四周尾部悬吊大鼠颈总动脉MMP9和TIMP1的表达及活性改变

Changes of MMP9 and TIMP1 Expressions and Activity in the Carotid Artery of 4 wk Hindlimb Unweighted Rat

目的:探讨四周尾部悬吊模拟失重大鼠颈总动脉基质金属蛋白酶(matrix metalloprotein9,MMP9)和金属蛋白酶组织抑制剂1(tissue inhibitor of metalloproteinase1,TIMP1)的基因、蛋白表达及酶活性变化。方法:采用4周(week,wk)尾部悬吊大鼠模拟失重影响,通过透射电镜检测颈总动脉壁基质含量,实时定量聚合酶链式反应检测MMP9和TIMP1的mRNA表达,Western blot和免疫组织化学染色检测其蛋白表达和分布,明胶酶谱法测定MMP9活性水平。结果:与对照组相比,悬吊组大鼠细胞外基质面积较对照组显著增加(P<0.05),胶原蛋白含量显著增加(P<0.05);悬吊组大鼠颈总动脉MMP9的m RNA表达量无明显改变,而其蛋白表达量和酶活性均显著降低(P<0.05);TIMP1 mRNA和蛋白表达量则显著升高(P<0.05)。结论:模拟失重使大鼠颈总动脉MMP9水平降低,TIMP1水平升高,可能与其管壁基质增生和胶原蛋白含量增加有关。

Objective：To investigate the changes of gene or protein expression and activity of matrix metalloprotein9 （MMP9） and tissue inhibitor ofmetalloproteinasel （TIMP1） in the carotid artery （CA） of 4 wk hindlimb unweighted rat.Methods：A 4 weeks（wk） hindlimb unweighted （HU） rat model was used to simulate the effect of weightlessness on the cardiovascular system.Transmission electron microscopy was used to detect the content of ECM.Reverse transcriptase polymerase chain reaction（RT-PCR） was conducted to measure the mRNA content MMP and TIMP1.Immunohistochemistry and Western blot technique were used to measure the protein abundance.Gelatin zymography was carried out to detect the activity of MMP9.Results：Compared to the control group （CON）,the area of ECM was enhanced （P＜0.05） and the content of collage fiber was increased （P＜0.05） in the CA of HU rats;moreover,HU did not affect the mRNA expression of MMP9,but significantly reduced the protein content （P＜0.05） or enzymatic activity （P＜0.05）.Accordingly,the mRNA or protein expression of TIMP1 in the CA was significantly increased by HU （P＜0.05）.Conclusion：Simulated weightlessness caused imbalance between MMP and TIMP1 expression,which might contribute to the ECM aggregation and stiffness of CA.