Effects of adrenalectomy on gonadal hormone-induced changes in hepatic microsomal carboxylesterase activities in rats

Hepatic microsomal carboxylesterase (E.C. 3.1.1.1) showed a different capacity for the hydrolysis of various substrates in rats. Adrenalectomy in castrated male rats slightly decreased the activities towards p-nitrophenyl-acetate and malathion. The magnitude of testosterone-induced changes in the hydrolase activities by liver microsomes in adrenalectomized-castrated male rats was markedly decreased castrated male rats. However, when 5 alpha-dihydrotestosterone was administered to adrenalectomized-castrated male rats, malathion and p-nitrophenylacetate hydrolase activities were significantly increased. But in all cases, isocarboxazid and acetanilide hydrolase activities were not affected by physiological states. These results suggest that hepatic microsomal carboxylesterases may be, at least in part, regulated by adrenal gland and gonadal hormones which exert different effects on the several isozymes of carboxylesterases.