代谢性谷氨酸受体配体参与大鼠海马脑缺血耐受诱导机制的研究

Effects of the metabotropic glutamate receptor ligands on the induction of brain ischemic tolerance in rats

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CAl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 receptor(mGluR) is Gprotein coupled membrane receptors,which participate in various physiology or pathology process in brain,but how it induce brain ischemic tolerance(BIT) is unclear.OBJECTIVE:To study roles of mGluR2/3 and mGluR1/5 in the BIT induction.DESIGN:Randomized controlled study based on experimental animals.SETTING:Neurological department of provincial hospital and pathophysiological department of basic institute in a university.MATERIALS:The study was conducted at the Pathophysiological Department,Institute of Basic Medicine,Hebei Medical University from May 2002 to May 2003.Totally 64 healthy male SD rats were selected from the Experimental Animal Center of Hebei Medical University.Glial fibrillary acidic protein(GFAP) antibody,MTPG and(s)4C3HPG were got from Sigma Company.INTERVENTIONS:4 vessel occlusion(4VO) brain ischemic models in rats stained with thionine staining and GFAP immunohistochemistry staining.were used.Sixtyfour rats,of which bilateral vertebral arteries were occluded permanently by electrocautery,were divided into the following 8 groups:sham operation group,cerebral ischemic preconditioning(CIP) group,ischemic insult group;BIT group;MTPG+sham operation group;MTPG+BIT group;MTPG+ischemia group and(s)4C3HPG+BIT group.All the rats were killed 7 days after the operation or the final ischemic treatment.Cerebral sections were selected and stained with thionine staining and GFAP immunohistochemistry staining.MAIN OUTCOME MEASURE:The changes of the morphologic hippocampal pyramidal cell and GFAP expression of astrocyte.RESULTS:①The 8 minutes ischemic insult increased the histological grade(HG) in CA1 area,decreased the pyramidal neuronal density(ND) and increased the expression of GFAP significantly(P< 0.05).②The above changes were not observed in the BIT group,indicating that the CIP could protect pyramidal neurons against the 8minute ischemic insult.③The protective effects of the CIP were blocked by MTPG or(s)4C3HPG,as manifested by significant increases in HG and decreases in ND in the groups of MTPG+BIT,MTPG+ischemia and(s)4C3HPG+BIT(P< 0.05).CONCLUSION:MTPG or (s)4C3HPG could block the induction of BIT induced by CIP,but mGluR2/3 or mGluR1/5 could participate in the induction of BIT by which protect effect of mGluR is further induced.