title: Involvement of H1 histamine receptor in basal and estrogen-stimulated luteinizing hormone-releasing hormone secretion in rats in vitro.
abstract: For determination of the roles of histamine and its receptors, H1 and H2, in the control of basal and estrogen-induced LH-RH secretion, the mediobasal hypothalamus (MBH) and/or pituitary was excised from normally cycling female rats and perifused in an in vitro sequential double chamber perifusion system. Administration of 10(-7) M histamine caused significant release (90-170% increase, p less than 0.05) of LH from the pituitary in sequence with the MBH, whereas 10(-7) M histamine had no effect on LH release from the pituitary perifused alone; administration of 10(-5) M 2-methylhistamine, an H1 agonist, induced significant release (50-120% increase, p less than 0.05) of LH-RH from the MBH, and addition of 10(-5) M mepyramine, and H1 antagonist, abolished this LH-RH release. The LH concentrations in the efflux were not affected by the administration of the H2 agonist 4-methylhistamine. Estradiol caused significant release of LH-RH from the MBH and LH from the pituitary in sequence with the MBH. The estradiol-induced release of LH-RH and LH were completely abolished by perifusion with medium containing 10(-5) M mepyramine. The H2 receptor antagonist ranitidine did not affect estradiol-induced LH release. Histamine did not change the LH release induced by 20 ng LH-RH. These findings suggest that histamine induces release of hypothalamic LH-RH, and that histamine H1 receptors in the hypothalamus are involved in the basal and estradiol-induced LH-RH release.
mesh_terms: D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism*; D007033:Hypothalamus, Middle / Q000378:metabolism; D007986:Luteinizing Hormone / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011968:Receptors, Histamine / Q000502:physiology*; D011969:Receptors, Histamine H1 / Q000502:physiology; D011970:Receptors, Histamine H2 / Q000502:physiology
chemical_list: D011968:Receptors, Histamine; D011969:Receptors, Histamine H1; D011970:Receptors, Histamine H2; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D007986:Luteinizing Hormone