Abstract

We investigated the possibility that norepinephrine from the human ovary is released after nerve stimulation and that this neurotransmitter is coupled to a steroidogenic response. Biologically significant levels of both norepinephrine and dopamine were found in human ovarian biopsies. [3H]norepinephrine incorporated in vitro was readily released by electrical stimulation in a Ca2+-dependent process. Ovarian membrane preparations exhibited specific binding sites for the ?-adrenergic antagonist [3H]dihydroalprenolol. Displacement of [3H]dihydroalprenolol with zinterol (a specific ?2-agonist) indicated that 72% of these sites were type ?2-receptors. ?-receptors were also present on granulosa cells. Stimulation of granulosa cells with luteinizing hormone or the ?-agonist isoproterenol increased the release of progesterone after 4 d in culture. These results suggest that the sympathetic nerves present in human ovary are coupled to ?-adrenergic receptors present in endocrine cells and, as in nonprimate mammals, appear to participate in the regulation of ovarian function.