Boccalini Giulia, Sassoli Chiara, Formigli Lucia, Bani Daniele, Nistri Silvia
Department of Experimental and Clinical Medicine, Section of Anatomy and Histology, Research Unit of Histology and Embryology, University of Florence, Florence, Italy.
Department of Experimental and Clinical Medicine, Section of Anatomy and Histology, Research Unit of Histology and Embryology, University of Florence, Florence, Italy
FASEB J. 2015 Jan;29(1):239-49. doi: 10.1096/fj.14-254854. Epub 2014 Oct 23.
In animal models, the cardiotropic hormone relaxin has been shown to protect the heart against ischemia and reperfusion-induced damage, acting by multiple mechanisms that primarily involve the coronary vessels. This in vitro study evaluates whether relaxin also has a direct protective action on cardiac muscle cells. H9c2 rat cardiomyoblasts and primary mouse cardiomyocytes were subjected to hypoxia and reoxygenation. In some experiments, relaxin was added preventatively before hypoxia; in others, at reoxygenation. To elucidate its mechanisms of action, we focused on Notch-1, which is involved in heart pre- and postconditioning to ischemia. Inactivated RLX was used as negative control. Relaxin (17 nmol/L, EC50 4.7 nmol/L), added 24 h before hypoxia or at reoxygenation, protected against cardiomyocyte injury. In fact, relaxin significantly increased cell viability (assayed by trypan blue and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide), decreased apoptosis (assayed by TUNEL and bax/bcl-2 ratio), and reduced nitroxidative damage (assayed by nitrotyrosine expression and 8-hydroxy-deoxyguanosine levels). These effects were partly attributable to the ability of relaxin to upregulate Notch-1 signaling; indeed, blockade of Notch-1 activation with the specific inhibitor DAPT reduced relaxin-induced cardioprotection during hypoxia and reoxygenation. This study adds new mechanistic insights on the cardioprotective role of relaxin on ischemic and oxidative damage.
在动物模型中，心脏营养激素松弛素已被证明可保护心脏免受缺血和再灌注诱导的损伤，其作用机制主要涉及冠状动脉血管的多种机制。这项体外研究评估松弛素是否也对心肌细胞具有直接保护作用。将H9c2大鼠心肌成纤维细胞和原代小鼠心肌细胞置于缺氧和复氧环境中。在一些实验中，在缺氧前预防性添加松弛素；在另一些实验中，在复氧时添加。为阐明其作用机制，我们聚焦于参与心脏缺血预处理和后处理的Notch-1。将失活的松弛素用作阴性对照。在缺氧前24小时或复氧时添加的松弛素（17 nmol/L，半数有效浓度4.7 nmol/L）可保护心肌细胞免受损伤。事实上，松弛素显著提高了细胞活力（通过台盼蓝和3-(4,5-二甲基噻唑-2-基)-2,5-二苯基溴化四氮唑测定），降低了细胞凋亡（通过末端脱氧核苷酸转移酶介导的缺口末端标记法和bax/bcl-2比值测定），并减少了氮氧化损伤（通过硝基酪氨酸表达和8-羟基脱氧鸟苷水平测定）。这些作用部分归因于松弛素上调Notch-1信号传导的能力；确实，用特异性抑制剂DAPT阻断Notch-1激活可降低松弛素在缺氧和复氧期间诱导的心脏保护作用。这项研究为松弛素对缺血和氧化损伤的心脏保护作用增添了新的机制见解。
