body size, with the maximum documented lifespan for many species exceeding 20 years.
A recent genomics study of the exceptionally long-lived Brandt’s bat, Myotis brandtii (41 years), suggested that its longevity and small body size may be at least partly attributed to key amino acid substitutions in the transmembrane domains of the receptors of growth hormone (GH) and insulin-like growth factor 1 (IGF1). However, whereas elevated longevity is likely to be common across all 19 bat families, the reported amino acid substitutions were only observed in two closely related bat families.
To test the hypothesis that an altered GH/IGF1 axis relates to the longevity of African mole-rats and bats, we compared and analyzed the homologous coding gene sequences in genomic and transcriptomic data from 26 bat species, five mole-rats and 38 outgroup species.
Phylogenetic analyses of both genes recovered the majority of nodes in the currently accepted species tree with high support. Compared to other clades, such as primates and carnivores, the bats and rodents had longer branch lengths. The single 24 amino acid transmembrane domain of IGF1Rwas found to be more conserved across mammals compared to that of GHR. Within bats, considerable variation in the transmembrane domain of GHR was found, including a previously unreported deletion in Emballon uridae. The transmembrane domains of rodents were found to be more conserved, with mole-rats lacking uniquely conserved amino acid substitutions. Molecular evolutionary analyses showed that both genes were under purifying selection in bats and mole-rats.
Our findings suggest that while the previously documented mutations may confer some additional lifespan to Myotis bats, other, as yet unknown, genetic differences are likely to account for the long lifespans observed in many bat and mole-rat species.

Treatment with N- And C-terminal peptides of parathyroid hormone-related
protein partly compensate the skeletal abnormalities in IGF-I deficient mice

Rodríguez-de La Rosa, L., López-Herradón, A., Portal-Núñez, S., (…), Varela-Nieto, I., Esbrit, P.
2014 PLoS ONE 9 (2), e87536

Insulin-like growth factor-I (IGF-I) deficiency causes growth delay, and IGF-I has been shown to partially mediate bone anabolism by parathyroid hormone (PTH). PTH-related protein (PTHrP) is abundant in bone, and has osteogenic features by poorly defined mechanisms. We here examined the capacity of PTHrP (1-36) and PTHrP (107-111) (osteostatin) to reverse the skeletal alterations associated with IGF-I deficiency. Igf1-null mice and their wild type littermates were treated with each PTHrP peptide (80 mg/Kg/every other day/2 weeks; 2 males and 4 females for each genotype) or saline vehicle (3 males and 3 females for each genotype). We found that treatment with either PTHrP peptide ameliorated trabecular structure in the femur in both genotypes. However, these peptides were ineffective in normalizing the altered cortical structure at this bone site in Igf1-null mice. An aberrant gene expression of factors associated with osteoblast differentiation and function, namely runx2, osteoprotegerin/ receptor activator of NF-?B ligand ratio, Wnt3a, cyclin D1, connexin 43, catalase and Gadd45, as well as in osteocyte sclerostin, was found in the long bones of Igf1-null mice. These mice also displayed a lower amount of trabecular osteoblasts and osteoclasts in the tibial metaphysis than those in wild type mice. These alterations in Igf1-null mice were only partially corrected by each PTHrP peptide treatment. The skeletal expression of Igf2, Igf1 receptor and Irs2 was increased in Igf1- null mice, and this compensatory profile was further improved by treatment with each PTHrP peptide related to ERK1/2 and FoxM1 activation. In vitro, PTHrP (1-36) and osteostatin were effective in promoting bone marrow stromal cell mineralization in normal mice but not in IGF-I-deficient mice. Collectively, these findings indicate that PTHrP (1- 36) and osteostatin can exert several osteogenic actions even in the absence of IGF-I in the mouse bone.

Paternally expressed, imprinted insulin-like growth factor-2 in chorionic villi correlates significantly with birth weight

Demetriou, C., Abu-Amero, S., Thomas, A.C., (…), Stanier, P., Moore, G.E.
2014 PLoS ONE 9 (1), e85454

Context: Fetal growth involves highly complex molecular pathways. IGF2 is a key paternally expressed growth hormone that is critical for in utero growth in mice. Its role in human fetal growth has remained ambiguous, as it has only been studied in term tissues. Conversely the maternally expressed growth suppressor, PHLDA2, has a significant negative correlation between its term placental expression and birth weight.
Objective: The aim of this study is to address the role in early gestation of expression of IGF1, IGF2, their receptors IGF1R and IGF2R, and PHLDA2 on term birth weight.
Design: Real-time quantitative PCR was used to investigate mRNA expression of IGF1, IGF2, IGF1R, IGF2R and PHLDA2 in chorionic villus samples (CVS) (n = 260) collected at 11-13 weeks’ gestation. Expression was correlated with term birth weight using statistical package R including correction for several confounding factors. Results: Transcript levels of IGF2 and IGF2R revealed a significant positive correlation with birth weight (0.009 and 0.04, respectively). No effect was observed for IGF1, IGF1R or PHLDA2 and birth weight. Critically, small for gestational age (SGA) neonates had significantly lower IGF2 levels than appropriate for gestational age neonates (p = 3·6610-7).
Interpretation: Our findings show that IGF2 mRNA levels at 12 weeks gestation could provide a useful predictor of future fetal growth to term, potentially predicting SGA babies. SGA babies are known to be at a higher risk for type 2 diabetes. This research reveals an imprinted, parentally driven rheostat for in utero growth

Jensen, R.B., Thankamony, A., O’Connell, S.M., (…), Dunger, D.B., Juul, A.
2014 European Journal of Endocrinology 171 (4), pp. 509-518

A randomised controlled trial evaluating IGF1 titration in contrast to current GH dosing strategies in children born small for gestational age: The North European Small-for-Gestational-Age Study

Minireview: Mechanisms of growth hormone- mediated gene regulation

Chia, D.J.
2014 Molecular Endocrinology 28 (7), pp. 1012-1025

GH exerts a diverse array of physiological actions that include prominent roles in growth and metabolism, with a major contribution via stimulating IGF-1 synthesis. GH achieves its effects by influencing gene expression profiles, and Igf1 is a key transcriptional target of GH signaling in liver and other tissues. This review examines the mechanisms of GH-mediated gene regulation that begin with signal transduction pathways activated downstream of the GH receptor and continue with chromatin events at target genes and additionally encompasses the topics of negative regulation and cross talk with other cellular inputs. The transcription factor, signal transducer and activator of transcription 5b, is regarded as the major signaling pathway by which GH achieves its physiological effects, including in stimulating Igf1 gene transcription in liver. Recent studies exploring the mechanisms of how activated signal transducer and activator of transcription 5b accomplishes this are highlighted, which begin to characterize epigenetic features at regulatory domains of the Igf1 locus. Further research in this field offers promise to better understand the GH-IGF-1 axis in normal physiology and disease and to identify strategies to manipulate the axis to improve human health.

Management of endocrine disease: GH excess: diagnosis and medical therapy.

