新生大鼠缺氧缺血性脑损伤tPA、PAI-1表达的动态变化

目的:观察新生大鼠缺氧缺血性脑损伤(HIBD)中组织型纤溶酶原激活物(tPA)和1型纤溶酶原激活物抑制剂(PAI-1)表达变化的规律,探讨纤溶系统在缺氧缺血性脑损伤中的作用。方法:7日龄SD新生大鼠96只,随机分为2组:缺氧缺血性脑损伤组和假手术组。两组动物模型制备成功后3、6、12、24、36、48、72、96小时断头取脑,应用免疫组织化学及原位杂交方法检测缺氧缺血性脑损伤不同时间点t-PA、PAI-1表达的变化。结果:假手术组新生大鼠各脑区均有tPA、PAI-1蛋白及mRNA的弱表达,缺氧缺血性脑损伤组不同时间点t-PA、PAI-1二者表达呈不同的动态变化:tPA蛋白及mRNA 3小时开始表达增强,主要见于皮质和海马,神经元表达明显,血管表达较弱,48小时神经元及微血管内皮表达明显增强,72小时神经元表达明显减弱,微血管内皮见有明显阳性表达,之后表达减弱,3～96小时各时间点阳性着色神经元数目显著高于假手术组;PAI-1蛋白及mRNA 12小时表达有所增强,神经元和微血管内皮表达增多,72小时达高峰,12～96小时各时间点阳性着色神经元数目显著高于假手术组。结论:tPA和PAI-1参与HIBD的发病机制。

Expressions of tPA and PAI-1 in neonatal rats with hypoxic-ischemic brain damage

Objective:To observe the expressions of tissue-type plasminogen activator(tPA) and plasminogen activator inhibitor-1(PAI-1) in neonatal rats with hypoxic-ischemic brain damage(HIBD) and the effect of fibrinolytic system in HIBD.Methods:Totally 96 seven-day-old SD rat pups were randomly assigned into 2 groups: sham operation group and HIBD group.Rat pups were decollated to extract brain tissue at different time points(3,6,12,24,36,48,72,96 hours) after animal models were made.The expressions of tPA and PAI-1 in rat pups were detected by immunohistochemistry and in situ hybridization methods.Results:The protein and mRNA of tPA and PAI-1 were slightly expressed in all parts of brain with sham operation group.The protein and mRNA of tPA and PAI-1 were expressed in different time points with HIBD group: tPA was expressed at 3 hours,mainly in cortex and hippocampus.It was obviously in neurons,but slightly in endothelium of capillary vessel.It was increased gradually in neurons and endothelium of capillary vessel at 48 hours.It was decreased in neurons,but still increased in endothelium of capillary vessel at 72 hours.It was decreased gradually after 72 hours.The quantities of positive neurons in HIBD group were more than sham operation group from 3 hours to 96 hours.The protein and mRNA of PAI-1 were expreesed at 12 hours.It was increased gradually in neurons and endothelium of capillary vessel,and reached to the peak at 72 hours.The quantities of positive neurons in HIBD group were more than sham operation group from 12 hours to 96 hours.Conclusion:tPA and PAI-1 participate the pathogenesis of HIBD.