[Agonistic behavior during stress inhibits the development of learned helplessness in rats].

Male Wistar rats were exposed to inescapable shock in individual chambers (IS), or shocked in pairs (PIS). The latter rats were fighting during the shock administration. In 48 hrs, all the rats were subjected to escape/avoidance task in a shuttle-box. Failures increased significantly in the IS rats as compared with the PIS and intact rats. Dexamethasone administration decreased the plasma corticosterone level in the latter groups, but not in the IS rats. The findings suggest that an inescapable shock induces no learned helplessness in rats having an opportunity of agonistic interaction during the shock. The findings suggest also a stress-protective effect of agonistic contacts under averse conditions.