THE NEUROANATOMICAL SPECIFICITY OF THE ANXIOLYTIC EFFECTS OF INTRA-SEPTAL INFUSIONS OF MIDAZOLAM

Microinfusions of the benzodiazepine anxiolytic midazolam into the lat eral but not the medial septum suppressed fear reactions in two tests of rat 'anxiety'. Midazolam infusions into the lateral septal nucleiin creased open-arm exploration in the elevated plus-maze test, and block edburying behavior in the shock-probe test, whereas midazolam infusion s into the medial septum produced neither of these anxiolytic effects. The anxiolytic effects of midazolam in the lateral septum were partia lly blocked by pre-infusion of the benzodiazepine receptor antagonist Ro15-1788, which had no intrinsic effects by itself. These results sug gest that the anxiolytic effects of intra-septal midazolam occur, at l east inpart, at GABA(A)-benzodiazepine receptor sites located in the l ateralseptal nuclei.