Buspirone fails to affect the discriminative stimulus effects of cocaine.

Rats were trained to discriminate 4.0 mg/kg cocaine from saline in a two-lever, food-reinforced drug discrimination paradigm. Cocaine (0.5-8.0 mg/kg, IP) produced a dose-related increase in cocaine-appropriate responding, with the training dose of 4.0 mg/kg being the lowest dose that met criterion (> 90% cocaine-appropriate responding over the entire session) for substitution. Pretreatment with buspirone (2.0-16 mg/kg, IP) did not attenuate the discriminative stimulus properties of 4.0 mg/kg cocaine at doses up to those that caused complete suppression of responding (16 mg/kg, IP). In contrast, combinations of 0.12 mg/kg haloperidol with 4.0 mg/kg cocaine decreased cocaine-appropriate responding from 100 to 65% while suppressing response rate to 50% of the response rate seen with the 4.0-mg/kg dose of cocaine alone. Thus, behaviorally active doses of buspirone failed to attenuate the discriminative stimulus effects of cocaine in a sensitive behavioral paradigm.