title: DS1, a delta subunit-containing GABA(A) receptor agonist, increases gonadotropin subunit gene expression in mouse pituitary gonadotrophs.
abstract: 4-Chloro-N-[6,8-dibromo-2-(2-thienyl)imidazo[1,2-alpyridine-3-yl] (DS1) is a GABA(A) receptor agonist that selectively binds to delta subunit-containing GABA(A) alpha4beta3delta receptors. In the present study, we examined the effect of DS1 on pituitary gonadotropin subunit gene expression using the mouse pituitary gonadotroph cell line LbetaT2. DS1 increased the promoter activity of the gonadotropin subunits luteinizing hormone beta (LHbeta), follicle-stimulating hormone beta (FSHbeta), and alpha. Gonadotropin-releasing hormone (GnRH) receptor promoters were also activated by DS1. The effects of DS1 on gonadotropin subunit promoters were obvious, but they were less than those induced by stimulation with GnRH. GnRH-stimulated gonadotropin subunit promoters were enhanced in the presence of DS1. A prototypic specific agonist for GABAA receptors, muscimol, failed to increase LHbeta and FSHbeta subunit promoter activity and had no effect on GnRH-increased LHbeta and FSHbeta promoter activity. In addition, SKF97541, a specific agonist for GABAB receptors, did not modulate basal or GnRH-induced LHbeta and FSHbeta promoter activity. A natural GABA compound failed to increase gonadotropin promoter activity and potentiated the effect of GnRH on the FSHbeta promoter. DS1 increased the activity of serum response element (SRE) and cAMP response element (CRE) promoters, which reflect the activity of the extracellular signal-regulated kinase and cAMP/protein kinase A (PKA) pathways, and GnRH-increased SRE and CRE promoter activity was enhanced in the presence of DS1. A specific inhibitor of the ERK signaling pathway, U0126, prevented DS1-induced LHbeta and FSHbeta promoter activity almost completely; however, H89, a PKA inhibitor, did not modulate the effect of DS1. Our current observations demonstrate that the GABAA alpha4beta3delta receptor agonist DS1 can stimulate gonadotropin subunit gene expression in association with the ERK signaling pathway.
authors.affiliation: Department of Obstetrics and Gynecology, Shimane University School of Medicine, Izumo, Japan.
authors.forename: Tselmeg
authors.initials: T
authors.lastname: Mijiddorj
authors.affiliation: Department of Obstetrics and Gynecology, Shimane University School of Medicine, Izumo, Japan kanasaki@med.shimane-u.ac.jp.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Kanasaki
authors.affiliation: Department of Obstetrics and Gynecology, Shimane University School of Medicine, Izumo, Japan.
authors.forename: Unurjargal
authors.initials: U
authors.lastname: Sukhbaatar
authors.affiliation: Department of Obstetrics and Gynecology, Shimane University School of Medicine, Izumo, Japan.
authors.forename: Aki
authors.initials: A
authors.lastname: Oride
authors.affiliation: Department of Obstetrics and Gynecology, Shimane University School of Medicine, Izumo, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Kyo
mesh_terms: D000818:Animals; D002460:Cell Line; D005640:Follicle Stimulating Hormone / Q000235:genetics* / Q000378:metabolism; D018755:GABA Agonists / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects*; D052681:Gonadotrophs / Q000187:drug effects* / Q000378:metabolism; D037101:Luteinizing Hormone, beta Subunit / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D009118:Muscimol / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D021122:Protein Subunits / Q000378:metabolism; D011963:Receptors, GABA-A / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D018755:GABA Agonists; D037101:Luteinizing Hormone, beta Subunit; D021122:Protein Subunits; D011963:Receptors, GABA-A; D009118:Muscimol; D005640:Follicle Stimulating Hormone
keywords: follicle-stimulating hormone (FSH/FSH receptor); gonadotropin-releasing hormone (GnRH/GnRH receptor); luteinizing hormone (LH/LH receptor); neuroendocrinology