The Influence of Adrenal Injury Produced in Rats by 7,12-Dimethylbenz[α]anthracene on the Regulation of Liver Tyrosine Aminotransferase and Tryptophan Oxygenase

The morphologic damage to the adrenals and the behavior of 2 liver enzymes (tyrosine aminotransferase and tryptophan oxygenase) that are regulated by the adrenals were studied in 2 strains of rats treated with 7,12-dimethylbenzl[α]anthracene at 50 days of age. The induction of these enzymes by reserpine, acting through the pituitary-adrenal system, was used as a measure of the ability of the adrenals to secrete glucocorticoids. In both strains of rats, the adrenocortical damage was maximal and the enzyme response to reserpine was minimal 3 days after the administration of 7,12-dimethylbenz[α]anthracene, thus providing a correlation between the histopathologic changes and the function of the adrenal glands. The initial stresslike effect of 7,12-dimethylbenz[a]anthracene on the liver enzymes, seen at 5 hr, was smaller in the Sprague-Dawley rats in which 7,12-dimethylbenz[a]anthracene caused a higher tumor incidence. The basal enzyme levels and their induction by reserpine were also lower in these rats than in NEDH rats. These differences between the 2 strains diminish with age, which suggests that at the critical age of 50 days when the carcinogen is administered, the pituitary-adrenal system may be less fully developed in the Sprague-Dawley strain which has the higher tumor incidence.