HORMONAL AND METABOLIC RESPONSES DURING PSYCHOSOCIAL STIMULATION IN AGGRESSIVE AND NONAGGRESSIVE RATS

The physiological effects of a psychosocial threat (the mere presence of a potentially antagonist individual in the home cage) were studied in aggressive and nonaggressive rats. Aggressive animals spent a signi ficantly longer time with the investigation of the opponent compared w ith the nonaggressive group. An increase in plasma epinephrine and cor ticosterone was noticed both in aggressive and nonaggressive animals. Ir beta-endorphin increased significantly only in nonfighters. Glycemi a was slightly larger in nonaggressives, while lactaemia increased in both groups. The possibility is discussed that differences in psychoso cial stress response may be involved in the regulation of behavior in a real encounter.