ETHANOL MECHANISMS IN GABAAR GENE TARGETED MICE

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DESCRIPTION: (Adapted from the Investigator's Abstract): The focus of this project continues to be transgenic dissection of the putative molecular targets of ethanol to explain the neurophysiological basis of action. The central hypothesis is that the type A gamma-aminobutyric acid receptor (GABA-A receptor) is a critical component of the mechanism of action that contributes to the behavioral response to ethanol. Mutants have been/ or will be created that harbor specific alterations in genes intimately involved in the neurochemical response to GABA. The mice are being/ will be analyzed with a battery of tests that span the molecular, cellular and behavioral levels; such a multi-level approach will allow responses to be properly attributed to a site of ethanol action. Specifically, mouse lines that ubiquitously lack either the beta 3, gamma 2L or delta subunits of the GABA-A receptor have already been produced; the electrophysiologic and behavioral responses of these animals to ethanol is being investigated. Two new mouse lines are being created (and will be analyzed) that harbor tissue-specific knockouts of the gamma isoform of protein kinase C; this locus has been demonstrated to be critical for behavioral responses to ethanol. The strategic advantages inherent in this conditional knockout approach are that untoward developmental effects of the genetic alteration are avoided, and the technique allows one to map the neuroanatomic location(s) that contribute to the behavioral phenotype observed. Three additional novel mouse lines are being created and will be analyzed; these are: (a) a ubiquitous knockout of the alpha1 subunit of the GABA-A receptor, (b) a transgene that expresses an Ala (291) Trp point mutation in the alpha1 subunit of the GABA-A receptor; the investigators have demonstrated electrophysiologically that this mutation abolishes ethanol enhancement of GABA action; a knockin mutation of the same Ala (291) Trp mutation that replaces the endogenous alpha1 gene. Together, these studies provide an integrated approach toward understanding how ethanol exerts its effects on the central nervous system.