Expression of the GABAB receptor in Xenopus oocytes and inhibition of the response by activation of protein kinase C

• Published in: FEBS letters 1991-01, Vol.278 (2), p.222-224
• Main Authors: Taniyama, Kohtaro, Takeda, Koichiro, Ando, Hiroshi, Kuno, Takayosi, Tanaka, Chikako
• Format: Article
• Language: English
• Subjects: Aminoacid receptors (glycine, glutamate, gaba); Animals; Bicuculline - pharmacology; Biological and medical sciences; Cell receptors; Cell structures and functions; Fundamental and applied biological sciences. Psychology; GABAB receptor; GTP-Binding Proteins - physiology; Guanosine 5'-O-(3-Thiotriphosphate) - pharmacology; Membrane Potentials - drug effects; Microinjections; Molecular and cellular biology; mRNA injected oocyte; Oocytes; Phorbol Esters - pharmacology; Protein kinase C; Protein Kinase C - physiology; Rats; Receptors, GABA-A - physiology; Recombinant Proteins - physiology; RNA, Messenger - genetics; Signal Transduction; Sphingosine - pharmacology; Xenopus laevis
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(91)80121-I

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‐β‐S and was completely inhibited by treatment with GTP‐γ‐S. The activation of protein kinase C by 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA), but not 4α‐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.