CART II signaling effects on escalated alcohol intake

About This Grant

PROJECT SUMMARY Alcohol use disorder (AUD) is a chronic disease that affects approximately 30 million people, resulting in $250 billion in lost productivity, and associated healthcare costs. Although three FDA-approved medications are available to treat AUD, achieving long-term abstinence remains challenging, indicating new therapeutic approaches would be beneficial. The cocaine and amphetamine regulated transcript is a neuropeptide involved in several physiological processes, including AUD. However, studies of CART II during AUD have been prevented by the lack of a known receptor. We recently identified the Lysophosphatidic Acid Receptor 2 (LPAR2) as a high affinity receptor for CART II in the brain. We used cell-based assays and in vivo pharmacology tools to show that LPAR2 is mediating CART II behavioral effects. Our preliminary data show that brain administration of CART II during intermittent alcohol 2-bottle choice (IA2BC) reduces ethanol intake in wild-type male (WT) without altering water or sucrose consumption. However, the effects of CART II on escalated drinking, a hallmark of AUD, have not been investigated. Previous work showed that during alcohol withdrawal extracellular glutamate (GLU) levels in the nucleus accumbens (NAcc) are elevated and this contributes to neuroadaptations occurring in the medium spiny neurons (MSNs). Our preliminary data demonstrates that LPAR2 is expressed in the NAcc and confirms LPAR2 couples with Gi/o protein suggesting CART II signaling may decrease GLU vesicular release in the NAcc and/or decrease the excitability of D1-MSNs. However, the presynaptic and postsynaptic effects of CART II-LPAR2 signaling in the NAcc have not been established. The overarching hypothesis of this proposal is that CART II – via LPAR2 – reduces escalated ethanol drinking and reverses the ethanol-induced neuroadaptations. Thus, we propose to use the well-established chronic-intermittent ethanol vapor exposure interspersed with two-bottle choice (CIE-2BC) model in WT and LPAR2 KO mice of both sexes to fully examine the effects of CART II-LPAR2 signaling on escalated alcohol intake (Aim 1), the pre-synaptic and post-synaptic effects on D1-MSNs excitability in the NAcc (Aim 2) and CART II region-specific effects on GLU release in the NAcc (Aim 3). To validate that the effects of CART II on AUD are mediated by LPAR2, we will employ both sexes and LPAR2 KO mice. Collectively, the expected results will elucidate the CART II-LPAR2- mediated mechanism on AUD, facilitating the development of novel therapeutics. An experienced team of mentors and career advisors will provide training critical for the candidate’s short- and long-term success. The PI will be trained at Virginia Tech (VT) on the design, execution, and interpretation of behavioral models of alcohol use, and ex vivo electrophysiology of distinct subpopulations of neurons (both at VT and Scripps Research Institute). Finally, the professional development plan will prepare the candidate to transition to an independent position and create her future research program in studying the interaction between neuropeptides and NTs in multiple neuronal subpopulations during AUD and other substance use disorders.