Changes in Oxidative Stress and Antioxidant Status in Stressed Fish Brain

Toxic pollutants entering into aquatic environment exert their effect through altering redox cycling in fish. The antioxidant defence as well as oxidative damage is a common effect in fish exposed to xenobiotics in their water body. Brain requires high and constant oxygen supply to meet its energy needs and generates more free radicals per gram of tissue than does any other organ in the body. The present study evaluates the effects of environmental contaminants on stress biomarkers in brain tissue of Mugil cephalus. Effects of xenobiotics on the brain of M. cephalus is evaluated in terms of lipid peroxides (LPO), protein carbonyls (PC), nitrite (NO2), 3-Nitrotyrosine (3NT), reduced glutathione (GSH) and total antioxidant capacity (TAC). There was a significant increase in the level of LPO (2 fold), PC (27%), NO2 (1 fold), 3-NT (p<0.001) alongwith significant decrease of GSH (59%) and TAC (75%) in brain of M. cephalus inhabiting Ennore estuary than Kovalam estuary. In conclusion, reduction in the level of TAC and GSH indicate that pollutants in water body exert their effect through oxidative/nitrative stress. The damaged products through stress can persist in the organism leading to changes at molecular level in fish which may ultimately affect their survival.