title: Gonadal steroids and opioid control of gonadotropin secretion in man.
abstract: The aim of this study was to ascertain whether there was an interrelationship between gonadal steroids and endogenous opioid peptides. The effects of naloxone (20 mg, intravenously) and of a met-enkephalin analog (DAMME) (250 micrograms, intravenously) on gonadotropin secretion in three castrated men (18 to 23 years of age) and in five age-matched normal men were studied. Normal subjects were studied before and after treatment with a specific nonsteroidal estrogen receptor antagonist, clomiphene. Naloxone caused a significant increase in luteinizing hormone (LH) (P less than 0.05); in these subjects, clomiphene treatment significantly increased LH and follicle-stimulating hormone plasma levels but totally suppressed the naloxone-induced rise in LH. In castrated men, naloxone failed to increase plasma LH levels. However, DAMME significantly reduced plasma LH levels in normal, in castrated, and in clomiphene-treated normal subjects. The results demonstrate that in castrated subjects who lack gonadal steroids and in normal subjects with blocked estrogen receptors there is a reduced opioid inhibitory tone on gonadotropin secretion. The effect of DAMME on gonadotropin secretion, however, is not influenced by the gonadal steroid environment.
mesh_terms: D000293:Adolescent; D000328:Adult; D002369:Castration; D002996:Clomiphene / Q000494:pharmacology; D005405:D-Ala(2),MePhe(4),Met(0)-ol-enkephalin / Q000494:pharmacology*; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D006801:Humans; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D011957:Receptors, Opioid / Q000502:physiology*
chemical_list: D011957:Receptors, Opioid; D002996:Clomiphene; D009270:Naloxone; D005405:D-Ala(2),MePhe(4),Met(0)-ol-enkephalin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone