P 1/7: Stress-enhanced drinking in alcohol dependence: Role of dynorphin/KOR activity in extended amygdala circuitry

Howard Becker

PROJECT SUMMARY
While stress is known to be a significant factor in triggering relapse and promoting heavy alcohol (ethanol) consumption, mechanisms underlying the interaction between stress and ethanol drinking, particularly within the context of dependence, are not well understood. During the current funding period, we examined stress- ethanol interactions using our well-established dependence model that involves repeated weekly cycles of chronic intermittent ethanol (CIE) exposure alternating with weekly voluntary limited access drinking test sessions. Specifically, we found that repeated brief exposure to forced swim stress (FSS) prior to ethanol drinking test sessions significantly increased drinking in dependent (CIE-exposed) mice, but did not alter intake in nondependent mice. Additional preliminary data we collected implicate a role for the dynorphin/kappa opioid receptor (DYN/KOR) system in mediating this reliable and robust stress-induced selective enhancement of drinking in CIE-exposed mice. Stress and chronic ethanol exposure are known to produce adaptations in stress-related neuropeptides (DYN/KOR and CRF systems) in the central amygdala (CeA) and the bed nucleus of the stria terminalis (BNST), key structures within extended amygdala circuitry that are integral to stress reactivity and motivational/reward processes. The overall objective of this proposal is to utilize our CIE- FSS Drinking model to examine the role of adaptations in DYN/KOR activity and potential CRF-DYN/KOR interactions within extended amygdala circuitry (CeA and BNST) in mediating the ability of stress to promote excessive ethanol consumption in male and female mice. Specifically, studies will utilize molecular biology (qPCR) procedures to examine changes in Pdyn and Crf mRNA expression in CeA and BNST at different time points in the model. Studies also will employ chemogenetic (DREADDs) and pharmacological approaches to selectively modulate DYN/KOR activity in the CeA and the CeA-BNST pathway, as well as examine interactions of CRF and DYN in mediating stress-enhanced drinking associated with dependence. Site-specific administration of KOR and CRF1R/CRF2R ligands in combination with the chemogenetic approach will probe for specificity of effects on drinking in the model. Thus, proposed studies will employ molecular biology, chemogenetic, and pharmacological approaches to interrogate the contribution of DYN/KOR activity and potential CRF-DYN/KOR interactions in the CeA and the CeA-BNST pathway in mediating stress- enhanced drinking associated with dependence. Collectively, results from this project will provide new insights on mechanisms underlying adaptations in stress-related neuropeptides within extended amygdala circuitry that underlie the ability of stress to further escalate drinking associated with ethanol dependence. The overall goal is to identify new targets that will aid in development of more effective treatment strategies for controlling stress-related excessive drinking, and alcohol use disorders in general.