EFFECTS OF A HIGH-FAT DIET ON AZOXYMETHANE-INDUCED ABERRANT CRYPT FOCI AND FECAL BIOCHEMISTRY AND MICROBIAL ACTIVITY IN RATS

To shed light on the association of dietary fat with the development o f colon cancer, we studied the ability of azoxymethane (AOM) to induce aberrant crypt foci (ACF) and biochemical changes in rats fed high- o r normal-fat diets. Sir-week-old male Fischer 344 rats were placed on a high-fat [7% (wt/wt) soybean oil + 15% (wt/wt) beef tallow] or a nor mal-fat (7% soybean oil, AIN-93G) diet. Rats fed each of these diets w ere given two weekly subcutaneous injections of AOM(15 mg/kg body wt) or saline at seven and eight weeks of age. Fecal samples were obtained at 10 weeks of age, and animals were sacrificed for ACF scoring and a nalysis of-cecal contents at 13 weeks of age. We observed greater numb ers of ACF in the high- than in the low-fat group. Biochemically, rats fed the high-fat diet showed dramatically elevated fecal and cecal lo ng-chain free fatty acid levels and intestinal alkaline phosphatase ac tivity. These animals also showed increased cholesterol and decreased coprostanol levels. We did not detect significant differences in the f ecal and cecal concentrations of total and soluble bile acids or total neutral sterols (cholesterol + coprostanol) between the two groups. T hus a high-fat diet does show certain striking effects on colon bioche mistry in rats.