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目的:探讨NF-κB在不同电刺激状态下C2C12肌管粒体功能低下时的作用。方法:采用TY-C型电刺激器(强度为45 V、20 ms、5 Hz)刺激分化6天的C2C12肌管来建立耐力运动时的神经冲动模型,对照组无任何电刺激,实验组分为刺激即刻组、孵育组和对照组,刺激即刻组的刺激时间分别为60分钟、75分钟、90分钟、120分钟、150分钟和180分钟,孵育组刺激120分钟后放入培养箱中继续培养,时间分别为30分钟、60分钟、120分钟和180分钟。测定各组细胞pIKK-α、NF-κB及MnSOD活性变化。结果:与对照组相比,电刺激即刻组C2C12细胞NF-κB活性显著升高(P<0.01),且刺激120分钟和150分钟增加明显(P<0.05),到180分钟时,略有下降。孵育组中孵育120分钟时NF-κB活性较孵育组其它细胞显著增加(P<0.01);与对照组相比,刺激即刻各组细胞内pIKK-α表达显著增加(P<0.05),但不同时间电刺激各组之间无显著差别。孵育组中,孵育120分钟细胞pIKK-α蛋白表达与孵育组其他细胞相比显著升高(P<0.01);与对照组相比,刺激即刻组刺激150分钟时细胞线粒体MnSOD活性显著增加(P<0.01),孵育组孵育120分钟时C2C12细胞线粒体MnSOD活性显著增加(P<0.01)。结论:(1)在电刺激引起C2C12细胞产生氧化应激,导致细胞线粒体功能的下降中,内源性ROS的产生会激活NF-κB的表达,同时激活IKK-α的磷酸化,且在电刺激强度一定时,NF-κB的活性对电刺激的应答有一定的时相性。(2)随着刺激时间的不同,细胞线粒体MnSOD的活性变化有差异,且线粒体MnSOD活性的变化与刺激时间有关,推测NF-κB的表达上调了细胞内抗氧化物酶MnSOD的表达,这在一定程度上对细胞起到保护作用。
Objective: To investigate the role of NF-κB in C2C12 myofibroblasts under different electrical stimulation. Methods: The model of nerve impulses during endurance exercise was established by stimulation of C2C12 myotubes with TY-C electrical stimulator (intensity: 45 V, 20 ms, 5 Hz) for 6 days. The control group received no electrical stimulation. In order to stimulate the immediate group, the incubation group and the control group, the stimulating time of the immediate group was 60 minutes, 75 minutes, 90 minutes, 120 minutes, 150 minutes and 180 minutes respectively. The stimulation group was incubated for 120 minutes in the incubator, , The time was 30 minutes, 60 minutes, 120 minutes and 180 minutes. The changes of pIKK-α, NF-κB and MnSOD in each group were measured. Results: Compared with the control group, the activity of NF-κB in C2C12 cells was significantly increased (P <0.01) and increased significantly at 120 and 150 minutes (P <0.05), and slightly decreased at 180 minutes . Compared with the control group, the expression of pIKK-α in each group increased significantly (P <0.05), while the difference was not significant Time electrical stimulation between the groups no significant difference. Compared with the control group, the mitochondrial MnSOD activity increased significantly (P <0.01) after stimulated for 150 minutes in the immediate group compared with the control group <0.01). The mitochondrial MnSOD activity of C2C12 cells increased significantly (P <0.01) at 120 min after incubation. Conclusions: (1) In electrical stimulation, C2C12 cells produce oxidative stress, which leads to the decrease of mitochondrial function. The production of endogenous ROS activates the expression of NF-κB and activates the phosphorylation of IKK-α, When stimulus intensity is certain, the response of NF-κB to electrical stimulation has a certain phase. (2) The changes of mitochondrial MnSOD activity varied with the stimulation time, and the change of mitochondrial MnSOD activity was related to the stimulation time. It was speculated that the expression of NF-κB upregulated the expression of intracellular antioxidant enzyme MnSOD To a certain extent, play a protective role on the cells.