Specific antagonism of the behavioral effects of chlordiazepoxide and pentobarbital in the rat.

Stimulus control was established in rats with 5 mg/kg chlordiazepoxide and saline by employing a two-lever response choice task and an FR10 schedule of food reinforcement. Once trained, administration of chlordiazepoxide doses different from the training dose produced dose-responsive discrimination responding and the chlordiazepoxide discriminative cue was observed to transfer to pentobarbital. Pretreatment with the convulsant bemegride antagonized the pentobarbital transfer but not the chlordiazepoxide cue, whereas the specific benzodiazepine antagonist RO15-1788 decreased the chlordiazepoxide cue in a dose-response manner without attenuating the pentobarbital transfer. Results confirm and expand upon other recent studies that suggest different mechanisms of action for chlordiazepoxide and pentobarbital.