Synaptic  5 Subunit-Containing GABAA Receptors Mediate IPSPs Elicited by Dendrite-Preferring Cells in Rat Neocortex

Ali, A.B. and Thomson, A.M. (2008) Synaptic  5 Subunit-Containing GABAA Receptors Mediate IPSPs Elicited by Dendrite-Preferring Cells in Rat Neocortex. Cerebral Cortex, 18 (6). p. 1260. 10.1093/cercor/bhm160.

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DOI: 10.1093/cercor/bhm160

Abstract

Previous studies indicated that one class of dendrite-preferring hippocampal interneurones inhibits pyramidal cells via a5 gaminobutyric acid (GABAA) receptors whereas parvalbumin- and CCK-containing basket cells act via a1 and a2/3 GABAA receptors, respectively. This study asked whether there is selective insertion of different a subunit--containing GABAA receptors at neocortical inhibitory synapses innervated by specific classes of interneurones. The benzodiazepine site pharmacology of inhibitory postsynaptic potentials (IPSPs) elicited in neocortical pyramidal cells by 3 classes of interneurones was explored with dual whole-cell recordings in neocortical slices from juvenile rats (P18--23). Fast IPSPs activated by multipolar interneurones with narrow spikes and nonadapting firing patterns were powerfully enhanced by the a1-preferring agonist zolpidem, suggesting mediation via larger proportion of a1 GABAA receptors than those activated by multipolar, adapting interneurones, which were less strongly enhanced by zolpidem, but equally insensitive to the a5-selective inverse agonist IAalpha5 (MSD, Essex, UK) suggesting mediation predominantly via a2/3 GABAA receptors. In contrast, the IPSPs elicited by bitufted, dendrite-preferring interneurones were reduced by IAalpha5 and by zinc and insensitive to zolpidem despite enhancement by the broad-spectrum agonist, diazepam. Thus insertion of GABAA receptors at synapses on neocortical pyramids is input-specific, with proximal inhibition employing a1 and a2/3 GABAA receptors and dendrite-preferring bitufted interneurones activating a5 GABAA receptors.

Item Type:Article
Uncontrolled Keywords:benzodiazepine site, GABAA, interneuron, IPSPs, neocortex, synaptic Introduction
Departments, units and centres:Department of Pharmacology > Department of Pharmacology
ID Code:2638
Journal or Publication Title:Cerebral Cortex
Deposited By:Library Staff
Deposited On:12 Jan 2012 17:18
Last Modified:09 Feb 2012 17:36

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