The broad goals of this proposal test two hypotheses, (i) that extrasynaptic inhibition of cerebellar granule cells is mediated by receptors made up of the GABAA receptor (GABAR) subunits alpha6, beta3, and delta, and (ii) that receptors of this subunit composition are primary targets for certain general anesthetics, neuroactive steroids, and ethanol. The proposal relies on a combination of molecular approaches and electrophysiological analysis. This project carefully examines granule cell GABAR function in mice deficient in the beta3, and delta subunit genes and in a newly generated """"""""knock-in"""""""" rat carrying a point mutation (R100Q) in the granule-cell specific GABAR gene alpha6.The R100Q mutation is hypothesized to enhance the sensitivity to various GABAR modulators including ethanol and benzodiazepines.
Three specific aims will be undertaken: 1) Electrophysiological analysis of synaptic and extrasynaptic GABAR signals will test whether extrasynaptic inhibition is specifically disrupted in mice lacking the genes for the beta3 and delta subunits. 2) Measurement of synaptic and extrasynaptic signals in wild type and in the alpha6R100Q """"""""knock-in"""""""" rat will be used to evaluate whether extrasynaptic GABARs are key determinants of behaviorally relevant concentrations of ethanol, general anesthetic, and neuroactive steroid action in cerebellum. 3) Mutant, fluorescently-tagged GABAR subunits designed to enhance or impair sensitivity to ethanol or general anesthetics will be introduced into wild type and knockout granule cells and extrasynaptic GABAR signals will be measured. These multidisciplinary experiments rigorously evaluate the molecular basis for extrasynaptic inhibition and test identify molecular determinants of ethanol, anesthetic, and neuroactive steroid action. Advancement in understanding the mechanisms responsible for anesthesia and ethanol intoxication will yield far-reaching clinical and societal benefits including improved treatments for psychiatric disorders and better therapies for severe alcohol abuse.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Program Projects (P01)
Project #
2P01NS035985-06A1
Application #
6946684
Study Section
National Institute of Neurological Disorders and Stroke Initial Review Group (NSD)
Project Start
2005-04-01
Project End
2010-03-31
Budget Start
2005-04-01
Budget End
2006-03-31
Support Year
6
Fiscal Year
2005
Total Cost
$229,450
Indirect Cost
Name
University of California Los Angeles
Department
Type
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
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Cushman, Jesse D; Moore, Mellissa D; Olsen, Richard W et al. (2014) The role of the ? GABA(A) receptor in ovarian cycle-linked changes in hippocampus-dependent learning and memory. Neurochem Res 39:1140-6
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Cushman, Jesse D; Moore, Melissa D; Jacobs, Nate S et al. (2011) Behavioral pharmacogenetic analysis on the role of the ?4 GABA(A) receptor subunit in the ethanol-mediated impairment of hippocampus-dependent contextual learning. Alcohol Clin Exp Res 35:1948-59
Meera, Pratap; Wallner, Martin; Otis, Thomas S (2011) Molecular basis for the high THIP/gaboxadol sensitivity of extrasynaptic GABA(A) receptors. J Neurophysiol 106:2057-64
Meera, Pratap; Olsen, Richard W; Otis, Thomas S et al. (2010) Alcohol- and alcohol antagonist-sensitive human GABAA receptors: tracking ? subunit incorporation into functional receptors. Mol Pharmacol 78:918-24

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