沉默信息调节因子1在缺血预处理减轻大鼠心肌缺血再灌注损伤中的作用

Role of silent information regulator 1 in ischemic preconditioning-induced alleviation of myocardial ischemia-reperfusion injury

目的 探讨沉默信息调节因子1（SIRT1）在缺血预处理减轻大鼠心肌缺血再灌注损伤中的作用.方法 雄性SD大鼠48只,体重200 ～ 250 g,12周龄,采用随机数字表法,将其分为4组（n=12）：假手术组（S组）、缺血再灌注组（I/R组）、缺血预处理组（IPC组）和缺血预处理＋SIRT1抑制剂组（IPC＋ ex527组）.采用结扎左冠状动脉前降支30 min再灌注120 min的方法制备心肌缺血再灌注损伤模型,IPC组和IPC＋ ex527组进行缺血预处理（缺血5 min,再灌注5 min,重复3个循环,共30 min）,IPC＋ ex527组分别于缺血前15 min及再灌注前1 min静脉注射ex527 1 μg/kg.分别于缺血前和再灌注120 min时采集股动脉血样,测定血清TNF-α和IL-6的浓度,处死大鼠,取心肌组织,测定乳酸脱氢酶（LDH）、肌酸激酶同工酶（CK-MB）活性、SIRT1表达和NF-κB p65乙酰化水平.结果 与S组比较,I/R组和IPC＋ ex527组再灌注120 min时血清TNF-α、IL-6浓度、心肌组织LDH、CK-MB活性和NF-κB p65乙酰化水平升高,心肌组织SIRT1表达下调（P＜0.05）；与I/R组比较,IPC组血清TNF-α、IL-6浓度、心肌组织LDH、CK-MB活性、NF-κB p65乙酰化水平降低,心肌组织SIRT1表达上调（P＜0.05）,IPC＋ ex527组上述指标差异无统计学意义（P＞0.05）；与IPC组比较,IPC＋ ex527组血清TNF-α、IL-6浓度、心肌组织LDH、CK-MB活性、NF-κB p65乙酰化水平升高,心肌组织SIRT1表达下调（P＜0.05）.结论 SIRT1参与了缺血预处理减轻大鼠心肌缺血再灌注损伤.

Objective To evaluate the role of silent information regulator 1 （SIRT1） in ischemic preconditioning （IPC）-induced alleviation of myocardial ischemia-reperfusion （I/R） injury in rats.Methods Forty-eight male Sprague-Dawley rats,aged 12 weeks,weighing 200-250 g,were randomly divided into 4 groups （n =12 each）：sham operation group （S group）,I/R group,IPC group and IPC ＋ SIRT1 inhibitor ex527 group （IPC ＋ ex527 group）.Myocardial I/R was induced by 30 min occlusion of left anterior descending branch of coronary artery followed by 120 min reperfusion.IPC was induced by 3 episodes of 5 min occlusion of left anterior descending branch at 5 min intervals before myocardial ischemia.SIRT1 inhibitor ex527 1 μg/kg was injected intravenously 15 min before myocardial ischemia and at 1 min before reperfusion.Blood samples were collected before myocardial ischemia and at 120 min of reperfusion for measurement of serum TNF-α and IL-6 concentrations by ELISA.The rats were then sacrificed and myocardial specimens were obtained for determination of myocardial lactic dehydrogenase （LDH） and creatine kinase MB （CK-MB） activities,SIRT1 expression and acetylation of NF-κB p65.Results Compared with S group,the serum TNF-α and IL-6 concentrations at 120 min of reperfusion,and myocardial LDH and CK-MB activities and acetylation of NF-κB p65 were significantly increased,and SIRT1 expression was down-regulated in I/R and IPC ＋ ex527 groups （P ＜ 0.05）.Compared with I/R group,the serum TNF-α and IL6 concentrations at 120 min of reperfusion,and myocardial LDH and CK-MB activities and acetylation of NF-κB p65 were significantly decreased,SIRT1 expression was up-upregulated in group IPC （P ＜ 0.05）,and no significant change was found in the parameters mentioned above in group IPC ＋ ex527 （P ＞ 0.05）.Compared with IPC group,the serum TNF-α and IL-6 concentrations at 120 min of reperfusion,and myocardial LDH and CK-MB activities and acetylation of NF-κB p65 were significantly increased,and SIRT1 expression was down-regulated in group IPC ＋ ex527 （P ＜ 0.05）.Conclusion SIRT1 is involved in IPC-induced alleviation of myocardial I/R injury in rats.