The effects of selenium on the emergence of aflatoxin B1-induced enzyme-altered foci in rat liver.

The effects of selenium on the emergence of aflatoxin B1 (AFB1)-induced enzyme-altered foci were studied in male Sprague-Dawley rats. Animals were fed a selenium-deficient diet and supplemented with 5.0, 2.0, and 0.2, or 0 ppm selenium in drinking water for 3 weeks prior to initiation with 2.0 mumol/kg AFB1. After a 1-week period of selenium normalization, the animals were placed on a diet of ordinary rat chow, and were administered a promoting regimen of 500 ppm phenobarbital in drinking water for 1 week, after which time each rat received a two-thirds partial hepatectomy. The promoting regimen of phenobarbital in tap water was then reduced to 100 ppm and continued for 7 weeks. Subsequently, the rats were sacrificed, their livers excised, and fresh frozen sections prepared and stained histochemically to demonstrate areas of gamma-glutamyl transpeptidase (GGT) activity. Selenium supplementation was observed to diminish the induction of GGT-positive foci, especially at the 5.0-ppm level. These data suggest that selenium is able to protect against the hepatocarcinogenic effects of AFB1 in the rat, and that the enzyme-altered foci bioassay may be a useful technique in assessing the interaction of selenium on the process of hepatocarcinogenesis.