title: A powerful GABA(B) receptor-mediated inhibition of GABAergic neurons in arcuate nucleus.
abstract: We combined histofluorescence with in situ hybridization to identify GABAergic neurons in the arcuate nucleus (ARC) following electrophysiological recording, using GAD65 as a marker. Intracellular recordings 91 were made in hypothalamic slices prepared from ovariectomized guinea pigs. Over 90% of ARC neurons tested with the GABA(B) receptor agonist baclofen responded with a membrane hyperpolarization or an outward current. The hyperpolarization was dose dependent, and the GABA(B) receptor antagonist CGP 35,348 produced a rightward shift in the agonist dose-response curve. Agonist potency was lower, and the efficacy greater, in GAD-positive neurons. The use of this novel technique for identifying GABAergic neurons thus reveals differences in the pharmacodynamics of GABA(B) receptor activation between GABAergic and non-GABAergic ARC neurons.
authors.affiliation: Department of Physiology and Pharmacology, L334 Oregon Health Sciences University, Portland 97201, USA.
authors.forename: E J
authors.initials: EJ
authors.lastname: Wagner
authors.forename: M A
authors.initials: MA
authors.lastname: Bosch
authors.forename: M J
authors.initials: MJ
authors.lastname: Kelly
authors.forename: O K
authors.initials: OK
authors.lastname: Rønnekleiv
mesh_terms: D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000166:cytology / Q000502:physiology*; D001418:Baclofen / Q000494:pharmacology; D005260:Female; D005455:Fluorescent Antibody Technique; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D005968:Glutamate Decarboxylase / Q000032:analysis; D006168:Guinea Pigs; D017403:In Situ Hybridization; D066298:In Vitro Techniques; D009433:Neural Inhibition; D009474:Neurons / Q000502:physiology*; D009943:Organophosphorus Compounds / Q000494:pharmacology; D018080:Receptors, GABA-B / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
chemical_list: D018755:GABA Agonists; D018756:GABA Antagonists; D009943:Organophosphorus Compounds; D018080:Receptors, GABA-B; D005680:gamma-Aminobutyric Acid; C066430:CGP 35348; D005968:Glutamate Decarboxylase; D001418:Baclofen