Department of Physical Education and Sport Sciences, University of Kurdistan, Sanandaj, Iran.
Liver and Digestive Research Center, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran.
J Physiol Biochem. 2021 May;77(2):331-339. doi: 10.1007/s13105-021-00801-4. Epub 2021 Feb 26.
The unfolded protein response (UPR) plays a pivotal role in some exercise training-induced physiological adaptation. Our aim was to evaluate the changes in the protein kinase R-like endoplasmic reticulum kinase (PERK) arm of the UPR and hypertrophy signaling pathway following 8 weeks of resistance training and creatine (Cr) supplementation in rats. Thirty-two adult male Wistar rats (8 weeks old) were randomly divided into 4 groups of 8: untrained + placebo (UN+P), resistance training + placebo (RT+P), untrained + Cr (UN+Cr), and resistance training + Cr (RT+Cr). Trained animals were submitted to the ladder-climbing exercise training 5 days per week for a total of 8 weeks. Cr supplementation groups received creatine diluted with 1.5 ml of 5% dextrose orally. The flexor hallucis longus (FHL) muscle was extracted 48 h after the last training session and used for western blotting. After training period, the RT+Cr and RT+P groups presented a significant increase in phosphorylated and phosphorylated/total ratio hypertrophy indices, phosphorylated and phosphorylated/total ratio PERK pathway proteins, and other downstream proteins of the PERK cascade compared with their untrained counterparts (P < 0.05). The increase in hypertrophy indices were higher but PERK pathway proteins were lower in the RT-Cr group than in the RT+P group (P < 0.05). There was no significant difference between the untrained groups (P > 0.05). Our study suggests that resistance training in addition to Cr supplementation modifies PERK pathway response and improves skeletal muscle hypertrophy.
未折叠蛋白反应（UPR）在某些运动训练引起的生理适应中起着关键作用。我们的目的是评估大鼠 8 周抗阻训练和肌酸（Cr）补充后 UPR 和肥大信号通路中蛋白激酶 R 样内质网激酶（PERK）臂的变化。32 只成年雄性 Wistar 大鼠（8 周龄）随机分为 4 组，每组 8 只：未训练+安慰剂（UN+P）、抗阻训练+安慰剂（RT+P）、未训练+Cr（UN+Cr）和抗阻训练+Cr（RT+Cr）。训练动物每周进行 5 天的爬梯运动训练，共 8 周。Cr 补充组口服 1.5ml5%葡萄糖稀释的肌酸。最后一次训练结束后 48 小时提取屈肌趾长肌（FHL），用于 Western 印迹分析。经过训练期后，与未训练组相比，RT+Cr 和 RT+P 组的磷酸化和磷酸化/总比值肥大指数、磷酸化和磷酸化/总比值 PERK 通路蛋白以及 PERK 级联的其他下游蛋白均显著增加（P<0.05）。与 RT+P 组相比，RT-Cr 组的肥大指数增加更高，但 PERK 通路蛋白降低（P<0.05）。未训练组之间无显著差异（P>0.05）。我们的研究表明，抗阻训练加 Cr 补充可改变 PERK 通路反应，改善骨骼肌肥大。
