Effects of dietary fat level and dimethylhydrazine on fecal acid and neutral sterol excretion and colon carcinogenesis in rats
Reddy, B.S.; Weisburger, J.H.; Wynder, E.L.
Journal of the National Cancer Institute 52(2): 507-511
1974
ISSN/ISBN: 0027-8874 PMID: 4816006 Document Number: 81106
Weanling male Fischer rats were fed on isocaloric 25% casein diets in which the fat content was 20, 4 or 0.5%; the fat content was adjusted at the expense of sucrose. When 7 weeks old the rats were given weekly subcutaneous injections of 1,2-dimethylhydrazine (DMH) 10 mg/kg bodyweight or 0.9% NaCl solution. Sterol balance studies were made after 18 weeks and the rats were killed after 20 weeks of injection. The high-fat diet increased acid and neutral sterol in faeces; acid sterols in faeces were more extensively degraded in rats on the high-fat than in those on the normal or low-fat diet. Compared with controls, rats treated with DMH excreted larger amounts of acid and neutral sterols, and bacterial modification of intestinal acid sterols increased. Rats on the high-fat diet were more susceptible to colon tumour induction by DMH than rats on low- or normal-fat diet or Purina Laboratory Chow.