Sexual Differences in Behavior Patterns and Hormonal Balance under Normal and Mild Stress Conditions in Inbred Wistar Rats.

Sex differences were studied under normal conditions and after a single mild stress in inbred Wistar rats. It was found that intact females had higher blood corticosterone and leptin levels than males. In females, locomotor activity and the number of active defense reactions in elevated plus maze were higher, while the number of passive defense reactions was lower than in males. After stress, the blood corticosterone and leptin levels increased in both females and males, while the level of the main sex hormones decreased. We found for the first time that leptin and corticosterone levels positively correlated with anxiety index, locomotor activity, and number of active defense reactions and negatively correlated with testosterone and estradiol levels. A hypothesis was put forward that leptin, together with corticosterone, is involved in the organization of the adaptive behavior under stress conditions.