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Electrical stimulation modulates Wnt signaling and regulates genes for the motor endplate and calcium binding in muscle of rats with spinal cord transection

BMC Neuroscience, 2013 · DOI: 10.1186/1471-2202-14-81 · Published: August 2, 2013

Spinal Cord InjuryPhysiologyNeurology

Simple Explanation

Spinal cord injuries (SCI) lead to muscle atrophy and a shift in muscle fiber types. Electrical stimulation (ES) can help restore muscle mass and fiber distribution. This study investigates the molecular changes in rat soleus muscle after initiating isometric resistance exercise via ES. The study compares the effects of ES on mRNA levels with those induced by gastrocnemius tenotomy (GA), a procedure that overloads the soleus muscle. The research aims to understand how paralyzed muscle adapts to exercise compared to normally innervated muscle. Researchers found that ES increased expression of certain signaling molecules (Hey1, Pitx2) and altered the expression of genes related to calcium binding proteins and acetylcholine receptors. These changes suggest that Notch and Wnt signaling pathways may play a role in ES-induced muscle mass increases.

Study Duration
7 days
Participants
Female Wistar rats with spinal cord transection
Evidence Level
Not specified

Key Findings

  • 1
    ES increased expression of Hey1 and Pitx2, suggesting increased Notch and Wnt signaling, respectively, indicating involvement of these pathways in ES-induced muscle mass increases.
  • 2
    Microarray analysis revealed that ES increased genes coding for calcium binding proteins and nicotinic acetylcholine receptors, and altered the expression of genes involved in blood vessel formation and morphogenesis.
  • 3
    Compared to GA, ES induced different gene expression changes, with only a small overlap of altered genes, suggesting that molecular adaptations of paralyzed soleus to resistance exercise are delayed or defective compared to normally innervated muscle.

Research Summary

This study investigates the early molecular adaptations in rat soleus muscle after initiating isometric resistance exercise by electrical stimulation (ES) following spinal cord injury (SCI). ES increased expression of Hey1 and Pitx2, suggesting increased Notch and Wnt signaling, respectively. Microarray analysis showed increased expression of genes coding for calcium binding proteins and nicotinic acetylcholine receptors. Molecular adaptations of paralyzed soleus to resistance exercise are delayed or defective compared to normally innervated muscle.

Practical Implications

Therapeutic targets

Notch and Wnt signaling pathways may be potential therapeutic targets for promoting muscle hypertrophy in paralyzed muscle.

Rehabilitation strategies

Understanding the molecular adaptations to ES can inform the design of more effective rehabilitation strategies for individuals with SCI.

Comparative exercise models

Differences between ES and GA highlight the importance of considering the specific exercise model and the underlying properties of muscle when studying adaptations to resistance exercise.

Study Limitations

  • 1
    The study was conducted in female rats, and results may not be generalizable to males.
  • 2
    The duration of ES was limited to 7 days, and longer-term effects may differ.
  • 3
    The study focused on the soleus muscle, and other muscles may exhibit different responses to ES.

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