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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 role of melatonin membrane receptor (MR) in the mechanism of melatonin (Mel) against myocardial ischemia / reperfusion (MI / R) injury. Methods Eighty male Sprague-Dawley rats were randomly divided into four groups: sham group, MI / R + solvent group (MI / R + V), MI / R + Mel group / R + Mel + Luz group (MI / R + Mel + Luz), Luz (Luzindole) MR-specific blockers. Rat MI / R model was established by ligation and loosening of the left anterior descending coronary artery in rats. Myocardial ischemia 30 min, reperfusion 6 h after myocardial oxidative stress-related indicators measured by ELISA, TUNEL assay myocardial cell apoptosis The area of infarction was determined by Evans blue-TTC double staining method. The expressions of SIRT1, Ac-Foxo1, Caspase-3 and melatonin receptor (MR) ), And 72 h after reperfusion, cardiac function of rats in each group was detected by echocardiography. Results Mel treatment significantly improved left ventricular ejection fraction [LVEF (65.18 ± 5.863)% vs (47.37 ± 4.201)%, P <0.01] and left ventricular fractional shortening [LVFS (2.881 ± 0.1908) RLU / (mg · s) vs (3.955 ± 0.3022) RLU / (mg · s) vs (22.80 ± 0.8881)%, P <0.01] (P <0.01), and the expression of gp91phox [(3.404 ± 0.2440) vs (4.388 ± 0.2440, P <0.01, P <0.01] (P <0.01), SIRT1 [(0.8033 ± 0.05357) vs (P <0.01), P <0.01] 0.3313 ± 0.04337)], P <0.01], down-regulated the level of Ac-Foxo1 (0.2393 ± 0.01440 vs 0.3536 ± 0.01384, P <0.01) ). Conclusion Mel activates the SIRT1 signaling pathway by MR and significantly attenuates the oxidative stress injury induced by MI / R in rats and exerts anti-apoptotic myocardial protective effect against oxidative stress.