IS ALPHA-TOCOPHEROL EFFECTIVE IN THE AMELIORATION OF CADMIUM-INDUCED THYROID-DYSFUNCTION

The ameliorating role of alpha-tocopherol on cadmium-induced thyroid d ysfunction with special reference to type I iodothyronine 5'-monodeiod inase (5'D-I) activity in mice liver was studied. Daily subcutaneous i njection of cadmium chloride (CdCl2, 1.0 mg/kg body weight) for 15 day s decreased serum triiodothyronine (T-3) and thyroxine (T-4) concentra tions and hepatic 5'D-I activity. However, cadmium (Cd) significantly increased lipid peroxidation (LPO), while the activities of antioxidan t enzymes, such as superoxide dismutase (SOD) and catalase (CAT), were decreased significantly. Simultaneous administration of alpha-tocophe rol (5 mg/kg body weight on alternate days) and Cd nearly restored thy roid function by maintaining normal hepatic 5 D-I activity and serum t hyroid hormone concentrations. It also prevented peroxidative membrane damage in liver as indicated by the maintenance of normal LPO. It app ears that cr-tocopherol maintained the activity of 5'D-I enzyme by pro tecting biomembranes from peroxidative damage.