Role of hypothalamic-specific POMC deficiency in alcohol reward and drinking



 DESCRIPTION (provided by applicant): Opioidergic mechanisms particularly through beta-endorphin are involved in reward and drug addiction. In different rodent models of alcohol intake, opioid receptor antagonists decrease alcohol consumption and relapse-like drinking. Beta-endorphin is encoded by pro-opiomelanocortin (POMC) gene. Using Sardinian alcohol-preferring rats and C57BL/6J, we recently found that voluntary alcohol drinking for 2 weeks increases POMC gene expression in the hypothalamus of both rats and mice. Our hypothesis is that alterations of hypothalamic POMC gene expression are critical to alcohol-induced reward and the development of alcohol drinking behaviors, dependence and relapse. In transgenic mice, deletion of POMC nPEs (hypothalamic- specific POMC enhancers) abolishes POMC expression selectively in the hypothalamus, but with normal pituitary POMC cells. Our first goal (Specific Aim 1) is to determine the roles of hypothalamic POMC neurons in regulating alcohol reward and drinking behaviors in male and female nPE knockout mice, using drinking-in-the- dark (DID), chronic escalation drinking (CED) and conditioned place preference (CPP) models. The hypothesized reduction by POMC nPE deletion of alcohol behaviors would provide the experimental evidence that hypothalamic POMC neurons are involved in alcohol rewarding or relapse-like drinking, and the conserved POMC nPE enhancers between mice and men could provide a valuable platform for the discovery of transcription factors controlling the POMC expression, and then alcohol drinking. New therapeutic agents may target these transcription factors similarly to what is currently studied for cancer and Parkinson's disease. Our second goal (Specific Aim 2) is in parallel to analyze the hypothalamic POMC expression profiles during alcohol drinking that characterize an underlying mechanism. We will determine if region-specific POMC changes occur in the hypothalamus after DID or CED drinking, or CPP. The study may reveal potentially new molecular mechanisms that provide new insights for understanding the molecular basis of alcohol-related disorders and novel targets for intervention in alcoholism.