Orexinergic neurons, ethanol dependence, and voluntary ethanol consumption

About This Grant

Project Summary Alcohol use disorder (AUD) is a prevalent, affecting over 10% of Americans, with only a fraction of individuals seeking treatment. Chronic alcohol exposure induces maladaptive changes in neuronal physiology, particularly within neural circuits that mediate reward and consumption behaviors, hallmarks of AUD that render treatment difficult and increases the likelihood of relapse. Despite substantial progress in understanding neurotransmitter- mediated changes in AUD, the role of neuropeptides such as orexin (hypocretin) remains underexplored. Orexin is a hypothalamic neuropeptide that contributes to a number of physiological conditions, including regulation of arousal, feeding, and stress. Orexinergic neurons from the lateral hypothalamic area (LHA) innervate a number of brain regions implicated in AUD, such as the ventral tegmental area (VTA) and nucleus accumbens (NAc). In my preliminary data, I have found that chronic voluntary EtOH consumption leads to activation of orexinergic neurons in the LHA in male and female C57BL/6J mice. Furthermore, I have demonstrated that I can track orexinergic activity in a free-moving mouse while it is consuming EtOH through the use of fiber photometry and the orexin peptide sensor, OxLight1. This proposal aims to investigate the impact of alcohol dependence on orexinergic circuits, particularly the LHA-VTA pathway, and its role in excessive alcohol consumption. Using cutting-edge tools, including the OxLight1 biosensor for real-time orexin monitoring, optogenetics for pathway- specific neuronal silencing, and whole-cell patch-clamp electrophysiology, this study will elucidate the functional changes in orexinergic activity in male and female mice following chronic intermittent ethanol (CIE) exposure. The innovative approach includes sex-specific and within subject analyses and behaviorally guided experiments to address critical gaps in the field. Aim 1 of this proposal will determine how silencing LHA orexinergic neurons projecting to the VTA modulates voluntary alcohol consumption in ethanol-dependent mice. Aim 2 of this proposal will assess functional adaptations in the LHA orexinergic circuits to regions implicated in AUD following ethanol dependence and their impact on voluntary alcohol consumption. The expected outcomes will reveal how chronic alcohol exposure alters orexinergic signaling, contributing to excessive drinking and relapse. These findings will enhance our understanding of AUD's neural mechanisms, identify potential sex differences, and detect therapeutic strategies targeting orexinergic pathways. This research holds significant translational potential, advancing efforts to mitigate the global burden of AUD.