Selective neurotoxin lesions of the lateral septum: changes in social and aggressive behaviours.

Bilateral microinjection of 5,7-dihydroxytryptamine into the lateral septum resulted in a behavioural profile in the Social Interaction test of anxiety similar to that seen after chronically-administered benzodiazepines. In contrast, bilateral microinjection of 6-hydroxydopamine into this locus did not alter the profile of rats tested in this model. In a colony-intruder model of aggression, the 5,7-dihydroxytryptamine lesioned rats showed decreased dominance, while the 6-hydroxydopamine lesioned rats showed increased dominance and reduced subordination. The results suggest that lateral septal 5-hydroxytryptamine, but not catecholamines, is important in the control of anxiety, whereas both lateral septal 5-hydroxytryptamine and catecholamines are involved in the control of aggression.