Effects of Adrenocorticotropin and Insulin on Carcinogenesis in Hypophysectomized Rats2

Abstract

The administration of adrenocorticotropin and insulin to hypophysectomized rats fed 0.06 percent 3′-methyl-4-dimethylaminoazobenzene resulted in the highest incidence of liver tumors yet observed in the study of the effects on carcinogenesis of hormone replacement after hypophysectomy. The gross and histological precancerous changes observed in these animals appeared similar to those occurring in intact animals, which indicates that administration of the hormones had restored the same sequence that produces liver cancer in the intact rat. The liver concentrations of deoxyribonucleic acid, ribonucleic acid and riboflavine were also determined. In contrast to rather definite patterns observed in intact rats fed diets containing the carcinogen, there were no consistent or predictable changes observed in the livers of the hypophysectomized rats treated with adrenocorticotropin and insulin. The relative importance of the pituitary-gland in cancer induction by fluorenamines and azo dyes is discussed.