Anxiogenic-like effects of yohimbine and idazoxan in two behavioral situations in mice.

In a light-dark choice situation, the alpha-2 adrenoceptor antagonist idazoxan shows anxiogenic-like effects, which cannot be blocked by the alpha-2 adrenoceptor agonist clonidine, or by the benzodiazepine receptor antagonist Ro 15-1788. In a conditioned conflict situation, both idazoxan and the alpha-2-adrenoceptor yohimbine show anxiogenic-like effects; the effect of idazoxan could not be blocked by clonidine or Ro 15-1788. These data suggest that systems other than alpha-2 adrenoceptors or benzodiazepine receptors must be found to explain these anxiogenic-like properties.