NMDA受体拮抗剂MK-801对缺氧缺血性脑损伤保护作用的机制探讨(英文)

Mechanisms of the protective effect of MK-801 against hypoxic-ischemic brain damage

目的 NMDA型谷氨酸受体的激活在缺氧缺血性脑损伤 (HIBD)的病理生理过程中具有重要的作用。该研究探讨NMDA型谷氨酸受体拮抗剂MK 80 1对HIBD的保护机制。方法 30只 7日龄SD大鼠随机分为正常对照组、HIBD组和HIBD +MK 80 1组 ,每组 1 0只 ,后两组大鼠结扎右颈总动脉后暴露于低氧环境制备HIBD模型 ,HIBD +MK 80 1组大鼠于低氧处理前腹腔注射MK 80 1 0 .3mg/kg。所有大鼠于HI后立即断头处死 ,制备脑单细胞悬液 ,以流式细胞仪测定脑细胞线粒体跨膜电势 (△Ψm)、以荧光扫描仪测定脑细胞内游离钙([Ca2 + ]i)水平。结果 与正常对照组相比 ,HIBD组大鼠双侧脑细胞△Ψm值及右 :左△Ψm比值均显著降低 ,[Ca2 + ]i显著升高 ,差异均有显著性 (P <0 .0 5或 0 .0 1 ) ;MK 80 1 +HIBD组大鼠脑细胞右 :左侧△Ψm比值较HIBD组升高 ,其差异有显著性 (P <0 .0 5 ) ,但两组间脑细胞右 :左 [Ca2 + ]i的比值无显著性差异 (P >0 .0 5 )。结论 MK 80 1对缺氧缺血性脑损伤的保护作用与其改善脑细胞线粒体功能有关 ,而与其对 [Ca2 + ]i水平的影响关系不大 ,其保护机制可能不是经过“NMDA受体 [Ca2 + ]i △Ψm”途径、而是通过“NMDA受体 其它 △Ψm”途经发挥作用。

Objective The activation of NMDA receptor plays an important role in the pathophysiological process of hypoxic ischemic brain damage (HIBD). This paper aims at studying the mechanism of the protective effect of NMDA receptor antagonist MK 801 against HIBD. Methods Thirty 7 day old SD rats were randomly assigned into Normal control, HIBD and HIBD+MK 801 groups (n=10 each). The rats in the latter two groups were kept in an environment of 8% O 2 after their right common carotid arteries were ligated. The rats in the HIBD+MK 801 group were injected with 0.3 mg/kg of MK 801 intraperitoneally before hypoxia exposure. All rats were sacrificed by decapitation immediately hypoxia and ischemia (HI). The single cell suspension of each hemisphere was prepared and the mitochondrial membrane potential (△Ψm) and intracellular free calcium ([Ca 2+ ]i) of the brain cell suspension were measured by flow cytometry and fluorescence spectrophometer respectively. Results Compared to the Normal control group, the △Ψm levels of both hemispheres and the right to left △Ψm ratio in the HIBD group decreased significantly and the [Ca 2+ ]i level increased significantly (P< 0.05 or 0.01 ); compared to the HIBD group, the △Ψm level and the right to left △Ψm ratio in the HIBD+MK 801 group increased significantly (P< 0.05 or 0.01 ). There was no difference in the right to left [Ca 2+ ]i ratio between the HIBD and the HIBD+MK 801 groups. Conclusions MK 801 may protect the neonatal brain from hypoxic ischemic damage by improving the brain cell mitochondrial function through the 'NMDA receptor other △Ψm' pathway, but not through the 'NMDA receptor [Ca 2+ ]i △Ψm' pathway.