Andersen, M.
2014 European journal of endocrinology / European Federation of Endocrine Societies 170 (1), pp. R31-41

Acromegaly is predominantly caused by a pituitary adenoma, which secretes an excess of GH resulting in increased IGF1 levels. Most of the GH assays used currently measure only the levels of the 22 kDa form of GH. In theory, the diagnostic sensitivity may be lower compared with the previous assays, which have used polyclonal antibodies. Many GH-secreting adenomas are plurihormonal and may co-secrete prolactin, TSH and ?-subunit. Hyperprolactinemia is found in 30-40% of patients with acromegaly, and hyperprolactinemia may occasionally be diagnosed before acromegaly is apparent. Although trans-sphenoidal surgery of a GH-secreting adenoma remains the first treatment at most centers, the role of somatostatin analogues, octreotide long-acting repeatable and lanreotide Autogel as primary therapy is still the subject of some debate. Although the normalization of GH and IGF1 levels is the main objective in all patients with acromegaly, GH and IGF1 levels may be discordant, especially during somatostatin analogue therapy. This discordance usually takes the form of high GH levels and an IGF1 level towards the upper limit of the normal range. Pasireotide, a new somatostatin analogue, may be more efficacious in some patients, but the drug has not yet been registered for acromegaly. Papers published on pasireotide have reported an increased risk of diabetes mellitus due to a reduction in insulin levels. Pegvisomant, the GH receptor antagonist, is indicated – alone or in combination with a somatostatin analogue – in most patients who fail to enter remission on a somatostatin analogue. Dopamine-D2-agonists may be effective as monotherapy in a few patients, but it may prove necessary to apply combination therapy involving a somatostatin analogue and/or pegvisomant.

Characterization and prevalence of severe primary IGF1 deficiency in a large cohort of French children with short stature

Teissier, R., Flechtner, I., Colmenares, A., (…), Souberbielle, J.C., Polak, M
2014 European Journal of Endocrinology 170 (6), pp. 847-854

Objective: The prevalence of severe primary IGF1 deficiency (IGFD) is unclear. IGFD must be identified promptly as treatment with recombinant human IGF1 (rhIGF1) is now available. Our objective was to characterize and assess the prevalence of severe primary IGFD in a large cohort of patients evaluated for short stature at a pediatric endocrinology unit in France.
Design: Observational study in a prospective cohort.
Methods: Consecutive patients referred to our unit between 2004 and 2009 for suspected slow statural growth were included. Patients were classified into eight etiological categories. IGFD was defined by height ? -3 SDS, serum IGF1 levels <2.5th percentile, GH sufficiency, and absence of causes of secondary IGFD.
Results: Out of 2546 patients included, 337 (13.5%) were born small for gestational age and 424 (16.9%) had idiopathic short stature. In these two categories, we identified 30 patients who met our criterion for IGFD (30/2546, 1.2%). In these 30 patients, we assessed the response to IGF1 generation test, time course of IGF1 levels, and efficiency of GH replacement therapy. The results indicated that only four of the 30 children were definite or possible candidates for rhIGF1 replacement therapy.
Conclusion: The prevalence of severe primary IGFD defined using the standard criterion for rhIGF1 treatment was 1.2%, and only 0.2% of patients were eligible for rhIGF1 therapy.

GH signaling in skeletal muscle and adipose tissue in healthy human subjects: Impact of gender and age

Vestergaard, P.F., Vendelbo, M.H., Pedersen, S.B., (…), Jessen, N., Jorgensen, J.O.L.
2014 European Journal of Endocrinology 171 (5), pp. 623-631

Objective: The mechanisms underlying the impact of age and gender on the GH-IGF1 axis remain unclear. We tested the hypothesis that age and gender have impacts on GH signaling in human subjects in vivo.
Design: A total of 20 healthy non-obese adults (‘young group’ <30 years (5F/5M) and ‘old group’ >60 years (5F/5M)) were studied after: i) an i.v. GH bolus (0.5 mg) and ii) saline.
Methods: Muscle and fat biopsies were obtained after 30 and 120 min. Total and phosphorylated STAT5B proteins, gene expression of IGF1, SOCS1, SOCS2, SOCS3 and CISH, body composition, VO2max, and muscle strength were measured. Results: In the GH-unstimulated state, women displayed significantly elevated levels of CISH mRNA in muscle (P=0.002) and fat (P=0.05) and reduced levels of IGF1 mRNA in fat. Phosphorylated STAT5B (pSTAT5b) was maximally increased in all subjects 30 min after GH exposure and more pronounced in women when compared with men (P=0.01). IGF1, SOCS1, SOCS2, SOCS3, and CISH mRNA expression increased significantly in muscle after 120 min in all subjects with no impact of age and gender. GH-induced pSTAT5b correlated inversely with lean body mass (LBM; r=-0.56, P Z0.01) and positively with the CISH mRNA response (r=0.533, P=0.05).
Conclusion: i) GH signaling in muscle and fat after a single GH bolus in healthy human subjects is age independent, ii) we hypothesize that constitutive overexpression of CISH may contribute to the relative GH resistance in women, and iii) experimental studies on the impact of sex steroid administration and physical training on GH signaling in human subjects in vivo are required.

Direct stimulation of bone mass by increased GH signaling in the osteoblasts of Socs2-/- mice

Dobie, R., MacRae, V.E., Huesa, C., (…), Ahmed, S.F., Farquharson, C.
2014 Journal of Endocrinology 223 (1), pp. 93-106

The suppressor of cytokine signaling (Socs2-/-)-knockout mouse is characterized by an overgrowth phenotype due to enhanced GH signaling. The objective of this study was to define the Socs2-/- bone phenotype and determine whether GH promotes bone mass via IGF1-dependent mechanisms. Despite no elevation in systemic IGF1 levels, increased body weight in 4-week-old Socs2-/- mice following GH treatment was associated with increased cortical bone area (Ct.Ar) (P<0.01). Furthermore, detailed bone analysis of male and female juvenile and adult Socs2-/- mice revealed an altered cortical and trabecular phenotype consistent with the known anabolic effects of GH. Indeed, male Socs2-/- mice had increased Ct.Ar (P<0.05) and thickness associated with increased strength. Despite this, there was no elevation in hepatic Igf1 expression, suggesting that the anabolic bone phenotype was the result of increased local GH action. Mechanistic studies showed that in osteoblasts and bone of Socs2-/- mice, STAT5 phosphorylation was significantly increased in response to GH. Conversely, overexpression of SOCS2 decreased GH-induced STAT5 signaling. Although an increase in Igf1 expression was observed in Socs2-/- osteoblasts following GH, it was not evident in vivo. Igf1 expression levels were not elevated in response to GH in 4-week-old mice and no alterations in expression was observed in bone samples of 6-week-old Socs2-/- mice. These studies emphasize the critical role of SOCS2 in controlling the local GH anabolic bone effects. We provide compelling evidence implicating SOCS2 in the regulation of GH osteoblast signaling and ultimately bone accrual, which maybe via mechanisms that are independent of IGF1 production in vivo.

Therapy of acromegalic patients exacerbated by concomitant type 2 diabetes requires higher pegvisomant doses to normalise IGF1 levels

Droste, M., Domberg, J., Buchfelder, M., (…), Stalla, G., Strasburger, C.J.
2014 European Journal of Endocrinology 171 (1), pp. 59-68

Objective: Acromegaly is associated with an increased prevalence of glucose metabolism disorders. Clinically confirmed diabetes mellitus is observed in approximately one quarter of all patients with acromegaly and is known to have a worse prognosis in these patients.
Design: Of 514 acromegalic patients treated with pegvisomant and recorded in the German Cohort of ACROSTUDY, 147 had concomitant diabetes mellitus. We analysed these patients in an observational study and compared patients with and without concomitant diabetes.
Results: Under treatment with pegvisomant, patients with diabetes mellitus rarely achieved normalization (64% in the diabetic cohort vs 75% in the non-diabetic cohort, P=0.04) for IGF1. Diabetic patients normalised for IGF1 required higher pegvisomant doses (18.9 vs 15.5 mg pegvisomant/day, P<0.01). Furthermore, those diabetic patients requiring insulin therapy showed a tendency towards requiring even higher pegvisomant doses to normalize IGF1 values than diabetic patients receiving only oral treatment (22.8 vs 17.2 mg pegvisomant/day, PZ0.11).
Conclusions: Hence, notable interdependences between the acromegaly, the glucose metabolism of predisposed patients and their treatment with pegvisomant were observed. Our data support recent findings suggesting that intra-portal insulin levels determine the GH receptor expression in the liver underlined by the fact that patients with concomitant diabetes mellitus, in particular those receiving insulin therapy, require higher pegvisomant doses to normalize IGF1. It is therefore important to analyse various therapy modalities to find out whether they influence the associated diabetes mellitus and/or whether the presence of diabetes mellitus influences the treatment results of an acromegaly therapy.

