SEPTAL-LESIONS INHIBIT FEAR REACTIONS IN 2 ANIMAL-MODELS OF ANXIOLYTIC DRUG-ACTION

The role of the septum in anxiety was studied using two different animal models of antianxiety drug action; i.e., the shock probe-burying test and the clevated plus maze test. Antianxiety effects were observed in both paradigms (i.e., a decrease in probe burying, and an increase in open arm activity) after lesions of the entire septum, compared to sham-lesioned controls (Experiment 1). No differences between lesioned and sham-lesioned rats were found in general activity, shock reactivity, or handling reactivity at the time of the antianxiety tests. A second experiment showed that the antianxiety effects observed in the two paradigms were anatomically specific, since lesions of the posterior septum decreased both indices of anxiety (probe burying and open arm avoidance), whereas lesions of the anterior septum resulted in levels of anxiety that were comparable to those displayed by sham-lesioned controls. Taken together, these results provide convergent evidence that posterior regions of the septum play an important role in the control of anxiety in the rat. © 1990.