LEAD-INDUCED LIPID-PEROXIDATION AND ANTIOXIDANT DEFENSE COMPONENTS OF DEVELOPING CHICK-EMBRYOS

Administration of lead (1.25 and 2.5-mu-mol/kg egg weight) to 14-day-old chick embryos enhanced the level of lipid peroxides (LPO) in tissues of liver, brain, and heart. Accumulation of LPO was maximum at 9 h after treatment with lead and returned to normal level by 72 h. Further, we have studied the levels of glutathione-S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase. At 9 h posttreatment, the hepatic GR was reduced significantly with the induction of GST and considerable depletion of GSH. However, in brain and heart, both GR and GST activities were unaltered with significant reduction of GSH. Further. an increase of non-Se-dependent GPx and SOD activities were observed in liver, brain, and heart. Similarly, at 72 h. although the GPx activity was found decreased in liver and brain, the GST, catalase, and SOD activities were significantly increased in all the three tissues alike, suggesting tissue-specific changes of antioxidant defense components in response to lead treatment. Our results suggest that the elevated levels of GST, SOD, and catalase at 72 h were successful in bringing LPO levels back to normal.