神经肌肉电刺激对低O_2高CO_2大鼠下肢骨骼肌miR-1相关通路的影响

Effects of neuromuscular electrical stimulation on lower muscle of hypoxia-hypercapnia rats via regulation of miR1-related signaling pathway

目的:探讨神经肌肉电刺激(NMES)对慢性低O_2高CO_2大鼠腓肠肌的作用,并研究其对miR-1及相关蛋白通路的影响。方法:成年SD大鼠24只随机分成3组:对照组(NC组)、造模组(HH组)和电刺激组(HE 组),每组8只。HH组和HE组大鼠置于低O_2高CO_2舱内造模,每天持续8h,共4周。HE组在持续造模2周后,用电刺激仪对大鼠进行30min,2Hz和100 Hz,1:1交替循环模式的NMES,维持2周;NC组仅做捆绑及贴电极片处理。动物跑台测定大鼠耐力运动能力,免疫组织化学观察腓肠肌肌纤维类型转变,q RT-PCR检测miR-1水平,Western blot检测腓肠肌核内组蛋白脱乙酰基酶4(HDAC4)、肌细胞促进因子2(MEF-2)和过氧化体增殖物激活型受体γ共激活因子1α(PGC-1α)蛋白含量的变化。结果:与NC组比,HH组大鼠腓肠肌慢肌纤维比例明显下降,mi R-1含量明显升高,HDAC4、MEF2及PGC-1α蛋白含量明显下降,差异均有统计学意义(P<0.05);大鼠耐力运动能力差异无统计学意义(P=0.054);与HH组比,HE组大鼠腓肠肌慢肌纤维比例明显升高,而miR-1含量下降,对应各蛋白含量均出现不同程度升高,大鼠耐力运动能力也得到了改善,差异均有统计学意义(P<0.05)。结论:慢性低O_2高CO_2可致大鼠腓肠肌慢肌纤维向快肌纤维转变,从而导致运动耐力下 降,而NMES可部分逆转这种病理变化,改善大鼠耐力运动能力。mi R-1-HDAC4-MEF2-PGCα信号通路可能参与其中。

Objective： To explore the effects of neuromuscular electrical stimulation on gastrocnemius muscle of chronic intermittent hypoxia-hypercapnia （C1HH） rats and try to find out how much the miR-1 related signaling pathway is involved in. Methods： Twenty four male SD rats were randomly divided into three groups： the normal control group （NC）, hypoxia-hypercapnia group （HH）, hypoxia-hypercapnia＋electrical stimulation group （HE）. The HH and HE were placed in a chamber with hypoxia-hypercapnia for 8 h/d, 4 weeks in all. After 2 weeks, 30 min, 2 Hz and 100 Hz, 1：1 cyclic alternating pattern of electrical stimulation was applied in the HE, which lasted 2 weeks. The NC was only tied up and placed with electrode plates. The endurance running capacity was assessed by the treadmill. The muscle phenotype was observed by immunohistochemical staining. The expression of miR- 1 by qRT-PCR was detected. The expression of HDAC4 （histone deacetylase 4）, MEF2 （myocyte enhancer factor 2） and PGC-1α were detected by Western blot. Results; After 4 weeks, the HH group exhibited a decreased MHCI-to-MHCII shift （P〈0.05）. Nuclear HDAC4, MEF2 and PGC-1α was also significantly decreased （P〈0.05）. In contrast, miR-1 was significantly increased （P〈0.05）. Electrical stimulation can partly reversed those changes, and improved endurance running capacity. Conclusion： Our study indicate the miR-1 related signaling pathway may play a role in the response of CIHH-impaired muscle to changes during electrical stimulation.