Effects of varying the fat content of a choline-devoid diet on promotion of the emergence of gamma-glutamyl-transpeptidase positive foci in the liver carcinogen-treated rats

Previous studies have shown that feeding a choline-devoid (CD) diet to rats is an effective promoter of liver carcinogenesis. In the present studies, we investigated the effects of CD diets containing different levels of fat (high, 15%; low, 4%) on the induction of foci of gamma-glutamyltranspeptidase (GGT) positive hepatocytes in the liver of rats initiated with a single dose of diethylnitrosamine. In rats fed the high-fat CD diet for 4--6 weeks, a greater number of foci was induced than in rats fed similarly the low-fat CD diet. However, liver DNA synthesis and the rate of hepatocyte mitosis were not significantly different in rats fed the 2 CD diets, but were significantly higher than in rats fed a choline-supplemented diet. These results indicate that beside stimulation of liver cell proliferation, other factor(s) determine the efficacy with which a CD diet exerts its promoting action.