Preferences and aversions for stimuli paired with ethanol in hungry rats

Two experiments explored the reinforcing effect of ethanol on conditioned location and flavor preferences in hungry rats. In Experiment 1, rats were administered ethanol (.5, 1.0, or 2.0 g/kg, ig) prior to confinement in one side of a shuttlebox with access to a flavored solution. On control trials, H₂O was administered prior to confinement to the opposite side with a different flavored solution. Location choice tests revealed an overall aversion for the ethanol-associated side that was largest at the 2.0-g/kg dose. Flavor choice tests revealed an aversion for the ethanol-associated flavor at the 2.0-g/kg dose, no reliable difference at the 1.0-g/kg dose, and, of particular interest, a preference at the .5-g/kg dose. The results of Experiment 2 suggest that caloric restoration served as the reinforcing mechanism for the conditioned flavor preference. An isocaloric glucose solution conditioned a flavor preference of the same magnitude as that obtained with ethanol. Moreover, when ethanol provided no caloric advantage, the associated flavor was less preferred than a flavor associated with an isocaloric glucose solution.