INFLUENCE OF SEROTONIN ON PROGESTERONE AND ESTRADIOL SECRETION OF CULTURED HUMAN GRANULOSA-CELLS

Objective: To explore the direct action of serotonin on progesterone (P) and estradiol (E2) secretion of human granulosa cells cultured in serum-free medium. Design: Progesterone 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. Setting: In vitro fertilization and embryo transfer (IVF-ET) for infertility treatment at the University Women's Hospital, University of Tubingen, Germany. Patients, Participants: Fourteen women, 30 +/- 3 years old, undergoing IVF-ET. Results: Serotonin 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. Conclusion: Serotonin may have a physiological role in the corpus hemorrhagicum, when luteinization is initiated.