The role of BNST PKCdelta neurons in compulsive ethanol intake

PROJECT SUMMARY/ABSTRACT Alcohol Use Disorder (AUD) is a chronic, relapsing disease, affecting 10.6% of United States adults. In the treatment seeking population, periods of abstinence define a highly vulnerable portion of the AUD cycle, as during this time individuals report heightened craving and experience increased negative affect. Given the heterogeneity of alcohol use and behaviors observed in the clinical population, animal models highlighting individual differences may provide novel insight to the development of targeted therapeutic interventions. We propose the use of an operant conditioning task known as Structured Tracking of Alcohol Reinforcement (STAR) to define subpopulations of mice displaying high, low, or compulsive (aversion resistant) ethanol intake behaviors. Our data suggest that mice displaying compulsive drinking may represent a particularly vulnerable subpopulation, as these mice display greater ethanol seeking in protracted abstinence. Our data recoding calcium transients during this ethanol seeking session implicate the bed nucleus of the stria terminalis (BNST) as a potential driver of maladaptive behavior in the compulsive phenotype. Part of the extended amygdala abstinence network, the BNST is a critical brain region for the integration of negative affect and alcohol-related behaviors. However, the BNST is highly heterogenous, composed of specialized subpopulations of neurons. One largely unstudied population of BNST neurons are the protein kinase C delta (PKCδ)-expressing neurons. Despite strong support for central amygdala (CeA) PKCδ neurons in both aversion-resistant ethanol intake and reinstatement of ethanol-seeking behaviors, no studies have examined BNST PKCδ neurons in the context of ethanol. However, our lab recently demonstrated a direct projection from CeA PKCδ neurons to BNST PKCδ neurons, and preliminary data demonstrate engagement of BNST PKCδ neurons during an ethanol drinking bout as well as changes in activity following cycles of ethanol exposure and withdrawal. Altogether these data support BNST PKCδ neurons as a novel circuit component of compulsive ethanol intake. These findings led us to develop our central hypothesis that abstinence from ethanol exposure induces changes in BNST PKCδ neuron activity and their associated circuitry to drive compulsive ethanol intake. To test this hypothesis, the mentored (K99) phase will provide training in in vivo fiber photometry to evaluate adaptions in BNST PKCδ calcium transients across an abstinence period during operant behavior (Aim 1) and ex vivo slice wide-field calcium imaging to dissect population dynamics in BNST PKCδ calcium transients in response to ethanol exposure (Aim 2). The independent (R00) phase will evaluate adaptations in BNST PKCδ neuron afferents, exploring the ability of dysregulation in these areas to modulate compulsive intake through their influence on the BNST (Aim 3). These proposed studies and related career development training plan in this Pathway to Independence Award collectively provide the ideal mechanism to transition to a career as an independent addiction neuroscientist.