Interaction of selenium deficiency and fat intake in the regulation of enzymes associated with peroxide metabolism

Abstract

The present study was designed to examine the effect of selenium deficiency on the activities of heme hydroperoxidase and glutathione peroxidases in the liver of male rats maintained on either a 5% or a 25% corn oil diet and treated with phenobarbital. Our results showed that although the basal levels of cytochrome P-450 and heme hydroperoxidase were unaffected by selenium deficiency, the magnitude of phenobarbital induction was impaired because of the depletion of this trace element. This effect was accentuated especially in rats with a high-fat intake. Selenium deprivation resulted in a virtual disappearance of glutathione peroxidase activity when assayed with hydrogen peroxide, because of depletion of the selenium-dependent enzyme. In contrast, only a 60% reduction in glutathione peroxidase activity was observed when assayed with cumene hydroperoxide. Phenobarbital administration was found to increase the activity of the latter only. Unlike the situation with the hemoprotein, dietary fat had no influence on either the basal or stimulated glutathione peroxidase activities, regardless of the selenium status of the animals.