Effect of vitamin E on the induction and evolution of enzyme-altered foci in the liver of rats treated with diethylnitrosamine.

Abstract

The effects of dietary vitamin E (VE) on the steps of hepatocarcinogenesis, the induction and growth of gamma-glutamyltranspeptidase (GGT)-positive foci and their evolution into persistent nodules, were analyzed in the liver of rats treated with diethylnitrosamine (DEN). The induction of GGT-positive foci was inhibited by a diet containing 0.36-1.5% VE given after initiation with 200 mg/kg body weight (b.w.) DEN for 6 weeks with partial hepatectomy (PH) on week 3. The numbers and areas of GGT-positive foci were enhanced by diets containing 0.36 and 0.72% VE, given for 1 week after initiation with 10 mg/kg b.w. DEN and PH, followed by selection by 0.02% 2-acetylaminofluorene (AAF) and carbon tetrachloride (CCl4), but these were not enhanced by a diet containing 1.5% VE. Remodeling of hyperplastic nodules was not affected by the diet containing 0.72% VE given after initiation with DEN and selection for 12 weeks. The staining characteristics of GGT were different between remodeling and persistent nodules, except for those of the glutathione-S-transferase placental form (GST-P). The results obtained suggest that VE could prevent the very early events during hepatocarcinogenesis, the induction of phenotypically altered foci, but could no longer affect the later stages, the evolution of foci into persistent nodules.