Exploration Of Development Changes Of Hippocampal Neurons Microenvironment And Contents Of Amino Acid After Focal Cortical Brain Ischemia In Tree Shrews

Objective: To study changes of hippocampal neuronal microenviro-nment and development alteration of excitatory amino (EAA) and inhibitory amino acid (IAA )in extracellular fluid ( ECF )in different times after thrombotic ischemia in tree shrews, and observe histopathology at 24h after occlusion cerebral thrombosis. Motheds: The focal thrombotic cerebral ischemia was induced by photochemical technology in tree shrews. Hippocampal ECF were collected by microperfusion, and pH, PCO₂,PO₂ and HCO₃ were analysed by blood gas analyzer , and Asp, Glu, Gly and GAB A by high-performance liquid chromatography (HPLC)-PITC technology at 4, 6, 12, 24 and 72 hours after occlusion and contralateral hippocampus at 24h after ischemia. Pathology of bilateral hippocampal neurons was observed. Results: The contents of Asp, Glu, Gly and GABA of hippocampal ECF were increased, and pH, PO₂ and HCO₃^- decreased at 4, 6, 12, 24 and 72h and contralateral at 24h after photochemical induced brain ischemia in tree shrews. There were significant differences between every ishemic and sham, especially Asp,Glu and Gly at 24h, GABA at 72h.and PCO₂ at 6h after occlusion (P<0.01) .At the same time, the pathology of hippocampal neurons were very famous too. Conclusion: Equilibration disturbance of amino acids was either the result of ischemia, or the reason ofsecondary neurons damage and spreading depression after photochemical induced focal cerebral ischemia in tree shrew. Changes of amino acid metabolism were relate to alteration of hippocampal cell microenvironment after occlusion. The changes of contents of amino acids and microenvironment in contralateral hippocampus at 24 hours after ischemia probably were outcome of spreading depression.