Change of Leu-enkephalin- and B-endorphin-like immunoreactivity in the hippocampus after electroconvulsive shock and electroacupuncture

To determine whether the effect of electroacupuncture (EA) on electroconvulsive shock (ECS) was through affecting endogenous opioid peptidergic system in the hippocampus, we used radioimmunoassay (RIA) to measure leu-enkephalin- and beta-endorphin-like immunoreactivity (L-E-LI and Beta-E-LI) in the hippocampal perfusate after ECS and EA treatments. Wistar rats were given ECS stimulation, which caused behavioral and electroencephalogram (EEG) convulsions. However, EA could suppress ECS-elicited convulsions (including both behavioral and EEG abnormalities). The results of RIA showed that after repeated ECS treatments, the contents of L-E-LI and Beta-E-LI increased significantly by 136% and 157%, respectively. In contrast, EA treatment depleted alterations of L-E-LI and Beta-E-LI induced by ECS, depleting L-E-LI by 32% and Beta-E-LI by 85%. These observations suggest that anticonvulsive action of EA is related to the release of L-E and Beta-E in hippocampus, probably through decreasing their release, thus to exert EA action.