Anxiolytics antagonize yohimbine's discriminative stimulus properties.

Male Sprague-Dawley rats were trained to discriminate 3.2 mg/kg yohimbine HCl from saline in a two-lever operant procedure. Generalization tests indicated that piperoxane, another alpha 2-adrenergic blocker with anxiogenic properties in humans, produces yohimbine-like discriminati-effects.. In contrast to yohimbine and piperoxane, many other agents were discriminated as vehicle, including corynanthine, raubasine, phentolamine, prazosin, WB-4101, mianserin, tolazoline, and mezilamine. Diazepam caused a dose-related antagonism of yohimbine's stimulus properties. A partial antagonism of yohimbine cueing was also obtained with meprobamate, phenobarbital, chlordiazepoxide, and clonazepam. These results suggest that yohimbine discrimination in rats may be a useful model for detecting agents with anxiolytic activity.