The effect of electroconvulsive shock on learning and memory in rats

Acetylcholinesterase activity in regions of rat brain following repeated administration of electroconvulsive shock

It has previously been shown that 30 min after administration of a single elec troconvulsive shock (ECS) to rats there is a marked decrease in both soluble and total acetylcholinesterase (AChE) activity in the midbrain and hippocampus. In the current study it has been shown that AChE activity is unchanged in these regions (apart from a small rise in soluble AChE in the hippocampus) 30 min after the final ECS of a series of 10 (once daily for 10 days). Twenty-four hours after the last ECS there was a significant increase in total and membrane bound AChE activity in the striatum but not hippocampus, midbrain, cortex and amygdala. This change in the striatum may be associated with the change in GABA synthesis which has been shown to also occur in this region at the same time.

Acetylcholinesterase activity in regions of the rat brain following a convulsion

The effects of electroconvulsive shock on the levels of acetylcholinesterase in several brain regions of the rat were studied. Hippocampus, mesencephalon, cortex, and striatum exhibited rapid changes in acetylcholinesterase activity during the first few minutes following the convulsion, whereas brainstem and basal forebrain levels remained unchanged. In both hippocampus and midbrain there was a sustained decrease in activity: the total acetylcholinesterase activity was decreased by up to 40% within 2 min of the convulsion and did not return to control values for another 3 h. Thirty minutes after a flurothyl-induced convulsion there was a similar fall in acetylcholinesterase activity in both these regions, whereas a subconvulsive electric shock produced no change. It is concluded that a convulsion produces significant short-term decreases in acetylcholinesterase activity in areas of the rat brain that are involved in the generation and propagation of seizures, and the question is raised of whether this is related to the increase in seizure threshold that follows a convulsion.