[Dynamics of extracellular acetylcholine of the gerbil striatum during cerebral ischemia monitored by intracerebral microdialysis].

Neurons in the hippocampus and striatum are vulnerable to the ischemic insult. In the present study we focused on the vulnerability of acetylcholine (ACh)-containing neurons in the striatum. To determine the change of ACh content in the striatum, we employed a simple sensitive brain microdialysis method with high performance liquid chromatography electrochemical detection. Morphological change of cholinergic neurons was studied by ACh-esterase staining during ischemic insult. After bilateral carotid artery occlusion, local cerebral flow decreased less than 5 ml/min/100 g in the striatum. Ach content in dialysate for 20 min after the occlusion was elevated to 135% of the control. ACh content decreased to 15% of the control 2hs after the ischemia. Density of Cholinergic fibers and cell bodies was reduced 10 min after the ischemia and further decreased 20 min after the occlusion. Our study suggests that the transient elevation of ACh content was probably due to diffusion of ACh from destruction cholinergic terminals after the ischemic insult. The increase of ACh immediately after arterial occlusion may affect severity of ischemic damage in the brain by its excitatory effect.