[Effects of glucocorticosteroids on enzymatic activity in the urea cycle in fetal rat liver].

The five urea cycle enzyme activities of rat liver are followed during late fetal period and the first day of life. All five enzymes exhibit relatively low activities in foetal liver and a rapid postnatal increase. Lack of glucocorticosteroid (after hypophysectomy in utero) induces an important decrease of activity of three enzymes: carbamyl phosphate synthetase, ornithine transcarbamylase and argininosuccinate synthetase. Treatment with hydrocortisone acetate on decapitated fetuses results in a marked stimulation of the activity of four of the enzymes: carbamyl phosphate synthetase, ornithine transcarbamylase, argininosuccinate synthetase and arginase. Premature induction of carbamyl phosphate synthetase activity is obtained after intraperitoneal injection with hydrocortisone acetate at 16,5 days of gestation.