促红细胞生成素对糖尿病大鼠心肌血管内皮生长因子表达及心功能的影响

Effects of erythropoietin on myocardial vascular endothelial growth factor expression and cardiac dysfunction in diabetic rats

目的探讨促红细胞生成素(EPO)对糖尿病大鼠心肌组织血管内皮生长因子(VEGF)和EPO受体(EPOR)表达,以及心脏结构和功能的影响。方法雄性SD大鼠36只,随机分为正常对照组、糖尿病组和EPO组,均n=12。采用链脲佐菌素单次腹腔注射建立糖尿病动物模型,制模成功后,EPO组大鼠皮下注射EPO 1 000 IU·kg^(-1),每周1次,共12 wk。末次给药后d 7,尾静脉采血,检测血常规和血糖,流式细胞术测定外周血中内皮祖细胞(EPCs)数量,RT-PCR法分析VEGF和EPOR mRNA表达水平,Western blot技术检测VEGF和EPOR蛋白表达,免疫组化法检测左室心肌毛细血管密度,超声心动图检测心功能。结果与正常对照组比较,糖尿病大鼠EPCs数量、左心室心肌组织VEGF和EPOR蛋白和mRNA表达及毛细血管密度均显著减少(P<0.01),左室舒张末期内径(LVDd)和左室收缩末期内径(LVDs)明显增加(P<0.05),射血分数(EF)显著下降(P<0.01)。与糖尿病组相比,EPO组大鼠EPCs数量、左心室心肌组织VEGF和EPOR蛋白和mRNA表达及毛细血管密度均显著增加(P<0.01),EF值明显增加(P<0.05),LVDd和LVDs明显减少(P<0.05)。结论 EPO可增加糖尿病大鼠EPOR和VEGF蛋白和mRNA表达,增加EPCs数量和心肌新生血管的生成,改善心功能。

AIM To investigate the effects of erythropoietin （EPO） on ventricular remodeling, cardiac function and the expressions of vascular endothelial growth factor （VEGF） and EPO- receptor （EPOR） in diabetic rats. METHODS Thirty-six male SD rats were randomly divided into control group, diabetic group and EPO-treated group （n = 12 for each）. The diabetic model was induced by streptozotocin （STZ）. In the EPO- treated group, diabetic rats were treated with 1 000 IU.kg-1 EPO by subcutaneous injection once per week fortwelve weeks. At the seventh day after the last administration, echocardiography was conducted. Blood samples from tail vein were collected for blood glucose and red blood cell numbers measurements. Counting of peripheral blood endothelial progenitor cells （EPCs） was analyzed by flow cytometry. Collecting myocardial tissues, quantitative real-time PCR （RT-PCR） was used to detect the mRNA level of VEGF and EPOR, and Western blot was used to detect the protein expression of VEGF and EPOR. CD31 level in the myocardium was determined by immunohistochemistry in terms of capillary density. RESULTS Compared with the control group, EPCs numbers and the capillary density of rats reduced significantly in the diabetic group. The mRNA levels and the protein expressions of VEGF and EPOR also decreased （P 〈 0.01） . And LVDd and LVDs increased, ejection fraction （EF） decreased significantly in STZ induced diabetic rats. Rats receiving the EPO injection showed a significant increase in circulating EPCs compared with the diabetic group rats （P 〈 0.01） . EPO treatment significantly increased the mRNA levels and the protein expressions of VEGF and EPOR, and the capillary density compared with diabetic rats （P 〈 0.01） . LVDd and LVDs significantly decreased and EF increased in the EPO- treated group compared with the diabetic group （P 〈 0.05）. CONCLUSION EPO treatment can increase EPCs, the protein and mRNA revascularization. These might be one of the mechanisms expression levels of VEGF and EPOR, and improve of EPO protecting cardiac function in diabetic rats.