Neuropeptide Y (NPY) is abundant in the mammalian brain and plays a prominent role in behaviors related to negative affect and alcohol. NPY suppresses anxiety-like behavior and alcohol-drinking behaviors in a wide array of rodent models and also affects changes in these behaviors produced by fearful and stressful stimuli. Rats selectively bred for high alcohol preference (P rats) appear to be particularly sensitive to the behavioral effects of NPY. The dual purpose of the present investigation was to determine the effects of intraventricular NPY on (1) the acoustic startle response (ASR) of P rats in a high-anxiety setting and (2) social interaction behavior of P rats. In experiment 1, P rats were either cycled through periods of long-term ethanol access and abstinence or they remained ethanol naive. Rats were injected with one of four NPY doses and tested for ASR before and after footshock stress. NPY suppressed ASR in all P rats regardless of shock condition or drinking history. In experiment 2, rats received intraventricular infusion of one of four NPY doses and were then injected with either ethanol (0.75 g/kg) or saline and tested for social interaction. NPY increased social interaction in P rats even at doses that suppressed locomotor activity, regardless of ethanol dose. Suppression of anxiety-like and arousal behaviors by NPY in the present study confirm a role for NPY in alcohol-related behaviors in alcohol-preferring P rats.
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