THE CENTRAL AND BASOLATERAL AMYGDALA DIFFERENTIAL MEDIATE THE ANXIOLYTIC EFFECTS OF BENZODIAZEPINES

Microinfusions of the benzodiazepine anxiolytic midazolam into the cen tral or basolateral amygdaloid nuclei produced different anxiolytic ef fects in two tests of rat 'anxiety'. Infusions into the basolateral nu cleus impaired open-arm avoidance in the elevated plus-maze test, but did not impair shock-probe avoidance in the shock-probe burying test. In contrast, infusions into the central nucleus impaired shock-probe a voidance, but did not impair open-arm avoidance. Both of these site-sp ecific, midazolam-induced anxiolytic effects were blocked by a pre-inf usion of the benzodiazepine receptor antagonist Ro 15-1788 (flumazenil ). None of the treatments affected defensive burying. These results su ggest that benzodiazepine receptors in the central and basolateral amy gdaloid nuclei differentially mediate the anti-anxiety effects of benz odiazepine anxiolytics.