NeropharmacologyA powerful GABAB receptΦ-mediated inhibition of GABAergic neurons in the arcuate nucleusWagner, Edward J.1,3; Bosch, Martha A.1; Kelly, Martin J.1; Rønnekleiv, K1,2Author Information 1Department of Physiology and Pharmacology, L334, Oregon Health Sciences University, 3181 SW Sam Jackson Park Road, Portland, OR 97201 2Division of Neuroscience, Oregon Regional Private Research Centre, Beaverton, OR 97005, USA 3Corresponding Author: Edward J. Wagner ACKNOWLEDGEMENTS: The technical assistance of Mr Barry R. Naylor is grateful acknowledged. The experiments described in this study were supported by PHS Grants NS 35944, DA 05158, DA 00192 (RSDA to Martin J. Kelly) and HD-18185 (Population P30 Program Project Grant). Received 9 September 1998; accepted 16 October 1998 NeuroReport: December 21st, 1998 - Volume 9 - Issue 18 - p 4171-4177 Buy Abstract WE combined histofluorescence with in sit u hybridization to identify GABAergic neurons in the arcuate nucleus (ARC) following electrophysiological recordings, using GAD65 as a marker. Intracellular recordings were made in hypothalamic slices prepared from ovariectomized guinea pigs. Over 90% of ARC neurons tested with the GABAB receptor agonist baclofen responded with a membrane hyperpolarization or an outward current. The hyperpolarization was dose-dependent, and the GABAB 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 GABAB receptor activation GABAergic and non-GABAergic ARC neurons © 1998 Lippincott Williams & Wilkins, Inc.