Fetal rat adrenal gland steroidogenesis in vitro in prolonged pregnancy.

Progesterone, injected into pregnant rats on the last days of pregnancy, prolonged pregnancy and prevented parturition. The fetuses from mothers whose pregnancies were prolonged have greater body and adrenal weights on days 23 and 24 of gestation as compared with 1- and 2-day-old rats. The adrenal glands of fetuses and neonatal rats converted in vitro 4-(14)C-progesterone to 11-deoxycorticosterone (DOC), corticosterone (B), 18-hydroxy-11-deoxycorticosterone (18-OH-DOC), 18-hydroxy-corticosterone (18-OH-B) and aldosterone. The fetal adrenal glands on the 23rd and 24th day of pregnancy synthesized in vitro less DOC, corticosterone and 18-OH-DOC than the adrenal glands of intact neonatal rats. These results demonstrated that progesterone in prolonged pregnancy inhibited enzymes of steroid hydroxylation which converted progesterone to DOC, corticosterone and 18-OH-DOC in fetal rat adrenal glands.