Behavioral consequences of chronic stress and effects of antidepressant treatment on animal models of depression

Major depression has a high prevalence and a high mortality. In order to understand the molecular changes underlying major depression animal models are needed. The different animal models of depression simulate the etiology and replicates symptoms, course and treatment of human depression properly. In this study, we investigated stress-induced depressogenic induction among the rats using Shuttle Box Escape Test, Open Field Test (OFT) and Elevated Plus Maze (EPM) Test. Fluoxetine hydrochloride (FLX), an antidepressant was administered chronically to determine antidepressant mediated recovery of their behavioral homeostasis. In addition, all the behavioral tests demonstrated a variety of specific symptoms like changes in locomotor activity, impaired learning ability and cognition deficit etc. From these findings, we can conclude that chronic inescapable foot-shocks at 0.8mA intensity for 15 sec duration are the most effective stressor to produce animal model of depression. After exposure to chronic foot-shocks, FLX mediated recovery strengthen our findings. In addition, the rats were screened through shuttle box escape test that mimic depressive-like behavior properly in animals. Our observation clearly corroborates well with the learned helplessness (LH) paradigm. So, the animal models of depression using electric foot-shock to induce depressive like behavior, have excellent face validity and replicate anhedonia and anergia in analogy to loss of interest and pleasure.