8周间歇运动激活LIF-LIFR-STAT3信号和诱导骨骼肌细胞增殖
Eight-Week Interval Exercise Activates LIF-LIFR-STAT3 Signaling and Promotes Muscle Cell Proliferation in Rats

摘要：目的：探讨间歇运动对大鼠骨骼肌细胞增殖和白血病抑制因子（Leukemia inhibitory factor，LIF）及其下游信号分子表征的影响。方法：3月龄雄性SD大鼠，随机分为安静对照组（C）、间歇运动组（CE），每组15只。运动组采用小动物跑台运动，先以10 m/min×10 min，再以25 m/min×7 min和15 m/min×3 min，依次交替，60 min/d，5d/周×8 周。运动结束后次日，分离切取腓肠肌组织，称重。组织学方法测定腓肠肌细胞横截面积（Cross-section area，CSA），RT-qPCR检测腓肠肌LIF/LIFR mRNA水平，Western blot检测腓肠肌LIF及其受体（Leukemia inhibitory factor receptor，LIFR）、信号转导与转录激活因子（signal transducer and activator of transcription，STAT3）及其磷酸化水平（p-STAT3）和增殖细胞核抗原（proliferating cell nuclear antigen，PCNA）蛋白表达，免疫荧光化学观察分析腓肠肌LIF、LIFR、PCNA和细胞增殖抗原标记物（ki67）表达。结果：与C组比较，CE组大鼠腓肠肌重量和细胞横截面积增大（P<0.01），LIF/LIFR基因和蛋白表达均显著增加（P<0.01，P<0.05），STAT3磷酸化水平显著升高（P<0.01），PCNA和ki67蛋白表达显著增加（P<0.01）。结论：8周间歇运动可促进正常大鼠骨骼肌细胞肥大，激活LIF-LIFR-STAT3信号通路，诱导骨骼肌细胞增殖。运动干预骨骼肌LIF表征的研究，可为进一步探讨运动诱导骨骼肌肥大机制和预防骨骼肌丢失与萎缩提供实验依据。
Abstract: Objectives: The objective of this study was to determine the effects of interval exercise on cell proliferation of skeletal muscle, expression of leukemia inhibitory factor (LIF) and leukemia inhibitory factor receptor (LIFR) in rat. Methods: Three-month old male sprague-dawley rats were randomly divided into two groups (n=15): the sedentary group (Control) and interval aerobic exercise group (CE). The CE group rats was initiated at 10 m/min for 10 min, and then alternated between 7 min at 25 m/min and 3 min at 15 m/min, 60 min per day, 5 days per week, and 8 weeks in total. All rats’ gastrocnemius was dissected on the next day after 8-week interval training and its weight was tested. The cross-section area (CSA) of gastrocnemius cells was tested by histological method, the LIF/LIFR mRNA expression was measured by RT-qPCR, the expressions of LIF and LIFR, signal transducer and activator of transcription (STAT3), p-STAT3 and proliferating cell nuclear antigen (PCNA) were detected by Western Blot and the expressions of LIF, LIFR, PCNA and ki67 were observed by immunofluorescence. Results: Compared with C group, the weight and cell CSA of gastrocnemius muscle, mRNA and protein expressions of LIF/LIFR, p-STAT3 level, PCNA and ki67 expressions of CE group were higher (Ps < 0.05). Conclusion: Eight-week interval exercise cound promote hypertrophy of skeletal muscle cells in rats, activate LIF-LIFR-STAT3 signaling pathway and reduce cell proliferation of skeletal muscles. This study provided an experimental basis for further study on the mechanism of exercise-induced skeletal muscle hypertrophy and the prevention of skeletal muscle loss and atrophy