Tianjin Cardiovascular Institute, Tianjin Chest Hospital, Tianjin 300222, P.R. China.
Mol Med Rep. 2018 Apr;17(4):5102-5108. doi: 10.3892/mmr.2018.8543. Epub 2018 Feb 2.
To explore the protective effect of N(2)-L-alanyl-L-glutamine (NLAG) on myocardial ischemia-reperfusion injury (IRI), and observe the influence of NLAG on the Janus activated kinase signal transducer 2 and activator of transcription 3 (JAK2/STAT3) signaling pathway‑associated molecules. Wistar rats were randomly divided into three groups: Sham, IRI and NLAG. In the IRI rat model, the cardiac hemodynamics, the maximum rate of left ventricular pressure (+dP/dtmax) and the left ventricular end‑diastolic pressure (LVDP) were recorded. Hematoxylin‑eosin and Masson staining were used to detect myocardial histological changes. The levels of plasma interleukin (IL)‑1β and ‑6, tumor necrosis factor (TNF)‑α, lactase dehydrogenase (LDH), troponin (cTn)I, creatine kinase (CK), heart type fatty acid binding protein (hFABP), malondialdehyde (MDA) and succinate dehydrogenase (SDH) were determined with ELISA. The protein expression levels of B‑cell lymphoma (Bcl)‑2, Bcl2‑associated X protein (Bax), Caspase‑3, JAK2, phosphorylated (p)‑JAK2, STAT3 and p‑STAT3 were detected by western blot analysis. The IRI model demonstrated notable myocardial injury; myocardial cells were arranged disorderly with some nuclei disappearing, and cardiac muscular fibers were degenerated. Following 60 min of reperfusion, LVDP, HR and +dP/dtmax were 31.3±4.53 mmHg, 239.17±8.45 beats/min and 615.17 mmHg/sec, respectively. Compared with the Sham group, the levels of LDH, cTnI, CK, hFABP release, inflammatory factors (IL‑1β, IL‑6 and TNF‑α) and oxygen free radical (MDA and SDH) levels were increased in the IRI group. In the NLAG group, myocardial injury was improved, the concentrations of LDH, cTnI, CK, hFABP, IL‑1β, IL‑6, TNF‑α, MDA were decreased, and SDH release was increased compared with the IRI group. In addition, NLAG significantly increased Bcl‑2, JAK2, p‑JAK2, STAT3 and p‑STAT3 protein expression, and decreased Bax protein expression compared with the IRI group. In conclusion, myocardial ischemia‑reperfusion can lead to myocardial cell apoptosis and myocardial injury and NLAG attenuates the IRI‑induced mitochondrial oxidative stress injury and apoptosis by activating the JAK2/STAT3 signaling pathway, thus exerting protective effects against IRI.
探讨 N（2）-L-丙氨酰-L-谷氨酰胺（NLAG）对心肌缺血再灌注损伤（IRI）的保护作用，并观察 NLAG 对 Janus 激活激酶信号转导子和转录激活子 3（JAK2/STAT3）信号通路相关分子的影响。
将 Wistar 大鼠随机分为三组：假手术组（Sham）、IRI 组和 NLAG 组。在 IRI 大鼠模型中，记录心脏血流动力学、左心室压力最大上升速率（+dP/dtmax）和左心室舒张末期压（LVDP）。苏木精-伊红和 Masson 染色检测心肌组织学变化。采用酶联免疫吸附试验（ELISA）测定血浆白细胞介素（IL）-1β和 -6、肿瘤坏死因子（TNF）-α、乳酸脱氢酶（LDH）、肌钙蛋白（cTn）I、肌酸激酶（CK）、心脏型脂肪酸结合蛋白（hFABP）、丙二醛（MDA）和琥珀酸脱氢酶（SDH）水平。采用 Western blot 分析检测 B 细胞淋巴瘤（Bcl）-2、Bcl2 相关 X 蛋白（Bax）、半胱天冬酶-3、JAK2、磷酸化（p）-JAK2、STAT3 和 p-STAT3 的蛋白表达水平。
IRI 模型显示出明显的心肌损伤；心肌细胞排列紊乱，部分细胞核消失，心肌纤维变性。再灌注 60 min 后，LVDP、HR 和 +dP/dtmax 分别为 31.3±4.53 mmHg、239.17±8.45 次/分钟和 615.17 mmHg/秒。与 Sham 组相比，IRI 组 LDH、cTnI、CK、hFABP 释放、炎症因子（IL-1β、IL-6 和 TNF-α）和氧自由基（MDA 和 SDH）水平升高。在 NLAG 组中，与 IRI 组相比，心肌损伤得到改善，LDH、cTnI、CK、hFABP、IL-1β、IL-6、TNF-α、MDA 浓度降低，SDH 释放增加。此外，与 IRI 组相比，NLAG 显著增加了 Bcl-2、JAK2、p-JAK2、STAT3 和 p-STAT3 蛋白表达，降低了 Bax 蛋白表达。
心肌缺血再灌注可导致心肌细胞凋亡和心肌损伤，NLAG 通过激活 JAK2/STAT3 信号通路减轻 IRI 诱导的线粒体氧化应激损伤和细胞凋亡，从而发挥对 IRI 的保护作用。
