Effects of aerobic exercise training on muscle plasticity in a mouse model of cervical spinal cord injury

Abstract

Cervical spinal cord injury (SCI) results in permanent life-altering motor and respiratory deficits. Other than mechanical ventilation for respiratory insufficiency secondary to cervical SCI, effective treatments are lacking and the development of animal models to explore new therapeutic strategies are needed. The aim of this work was to demonstrate the feasibility of using a mouse model of partial cervical spinal hemisection at the second cervical metameric segment (C2) to investigate the impact of 6 weeks training on forced exercise wheel system on locomotor/respiratory plasticity muscles. To measure run capacity locomotor and respiratory functions, incremental exercise tests and diaphragmatic electromyography were done. In addition, muscle fiber type composition and capillary distribution were assessed at 51 days following chronic C2 injury in diaphragm, extensor digitorum communis (EDC), tibialis anterior (TA) and soleus (SOL) muscles. Six-week exercise training increased the running capacity of trained SCI mice. Fiber type composition in EDC, TA and SOL muscles was not modified by our protocol of exercise. The vascularization was increased in all muscle limbs in SCI trained group. No increase in diaphragmatic electromyography amplitude of the diaphragm muscle on the side of SCI was observed, while the contraction duration was significantly decreased in sedentary group compared to trained group. Cross-sectional area of type IIa myofiber in the contralateral diaphragm side of SCI was smaller in trained group. Fiber type distribution between contralateral and ipsilateral diaphragm in SCI sedentary group was affected, while no difference was observed in trained group. In addition, the vascularization of the diaphragm side contralateral to SCI was increased in trained group. All these results suggest an increase in fatigue resistance and a contribution to the running capacity in SCI trained group. Our exercise protocol could be a promising non-invasive strategy to sustain locomotor and respiratory muscle plasticity following SCI.

Exercise‐induced histone H3 trimethylation at lysine 27 facilitates the adaptation of skeletal muscle to exercise in mice

“…Exercise training is reported to improve the oxidative capacity of skeletal muscles in rodents (Egan & Zierath, 2013). However, there was no pronounced phenotypic shift of muscle fibres in response to chronic exercise training in previous studies (Ishihara et al, 1998;Jesus et al, 2021;Kriketos et al, 1995;Rodnick et al, 1992). The results of the present study (Figs 5 and 7) showed no effects of exercise training on the fibre phenotype in the DMSO-treated group, which is consistent with previous observations.…”

When Spinal Neuromodulation Meets Sensorimotor Rehabilitation: Lessons Learned From Animal Models to Regain Manual Dexterity After a Spinal Cord Injury

“…Thus, tasks training fine digit control (e.g., SPRG) may result more appropriate for the recovery from mild or moderate injuries, or those affecting distal rather than proximal movements. On the other hand, treadmill locomotion ( 48 ) and forced/voluntary running wheel ( 49 ), which involve strength/cardiovascular resistance, can also promote recovery of forelimb movements. However, these trainings may entail a confounding factor when interpreting motor improvement as it is difficult to dissect the neural bases from the exercise-induced benefits ( 31 ).…”

Effects of Chronic High-Frequency rTMS Protocol on Respiratory Neuroplasticity Following C2 Spinal Cord Hemisection in Rats

“…Despite some promise with TMS, the results from the present study may reflect the fact that 10 Hz rTMS alone may be insufficient to stimulate significant functional diaphragmatic recovery. Combining the rTMS protocol employed in the present study with other therapeutic interventions (e.g., activity-based therapy [40,67]) may be more efficacious.…”