Effect of deficiencies of selenium and vitamin E alone or in combination on the induction of mammary carcinogenesis by 1-methyl-1-nitrosourea.
Experiments were conducted to determine the dietary levels of selenium and vitamin E that could be fed chronically to induce a deficiency of one or both nutrients. It was observed that diets containing less than 0.02 mg Se/kg and 3 IU vitamin E/kg induced a deficiency without drastically altering growth performance or survival. Once established, these dietary conditions were used to investigate the effect of single or combined deficiencies of selenium and vitamin E on the promotion phase of mammary carcinogenesis induced by 1-methyl-1-nitrosourea (MNU). In the carcinogenesis experiment, 21 day old female Sprague-Dawley rats were fed a torula yeast formulated diet deficient in selenium and vitamin E until they were 50 days of age. At that time, each rat was injected i.p. with 12.5 mg MNU/kg body weight. Seven days thereafter, rats were randomly assigned to one of four treatment groups that were deficient or adequate in selenium and/or vitamin E. The experiment was terminated 30 weeks after carcinogen treatment. In comparison to rats fed the adequate diet, final cancer incidence and number were higher and cancer latency shortened in rats consuming the diet deficient in both selenium and vitamin E. Single deficiencies of either nutrient failed to significantly alter the tumorigenic response.
Laboratory of Nutrition Research, AMC Cancer Research Center, Denver, CO 80214.
H J
HJ
Thompson
D000704:Analysis of Variance; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001835:Body Weight / Q000187:drug effects; D004032:Diet / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005260:Female; D005979:Glutathione Peroxidase / Q000032:analysis; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced*; D008770:Methylnitrosourea; D051381:Rats; D011919:Rats, Inbred Strains; D012044:Regression Analysis; D012643:Selenium / Q000172:deficiency / Q000494:pharmacology*; D014811:Vitamin E Deficiency / Q000150:complications*
D000975:Antioxidants; D008770:Methylnitrosourea; D005979:Glutathione Peroxidase; D012643:Selenium