促红细胞生成素衍生肽抑制缺血/再灌注损伤诱导的大鼠心肌细胞凋亡

Helix B surface peptide is cardioprotective through inhibition on myocardial apoptosis induced by ischemia/reperfusion injury

目的:探讨促红细胞生成素(erythropoietin,EPO)衍生肽又称螺旋B表面肽(helix B surface peptide,HBSP)在大鼠心肌缺血/再灌注损伤(I/RI)中的拮抗作用及其机制。方法:82只200～250 g雄性SD大鼠随机分为假手术(Sham)组(n=18)、缺血/再灌注(I/R)组(n=18)、EPO组(n=18)、HBSP组(n=18)及HBSP+LY294002(PI3k特异性抑制剂)组(n=10)。于灌注前5 min,于EPO组及HBSP组大鼠的尾静脉分别注射生理盐水重组人EPO(rhEPO;3 000 U/kg,4 ml/kg)及生理盐水HBSP(60μg/kg,4 ml/kg)。颈动脉插管检测血流动力学指标,采用小动物超声分别检测24 h、1周后大鼠心功能。用TTC-EB双染测定梗死面积,Western blot法检测心肌组织蛋白激酶B(Akt)和磷酸化Akt的表达。用TUNEL法检测心肌细胞凋亡。结果:与I/R组相比,EPO组和HBSP组再灌注后大鼠心脏左室收缩压(LVSP)、左室内压最大上升速率(+dp/dtmax)以及最大下降速率(-dp/dtmax)明显改善(P<0.05),左室射血分数[LVEF(%)]、室间隔厚度(IVSS)及左室短轴缩短率[FS(%)]显著增加(P<0.05),同时心肌梗死面积明显缩小(P<0.05),心肌细胞凋亡显著减少(P<0.05);HBSP组Akt磷酸化水平显著提高(P<0.05)。HBSP+LY294002组与HBSP组相比,Akt磷酸化水平明显降低,心肌细胞凋亡指数显著增高(P<0.05)。HBSP组与EPO组间各项指标均无显著差别。结论:HBSP能够显著抑制I/RI诱导的大鼠心肌细胞凋亡,减少梗死面积,明显改善心功能,其保护作用可能与激活PI3K-Akt通路有关。

AIM： To observe the protective effects and mechanism of Helix B surface peptide（HBSP） in rat myocardial ischemia/reperfusion injury.METHODS： Eighty-two Sprague Dawley rats（200-250 g） were randomly divided into five groups： sham group（n=18）,ischemia/reperfusion（I/R） group（n=18）,erythropoietin（EPO） group（3000 U/kg,4 ml/kg,n=18）,HBSP group（60 μg/kg,4 ml/kg,n=18） and HBSP＋LY294002 group（n=10）.EPO or HBSP was injected from tail veins 5 min before reperfusion.Hemodynamic values were measured via a cannula inserted into the right common carotid artery,and cardiac functions were evaluated by echocardiograph 24 h and 1 week after reperfusion.Infarct size was measured by TTC staining and the area at risk was assessed by Evans blue staining.Expressions of Akt and phospho-Akt were detected by Western blotting and apoptosis of cardiomyocytes was detected by TUNEL.RESULTS： Compared with those in I/R group,hemodynamic values of LVSP and ±dp/dtmax and cardiac functions improved after 24 h and 1 week in EPO group and HBSP group.The infarct size also reduced and cardiomyocyte apoptosis was inhibited.Cardiomyocyte apoptosis was partially inhibited after blocking the levels of PI3K-Akt in HBSP＋LY294002 group（P〈0.05）.The expressions of phospho-Akt were upregulated by HBSP and the apoptotic index of cardiomyocytes in HBSP＋LY294002 group was higher than that in HBSP group（P〈0.05）.Hemodynamic values and cardiac functions after 24 h and 1 week in the other groups were lower compared with those in sham-operated group,and the infarct size and apoptotic index of cardiomyocytes were higher than those in sham group（P〈0.05）.No statistically significant differences were found between EPO group and HBSP group.CONCLUSION： Helix B surface peptide could markedly improve heart functions and decrease the infarct size and myocardial apoptosis induced by ischemia/reperfusion injury in in vivo rats.Its protective effects may possibly be through the activation of PI3K-Akt signal pathway.