In vivo changes in antioxidant system and protective role of selenium in chlorpyrifos-induced subchronic toxicity in bubalus bubalis

Chlorpyrifos, an organophosphate, is one of the widely used insecticides for control of pests in various agricultural and animal husbandry operations. The objective of the present investigation was to assess the effect of subchronic exposure of chlorpyrifos on the antioxidant status of buffalo calves and to perceive the role of selenium in cases of chlorpyrifos toxicity. Chlorpyrifos at a dose rate of 0.05 mg/kg per day for 20 consecutive weeks, significantly elevated the enzymic activity of glutathione peroxidase (GPx) (54.8%), glutathione reductase (GR) (79.4%), glutathione-S-transferase (GST) (34.2%), glucose-6-phosphate dehydrogenase (G6PD) (33.2%), superoxide dismutase (SOD) (19.3%) and catalase (CAT) (63.8%). The altered antioxidant status was well evident from the depleting glutathione levels and a two-fold rise in the extent of lipid peroxidation. Supplementation of selenium in the form of sodium selenite @ 0.05 mg/kg per day for 20 weeks in chlorpyrifos intoxicated calves had a marked beneficial effect on the overall antioxidant potential of the animals as evident by no significant alteration in the extent of lipid peroxidation, levels of blood glutathione and activities of various antioxidant enzymes viz. GST, GR, SOD, CAT and G6PD. There was only a significant increase in the activity of GPx to the tune of 27.4%. Therefore, on the basis of the present investigation it can be suggested that oxidative stress is one of the main mechanism involved in chlorpyrifos toxicity and supplementation with sodium selenite in such cases can have significant beneficial and therapeutic effects.