Human chorionic gonadotropin-mediated glycogenolysis in human placental villi: A role of prostaglandins

The acute "in vitro" effects of human chorionic gonadotropin (HCG) and protaglandin E2 on human placental glycogen metabolism have been studied in immature placental villi in short-term culture. HCG elicited within 15 min of culture, an acute glycogenolytic response in placental tissue which included a decrease in placental glycogen, an activation of the glycogen phosphorylase enzyme system and a pronounced elevation in the cyclic AMP concentration of the placenta. The presence of prostaglandin E₂ in the culture medium evoked a similar glycogenolytic effect in immature human placental villi including the increase in tissue cyclic AMP levels. These findings suggest a second messenger role of the prostaglandins in HCG action and results are discussed in light of the mechanism of action of HCG on the human placenta.