The Effect of Certain Carcinogens on Vitamin A in the Liver

Abstract

Colloidal dibenzanthracene, injected intraperitoneally, increased the rate of depletion of hepatic vitamin A fourfold, and also appeared to interfere with the entry of vitamin A to the liver. Dibenzanthracene injected subcutaneously in oil also increased vitamin A depletion. Methyl cholanthrene and benzpyrene, two potent carcinogens, and 1, 2 benzanthracene, a non-carcinogenic hydrocarbon, likewise reduced hepatic vitamin A, but all three were quantitatively less effective than dibenzanthracene. There was therefore no correlation between the carcinogenicity of a compound and its effect on vitamin A. Butter yellow, which is carcinogenic, and carbon black, which is noncarcinogenic, were without effect on the vitamin. The livers of rats with spontaneous tumors contained more vitamin A than the livers of non-tumorous controls. Livers of rats with tumors due to methyl cholanthrene contained more vitamin A than non-tumorous rats treated with dibenzanthracene. Decreased vitamin A, therefore, is not a necessary prerequisite to tumor formation.