EFFECT OF ZINC ON LIPID-PEROXIDATION AND ANTIOXIDANT ENZYMES IN HEPATIC AND BRAIN-TISSUES OF CHICK-EMBRYOS

Chick embryos were treated with different concentrations (25 and 75 mu moles/kg egg wt.) of zinc on the 14th day of embryonic development. T he levels of thiobarbuturic acid reacting substances (TEARS), glutathi one (GSH) and activity levels of antioxidant enzymes such as glutathio ne peroxidase (GPx), glutathione reductase (GR), glutathione-S-transfe rase (GST), superoxide dismutase (SOD) and catalase were measured in b oth hepatic and brain tissues after different time intervals (24 h, 72 h and 120 h) of zinc exposure. Increased levels of TEARS were observe d after 24 h of zinc treatment and thereafter (72 h and 120 h) the lev els were decreased in both the tissues. Significant induction was obse rved in antioxidant enzyme activities in both the tissues after 24 h a nd 72 h when compared to 120 h. However, the GSH levels were increased at 24 h and 72 h and thereafter decreased in both the tissues at 120 h. The elevated levels of antioxidant enzymes at 24 h and 72 h may be responsible for the reduction of TEARS at 72 h and 120 h in developing chick embryos.