Sustained biochemical control in patients with acromegaly treated with lanreotide depot 120 mg administered every 4 weeks, or an extended dosing interval of 6 or 8 weeks: a pharmacokinetic approach

Edda Gomez-Panzani, S Chang, J Ramis, MM Landolfi, B Bakker
Research and Reports in Endocrine Disorders 2012:2 79–84
http://dx.doi.org/10.2147/RRED.S38149

Objective: Lanreotide depot is a long-acting somatostatin receptor ligand injected deep subcutaneously every 4 weeks for the treatment of acromegaly. The aim of the presented studies was to establish whether lanreotide depot, administered to patients with acromegaly at an extended dosing interval of 6 or 8 weeks, is effective in maintaining appropriate serum growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels, with acceptable tolerability.
Methods: Two studies were conducted. Study B1 compared lanreotide depot 120 mg (every 4, 6, or 8 weeks) with lanreotide microparticle formulation 30 mg (every 7, 10, or 14 days) in 98 patients who had a GH level of #2.5 ng/mL and normalized IGF-1. Study B2 evaluated lanreotide depot 120 mg administered to 64 patients every 8 weeks, after which the dosing interval was adjusted based on GH levels.
Results: Mean lanreotide trough serum concentrations at steady state for all dosing intervals were .1.13 ng/mL, shown to achieve a GH level of #2.5 ng/mL. In Study B1, following treatment with lanreotide depot given every 6 or 8 weeks, 87.5% and 93.9% of patients, respectively, had normalized GH, whereas 83.3% and 88.5% of patients, respectively, had both normalized GH and IGF-1. In Study B2, 88.9% had normalized GH and 42.9% of patients had normalized GH and IGF-1 following lanreotide depot every 8 weeks. Gastrointestinal disorders, generally mild/moderate in severity, were the most common adverse events.
Conclusion: In the studies presented, lanreotide depot 120 mg every 4, 6, or 8 weeks provided effective hormonal control with acceptable safety. An extended dosing interval is a feasible approach for patients adequately controlled with lanreotide depot 60 or 90 mg every 4 weeks.

The endocrine effects of acylated and des-acylated ghrelin

David E Andrich, K Cianflone, Alain-Steve Comtois, S Lalonde, DH St-Pierre
Research and Reports in Endocrine Disorders 2012:2 31–40
http://dx.doi.org/10.2147/RRED.S33480

Acylated ghrelin is one of the few peptides known whose isolation and characterization follow the description of its receptor and its basic biological functions. Characterized initially for its somatotrophic properties, ghrelin was shown later to exert various effects on other important physiological functions in mammals, such as appetite, gastric acid secretion, gut motility, insulin sensitivity, adiposity, and energy expenditure. Further, ghrelin influences cardiac function, reproduction, and the immune system as well. Here we present an overview of the discovery and subsequent development of ghrelin as an important peptide hormone involved in the control of energy metabolism in humans and other mammals. Recently reported effects of acylated ghrelin on glucose/lipid uptake, de novo lipogenesis, gluconeogenesis, lipid-droplet formation, fatty acid transport into mitochondria, and mitochondrial activity are particularly emphasized and discussed

Regulatory neuropeptides (ghrelin, obestatin and nesfatin-1) levels in serum and reproductive tissues of female and male rats with fructose-induced metabolic syndrome

Zekiye Catak, S Aydin, I Sahin, T Kuloglu, A Aksoy, AF Dagli
Neuropeptides 48 (2014) 167–177
http://dx.doi.org/10.1016/j.npep.2014.04.002

Although, the exact mechanisms underlying the development of the metabolic syndrome (MetS) are not still completely understood, obesity, circulated peptide hormone levels and their interaction with genetic factors are considered largely responsible. The purpose of this study is to explore how the levels of ghrelin, obestatin (OBS) and NUCB2/nesfatin-1 (NES)/NUCB2 change in serum and the reproductive tissues of female and male rats with fructose-induced metabolic syndrome, and whether the levels of each hormone is correlated with the hormones involved with fertility. Experiments were conducted on 5-week-old Sprague–Dawley male and female rats assigned to either a control group or a MetS group. Controls were fed standard rat food and water ad libitum, while the MetS group was fed standard food with 10% (v/v) fructose solution added to their drinking water for 12 weeks with a 12/12 h photoperiod circle. Then, all animals were sacrificed after a one night fast. Peptides levels in the serum and reproductive tissues of rats were studied using the ELISA method while the immunoreactivity of reproductive system peptide hormones were shown by immunohistochemical staining method. Furthermore, the other biochemical parameters were measured using Konelab-60 equipment and infertility hormones were measured with Immulite2000. Fasting serum insulin, glucose, triglyceride, alanine aminotransferase (ALT), gamma glutamyl transpeptidase (GGT), low-density lipoprotein cholesterol (LDL-C), and total cholesterol (TC) levels were statistically significantly higher, and the amount of high density lipoprotein cholesterol (HDL-C) was significantly lower, in the MetS groups. Serum and tissue supernatant NES levels were significantly higher in the rats with MetS than the control group. Ghrelin, OBS and NES were expressed in the cytoplasm, concentrated around the apical parts of the epithelial cells in the reproductive tissues of the rats. The amounts of ghrelin were lower in the reproductive tissues of the animals with MetS, while NES levels in the same tissues increased. Obestatin also decreased, though not in the seminal glands.

Hypothalamus Role in Stress Response and Adaptability

Oxytocin mechanisms of stress response and aggression in a territorial finch

James L. Goodson, Sara E. Schrock, Marcy A. Kingsbury
Physiology & Behavior 141 (2015) 154–163
http://dx.doi.org/10.1016/j.physbeh.2015.01.016

All jawed vertebrates produce a form of oxytocin (OT), and in birds, mammals and fish, OT is strongly associated with affiliation. However, remarkably few data are available on the roles of OT and OT receptors (OTRs) in aggression. Because OT and OTRs exert anxiolytic effects in mammals (although context-specific) and modulate stress coping, we hypothesized that OTR activation is at least permissive for territorial aggression. Indeed, we find that peripheral injections of an OTR antagonist significantly reduce male–male and female–female aggression in a highly territorial finch. This finding suggests the hypothesis that aggression is accompanied by an increase in transcriptional (Fos) activity of OT neurons, but contrary to this hypothesis, we find that dominant male residents do not elevate OT-Fos colocalization following an aggressive encounter and that OT-Fos colocalization in the preoptic area and hypothalamus correlates negatively with aggression. Furthermore, OT-Fos colocalization increases dramatically in males that were aggressively subjugated or pursued by a human hand, likely reflecting OT modulation of stress response. Because OT inhibits the hypothalamo–pituitary–adrenal axis, the antagonist effects may reflect the fact that aggressive birds and mammals tend to be hyporesponsive to stress. If this is correct, then 1) the observed effects of OTR antagonism may reflect alterations in corticosterone feedback to the brain rather than centrally mediated OTR effects, and 2) the negative correlation between OT-Fos colocalization and aggression may reflect the fact that more aggressive, stress hyporesponsive males require less inhibition of the hypothalamo–pituitary–adrenal axis than do less aggressive males, despite the requirement of that inhibition for the normal display of aggression.

