Aggressive behaviour in rats: Effects of winning or losing on subsequent aggressive interactions.

CPB-WE rats (WEzobs) tested for aggression against Tryon Maze Dull rats (S3s) were highly consistently defeated. In contrast, when tested against Wistars, these WEzobs become dominant. On the basis of these findings an experimental procedure was used in which the changes in agonistic responses as the result of experience of victory or defeat could be established. In addition, the effect of winning or losing was studied in subsequent encounters of winners and defeated WEzobs. The result of this experiment clearly indicate that a significant and relatively permanent behavioural inhibition develops in the defeated WEzobs which show less social initiative and aggression than the winners. The behavioural inhibition which is also seen in the spatial orientation of the animals within the test arena was still present after a 14 day interval. Significant loss of body weight was found in the losing animals.