Low-frequency Electrical Stimulation Alleviates Immobilization-evoked Disuse Muscle Atrophy via Repressing Autophagy in Skeletal Muscle of Rabbits

Abstract Objective : The present study was to investigate the effect of low-frequency electrical stimulation on disuse muscle atrophy and its mechanism in a rabbit model of extending knee joint contracture. Methods : This study designed two experiments. In the time-point experiment, 24 rabbits were randomly divided into Control 1(Ctrl1), immobilization for 2 weeks (I-2), I-4, and I-6 groups. In the intervention experiment, 24 rabbits were also randomly divided into Control 2 (Ctrl2), electrical stimulation (ES), natural recovery (NR) and electrical stimulation treatment (EST) groups. All intervention effects were assessed by evaluating the knee joint range of motion (ROM), cross-sectional area (CSA) of muscle and the expression of autophagy-related proteins. Results: Time-point experiment showed that immobilization reduced knee ROM, muscle CSA, and activated autophagy in skeletal muscle. Levels of four autophagic proteins including p-mTOR, Atg7, p62 and LC3B-II, were significantly elevated in the skeletal muscle of I-4 group. The intervention experiment further presented that LFES significantly improved the immobilization-induced ROM and CSA reduction. Additionally, LFES significantly reversed autophagy activation of skeletal muscle caused by immobilization. Conclusions : Low-frequency electrical stimulation alleviates immobilization-evoked disuse muscle atrophy maybe via inhibiting autophagy in skeletal muscle of rabbits.