Neuropeptide Y suppresses ethanol drinking in ethanol-abstinent, but not non-ethanol-abstinent, Wistar rats.

In outbred rats, increases in brain neuropeptide Y (NPY) activity suppress ethanol consumption in a variety of access conditions, but only following a history of ethanol dependence. NPY reliably suppresses ethanol drinking in alcohol-preferring rats, and this effect is augmented following a period of ethanol abstinence. The purpose of this experiment was to examine the effects of NPY on two-bottle choice ethanol drinking and feeding in Wistar rats that had undergone chronic ethanol vapor exposure, cycles of ethanol abstinence, or both. Ethanol-drinking Wistar rats were given 6 weeks of access to 15% (vol/vol) ethanol and water followed by either: two cycles of 1 week ethanol vapor exposure and 2 weeks with no ethanol; two cycles of 1 week ethanol bottle availability and 2 weeks with no ethanol; or 2 weeks of ethanol vapor exposure. Rats were infused intracerebroventricularly with one of four NPY doses (0.0, 2.5, 5.0, or 10.0 microg) following the ethanol exposure patterns described above, and tested for ethanol drinking and feeding in a two-bottle choice situation. NPY dose dependently increased food intake regardless of ethanol exposure history, but suppressed ethanol drinking only in rats that underwent cycles of ethanol access and ethanol abstinence. These results support the notion that dysregulation of brain NPY systems during chronic intermittent ethanol exposure is important in the motivational drive for subsequent relapse to ethanol drinking.