Impulsive Action, Psychological Stress, and Behavioral Sensitization to Nicotine in a Rat Model of lmpulsivity

Abstract : Impulsivity, a construct characterized by immediate action without consideration of future consequences, is associated with cigarette smoking. Psychological stress increases cigarette smoking, and this effect may be augmented in impulsive individuals. Increased nicotine reinforcement under stress and in impulsive individuals may underlie relationships among the variables. The effect of stress on impulsive action and reinforcing actions of nicotine, and whether such effects differ in impulsive and non-impulsive individuals, is not known. The present research examined effects of stress on impulsive action, attention, and nicotine behavioral sensitization in Lewis (impulsive) and Fischer (non-impulsive) rats. Subjects were 32 male Lewis and Fischer rats used in a 2 (Lewis, Fischer)x 2 (stress, non-stress) factorial design with repeated measures. The research was divided into two conceptually distinct experiments using the same subjects. In Experiment 1, rats' impulsive action and attention were measured in the Five Choice Serial Reaction Time Task (5-CSRTT), and their locomotor activity was measured in locomotor activity chambers. In Experiment 2, rats' locomotor activity was measured daily immediately after they received injections of 0.5mg/kg nicotine. Rats also were tested in the 5-CSRTT in Experiment 2, after locomotor activity was measured.