Effect Of Mild Hypothermia And Diazepam For Extracellular Amino Acid In A Rat Model Of Global Schemia

Objective Extracellular amino acid including excitatory amino acid and inhibitory amino acid plays a key role in the development of ischemic neuronal injury. It is known that hypothermia and diazepam may be effective for excitatory and inhibitory amino acid; At the same time , a big different neuroprotection is found between pre- and post-ischemic treatment in the clinical and laboratory experience, especial with treatment of hypothermia. Up to now, the effect of pre-ischemic hypothermia is acceptability, but the effect of post-ischemic hypothermia is doubtful. In this study, the two methods of hypothermia and diazepam were employed before and after global ischemia to clarified how extracellular amino acid changed and which morphological appearance was appeared. The objective was to clarified the real effects of hypothermia and diazepam for treatment of global ischemia by modulating excitatory and inhibitory amino acid. And all of above was to improve the clinical effects of cerebral ischemia. METHODS Four vessels method was used to establish the global ischemic model. The temperature of tympan was measured and worked as index of III hypothermia. Mean blood pressure was measured also. Extracellular amino acid was detected by microdialysis in vivo with high performance liquid chromatography. The morphological appearance was observed with stained TIE and TUNEL. The SD rats were divided into such groups: forged operative group; two ischemia groups with normal temperature or non-medicine used; two ischemia groups with pre-ischemic hypothermia or pre-medicine; two ischemia groups with post-ischemic hypothermia or pre-medicine. RESULTS 1. The level of extracellular glutamate and aspartate in groups with normal temperature or non-medicine used was increased obviously after global ischemia compared with the basic level. The level of glutamate is 16 times higher and the level of glutamate is 8 times higher. Serious damaged neurons and a large number of TUNEL-positive neurons were detected in hippocampus. 2. The concentration of the extracellular amino acids in post- hypothermia and post-medicine groups was similar to that in normal temperature group. There were a number of damaged neurons and TUNEL- positive neurons found in hippocampus, but the numbers is fewer than that in normal temperature group. 3. The concentration of extracellular amino acid was much lower than the groups of post-hypothermia and post-medicine. Damaged neurons and TUNEL-positive neurons were much fewer then the groups of post- hypothermia and post-medicine. Iv P CONCLUSIONS 1. To control the concentration of extracellular excitatory amino acid by hypothermia and diazepam provides a therapeutic target for global ischemia. Based on fact that the period is very short for the raising of extracellular excitatory amino acid, the treatment should be used as quick as possible. 2. The neuroprotection of diazepam is from its basic action to enhance Y -amin...