Feeds:
Posts
Comments

Posts Tagged ‘Thiol’


Alteration in Reduced Glutathione level in Red Blood Cells: Role of Melatonin

Author: Shilpa Chakrabarti, PhD

List of abbreviation:
DTNB- 5,5- dithiobis,2-nitrobenzoic acid
t-BHP- Tertiary butyl hydroperoxide
GSH-Reduced glutathione
GSSG- Oxidised glutathione

Objective: The study was taken up to see the effect of melatonin on the alteration of reduced glutathione level in red blood cells.

Pineal melatonin is involved in many physiological functions, the most important among them being sleep promotion and circadian regulation. This pineal product exhibits characteristic diurnal rhythm of synthesis and secretion, which attains its peak at night followed by a gradual decrease during the daytime. Melatonin detoxifies highly toxic hydroxyl and peroxyl radicals in vitro, scavenges hydrochlorous acid, as well as peroxynitrite. It has also been reported to increase the synthesis of glutathione and of several antioxidant enzymes [1].

Method: The present study was undertaken to understand the modulation of intracellular reduced glutathione (GSH) by melatonin in human red blood cells according to the oscillatory circadian changes in levels of this hormone.We have also studied the dose-dependent effect of melatonin on GSH in erythrocytes obtained from blood at two different times, subjected to oxidative stress by incubating with tert-butyl hydroperoxide (t-BHP) [2]. We used t-BHP as pro-oxidant [3]. Erythrocyte GSH was measured following the method of Beutler [4]. The method was based on the ability of the –SH group to reduce 5,5- dithiobis,2-nitrobenzoic acid (DTNB) and form a yellow coloured anionic product whose OD is measured at 412 nm.

A suspension of packed red blood cells in phosphate-buffered saline (PBS) containing glucose was treated with melatonin taken at different concentrations. A stock solution (10mM) of melatonin was prepared in absolute ethanol; further dilutions (100 uM–10 nM) were done with PBS. The concentration of ethanol was alwaysThe in vitro effect of melatonin was evaluated by incubating erythrocytes with melatonin at different doses (10 uM –1 nM final concentration) of melatonin for 30 minutes at 37°C. After washing the erythrocytes with the buffer, to remove any amount of the compound, and finally, packed erythrocytes were used for the assay of GSH. In parallel control experiments, blood was incubated with ethanol (final concentration not more than 0.01% (v/v)) but without melatonin.Oxidative stress was induced in vitro by using tert-butyl hydroperoxide both in presence and absence of melatonin. Use of TBHP is in accordance with the published reports [5].

Results and Discussion: The experiment demonstrated that erythrocyte GSH level increased in nocturnal samples which highlights the role of endogenous melatonin in the circadian changes in cellular glutathione level. Exogenous melatonin demonstrated a protective effect against t-BHP-induced peroxidative damage in both diurnal and nocturnal samples, the effect being more pronounced in aliquots containing very low concentration of melatonin (10 nM – 1 nM) [6]. Melatonin was found to inhibit GSH oxidation in a dose-dependent manner.

Melatonin has been found to upregulate cellular glutathione level to check lipid peroxidation in brain cells [7]. We may say that the incubation of the red cells with melatonin for an extended period (more than 30 minutes) may not have the same effects on the level of glutathione in these cells [12]. Melatonin may act as pro-oxidant in the cells exposed to the indoleamine for longer time. Also, the half-life period of pineal melatonin is for 30 to 60 minutes, as reviewed by Karasek and Winczyk [11].The recycling of glutathione in the cells depends on an NADPH-dependent glutathione enzyme system which includes glutathione peroxidise, glutathione reductase, and γ-glutamyl-cysteine synthase forming a meshwork of an antioxidative system. The stimulatory effect of melatonin on the regulation of the antioxidant enzymes has been reported [8].Since melatonin has an amphiphilic nature, its antioxidative efficiency crosses the cellular membrane barriers in a non-receptor-mediated mechanism. Another explanation of melatonin’s antioxidative activity may be based on its role in the upregulation of some antioxidant enzymes directly. Blanco et al had reported that glutathione reductase and glutathione peroxidase, the major constituents of the glutathione-redox system being stimulated by melatonin [9]. The plasma GSH/GSSG redox state is controlled by multiple processes, which includes synthesis of GSH from its constitutive amino acids, cyclic oxidation and reduction involving GSH peroxidase and GSSG reductase, transport of GSH into the plasma, and the degradation of GSH and GSSG by γ-glutamyltranspeptidase. The increase in erythrocyte GSH concentration after melatonin administration can be related Blanco et al’s report on the known stimulation of γ-glutamylcysteine synthase,a rate-limiting enzyme in reduced glutathione synthesis, by melatonin [10].

