EFFECTS OF VARIOUS CONCENTRATIONS OF ETHYL-ALPHA-P-CHLOROPHENOXYISOBUTYRATE (CLOFIBRATE) ON DIETHYLNITROSAMINE-INDUCED HEPATIC TUMORIGENESIS IN THE RAT

Male F344 rats were given diethylnitrosamine in drinking water at a concentration of 40 ppm for 5 wk. One week later, the rats were fed a diet containing clofibrate at concentrations of 0, 0.1, 0.25, 0.5 and 1% for 19 wk. Hepatic tumors > 1 mm were counted. The doses of 0.1% and 0.25% clofibrate markedly enhanced the incidence of hepatic tumors, whereas 0.5% clofibrate had no effect and 1% clofibrate markedly inhibited hepatocarcinogenesis. The lower doses of clofibrate (0.1% and 0.25%) promote heptaocarcinogenesis. The higher doses of clofibrate (0.5% and 1%) depress weight gain by lowering the intake of food. This lowered food intake might contribute to inhibition by hepatocarcinogenesis.