Increased anxiety levels are commonly reported during ethanol withdrawal and are considered a potent deterrent for the cessation of ethanol consumption. The central hypothesis of this proposal is that aS- containing (a5*) nicotinic acetylcholine receptors (nAChRs) are important modulators of the anxiety-related manifestations of alcohol withdrawal. This hypothesis is based on data from the lab showing that lack of the a5 nAChR subunit reduces anxiety levels in basal conditions and during ethanol withdrawal. In addition, smoking in the alcohol dependent population is estimated to be in excess of 80 percent, suggesting that nicotine might be consumed in the attempt to mitigate the anxiety produced by alcohol withdrawal. Aim 1 will examine the role of a5* nAChRs in the anxiety-related manifestations of ethanol withdrawal through a series of behavioral experiments in a5 +/+ and a5 -/- mice chronically treated with alcohol. Aim 2 will examine the interaction between nicotine and alcohol by examining anxiety-like responses in ethanol and nicotine treated animals undergoing withdrawal of one drug at a time or both drugs simultaneously. Experiments will be conducted in wild type and a5 -/- mice to assess the role of the aS nAChR subunit in the nicotine/ethanol interaction. Aim 3 will address the hypothesis that the a5* nAChRs expressed in the medial habenula/ interpeduncular nucleus (MHb/IPN) axis are critical for the anxiety-like manifestations of ethanol withdrawal. These experiments are based on the fact that the MHb/IPN axis is crucial for the expression of nicotine withdrawal and that the habenular complex participates in stress and depression responses in humans. The experiments will use lentiviral constructs to either knock back a5 into the MHb/IPN of aS -/- mice or knock down a5 into the MHb/IPN of C57BI/6J mice. The co-abuse of alcohol and tobacco leads to an increased risk of cancer and other diseases, resulting in a burden to the health care system. The identification and understanding of the neuronal circuits underlying withdrawal will be useful in the design of better cessation strategies in subjects with alcohol and nicotine co- abuse. Our studies are of particular interest based on the recent literature highlighting the role of a5 single nucleotide polymorphisms in alcohol and nicotine dependence. PUBLIC HEALTH RELEVANCE: The goal of this NRSA fellowship training is to further my development as a neuroscientist and prepare myself for a career as a professor at either a research university or a minority serving institution. My interests in neuroscience began as a result of my undergraduate experience in research and as a health educator, my interest in health disparities, and my experiences in graduate coursework. I am presently interested in the neural mechanisms underlying addiction, in particular to nicotine and alcohol. The experiments that I propose in this application will allow me to cultivate my critical thinking abilities through formulating hypotheses, designing experiments to test these hypotheses using modern molecular biological tools, and drawing appropriate conclusions from resulting data. As I was drawn to the field of neuroscience by its potential to explain human behavior, after graduating with a Ph.D., I hope to continue my research in addiction as a postdoctoral fellow studying this disease at the genetic and systems level. Ultimately, I plan to head my own research laboratory studying addiction through complementary molecular/cellular and systems neuroscience approaches as well as provide the type of mentorship that has paved the way to my success to other students. My scientific career goal is to further our understanding of addiction from the level of molecular events to the underlying processes that foster abuse.