Exercise Decreases Myelin-Associated Glycoprotein Expression in the Spinal Cord and Positively Modulates Neuronal Growth

Glia, 2007 · DOI: 10.1002/glia.20521 · Published: July 1, 2007

Spinal Cord Injury Neurology Rehabilitation

Simple Explanation

Neurons often struggle to grow due to inhibitory factors like myelin. This study explores whether exercise can help neurons overcome these obstacles. The research indicates that exercise reduces myelin's inhibitory effect on neuronal growth. Neurons grown on myelin from exercised rats showed more growth compared to those grown on myelin from sedentary rats. The study found that exercise decreases the levels of myelin-associated glycoprotein (MAG), a known inhibitor of axonal growth, suggesting this is how exercise promotes growth.

Study Duration

3, 7, or 28 days

Participants

Adult male Sprague-Dawley rats

Evidence Level

Not specified

Key Findings

1
Exercise reduces the levels of myelin-associated glycoprotein (MAG) in the spinal cord, a potent axonal growth inhibitor.
2
Blocking brain-derived neurotrophic factor (BDNF) during exercise suppressed the exercise-related MAG decrease, indicating BDNF's role in this process.
3
Exercise increased protein kinase A (PKA) levels, and this effect was reversed by blocking BDNF, further supporting BDNF's involvement.

Research Summary

This study investigates the potential of exercise to overcome the inhibitory effects of myelin on neuronal growth in the central nervous system. The findings demonstrate that exercise reduces the inhibitory capacity of myelin, promoting a more permissive environment for axonal growth. Exercise significantly decreased the levels of myelin-associated glycoprotein (MAG), a potent axonal growth inhibitor, in the spinal cord. This decrease was mediated by brain-derived neurotrophic factor (BDNF) and protein kinase A (PKA). In vitro studies showed that cortical neurons grown on myelin from exercised rats exhibited more pronounced neurite extension and increased cyclin-dependent kinase 5 (cdk5) activity, suggesting that exercise alters myelin properties to favor neuronal growth.

Practical Implications

Therapeutic Potential

Exercise may be a valuable therapeutic strategy for promoting neural repair and regeneration after CNS injury.

Molecular Mechanisms

Understanding the molecular mechanisms by which exercise modulates myelin and promotes neuronal growth can lead to the development of targeted therapies.

Rehabilitation Strategies

Incorporating exercise into rehabilitation programs may enhance the regenerative capacity of neurons and improve functional outcomes after spinal cord injury.

Study Limitations

1
The study was conducted on rats, and the results may not be directly applicable to humans.
2
The specific types and intensity of exercise were controlled in the study, which may not reflect real-world exercise conditions.
3
Further research is needed to fully elucidate the molecular mechanisms underlying the effects of exercise on myelin and neuronal growth.

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