Exposure to novel environmental stimuli decreases amphetamine self-administration in rats

Researchers examined whether exposure to novel environmental stimuli reduces drug self-administration. Rats were trained to self-administer amphetamine on a fixed ratio (FR) 5 schedule of reinforcement and then were exposed to novel stimuli during the session. Responding was significantly decreased with exposure to novelty but returned to baseline levels on intervening nonexposure sessions. In 2 subsequent experiments, rats were exposed to novel plastic objects prior to the session. Immediately following exposure, rats were allowed to self-administer amphetamine on an FR 1 schedule, which was increased gradually to an FR 5 either using predetermined increments or on the basis of performance criteria. Exposure to the novel objects significantly decreased acquisition of amphetamine self-administration in both situations. Results suggest that exposure to novel environmental stimuli may be effective at reducing drug self-administration.