促红细胞生成素保护糖尿病大鼠心功能的机制研究

Mechanisms of erythropoietin in protecting cardiac function in diabetic rats

目的 :探讨促红细胞生成素(erythropoietin,EPO)保护糖尿病大鼠心功能的相关机制。方法:雄性SD大鼠40只,随机分为正常对照组、正常+EPO干预组、糖尿病组、糖尿病+EPO干预组,每组10只。采用链脲佐菌素腹腔注射建立糖尿病动物模型,建模成功后,给予正常+EPO干预组和糖尿病+EPO干预组大鼠皮下注射EPO 1 000 IU/Kg,正常对照组和糖尿病组皮下注射等量生理盐水,每周1次,共12周。建模前及末次给药后7 d,尾静脉采血,检测血糖、血脂和血常规,超声心动图检测心功能,RT-PCR法分析内质网应激蛋白葡萄糖调节蛋白78(glucose regulated protein78,GRP78)、肌浆网Ca2+-ATP酶(SERCA2a)和EPO受体(EPOR)m RNA表达水平,Western blot技术检测GRP78、SERCA2a和EPOR蛋白表达。结果:正常对照组和正常+EPO干预组之间,心功能、血糖、血脂、血常规、GRP78、SERCA2a和EPOR蛋白表达水平均无明显差别(P>0.05)。与正常对照组和正常+EPO干预组相比,糖尿病组大鼠射血分数及左心室短轴缩短率明显下降(P﹤0.01),血糖和血脂明显升高(P﹤0.01),左心室心肌组织GRP78 m RNA及蛋白表达明显增加(P﹤0.01),SERCA2a和EPOR m RNA及蛋白表达明显减少(P﹤0.01)。与糖尿病组相比,糖尿病+EPO干预组大鼠射血分数及左心室短轴缩短率明显增加(P﹤0.01),左心室舒张末期内径明显减小(P﹤0.05),左心室收缩末期内径明显减小(P﹤0.01),左心室组织GRP78m RNA及蛋白表达明显下降(P﹤0.01),SERCA2a和EPOR m RNA及蛋白表达明显增加(P﹤0.01)。结论:EPO具有保护糖尿病大鼠心功能的作用,其机制可能是减轻心肌内质网应激,增加糖尿病大鼠心肌SERCA2a和EPOR蛋白表达。

Objective：To study the mechanisms of erythropoietin in protecting cardiac function in diabetic rats. Methods：Forty male SD rats were randomly divided into the control group,the control-EPO group,the diabetic group and the diabetic-EPO group（n=10 for each）. The diabetic model was induced by streptozotoein（STZ）. In the control-EPO and the diabetic-EPO group,rats were treated with 1 000 IU / kg EPO by subcutaneous injection once per week for twelve 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. After rats were sacrificed,myocardial tissues were collected,quantitative real-time PCR（RT-PCR） was used to detect the m RNA level of GRP78,SERCA2 a and EPOR, and Western blot was used to detect the protein expression of GRP78,SERCA2 a and EPOR. Results：Compared with the control and control-EPO group,in the diabetic group,ejection fraction（EF） and LV fractional shortening（LVFS） were decreased significantly（P﹤0.01）,blood glucose was increased significantly（P﹤0.01）,the m RNA level and the protein expression of GRP78 were increased significantly（P ﹤ 0.01）,the m RNA level and the protein expression of SERCA2 a and EPOR were decreased significantly（P﹤ 0.01）. EF and LVFS were increased significantly in EPO-treated diabetic rats（P﹤0.01）. Diabetic rats receiving EPO administration showed a significantly decrease in the m RNA level and the protein expression of GRP78 compared with the diabetic group（P ﹤ 0.01）. EPO treatment significantly increased the m RNA level and the protein expression level of SERCA2 a and EPOR（P ﹤ 0.01）. Conclusion：EPO treatment can improve the cardiac function,which might be related to the inhibition of endoplasmic reticulum stress,up-regulating of the SERCA2 a and EPOR expression.