Liu Y, Qi S Y, Ru L S, Ding C, Wang H J, Li A Y, Xu B Y, Zhang G H, Wang D M
Department of Cardiology, Peace Hospital of People's Liberation Army, Shijiazhuang 050082, China.
Zhonghua Xin Xue Guan Bing Za Zhi. 2016 Jun 24;44(6):494-500. doi: 10.3760/cma.j.issn.0253-3758.2016.06.008.
Endoplasmic reticulum (ER) stress plays an important role in ischemia-mediated cell death. The aim of the current study is to investigate the effects of salubrinal (Sal), a selective eIF2a dephosphorylation inhibitor, on heart failure rats and related mechanisms.
Heart failure was induced by coronary artery ligation (MI) in adult male Sprague-Dawley rats. To ensure comparable MI sizes post coronary artery ligation on various groups, echocardiography examination was performed before and 30 minutes after ligation in MI groups. Then rats were randomly assigned to 4 groups: Sham group (n=12), MI group (n=10), MI plus vehicle injections group (DMSO group, n=12) and MI plus Sal injection group (Sal group, n=12). Sal (1 mg/kg) or DMSO was injected via the tail vein daily for the first 3 days (starting at 30 minutes after ligation of the left coronary artery), followed by subcutaneous injections twice per week for 8 weeks. Cardiac function was assessed by echocardiography and cell apoptosis assessed by flow cytometric analysis after 8 weeks. Protein and mRNA levels of ER stress markers were evaluated by immunohistochemistry and real time RT-PCR respectively.
Eight weeks later, LVEF was significantly higher, while LVESD and LVEDD values were significantly lower in Sal group compared to MI and DMSO groups (all P<0.05); LV/BW ratio was significantly higher in MI group than in Sham group ((2.30±0.40) mg/g vs.(1.78±0.31) mg/g, P<0.05), which was significantly reduced in Sal group ((1.88±0.25) mg/g), but not in DMSO group((2.25±0.36) mg/g, P<0.05 vs. MI). In addition, flow cytometric analysis showed that Sal treatment significantly reduced apoptosis but not necrosis in post MI. Immunohistochemistry and real time PCR analysis showed that the myocardial protein and mRNA expression of ER stress markers were significantly lower in Sal group than in MI group, myocardial caspase-12 expression was significantly upregulated in MI group and significantly reduced by Sal treatment.
Our results suggest that reduction of ER stress and myocardial apoptosis through inhibition of eIF2α dephosphorylation may serve as the potential mechanisms for the improved cardiac function and attenuated cardiac remodeling post Sal treatment in this heart failure rat model.
内质网（ER）应激在缺血介导的细胞死亡中起重要作用。本研究旨在探讨选择性eIF2α去磷酸化抑制剂salubrinal（Sal）对心力衰竭大鼠的影响及其相关机制。
采用冠状动脉结扎法（MI）诱导成年雄性Sprague-Dawley大鼠发生心力衰竭。为确保各MI组冠状动脉结扎后梗死面积可比，在MI组结扎前及结扎后30分钟进行超声心动图检查。然后将大鼠随机分为4组：假手术组（n = 12）、MI组（n = 10）、MI加溶剂注射组（二甲基亚砜组，n = 12）和MI加Sal注射组（Sal组，n = 12）。在最初3天（从左冠状动脉结扎后30分钟开始）每天经尾静脉注射Sal（1 mg/kg）或二甲基亚砜，随后每周皮下注射2次，共8周。8周后通过超声心动图评估心功能，通过流式细胞术分析评估细胞凋亡。分别通过免疫组织化学和实时RT-PCR评估ER应激标志物的蛋白质和mRNA水平。
8周后，与MI组和二甲基亚砜组相比，Sal组的左室射血分数（LVEF）显著升高，而左室收缩末期内径（LVESD）和左室舒张末期内径（LVEDD）值显著降低（均P < 0.05）；MI组的左室重量/体重（LV/BW）比值显著高于假手术组（（2.30±0.40）mg/g vs.（1.78±0.31）mg/g，P < 0.05），Sal组该比值显著降低（（1.88±0.25）mg/g），而二甲基亚砜组无明显变化（（2.25±0.36）mg/g，与MI组相比P < 0.05）。此外，流式细胞术分析显示，Sal治疗显著降低MI后细胞凋亡，但不影响坏死。免疫组织化学和实时PCR分析显示，Sal组心肌ER应激标志物的蛋白质和mRNA表达显著低于MI组，MI组心肌半胱天冬酶-12表达显著上调，Sal治疗使其显著降低。
我们的结果表明，在该心力衰竭大鼠模型中，通过抑制eIF2α去磷酸化减轻ER应激和心肌凋亡可能是Sal治疗后心功能改善和心脏重塑减轻的潜在机制。
