Effect of endosulfan on antioxidants of freshwater fish Channa punctatus Bloch: 1. Protection against lipid peroxidation in liver by copper preexposure

Effect of a single exposure of endosulfan (5 ppb) on catalase (CAT), glutat hione peroxidase (GPx), glutathione S-transferase (GST), and reduced glutat hione (GSH) of liver, kidney, and gill of a freshwater fish (Channa punctat us Bloch) were evaluated after 24 h of treatment. Endosulfan exposure resul ted in a significant induction (p < 0.05-0.001) of GPx, GST activity, and G SH levels in all the organs. However, CAT activity was found to be signific antly decreased (p < 0.01-0.001). Lipid peroxidation (LPO) values were also determined in liver, kidney, and gill and a significant increase in LPO va lues (p < 0.05-0.01) was observed in all the organs. We also investigated w hether preexposure to low concentration of copper (10 ppb) for 4 weeks has any protective effect against endosulfan-induced oxidative damage. In coppe r-acclimatized endosulfan-exposed fish, a significant decrease in GPx (p <l ess than> 0.001), GST (p < 0.05), GSH (p < 0.001) levels, and LPO (p < 0.01 ) was observed in the liver, whereas CAT activity was increased significant ly (p < 0.001). However, kidney and gill did not show any significant alter ations in antioxidant levels. The results of this study demonstrate that en dosulfan induces peroxidative damage in liver, kidney, and gill in response to which levels of antioxidant were modulated. However, when fish preaccli matized to copper were exposed to endosulfan, protection a against oxidativ e damage was observed only in the liver. It is proposed that measurement of antioxidants in fish tissues may prove to be useful in biomonitoring of ex posure to aquatic pollutants.