Oxytocin induces social communication by activating arginine-vasopressin V1areceptors and not oxytocin receptors

Zhimin Song, Katharine E. McCann, John K. McNeill IV, et al.
Psychoneuroendocrinology (2014) 50, 14—19
http://dx.doi.org/10.1016/j.psyneuen.2014.08.005

Arginine-vasopressin (AVP) and oxytocin (OT) and their receptors are very similar in structure. As a result, at least some of the effects of these peptides may be     the result of crosstalk between their canonical receptors. The present study investigated this hypothesis by determining whether the induction of flank marking, a form of social communication in Syrian hamsters, by OT is mediated by the OT receptor or the AVP V1a receptor. Intracerebroventricular(ICV) injections of OT or AVP induced flank marking in a dose-dependent manner although the effects of AVP were approximately 100 times greater than those of OT. Injections of highly selective V1a receptor agonists but not OT receptor agonists induced flank marking, and V1a receptor antagonists but not OT receptor antagonists significantly inhibited the ability of OT to induce flank marking. Lastly, injection of alpha-melanocyte-stimulating hormone ([1]-MSH), a peptide that stimulates OT but not AVP release, significantly increased odor-induced flank marking, and these effects were blocked by a V1a receptor antagonist. These data demonstrate that OT induces flank marking by activating AVP V1a and not OT receptors, suggesting that theV1a receptor should be considered to be an OT receptor as well as an AVP receptor.

Levels of central oxytocin and glucocorticoid receptor and serum adrenocorticotropic hormone and corticosterone in mandarin voles with different levels of sociability

Xufeng Qiao, Yating Yan, Fadao Tai∗, Ruiyong Wu, Ping Hao, et al.
Behavioural Brain Research 274 (2014) 226–234
http://dx.doi.org/10.1016/j.bbr.2014.08.020

Sociability is the prerequisite to social living. Oxytocin and the hypothalamo-pituitary-adrenocortical axis mediate various social behaviors across different social contexts in different rodents. We hypothesized that they also mediate levels of non-reproductive social behavior. Here we explored naturally occurring variation in sociability through a social preference test and compared central oxytocin, glucocorticoid receptors, serum adrenocorticotropic hormone and corticosterone in mandarin voles with different levels of sociability.
We found that low-social voles showed higher levels of anxiety-like behavior in open field tests, and had more serum adrenocorticotropic hormone and corticosterone than high-social voles. High-social individuals had more glucocorticoid receptor positive neurons in the hippocampus and more oxytocin positive neurons in the paraventricular nuclei and supraoptic nuclei of the hypothalamus than low-social individuals.
Within the same level of sociability, females had more oxytocin positive neurons in the paraventricular nuclei and supraoptic nuclei of the hypothalamus than males. These results indicate that naturally occurring social preferences are associated with higher levels of central oxytocin and hippocampus glucocorticoid receptor and lower levels of anxiety and serum adrenocorticotropic hormone and corticosterone.

HPA axis genetic variation, pubertal status, and sex interact to predict amygdala and hippocampus responses to negative emotional faces in school-age children

David Pagliaccio, JL Luby, R Bogdan, A Agrawal, MS. Gaffrey, et al.
NeuroImage 109 (2015) 1–11
http://dx.doi.org/10.1016/j.neuroimage.2015.01.017

Accumulating evidence suggests a role for stress exposure, particularly during early life, and for variation in genes involved in stress response pathways in neural responsivity to emotional stimuli. Understanding how individual differences in these factors predict differences in emotional responsivity may be important for understanding both normative emotional development and for understanding the mechanisms underlying internalizing disorders, like anxiety and depression, that have often been related to increased amygdala and hippocampus responses to negatively valenced emotional stimuli. The present study examined whether stress exposure and genetic profile scores (10 single nucleotide polymorphisms within four hypothalamic–pituitary–adrenal axis genes: CRHR1, NR3C2, NR3C1, and FKBP5) predict individual differences in amygdala and hippocampus responses to fearful vs. neutral faces in school-age children (7–12 year olds; N = 107). Experience of more stressful and traumatic life events predicted greater left amygdala responses to negative emotional stimuli. Genetic profile scores interacted with sex and pubertal status to predict amygdala and hippocampus responses. Specifically, genetic profile scores were a stronger predictor of amygdala and hippocampus responses among pubertal vs. prepubertal children where they positively predicted responses to fearful faces among pubertal girls. and positively predicted responses to neutral faces among pubertal boys. The current results suggest that genetic and environmental stress-related factors may be important in normative individual differences in responsivity to negative emotional stimuli, a potential mechanism underlying internalizing disorders. Further, sex and pubertal development may be key moderators of the effects of stress-system genetic variation on amygdala and hippocampus responsivity, potentially relating to sex differences in stress-related psychopathology.

Hypothalamic—pituitary—adrenal axis activity in older persons with and without a depressive disorder

D. Rhebergen, N.C.M. Korten, B.W.J.H. Penninx, M.L. Stek, et al.
Psychoneuroendocrinology (2015) 51, 341—350
http://dx.doi.org/10.1016/j.psyneuen.2014.10.005

Background: Altered functioning of the hypothalamic—pituitary—adrenal axis (HPA-axis) has been associated with depression, but findings have been inconsistent. Among older depressed persons, both hyperactivity and hypo-activity of the HPA-axis were demonstrated. However, most studies were population-based studies, with single cortisol measurements, lacking insight into diurnal patterns of HPA-axis functioning. We aim to provide insight into functioning of the HPA-axis, assessed by various salivary cortisol samples, in depressed older adults and non-depressed controls.
Methods: Data were derived from the Netherlands Study of Depression in Older Persons. Cortisol levels of older persons without a lifetime diagnosis of depression and/or anxiety (n = 109) were compared with older persons with a 6-month major depression diagnosis (n = 311). ANCOVA analyses and random coefficient analysis on the four morning cortisol samples were performed. A possible U-shaped association between cortisol and depression status was examined.
Results: Depressed older persons showed higher morning cortisol levels at awakening (T1) and a less dynamic awakening response compared to non-depressed older persons. Dexamethasone suppression did not differ across groups. No U-shaped association between HPA-axis activity and depression was observed.
Conclusion: We demonstrated a hypercortisolemic state and a diminished ability to respond tothe stress of awakening among depressed older persons. Previously it was shown, that hyper-cortisolemic states may indicate a lifelong biological vulnerability for depression. Our findings expand on previous literature by demonstrating that in older persons the HPA-axis may become less responsive to stress, culminating in a further dysregulation of the diurnal cortisol-rhythm, superimposed on — possibly lifelong — hypercortisolemic states.

Hypothalamic–pituitary hormones during critical illness: a dynamic neuroendocrine response

Lies Langouche and Greet Van Den Berghe
Handbook of Clinical Neurology, Vol. 124 (3rd series)

Clinical Neuroendocrinology: Chapter 8

The early phase of illness is characterized by an actively secreting pituitary in the presence of low peripheral target hormones. The acute endocrine alterations can be considered beneficial, as they appear to delay costly anabolism and facilitate the release of substrates as fuel to vital tissues in order to improve survival. In the prolonged phase of critical illness, when recovery does not quickly ensue, a uniform hypothalamic–pituitary suppression occurs, further contributing to the low levels of peripheral target hormones. The ongoing hypercatabolism, despite the administration of artificial nutrition, leads to substantial loss of lean body mass. Ultimately, this may compromise recovery of vital functions and delay rehabilitation.

neuroendocrine changes during critical illness

neuroendocrine changes during critical illness

Simplified scheme of the neuroendocrine changes during the acute, chronic, and recovery phase of critical illness. In the acute phase of illness (first hours to a few days after onset), the secretory activity of the anterior pituitary is essentially maintained or amplified, whereas anabolic target organ hormones are inactivated. In the chronic phase of protracted critical illness (intensive care-dependent for weeks), the secretory activity of the anterior pituitary appears uniformly suppressed in relation to reduced circulating levels of target organ hormones. Impaired anterior pituitary hormone secretion allows the respective target organ hormones to decrease proportionately over time, with cortisol being a noteworthy exception, the circulating levels of which remain elevated. The onset of recovery is characterized by restored levels of target hormones and pituitary hormones. Shaded areas represent the range within which the hormonal changes occur.

