The role of catecholamines in estradiol and progesterone secretion by cultured explants and cells of human term placentae.

The effects of physiological concentrations of the native catecholamines norepinephrine and epinephrine upon term placental hormonal function were examined by measuring estradiol and progesterone secretion by organ and cell culture systems. Results show that, in explants, both catecholamines caused a significant increase in the secretion of both sex steroids, p less than 0.05. Estradiol secretion was blocked by the alpha and beta adrenergic receptors antagonists, phenoxybenzamine and propranolol, respectively, p less than 0.05. Norepinephrine but not epinephrine dependent progesterone secretion was blocked by propranolol. In cells, epinephrine stimulated cyclic AMP generation and caused a 30% increase in estradiol secretion, p less than 0.05. Both were abrogated by propranolol. Norepinephrine increased secretion by 25%, p less than 0.05. This was inhibited by yohimbin and prazosin, alpha-1 and -2 receptors antagonists, respectively. In conclusion, the placenta in vitro is a target organ for catecholamines. The marked response of the explant system as compared with the marginal response of the cell culture system indicates that cell to cell contact/communication is required for full expression of catecholamine effect.