硒对人心肌谷胱甘肽过氧化物酶基因表达影响的研究

Effect of selenium on human myocardial glutathione peroxidase gene expression

目的：从基因表达水平研究临床心肌缺血／再灌注期间微量元素硒（Ｓｅ）对人心肌谷胱甘肽过氧化物酶（ＧＰＸ）基因表达的影响，探讨硒拮抗自由基损伤的机制。方法：将心脏手术病人分为对照组和服硒组。利用生化、ＲＴ－ＰＣＲ、基因测序等方法，分别对两组病人心肌缺血前和再灌注后３０分钟的心肌ＧＰＸ活性及心肌、血浆和血细胞Ｓｅ浓度、ＧＰＸｍＲＮＡ水平及其ｃＤＮＡ序列进行测定和组间比较。结果：口服７天Ｓｅ未引起服硒组病人血浆和血细胞Ｓｅ含量明显改变，但服硒组在心肌再灌注后的心肌ＧＰＸ活性增加幅度、Ｓｅ含量，以及缺血前和再灌注后ＧＰＸ表达阳性率（７３．９％对８２．６％）都高于对照组（３９．１％对６０．９％），同时ｃＤＮＡ序列正常。结论：补充微量元素硒可提高再灌注３０分钟时心肌的Ｓｅ含量和ＧＰＸ表达水平，并有效拮抗此过程产生的自由基对心肌细胞的脂质过氧化损伤。

Aim:This research elucidates clinically the effect of selenium (Se) to human myocardial flutathione peroxidase gene expression,and Se inhibiting effect to free radical damage.Methods:46 patients with ASD or VSD were divided into two groups,the control group(n=23) and the Se supplementation group(n=23).The Se supplementation group received Se 400μg/day for 7 days before operation.Biochemical techniques,atomic absorption,RT PCR and cDNA sequence testing methods were used to evaluate and compare the changes during ischemia/reperfusion period(I/P) in myocardial MDA level,GPX activity and gene expression level,GPX cDNA nucleotide sequence,Se and Ca and Mg concentration.Results:(1)Before ischemia,selenium concentration in either plasma or blood cell did not show significantly change in both control and Se groups.The mean level of GPX activity in Se group was slightly lower than control group,the MDA level was equal,and (2)After 30min of reperfussion,Se level in plasma and blood cell kept consistent,while myocardial Se concentration and GPX gene expression rating in Se group increased significantly,and the MDA level reduced 4.2% compared to a 8.2% rise in control group,but the mean level of GPX activity in Se group was slightly lower than that in control group.Either pre or post myocardial reperfusion,Se group had a higher rate of myocardial GPX gene expression,and the nucleotide sequence was normal.Conclusion:Se supplementation could increase myocardial Se content and improve GPX gene expression during I/R,and in this way to against free radical peroxidizing damage on myocardium.