GPER1 (GPR30) knockout mice display reduced anxiety and altered stress response in a sex and paradigm dependent manner

Iris Kastenberger, Christoph Schwarzer
Hormones and Behavior 66 (2014) 628–636
http://dx.doi.org/10.1016/j.yhbeh.2014.09.001

The putative estrogen receptor GPER1 (the former orphan receptor GPR30) is discussed to be involved in emotional and cognitive functions and stress control. We recently described the induction of anxiety-like effects by the GPER1 agonist G-1 upon systemic injection into mice. To contribute to a better understanding of the role of GPER1 in anxiety and stress, we investigated germ-line GPER1 deficient mice. Our experiments revealed marked differences between the sexes. A mild but consistent phenotype of increased exploratory drive was observed in the home cage, the elevated plus maze and the light–dark choice test in male GPER1 KO mice. In contrast, female GPER1-KO mice displayed a less pronounced phenotype in these tests. Estrous-stage dependent mild anxiolytic-like effects were observed solely in the open field test. Notably, we observed a strong shift in acute stress coping behavior in the tail suspension test and basal corticosterone levels in different phases of the estrous cycle in female GPER1-KO mice. Our data, in line with previous reports, suggest that GPER1 is involved in anxiety and stress control. Surprisingly, its effects appear to be stronger in male than female mice.

Testosterone and Estradiol Differentially Affect Cell Proliferation in the Subventricular Zone of Young Adult Gonadectomized Male and Female Rats

Farinetti, S. Tomasi, B. Foglio, A. Ferraris, G. Ponti,  S. Gotti, et al.
Neuroscience 286 (2015) 162–170
http://dx.doi.org/10.1016/j.neuroscience.2014.11.050

Steroid hormones are important players to regulate adult neurogenesis in the dentate gyrus of the hippocampus, but their involvement in the regulation of the same phenomenon in the subventricular zone (SVZ) of the lateral ventricles is not completely understood.
Here, in male rats, we tested the existence of activational effects of testosterone (T) on cell proliferation in the adult SVZ. To this aim, three groups of male rats: castrated, castrated and treated with T, and controls were treated with 5-bromo-20-deoxyuridine (BrdU) and killed after 24 h. The density of BrdU-labeled cells was significantly lower in castrated animals in comparison to the other two groups, thus supporting a direct correlation between SVZ proliferation and levels of circulating T.
To clarify whether this effect is purely androgen-dependent, or mediated by the T metabolites, estradiol (E2) and  dihydrotestosterone (DHT), we evaluated SVZ proliferation in castrated males treated with E2, DHT and E2+ DHT, in comparison to T- and vehicle-treated animals, and sham-operated controls. The stereological analysis demonstrated that E2 and T, but not DHT, increase proliferation in the SVZ of adult male rats. Quantitative evaluation of cells expressing the endogenous marker of cell proliferation phosphorylated form of Histone H3 (PHH3), or the marker of highly dividing SVZ progenitors Mash1, indicated the effect of T/E2 is mostly restricted to SVZ proliferating progenitors. The same experimental protocol was repeated on ovariectomized female rats treated with E2 or T. In this case, no statistically significant difference was found among groups.
Overall, our results clearly show that the gonadal hormones T and E2 represent important mediators of cell proliferation in the adult SVZ. Moreover, we show that such an effect is restricted to males, supporting adult neurogenesis in rats is a process differentially modulated in the two sexes.

Neuroendocrine regulation of inflammation

Caroline J. Padro, Virginia M. Sanders
Seminars in Immunology 26 (2014) 357–368
http://dx.doi.org/10.1016/j.smim.2014.01.003

The interaction between the sympathetic nervous system and the immune system has been documented over the last several decades. In this review, the neuroanatomical, cellular, and molecular evidence for neuroimmune regulation in the maintenance of immune homeostasis will be discussed, as well as the potential impact of neuroimmune dysregulation in health and disease.

mAbs and pituitary dysfunction: clinical evidence and pathogenic hypotheses

F Torino, A Barnabei, RM Paragliola, P Marchetti, R Salvatori and SM Corsello
European Journal of Endocrinology (2013) 169 R153–R164
http://dx.doi.org:/10.1530/EJE-13-0434

mAbs are established targeted therapies for several diseases, including hematological and solid malignancies. These agents have shown a favorable toxicity profile, but, despite their high selectivity, new typical side-effects have emerged. In cancer patients, pituitary dysfunction may be mainly due to brain metastases or primary tumors and to related surgery and radiotherapy. Anticancer agents may induce hypopituitarism in patients cured for childhood cancers. These agents infrequently affect pituitary function in adult cancer patients. Notably, hypophysitis, a previously very rare disease, has emerged as a distinctive side-effect of ipilimumab and tremelimumab, two mAbs inhibiting the cytotoxic T-lymphocyte antigen-4 receptor, being occasionally seen with nivolumab, another immune checkpoint inhibitor. Enhanced antitumor immunity is the suggested mechanism of action of these drugs and autoimmunity the presumptive mechanism of their toxicity. Recently, ipilimumab has been licensed for the treatment of patients affected by metastatic melanoma. With the expanding use of these drugs, hypophysitis will be progressively encountered by oncologists and endocrinologists in clinical practice. The optimal management of this potentially life-threatening adverse event needs a rapid and timely diagnostic and therapeutic intervention. Hypopituitarism caused by these agents is rarely reversible, requiring prolonged or lifelong substitutive hormonal treatment. Further studies are needed to clarify several clinical and pathogenic aspects of this new form of secondary pituitary dysfunction.

Aberrant gonadotropin-releasing hormone receptor (GnRHR) expression and its regulation of CYP11B2 expression and aldosterone production in adrenal aldosterone-producing adenoma (APA)

Yasuhiro Nakamura, NG. Hattangady, Ping Ye, F Satoh, Ryo Morimoto, et al.
Molecular and Cellular Endocrinology 384 (2014) 102–108
http://dx.doi.org/10.1016/j.mce.2014.01.016

Aberrant expression of gonadotropin-releasing hormone receptor (GnRHR) has been reported in human adrenal tissues including aldosterone-producing adenoma (APA). However, the details of its expression and functional role in adrenals are still not clear. In this study, quantitative RT-PCR analysis revealed the mean level of GnRHR mRNA was significantly higher in APAs than in human normal adrenal (NA) (P = 0.004). GnRHR protein expression was detected in human NA and neoplastic adrenal tissues. In H295R cells transfected with GnRHR, treatment with GnRH resulted in a concentration-dependent increase in CYP11B2 reporter activity. Chronic activation of GnRHR with GnRH  (100 nM), in a cell line with doxycycline-inducible GnRHR (H295R-TR/GnRHR), increased CYP11B2 expression and aldosterone production. These agonistic effects were inhibited by blockers for the calcium signaling pathway, KN93 and calmidazolium. These results suggest GnRH, through heterotopic expression of its receptor, may be a potential regulator of CYP11B2 expression levels in some cases of APA.

