缺血预处理对脑缺血血脑屏障通透性和MMP-9表达的影响

Ischemic Preconditioning Influences Blood-Brain Barrier Permeability and MMP-9 Expression of Ischemic Brain

目的 研究缺血预处理 (IP)对再缺血脑组织血脑屏障通透性和MMP 9表达的影响。方法 3组SD大鼠分别给予 :①一侧颈内动脉注射生理盐水 (SI) ;②双侧颈总动脉夹闭 (BCAO) ;③双侧颈总动脉夹闭同时一侧颈内动脉注射生理盐水 (BS)处理。 2 4h后 ,应用动脉腔内线栓法作大脑中动脉阻断 (MCAO) ,观察 3种预处理对再缺血脑组织含水量、血脑屏障 (BBB)通透性和MMP 9表达的影响。结果 缺血 2 4和 48hBS组脑含水量均值分别为 82 .92 %和 83.12 % ,SI组和BCAO组分别为 85 .2 9%、85 .96 %和 86 .17%、85 .5 8% ;缺血 2 4和 48hBS组脑EB含量均值分别为 14.0 1和 11.74μg/mm3 ,明显低于SI和BCAO组 (P <0 .0 1) ;BS组MMP 9mR NA和蛋白水平的表达水平明显低于其他两组 (P <0 .0 1)。结论 诱导脑缺血耐受的BS预处理能明显减轻再缺血性脑水肿和BBB损伤 ,降低MMP

Purpose: To investigate the influence of ischemic preconditioning (IP) on permeability of blood-brain barrier (BBB) and expression of matrix metalloproteinase-9 (MMP-9) in subsequent ischemic hemisphere. Methods: Three groups of SD rats were given three different pretreatments. The first group of rats (SI) were only injected with saline into right internal carotid artery, the second group of rats (BCAO) were given both carotid artery occlusion and the third group (BS) were given BCAO with SI simultaneously. 24 h after pretreatments, focal cerebral ischemia were made using the method of thread inserting right middle cerebral artery occlusion (MCAO). Brain water content, BBB permeability and MMP-9 expressin of ischemic hemisphere brains were measured 24 and 48 h after MCAO. Results: In BS group, brain water content (mean) were 82. 92% and 83.12%, whereas in SI and BCAO group were 85.29%, 85. 96% and 86.17%, 85.58% 24 and 48 h after MCAO. EB content of ischemic hemispheres were 14.01 and 11.74 μg/mm3 24 h and 48 h after MCAO, lower than in other two groups (P< 0.01). MMP-9 expression of ischemic hemisphere in protein and mRNA levels in BS group was lower than in other two groups (P<0.01). Conclusions: Ischemic preconditioning could ameliorate brain edema and BBB disruption caused by subsequent cerebral ischemia, and decrease MMP-9 expression. This may be an important mechanism of cerebral ishemic tolerance.