FREE RADICAL LOAD IN LYMPHOID ORGANS (SPLEEN AND THYMUS) OF INDIAN GOAT CAPRA HIRCUS: ROLE OF SEX, SEASON AND MELATONIN

Objective: Lymphoid organs (i.e. spleen and thymus) are important due to functional dynamicity. As a result, the generated free radicals may limit their function. Thus, present study was aimed to note seasonal and sex dependent variation in free radical status in Indian goat Capra hircus under the aegis of melatonin which is a well-known antioxidant. Methods: Markers of oxidative stress (i.e. Super Oxide Dismutase; SOD, Catalase; CAT, Glutathione Peroxidases; GPx) were measured by standardized protocols. Total Antioxidant Status (TAS) was measured by 2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid; ABTS) radical cation method and Lipid Per Oxidation (LPO) was measured by Thiobarbituric acid reactive substances (TBARS) level. Glucocorticoid Receptor (GR) expression in lymphoid organs was noted by Western Blot analysis. The circulatory level of cortisol and melatonin were estimated by commercial ELISA kits. Results: We noted significantly high levels of SOD, Catalase, GPx activities and ABTS level in lymphoid organs during monsoon and low during winter. Malonaldehyde; MDA a marker for lipid peroxidation was significantly high during summer and was significantly low during monsoon and winter. Cortisol level was significantly high during monsoon whereas melatonin level was significantly high during winter. GR expression was significantly high in males during monsoon and winter, but the level was significantly high only during monsoon in females. Conclusion: All the results suggest that monsoon and winter are the seasons of stress and to buffer the elevated stress level, melatonin coupled both the roles of free radical scavenger (as a free molecule) and elevation of antioxidant enzymes.