Exposure to the stressor environment prevents the temporal dissipation of behavioral depression/learned helplessness

Background: Exposure to uncontrollable stressors such as inescapable shock (IS) produces a set of behavioral changes such as poor escape teaming that have been called behavioral depression and learned helplessness. This parad igm has been proposed to be a model of depression and anxiety-related disor ders,such as post-traumatic stress disorder (PTSD). However, the behavioral changes persist for only a few days after the stressor; rendering the phen omenon questionable as a model. However tire original traumatic experience is re-experienced in PTSD and I rumination occurs in depression. In a serie s of experiments Mle therefore sought to determine whether behavioral depre ssion/learned helplessness could De made to endure by periodically "remindi ng" the subject of the original IS experience. Methods: Rats exposed to IS were tested for escape learning at various time s thereafter In different experiments the subjects were exposed to the envi ronment in,which IS had occurred at differing points in the interval betwee n IS and escape testing. Results: Exposure to the environment in which IS had occurred prolonged the duration of behavioral depression/learned helplessness, and repeated expos ures prolonged it indefinitely This effect required exposure to the cues th at had been present during IS (i.e,, reminding) and was not duplicated by e xposure to other stressors or stress environments. Conclusions: Behavioral depression/learned helplessness can be maintained o ver time by processes that may be similar to those occurring in depression and PTSD, thereby strengthening the possibility that this paradigm is indee d a reasonable model of these disorders. (C) 2001 Society of Biological Psy chiatry.