title: Activation of GABA B receptors in the anterior pituitary inhibits prolactin and luteinizing hormone secretion.
abstract: Previous work from our laboratory showed that baclofen could lower serum prolactin (PRL) levels acting at the central nervous system. The present experiments were designed to evaluate whether the gamma-aminobutyric acid B agonist was also effective in inhibiting hormone release at the pituitary level. In monolayer cultures of adenohypophyseal dispersed cells, baclofen inhibited basal PRL secretion after 1 or 2 h of incubation. This inhibition was significantly abolished by three antagonists: phaclofen, 3-aminopropyl-phosphonic acid and 4-aminobutylphosphonic acid. Furthermore, baclofen inhibited the thyrotropin-releasing hormone-induced PRL release in a concentration-dependent manner. With regard to gonadotropin secretion, baclofen was unable to modify basal luteinizing hormone (LH) secretion, but significantly inhibited the LH-releasing hormone-induced LH release. These results show that baclofen, in addition to its central neuroendocrine effects, inhibits pituitary hormone secretion, under basal and/or stimulated conditions, by direct action at the pituitary level.
authors.affiliation: Instituto de Biologia y Medicina Experimental, Buenos Aires, Argentina.
authors.forename: V
authors.initials: V
authors.lastname: Lux-Lantos
authors.forename: E
authors.initials: E
authors.lastname: Rey
authors.forename: C
authors.initials: C
authors.lastname: Libertun
mesh_terms: D000818:Animals; D001418:Baclofen / Q000031:analogs & derivatives / Q000494:pharmacology; D002082:Butylamines / Q000494:pharmacology; D002478:Cells, Cultured; D005260:Female; D018756:GABA Antagonists; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007774:Lactation / Q000502:physiology; D007986:Luteinizing Hormone / Q000378:metabolism*; D009943:Organophosphorus Compounds / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000502:physiology*; D011359:Proestrus / Q000502:physiology; D011388:Prolactin / Q000378:metabolism*; D011437:Propylamines / Q000494:pharmacology; D051381:Rats; D011963:Receptors, GABA-A / Q000187:drug effects / Q000502:physiology*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology
chemical_list: D002082:Butylamines; D018756:GABA Antagonists; D009943:Organophosphorus Compounds; D011437:Propylamines; D011963:Receptors, GABA-A; C052329:phaclofen; D007987:Gonadotropin-Releasing Hormone; C079360:4-aminobutylphosphonic acid; D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D007986:Luteinizing Hormone; D001418:Baclofen; C011649:3-aminopropylphosphonic acid