Comparison of the Alcohol-Preferring P Rat to the Wistar Rat in Behavioral Tests of Impulsivity and Anxiety

M cMillen, B. A., L. W. Means, J. Matthews. Comparison of the alcohol-preferring P rat to the Wistar rat in behavioral tests of impulsivity and anxiety. PHYSIOL BEHAV 63(3) 371–375, 1998.—To determine whether the selectively bred alcohol preferring P rat displays impulsive and anxiety-related behaviors, as have been noted in Type 2 human alcoholics, P rats were compared with outbred Wistar rats, the strain from which P rats were derived, on a series of behaviors reflecting impulsivity and anxiety. The two groups were also compared on their volitional consumption of ethanol. When compared with the Wistar rats, the P rats preferred a higher concentration of ethanol and imbibed a much greater amount of ethanol when they were offered their preferred concentration. However, the behavioral tasks produced inconsistent results. The P rats completed 100 bar presses for food in less time when tested on a constant reinforcement schedule, which suggests that they are hyperactive compared to Wistar rats. However, the P rats also emitted a higher percentage of reinforced responses on differential reinforcement of low rate responding (DRL)-10s and gnawed less from a cork stopper, which suggests that they are less impulsive and possibly neophobic. The two groups did not differ on emergence into or activity in an open field, their activity in or open-arm duration in the elevated plus maze, or performance on DRL-5s and DRL-15s. Collectively, the behavioral data suggest that P rat does not serve as a model for the anxiety and impulsiveness associated with the Type 2 alcoholic individual.