Conclusion: On the basis of our study, we may conclude that melatonin affects the glutathione level in red blood cells in a circadian manner. The rhythmic pattern of glutathione level confirms the relationship between physiological melatonin and erythrocyte GSH level and pharmacological dosage of the drug. The role of melatonin as an antioxidant and its activity in relation to these biomarkers has been studied in the above experiments.

Key words: Glutathione, circadian rhythm,, melatonin, biomarkers, oxidative stress

REFERENCES


1. D. Bonnefont-Rousselot and F. Collin, “Melatonin: action as antioxidant and potential applications in human disease and aging,” Toxicology, vol. 278, no. 1, pp. 55–67, 2010. http://www.drvitaminsolutions.com/images/products/Melatonin%20as%20antioxidant%20and%20potential%20applications%20in%20human%20disease%20and%20aging.pdf
2. A. V.Domanski, E. A. Lapshina, and I. B. Zavodnik, “Oxidative processes induced by tert-butyl hydroperoxide in human red blood cells: chemiluminescence studies,” Biochemistry (Moscow), vol. 70, no. 7, pp. 761–769, 2005. http://link.springer.com/article/10.1007%2Fs10541-005-0181-5
3. Z. Cˇervinkova´, P. Krˇiva´kova´, A. La´bajova´ et al., “Mechanisms participating in oxidative damage of isolated rat hepatocytes,” Archives of Toxicology, vol. 83, no. 4, pp. 363–372, 2009. http://www.ncbi.nlm.nih.gov/pubmed/16097939
4. E. Beutler, A Manual of Biochemical Methods, Grunne and Stratton, New York, NY, USA, 1984.
5. P. Di Simplicio, M. G. Cacace, L. Lusini, F. Giannerini, D. Giustarini, and R. Rossi, “Role of protein -SH groups in redox homeostasis—the erythrocyte as a model system,” Archives of Biochemistry and Biophysics, vol. 355, no. 2, pp. 145–152, 1998.
6. S. Chakravarty and S. I. Rizvi., “Day and Night GSH andMDA Levels in Healthy Adults and Effects of Different Doses ofMelatonin on These Parameters” International Journal of Cell Biology, vol. 2011, pp. Article ID 404591.http://www.hindawi.com/journals/ijcb/2011/404591/9CDay+and+Night+GSH+andMDA+Levels+in+Healthy+Adults+and+Effects+of+Different+Doses+ofMelatonin+on+These+Parameters”>
7. S. R. Pandi-Perumal, V. Srinivasan, G. J. M. Maestroni, D. P. Cardinali, B. Poeggeler, and R. Hardeland, “Melatonin: nature’s most versatile biological signal?” FEBS Journal, vol. 273, no. 13, pp. 2813–2838, 2006.http://onlinelibrary.wiley.com/doi/10.1111/j.1742-4658.2006.05322.x/full
8. R. J. Reiter, R. C. Carneiro, and C. S. Oh, “Melatonin in relation to cellular antioxidative defense mechanisms,” Hormone and Metabolic Research, vol. 29, no. 8, pp. 363–372, 1997.http://www.ncbi.nlm.nih.gov/pubmed/9288572
9. Y.Urata, S.Honma, S. Goto et al., “Melatonin induces gammaglutamylcysteine synthetase mediated by activator protein-1in human vascular endothelial cells,” Free Radical Biology and Medicine, vol. 27, no. 1-2, pp. 838–847, 1997.http://www.ncbi.nlm.nih.gov/pubmed/10515588
10. R. A. Blanco, T. R. Ziegler, B. A. Carlson et al., “Diurnal variation in glutathione and cysteine redox states in human plasma,” American Journal of Clinical Nutrition, vol. 86, no. 4, pp. 1016–1023, 2007. http://www.ncbi.nlm.nih.gov/pubmed/17921379
11. M. Karasek, K. Winczyk, “Melatonin in humans,” Journal of Phsiology and Pharmacology, vol. 57, no. 5, pp. 19-39, 2006. http://www.jpp.krakow.pl/journal/archive/11_06_s5/articles/02_article.html
12. A. Krokosz ,J. Grebowski, Z. Szweda-Lewandowska et al., ” Can melatonin delay oxidative damage of human
erythrocytes during prolonged incubation?” Advances in Medical Sciences, vol. 58, no. 1, 2013.http://www.researchgate.net/publication/236614971_Can_melatonin_delay_oxidative_damage_of_human_erythrocytes_during_prolonged_incubation

 

Read Full Post »