胰岛素样生长因子Ⅰ对大鼠缺血缺氧心肌细胞凋亡的影响

目的 了解胰岛素样生长因子I(IGF-I)对缺血缺氧致心肌细胞凋亡的影响,探讨其调控机制.方法 分离培养SD乳鼠的心肌细胞.于制备缺血缺氧心肌细胞模型(缺血缺氧组)前1 h,用IGF-I(200μg/L)进行干预(干预组),以缺血缺氧组致伤前测定结果为正常对照(对照组).观察不同时相点心肌细胞凋亡的吸光度(A)值、线粒体膜电位变化及磷酸化Akt蛋白表达变化.结果 对照组心肌细胞凋亡A值为0.18±0.03;缺血缺氧后1、3、6、12 h分别为0.33±0.05、0.61 ±0.06、1.17±0.08、2.25±0.11,与对照组比较,差异有统计学意义(P＜0.01);干预组上述时相点的A值分别为0.26±0.04、0.49±0.05、0.84±0.06、1.63±0.09,与缺血缺氧组比较差异有统计学意义(P＜0.05或P＜0.01).缺血缺氧6、12 h,心肌细胞线粒体膜电位荧光强度较对照组40.2±10.1下降,分别为18.7±5.1、6.3±1.9(P＜0.01),干预组较缺血缺氧组相对增高,分别为28.8±6.2、12.5±3.1(P＜0.05).与对照组比较,其余各组缺血缺氧后6 h磷酸化Akt蛋白表达量增加.结论 IGF-I对缺血缺氧心肌细胞具有抗凋亡作用,其机制可能与IGF-I激活磷脂酰肌醇3-激酶/Akt、增加磷酸化Akt表达、减少细胞色素c的释放有关.

The influence of insulin growth factor-I on the apoptosis of cardiomyocytes subjected to ischemia and hypoxia

OBJECTIVE: To investigate the influence of insulin growth factor-I (IGF-I) on apoptosis of cardiomyocytes subjected to ischemia and hypoxia and its possible mechanism. METHODS: Cardiomyocytes were cultured in vitro, and randomized into hypoxia group, treatment group (T, the cells were treated with IGF-1 before subjected to hypoxia and ischemia) and control group (C, normal cardiomyocytes as controls). Changes in the OD value of cell apoptosis, mitochondrial membrane potential and relative amount of phospho-Akt protein were observed at different time-points by ELISA, laser scanning with TMRE staining and Western blot, respectively. RESULTS: The OD value of cell apoptosis in control group was 0.18 +/- 0.03, while that in hypoxia group was gradually increased to 0.33 +/- 0.05, 0.61 +/- 0.06, 1.17 +/- 0.08, 2.25 +/- 0.11, respectively at 1, 3, 6, 12 post-hypoxia hours (PHH), showing an increasing tendency (P < 0.01). The OD values of cell apoptosis in T group were 0.26 +/- 0.04, 0.49 +/- 0.05, 0.84 +/- 0.06, 1.63 +/- 0.09, respectively, which were obviously lower than those in hypoxia group (P < 0.05 or P < 0.01). The mitochondrial membrane potential (Dymt) values in hypoxia group at 6 and 12 PHH were 18.7 +/- 5.1 and 6.3 +/- 1.9, respectively, which were obviously lower than that in control group (40.2 +/- 10.1, P < 0.01). The DYmt in T group at 6 and 12 PHH were 28.8 +/- 6.2, 12.5 +/- 3.1, respectively, which were obviously higher compared with those in hypoxia group (P < 0.05). The amount of phospho-Akt protein was increased by IGF-I administration. CONCLUSION: IGF-I exhibits an anti-apoptotic effect on cardiomyocytes subjected to ischemia and hypoxia, and this may be related to the activation of PI3K/Akt signal pathway and stabilization of mitochondrial membrane potential.