Effect of sub-chronic selenium toxicosis on lipid peroxidation, glutathione redox cycle and antioxidant enzymes in calves.

The present investigation reports the effect of sodium selenite-induced sub-chronic toxicity in crossbred cow calves on various antioxidant enzymes. Sodium selenite (0.25 mg/kg for 16 w) resulted in characteristic signs of sub-chronic selenosis, ie alopecia, cracking and enlargement of hooves, interdigital lesions, ring formation on the coronet region, and gangrene at tip of the tail. The sodium selenite resulted in significant rise of blood selenium levels and concurrent increase in erythrocytic glutathione peroxidase (GPx) activity. Blood selenium levels and GPx activity had a high positive correlation (r = 0.97). Blood glutathione levels were lowered from 211.1 +/- 13.4 to 95.56 +/- 11.8 microg/ml. Selenosis caused oxidative stress as evidenced by a 3-fold increase in lipid peroxidation: activities of glutathione-S-transferase, glutathione reductase, superoxide dismutase and catalase were significantly increased. These findings support the hypothesis that the pro-oxidant attributes of selenium play important roles in its toxicity.