Effects of intrahippocampal delta-receptors on inhibition of electroconvulsive shock by electro-acupuncture

The relationship between the delta-receptors of the hippocampus and electro-acupuncture (EA) anticonvulsions was analyzed by radioimmunoassay and microinjection. The content of leu-enkephalin-like immunoreactive substance (LEK-LIS) in perfusate from the hippocampus increased after repeated electroconvulsive shock (ECS), while the content of LEK-LIS was not changed after single ECS. EA inhibited epileptiform spikes induced by ECS, and the content of LEK-LIS decreased markedly after EA (30 +/- 9 pg/0.1 ml lower than that before EA). Leu-enkephalin (LEK), an agonist of the delta-receptors, 10 micrograms injected into the hippocampus produced epileptiform spikes. However, ICI 174,864 (4 micrograms), a specific antagonist of the delta-receptors, suppressed convulsions significantly. The results suggest that the delta-receptors of the hippocampus participate in EA anticonvulsions.