Citalopram abolishes depressive-like symptoms evoked by chronic social stress in rats

Objectives: Recently we described a model of chronic social stress in rats, based on the resident intruder paradigm. In this model rats subjected to daily subordination stress for a period of 5 weeks showed behavioural changes being considered as behavioural correlates of depressive-like symptoms, such as anhedonia and motivational deficits (Rygula et al Behav Brain Res 2005). The present study was done to pharmacologically validate this chronic social stress model in rats as a model of depressive like symptoms.

Methods: Rats were socially stressed as described previously and in parallel subjected to chronic (4 weeks) treatment with the SSRI citalopram. The drug was administered orally in drinking water (40mg/kg/day). In a pilot study the optimal dose of citalopram for oral administration was determined. The effects of chronic social stress and citalopram treatment were assessed in a battery of behavioural tests including open field, sucrose preference and forced swimming.

Results and conclusion: Chronic oral administration of citalopram abolished all adverse effects of chronic social stress in the behavioural tests mentioned, by causing normalisation of behaviours related to motivation and reward sensitivity. These observations provide the first proof for the predictive validity and support the present model of chronic psychosocial stress as a model of depressive-like symptoms in rats.