Noninteractive effects of diazepam and amygdaloid lesions in two animal models of anxiety.

The role of the amygdala in mediating the anxiolytic effects of diazepam was examined in two models of rat anxiety. As in our previous experiments, amygdaloid lesions by themselves did not increase rats' exploration of the open arms of the elevated plus-maze or decrease rats' burying of an electrified probe in the shock-probe burying test. However, amygdaloid lesions did increase rats' shock-probe contacts. Diazepam (2 mg/kg) increased open-arm activity and decreased burying behavior to an equal extent in sham-lesioned and amygdala-lesioned rats and had no significant effect on the facilitation of probe contacts induced by amygdaloid lesions. These results suggest that many of the anxiolytic effects of benzodiazepines are not mediated by the amygdala.