EFFECTS OF MISO AND NACL ON THE DEVELOPMENT OF COLONIC ABERRANT CRYPTFOCI INDUCED BY AZOXYMETHANE IN F344 RATS

The present study was designed to investigate the effects of dietary m ise and NaCl supplementation on the development of aberrant crypt foci (ACF) induced by azoxymethane (AOM) in male F344 rats. A total of 76 rats, six weeks of age, were divided into seven groups and given weekl y subcutaneous injections of AOM (15 mg/kg body wt) for three weeks to induce ACF. The animals were placed on diets one week before the firs t AOM dosing. Group 1 was fed a normal diet as a control. Groups 2-4 w ere fed diets containing 5%, 10%, and 20% miso, respectively, and Grou ps 5 and 6 were fed diets containing 2.2% and 4.4% NaCl, respectively, for five weeks. Group 7 was fed a normal diet without carcinogen expo sure. Dietary mise inhibited the development of ACF in a dose-dependen t manner (y = -3.9x + 140, r = -0.94). Thus the mean numbers of ACF pe r colon were significantly lower in Groups 3 and 4 than in Group 1 (p < 0.01), and there were fewer aberrant crypts per colon in Group 4 tha n in Group 1. NaCl supplementation was associated with fewer ACF, but this was not statistically significant. 5-Bromo-2'-deoxyuridine labeli ng indexes in the colonic epithelium were significantly lower in Group 3 than in Group 1 (p < 0.05). The present results indicate that dieta ry mise could act as a chemopreventive agent for colon carcinogenesis.