Guilu Erxian Jiao (GEJ) is a commonly used nutritional supplement due to its rich content of amino acids. It is also a traditional herbal medicine for improving degenerative joint. This study aimed to investigate the effect and mechanism of GEJ water extract (GEJ-WE) on skeletal muscle in C2C12 myotubes and C57BL/6J mice. Analysis of GEJ-WE were performed by high-performance liquid chromatography fingerprinting with chemical standards. Protein expression, mRNA level, glycogen content, mitochondria activity and ATP level were evaluated by western blots, real-time PCR, PAS staining, MTT and ATP bioluminescence assay, respectively. Skeletal muscle strength was evaluated by grip strength. Skeletal muscle volume, mass and fiber types were evaluated by micro computed tomography, histological analysis and immunofluorescence staining, respectively. Motor function was evaluated by rotarod performance and locomotor activity. In C2C12 myotubes, GEJ-WE significantly enhanced myogenic differentiation and myotube growth, protein synthesis signaling IGF-1/IGF-1R/IRS-1/Akt, Glut4 translocation, glycogen content, mitochondrial biogenesis signaling PGC-1α/NRF1/TFAM, mitochondrial activity and ATP production. However, IGF-1R antagonist AG1024 and PI3K inhibitor wortmannin reduced GEJ-WE-induced protein expression of MyHC, p-Akt, p-mTOR and p-GSK-3β, Glut4 translocation and glycogen content. In C57BL/6J mice, GEJ-WE not only upregulated protein synthesis and mitochondrial biogenesis signaling, but it also increased muscle volume, relative muscle weight, cross-sectional area of myofibers, glycogen content and transition of fast-to-slow type fibers of skeletal muscles. Moreover, GEJ-WE enhanced grip strength and motor activity of mice. In conclusion, the upregulation of protein synthesis, myogenic differentiation, glucose homeostasis, mitochondrial biogenesis and slow-twitch fibers contributes to the mechanisms of GEJ-WE on the enhancement of skeletal muscle mass and motor function.

中文翻译：

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龟鹿二仙胶可增强骨骼肌中的蛋白质合成、葡萄糖稳态、线粒体生物发生和慢肌纤维。

龟鹿二仙胶 (GEJ) 是一种常用的营养补充剂，因为它含有丰富的氨基酸。它也是一种改善退行性关节的传统草药。本研究旨在探讨 GEJ 水提取物 (GEJ-WE) 对 C2C12 肌管和 C57BL/6J 小鼠骨骼肌的影响和机制。GEJ-WE 的分析通过高效液相色谱指纹图谱与化学标准进行。蛋白质表达、mRNA 水平、糖原含量、线粒体活性和 ATP 水平分别通过蛋白质印迹、实时 PCR、PAS 染色、MTT 和 ATP 生物发光测定法进行评估。通过握力评估骨骼肌力量。分别通过显微计算机断层扫描、组织学分析和免疫荧光染色评估骨骼肌体积、质量和纤维类型。通过旋转杆性能和运动活动评估运动功能。在 C2C12 肌管中，GEJ-WE 显着增强了肌源性分化和肌管生长、蛋白质合成信号 IGF-1/IGF-1R/IRS-1/Akt、Glut4 易位、糖原含量、线粒体生物合成信号 PGC-1α/NRF1/TFAM、线粒体活动和 ATP 生产。然而，IGF-1R 拮抗剂 AG1024 和 PI3K 抑制剂渥曼青霉素降低了 GEJ-WE 诱导的 MyHC、p-Akt、p-mTOR 和 p-GSK-3β 蛋白表达、Glut4 易位和糖原含量。在 C57BL/6J 小鼠中，GEJ-WE 不仅上调蛋白质合成和线粒体生物发生信号，而且还增加肌肉体积、相对肌肉重量、肌纤维横截面积、糖原含量和快到慢型纤维的转换骨骼肌。而且，GEJ-WE 增强了小鼠的握力和运动活动。总之，蛋白质合成、成肌分化、葡萄糖稳态、线粒体生物发生和慢肌纤维的上调有助于 GEJ-WE 增强骨骼肌质量和运动功能的机制。