褪黑素受体对大鼠心肌缺血再灌注损伤的调控及其机制研究

The role of melatonin receptor in the protective effects of melatonin againstmyocardial ischemia reperfusion injury in rats

目的研究褪黑素膜受体(MR)在褪黑素(Mel)抗心肌缺血再灌注(MI/R)损伤机制中的作用。方法雄性SD大鼠80只随机分为四组:假手术组(Sham)、MI/R+溶剂对照组(MI/R+V)、MI/R+Mel治疗组(MI/R+Mel)、MI/R+Mel+Luz组(MI/R+Mel+Luz),Luz(Luzindole)为MR特异性阻断剂。大鼠冠状动脉左前降支结扎和松开方法建立大鼠MI/R模型,心肌缺血30 min,再灌6 h后ELISA法检测心肌组织氧化应激相关指标,TUNEL法检测心肌细胞凋亡率,Evans blue-TTC双染法测定梗死面积,Western blot法检测沉默信息转录调控因子1(SIRT1)、乙酰化叉头转录因子1(Ac-Foxo1)、Caspase-3及褪黑素受体(MR)的表达水平,再灌注72 h后超声心动图法检测各组大鼠心功能。结果与缺血再灌注组相比,Mel治疗显著改善心脏左室射血分数[LVEF,(65.18±5.863)%vs(47.37±4.201)%,P<0.01]及左室短轴缩短率[LVFS,(36.19±3.299)%vs(22.80±0.8881)%,P<0.01],下调心肌组织超氧化物[(2.881±0.1908)RLU/(mg·s)vs(3.955±0.3022)RLU/(mg·s),P<0.01]、丙二醛(MDA)生成[(269.1±11.24)pmol/mgvs(412.7±24.39)pmol/mg,P<0.01]及gp91phox的表达[(3.404±0.2440)vs(4.388±0.1463),P<0.01],上调超氧化物歧化酶(SOD)[(35.83±2.959)U/mgvs(21.11±2.004)U/mg,P<0.01]、SIRT1[(0.8033±0.05357)vs(0.3313±0.04337)],P<0.01],下调Ac-Foxo1水平[(0.2393±0.01440)vs(0.3536±0.01384),P<0.01];而Luz阻断MR后逆转Mel的上述作用(均P<0.01)。结论 Mel通过MR激活SIRT1信号通路,显著减轻大鼠MI/R氧化应激损伤,发挥抗氧化应激抗凋亡心肌保护作用。

Objective To investigate the protective effect of melatonin（Mel） on myocardial ischemia/ reperfusion（MI/ R） in-jury and the influence of melatonin membrane receptor（MR） on MI/ R injury.Methods Eighty male Sprague- Dawley rats weresubjected to myocardial ischemia / reperfusion（ MI / R, I 30 min, R 6 h） operation and randomly divided into 4 groups： Sham,MI / R＋V, MI / R＋Mel and MI / R＋Mel＋Luz（ Luzindole, the specific antagonist of MR）. The cardiac function 72 h after reperfu-sion, oxidative stress damage related indicators, apoptotic index, infarct size, MR expression, SIRT1 expression, Ac-Foxo1 expres-sion were detected.Results Compared with the MI/ R＋V group, melatonin treatment group showed improved left ventricular ejectionfraction（LVEF）（65.18±5.863）vs（47.37±4.201）,（P〈0.01） and left ventricular fractional shortening（LVFS）（36.19±3.299）vs（22.80±0.8881）,（P〈0.01）, decreased myocardium superoxide generation（2.881±0.1908） RLU/（mg·s）vs（3.955±0.3022）RLU/（mg·s）,（P〈0.01）, malondialdehyde（MDA） level（269.1±11.24） pmol/ mgvs（412.7±24.39） pmol/ mg,（P〈0.01） andgp91 phox expression（3.404± 0.2440）vs（4.388± 0.1463）,（P 0.01）, up-regulated SIRT1 expression（0.8033± 0.05357）vs（0.3313±0.04337）,（P〈0.01）, down-regulated Ac-Foxol expression（0.2393±0.01440）vs（0.3536±0.01384）,（P〈0.01）. More-over, Luz exposure significantly blocked melatonin＇s cardioprotective effect（allP〈0.01）.Conclusion The experiment showed that Mel pro-tected the heart against MI/ R injury by reducing oxidative stress damage via activation of SIRT1 signaling in a MR dependent manner.