Effects of Dietary Selenium and Vitamin E on Hepatic Mixed-Function Oxidase Activities and In Vivo Covalent Binding of Aflatoxin B1 in Rats

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Abstract
Male weanling Fischer-344 rats were fed a selenium (Se)-vitamin E (VE) deficient Torula ycast basal dict or that dict supplemented with graded levels of Se (0.2–6.0 ppm as Na2SeO3) or VE (100 iu/kg as all-rac-2-tocopheryl acetate), or both, for 4 or 6 weeks. Se deficiency and excess (6.0 ppm) markedly depressed in vivo covalent binding of aflatoxin (AFB1) to macromolecules in livers of rats killed 2 hours after an i.p. dose of 1 mg/kg tritiated AFB1. VE supplementation had no effect. Prior phenobarbital (PB) treatment generally decreased adducts without changing diet-related trends. Some hepatic enzyme capabilities were also measured. Cytochrome b3 content and cytochrome c reductase activity were unaffected by diet. VE increased cytochrome P-450 content, ethylmorphine N-demethylase and benz(α)pyrene hydroxylase activities; all these were unaffected by Se levels. Se deficiency and excess (but not VE deficiency) increased glucuronyl transferase. PB induction affected all diet groups and was more in agreement with MFO activity than transferase. Adduct formation was more consistently related to transferase activity than to MFO activities. The contrasting effects of SE and VE on AFB1 adducts in rats and chicks are discussed.