ACTIVATION BY CORTICOSTEROIDS OF STEROID METABOLIZING ENZYMES IN OVINE PLACENTAL EXPLANTS IN VITRO

Abstract

A technique has been developed for the study of placental steroid synthesis in tissue culture. Explants of sheep placentas recovered in the last third of gestation produced progesterone and converted labelled androstenedione into unconjugated and conjugated oestrogens. Cortisol added to the medium stimulated 17α-hydroxylase and aromatizing enzyme activities. The results are discussed in relation to the proposal that the rise in secretion of fetal cortisol before parturition has a direct effect on the activation of placental enzymes catalysing the conversion of progesterone to oestrogens.