Influence of serotonin on progesterone and estradiol secretion of cultured human granulosa cells

ObjectiveTo explore the direct action of serotonin on progesterone (P) and estradiol (E2) secretion of human granulosa cells cultured in serum-free medium.DesignProgesterone and E2 production was measured in the presence and absence of serotonin, propranolol, or cycloheximide using radioimmunoassays; statistical analysis of the data was performed by ANOVA.SettingIn vitro fertilization and embryo transfer (IVF-ET) for infertility treatment at the University Women's Hospital, University of Tübingen, Germany.Patients, participantsFourteen women, 30 +/- 3 years old, undergoing IVF-ET.ResultsSerotonin stimulated a dose-related increase in P secretion with a maximal stimulatory effect at 10(-4) M. This response was blocked specifically by the beta-receptor antagonist propranolol (10(-4) M). Estradiol secretion in response to serotonin was dose-independent stimulation, which was highest at 10(-6) M and was inhibited by 10(-4) M propranolol. The protein synthesis inhibitor cycloheximide markedly reduced the stimulatory effect of serotonin on P secretion. Estradiol production in the presence of cycloheximide was significantly reduced; serotonin had no stimulatory effect under these conditions.ConclusionSerotonin may have a physiological role in the corpus hemorrhagicum, when luteinization is initiated.