Effects of selenium and protein on cardiac morphology and expression of cellular glutathione peroxidase and mitochondrial thioredoxin reductase in rat myocardium / 中国地方病学杂志

ABSTRACT

Objective 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.MethodsSixty 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.