Additional sources:

Lies Langouche and Greet Van Den Berghe. Chapter 8. Hypothalamic–pituitary hormones during critical illness: a dynamic neuroendocrine response. In Handbook of Clinical Neurology, Vol. 124 (3rd series). Clinical Neuroendocrinology

Critical illness is the medical condition in which a patient, because of major surgery or severe illness, requires immediate intensive medical support of vital organ functions in order to survive. Independent of the underlying condition, critical illness is characterized by a uniform dysregulation of the hypothalamic–pituitary–peripheral axes. In the majority of these axes a clear biphasic pattern can be distinguished (Fig. 8.1). The early phase of illness is characterized by an actively secreting pituitary in the presence of low peripheral target hormones. The acute endocrine alterations can be considered beneficial, as they appear to delay costly anabolism and facilitate the release of substrates as fuel to vital tissues in order to improve survival. In the prolonged phase of critical illness, when recovery does not quickly ensue, a uniform hypothalamic–pituitary suppression occurs, further contributing to the low levels of peripheral target hormones. The ongoing hypercatabolism, despite the administration of artificial nutrition, leads to substantial loss of lean body mass. Ultimately, this may compromise recovery of vital functions and delay rehabilitation. The severity of the neuroendocrine alterations is associated with a high risk of morbidity and mortality in the intensive care unit (ICU).

  1. Fliers, A. Boelen, and A.S.P. Van Trotsenburg. Chapter 9. Central regulation of the hypothalamo–pituitary–thyroid (HPT) axis: focus on clinical aspects. In Handbook of Clinical Neurology, Vol. 124 (3rd series). Clinical Neuroendocrinology

The tripeptide thyrotropin-releasing hormone (TRH) was first isolated from the hypothalamus in the late 1960s, and its neuronal expression in various hypothalamic nuclei was demonstrated when immunocytochemistry became available for neuroanatomic studies in the 1970s. These studies helped establish the pivotal role for TRH neurons in the hypothalamic paraventricular nucleus (PVN) in the neuroendocrine regulation of the hypothalamo–pituitary–thyroid (HPT) axis. The demonstration of an inverse relationship between plasma thyroid hormone concentrations and TRH mRNA expression in the PVN during experimentally induced hyper- and hypothyroidism (Segerson et al., 1987) confirmed the central role of TRH neurons in the HPT axis as a classic neuroendocrine feedback loop. The neuroanatomic distribution of TRH neurons in the human hypothalamus was reported only in the 1990s.

Kelly Cheer and Peter J. Trainer. Chapter 10. Evaluation of pituitary function. In Handbook of Clinical Neurology, Vol. 124 (3rd series). Clinical Neuroendocrinology.

This chapter aims to give a rational, reliable and strategic approach to pituitary investigation with understanding of the underlying physiology, thereby increasing confidence when seeing patients with pituitary dysfunction or reading about dynamic pituitary function tests in clinical letters.

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Sex Hormones, Adrenal Cortisol, Prostaglandins

 

Curator: Larry H. Bernstein, MD, FCAP

Steroids

A major class of lipids, steroids, have a ring structure of three cyclohexanes and one
cyclopentane in a fused ring system as shown below. There are a variety of functional
groups that may be attached. The main feature, as in all lipids, is the large number of
carbon-hydrogens which make steroids non-polar.

Steroids include such well known compounds as cholesterol, sex hormones, birth
control pills, cortisone, and anabolic steroids.

cholesterol

cholesterol

http://www.elmhurst.edu/~chm/vchembook/images/556cholesterol.gif

 The best known and most abundant steroid in the body is cholesterol. Cholesterol is
formed in brain tissue, nerve tissue, and the blood stream. It is the major compound
found in gallstones and bile salts. Cholesterol also contributes to the formation of
deposits on the inner walls of blood vessels. This topic was covered in the previous
discussion of the lipids series, and extensively in cardiovascular topics.

Cholesterol is synthesized by the liver from carbohydrates and proteins as well as fat.
Therefore, the elimination of cholesterol rich foods from the diet does not necessarily
lower blood cholesterol levels. Some studies have found that if certain unsaturated fats
and oils are substituted for saturated fats, the blood cholesterol level decreases.
The research is incomplete on this problem.

Cholesterol exists as an ester with fatty acids.What is the functional group at carbon 3
which is used to make an ester?
OH is alcohol

What is the feature on carbon 17?
Branched long hydrocarbon chain

Sex Hormones

sex hormones

sex hormones

http://www.elmhurst.edu/~chm/vchembook/images/556sexhormones.gif

 The primary sex hormones, testosterone and estrogen, are responsible for the
development of secondary sex characteristics. Two female sex hormones,
progesterone and estrogen or estradiol control the ovulation cycle. Notice
that the male and female hormones have only slight differences in structures,
but yet have very different physiological effects.

Testosterone promotes the normal development of male genital organs and
is synthesized from cholesterol in the testes. It also promotes secondary male
sexual characteristics such as deep voice, facial and body hair.

Estrogen, along with progesterone regulates changes occurring in the uterus
and ovaries known as the menstrual cycle. Estrogen is synthesized from
testosterone by making the first ring aromatic which results in the loss of a
methyl group and formation of an alcohol group.

List three functional groups in progesterone?
C#3 & #17 are ketones; C#4&5 are alkenes;

What is difference between progesterone and testosterone?
testosterone has C#17 alcohol vs ketone on progesterone

What is difference between testosterone and estrogen?
Estrogen has C#3 alcohol, + aromatic first ring;
no methyl group on C#17

Adrenocorticoid Hormones

The adrenocorticoid hormones are products of the adrenal glands.

The most important mineralcorticoid is aldosterone, which regulates the
reabsorption of sodium and chloride ions in the kidney tubules and increases
the loss of potassium ions.Aldosterone is secreted when blood sodium ion
levels are too low to cause the kidney to retain sodium ions. If sodium
levels are elevated, aldosterone is not secreted, so that some sodium
will be lost in the urine. Aldosterone also controls swelling in the tissues.

Cortisol, the most important glucocortinoid, has the function of increasing
glucose and glycogen concentrations in the body. These reactions are
completed in the liver by taking fatty acids from lipid storage cells and
amino acids from body proteins to make glucose and glycogen.

In addition, cortisol is elevated in the circulation with cytokine mediated
(IL1, IL1, TNFα) inflammatory reaction, called the systemic inflammatory
response syndrome. Its ketone derivative, cortisone, has the ability
to relieve inflammatory effects. Cortisone or similar synthetic derivatives
such as prednisolone are used to treat inflammatory diseases, rheumatoid
arthritis, and bronchial asthma. There are many side effects with the use
of cortisone drugs, such as bone resorption, so there use must be
monitored carefully.  Cortisol is increased pathologically with the growth
of a pituitary gland tumor that secretes adrenocorticotropic hormone
(ACTH), called Addison’s Disease, which is also associated with
hirsuit features.

What is the only difference between cortisol and aldosterone?
Aldosterone has C#13 aldehyde instead of methyl group

cortisone

cortisone

http://www.elmhurst.edu/~chm/vchembook/images/556cortisone.gif

Prostaglandins

Prostaglandins, are like hormones in that they act as chemical messengers,
but do not move to other sites, but work right within the cells where
they are synthesized. (PARACRINE)

Prostaglandins are unsaturated carboxylic acids, consisting of of a 20 carbon
skeleton that also contains a five member ring. They are biochemically
synthesized from the fatty acid, arachidonic acid.

arachidonic acid

arachidonic acid

http://www.elmhurst.edu/~chm/vchembook/images/551arachidonic.gif

 The unique shape of the arachidonic acid caused by a series of cis double
bonds
 helps to put it into position to make the five member ring.

