The purpose of this study was to determine whether sarcopenic obesity accelerates impairments in muscle maintenance through the investigation of cell cycle progression and myogenic, inflammatory, catabolic and protein synthetic signaling in mouse gastrocnemius muscles. At 4 weeks old, 24 male C57BL/6 mice were fed either a high fat diet (HFD, 60 % fat) or normal chow (NC, 17 % fat) for either 8–12 weeks or 21–23 months. At 3−4 months or 22−24 months the gastrocnemius muscles were excised. In addition, plasma was taken for C2C12 differentiation experiments. Mean cross-sectional area (CSA) was reduced by 29 % in aged HFD fed mice compared to the aged NC mice. MyoD was roughly 50 % greater in the aged mice compared to young mice, whereas TNF-α and IGF-1 gene expression in aged HFD fed mice were reduced by 52 % and 65 % in comparison to aged NC fed mice, respectively. Myotubes pretreated with plasma from aged NC fed mice had 14 % smaller myotube diameter than their aged HFD counterparts. Aged obese mice had greater impairments to mediators of muscle maintenance as evident by reductions in muscle mass, CSA, along with alterations in cell cycle regulation and inflammatory and insulin signaling.

本研究的目的是通过研究小鼠腓肠肌中的细胞周期进程和生肌、炎症、分解代谢和蛋白质合成信号传导，确定肌肉减少性肥胖是否会加速肌肉维持的损伤。在 4 周大时，24 只雄性 C57BL/6 小鼠被喂食高脂肪饮食（HFD，60% 脂肪）或正常食物（NC，17% 脂肪）8-12 周或 21-23 个月。在 3-4 个月或 22-24 个月时切除腓肠肌。此外，取血浆进行 C2C12 分化实验。与老年 NC 小鼠相比，老年 HFD 喂养小鼠的平均横截面积 (CSA) 减少了 29%。与年轻小鼠相比，老年小鼠的 MyoD 大约高出 50%，而与老年 NC 喂养小鼠相比，老年 HFD 喂养小鼠的 TNF-α 和 IGF-1 基因表达分别降低了 52% 和 65%。用来自老年 NC 喂养小鼠的血浆预处理的肌管的肌管直径比其老年 HFD 对应物小 14%。老年肥胖小鼠对肌肉维持介质的损害更大，这可以通过肌肉质量、CSA 的减少以及细胞周期调节以及炎症和胰岛素信号传导的改变来证明。