Effects of fluoxetine on behavioral deficits evoked by chronic social stress in rats.

Recently, we described an advanced model of chronic social stress in male rats based on the resident intruder paradigm. In this model, rats subjected to daily social stress for 5 weeks showed behavioral changes resembling anhedonia and motivational deficits in humans. In the present study, male Wistar rats were subjected to 5 weeks of daily social defeat by an aggressive conspecific and concomitant treatment with the antidepressant drug fluoxetine (10 mg/kg) after the first week of stress. Compared with controls, rats exposed to chronic stress had significantly reduced locomotor and exploratory activity (rearing and sniffing) and diminished preference for sucrose solution. These effects were paralleled by decreased body weight gain, increased adrenal weights and decreased plasma levels of testosterone measured post mortem. The stress-induced effects on locomotor activity and rearing behavior were counteracted by fluoxetine treatment.