Food Microbiology and Function Research Laboratories, R&D Division, Meiji Co., Ltd, Hachiouji, Tokyo, Japan.
Department of Exercise Physiology, Nippon Sports Science University, Setagaya-ku, Tokyo, Japan.
Exp Physiol. 2020 Jul;105(7):1111-1123. doi: 10.1113/EP088622. Epub 2020 Jun 8.
What is the central question of this study? Is stretch-shortening contraction effective to attenuate skeletal muscle atrophy and hepatic dysfunction in a rat model of peptidoglycan-polysaccharide (PG-PS)-induced inflammation (PG-PS rat)? What are the main findings and their importance? Stretch-shortening contraction attenuates skeletal muscle atrophy in the trained leg and increases circulating interleukin-10 in PG-PS rats. Stretch-shortening contraction also ameliorates liver dysfunction in PG-PS rats, possibly via increased blood interleukin-10. These findings are important because they suggest that stretch-shortening contraction is effective to maintain liver function in addition to exercised skeletal muscle mass.
Stretch-shortening contraction (SSC) is an effective modality to improve skeletal muscle mass. However, the beneficial effects of SSC in the presence of chronic inflammation remain unclear. Here, we imposed five SSC sessions unilaterally on the triceps surae in young female Lewis rats. Rats were injected with vehicle or peptidoglycan-polysaccharide (PG-PS) to induce long-lasting inflammation. The PG-PS reduced gastrocnemius muscle mass in both legs, but that of the SSC-trained leg was significantly greater than that of the contralateral leg. Circulating pro-inflammatory cytokines, such as IL-1β, were significantly increased by PG-PS injection, even if carrying out SSC. The circulating anti-inflammatory cytokine IL-10 increased with SSC in both healthy and inflammatory conditions. Stretch-shortening contraction also prevented increases in serum aspartate aminotransferase activity and plasma free phenylalanine concentration induced by PG-PS, in comparison to the control resistance exercise consisting of isometric contractions. Moreover, aspartate aminotransferase and phenylalanine concentrations demonstrated a significant and negative correlation with IL-10/IL-1β values (r = -0.61, P = 0.017, and r = -0.66, P = 0.008, respectively). These results suggest that SSC training is effective to reduce both muscle atrophy and the hepatic dysfunction induced by PG-PS, mediated, at least in part, through an increase in circulating IL-10.
本研究的核心问题是什么？在肽聚糖-多糖（PG-PS）诱导的炎症大鼠模型中，伸展-缩短收缩（SSC）是否能有效减轻骨骼肌萎缩和肝功能障碍？主要发现及其重要性是什么？SSC 可减轻训练侧肢体的骨骼肌萎缩，并增加 PG-PS 大鼠的循环白细胞介素-10（IL-10）。SSC 还可改善 PG-PS 大鼠的肝功能障碍，可能是通过增加血液中白细胞介素-10（IL-10）实现的。这些发现很重要，因为它们表明 SSC 除了能增加运动骨骼肌质量外，还能有效维持肝功能。
伸展-缩短收缩（SSC）是一种有效改善骨骼肌质量的方法。然而，在存在慢性炎症的情况下，SSC 的有益作用尚不清楚。在此，我们在年轻雌性 Lewis 大鼠的比目鱼肌上进行了 5 次单侧 SSC。大鼠注射载体或肽聚糖-多糖（PG-PS）以诱导长期炎症。PG-PS 降低了双侧腓肠肌的质量，但 SSC 训练侧的质量明显大于对侧。PG-PS 注射会显著增加循环促炎细胞因子（如白细胞介素-1β（IL-1β）），即使进行 SSC 也是如此。在健康和炎症状态下，IL-10 都会随 SSC 而增加。与对照阻力运动（等长收缩）相比，SSC 还可防止 PG-PS 引起的血清天冬氨酸氨基转移酶（AST）活性和血浆游离苯丙氨酸浓度的升高。此外，AST 和苯丙氨酸浓度与 IL-10/IL-1β 值呈显著负相关（r = -0.61，P = 0.017 和 r = -0.66，P = 0.008）。这些结果表明，SSC 训练可有效减轻 PG-PS 诱导的肌肉萎缩和肝功能障碍，至少部分通过增加循环白细胞介素-10（IL-10）来介导。
