The effect of isolation stress on some hepatic drug and carcinogen metabolising enzymes in rats.

Rats were subjected to stress by isolation for periods of up to eight days, which produced an elevation in plasma cortisol. In vivo drug metabolism as estimated by the plasma elimination rate of orally-administered antipyrine was not significantly affected by this treatment although there was an apparent decrease in the absorption rate of the drug. In vitro experiments on hepatic microsomal preparations derived from stressed animals indicate that this stress increased in the activity of some enzyme systems concerned with benzo(a)pyrene activation and this correlated with an increased binding of the carcinogen to DNA. The activity of conjugating enzyme which could catalyze the excretion of such carcinogens was not significantly altered. The results indicated that stress could have an important bearing on carcinogenesis by enhancing to a greater extent enzyme systems responsible for activation than those involved in the excretion of polycyclic aromatic hydrocarbons.