Repetitive restriction of muscle blood flow enhances mTOR signaling pathways in a rat model
Repetitive restriction of muscle blood flow enhances mTOR signaling pathways in a rat model
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DOI：
10.1007/s00380-016-0801-6
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发表时间：
2016-10-01
影响因子：
1.5
通讯作者：
Kano, Yutaka
中科院分区：
文献类型：
--
作者：
Nakajima, Toshiaki;Yasuda, Tomohiro;Kano, Yutaka
骨骼肌是一种塑料器官，通过影响调节蛋白质合成和降解的途径，使其质量适应各种压力。本研究探讨了重复肌肉血流限制(RRMBF)对大鼠骨骼肌微血管氧分压(PmvO(2))、哺乳动物雷帕霉素靶标(MTOR)信号通路和蛋白降解相关转录本的影响。11周龄雄性Wistar大鼠在麻醉状态下对右侧大腿近端施加6个RMBF，每个RMBF包括100 mm Hg的外力5min，然后休息3min。在RMBF过程中，用磷光猝灭技术测量PmvO(2)。分别于刺激后0~6h取大鼠胫前肌总RNA和总蛋白。Western blotting检测各种信号蛋白的蛋白表达和磷酸化。用实时荧光定量RT-PCR方法检测细胞的mRNA表达水平。RMBF后0h大鼠总肌重增加，但1~6h大鼠无明显变化，RMBF期间PmvO(2)显著下降(36.1+/-5.7至5.9+/-1.7torr)，静息时恢复。刺激后1h，RRMBF显著增加mTOR下游靶蛋白p70S6K和核糖体蛋白S6的磷酸化。Redd1蛋白水平及AMPK和MAPKs的磷酸化水平无明显变化。FOXO3a、MURF-1和myostatin的mRNA表达水平无明显变化。这些结果表明，RRMBF显著降低大鼠骨骼肌PmvO(2)，增强mTOR信号通路，在人体研究中可能在不同条件下起到减轻肌肉萎缩的作用。
Skeletal muscle is a plastic organ that adapts its mass to various stresses by affecting pathways that regulate protein synthesis and degradation. This study investigated the effects of repetitive restriction of muscle blood flow (RRMBF) on microvascular oxygen pressure (PmvO(2)), mammalian target of rapamycin (mTOR) signaling pathways, and transcripts associated with proteolysis in rat skeletal muscle. Eleven-week-old male Wistar rats under anesthesia underwent six RRMBF consisting of an external compressive force of 100 mmHg for 5 min applied to the proximal portion of the right thigh, each followed by 3 min rest. During RRMBF, PmvO(2) was measured by phosphorescence quenching techniques. The total RNA and protein of the tibialis anterior muscle were obtained from control rats, and rats treated with RRMBF 0-6 h after the stimuli. The protein expression and phosphorylation of various signaling proteins were determined by western blotting. The mRNA expression level was measured by real-time RT-PCR analysis. The total muscle weight increased in rats 0 h after RRMBF, but not in rats 1-6 h. During RRMBF, PmvO(2) significantly decreased (36.1 +/- 5.7 to 5.9 +/- 1.7 torr), and recovered at rest period. RRMBF significantly increased phosphorylation of p70 S6-kinase (p70S6k), a downstream target of mTOR, and ribosomal protein S6 1 h after the stimuli. The protein level of REDD1 and phosphorylation of AMPK and MAPKs did not change. The mRNA expression levels of FOXO3a, MuRF-1, and myostatin were not significantly altered. These results suggested that RRMBF significantly decreased PmvO(2), and enhanced mTOR signaling pathways in skeletal muscle using a rat model, which may play a role in diminishing muscle atrophy under various conditions in human studies.