Neuropeptide Y in the central nucleus of the amygdala suppresses dependence-induced increases in alcohol drinking

The anxiolytic effects of neuropeptide Y (NPY) are mediated in part by the central nucleus of the amygdala (CeA), a brain region involved in the regulation of alcohol-drinking behaviors. Centrally administered NPY suppresses alcohol drinking in subpopulations of rats vulnerable to the development of high alcohol-drinking behavior. The purpose of the current study was to determine the role of NPY in the CeA on elevated alcohol drinking produced by alcohol dependence. Adult male Wistar rats were trained to respond for 10% w/v alcohol in an operant situation with the use of a supersaccharin fading procedure. Following stabilization of responding, rats were divided into two groups matched for intake and given daily access to either alcohol-containing (9.2% v/v) liquid diet or an isocaloric control diet. Following extended access to the diet and reliable separation of operant responding between dependent and non-dependent rats during 6-h withdrawal tests, all rats were implanted bilaterally with cannulae aimed at the CeA. Rats were then infused with 4 NPY doses (0.0, 0.25, 0.5, 1.0 microg/0.5 microl aCSF) in a within-subjects Latin-square design during acute withdrawal and tested for operant alcohol responding 30 min later. Alcohol-dependent rats exhibited higher operant alcohol responding than non-dependent rats when infused with vehicle, but responding was similar in the two groups following infusion of all doses of NPY. These results indicate that NPY abolishes dependence-induced elevations in alcohol drinking and implicate the recruitment of limbic NPY systems in the motivational drive to consume alcohol following the transition to dependence.