GnRH- and cAMP-Stimulated Human Chorionic Gonadotropin Secretion from Perifused Placental Cells

Abstract

Gonadotropin releasing hormone (GnRH) stimulates human chorionic gonadotropin (hCG) secretion in a specific, dose-dependent manner in vitro (1–8). GnRH in maternal circulation and stimulating hCG secretion may be primarily of placental origin; GnRH synthesized and secreted by cytotrophoblast stimulates hCG synthesis and secretion by syncytio-trophoblast (1, 3, 7–13). A component of basal hCG secretion may be GnRH independent (9). Cultured placental tissue obtained throughout gestation responds to GnRH, but may be most responsive at about 10 weeks (13–15). Prior to obtaining data presented, repeated attempts were made to demonstrate GnRH-stimulated hCG secretion from perifused placental cells. Initially, trophoblast dissected from placenta in buffer or culture media on ice were dissociated with collagenase (lh, 37°C). Hematocytes were removed and cells plated as detailed below. Cell viability was limited ( 10-mIU/mL media/h), and cells responded to 24-h GnRH (10–9 M) exposure in static culture, but not to 5-min GnRH pulses (10–9 M) in perifusion. Subsequently, enzyme-free physical dissociation at 21°C has continuously provided cultures of greater viability (>90%) and allowed hCG secretion in response to GnRH pulses in perifusion.