低硒大鼠心肌线粒体型硫氧还蛋白还原酶的活性和表达

目的 探讨低硒状态下大鼠心肌线粒体型硫氧还蛋白还原酶(TR2)的活性和表达变化，分析体内硒水平改变对TR2活性的影响及其可能的机制。方法 用低硒饲料喂养断乳2周的Wistar大鼠14周，分别采用生物化学方法、Western blot和Northern blot杂交检测心肌组织中TR2的活性改变及TR2蛋白、基因表达变化。结果 低硒组大鼠心肌TR2活性降低至对照组的69．3％，差异有非常显著意义。蛋白杂交的峰面积密度扫描结果显示，常硒组为3538，低硒组为2167。Northern blot结果显示，低硒组与对照组差异无显著意义。结论 低硒能够降低心肌TR2的活性和蛋白表达水平，但并不影响此酶的基因表达。提示低硒导致心肌TR2活性降低可能是由于TR2蛋白合成过程中SeCys插入减少所致。

Effect of selenium deficiency on activity and expression of mitochondrial thioredoxin reductase of rat myocardium

Objective To study the changes of activity and expression of mitochondrial thioredoxin reductase(TR2) in activity and possible mechanism. Methods Wistar rats were fed on selenium-deficient diets for 14 weeks. The changes of TR2 activity, protein expression and gene expression were detected by biochemical methods, Western blot and Northern blot. Results Selenium dificiency caused a decrease in activity of the enzyme to 69.3% of control in cardiomyocytes, and a decrease in TR2 protein levels, but gene expression was not changed. Conclusions Selenium deficiency decreases activity and protein levels of TR2 in cardiomyocytes. These changes might be caused by the decrease of selenium(in the form of SeCys) insertion during protein synthesis.