Sex-Related Differences in Anxious-Depressive and Defensive Behavior in Wistar Rats

Sex-related differences in the behavior of animals in aversive situations were identified by comparing male and female Wistar rats in tests for anxiety, depression-like behavior, assessments of the dynamics of the acquisition and extinction of a classical defensive reflex and a passive avoidance reflex, and also acquisition of an active avoidance reflex. In tests for anxiety, females differed from males in having lower levels of anxiety and greater movement and exploratory activity. In the Porsolt test, females showed less extensive signs of depression-like behavior. After stress, the blood corticosterone content in females was greater than that in males. Females showed higher pain sensitivity. Conditioned reflex fear in the passive avoidance reflex was greater in males than females; there was no difference in animals of different sexes in the classical defensive reflex. Extinction of conditioned reflex fear in these two types of reflex occurred more quickly in females than males. Acquisition of the active avoidance reflex was easier in females than males. It is suggested that females are more inclined to the active defensive strategy and to overestimate danger, while males, conversely, prefer passive defensive responses.