基于SIRT1信号探讨右美托咪定对心肌缺血再灌注诱发大鼠术后认知损害的作用

Effect of Dexmedetomidine on Postoperative Cognitive Dysfunction Induced by Myocardial Ischemia-reperfusion Based on SIRT1 Signaling

目的探究右美托咪定(Dex)对心肌缺血再灌注(MIR)诱发大鼠术后认知损害(POCD)的影响及其机制。方法80只大鼠随机分为假手术组、模型组、Dex组和Dex+EX-527组(均n=20)。采用结扎左冠脉前降支、再灌注方法制备MIR模型,结扎期分别注射Dex或EX-527治疗,再灌注期收集全血用于细胞因子检测;48 h后进行避暗实验,计算各组大鼠的潜伏期和错误次数。实验结束处死大鼠取心肌和脑组织,苏木精-伊红染色观察各组大鼠心肌和脑组织的形态学改变,Masson染色计算心肌梗死面积百分率(%);ELISA方法测定血清和海马组织IL-1β、IL-6和TNF-α等炎性细胞因子,Western blot法检测海马沉默信息调节因子1/核因子E2相关因子2/血红素加氧酶1(SIRT1/NRF2/HO-1)信号通路蛋白的水平。结果与假手术组比较,模型组大鼠心肌纤维细胞损伤明显,心肌缺血染色面积(%)增加(P<0.001),外周血中心肌肌钙蛋白I(cTnI)水平升高(P<0.001),IL-1β、IL-6、TNF-α水平显著升高(均P<0.001)。避暗实验中,模型组潜伏期明显缩短(P<0.001),错误次数明显(P<0.001),且神经元形态损伤明显,IL-1β、IL-6、TNF-α水平升高(均P<0.001),SIRT1蛋白表达减少(P<0.001),HO-1和NLRP3蛋白表达增加(P<0.001);与模型组比较,Dex组大鼠心肌纤维细胞形态恢复,心肌缺血染色面积(%)减少(P<0.001);外周血中cTnI、IL-1β、IL-6和TNF-α水平降低(均P<0.001);避暗实验潜伏期延长(P<0.001),错误次数减少(P<0.001),且神经元形态恢复,IL-1β、IL-6和TNF-α水平降低(均P<0.001),SIRT1蛋白表达增加(P<0.001),HO-1和NLRP3蛋白表达均减少(均P<0.001);EX-527干预明显逆转了Dex对MIR诱发POCD的正向调节作用。结论Dex通过激活SIRT1信号,减轻神经炎症反应,改善MIR诱发的POCD症状。

Aim To investigate the effect and mechanism of dexmedetomidine(Dex)on postoperative cognitive dysfunction(POCD)induced by myocardial ischemia-reperfusion(MIR)in rats.Methods Eighty rats were randomly divided into a sham group,a model group,a Dex group and a Dex+EX-527 group.The MIR model was established by 45 min ligation of the left anterior descending coronary artery followed by 180 min reperfusion.Dex or EX-527 were treated through tail vein,and whole blood was collected for cytokine detection during reperfusion.After 48 hours,the rats in each group underwent the passive avoidance test,the latency and the number of errors in each group were calculated.At the end of the experiment,the rats were sacrificed,and the myocardial and brain tissues were collected.After HE staining the morphological changes of myocardium and brain tissue were observed,and Masson staining was used to calculate the percentage of myocardial infarction size.The levels of IL-1β,IL-6 and TNF-αin serum and hippocampus were detected by ELISA,and the protein levels of SIRT1/Nrf2/HO-1 signaling pathway in hippocampus were detected by Western blot.Results Compared with the sham group,the myocardial fiber cells in the model group were significantly damaged,and the proportion of myocardial ischemia staining area increased(P<0.001),as well as the cTnI content in peripheral blood increased(P<0.001),and the levels of inflammatory cytokines such as IL-1β,IL-6 and TNF-αsignificantly increased(P<0.001).In the passive avoidance test,the latency of rats in the model group significantly reduced(P<0.001),with a significant increase in error times(P<0.001),and the neuronal status in the brain tissue significantly damaged,and the contents of inflammatory cytokines such as IL-1β,IL-6 and TNF-αincreased(P<0.001),the expression of SIRT1 decreased(P<0.001),the expression of HO-1 and NLRP3 increased(P<0.001).Compared with the model group,the state of myocardial fibroblasts was restored and the proportion of myocardial ischemia staining area was reduced in Dex group(P<0.001),and the contents of cytokines such as cTnI,IL-1β,IL-6 and TNF-αin peripheral blood decreased(P<0.001).The latency of rats in passive avoidance test increased(P<0.001),and error times decreased(P<0.001),as well as the neuronal status was restored,and the contents of inflammatory cytokines such as IL-1β,IL-6 and TNF-αdecreased(P<0.001),the expression of SIRT1 increased(P<0.001),the expression of HO-1 and NLRP3 decreased(P<0.001).However,the treatment of EX-527 significantly reversed the positive regulatory effect of Dex on MIR-induced POCD.Conclusion Dex can alleviate the symptoms of MIR-induced POCD by activating SIRT1 signaling pathway and reducing neuroinflammatory response.