大鼠急性脑缺血模型中基质金属蛋白酶9和转化生长因子β1的表达及其组织来源分析

 目的:探讨大鼠急性缺血模型中基质金属蛋白酶9（matrix metalloproteinase 9，MMP-9）和转化生长因子β1（transforming growth factor β1，TGF-β1）的表达及其组织来源。方法:280~330 g雄性Wistar大鼠，使用线栓法建立急性大鼠脑缺血模型，并采用Zealonga 5 分制评分法评定模型建立的效果。分别取正常对照组、假处理组以及缺血后6 h、12 h、1 d、2 d、6 d和14 d组大鼠的大脑皮质和海马，采用定量 PCR检测脑组织中MMP-9和TGF-β1的表达。取对应时点各组大鼠大脑进行MMP-9和TGF-β1的原位组织化学染色。取对应时点各组大鼠血浆，以酶联免疫法（ELISA）检测MMP-9和TGF-β1的浓度变化。结果:定量PCR结果显示MMP-9 mRNA水平在急性缺血6 h即开始升高，到急性缺血2 d时最高。而TGF-β1 mRNA水平在急性缺血12 h开始升高，到急性缺血6 d时达到最高水平。与假处理组样本相比，缺血时间为12 h、1 d、2 d、6 d和14 d的样本有显著差异（P<0.05）。原位组织化学染色结果表明从急性脑缺血后1 d起，大脑的皮质和海马区域开始有MMP-9表达。急性脑缺血后2 d左右，大脑皮质的MMP-9染色最明显。在急性缺血2 d后皮质和海马区域开始能观察到TGF-β1表达，6 d时最明显。ELISA结果显示缺血后12 h，血浆中即可检测到MMP-9和TGF-β1的表达。与假处理组相比，缺血1 d时2种因子的表达差异显著（P<0.05）。结论: 大鼠急性脑缺血模型中其脑组织是急性脑缺血后MMP-9和TGF-β1的来源之一，该发现为进一步开展相关研究提供了线索。

Expression and histogenesis of matrix metalloproteinase-9 and transfor-ming growth factor-beta 1 in acute cerebral ischemia model of rats

AIM:To observe the expression and tissue localization of matrix metalloproteinase 9 (MMP-9) and transforming growth factor beta 1 (TGF-β1) in the rat acute cerebral ischemia model. METHODS:Male Wistar rats were used to establish acute cerebral ischemia model by a suturing method. The rats were divided into normal control group, sham group and ischemia 6 h, 12 h, 1 d, 2 d, 6 d and 14 d groups. The rat cerebral cortex and hippocampus of the brain were collected at different time points.The mRNA and protein levels of MMP-9 and TGF-β1 in the brain tissues were detected by real-time PCR and in situhistochemistry staining, respectively. The levels of MMP-9 and TGF-β1 in the plasma were also measured by ELISA. RESULTS:The results of real-time PCR showed that the mRNA levels of MMP-9 began to increase 6 h after acute ischemia and reached to a peak 2 d after acute ischemia. Similarly, the mRNA level of TGF-β1began to rise 12 h after acute ischemia and reached to the highest level 6 d after acute ischemia. Compared with the sham rats, the mRNA levels of MMP-9 and TGF-β1 in the rat brains that collected at ischemic time of 12 h, 1 d, 2 d, 6 d and 14 d were significantly increased. Moreover, results of in situhistochemical staining showed that the expression of MMP-9 was detected at cerebral cortex and hippocampus 1 d after acute cerebral ischemia.Further studies showed that MMP-9 dyeing of the rat cerebral cortex was most obvious 2 d after the acute cerebral ischemia. Similarly, the rat cortex and hippocampus began to express TGF-β1 2 d after acute ischemia and TGF-β1 staining at rat cerebral cortex was most obvious 6 d after the acute cerebral ischemia. In addition, ELISA showed that the increase in MMP-9 and TGF-β1 was detected in the plasma 12 h after ischemia. Compared with the sham rats, the level of these 2 factors significantly upregulated since 1 d after ischemia. CONCLUSION: The brain tissue itself contributes to the upregulation of MMP-9 and TGF-β1 post acute cerebral ischemia, which shed light on the related research in the field.