Journal article
Hippocampal Network Hyperactivity After Selective Reduction of Tonic Inhibition in GABAA Receptor α5 Subunit–Deficient Mice
Journal of neurophysiology, Vol.95(5), pp.2796-2807
05/2006
DOI: 10.1152/jn.01122.2005
PMID: 16452257
Abstract
Functionally, γ-aminobutyric acid receptor (GABAR)–mediated inhibition can be classified as phasic (synaptic) and tonic (extrasynaptic). The GABARs underlying tonic inhibition assemble from subunits different from those responsible for phasic inhibition. We wanted to assess the excitability of hippocampal pyramidal cell (PC) networks following a selective impairment of tonic inhibition. This is difficult to accomplish by pharmacological means. Because the GABAR α5 subunits mostly mediate the tonic inhibition in CA1 and CA3 PCs, we quantified changes in tonic inhibition and examined network excitability in slices of adult gabra5−/− mice. In gabra5−/− CA1 and CA3 PCs tonic inhibitory currents were 60 and 53%, respectively, of those recorded in wild type (WT), with no alterations in phasic inhibition. The amount of tonic inhibition recorded in slices was significantly affected by the method of slice storage (interface or submerged chamber). Field recordings in gabra5−/− CA3 pyramidal layer showed an increased network excitability that was decreased by the GABAR agonist muscimol at a concentration that restored the tonic inhibition of gabra5−/− PCs to the WT level without altering phasic inhibition. Through a battery of pharmacological experiments, we have identified δ subunit–containing GABARs as the mediators of the residual tonic inhibition in gabra5−/− PCs. Our study is consistent with an important role of tonic inhibition in the control of hippocampal network excitability and highlights selective enhancers of tonic inhibition as promising therapeutic approaches for diseases involving network hyperexcitability.
Details
- Title: Subtitle
- Hippocampal Network Hyperactivity After Selective Reduction of Tonic Inhibition in GABAA Receptor α5 Subunit–Deficient Mice
- Creators
- Joseph GlykysIstvan Mody
- Resource Type
- Journal article
- Publication Details
- Journal of neurophysiology, Vol.95(5), pp.2796-2807
- DOI
- 10.1152/jn.01122.2005
- PMID
- 16452257
- ISSN
- 0022-3077
- eISSN
- 1522-1598
- Language
- English
- Date published
- 05/2006
- Academic Unit
- Neurology; Stead Family Department of Pediatrics; Iowa Neuroscience Institute; Neurology (Pediatrics)
- Record Identifier
- 9984020798602771
Metrics
15 Record Views