Defeat followed by individual housing results in long-term impaired reward- and cognition-related behaviours in rats

In contrast to the well-documented acute effects on behavioural sensitivity , chronic effects that persist for weeks or even months after the cessation of the stressor received relatively little attention. This study aimed at the long-term effects of a severe stressor, i.e. social defeat followed by individual housing. Defeated and subsequently individually housed animals d isplayed impaired social memory, decreased social interaction and diminishe d anticipation for a sucrose solution for up until a period of 3 months aft er defeat. Remarkably, social housing counteracted the defeat-induced effec ts. The impaired capability to anticipate for a reward was discussed in rel ation to anhedonia, an important symptom of human depression. Moreover, the disturbed memory, the chronic nature of the effects, and the therapeutic e ffects of social housing, suggest that the defeat model may serve as a pote ntial model for human psychopathology. (C) 2000 Elsevier Science B.V. All r ights reserved.