Suppression of corpus luteum function by the gonadotropin-releasing hormone antagonist Nal-Glu: effect of the dose and timing of human chorionic gonadotropin administration.
Academic Article
Overview
abstract
OBJECTIVE: To assess the effect of gonadotropin-releasing hormone antagonist Nal-Glu administration in the luteal phase and the potential rescue by exogenous human chorionic gonadotropin (hCG) of corpus luteum (CL) after antagonist treatment. DESIGN: We studied the dose of Nal-Glu required for luteolysis and subsequently we coadministered low doses of hCG for 3 consecutive days either simultaneously to Nal-Glu administration (n = 5), or 48 (n = 5), or 72 hours (n = 5) later. Six additional participants received pharmacological doses of hCG 48 hours after the luteolytic dose of Nal-Glu. SETTING: Participants were studied in Clinique Endocrinologique, Nantes, and in Service d'Endocrinologie, Hôpital Bicêtre, Le Kremlin Bicetre, France. PARTICIPANTS: Twenty-nine normal young women (ages 20 to 35) were studied. INTERVENTIONS: None. MAIN OUTCOME MEASURE: Measurements of follicle-stimulating hormone, luteinizing hormone (LH), estradiol, Progesterone (P) levels were performed by radioimmunoassay before, during, and after the various treatment regimens. RESULTS: Complete luteolysis occurred in women who received 10 mg of Nal-Glu daily on days 4 and 5 after the LH surge. The coadministration of Nal-Glu and hCG overrode the effect of the antagonist (P = 48.8 +/- 22.5 versus 60.8 +/- 3.1 nmol/L in controls treated with hCG alone [NS]). When hCG treatment was started 48 hours after Nal-Glu, a partial luteolysis occurred (P = 33.8 +/- 10.9 versus 117 +/- 12.9 nmol/L, P less than 0.01). When hCG was started 72 hours after Nal-Glu, a complete luteolysis occurred (P = 5.8 +/- 2.05 versus 36.2 +/- 0.6 nmol/L, P less than 0.01). Higher doses of hCG (1,500 or 5,000 IU) administered 72 hours after Nal-Glu resulted in a significant rescue of CL function (P = 37.7 +/- 4.8 and P = 43.8 +/- 22.2 versus 74.5 +/- 19.8 and 130.2 +/- 14.3 nmol/L, P less than 0.05), respectively. CONCLUSIONS: These results confirm the LH dependence of CL function. The suppression of CL LH support for 72 hours induced a compromise of the CL nonreversible by low doses of hCG mimicking early pregnancy but reversible with pharmacological doses.
