Gonadal steroids and aggressive behaviour in male and female rats

Male mice are generally more aggressive than females and experiments suggest that this is due to a differential responsiveness to gonadal hormones. However, no sex differences in testosterone-mediated aggression were apparent in same-sex encounters in two strains of rats. Females mounted each other in these tests far more frequently than did males, indicating that females not only acted as stimuli for activating aggression, but also elicited sexual responses in their partners. Feminine receptivity was infrequently observed in these tests. Organizational effects of gonadal hormones did not appear very important for establishing sex differences in aggression and copulatory behaviour in these animals. The activating effects of steroid hormones upon aggression and sexual behaviour in male and female S3 strain rats are investigated.