ETHANOL, CALCIUM CHANNELS, AND PROTEIN KINASE C

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The overall goal of this project is to determine molecular events that underlie cellular adaptation to alcohol with the hope of identifying novel drug targets for treatment of alcoholism. Considerable evidence implicates voltage-dependent calcium channels in alcohol consumption and dependence in animals. Prior work has focused mainly on L-type, voltage- gated calcium channels, which are inhibited by ethanol and are up- regulated by chronic ethanol exposure in vitro. Moreover, binding sites for omega-conotoxin GVIA, a specific N channel antagonist, are increased in mouse hippocampus following chronic exposure to ethanol. In PC12 cells, up-regulation of N channels by chronic ethanol exposure requires protein kinase C (PKC)epsilon. The first goal of this project is to determine if up- regulation of N-type channels by ethanol is reversible and leads to reversible changes in N channel function. Subsequent studies will investigate whether ethanol increases N channel density by increasing channel subunit mRNA or intracellular trafficking of subunit proteins by PKCepsilon-dependent mechanisms. Using a newly created PKCepsilon knockout mouse, the role of PKCepsilon in alcohol preference, tolerance, and dependence will be examined in behavioral studies of two-bottle preference, loss of righting reflex, and alcohol withdrawal seizures. Finally, the role of PKCepsilon in ethanol-induced up-regulation of N channels in vivo will be examined using these PKCepsilon knockout mice. These studies will provide specific information about the role of PKCepsilon in mediating ethanol-induced changes in functional N channels in vitro and in vivo. Important information will be obtained regarding the role of PKCepsilon in regulating alcohol preference, tolerance, and dependance in animals. These results will advance our knowledge about mechanisms underlying drinking behavior and may identify N-type channels and PKCepsilon as new targets for development of therapeutic agents to treat alcoholism.