Effects of agonistic experience in rats

Relatively little attention has been paid to the effects of agonistic experience upon subsequent behaviour in rodents. Some studies in mice and rats indicate that winning or losing may drastically alter behaviour in subsequent encounters, especially the losers who show a marked inhibition of fighting and motor activity. The authors recently developed in their laboratory a procedure for inducing winning or losing in WEzob strain rats. This paradigm was based upon the finding that when tested against S3 (TMD) rats, WEzobs were always defeated relatively quickly, whereas when tested against Wistar rats, WEzobs were more aggressive and generally became dominant. After three daily confrontations with either a S3 or a Wistar rat (induction phase), WEzob losers were confronted with Wezob winners on a fourth day and retested after a period of 14 days (test phase). All tests lasted 30 minutes and analysis of variance was used to compare behavioural changes throughout tests (in blocks of 10 minutes) and over days.