Pulsed electromagnetic fields alleviate streptozotocin‑induced diabetic muscle atrophy.

Diabetic muscle atrophy causes a reduction of skeletal muscle size and strength, which affects normal daily activities. However, pulsed electromagnetic fields (PEMFs) can retard the atrophy of type II fibers (ActRIIB) in denervated muscles. Therefore, the purpose of the present study was to determine whether PEMFs can alleviate streptozotocin (STZ)‑induced diabetic muscle atrophy. To do this, 40 Sprague‑Dawley (SD) rats were randomly divided into four groups (n=10 per group): The normal control group (NC; nondiabetic rats without treatment); the diabetic mellitus group (DM; STZ‑induced rats without treatment); the diabetic insulin‑treated group (DT; diabetic rats on insulin treatment, 6‑8 U/d twice a day for 6 weeks) as a positive control; and the diabetic PEMFs therapy group (DP; diabetic rats with PEMFs exposure treatment, 15 Hz, 1.46 mT, 30 min/day for 6 weeks). Body weight, muscle strength, muscle mass and serum insulin level were significantly increased in the DP group compared with the DM group. PEMFs also decreased the blood glucose level and altered the activity of metabolic enzymes. PEMFs significantly increased the cross‑sectional area of muscle fiber. In addition, PEMFs significantly activated protein kinase B (Akt) and mammalian target of rapamycin (mTOR), and inhibited the activity of myostatin (MSTN), ActRIIB and forkhead box protein O1 (FoxO1) compared with the DM group. Thus indicating that the Akt/mTOR and Akt/FoxO1 signaling pathways may be involved in the promotion of STZ‑induced diabetic muscle atrophy by PEMFs. The results of the present study suggested that PEMFs stimulation may alleviate diabetic muscle atrophy in the STZ model, and that this is associated with alterations in multiple signaling pathways in which MSTN may be an integral factor. MSTN‑associated signaling pathways may provide therapeutic targets to attenuate severe diabetic muscle wasting.