Nitric Oxide Regulation in Alcohol Tolerance

About This Grant

PROJECT ABSTRACT Chronic alcohol consumption leads to pharmacological tolerance of alcohol, promoting excessive alcohol-seeking behavior and resulting in alcohol use disorder (AUD). As of 2018, approximately 5.8% of the US adult population, or 14.4 million adults, suffer from AUD. Therefore, identifying the neurobiological mechanisms underlying alcohol tolerance and developing targeted treatments is crucial. Neurogranin (Ng) is expressed in the post-synapse of glutamatergic neurons and modulates NMDAR- mediated synaptic plasticity and nitric oxide (NO) bioavailability in the medial prefrontal cortex (mPFC). Ng null mice develop alcohol tolerance faster and self-administer more alcohol than wild-type mice following chronic alcohol exposure. Since NMDAR-mediated neuroadaptation occurs in the mPFC to compensate for the effects of alcohol, we hypothesize that Ng levels in the mPFC play a crucial role in NMDAR-mediated NO regulation, which maintains alcohol tolerance development. To address this mechanistic question, we will utilize a 16-hour operant conditioning model to study the high rate of alcohol self-administration and test whether mPFC-specific Ng knockout and overexpression regulate alcohol tolerance and alcohol seeking. We will then elucidate the impact of chronic alcohol on the Ng- NO pathway and its contribution to neuroadaptation in the mPFC using microdialysis and label-free proteomics. Aim 1 will investigate the molecular mechanism by which alcohol reduces Ng expression in the mouse mPFC. Subsequently, we will evaluate the development of alcohol tolerance using rodent behavioral tests following chronic binge alcohol self-administration in mPFC-specific Ng knockout and mPFC-specific Ng overexpression mouse models. Aim 2 will examine whether inducible Ng knockout mice in excitatory neurons (Cre-CaMKII-ERT2-Ng f/f) exhibit increased alcohol tolerance. Then, we will evaluate the effects of chronic alcohol consumption on glutamate-mediated NO neurochemistry using in vivo microdialysis and label-free proteomics. Aim 3 will investigate whether an NO donor (DetaNONOate) in the mPFC can prevent alcohol tolerance development and alcohol seeking in nNOS knock-out mice and glutamatergic neuron-specific Ng knock-out mice. By employing advanced molecular techniques and innovative behavioral assays, our study promises to advance the field significantly and provide a deeper understanding of alcohol's effects on mPFC function. This research addresses a critical gap in understanding alcohol's impact on NMDAR and mPFC. It also provides a novel mechanistic insight focused on the Ng-mediated NO pathway in the mPFC and its role in preventing alcohol tolerance. The outcome of the pharmacological treatment will provide new evidence of how maintaining NO levels in the mPFC precludes the development of alcohol tolerance and suggest potential therapeutic interventions for AUD.