title: Pharmacological characteristics of GABAA responses in postnatal suprachiasmatic neurons in culture.
abstract: The suprachiasmatic nucleus (SCN) is considered to be an endogenous circadian pacemaker. Previous studies have suggested functional roles of gamma-aminobutyric acid (GABA) in the control of circadian rhythms. In this study, the responses to applied GABA in cultured SCN neurons dissociated from postnatal rat hypothalamus were investigated using whole-cell voltage-clamp techniques. GABA and muscimol induced a large current response (EC50 values 5.3 and 1.6 microM, respectively), which was blocked by the GABAA antagonist bicuculline. This current response was also blocked by Zn2+ (0.5-50 microM) in a concentration-dependent manner, but was not potentiated by diazepam (10 microM) or ethanol (21 mM). These characteristics seem to correspond to those of GABAA receptors that lack gamma-type subunits.
authors.affiliation: Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
authors.forename: F
authors.initials: F
authors.lastname: Kawahara
authors.forename: H
authors.initials: H
authors.lastname: Saito
authors.forename: H
authors.initials: H
authors.lastname: Katsuki
mesh_terms: D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D002478:Cells, Cultured; D004594:Electrophysiology; D058787:GABA-A Receptor Antagonists; D008564:Membrane Potentials / Q000187:drug effects; D009118:Muscimol / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects*; D051381:Rats; D011963:Receptors, GABA-A / Q000187:drug effects*; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015032:Zinc / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D058787:GABA-A Receptor Antagonists; D011963:Receptors, GABA-A; D009118:Muscimol; D005680:gamma-Aminobutyric Acid; D015032:Zinc; D001640:Bicuculline