The impaired coping induced by early deprivation is reversed by chronic fluoxetine treatment in adult fischer rats.

The symptoms of depression include feelings of reduced coping ability and increased helplessness. Early life adversity increases vulnerability to depression. In rats, the quantification of ability to cope with adverse challenge can be achieved using preexposure to an inescapable aversive stimulus and subsequent assessment of escape or avoidance deficits in the same environment. Here we investigated the predictive validity of a model in which, in the Fischer rat strain, postnatal isolation leads in adulthood to a state of increased sensitivity to develop an escape or avoidance deficit. On days 1-14 rat pups were isolated for 4 hours (early deprivation, ED) or for 15 minutes (early handling, EH), or were left completely undisturbed (non-handling, NH). In adulthood, subjects were placed in a shuttle box and half were exposed to brief, mild foot shocks (preexposure, PE) and the other half were non-preexposed (NPE). Half of the PE and NPE subjects were then treated for 21 days with fluoxetine and the other half with vehicle. In males, although there was no overall preexposure effect on avoidance behaviour, ED-PE and ED-NPE and EH-PE and EH-NPE demonstrated an avoidance deficit relative to NH. Fluoxetine attenuated this deficit and most notably in ED-PE. In females, vehicle ED-PE demonstrated an avoidance deficit relative to NH-PE; fluoxetine attenuated this ED effect. These findings provide supportive evidence for the predictive validity of this depression model.