The effect of repeated electroconvulsive shock on avoidance conditioning and brain monoamine oxidase activity

Brain monoamine oxidase activity was elevated throughout the brain after 42 daily ECS and remained so up to 19 days after the last treatment without any accompanying changes in protein concentration or the activities of succinate dehydrogenase or catechol O-methyl transferase.

Abstract

The primary purpose of these experiments was to examine the effect of repeated electroconvulsive shock (ECS) on avoidance conditioning in male Fischer rats. ECS-treated rats generally made more conditioned avoidance responses (CARs) than controls after 7, 14, or 42 treatments during acquisition to either tone or light and during subsequent transfer of the CAR to the other modality. This occurred despite the fact that the pretrained escape response was partially lost by the ECS-treated rats as a function of the number of treatments. Intertrial response rates were also increased by repeated ECS when tone, but not light, was the initial conditioned stimulus and during cross-modal transfer to both tone and light. The results are interpreted as reflecting an increased sensitivity and/or responsivity to aversive stimulation caused by repeated ECS. A second purpose was to verify the persisting increase in brain monoamine oxidase activity observed earlier [15] to follow repeated ECS. The activity of this enzyme was elevated throughout the brain after 42 daily ECS and remained so up to 19 days after the last treatment without any accompanying changes in protein concentration or the activities of succinate dehydrogenase or catechol O-methyl transferase.