低硒大鼠心肌线粒体CytC含量的动态变化及其在心肌细胞凋亡中的作用

The dynamic change of CytC expression in cardiac mitochondria in selenium deficiency rats and its effect on myocardial apoptosis

目的检测低硒大鼠心肌线粒体中细胞色素C(CytC)的蛋白含量及心肌细胞凋亡情况,探讨低硒时CytC在线粒体介导的细胞凋亡中的作用机制。方法构建低硒大鼠模型,于喂养20、30、40周时提取心肌线粒体,Western Blot法检测线粒体中CytC的蛋白表达;免疫组织化学技术(SP法)对死亡结构域蛋白FADD进行原位染色,统计阳性细胞指数,并对CytC与心肌细胞凋亡指数进行相关性分析。结果低硒组CytC的表达与相应时段的对照组相比均降低,且随低硒喂养时间延长,降低更为明显,差异均有统计学意义(P<0.05);各时间对照组间心肌线粒体中CytC的表达无明显差异;免疫组化染色显示,随着喂养时间的延长,低硒组大鼠心肌细胞凋亡加重;相关性分析显示,线粒体内CytC表达与心肌细胞凋亡指数呈负相关(rs=-0.858,P<0.01)。结论低硒可影响大鼠心肌线粒体中CytC蛋白的表达;CytC表达与心肌细胞凋亡指数具有相关性,提示CytC在线粒体介导的心肌细胞凋亡中起重要作用。

Objective To investigate the expression of cytochrome C （CytC） protein in myocardial mitochondria in selenium deficiency rats and the apoptosis of myocardial cells so as to discuss the effect of CytC in selenium deficiency on myocardial apoptosis. Methods The model of selenium deficiency was established in twoweek-old rats. When the rats were fed for 20 week, 30 week and 40 week, the myocardial mitochondria of myocardial cells was extracted to assay the expression of mitochondrial CytC protein by Western blot and to detect the apoptosis of myocardial cells by immunohistochemistry （SP method）. We then tested the index of myocardial cells and analyzed the correlation between CytC and apoptosis index of myocardial cells. Results The expression of CytC protein in low-selenium （LS） groups was decreased significantly compared with that in normal control （NC） groups of corresponding time point （P〈0.05）; as low-selenium feeding time prolonged, it was reduced significantly in LS subgroups （P〈0.05）. However, there was no significant difference between NC subgroups （P〈0.05）. With the prolonging of low-selenium feeding time, the number of apoptotic myocardial cells in LS group was increased. The correlation analysis indicated that mitochondrial CytC was negatively correlated with the apoptosis index of myocardial cells （r =- 0. 858, P 〈 0. 01）. Conclusion Selenium deficiency can affect the expression of mitochondrial CytC protein in rats. CytC is correlated with the apoptosis index of myocardial cells, suggesting that it plays an important role in the mitochondria-mediated apoptosis of myocardial cells.