RESUMO
This study was conducted to examine the effects of dietary grape extracts on preneoplastic foci formation in rat hepatocarcinogenesis, and related hepatic enzymes. Male Sprague-Dawley rats were fed basal diet or grape diet containing 15% concentrated grape extracts (68 bricks). The grape diet groups were divided into whole-period grape diet group (DEN-GW; grape diet group fed throughout experimental period) and postinitiation grape diet group (DEN-GP; grape diet group fed from post initiation stage) according to the starting time point of the grape diet. Hepatocarcinogenesis was induced by diethylnitrosamine (DEN; 200 mg/kg bw) and 2/3 partial hepatectomy (DEN-B; DEN-treated basal diet group, DEN-GW, and DEN-GP groups), while the control group treated with saline and sham operation (Control group). The formation of placental glutathione (GSH) S-transferase positive (GST-P(+)) foci in DEN-GW group was moderately but significantly suppressed, however, not in DEN- GP group. Thiobarbituric acid reactive substances content of DEN-GW group was significantly lower than that of DEN-B group. The activity of fatty acid synthase (FAS) in the grape diet groups was decreased about 1/2 of the DEN-B group. The content of GSH and GSH peroxidase activity were increased by carcinogen treatment, but not modulated by grape diet. The activities of GSH S-transferase, p-nitrophenol hydroxylase, and catalase were not affected by diet or treatment. Conclusively, the grape diet-induced reduction of FAS activity that was expressed highly in neoplastic tissues, might be one of the contributing mechanisms of hepatic cancer prevention.