褪黑素通过减轻内质网应激抗心肌缺血/再灌注损伤的作用及机制

Melatonin ameliorates myocardial ischemia/reperfusion injury by reducing endoplasmic reticulum stress

目的研究褪黑素（melatonin，Mel）对大鼠心肌缺血/再灌注（MI/R）损伤的预防作用与心肌内质网应激（endoplasmic reticulum stress,ER stress）水平变化情况。方法90只体质量180-220 g雄性SD大鼠，随机分为3个组：假手术（Sham）组、溶剂对照（MI/R＋V）组、Mel预防（MI/R＋Mel）组。结扎大鼠左冠状动脉前降支30min后松开结扎线恢复血流灌注，建立MI/R损伤模型，再灌注4 h后Western blot法检测ER stress水平标志分子葡萄糖调节蛋白78（glucose regulated protein78,GRP78）及CCAAT/增强子结合蛋白同源蛋白（CCAAT/enhancer-binding protein homologous protein,CHOP）和凋亡相关蛋白表达情况；再灌6 h后ELISA法检测血清酶学指标，TUNEL法检测心肌细胞凋亡率，Evans blue-TTC双染法测定梗死面积；再灌注24 h后检测各大鼠超声心动图。结果Mel预防性治疗4周可提高左室射血分数（LVEF）及左室短轴缩短率（LVFS），降低血清乳酸脱氢酶（LDH）及血清肌酸激酶（CK）水平，下调心肌细胞凋亡率及梗死面积，降低ER stress标志蛋白GGRP78及CHOP，降低凋亡通路蛋白（均P〈0.01）。结论Mel预防性治疗显著减轻心肌缺血再灌注损伤，其机制可能与抑制ER stress相关。

AIM To reperfusion （MI/R） METHODS Ninety reperfusion （MI/R, I evaluate the protective action of melatonin （Mel） against myocardial ischemia/ injury and its association with endoplasmic reticulum stress （ER stress ） level. male Sprague Dawley rats （180 -220 g） were subjected to myocardial ischemia/ 30 min, R 6 h） operation by occluding the left descending artery and were randomly divided into three groups： MI/R ＋ V （ absolute alcohol diluted in sterile saline to 0. 1 mol/L, 1 ml/d, 7 d before MI/R; 1 ml/d, 15 min before reperfusion, ip. ）, MI/R ＋Mel [10 mg/（kg ·d）, 4 weeks before MI/R] and sham （rats undergoing the same surgical procedures without tying the suture）. After the 4 - h reperfusion, ER stress marker GRP78 （ glucose regulated protein78 ）, CHOP （ CCAAT/enhancer-binding protein homologous protein） and apoptosis-related protein were measured. After the 6-h reperfusion, serum LDH and CK levels, apoptotic index and infarct size were detected. After the 24-h reperfusion, cardiac functions were evaluated. RESULTS Rats treated with Mel for 4 weeks showed markedly improved cardiac functions, lower serum LDH and CK level, decreased apoptotic index, reduced infarct size, down-regulated GRP78 and CHOP expressions and decreased apoptosis-related protein expressions （all P 〈 0. 01 ）. CONCLUSION Melatonin treatment ameliorates MI/R injury by reducing ER stress, thus improving post-MI/R cardiac functional recovery.