Contralateral Axon Sprouting but Not Ipsilateral Regeneration Is Responsible for Spontaneous Locomotor Recovery Post Spinal Cord Hemisection

Frontiers in Cellular Neuroscience, 2021 · DOI: 10.3389/fncel.2021.730348 · Published: August 26, 2021

Spinal Cord Injury Regenerative Medicine Neurology

Simple Explanation

This study investigates how movement recovers after spinal cord injury. Researchers looked at rats with spinal cord damage on one side. They found that the recovery was due to nerve fibers from the undamaged side sprouting and compensating. The sprouting fibers help to take over the function of the damaged fibers. The study suggests that encouraging this sprouting could be a way to help people recover from spinal cord injuries. It highlights the importance of the uninjured side of the spinal cord.

Study Duration

5 weeks

Participants

59 female Sprague-Dawley rats

Evidence Level

Not specified

Key Findings

1
Spontaneous hindlimb locomotor recovery occurs in rats four weeks after spinal cord hemisection.
2
Contralateral axonal remodeling, not ipsilateral regeneration, is responsible for this spontaneous recovery.
3
Corticospinal tract (CST) fibers sprout from the contralateral side at the lumbar spinal cord in hemisection model rats.

Research Summary

This study investigates the mechanisms behind spontaneous locomotor recovery after spinal cord hemisection in rats. The researchers found that significant hindlimb locomotor recovery occurs four weeks after the injury. The key finding is that contralateral CST sprouting, rather than ipsilateral regeneration or new neuronal circuits at the lesion site, is primarily responsible for this recovery. This was verified through lesion experiments and CST tracing. These results highlight the importance of contralesional plasticity in functional recovery after incomplete SCI and suggest potential therapeutic targets.

Practical Implications

Therapeutic Target Identification

The finding that contralateral CST sprouting is crucial for recovery suggests that therapies aimed at promoting or enhancing this sprouting could improve outcomes after spinal cord injury.

Rehabilitation Strategies

Rehabilitation strategies could be designed to specifically encourage the use of the less affected side of the body to stimulate contralateral sprouting and functional compensation.

Understanding Spontaneous Recovery

A better understanding of the molecular signals that regulate contralateral sprouting could lead to the development of drugs that promote this process and improve spontaneous recovery.

Study Limitations

1
The study focuses solely on CST sprouting, while other descending motor tracts might also contribute to recovery.
2
The molecular regulation of the observed axonal reorganization is not fully understood.
3
The study is conducted in a rat model, and the results may not be directly translatable to humans.

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