Studies on the effect of gonadotropin-releasing hormone and its agonist on human luteal steroidogenesis in vitro.

The possible direct effect of gonadotropin-releasing hormone (GnRH) and a potent GnRH agonist [( imBzl )-D- His6 -Pro9-NEt]-GnRH on basal and human chorionic gonadotropin (hCG)-stimulated progesterone, androstenedione, and estradiol production by cultured human luteal cells was examined. Luteal cells from the early or midluteal phase of the menstrual cycle responded to hCG stimulation with two to fivefold increases in steroid production in both short-term (4 hours) and long-term (up to 144 hours) culture in chemically defined medium without serum. After 48 hours in this system, levels of androstenedione and estradiol were very low, and progesterone was the predominant steroid produced. The addition of GnRH or a potent GnRH agonist to the medium had no effect on either basal or hCG-stimulated steroid secretion. When luteal cells were cultured longer (for up to 10 days) in the presence of serum, GnRH agonist caused no significant alteration of either basal or hCG-stimulated progesterone production. Collectively, these results support the conclusion that GnRH and its potent agonist do not act directly on human corpora luteal cells to modulate steroidogenesis.