中文摘要：

目的探讨模拟微重力对PC12细胞衰老的影响及相关机制。方法用旋转细胞培养系统进行模拟微重力条件下的细胞培养。选取模拟微重力和正常重力条件下培养6h，12h，24h，48h，72b和96h的PC12细胞作为研究对象。流式细胞仪检测PC12细胞各个细胞周期分布的变化；Westernblot方法检测PC12细胞P53蛋白的变化；生化反应试剂盒检测活性氧变化；衰老相关B半乳糖苷酶（SA-13-gal）特异性染色对衰老的PC12细胞进行评估。结果细胞周期分析的结果显示，经过模拟微重力培养的PC12细胞其细胞周期阻滞在G1期。在模拟微重力培养96h细胞周期蛋白P53表达均升高。SA—B—gal染色的结果显示在模拟微重力的作用下，PC12细胞SA—B—gal的活性随着模拟微重力培养时间的延长而逐步升高。PC12细胞内H2O2的水平升高，并且具有时间依赖性。模拟微重力细胞培养上清中的H2O2：也相应升高，但是滞后于细胞内的H2O2。结论①模拟微重力可以引起PC12细胞SA-13-g．1的活性升高，G1期细胞周期阻滞和P53的活化；②模拟微重力条件下诱导PC12细胞衰老可能通过氧化应激实现。

英文摘要：

Objective To investigate the effect of simulated microgravity on. cellular senes cence of PC12 cells and its mechanism. Methods The microgravity environment was simula ted by a rotary cell culture system, PC12 cells were cultured under simulated microgravity and normal gravity for6 h, 12 h, 24 h, 48 h, 72 h and96 h. Cell cycle （GO/G1, S, and G2/M） distribution was determined by flow cytometry. P53 protein was detected by Western blot. The activities of n2 02 were detected by chemistry reaction Kit. Senescenceassociated galactosi dase （SA-β-gal） was employed to distinguish the senescentPC12 cells. Results There was a G1 phase arrest in the cell cycle of simulated microgravity cultured PC12 cells. The expressionof P53 was increased on 96 h of microgravity cuhure. The SA-β-galactivity was upregulated with simulated microgravity culture gone on. The amount of H202 was also increased in the sim ulated microgravity cultured PC12 cells in a timedependent manner. Conclusion （1） Simula ted microgravity induces SA-β-gal activity, arrests PC12 ceils in the G1 phase and activates P53 protein; （2） Simulated microgravity promotes PC12 cell senescence probably via oxidant stress.