重组人促红细胞生成素对心肌梗死大鼠心肌细胞凋亡与线粒体融合基因2表达的影响

Effects of Recombinant Human Erythropoietin on Apoptosis and Mitofusin 2 Protein Expression in Rat Myocardium after Acute Myocardial Infarction

目的探讨不同剂量重组人促红细胞生成素(rHu-EPO)对心肌梗死大鼠心肌细胞凋亡和线粒体融合基因2(Mfn2蛋白)表达的影响。方法将64只成年SD大鼠随机分为模型组、大剂量治疗组(负荷量rHu-EPO5 000 U.kg-1+rHu-EPO 1500 U.kg-1术后第2,4,6天腹腔注射)、小剂量治疗组(负荷量rHu-EPO 5000 U.kg-1+rHu-EPO 750 U.kg-1术后第2,4,6天腹腔注射)和假手术组,每组16只。分别于术后24 h和2周采用脱氧核苷酸末端转移酶介导的缺口末端标记法检测心肌细胞凋亡,免疫组织化学法检测Mfn2蛋白表达。结果术后24 h假手术组、模型组、大剂量治疗组、小剂量治疗组心肌细胞凋亡指数分别为0,(60.99±5.28),(36.97±2.68),(38.10±3.41);Mfn2蛋白免疫组化染色平均吸光度分别为(0.080 6±0.013 4),(0.295 2±0.024 9),(0.125 3±0.020 9),(0.120 2±0.0197)。术后2周假手术组、模型组、大剂量治疗组、小剂量治疗组凋亡指数分别为0,(50.08±8.00),(26.54±2.97),(24.16±3.74),Mfn2蛋白免疫组化染色平均吸光度分别为(0.095 3±0.007 3),(0.247 3±0.019 1),(0.146 1±0.012 6),(0.154 2±0.010 6)。与假手术组比较,模型组凋亡指数和Mfn2蛋白表达显著增加(均P<0.05);与模型组比较,大、小剂量治疗组凋亡指数和Mfn2蛋白表达显著减少(均P<0.05);大剂量治疗组与小剂量治疗组凋亡指数和Mfn2蛋白表达差异无统计学意义。结论心肌梗死后即刻给予负荷剂量rHu-EPO并术后减量维持治疗1周可显著降低Mfn2蛋白表达,减少心肌细胞凋亡;rHu-EPO大、小剂量维持给药对Mfn2蛋白表达的调控作用和抗凋亡作用均差异无统计学意义。

Objective To investigate the effects of recombinant human erythropoietin（rHu-EPO） at different doses on myocardial apoptosis and Mfn2 protein expression in rats with myocardial infarction. Methods A total of 64 adult Sprague-Dawley rats were used and divided randomly into 4 groups： myocardial infarction（MI） rats,which were treated with 5 000 U·kg-1 loading dose followed by a maintenance dose of 1 500 U·kg-1 for 1 week of rHu-EPO（MITH）（high dose）,and low dose of MITL（a loading dose followed by a maintenance dose of 750 U·kg-1 for 1 week）,respectively,and sham eperated rats.Twenty-four hours and 2 weeks after operation,myocardial apoptosis was assessed by in situ terminal deoxynucleotidyl transferase（TdT）-dUTP nick-end labeling（TUNEL staining） and Mfn2 protein expression was measured with immunohistochemistry staining. Results Twenty-four hours after operation,apoptosis index（AI） in sham operated,MI,MITH and MITL rats was 0,（60.99±5.28）,（36.97±2.68） and（38.10±3.41）,respectively;mean optical density（MOD） of Mfn-2 protein in four groups was（0.080 6±0.0134）,（0.295 2±0.024 9）,（0.125 3±0.020 9） and（0.120 2±0.019 7）,respectively.Two weeks after operation,AI in sham operated,MI,MITH and MITL rats was 0,（50.08±8.00）,（26.54±2.97） and（24.16±3.74）;MOD of Mfn-2 protein in four groups was（0.095 3±0.007 3）,（0.247 3±0.019 1）,（0.146 1±0.012 6） and（0.154 2±0.010 6）.Twenty-four hours and 2 weeks after operation,AI and Mfn2 protein expression in MI rats were remarkably increased in comparison with sham rats（P0.05）,and those in MITH rats were significantly decreased in comparison with MI rats（P0.05）.There was no significant difference in apoptosis and Mfn2 protein expression between MITH group and MITL group（P0.05）. Conclusion Immediately loading dose followed by a maintenance（one week） lower dose of rHu-EPO can significantly reduce apoptosis and mitofusin 2 protein expression in rat myocardium after acute myocardial infarction.No significant difference in the effects by rHu-EPO on Mfn2 protein expression and apoptosis was observed between high and low dose maintenance treatments.