基于微导管技术选择性动脉内低温对大鼠局灶性脑缺血基质金属蛋白酶-9表达影响

The effect of microcatheter-based selective intraarterial hypothermia on the expression of MMP-9 in rat with transient cerebral ischemia

目的探讨基于微导管技术的选择性动脉内低温对大鼠急性脑缺血-再灌注损伤后基质金属蛋白酶-9(MMP-9)表达的影响。方法应用微导管堵塞SD大鼠大脑中动脉(MCAO)2h,建立急性可逆性脑缺血动物模型。动物随机分为4组(12只/组):1非干预对照组,MCAO后,再灌注48h;2低温生理盐水全身灌注组,MCAO后即刻通过股动脉灌注0℃0.9%生理盐水2.5ml;3低温生理盐水局部灌注组,MCAO后即刻通过微导管向脑缺血区灌注0℃0.9%生理盐水2.5ml;4常温生理盐水局部灌注组,MCAO后即刻通过微导管向脑缺血区灌注37℃0.9%生理盐水2.5ml。所有动物都进行运动、神经功能评分,计算脑梗死体积、脑水肿程度,应用免疫组化定位定量脑缺血区MMP-9的表达水平。结果和非干预对照组比较,通过微导管选择性灌注0℃生理盐水能对缺血脑组织区域快速诱导低温(皮质脑温由灌注前37.2±0.2℃降低至30.5±0.4℃,纹状体温度由37.8±0.1℃降至30.8±0.4℃,P<0.01),显著改善实验动物的神经、运动功能(P<0.01),明显缩小脑梗死体积(缩小约67%,P<0.01)、减轻脑水肿程度(约70%,P<0.01),同时改组动物缺血区MMP-9阳性表达的数目显著减少(P<0.05)。而通过微导管灌注常温生理盐水及通过股动脉全身灌注低温生理盐水未显示出明显的脑保护作用,对MMP-9的表达也没有明显影响。结论通过微导管灌注低温生理盐水对急性缺血-再灌注损伤具有显著保护作用,其机制与抑制脑缺血区MMP-9表达有关。

Objective To investigate the effect of microcatheter-based selective intraarterial hypothermia on the matrix metalloproteinase-9（MMP-9） expression in rats with focal cerebral ischemia-reperfusion injury. Methods Stroke in Sprague-Dawley rats was induced by a 2-hour middle cerebral artery occlusion with a microcatheter. Rats were divided into 4 groups （n = 12 per group） ： （1） nontreatment group： 2-hour MCA occlusion followed by 48-hour of reperfusion;（2） Systemicl cold saline group： 0.9%cold saline （0℃） was applied through femoral artery in ischemie animals ; （3） Local cold saline group： 0.9% cold saline （ 0℃ ） was applied through microcatheter after 2-hour MCA occlusion ;（4） Local normothermic saline group： normothermic 0.9% saline （37℃） was applied through microcatheter. Serial functional neurologic testing after injury was performed and the expression of MMP-9 in brain tissue was observed by immunohistochemistry, followed by cerebral infarct volume evaluation 48 after reperfusion. Results Local cold saline infusion through microcatbeter achieved rapid induction of brain hypothermia before reperfusion （cerebral cortex from 37.2±0.2℃ to 30.5±0.4℃, and in the striatum from 37.8±0.1℃ to 30.8±0.4℃C ）. Compared with nontreatmeut group, Local cold saline infusion treatment reduced the cerebral infarction （67%, P〈0.01 ） and cerebral edema （70%, P〈0.01 ）, and the expression of MMP-9 in ischemic area was also markedly decreased （P〈0.05）. Systemic cold saline infusion and local normthemic saline infusion did not show neuroprotection effect.Conclusion Cold saline infused directly through microcatheter to ischemic brain area can confer great neuroprotection. The mechanism may be related to the inhibition of the expression of MMP-9.