Effects of prior exposure to cocaine: interaction of reinforcing and suppressant effects.

Squirrel monkeys were trained to respond under second-order schedules of food presentation and then sequentially exposed to either a self-administration (SA) and then a conditioned taste aversion (CTA) procedure, or a CTA procedure and then a SA procedure. Initial exposure to stimuli associated with post-session delivery of cocaine (0.3 mg/kg) either maintained (SA) or suppressed (CTA) responding, respectively. In contrast, following exposure to CTA, SA procedures failed to maintain levels of responding comparable to those seen with initial exposure to SA. Following exposure to SA, the CTA procedure failed to suppress responding. Thus, prior exposure to either the reinforcing or suppressant effects of cocaine modified its subsequent behavioral effects, suggesting a unique role for behavioral history in the abuse potential of cocaine.