PROJECT SUMMARY Alcohol use disorders (AUDs) manifest from a convergence of characteristics of the individual, the environment, and the alcohol itself. The affective disturbances associated with alcohol withdrawal are examples of this convergence and represent a critical barrier to successful treatment. Reduction of these affective disturbances has been suggested to represent an important conceptual approach to reduce negative reinforcement-based alcohol intake in dependent individuals. However, treatment of these affective disturbances is complicated by data indicating reduced efficacy of antidepressants such as selective-serotonin reuptake inhibitors (SSRIs) in patients with AUDs, and that these traditional treatments can actually increase alcohol intake in some people;; thus, alternate non-monoamine-based treatment approaches for affective symptoms associated with AUDs are critically needed. Here we will test the novel hypothesis that pharmacological augmentation of endogenous cannabinoid signaling could represent an effective treatment for negative affective states associated with alcohol withdrawal including anxiety and depression, and could thereby facilitate abstinence in patients with AUDs. We will test the overall hypothesis that 2- arachidonoylglycerol (2-AG)-mediated endocannabinoid signaling reduces anxiety and depressive-like behaviors associated with acute and protracted alcohol withdrawal in a mouse model of voluntary alcohol consumption. To interrogate the underlying mechanism of this effect, we will test the hypothesis that insula cortical-extended amygdala circuits are hyperactive during alcohol withdrawal and that over activation of this circuit is causally linked to the affective phenotypes observed during alcohol withdrawal. Finally, we will test the hypothesis that 2-AG-mediated inhibition of insula-extended amygdala circuit activity represents a key mechanism by which endocannabinoid signaling reduces alcohol withdrawal-induced anxiety and depressive- like behaviors. These data could provide new insight into the neural circuit mechanisms responsible for generating negative affective states associated with alcohol withdrawal, and reveal novel neuromodulatory mechanisms capable of counteracting these processes. If successful, these studies could support advancement of 2-AG-based pharmacological treatments for AUDs and co-morbid affective disorders.