1. Circadian rhythms modulate the effect of eccentric exercise on rat soleus muscles.
- Author
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Chang, Shuo-wen, Yoshihara, Toshinori, Tsuzuki, Takamasa, Natsume, Toshiharu, Kakigi, Ryo, Machida, Shuichi, and Naito, Hisashi
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SOLEUS muscle ,CIRCADIAN rhythms ,LABORATORY rats ,RATS ,MUSCULAR hypertrophy - Abstract
We investigated whether time-of-day dependent changes in the rat soleus (SOL) muscle size, after eccentric exercises, operate via the mechanistic target of rapamycin (mTOR) signaling pathway. For our first experiment, we assigned 9-week-old male Wistar rats randomly into four groups: light phase (zeitgeber time; ZT6) non-trained control, dark phase (ZT18) non-trained control, light phase-trained, and dark phase-trained. Trained animals performed 90 min of downhill running once every 3 d for 8 weeks. The second experiment involved dividing 9-week-old male Wistar rats to control and exercise groups. The latter were subjected to 15 min of downhill running at ZT6 and ZT18. The absolute (+12.8%) and relative (+9.4%) SOL muscle weights were higher in the light phase-trained group. p70S6K phosphorylation ratio was 42.6% higher in the SOL muscle of rats that had exercised only in light (non-trained ZT6). Collectively, the degree of muscle hypertrophy in SOL is time-of-day dependent, perhaps via the mTOR/p70S6K signaling. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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