The role of ACTH in placental steroidogenesis

We have studied the possible function of the placental adrenocorticotrophic hormone-(ACTH-) like substance (PALS) in placental steroidogenesis by measuring oestradiol (E2) and progesterone (P4) in term human placental explants incubated with commercially available porcine ACTH I-39. There was a dose-dependent increase in the E2 and P4 released into the medium at 24 h as compared to controls. At 48 h, no significant effect was noted. Propranolol (10(-5) M) did not block the effect of ACTH on P4 release. The data suggest that ACTH may have a regulatory role on placental steroidogenesis. The possible mechanisms of action of PALS on the placenta and the adrenal are discussed, and the role of PALS in the maintenance of pregnancy and in maternal response to stress is suggested.