κ-阿片受体介导的抗心肌缺血再灌注损伤的线粒体机制

The relationship between the anti-myocardial ischemia-reperfusion (I/R) injury mediated by κ-opioid receptor (κ-OR) and mitochondria remains unclear. Our previous study suggested that κ-OR activation protected against ischemic heart injury via PI3K/Akt signaling pathway and it improved mitochondrial morphological changes induced by I/R. However, whether κ-OR activation protects against ischemic heart injury via mitochondrial kinetics and function remains undetermined. Our recent study indicated that I/R down-regulated Mfn2 expression of mitochondrial fusion protein and up-regulated Drp1 expression of mitochondrial fission protein, which was reversed by κ-OR activation, suggesting that κ-OR activation inhibits mitochondrial fusion-fission imbalance triggered by I/R and involved in the regulation of mitochondrial function. However, whether κ-OR ameliorates this imbalance and regulates mitochondrial function via PI3K/Akt signaling remain unclarified. The current project uses knock-out mice along with myocardium-specific over-expression or RNAi, and aims to investigate whether κ-OR activation inhibits mitochondrial fusion-fission imbalance, improves mitochondrial dysfunction, and protects against ischemic heart injury via PI3K/Akt/FoxO3a signaling in vivo and in vitro. Our study will provide new insights into the mitochondrial mechanism underlying the effect of anti-myocardial I/R injury mediated by κ-OR and lay the experimental foundation for the clinical application of opioid drugs in the prevention and management of ischemic heart disease.

κ-阿片受体（κ-OR）介导的抗缺血再灌注（I/R）损伤的心肌保护作用与线粒体的关系尚不清楚。我们前期研究发现，激动κ-OR可通过激活PI3K/Akt信号保护缺血心肌，同时意外发现其可显著改善I/R引起的线粒体形态改变，近期预实验发现，I/R可下调心肌线粒体融合蛋白Mfn2的表达，上调分裂蛋白Drp1的表达，而激活κ-OR可逆转以上结果，提示激活κ-OR可抑制I/R诱导的心肌线粒体融合-分裂失衡并可能参与了对I/R心肌线粒体功能的调节。然而κ-OR对I/R心肌线粒体功能的调节作用及机制尚不清楚。本项目拟采用基因敲除小鼠，结合过表达或RNAi等技术，探讨激活κ-OR是否可通过PI3K/Akt/FoxO3a途径，抑制线粒体融合-分裂失衡，改善线粒体功能，从而保护缺血心肌，以期为认识κ-OR介导的抗心肌I/R损伤的线粒体机制提供新的学术资料，并为临床应用阿片类药物防治缺血性心脏病奠定实验基础。

线粒体动力学变化导致线粒体功能障是介导心肌缺血/再灌注（I/R）损伤的关键病理过程。本课题前期研究结果表明激活κ-阿片受体（κ-OR）可显著抑制心肌I/R损伤，然而κ-OR介导的抗I/R损伤的心肌保护作用与线粒体的关系尚不清楚。本研究分别从动物水平和细胞水平，利用生理学、分子生物学、免疫组织化学等多种方法深入系统地研究了κ-OR激动剂U50,488H发挥抗I/R损伤的线粒体机制。课题研究发现：1）I/R损伤过程中心肌组织中线粒体动力学严重失衡、线粒体功能紊乱，而激活κ-OR可显著减轻I/R心肌损伤，改善心脏功能，发挥抗I/R心肌损伤作用，其保护作用与激活AMPK信号通路抑制I/R引起的线粒体功能障碍有关；2）通过对线粒体动力学变化进行探究，发现κ-OR活化可分别通过激活Stat3磷酸化和PI3K/Akt信号通路调控线粒体融合蛋白Opa1的表达和分裂蛋白Drp1磷酸化，进而促进线粒体融合，抑制线粒体分裂，减轻I/R引起的线粒体动力学失衡；3）通过对心肌线粒体外膜Drp1结合蛋白变化进行观察，发现激活κ-OR可通过抑制I/R心肌Drp1结合蛋白Mid51的上调调控Drp1的线粒体转位，进而抑制线粒体异常分裂，改善线粒体功能，发挥抗I/R损伤作用。综上所述，本课题研究首次揭示了激动κ-OR可通过多种途径维持线粒体动力学平衡，改善线粒体功能，从而发挥抗MI/R损伤作用，研究结果为临床应用κ-阿片受体激动剂防治缺血性心脏病提供新思路和实验基础。