Unexpected Survival of Neurons of Origin of the Pyramidal Tract after Spinal Cord Injury

The Journal of Neuroscience, 2010 · DOI: 10.1523/JNEUROSCI.1433-10.2010 · Published: August 25, 2010

Spinal Cord Injury Regenerative Medicine Neurology

Simple Explanation

The study investigates whether spinal cord injury (SCI) causes the death of brain cells that control movement, specifically those that give rise to the corticospinal tract (CST). Researchers assessed damage to the CST axons in the medullary pyramid after SCI. The researchers examined the medullary pyramid of Sprague Dawley rats after acute and chronic SCI at different levels (C5 and T9). They looked for signs of axon degeneration and counted the number of myelinated axons. The findings suggest that SCI does not lead to the death of CST cell bodies in the cortex. Therefore, treatments to promote axon regeneration in the spinal cord may not need to focus on preventing the death of these brain cells.

Study Duration

Up to 1 year

Participants

Sprague Dawley rats

Evidence Level

Level III, Experimental Study

Key Findings

1
Only a small fraction of axons in the medullary pyramid showed signs of degeneration after SCI, comparable to uninjured rats.
2
Axon counts in the medullary pyramid did not decrease after SCI, regardless of injury level, severity, or time after injury.
3
Rats with chronic SCI had fewer myelinated axons in the medullary pyramid at 1 year after injury than age-matched controls, suggesting that injury may affect ongoing myelination of axons during aging.

Research Summary

This study challenges the long-standing controversy about whether spinal cord injury (SCI) causes retrograde cell death of corticospinal tract (CST) neurons. By directly assessing CST axons in the medullary pyramid of rats after SCI, the research provides evidence against significant neuronal death. The findings indicate that SCI does not lead to substantial degeneration or loss of CST axons in the medullary pyramid, even after severe injuries or prolonged periods. This suggests that the cell bodies of these neurons in the cortex survive SCI. The implications of this research are significant for regenerative therapies, suggesting that interventions aimed at promoting axon regeneration in the spinal cord do not necessarily need to include strategies to prevent the death of CST neurons in the cortex.

Practical Implications

Therapeutic Strategies

Therapeutic strategies aimed at promoting axon regeneration of the CST in the spinal cord do not require a separate intervention to prevent retrograde degeneration of upper motoneurons in the cortex.

Focus on Regeneration

Research efforts and resources can be directed towards other, more fruitful directions, focusing on axonal regeneration rather than preventing neuronal death.

Understanding Myelination

Further studies are needed to elucidate the mechanisms underlying the reduction in myelination after spinal cord injuries.

Study Limitations

1
The study was conducted on Sprague Dawley rats, and results may not be generalizable to other species or strains.
2
The assessment of axonal degeneration relied on specific morphological criteria, and other forms of degeneration might not have been detected.
3
The long-term effects of SCI on CST neurons beyond one year were not investigated.

Your Feedback

Was this summary helpful?

Back to Spinal Cord Injury