title: Effects of GABA(A) receptor modulation on the expression of GnRH gene and GnRH receptor (GnRH-R) gene in the hypothalamus and GnRH-R gene in the anterior pituitary gland of follicular-phase ewes.
abstract: The effect of prolonged, intermittent infusion of GABA(A) receptor agonist (muscimol) or GABA(A) receptor antagonist (bicuculline) into the third cerebral ventricle on the expression of GnRH gene and GnRH-R gene in the hypothalamus and GnRH-R gene in the anterior pituitary gland was examined in follicular-phase ewes by real-time PCR. The activation or inhibition of GABA(A) receptors in the hypothalamus decreased or increased the expression of GnRH and GnRH-R genes and LH secretion, respectively. The present results indicate that the GABAergic system in the hypothalamus of follicular-phase ewes may suppress, via hypothalamic GABA(A) receptors, the expression of GnRH and GnRH-R genes in this structure. The decrease or increase of GnRH-R mRNA in the anterior pituitary gland and LH secretion in the muscimol- or bicuculline-treated ewes, respectively, is probably a consequence of parallel changes in the release of GnRH from the hypothalamus activating GnRH-R gene expression. It is suggested that GABA acting through the GABA(A) receptor mechanism on the expression of GnRH gene and GnRH-R gene in the hypothalamus may be involved in two processes: the biosynthesis of GnRH and the release of this neurohormone in the hypothalamus.
authors.affiliation: The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Warsaw, Poland. m.ciechanowska@ifzz.pan.pl
authors.forename: Magdalena
authors.initials: M
authors.lastname: Ciechanowska
authors.forename: Magdalena
authors.initials: M
authors.lastname: Lapot
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Malewski
authors.forename: Krystyna
authors.initials: K
authors.lastname: Mateusiak
authors.forename: Tomasz
authors.initials: T
authors.lastname: Misztal
authors.forename: Franciszek
authors.initials: F
authors.lastname: Przekop
mesh_terms: D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D005260:Female; D005498:Follicular Phase / Q000187:drug effects / Q000235:genetics*; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D007987:Gonadotropin-Releasing Hormone / Q000096:biosynthesis* / Q000235:genetics; D007031:Hypothalamus / Q000187:drug effects / Q000502:physiology*; D007986:Luteinizing Hormone / Q000097:blood / Q000502:physiology; D009118:Muscimol / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011897:Random Allocation; D011963:Receptors, GABA-A / Q000235:genetics / Q000378:metabolism*; D011966:Receptors, LHRH / Q000096:biosynthesis* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D012756:Sheep / Q000235:genetics* / Q000378:metabolism; D018709:Statistics, Nonparametric
chemical_list: D018755:GABA Agonists; D018756:GABA Antagonists; D012333:RNA, Messenger; D011963:Receptors, GABA-A; D011966:Receptors, LHRH; D009118:Muscimol; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D001640:Bicuculline