Comparison of Several Aggression Models in Long-Evans (Hooded) Rats: Effects of Sex and Isolation

Abstract

Several experiments were conducted in which “free-cage” aggression, “shock-elicited” aggression, and “mouse-attack” were examined in Long-Evans hooded rats. It was found that the pattern of agonistic postures differed for different models of aggression. In the free-cage situation females exhibited more defensive posturing than did males, whereas males showed more biting and attack behavior than did females; both males and females exhibited mouse attack. In the shock-aggression situation males showed higher frequencies of all aggressive behaviors than did females. Animals which lived in pairs tended to show less agonistic posturing in all three models than did animals which lived alone. These findings suggest that different aggression models assess different aspects of agonistic behavior, and moreover that “attack” vs “defense” can be reliably differentiated in the laboratory rat.