Effect of types and amount of dietary fat during the initiation phase of hepatocarcinogenesis
2001
Rahman, K.M.W. | Sugie, S. | Tanaka, T. | Mori, H. | Reddy, B.S.
The effects of various levels of corn oil and lard fed during the initiation stage of azoxymethane (AOM)-induced hepatocarcinogenesis were studied in male Fischer 344 rats. The animals were fed diets containing 5%, 13.6%, and 23.5% corn oil or lard two weeks before, during, and until one week after injections of AOM (15 mg/kg body wt sc) once weekly for two weeks. One week after AOM treatment, groups of animals fed the 13.6% and 23.5% corn oil or lard diet were transferred to their respective 5% corn oil or lard diet and fed these diets until the termination of the study (34 wk). Immunohistochemical staining of glutathione S-transferase placental form was performed in the liver, and the number of glutathione S-transferase placental form-positive foci was determined. Density, average area, and unit area of foci were significantly inhibited in the animals fed the 13.6% and 23.5% lard diets compared with those fed the 13.6% and 23.5% corn oil diets. These results indicate that the effect of dietary fat during the initiation phase of AOM-induced hepatocarcinogenesis depends on the type of fat and its fatty acid composition. Additionally, the enhancing effect of a corn oil diet in hepatocarcinogenesis is mainly present during the initiation phase of carcinogenesis compared with a lard diet.
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