title: Ghrelin suppresses secretion of luteinizing hormone in humans.
abstract: BACKGROUND
  Ghrelin affects the hypothalamic-pituitary-gonadal axis in various nonhuman mammalians, predominantly by suppressing secretion of LH. However, for humans, no such evidence exists.
  
  
  OBJECTIVE
  Our objective was to study the effect of ghrelin on secretion of LH and testosterone in humans.
  
  
  METHODS
  Nocturnal (2000-0700 h) secretion profiles of LH and testosterone were determined in 10 healthy males (25.7 +/- 3.0 yr) twice, receiving 50 microg ghrelin or placebo at 2200, 2300, 2400, and 0100 h, in this single-blind, randomized, cross-over study.
  
  
  RESULTS
  Ghrelin was associated with significantly (P < 0.05) lower mean plasma levels of both LH (2340-0200 h) and testosterone (0040-0300 h) than placebo. LH peak levels of the pulse after first administration of ghrelin/placebo were significantly (P = 0.014) smaller in the ghrelin (2.98 +/- 1.34 mIU/ml) than in the placebo condition (4.37 +/- 1.09 mIU/ml). In addition, the interval between this and the preceding peak was significantly (P = 0.010) longer in the ghrelin (255.8 +/- 79.1 min) than in the placebo condition (190.8 +/- 51.0 min). Significantly (P = 0.005) more LH pulses occurred with placebo (3.2 +/- 0.75) than ghrelin (2.6 +/- 0.7) subsequent to ghrelin/placebo administration.
  
  
  CONCLUSIONS
  Ghrelin caused both a delay and suppression of the amplitude of LH pulses. These findings are in accordance with those in nonhuman mammalians.
authors.affiliation: Max-Planck Institute of Psychiatry, Kraepelinstrasse 2-10, 80804 Munich, Germany. kluge@mpipsykl.mpg.de
authors.forename: Michael
authors.initials: M
authors.lastname: Kluge
authors.forename: Petra
authors.initials: P
authors.lastname: Schüssler
authors.forename: Manfred
authors.initials: M
authors.lastname: Uhr
authors.forename: Alexander
authors.initials: A
authors.lastname: Yassouridis
authors.forename: Axel
authors.initials: A
authors.lastname: Steiger
mesh_terms: D000328:Adult; D019540:Area Under Curve; D018592:Cross-Over Studies; D054439:Ghrelin; D006801:Humans; D007986:Luteinizing Hormone / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008297:Male; D036361:Peptide Hormones / Q000494:pharmacology*; D016037:Single-Blind Method; D013739:Testosterone / Q000097:blood
chemical_list: D054439:Ghrelin; D036361:Peptide Hormones; D013739:Testosterone; D007986:Luteinizing Hormone