title: Coincidence of down-regulation and desensitization in pituitary gonadotrophs stimulated by gonadotropin releasing hormone.
abstract: The dynamics of gonadotropin releasing hormone (GnRH) induced luteinizing hormone (LH) release was studied in vitro by superfusion of cultured pituitary cells. Continuous exposure of the cells to GnRH resulted in desensitization of the gonadotroph responsiveness to further stimulation by the hormone. The refractory state was achieved within 4 hr of hormone introduction (10(-7) M) and was accompanied by down-regulation of GnRH receptors (50%) assayed by equilibration with [125I]iodo-[D-Ala6]des-Gly10-GnRH N-ethylamide. The data indicate that GnRH can regulate the number of its own receptors, and that desensitization is accompanied by down-regulation.
mesh_terms: D000818:Animals; D004351:Drug Resistance; D005260:Female; D066298:In Vitro Techniques; D007986:Luteinizing Hormone / Q000378:metabolism*; D010902:Pituitary Gland / Q000187:drug effects* / Q000378:metabolism; D010906:Pituitary Hormone-Releasing Hormones / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism; D011966:Receptors, LHRH; D013997:Time Factors
chemical_list: D010906:Pituitary Hormone-Releasing Hormones; D011956:Receptors, Cell Surface; D011966:Receptors, LHRH; D007986:Luteinizing Hormone