title: Expression of the GABAB receptor in Xenopus oocytes and inhibition of the response by activation of protein kinase C.
abstract: The functional GABAB receptor was expressed in Xenopus oocytes by injecting mRNA obtained from the cerebellum of the rat. Application of GABA in the presence of bicuculline induced a hyperpolarization under current-clamp conditions and an outward current under voltage-clamp conditions. Baclofen mimicked the effect of GABA in the presence of bicuculline, and the effect of baclofen was antagonized by phaclofen. The GABA-induced outward current was slightly inhibited by treatment with GDP-beta-S and was completely inhibited by treatment with GTP-gamma-S. The activation of protein kinase C by 12-O-tetradecanoylphorbol-13-acetate (TPA), but not 4 alpha-phorbol-12,13-didecanoate, suppressed the GABAB receptor-mediated hyperpolarization, and the effect of TPA was antagonized by sphingosine. Thus, activation of protein kinase C inhibits the expressed GABAB receptor-mediated response.
authors.affiliation: Department of Pharmacology, Kobe University School of Medicine, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Taniyama
authors.forename: K
authors.initials: K
authors.lastname: Takeda
authors.forename: H
authors.initials: H
authors.lastname: Ando
authors.forename: T
authors.initials: T
authors.lastname: Kuno
authors.forename: C
authors.initials: C
authors.lastname: Tanaka
mesh_terms: D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D008845:Microinjections; D009865:Oocytes; D010703:Phorbol Esters / Q000494:pharmacology; D011493:Protein Kinase C / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011963:Receptors, GABA-A / Q000502:physiology*; D011994:Recombinant Proteins / Q000502:physiology; D015398:Signal Transduction; D013110:Sphingosine / Q000494:pharmacology; D014982:Xenopus laevis
chemical_list: D010703:Phorbol Esters; D012333:RNA, Messenger; D011963:Receptors, GABA-A; D011994:Recombinant Proteins; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D011493:Protein Kinase C; D019204:GTP-Binding Proteins; D013110:Sphingosine; D001640:Bicuculline