GABAA R-subunit changes in adolescents by a cytokine/ethanol withdrawal protocol

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DESCRIPTION (provided by applicant): Drinking during adolescence enhances the probability of alcoholism upon reaching adulthood. Likewise, stress has been demonstrated to have an important role in sustaining alcohol abuse. In rats, repeated stresses prior to chronic ethanol sensitized withdrawal-induced anxiety. Based upon stress increasing cytokines in brain in adolescent and adult rats, preliminary research in adolescent and adult rats demonstrated that repeated weekly lipopolysaccharide (LPS) dosing to increase cytokines in brain followed by 5 days of ethanol (LPS/withdrawal protocol) sensitized withdrawal- induced anxiety and increased the 14-GABA(A) receptor subunit in brain 3 days after withdrawal. This effort supports the conclusion that cytokines contribute to the action of stress to enhance adaptive change induced by ethanol. Therefore, studies in adolescent rats will first characterize the time course of the 14 subunit change in cortex during and after the LPS/withdrawal protocol. Subsequently, it will be determine if this increase in the 14 subunit is accompanied by changes in 11, 15, 32, & 4 GABA(A) receptor subunits. To assess if this adaptive change has regional specificity, these assessments will be made in other regions of brain including the hippocampus, thalamus, and amygdala. To examine GABA(A) receptor function, electrophysiological studies will be performed to test if changes in synaptic and extrasynaptic GABA function occur for an extended period after the LPS/withdrawal protocol. Additionally, pharmacological studies will be carried out to identify selected GABA(A) receptor subunits at these cellular sites in chosen brain regions. Finally, studies will be undertaken to determine if blocking sensitization of ethanol withdrawal-induced anxiety induced by the LPS/withdrawal protocol will prevent the adaptive change in GABA(A) receptor subunits and diminish electrophysiological changes at synaptic and extrasynaptic sites. This latter strategy will be accomplished by preventing the LPS/withdrawal protocol behavioral sensitization of ethanol withdrawal-induced anxiety by administering drugs that block this sensitization when given prior to each of the weekly LPS doses injected before ethanol exposure. This work will test the hypothesis that the LPS/withdrawal protocol induction of persistent adaptation in GABA(A) receptor function and functional changes at synaptic and extrasynaptic sites in adolescent rats will correlate with the sensitization of withdrawal-induced anxiety induced by this protocol. The data collected should provide a foundation for understanding the role cytokines contribute to stress support of the functional pathology that increases adolescent susceptibility to continued alcohol abuse as adults. PUBLIC HEALTH RELEVANCE inking during adolescence enhances the probability of being an alcoholic during adulthood. Additionally, stress is an important aspect of sustaining relapse to drinking. Since cytokines contribute to stress responses, this proposal examines adaptive changes in adolescent rats that result from an interaction of cytokines and ethanol.