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我们前期研究表明胰岛素可激活细胞内信号转导机制如磷脂酰肌醇3-激酶-蛋白激酶B-内皮型一氧化氮合酶-一氧化氮(PI3-K-Akt-eNOS-NO)信号通路,减轻心肌缺血/再灌注(ischemia/reperfusion,I/R)损伤,改善缺血后心肌功能恢复。然而c-Jun氨基末端激酶(c-Jun NH2-terminal kinase,JNK)信号通路在胰岛素保护I/R心肌中的作用尚不清楚,本研究旨在探讨JNK信号通路在胰岛素保护I/R心肌中的作用及其与PI3-K/Akt信号通路间的相互关系。离体Sprague-Dawley大鼠心脏缺血30min后施行2h或4h的再灌注,缺血前用LY294002(15mmol/L)和SP600125(10mmol/L)灌注15min,分别阻断PI3-K/Akt和磷酸化JNK(phosphorylated-JNK,p-JNK)活化,观测心脏功能、心肌梗死、细胞凋亡和蛋白磷酸化水平。与对照组相比,胰岛素再灌注2h后,心率、左心室发展压和左心室收缩/舒张最大速率均明显增加,梗死面积减少约16.1%[(28.9±2.0)%vs(45.0±4.0)%,n=6,P<0.01],细胞凋亡指数从(27.6±1.3)%减少到(16.0±0.7)%(n=6,P<0.01),Akt的活性增加1.7倍(n=6,P<0.05),同时JNK活性增加1.5倍(n=6,P<0.05)。用LY294002处理后,胰岛素对I/R心肌的保护作用消失;而用SP600125处理可增强胰岛素的保护作用,且可部分逆转LY294002的抑制作用。进一步观察发现SP600125减弱了Akt的磷酸化(n=6,P<0.05)。上述结果表明,在I/R心肌中,胰岛素可同时激活PI3-K/Akt及JNK信号通路,且通过后者进一步增加Akt活化,从而减轻I/R损伤,改善心肌功能。这种PI3-K/Akt与JNK信号通路交互机制对胰岛素保护I/R心肌有重要意义。
Our previous studies showed that insulin can activate intracellular signal transduction mechanisms such as PI3-K-Akt-eNOS-NO signaling pathway , Reduce the damage of myocardial ischemia / reperfusion (I / R) and improve the recovery of myocardial function after ischemia. However, the role of c-Jun N-terminal kinase (JNK) signaling pathway in insulin-protected I / R myocardium is unclear. This study aimed to investigate the role of JNK signaling pathway in insulin-protected I / R myocardium And its relationship with the PI3-K / Akt signaling pathway. The hearts of isolated Sprague-Dawley rats were reperfused for 2h or 4h after ischemia for 30min, and pretreated with LY294002 (15mmol / L) and SP600125 (10mmol / L) for 15min before ischemia, respectively. PI3-K / Activation of phosphorylated-JNK (p-JNK), cardiac function, myocardial infarction, apoptosis and protein phosphorylation were observed. Compared with the control group, heart rate, left ventricular systolic pressure and maximal rate of left ventricular systolic / diastolic were significantly increased 2 h after reperfusion of insulin, infarct size decreased by 16.1% [(28.9 ± 2.0)% vs (45.0 ± 4.0)% (n = 6, P <0.01). The apoptotic index decreased from (27.6 ± 1.3)% to (16.0 ± 0.7)% P <0.05), while JNK activity increased by 1.5 times (n = 6, P <0.05). After treatment with LY294002, the protective effects of insulin on I / R myocardium disappeared; however, the treatment with SP600125 could enhance the protective effect of insulin and partially reverse the inhibitory effect of LY294002. Further observation revealed that SP600125 attenuated Akt phosphorylation (n = 6, P <0.05). The above results indicate that insulin can activate PI3-K / Akt and JNK signaling pathways in I / R myocardium, and further increase Akt activation through I / R myocardium, thereby reducing I / R injury and improving myocardial function. This interaction between PI3-K / Akt and JNK signaling pathway is important for the insulin protection of I / R myocardium.