Regulation of expression of antioxidant enzymes by vitamin E and curcumin in L-thyroxine-induced oxidative stress in rat renal cortex.

The present study investigates the antioxidative effects of vitamin E and curcumin against L-thyroxine (T(4))-induced oxidative stress in renal cortex of adult male rats. Rats were made hyperthyroid by administration of L-thyroxine (0.0012%) in their drinking water for 30 days. Vitamin E (200 mg/kg body weight/day) and curcumin (30 mg/kg body weight/day) were supplemented singly or in combination orally for 30 days along with L-thyroxine treatment. The elevated level of oxidative stress parameters (lipid peroxidation and protein carbonylation) and decline level of small antioxidant molecules (reduced glutathione and ascorbic acid) in renal cortex of T(4)-treated rats were restored back by supplementation of vitamin E or/and curcumin. Increased superoxide dismutase and catalase activities in kidney cortex of T(4)-treated rats were ameliorated in response to vitamin E or/and curcumin treatment. The elevated translated product of Cu/Zn-SOD, Mn-SOD and catalase in T(4)-treated rats were differentially reduced by the administration of vitamin E and curcumin independently or in combination. Cu/Zn-SOD expression was ameliorated by both vitamin E and curcumin independently or in combination, whereas Mn-SOD expression was ameliorated by the supplementation of vitamin E or curcumin independently. However, the expression of catalase was alleviated by only supplementation of vitamin E to T(4)-treated rats. The results suggest that both vitamin E and curcumin may play an important role in protecting T(4)-induced oxidative stress in rat renal cortex by differentially modulating the activities of antioxidant enzymes and oxidative stress parameters.