Improved Electrical Stimulation-Based Exercise Model to Induce Mice Tibialis Anterior Muscle Hypertrophy and Function

Abstract

Efficient and suitable animal models directed to skeletal muscle hypertrophy are highly needed; nevertheless, the currently available models have limitations, such as restricted hypertrophy outcome and prolonged protocols; thus, additional research is required. In this study, we developed an improved muscle training protocol for mice by directly stimulating the tibialis anterior (TA) muscle motor point using electrical stimulation. C57BL/6 adult male mice were separated into four groups: CTR (control groups for one and two weeks), ES1 (electrical stimulation for one week), and ES2 (electrical stimulation for two weeks). Following muscle training, TA was taken for further examination. The results demonstrated a steady increase in the fiber cross-sectional area as a result of muscle training (ES1, 14.6% and ES2, 28.9%, p p = 0.0205) and 30%, respectively (p = 0.0260). To assess the tissue remodeling response in this model, we evaluated satellite cell activity and observed an increase in the number of Pax-7-positive nuclei after one and two weeks of muscle training (both >2-fold, p p = 0.0057) without fiber damage. Accordingly, phosphorylation of mTOR and p70 increased following two weeks of muscle training (17%, p = 0.0215 and 66%, p = 0.0364, respectively). The results indicate that this muscle training strategy is appropriate for promoting quick and intense hypertrophy.

Keywords

• skeletal muscle hypertrophy
• neuromuscular electrical stimulation
• resistance exercise
• tibialis anterior
• mice