Excessive alcohol (ethanol) intake in a binge-like fashion has emerged as a significant health risk in both males and females. Binge drinking is defined as a pattern of drinking that leads to blood ethanol concentrations (BEC) above legal limit of intoxication within a relatively short period of time. Among several neurochemical and neuropeptide systems implicated in binge drinking, recent findings have implicated a role for the dynorphin/kappa opioid receptor (DYN/KOR) system. Recently we showed that systemic administration of a KOR agonist increased while a KOR antagonist decreased ethanol intake in a mouse model of binge drinking. Further, using a prodynorphin-IRES-Cre mouse line to target an inhibitory (hM4Di) DREADD in DYN-containing (DYN+) neurons in the central amygdala (CeA), we showed chemogenetic inhibition of these neurons (via systemic CNO injection) reduced binge drinking. The bed nucleus of the stria terminalis (BNST) is a functionally important target of the CeA and both structures are implicated in motivated behavior, including ethanol drinking. Targeted anterograde viral tracing of DYN+ neurons in the CeA showed dense terminal fields within the BNST. This, along with relevant pilot data suggest that DYN/KOR activity within the CeA-BNST pathway is involved in binge drinking. Thus, the overall hypothesis to be tested in this project is that increased DYN/KOR activity within the CeA-BNST pathway contributes to binge-like ethanol consumption. The proposed research plan will employ a comprehensive approach that entails using pharmacological, chemogenetic, and fiber photometry techniques to examine the contribution of DYN/KOR activity within the CeA-BNST pathway to binge drinking in male and female mice. Studies in Aim 1 will examine the effects of pharmacologically manipulating KOR in the BNST on binge ethanol drinking in male and female C57BL/6J mice. Studies in Aim 2 will utilize a targeted chemogenetic approach to examine the effects of ?silencing? and activating DYN+ neurons in the CeA-BNST pathway on binge ethanol drinking in male and female mice.
Aim 3 will utilize fiber photometry to selectively measure activity in DYN+ neurons within the CeA-BNST pathway while mice are drinking in the binge ethanol drinking model. Results from this project will advance our understanding of the role of the DYN/KOR system within extended amygdala (CeA-BNST pathway) in binge ethanol drinking. Further, this research plan will serve as an ideal platform for my comprehensive training plan that is designed to provide me with the opportunity to acquire and apply new technical skills that will enhance my goal of pursuing a research career in the alcohol field.
Brain mechanisms underlying excessive binge-like ethanol drinking are not well understood. This project will use a multifaceted approach involving pharmacology, chemogenetics, and fiber photometry to interrogate the dynorphin/kappa opioid neuropeptide system within extended amygdala circuity as it relates to excessive binge- like ethanol consumption. Results from these studies will provide important information regarding whether this neuropeptide system has potential as a target for development of therapeutics in treating individuals that engage in dangerous, excessive levels of ethanol drinking.
