DIFFERENT STARTING TIMES OF ALPHA-TOCOPHEROL AND GAMMA-TOCOTRIENOL SUPPLEMENTATION AND TUMOR-MARKER ENZYME-ACTIVITIES IN THE RAT CHEMICALLY-INDUCED WITH CANCER

1. alpha-Tocopherol ((alpha-T) and gamma-tocotrienol (gamma-T) were su pplemented continuously for 8 weeks in the diets of normal rats and ra ts chemically induced with cancer using diethylnitrosamine (DEN), 2-ac etylaminofluorene (AAF) and partial hepatectomy. Hepatocarcinogenesis was followed by determining the plasma gamma-glutamyl-transpeptidase ( GGT) and alkaline phosphatase (ALP) activities as well as placental gl utathione S-transferase (POST) and GGT activities histochemically, at 4-week intervals. 2. Male Rattus norvegicus were supplemented alpha-T and gamma-T at two different doses of 30 and 300 mg/kg diet. The suppl ementation was started at three different times: simultaneously with D EN administration; 4 weeks; and 8 weeks after DEN administration. 3. E levation of plasma GGT activities and formation of PGST and GGT positi ve foci were attenuated significantly (P < 0.05) when alpha-T and gamm a-T were supplemented simultaneously with cancer induction. Supplement ation begun 4 and 8 weeks after cancer induction did not affect plasma enzyme activities and formation of enzyme-positive foci. 4. alpha-T w as more effective than gamma-T, and a lower dose of 30 mg/kg was found to be more effective in reducing the severity of hepatocarcinogenesis . (C) 1997 Elsevier Science Inc.