Specific gonadotrophin-releasing hormone analogue binding predominantly in human luteinized follicular aspirates and not in human pre-ovulatory follicles

In an attempt to resolve the apparent controversy in the observed effects of gonadotrophin-releasing hormone (GnRH) analogues on the ovary, conventional binding studies were conducted with a GnRH agonist and an antagonist in various ovarian tissues to demonstrate possible GnRH receptor binding. In human luteinized granulosa cells derived from unstimulated in-vitro fertilization cycles, high affinity receptor binding was present in 17 out of 24 patients, while binding was not observed in any of the six pre-ovulatory follicles removed during abdominal surgery. Apparently contradictory observations on the direct ovarian effects of GnRH analogues may be the result of the intermittent presence of high affinity GnRH receptors. Our observations indicate that in the human, high affinity ovarian GnRH receptors are present predominantly in ovarian tissue after the luteinizing hormone surge. We also propose the possibility of regulation and activation of a human follicular GnRH receptor in the ovary as a physiological process which may be influenced pharmacologically.