Decrease in stress-induced c-Fos-like immunoreactivity in the lateral septal nucleus of learned helpless rats

Inescapable stress can induce learned helplessness in many species of anima ls. Learned helplessness is a phenomenon which has some behavioral and neur otransmitter analogies with human clinical depression. Stress can also indu ce the expression of immediate early genes, including c-fos in many areas o f the central nervous system. We examined stress-induced c-Fos-like immunor eactivity (FLI) using the learned helplessness paradigm. Naive mts showed s ignificantly higher FLI than the tested groups in all the amygdaloid region s and in the hypothalamic paraventricular nucleus. However, in the lateral septal nucleus, helpless animals showed significantly reduced FLI in respon se to stress, compared to the other groups. These, and other previous data, highlight the importance of the septal area in mediating behavioral respon ses to inescapable stress. (C) 1999 Elsevier Science B.V. All rights reserv ed.