ENHANCEMENT OF MAMMARY CARCINOGENESIS BY A HIGH-FAT DIET IN FISCHER, LONG-EVANS, AND SPRAGUE-DAWLEY RATS

Abstract

The relationship between dietary fat and mammary carcinogenesis was examined by feeding a high-fat or a low-fat purified diet, differing only in fat and carbohydrate content, to Fischer, Long-Evans and Sprague-Dawley rats. An additional group of rats from each strain was fed a nonpurified laboratory diet for comparison. The rats were given an i.v. dose of N-nitrosomethylurea (50 mg/kg body wt) at 50 days of age. A high-fat purified diet significantly enhanced mammary carcinogenesis; a nonpurified laboratory diet retarded mammary carcinogenesis compared to a low-fat purified diet. Rats on 3 different diets had a similar body weight gain. The susceptibility to N-nitrosomethylurea-induced mammary carcinogenesis in the rats was in the order of Sprague-Dawley > Fischer > Long-Evans. Fischer rats appeared to be better suited for further systematic studies of dietary fat and mammary carcinogenesis.