高血压与外源性MMPs对大鼠脑动脉瘤形成的影响研究

Study on the effect of exogenous MMPs and hypertension on the cerebral aneurysm formation in rats

目的探讨高血压与外源性金属基质蛋白酶(MMPs)在大鼠脑动脉瘤形成过程中的影响。方法健康成年雄性SD大鼠32只,随机分为高血压组和MMPs组,每组16只,前者手术造成大鼠肾性高血压,后者应用外源性MMP-2、MMP-9干预,分别于术后1、3和5周采集标本,观察脑动脉瘤形成情况,并应用ELISA、免疫组化法和RT-PCR检测MMPs及其表达水平。结果高血压组在术后3周血压达稳定峰值,病理学观察见5只大鼠的脑底动脉环分叉部有明显动脉瘤形成,MMPs组脑底动脉环结构基本正常。高血压组血浆MMP-2、MMP-9浓度在术后逐渐增高,且在术后3、5周,与MMPs组比较差异均有统计学意义(P<0.05)。免疫组化见高血压组在术后3周脑动脉壁胞浆中MMP-2和MMP-9表达明显增加,持续至第5周,而MMPs组仅有弱阳性表达。RT-PCR检测显示高血压组在术后3周脑动脉壁MMP-2和MMP-9基因表达增加,持续至第5周,而MMPs组仅有较弱的基因表达。结论血压持续升高可能是MMPs被异常激活的一个重要启动因素,机制较为复杂;单纯外源性MMPs在脑动脉瘤形成中可能难以有效发挥作用。

Objective To explore the effect of hypertension and exogenous matrix metalloproteinases（MMPs） on the cerebral aneurysm formation in rats. Methods 32 healthy male adult SD rats were randomly divided into hypertension group and MMPs group（16 cases per group）. The rats of hypertension group were induced to have renal hypertension by operation,while the rats of MMPs group were administrated with exogenous MMP-2 and MMP-9. Specimens were collected 1 w, 3 w and 5 w after operation. Formative cerebral aneurysms were observed. The dynamic changes of MMP-2 and MMP-9expression were examined by ELISA, RT-PCR, and immunohistoehemistry. Results Arterial pressures of the rats reached stable peak 3w after operation in hypertension group. Aneurysms were obvious in the bifurcations of Wills arterial ring in 5rats; the structure of Wills arterial ring was basically normal in MMPs group. In hypertension group plasma concentrations of MMP-2 and MMP-9 were gradually increased after operation, compared with MMPs group. The concentration difference of MMP-2 and MMP-9 had statistical significance in 3 w and 5 w after operation（P 0.05）. Immunohistochemistry results showed that the expression levels of MMP-2 and MMP-9 in the cytoplasm of cerebral artery wall were significantly increased in 3 w after operation in hypertension group, and continue increase to 5 w, but there were only weakly positive expression in MMPs group. The gene expression levels of MMP-2 and MMP-9 in cerebral artery detected by RT-PCR were increased in 3 w after operation in hypertension group, and continue increase to 5 w, but the gene expression levels were weak in MMPs group. Conclusion Sustaining hypertension was an important initiating factor of plentiful activation of MMPs,and the mechanism was comparatively complex. Exogenous MMPs alone might not be effective to inhibit the formation of cerebral aneurysms.