title: Evaluation of the impact of concurrent gonadotropin-releasing hormone (GnRH) antagonist administration on GnRH agonist-induced gonadotrope desensitization.
abstract: OBJECTIVE
  To evaluate the impact of chronic GnRH antagonist therapy on the extent of GnRH agonist-induced gonadotrope desensitization.
  
  
  METHODS
  Prospective and controlled.
  
  
  METHODS
  Primate Research Center.
  
  
  METHODS
  Six reproductive age cycling female baboons (Papio cyanocephalus anubis).
  
  
  METHODS
  The animals were divided into two groups. Group A received a total of 19 pulses of 0.83 microgram/kg leuprolide acetate (LA) on a 12-hour dosing schedule. Group B received Nal-Lys (3 mg/kg then 1 mg/kg every other day) for 1 week and then added an identical 19 pulses of LA while continuing Nal-Lys therapy.
  
  
  METHODS
  Characterization of the gonadotropin response was done by collecting serum samples at -15, 0, 15, 30, 60, 90, 120, 240, and 480 minutes relative to the injection of the LA.
  
  
  RESULTS
  After equivalent baseline responses, the baboons pretreated with Na-Lys had an increased LH and FSH response to the administration of the LA. After a total of 19 pulses of the LA, the Nal-Lys-treated animals had an increased FSH response in comparison to the untreated controls. This indicates that the extent of gonadotrope desensitization was reduced in the presence of the GnRH antagonist.
  
  
  CONCLUSIONS
  The presence of GnRH antagonist reduces the extent of gonadotrope desensitization in response to the administration of repetitive pulses of GnRH agonist.
authors.affiliation: Department of Obstetrics and Gynecology, Wilford Hall Medical Center, Valhalla, New York, USA.
authors.forename: E H
authors.initials: EH
authors.lastname: Illions
authors.forename: R T
authors.initials: RT
authors.lastname: Scott
authors.forename: K D
authors.initials: KD
authors.lastname: Carey
authors.forename: D
authors.initials: D
authors.lastname: Navot
mesh_terms: D000818:Animals; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood*; D007987:Gonadotropin-Releasing Hormone / Q000819:agonists* / Q000037:antagonists & inhibitors*; D016729:Leuprolide / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000097:blood*; D009842:Oligopeptides / Q000494:pharmacology*; D010215:Papio; D011446:Prospective Studies; D012016:Reference Values
chemical_list: D009842:Oligopeptides; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; C057022:iturelix; D016729:Leuprolide