Prostaglandins are unsaturated carboxylic acids, consisting of a

  • 20 carbon skeleton that also contains
  • a five member ring and
  • are based upon the fatty acid, arachidonic acid.

There are a variety of structures one, two, or three double bonds. On the
five member ring there may also be double bonds, a ketone, or alcohol groups.

In PGE2, list all of the functional groups.
one acid; two alkenes; two alcohols; one ketone

What is difference the C=C double bonds?
the upper is cis; the lower is trans.

prostaglandin PGE2

prostaglandin PGE2

http://www.elmhurst.edu/~chm/vchembook/images/556prostaglandin.gif

Functions of Prostaglandins 

There are a variety of physiological effects including:

  1. Activation of the inflammatory response, production of pain, and fever.
    When tissues are damaged, white blood cells flood to the site to
    try to minimize tissue destruction. Prostaglandins are produced
    as a result.
  2. Blood clots form when a blood vessel is damaged. A type of
    prostaglandin called thromboxane stimulates constriction and
    clotting of platelets. Conversely, PGI2, is produced to have the
    opposite effect on the walls of blood vessels where clots
    should not be forming.
  3. Certain prostaglandins are involved with the induction of labor
    and other reproductive processes. PGE2 causes uterine
    contractions and has been used to induce labor.
  4. Prostaglandins are involved in several other organs such as
    the gastrointestinal tract (inhibit acid synthesis and increase
    secretion of protective mucus), increase blood flow in kidneys,
    and leukotriens promote constriction of bronchi associated
    with asthma.

When you see that prostaglandins induce inflammation, pain, and fever,
what comes to mind but aspirin. Aspirin blocks an enzyme called
cyclooxygenase, COX-1 and COX-2, which is involved with the ring
closure and addition of oxygen to arachidonic acid converting to
prostaglandins.

The acetyl group on aspirin is hydrolzed and then bonded to the
alcohol group of serine as an ester. This has the effect of blocking
the channel in the enzyme and arachidonic can not enter the active
site of the enzyme.

By inhibiting or blocking this enzyme, the synthesis of prostaglandins
is blocked, which in turn relives some of the effects of pain and fever.

cox1 aspirin

cox1 aspirin

http://www.elmhurst.edu/~chm/vchembook/images/556coxaspirin.gif

 http://www.elmhurst.edu/~chm/vchembook/

 Sphingolipids

Sphingolipids are a second type of lipid found in cell membranes, particularly
nerve cells and brain tissues. They do not contain glycerol, but retain the
two alcohols with the middle position occupied by an amine.

As shown in the graphic, sphingosine has three parts, a three carbon
chain with two alcohols and amine attached and a long hydrocarbon chain.

http://www.elmhurst.edu/~chm/vchembook/images/556sphingosine.gif

 Structure of Sphingomyelin

In sphingomyelin, the base sphingosine has several other groups attached
as shown in the graphic on the left. A fatty acid is attached to the amine
through amide bond. Phosphate is attached through a phosphate ester bond,
and again through a phosphate ester bond to choline.

The human brain and spinal cord is made up of gray and white regions.
The white region is made of nerve axons wrapped in a white lipid coating,
the myelin sheath, which provides insulation to allow rapid conduction of
electrical signals. Multiple sclerosis caused by a gradual degradation of
the myelin sheath.

Sphingomyleins are located throughout the body in nerve cell membranes.
They make up about 25 % of the lipids in the myelin sheath that surrounds
and insulates cells of the central nervous system.

Niemann-Pick disease is caused by a deficiency of an enzyme that breaks
down excessive sphingomyelin, which then builds up on the liver, spleen,
brain, and bone marrow. An effected child usually dies within several years.

sphingomyelin

sphingomyelin

http://www.elmhurst.edu/~chm/vchembook/images/556sphingomyelin.gif

Glycolipids and Cerebrosides

Glycolipids are complex lipids that contain carbohydrates. Cerebrosides are an
example which contain the sphingosine backbone attached to a fatty acid and
a carbohydrate. The carbohydrates are most often glucose or galactose. Those
that contain several carbohydrates are called gangliosides. The example on the
left is shown with glucose. Glucocerebroside has the specific function to be in
the cell membranes of macrophages, (cells that protect the body by destroying
foreign microorganisms. Galactocerebroside is found almost exclusively in the
membranes of brain cells.

There are several genetic diseases resulting from the absence of specific enzymes
which breakdown the glycolipids. Tay-Sachs, which mainly effects Jewish children,
results in a build up of gangliosides and result in death in several years. Gaucher’s
disease results in the excessive build up of glucocerebroside resulting in severe
anemia and enlarged liver and spleen.

cerebroside

cerebroside

http://www.elmhurst.edu/~chm/vchembook/images/556cerebroside.gif

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Calcium Dependent NOS Induction by Sex Hormones: Estrogen

Reporter and Curator:  Sudipta Saha, Ph.D.

Nitric oxide (NO) synthases (NOSs) constitute a family of isozymes that catalyze the oxidation of L-arginine to NO and citrulline. First identified in the vascular endothelium, NO synthesis has subsequently been shown to play important roles in:

  • the regulation of vascular and gastrointestinal tone,
  • in cell-mediated cytotoxicity against bacteria and tumors, and
  • in a variety of central and peripheral nervous system activities.

NOSs can be divided into three functional classes based on their sensitivity to calcium.

  • The cytokine- or bacterial product-inducible isoenzyme iNOS binds calmodulin tightly at resting intracellular calcium concentrations.
  • The constitutive forms, isozymes eNOS (originally described in endothelial cells) and
  • nNOS (originally described in neuronal tissue), bind calmodulin in a reversible and calcium-dependent fashion.

The mechanisms by which their synthesis is controlled are unknown. The cDNA species encoding the rat, mouse, and human nNOS, the human and bovine eNOS, and iNOS from several species and cell types have been cloned and sequenced. The three human isozymes characterized to date are distinct, with their deduced protein sequences showing only 50-60%o amino acid identity. nNOS, which in rats and humans localizes to neurons in the central and peripheral nervous system and colocalizes with NADPHdiaphorase activity, has also been shown to be widely distributed in several non-neuronal tissues including human skeletal muscle.

It had been thought that both nNOS and eNOS were purely constitutive enzymes, although studies suggest eNOS may be induced by shear stress. Studies demonstrate that these NOSs can be induced in several tissues during pregnancy and in nonpregnant female and male animals by estradiol and that in skeletal muscle it is accompanied by an increase in NOS-specific mRNA.

Evidences emerging from various laboratories showed that there is an increase in the release of NO from the vasculature during pregnancy. Furthermore, treatment of pregnant animals at the end of gestation with tamoxifen reduced NOS activity in the cerebellum, an organ where tamoxifen acts as a pure estrogen-receptor antagonist. Thus, the increase in calcium-dependent NOS activity during pregnancy is mediated by estrogen. This conclusion is supported by the fact that treatment of nonpregnant females and male animals with estradiol also increased calcium-dependent NOS activity in all tissues studied.

Interestingly, testosterone treatment also increased cerebellar NOS activity without affecting other tissues. However, testosterone may increase brain NOS by directly binding estrogen receptors as has been reported. Furthermore, the cerebellum was the only tissue in the male to respond to a 5-day course of estradiol, suggesting that it may have a larger number and/or a greater availability of estrogen receptors than other tissues. In addition, the brain is rich in aromatase, which converts testosterone into estradiol. This, together with the observation that progesterone does not induce NOS, indicates that the induction of both nNOS and eNOS is specific for estrogen and not a characteristic of all sex steroids. These experiments do not exclude the possibility that the addition of progesterone might modify the estradiol effect.

The increases in NOS activity are the result of augmented enzyme synthesis (enzyme induction) since they are accompanied by increases in the specific mRNAs for both eNOS and nNOS. It is not, however, possible to tell whether the increases in mRNA are caused by an upregulation of mRNA synthesis (transcriptional induction) or decreased mRNA breakdown.

Although calcium-dependent NOS activity was increased by estradiol in tissues obtained from both female and male guinea pigs, a longer duration of treatment was necessary in the male. The most likely explanation for this observation is that the number or availability of estrogen receptors is initially too low in most tissues of the male and requires a period of estrogen priming. Although other factors may play a role, the duration of exposure may well explain the observation that the effect of pregnancy on NOS-specific mRNA is greater than estradiol alone.

The observation that estradiol induces calcium-dependent NOSs has several important implications:

  • An increase in release of NO from the endothelium would decrease vascular tone and contractility, events that are characteristic in pregnancy.
  • Heterogeneity among tissue endothelium regarding the effects of estrogen on basal NO release could explain the selective redistribution of maternal cardiac output to organs important for a successful pregnancy.
  • Consistent with this possibility is the observation that the effect of pregnancy on endothelium-derived NO is greatest in the uterine artery, followed by the mesenteric artery and then renal arteries.
  • An alternative hypothesis to explain the adaptation of smooth muscle to pregnancy is that it is caused by prostacyclin. Prostacyclin is increased during pregnancy and contributes to the observed reduced contractility of the ovine uterine artery to angiotensin II.

However, estradiol does not increase the synthesis of prostacyclin by the endothelium, nor does inhibition of prostacyclin synthesis prevent the effects of pregnancy on smooth muscle. In addition, both the incidence of esophageal reflux and the gastrointestinal transit time are increased during pregnancy. Although this phenomenon has previously been attributed to a direct effect of progesterone, NO is a powerful dilator of the gastrointestinal smooth muscle. If the increase in NOS activity observed in the esophagus applies to the bowel, enhanced NO might be the mechanism underlying both increased esophageal reflux and transit time.

The biological signifcance of an estradiol-dependent increase in the NOS in the central nervous system is of great interest and deserves further investigation. Furthermore, an estradiol-mediated increase in NOS in the vasculature could be the mechanism whereby premenopausal women are protected from coronary artery disease since increased NOS may slow the development of atherosclerosis and reduce the contractile response to acute thrombosis. Finally, the induction of calcium-dependent NOS enzymes by estradiol suggests that the present classification of this family of enzymes into constitutive and inducible types needs to be revised, since eNOS and nNOS enzymes at least are both constitutive and inducible.

Source References:

http://www.ncbi.nlm.nih.gov/pubmed?term=Calcium%20dependent%20NOS%20induction%20by%20sex%20hormones

Other research published on Nitric Oxide on this Scientific Web Site include the following:

Nitric Oxide in bone metabolism July 16, 2012

Author: Aviral Vatsa PhD, MBBS

https://pharmaceuticalintelligence.com/2012/07/16/nitric-oxide-in-bone-metabolism/?goback=%2Egde_4346921_member_134751669

 

Nitric Oxide production in Systemic sclerosis July 25, 2012

Curator: Aviral Vatsa, PhD, MBBS

https://pharmaceuticalintelligence.com/2012/07/25/nitric-oxide-production-in-systemic-sclerosis/?goback=%2Egde_4346921_member_138370383

Nitric Oxide Signalling Pathways August 22, 2012 by

Curator/ Author: Aviral Vatsa, PhD, MBBS

https://pharmaceuticalintelligence.com/2012/08/22/nitric-oxide-signalling-pathways/?goback=%2Egde_4346921_member_151245569

Nitric Oxide: a short historic perspective August 5, 2012

Author/Curator: Aviral Vatsa PhD, MBBS

https://pharmaceuticalintelligence.com/2012/08/05/nitric-oxide-a-short-historic-perspective-7/

 

Nitric Oxide: Chemistry and function August 10, 2012

Curator/Author: Aviral Vatsa PhD, MBBS

https://pharmaceuticalintelligence.com/2012/08/10/nitric-oxide-chemistry-and-function/?goback=%2Egde_4346921_member_145137865

Nitric Oxide and Platelet Aggregation August 16, 2012 by

Author: Dr. Venkat S. Karra, Ph.D.

https://pharmaceuticalintelligence.com/2012/08/16/no-and-platelet-aggregation/?goback=%2Egde_4346921_member_147475405

 

The rationale and use of inhaled NO in Pulmonary Artery Hypertension and Right Sided Heart Failure August 20, 2012

Author: Larry Bernstein, MD

https://pharmaceuticalintelligence.com/2012/08/20/the-rationale-and-use-of-inhaled-no-in-pulmonary-artery-hypertension-and-right-sided-heart-failure/

Nitric Oxide: The Nobel Prize in Physiology or Medicine 1998 Robert F. Furchgott, Louis J. Ignarro, Ferid Murad August 16, 2012

Reporter: Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2012/08/16/nitric-oxide-the-nobel-prize-in-physiology-or-medicine-1998-robert-f-furchgott-louis-j-ignarro-ferid-murad/

 

Coronary Artery Disease – Medical Devices Solutions: From First-In-Man Stent Implantation, via Medical Ethical Dilemmas to Drug Eluting Stents August 13, 2012

Author: Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2012/08/13/coronary-artery-disease-medical-devices-solutions-from-first-in-man-stent-implantation-via-medical-ethical-dilemmas-to-drug-eluting-stents/

Cardiovascular Disease (CVD) and the Role of agent alternatives in endothelial Nitric Oxide Synthase (eNOS) Activation and Nitric Oxide Production July 19, 2012

Curator and Research Study Originator: Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2012/07/19/cardiovascular-disease-cvd-and-the-role-of-agent-alternatives-in-endothelial-nitric-oxide-synthase-enos-activation-and-nitric-oxide-production/

Macrovascular Disease – Therapeutic Potential of cEPCs: Reduction Methods for CV Risk

An Investigation of the Potential of circulating Endothelial Progenitor Cells (cEPCs) as a Therapeutic Target for Pharmacological Therapy Design for Cardiovascular Risk Reduction: A New Multimarker Biomarker Discovery

Curator: Aviva Lev-Ari, PhD, RN, July 12, 2012

https://pharmaceuticalintelligence.com/2012/07/02/macrovascular-disease-therapeutic-potential-of-cepcs-reduction-methods-for-cv-risk/

 

Bone remodelling in a nutshell June 22, 2012

Author: Aviral Vatsa, Ph.D., MBBS

https://pharmaceuticalintelligence.com/2012/06/22/bone-remodelling-in-a-nutshell/

Targeted delivery of therapeutics to bone and connective tissues: current status and challenges – Part 1

AuthorL Aviral Vatsa, PhD, September 23, 2012

https://pharmaceuticalintelligence.com/2012/09/23/targeted-delivery-of-therapeutics-to-bone-and-connective-tissues-current-status-and-challenges-part-i/

Calcium dependent NOS induction by sex hormones: Estrogen

Curator: S. Saha, PhD, October 3, 2012

https://pharmaceuticalintelligence.com/2012/10/03/calcium-dependent-nos-induction-by-sex-hormones/

 

Nitric Oxide and Platelet Aggregation

Author V. Karra, PhD, August 16, 2012

https://pharmaceuticalintelligence.com/2012/08/16/no-and-platelet-aggregation/

Bystolic’s generic Nebivolol – positive effect on circulating Endothelial Progenitor Cells endogenous augmentation

Curator: Aviva Lev-Ari, PhD, July 16, 2012

https://pharmaceuticalintelligence.com/?s=Nebivolol

 

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