Alcohol (ethanol) dependence and relapse in abstinent alcoholics are major health problems throughout the world and neurochemical pathways that modulate these disorders are currently under investigation. However, the neurobiology underlying binge drinking, a dangerous pattern of behavior that proceeds and contributes to dependence, has received far less attention. Thus, it is of paramount importance to identify the neurocircuitry in the brain that modulates binge drinking as such knowledge will provide insight into the initial stages of alcohol use disorders (AUDs). In the last funding period of this grant we showed that NPY signaling in regions of the extended amygdala modulate binge-like ethanol drinking via mechanisms that overlap with NPY mechanisms involved with dependence-like intake. The goal of the present application is to extend our understanding of the NPY neurocircuitry that modulates binge-like ethanol drinking with a novel focus on NPY neurocircuitry originating in the medial prefrontal cortex (mPFC). The mPFC provides top-down regulation of the extended amygdala, in part through a glutamatergic mPFC ? basolateral amygdala (BLA) circuit that is modulated by Y1 receptor (Y1R) signaling. Knowledge obtained from the proposed studies will greatly expand our understanding of the NPY neurocircuitry that modulates binge-like ethanol intake by linking together cortical and extended amygdala circuitry. The mPFC integrates information from limbic and cortical regions and has been implicated in modulating goal-directed (via prelimbic (PL) circuits) and habitual (via infralimbic (IL) circuits) seeking of ethanol and drugs of abuse, as well as anxiety and fear learning. Recent evidence has revealed a critical role for NPY signaling in the mPFC, and we have provided strong pilot evidence showing that infusion of an Y1R agonist into the PL, but not IL, region of the mPFC blunts early-experience binge drinking, and that chemogenetic silencing of Y1R+ neurons originating from the PL and projecting to the BLA blunt early-experience binge intake. The proposed aims will use powerful and innovative chemogenetic and transgenic tools, electrophysiology, and histological approaches to determine if a history of binge-like ethanol drinking induces alterations of NPY and NPY receptor signaling in the mPFC (Aim 1), if site-directed infusion of a Y1R agonist or Y2R antagonist, or viral-mediated overexpression of NPY in the mPFC blunts binge-like ethanol drinking (Aim 2), and if chemogenetic silencing of Y1R+ pyramidal neurons of the mPFC and which project to the BLA blunt binge-like ethanol intake (Aim 3). Together results from these proposed studies will address a critical gap in the literature regarding the role of the mPFC, NPY signaling in this region, and the functional interaction between the mPFC and extended amygdala in the modulation of binge-like ethanol intake in mice.
Research has established that compounds aimed at neuropeptide Y (NPY) receptors are protective against dependence-induced alcohol drinking, and our recent findings show that compounds targeting NPY receptors are also protective against excessive binge-like drinking in mice when targeted to regions of the extended amygdala. Expected results in the current application will significantly expand our recent observations by showing the NPY circuits in the medial prefrontal cortex modulate binge-like ethanol drinking by providing top- down modulation of the extended amygdala.
