Temporary improvement in shuttle-box performance of rats after repeated electroconvulsive shock treatment

Abstract

Abstract Studies were conducted to determine the effect of repeated electroconvulsive shock (ECS) treatment on avoidance responding of rats which were poor performers in a two-way shuttle-box. Following 14–20 training sessions, ECS was administered twice daily for 5–8 days. After completion of the ECS treatments, the animals underwent further behavioral testing. The results may be summarized as follows: (1) repeated ECS treatment, without simultaneous training, produced a significant improvement in avoidance responding; (2) the improved performance could not be explained on the basis of spontaneous crossings in the shuttle-box; (3) the improved performance subsided by 72–96 hr after the last ECS; (4) the return to poor performance occurred spontaneously with the passage of time and was not dependent on relearning; (5) α-methyltyrosine pretreatment (50 or 100 mg/kg 2 hr before trials) did not alter the ECS-induced improvement of performance. At least two CNS pathways may be involved in shuttle-box performance, an adrenergic facilitatory system and a cholinergic inhibitory system. An appropriate change in activity (or excitability) of either or both systems could result in an improvement of shuttle-box performance. Although α-methyltyrosine failed to alter the ECS effect, these experiments do not justify elimination of an adrenergic mechanism. This temporary effect of ECS on shuttle-box performance does not involve memory consolidation.