Symptoms of withdrawal are believed to contribute significantly to sustaining alcoholism. Pharmacological evidence has been obtained that endogenous compounds, including a benzodiazepine (BZD)-inverse agonist, CRF, and glutamate, play a major role in withdrawal-induced anxiety, a symptom observed during withdrawal from chronic ethanol treatment (withdrawal). Further withdrawal produces changes in metabolic activity in specific regions of brain with are proposed to be due to release of endogenous transmitters which contribute to anxiety. In addition, comparison of male and female rats have revealed gender differences when rats were performing conflict tasks during withdrawal. From such data, we suggest the anxiety and increased metabolic activity observed during withdrawal are cause by an orchestrated release of these endogenous compounds that act on central BZD receptors (CBRs), peripheral BZD receptors (PBRs), CRF, and glutamate receptors and that this increased release during withdrawal is influence by gender. To gain support of this view, Specific Aim I will identify changes in metabolic activity using 2- deoxyglucose (2-DG) accumulation and Fos expression to identify brain areas involved in the anxiety response to a challenge with air puff or elevated-plus maze in male and female rats in the presence and absence of withdrawal. Subsequently, we will use antagonists of CRF, CBRs, PBRs and glutamate receptors and antisense deoxynucleotides for the peptides to see how specific metabolic events and the anxiety induced by ethanol withdrawal are affected.
In specific Aim II, we will confirm and extend observations that the endogenous inverse agonist, diazepam binding inhibitor (DBI), which acts on CBRs and PBRs, as well as the CRF peptide is altered after chronic ethanol, during withdrawal, and when male and female rats are challenged with tasks reflecting anxiety during and in the absence of withdrawal. This determination will be made by measuring content of the peptides with radioimmunoassay or quantitative immunohistochemistry. The determination of the peptides will be coupled to measurement of their levels of mRNA within specific regions of brain using in situ hybridization.
Specific Aim III will test the hypothesis that treatment with antagonists of the endogenous compounds, which blocked anxiety and central metabolic activity caused by a single withdrawal, will prevent sensitization of symptoms resulting from multiple withdrawals from chronic ethanol treatment. Once completed, these aims are expected to support the hypothesis that endogenous compounds acting on CBRs, PBRs, glutamate, or CRF receptors in specific regions of brain contribute to metabolic changes and to the anxiety to differing degrees in males and females during withdrawal from chronic ethanol exposure and that repeated withdrawals accentuate these withdrawal-induced changes.
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