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Effects of different exercise modes on neuromuscular junction and metabolism of skeletal muscle-related proteins in aging rats

SU Yan-Hong^1,*, CHENG Yi², LI Ting-Ting¹, ZHANG Yi-Chen¹, DU Ze-Yu³, CHEN Juan¹, WANG Fu-Qing¹, LIU Zhong-Hao⁴, GONG Wen-Han⁵

¹School of Physical Education, Liaoning Normal University, Dalian 116029, China；²Qilu Medical University, Zibo 255300, China；³School of Life Science, Liaoning Normal University, Dalian 116029, China；⁴Dalian Bay Middle School, Dalian 116033, China；⁵School of Physical Education, Minnan University of Science and Technology, Quanzhou 362799, China

Abstract

The present study aimed to explore the effects of different exercise modes on neuromuscular junction (NMJ) and metabolism of skeletal muscle-related proteins in aging rats. Ten from 38 male Sprague-Dawley (SD) rats (3-month-old) were randomly selected into young (Y) group, while the rest were raised to 21 months old and randomly divided into elderly control (O), endurance exercise (EN) and resistance exercise (R) groups. After 8 weeks of corresponding exercises training, the gastrocnemius muscles of rats were collected, and the expression of S100B in Schwann cells was detected by immunofluorescence staining. Western blot was used to detect the protein expression levels of agglutinate protein (Agrin), low-density lipoprotein receptor-related protein 4 (Lrp4), muscle- specific kinase protein (MuSK), downstream tyrosine kinase 7 (Dok7), phosphorylated protein kinase B (p-Akt), phosphorylated mammalian target rapamycin (p-mTOR), and phosphorylated forkhead box O1 (p-FoxO1) in rat gastrocnemius muscles. The results showed that, endurance and resistance exercises increased the wet weight ratio of gastrocnemius muscle in the aging rats. The protein expression of S100B in the R group was significantly higher than those in the O and EN groups. Proteins related to NMJ function, including Agrin, Lrp4, MuSK, and Dok7 were significantly decreased in the O group compared with those in the Y group. Resistance exercise up-regulated these four proteins in the aging rats, whereas endurance exercise could not reverse the protein expression levels of Lrp4, MuSK and Dok7. Regarding skeletal muscle-related proteins, the O group showed down-regulated p-Akt, and p-mTOR protein expression levels and up-regulated p-FoxO1 protein expression level, compared to the Y group. Resistance and endurance exercises reversed the changes in p-mTOR and p-FoxO1 protein expression in the aging rats. These findings demonstrate that both exercise modes can enhance NMJ function, increase protein synthesis and reduce the catabolism of skeletal muscle-related proteins in aging rats, with resistance exercise showing a more pronounced effect.

Key words: Skeletal muscle; atrophy of muscles; neuromuscular junction; exercise

Received: 　　Accepted:

Corresponding author: 苏艳红　　E-mail:

DOI: 10.13294/j.aps.2024.0039

Citing This Article：

SU Yan-Hong, CHENG Yi, LI Ting-Ting, ZHANG Yi-Chen, DU Ze-Yu, CHEN Juan, WANG Fu-Qing, LIU Zhong-Hao, GONG Wen-Han. Effects of different exercise modes on neuromuscular junction and metabolism of skeletal muscle-related proteins in aging rats. Acta Physiol Sin 2024; 76 (3): 376-384 (in Chinese with English abstract).