title: Pharmacodynamics of gonadotropin-releasing hormone (GnRH). II. Pattern of GnRH delivery alters pituitary luteinizing hormone secretion in women.
abstract: The pulse frequency, amplitude, and mode of administration of GnRH all influence gonadotropin secretion and, ultimately, pituitary-gonadal function. We studied plasma LH responses to repetitive iv administration of GnRH given hourly for 5 h as a 2-microgram rapid (less than 15 s) bolus dose or a 2-microgram dose infused for 15 min of each hour in seven women deficient in endogenous GnRH and sex steroids. Plasma LH levels, measured at 10-min intervals throughout the 5-h period, rose more briskly (pattern X time course interactions: F = 3.33; P less than 0.0001) to higher levels overall (F = 11.7; P = 0.014) after rapid bolus GnRH administration than after GnRH infusion. Plasma FSH levels increased during both modes of delivery, with higher responses to rapid bolus GnRH administration (P = 0.005). Plasma estradiol levels did not change during either 5-h study. We conclude that the pattern of delivery of GnRH is a determinant of pituitary LH and FSH secretion in untreated hypogonadotropic women, and therefore, that alterations in the GnRH wave form and/or peak plasma GnRH concentrations consequent upon different rates of GnRH entry into the blood-stream may explain the different responses that occur when GnRH is given by different routes.
mesh_terms: D000328:Adult; D000568:Amenorrhea / Q000097:blood; D004341:Drug Evaluation; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007027:Hypothalamic Diseases / Q000097:blood; D007262:Infusions, Intravenous; D007275:Injections, Intravenous; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism; D010906:Pituitary Hormone-Releasing Hormones / Q000008:administration & dosage / Q000494:pharmacology*; D011897:Random Allocation; D013997:Time Factors
chemical_list: D010906:Pituitary Hormone-Releasing Hormones; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone