Zoe A. McElligott - US grants

[unreadable] DESCRIPTION (provided by applicant): Stress and anxiety are two factors that contribute to the prevalence of alcoholism in our society. The bed nucleus of the stria terminalis (BNST) is a region of the brain where reward circuitry and stress pathways converge, and where it has been shown that ethanol increases Fos activity. Additionally, the BNST is heavily innervated by adrenergic afferents that are involved in behavioral paradigms of stress induced reinstatement of drug seeking. These afferents modulate the HPA axis via the aradrenergic receptor (ch-AR) under conditions of prolonged psychological stress. Furthermore, it has recently been shown that antagonizing the arAR in ethanol dependent animals experiencing withdrawal attenuates self administration. I have recently described a long term depression (LTD) of glutamatergic inputs into the BNST that is mediated by Qi-AR activation. Using electrophysiological, genetic and pharmacological approaches I will characterize arAR-LTD (Aim 1) and investigate the synaptic maintenance mechanism by which activation of the ch-AR produces LTD (Aim 2). Furthermore, I will test the hypothesis that arAR-LTD is activated in vivo in animals experiencing withdrawal from chronic intermittent ethanol exposure (CIE) and that this functionally alters HPA axis output and anxiety (Aim 3). Alcohol abuse costs the United States of America over one hundred billion of dollars annually in lost wages, health care, prison/institutional and other socio-economic costs. Stress and anxiety are two factors known to impact drinking behavior and can often contribute to consumption in an addicted state. It is beneficial to society, therefore, to gain a greater understanding of how stress and anxiety affect the brain of alcoholics and, thus, to find pharmacological targets for therapies to halt the progression of this terrible affliction. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Alcohol use disorders have an enormous societal and fiscal impact in the United States. Moreover, alcohol is the third leading cause of preventable death (Mokdad et al., 2004). Elucidating the neuronal circuitry that contributes to the rewarding properties of alcohol may provide insight into therapeutic mechanisms for treating alcohol use disorders. The central nucleus of the amygdala (CeA) has been shown to play a role in regulating various aspects of alcohol drinking behavior, however, the CeA is a heterogeneous nucleus where different genetically defined populations may contribute to ethanol related behaviors in different ways. This proposal aims to assess the causal role of CeA-neurotensin (NTS) neurons in mediating ethanol intoxication and self-administration using cutting edge tools. I will perform immunohistochemical, behavioral and electrophysiological experiments. In particular I will investigate the projection to the parabrachial nuclei (PBN) in the hindbrain, a region that is thought to play a major role in stress and anxiety. Through this research I plan to show that CeA-NTS neurons that project to the PBN are activated in response to alcohol and associated cues and mediate some of the rewarding properties of alcohol. These experiments will uncover new neuronal circuitry and mechanisms that may contribute to alcohol use disorders and allow for future targets for the treatment of this pathology.

PROJECT SUMMARY The opioid epidemic in the United States is profound, with an annual economic burden of $95.8 billion dollars (2016 dollars) and a total cost of over $1Trillion since 2001. Moreover, drug overdose is now the no. 1 cause of accidental death with over 72,000 lives lost in 2017, and opioid overdoses account for over 60% of these deaths. In order to develop pharmacological and behavioral therapies to treat opioid use disorder (OUD), it is important to understand the neural circuitry and neuroadaptation that occurs following opioid use and withdrawal. Disorders on the affective spectrum often exhibit high comorbidity. Therefore, it is imperative to understand how opioids alter critical circuits and neurotransmitters that regulate addiction-like behaviors, aversion/anxiety and the response to stress. A node in the extended amygdala, the bed nucleus of the stria terminalis (BNST), receives the densest innervation of norepinephrine (NE, a stress responsive neurotransmitter) in the brain. The BNST is a major contributor to opioid withdrawal behaviors and previously, we demonstrated that morphine exposure and withdrawal modulates BNST NE release and uptake mechanisms in rats. Our preliminary data demonstrate that chronic stress enhances the same noradrenergic circuitry mice, and that opioid exposure and withdrawal modulates NE neurons. Furthermore, in mice we observe sex specific acute withdrawal behaviors, withdrawal induced disruption of sleep rhythms, and anxiety-like behavior in protracted abstinence. The BNST is a sexually dimorphic brain region, and we observe further sex differences in (and some similarities) in BNST physiology. Intriguingly, our data suggest that there may be reductions in excitatory transmission in select circuitry following opioid withdrawal, which may ultimately alter BNST output to classical reward circuits. These data inform the central hypothesis of our proposal investigated in 3 aims: opioid withdrawal 1. enhances the synaptic drive onto NE neurons innervating the BNST, 2. facilitates enhanced noradrenergic transmission within the BNST, and 3. induces glutamatergic plasticity within the BNST intensifying opioid withdrawal syndrome related behaviors.

Project Summary Alcohol use disorders (AUDs) impart a huge financial (in excess of $250 billion) and societal strain. In order to develop pharmacological and behavioral therapies to treat AUDs, therefore, it is important to understand the neural circuitry and neuroadaptation that occurs in the transition to excessive consumption of alcohol use. The focus of this application is on a population of neurotensin (NTS) neurons the central nucleus of the amygdala (CeA). Utilizing genetic, cre-recombinase strategies in conjunction with selective lesioning (caspase3) and optogenetic (channel rhodopsin) strategies, we have found that these neurons, via their projections to the parabrachial nucleus (PBN), regulate both excessive consumption of alcohol, and reward-like behaviors. In this proposal we hypothesize that GABAergic signaling within the NTSCeA and in the NTSCeA?PBN mediates reward and ethanol consumption behaviors. We will explore this hypothesis over 3 converging aims. Aim 1 will probe the role of signaling molecules within NTSCeA neurons on reward, alcohol consumption and appetitive behavior. Aim 2 will further probe the role of GABAergic signaling within the NTSCeA?PBN projection. Finally, Aim 3 will explore physiological adaptation within these circuits. Together, these aims provide an innovative framework to discern how specific projections within the brain are influencing the reward behavior and consumption of alcohol.