摘要目的 观察硒和蛋白质对大鼠心肌形态结构及谷胱甘肽过氧化物酶(GPX1)、线粒体型硫氧还蛋白还原酶(TR2)表达的影响.方法 选取健康纯系断乳雄性Wistar大鼠60只,按2×2析因设计分为4组,每组15只.饮水分为低硒(0 mg/L)、常硒(0.25 mg/L)2个水平；饲料分别为低蛋白(10％蛋白+0.008 mg/kg硒)、常蛋白(20％蛋白+ 0.015～0.026 mg/kg硒)2个水平.饲养1年后处死,光镜下观察心肌组织病理改变,免疫组化法和Westem blot法检测GPX1和TR2在大鼠心肌组织的表达水平.结果 各组大鼠心肌坏死率比较,差异有统计学意义(x2=11.04,P＜ 0.05),其中低硒低蛋白组[66.7％(8/12)]明显高于常硒常蛋白组[7.1％(1/14),x2=11.06,P＜ 0.05].免疫组化法检测,低硒低蛋白组、常硒低蛋白组、低硒常蛋白组、常硒常蛋白组大鼠心肌组织GPX1表达阳性率分别为0(0/12)、81.8％(9/11)、10.0％(1/10)、100.0％(14/14),其中常硒低蛋白组和常硒常蛋白组阳性率明显高于低硒低蛋白组和低硒常蛋白组(x2值分别为12.88、8.14和35.89、32.60,P均＜ 0.05)；TR2阳性率分别为0(0/12)、81.8％(9/11)、0(0/10)、100.0％(14/14),其中常硒低蛋白组和常硒常蛋白组阳性率明显高于低硒低蛋白组和低硒常蛋白组(x2值分别为28.67、18.25和35.89、32.60,P均＜0.05).Western blot法检测,上述4组大鼠心肌组织GPX1蛋白表达分别为0.87±0.13、1.18±0.13、0.95±0.13、1.74±0.23,经析因分析,硒和蛋白质水平对心肌细胞GPX1表达具有影响作用(F值分别为124.93、43.16,P均＜0.05),且硒和蛋白质间有交互作用(F=24.10,P＜0.05)；TR2蛋白表达分别为0.63±0.19、0.97±0.24、0.55±0.08、1.03±0.31,经析因分析,硒因素对心肌细胞TR2表达具有影响作用(F=36.97,P＜0.05).结论 常硒和常蛋白相对于低硒和低蛋白都可以提高心脏GPX1和TR2表达水平,增强心肌组织抗氧化能力,保护心肌内皮细胞,降低心肌的损伤程度,且二者联合作用较好.

abstractsObjective To study the effects of selenium(Se) and protein on cardiac morphology and expression of cellular glutathione peroxidase(GPX1 ) and mitochondrial thioredoxin reductase(TR2) in rat myocardial tissue.Methods Sixty healthy weaning male Wistar rats were randomly divided into four groups by two factors two levels factorial design(n =15).Drinking water was divided into two levels of Se-deficient(0 mg/L) and Se-adequate (0.25 mg/L); diet was divided into two levels of protein-deficeient (10％ protein and 0.008 mg/kg Se) and protein-adequate(20％ protein and 0.015 - 0.026 mg/kg Se).The rats were killed after feeding for one year.Pathological changes in myocardial tissues were observed under light microscope.The expression of GPX1 and TR2 in rat myocardial tissue was detected by immunohistochemistry and Western blotting.Results Compared between groups,the difference of the rate of myocardial necrosis in rats was statistically significant(x2 =11.04,P ＜ 0.05),in which Se-deficient protein-deficient group [66.7％ (8/12) ] was significantly higher than Se-adequate proteinadequate group [ 7.1％ ( 1 / 14),x2 - 11.06,P ＜ 0.05 ].GPX 1 positive rates in Se-deficient protein-deficient group,Se-adequate protein-deficient group,Se-deficient protein-adequate group and Se-adequate protein-adequate group were 0(0/12),81.8％(9/11 ),10.0％(1/10) and 100.0％(14/14),respectively,in rat myocardial tissue determined by immunohistochemistry.Of which,Se-adequate protein-deficient group and Se-adequate protein-adequate group were significantly higher than Se-deficient protein-deficient group and Se-deficient protein-adequate group(x2 =12.88,8.14 and 35.89,32.60,all P ＜ 0.05).The positive expression rates of TR2 in rats myocardial tissue of the four groups were 0(0/12),81.8％(9/11),0(0/10) and 100.0％(14/14),respectively.Of which,Se-adequate proteindeficient group and Se-adequate protein-adequate group were significantly higher than Se-deficient protein-deficient group and Se-deficient protein-adequate group (x2 =28.67,18.25 and 35.89,32.60,all P ＜ 0.05).The four groups'results of the overall mean of the relatively value of protein expression of GPX1 in cardiac tissue by Western blotting were 0.87 ± 0.13,1.18 ± 0.13,0.95 ± 0.13 and 1.74 ± 0.23,respectively.Through analysis of variance of factorial design,the effects of Se and protein on protein expression of GPX1 in the heart were statistically significant(F=124.93,43.16,all P＜ 0.05).And there was interaction between them(F=24.10,P＜ 0.05).The four groups'results of the overall mean of the relatively value of protein expression of TR2 in cardiac tissue by Western blotting were 0.63 ± 0.19,0.97 ± 0.24,0.55 ± 0.08 and 1.03 ± 0.31,respectively.Through analysis of variance of factorial design,the effect of Se on expression of TR2 in the heart was statistically significant(F =36.97,P ＜ 0.05).Conclusions Adequate Se and protein diet can increase the levels of GPX1 and TR2 in the heart compared to deficient Se and protein diet,can enhance anti-oxidizing ability,protect the myocardial endothelial cells,reduce degree of myocardial injury,and the combined effects of both are better.