The role of corticotropin releasing factor in binge-like ethanol drinking

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DESCRIPTION (provided by applicant): Alcoholism and relapse in abstinent alcoholics are major health problems world-wide and current research is underway to identify potential pharmaceutical treatments for these disorders. However, heavy alcohol use and binge alcohol drinking by non-dependent individuals have received far less attention. A 'binge' is defined by the National Institute on Alcohol Abuse and Alcoholism (NIAAA) as a pattern of drinking that produces blood ethanol concentrations (BECs) greater than 0.08% (80 mg/dL) within a short period of time. Of great concern, regular binge drinking significantly increases ones risk of developing ethanol dependence. Thus, it is of paramount importance to identify neurochemical pathways in the brain that modulate binge drinking as such knowledge will provide insight into novel pharmaceutical treatments that will protect against this dangerous behavior. We have found that binge-like ethanol drinking increases corticotropin releasing factor (CRF) immunoreactivity (IR) in the central amygdala (CeA) and that a type-1 receptor (CRF1R) antagonist, when injected into the CeA, protects against excessive binge-like drinking in C57BL/6J mice. On the other hand, CRF1R antagonists fail to alter moderate non-binge-like ethanol intake. These observations parallel evidence that CRF1R antagonists blunt dependence-like drinking without altering ethanol intake in non-dependent animals. The guiding hypothesis for this grant is that acute binge-like ethanol drinking transiently engages CRF signaling in the CeA, and at sites that are innervated by CRF pathways arising from the CeA, and drives continued excessive ethanol intake. We further hypothesize that increased CRF signaling fails to "normalize" with repeated binge-like drinking episodes, ultimately contributing to persistent increases in alcohol drinking. The proposed Aims will use powerful and innovative electrophysiological, histological, genetic, and behavioral techniques to determine if: A) A history of repeated binge-like drinking episodes will be associated with changes in CRF and CRF receptor levels and function (Aim 1), B) CRF1R antagonist and a CRF2R agonist will protect against binge-like ethanol drinking when injected into the CeA and regions that receive CRF innervation from the CeA (Aim 2), and C) inhibition of CRF-producing neurons in the CeA and/or bed nucleus of the stria terminalis (BNST) with designer receptors that are exclusively activated by designer drugs (DREADDs) will protect against binge-like ethanol drinking, and DREADD-induced activation of CRF-producing neurons in these regions will increase binge-like drinking (Aim 3). These highly innovative projects will provide a shift in pre-clinical alcoholism research by providing insight into the role for CRF1R and CRF2R signaling in excessive binge-like ethanol drinking and the transition to a dependence-like state, and establish new technologies for studying the neurocircuitry that modulates excessive ethanol intake.