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背景:代谢型谷氨酸受体是G蛋白偶联的膜受体,参与脑内多种生理、病理过程,但其参与脑缺血耐受的诱导机制尚不清楚。目的:探讨代谢型谷氨酸受体2/3、代谢型谷氨酸受体1/5在脑缺血耐受诱导中的作用。设计:以动物为研究对象,随机对照实验。单位:一所省级医院的神经科和一所大学的基础研究所病理生理学研究室。材料:实验于2002-05/2003-05在河北医科大学基础医学研究所病理生理研究室完成。健康雄性SpragueDawley大鼠64只由河北医科大学实验动物中心提供。试剂胶质纤维酸性蛋白抗体、MTPG和(s)-4C3HPG均购自Sigma公司。干预:采用大鼠四血管闭塞全脑缺血模型,应用硫堇染色和胶质纤维酸性蛋白免疫组化法。64只大鼠椎动脉凝闭后分为假手术组、单纯预处理组、单纯缺血组、脑缺血耐受组,MTPG+假手术组、MTPG+脑缺血耐受组、MTPG+缺血组和(s)-4C3HPG+脑缺血耐受组,所有动物均在手术后或末次缺血后7d处死取材,行脑组织切片,硫堇染色和胶质纤维酸性蛋白免疫组化染色。主要观察指标:观察海马锥体细胞形态学变化及星形胶质细胞胶质纤维酸性蛋白表达的变化。结果:①单纯8min缺血可使海马CA1区组织学分级升高、锥体神经元密度降低和胶质纤维酸性蛋白阳性表达增加(P<0.05)。②脑缺血耐受组未见单纯缺血组的上述变化,表明脑缺血预处理可防止后续8min缺血造成的神经元损伤。③脑缺血预处理的这种保护作用可被MTPG或(s)-4C3HPG阻断,表现为海马CA1区组织学分级升高和锥体神经元密度降低(P<0.05)。结论:MTPG或(s)-4C3HPG可阻断脑缺血预处理诱导脑缺血耐受的作用,提示代谢型谷氨酸受体2/3,代谢型谷氨酸受体1/5参与脑缺血耐受的诱导,揭示了其对神经损伤保护作用的机制。
BACKGROUND: Metabotropic glutamate receptors are G protein-coupled membrane receptors that are involved in various physiological and pathological processes in the brain. However, the mechanism of their involvement in cerebral ischemic tolerance remains unclear. Objective: To investigate the role of metabotropic glutamate receptor 2/3 and metabotropic glutamate receptor 1/5 in inducing cerebral ischemic tolerance. Design: Animals as research subjects, randomized controlled trials. Unit: Department of Neurology at a Provincial Hospital and Pathophysiology Laboratory at the Institute of Basic Research of a University. Materials: The experiment was performed at the Pathophysiology Laboratory of Institute of Basic Medical Sciences, Hebei Medical University from May 2002 to May 2003. Sixty-four healthy male Sprague Dawley rats were provided by Experimental Animal Center of Hebei Medical University. Reagents Glial fibrillary acidic protein antibodies, MTPG and (s) -4C3HPG were purchased from Sigma. Intervention: Rat model of global cerebral ischemia occlusion was established. Thionine staining and glial fibrillary acidic protein immunohistochemistry were used. Sixty-four rats were randomly divided into sham operation group, simple preconditioning group, simple ischemic group, cerebral ischemic tolerance group, MTPG + sham operation group, MTPG + ischemic tolerance group, MTPG + ischemia group and (s) -4C3HPG + cerebral ischemic tolerance group, all animals were sacrificed 7d after the operation or the last ischemia, brain sections, thionine staining and glial fibrillary acidic protein immunohistochemical staining. MAIN OUTCOME MEASURES: Morphological changes of hippocampal pyramidal cells and changes of glial fibrillary acidic protein expression were observed. Results: ①After 8min ischemia, hippocampal CA1 area increased histological grade, decreased pyramidal neuron density and glial fibrillary acidic protein positive expression (P <0.05). ② There was no change in the ischemic group, indicating that cerebral ischemic preconditioning could prevent neuronal damage caused by the subsequent 8min ischemia. (3) This protective effect of cerebral ischemic preconditioning can be blocked by MTPG or (s) -4C3HPG, and the histological grade and the density of pyramidal neurons in hippocampal CA1 area were decreased (P <0.05). CONCLUSION: MTPG or (s) -4C3HPG can block the induction of cerebral ischemic tolerance induced by ischemic preconditioning, suggesting that metabotropic glutamate receptors 2/3 and metabotropic glutamate receptors 1/5 participate in brain Induction of ischemic tolerance reveals its protective effect on nerve injury mechanism.