Are the anxiogenic effects of yohimbine mediated by its action at benzodiazepine receptors?

Yohimbine, which has activity both at alpha 2-adrenoreceptors and benzodiazepine receptors in the CNS, had an anxiogenic action (1.25-2.5 mg/kg) in the social interaction test in rats. This effect was reversed by the alpha 2-adrenoceptor agonist clonidine (0.01 mg/kg), but not by the benzodiazepine receptor agonist chlordiazepoxide (5-10 mg/kg) or the antagonist Ro 15-1788 (10 mg/kg). These results suggest that the anxiogenic effects of yohimbine are not attributable to its low affinity effects at benzodiazepine receptors but to its alpha 2-adrenoceptor antagonist activity.