Chen Wei Ren, Liu Hong Bin, Chen Yun Dai, Sha Yuan, Ma Qiang, Zhu Ping Jun, Mu Yang
Department of Cardiology, Nanlou Division, Chinese PLA General Hospital, National Clinical Research Center for Geriatric Diseases, Beijing, China.
Department of Cardiology, Chinese PLA General Hospital, Beijing, China.
Cell Physiol Biochem. 2018;47(5):2067-2076. doi: 10.1159/000491474. Epub 2018 Jul 5.
BACKGROUND/AIMS: Melatonin has been demonstrated to protect cardiac microvascular endothelial cells (CMECs) against ischemia/reperfusion injury (IRI). Autophagy plays different roles in the heart during ischemia and reperfusion. The AMP activated protein kinase/mammalian target of rapamycin (AMPK/mTOR) pathway is associated with autophagy. This study sought to explore whether melatonin regulates CMEC autophagy through the AMPK/mTOR signaling pathway.
The effects of melatonin in IRI were investigated in vivo rat models and in vitro neonatal CMECs. Myocardial infarct size was achieved by Evans blue and triphenyltetrazolium chloride staining. The severity of cell injury was evaluated by cell vitality and lactate dehydrogenase (LDH) release assays, and autophagy was evaluated by transmission electron microscopy and the assessment of autophagy-related gene expression, such as that of Beclin 1 and light chain 3-II.
In vivo, melatonin markedly reduced infarcted area, improved cardiac function and decreased LDH release. However, the AMPK activator AICAR and the mTOR inhibitor rapamycin reduced the protective effects of melatonin on IRI. In vitro, Beclin1 and light chain 3-II protein were found to be down-regulated and autophagosomes were found to be reduced in response to melatonin, together with an increase in cell vitality and a decrease in LDH. Treatment with AICAR or rapamycin ablated the benefit observed with melatonin treatment.
Melatonin played an important and protective role in CMECs by inhibiting autophagy against IRI via the AMPK/mTOR system.
背景/目的：褪黑素已被证明可保护心脏微血管内皮细胞（CMECs）免受缺血/再灌注损伤（IRI）。自噬在心脏缺血和再灌注过程中发挥着不同作用。AMP激活的蛋白激酶/雷帕霉素哺乳动物靶蛋白（AMPK/mTOR）通路与自噬相关。本研究旨在探讨褪黑素是否通过AMPK/mTOR信号通路调节CMEC自噬。
在体内大鼠模型和体外新生CMECs中研究褪黑素对IRI的影响。通过伊文思蓝和氯化三苯基四氮唑染色确定心肌梗死面积。通过细胞活力和乳酸脱氢酶（LDH）释放试验评估细胞损伤的严重程度，并通过透射电子显微镜和自噬相关基因表达评估（如Beclin 1和轻链3-II的表达）来评估自噬。
在体内，褪黑素显著减小梗死面积，改善心脏功能并降低LDH释放。然而，AMPK激活剂AICAR和mTOR抑制剂雷帕霉素降低了褪黑素对IRI的保护作用。在体外，发现Beclin1和轻链3-II蛋白下调，并且自噬体数量因褪黑素而减少，同时细胞活力增加，LDH减少。用AICAR或雷帕霉素处理消除了褪黑素处理所观察到的益处。
褪黑素通过AMPK/mTOR系统抑制自噬抵抗IRI，从而在CMECs中发挥重要的保护作用。
