The fate and acute toxicity of aflatoxin B 1 in the mastomys and rat

Abstract

The fate and acute toxicity of aflatoxin B 1 (AFB 1) were studied in the mastomys ( Praomys coucha) and compared with Fischer rats. The experiment regarding the fate of [ 3H]AFB 1 showed that the radioactivity was excreted mainly through the feces, more rapidly in the mastomys than in the rat, regardless of whether [ 3H]AFB 1 was given orally or intravenously. The levels of radioactivity bound to the liver DNA were lower in the mastomys than in the rat, indicating that the levels of AFB 1 binding to the macromolecules in the liver were lower in the mastomys. Consistent with such differences in the fate of AFB 1 between the two species, the mastomys were far more resistent to the acute effects of AFB 1 than were the rats. Oral administration of AFB 1 at a dose of 1.0 mg/kg to rats caused marked microscopic changes in the liver, involving hepatic necrosis and proliferation of bile ducts, but at a dose of 4.0 mg/kg to mastomys caused no pathological changes in the liver or kidneys, and at a dose of 10.0 mg/kg caused only glycogen deposition in hepatic cells in a limited area. The observed differences in susceptibility to the toxic effects of AFB 1 and in the fate of AFB 1 between the two species are in accord with our previous finding that liver cytosol in the mastomys inhibits microsome-mediated AFB 1-DNA binding in vitro more strongly than in rat liver.