Beneficial impacts of neuromuscular electrical stimulation on muscle structure and function in the zebrafish model of Duchenne muscular dystrophy

Abstract

Neuromuscular electrical stimulation (NMES) allows activation of muscle fibers in the absence of voluntary force generation. NMES could have the potential to promote muscle homeostasis in the context of muscle disease, but the impacts of NMES on diseased muscle are not well understood. We used the zebrafish Duchenne muscular dystrophy (dmd) mutant and a longitudinal design to elucidate the consequences of NMES on muscle health. We designed four neuromuscular stimulation paradigms loosely based on weightlifting regimens. Each paradigm differentially affected neuromuscular structure, function, and survival. Only endurance neuromuscular stimulation (eNMES) improved all outcome measures. We found that eNMES improves muscle and neuromuscular junction morphology, swimming, and survival. Heme oxygenase and integrin alpha7 are required for eNMES-mediated improvement. Our data indicate that neuromuscular stimulation can be beneficial, suggesting that the right type of activity may benefit patients with muscle disease.

Modeling neuromuscular diseases in zebrafish

“…Muscle structure analyzed via phalloidin staining showed fewer degeneration of fibers in dmd mutants following eNMES and pNMES. Additionally, all NMES paradigms except pNMEs showed an increased number or length of NMJs in dmd mutant fish ( Kilroy et al, 2022 ). Furthermore, the assessment of motor behavior revealed an increase in swimming distance and velocity in dmd mutants following eNMES compared to control dmd mutants, providing evidence of improved muscular function following an improved muscular structure ( Kilroy et al, 2022 ).…”

“…Additionally, all NMES paradigms except pNMEs showed an increased number or length of NMJs in dmd mutant fish ( Kilroy et al, 2022 ). Furthermore, the assessment of motor behavior revealed an increase in swimming distance and velocity in dmd mutants following eNMES compared to control dmd mutants, providing evidence of improved muscular function following an improved muscular structure ( Kilroy et al, 2022 ). Sarcomere length impacts muscle function ( Moo and Herzog, 2018 ), therefore, the length of sarcomere was also assessed in 8 dpf dmd mutants following eNMES and found to be significantly increased compared to control fish.…”

“…Guillaume Benjamin Amand Duchenne, a French neurologist who described DMD in 1861, proposed the idea of electric stimulation as a potential therapy for dystrophin-deficient muscles ( Duchenne et al, 1871 ; Barnard et al, 1986 ). Elisabeth et al performed a longitudinal study on sapje zebrafish DMD mutant with four paradigms of neuromuscular electric stimulation (NMES), ranging from low frequency and high voltage to high frequency and low voltage ( Kilroy et al, 2022 ). The four NMES paradigms were named as Power NMES (pNMES), Strength NMES (sNMES), Hypertrophy NMES (hNMES) and Endurance NMES (eNMES) with pNMES being the low frequency and high voltage stimulation and eNMES being high frequency and low voltage stimulation.…”

“…Analysis of RNA sequencing data revealed upregulation of HO in dmd mutant zebrafish larvae following eNMES training. Injection of hmox1a morpholino at 1 dpf in dmd mutants following eNMES protocol showed no improvement in muscle organization and fiber detachment ( Kilroy et al, 2022 ). This suggests that HO is necessary for eNMES-mediated recovery.…”

Commentary: Zebrafish as a Model for Osteoporosis—An Approach to Accelerating Progress in Drug and Exercise-Based Treatment

“…Exercise-induced changes to bone can also be studied using a controlled swimming program such as the one developed by Suniaga et al Zebrafish were placed to swim against laminar currents in swimming chambers, and zebrafish displayed bone adaptation in response to musculoskeletal exercise [ 54 ]. While exercise interventions for OP have yet to be studied in zebrafish [ 54 ], research conducted in a zebrafish model for Duchenne muscular dystrophy indicates that certain forms of exercise may be beneficial to patients with this condition [ 61 ]. Thus, the study of exercise-based interventions for OP in zebrafish models for OP is a promising area for future research [ 54 ].…”