Consecutive bouts of electrical stimulation-induced contractions alter ribosome biogenesis in rat skeletal muscle
Consecutive bouts of electrical stimulation-induced contractions alter ribosome biogenesis in rat skeletal muscle
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DOI：
10.1152/japplphysiol.00665.2018
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发表时间：
2019-06-01
影响因子：
3.3
通讯作者：
Ishii, Naokata
中科院分区：
文献类型：
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作者：
Kotani, Takaya;Takegaki, Junya;Ishii, Naokata
核糖体生物合成与抗阻运动训练（RET）诱导的骨骼肌肥大有关。然而，目前尚不清楚RET的增加如何影响核糖体含量和生物发生。这是在本研究中使用模拟RET大鼠骨骼肌受到越来越多的电刺激。将SD大鼠随机分为7组：安静5天组（SED）、安静6周组（SED_6w）、抗阻运动1次组（1B）、抗阻运动2次组（2B）。3回合（3B）、6回合（6 B）和18回合（18 B）。在异氟醚麻醉下，通过经皮电刺激右侧腓肠肌模拟RET，每周进行3次RET。1B、2B和3B组大鼠每单位肌肉重量的45 S前体（前）rRNA和18 S +28 S rRNA含量增加，c-myc和上游结合因子（UBF）mRNA水平升高。RET后48 h，磷酸化UBF和总细胞周期蛋白D1蛋白水平增加;前者增加作为RET持续时间的函数。在3B、6 B和18 B组中，单位肌肉重量的18 S +28 S rRNA含量保持不变，而18 B组的45 S pre-rRNA、cyclin D1和磷酸化UBF水平低于3B组。这些结果表明，RET激活核糖体的生物合成和增加核糖体含量通过调节UBF和细胞周期蛋白D1的活性在其早期阶段。额外的RET可能不会通过可能的转录过程的衰减导致单位肌肉重量的核糖体含量的进一步增加。新&值得注意的是核糖体生物合成与抗阻运动训练诱导的骨骼肌肥大有关。然而，目前还不清楚这是如何影响的阻力运动训练的重复回合的量。利用大鼠骨骼肌抗阻运动训练模型，我们提供的证据表明，核糖体生物合成刺激的最初几回合的抗阻运动训练，没有额外的影响，进一步增加运动回合。
Ribosome biogenesis has been implicated in resistance exercise training (RET)-induced skeletal muscle hypertrophy. How-ever, it is unclear how increasing bouts of RET affects ribosome content and biogenesis. This was investigated in the present study using simulated RET where rat skeletal muscle is subjected to increasing bouts of electrical stimulation. Sprague-Dawley rats were randomly assigned to the following seven groups: sedentary for 5 days (SED) or 6 wk (SED_6w), resistance-exercise trained with 1 bout (1B), 2 bouts (2B). 3 bouts (3B), 6 bouts (6B), and 18 bouts (18B). RET was simulated on the right gastrocnemius muscle by transcutaneous electric stimulation under isoflurane anesthesia, and a RET bout was given 3 times a week. Rats in 1B, 2B, and 3B groups showed increased 45S precursor (pre-) rRNA and 18S +28S rRNA content per muscle weight and elevated mRNA levels of c-myc and upstream binding factor (UBF). Increases in phosphorylated UBF and total cyclin D1 protein level were observed 48 h after RET; the former increased as a function of RET duration. In 3B, 6B, and 18B groups, the 18S +28S rRNA content per muscle weight was kept unchanged, and 45S pre-rRNA, cyclin D1, and phosphorylated UBF levels in 18B were lower than those in 3B. These results suggest that RET activates ribosome biogenesis and increases ribosome content through modulation of UBF and cyclin D1 activity at its early phase. Additional bouts of RET may not lead to a further increase in ribosome content per muscle weight through possibly the attenuation of transcription process.NEW & NOTEWORTHY Ribosome biogenesis has been implicated in resistance exercise training-induced skeletal muscle hypertrophy. However, it remains unclear how this is influenced by the volume of repeated bouts of resistance exercise training. Using resistance exercise training model with rat skeletal muscle, we provide evidence that ribosome biogenesis is stimulated by the initial few bouts of resistance exercise training with no additional effect of further increase in the exercise bout.