Lateral Septum Influences on the Emotional Sequelae Induced by Psychosocial Stress: Modulation by Corticosterone

CALFA G, VOLOSIN M

Los Cocos

Congreso; XVII NATIONAL MEETING OF THE ARGENTINE SOCIETY FOR NEUROCHEMISTRY; 2002

Sociedad Argentina de Neuroquimica

Psychosocial stressor exposure produced a decrease of locomotor activity in an open field test 20 h after  the confrontation. The i.c.v. administration of glucocorticoids-receptor antagonists MR (A-MR) or GR (A-GR) before stress normalized this response in supine animals (S), but not in no-supine animals (N-S). Objective: Considering that Lateral Septum (LS) plays a role in the attenuation of an aversive state and coexpresses GR and MR, in this work we analyzed the involvement of LS and corticosterone on the emotional consequences induced by social defeat. Methods: The resident-intruder paradigm was used. Male rats bilaterally cannulated in LS were confronted to an aggressive resident and 20 h later evaluated in an elevated plus-maze test (EPM). A-MR (RU28318, 10 ng per 0.4 μL) or A-GR (RU38486, 10 ng per 0.4 μL) were infused before confrontation. Results: S and N-S rats showed a decrease in the percentage of time spent in open arms when compared to controls. A-GR infusion reverted this effect in both S and N-S, whereas there was no effect in A-MR-infused animals. Agonistic interaction during confrontation, locomotor activity, and other anxiety-like behaviors were not modified by antagonist infusions. Conclusion: A unique session of psychosocial stress produced a long-lasting effect on the emotional response evaluated in this animal model of anxiety. The response was independent of the coping behaviors during deagonistic interaction (S or N-S). Only LSeptum A-GR-infused animals normalized the anxiogenic consequences in S and N-S. Thus, CS secretion during the confrontation could play a role—via GR—in LS, facilitating anxiety-related behaviors.