Defense Date

2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Pharmacology & Toxicology

First Advisor

Michael F. Miles

Abstract

Alcoholism is a complex neuropsychiatric disease that is characterized by compulsive alcohol use and intensifying cravings and withdrawals, often culminating in physiologic dependency. Fundamental alterations in brain chemistry underlie the transition from initial ethanol exposure to repetitive excessive use. Key mediators of this adaptation include changes in gene expression and signal transduction. Here we investigated gene expression pathways in prefrontal cortex and nucleus accumbens following acute or chronic ethanol treatment, to identify genes with potentially conserved involvement in the long-term response of the corticolimbic system to repeated ethanol exposure. We investigated Gsk3b, which encodes glycogen synthase kinase 3-beta, as a highly ethanol responsive gene associated with risk for long-term maladaptive responses to ethanol. On the level of the protein, we found that GSK3B and to a lesser extent the GSK3A isoform showed robust increases in inhibitory phosphorylation following acute ethanol. This inhibition may underlie aspects of the behavioral response to acute ethanol, as pre-treatment with a GSK3B inhibitor (tideglusib) augmented ethanol’s locomotor effects. Following long term ethanol exposure, we re-tested GSK3B phosphorylation and found that its ethanol response is blunted, consistent with molecular tolerance as a corollary to increased consumption. As the prefrontal cortex (PFC) plays a vital role in the reward pathway via its glutamatergic projections to the nucleus accumbens, we investigated the role of the Gsk3b gene specifically in PFC and in glutamatergic neurons. Overexpression of Gsk3b in the PFC robustly increased ethanol consumption, while deletion in Camk2a-positive neurons significantly attenuated ethanol consumption. Pharmacologic antagonism of GSK3B also decreased drinking in xv a model of binge-like consumption. Collectively this data implicates GSK3B as a mediator of excessive ethanol intake via its kinase activity, wherein inhibition of the kinase via phosphorylation exerts a protective effect in the context of acute ethanol, but desensitizes with repeated exposure.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

4-23-2018

Available for download on Thursday, May 30, 2019

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