Topographically speciﬁc regeneration of sensory axons in the spinal cord

PNAS, 2010 · DOI: 10.1073/pnas.1003287107 · Published: June 22, 2010

Spinal Cord Injury Regenerative Medicine Neurology

Simple Explanation

This study investigates how sensory axons regenerate in the spinal cord after injury, focusing on the precision with which they reconnect to their original target areas. Two treatments, a soluble Nogo receptor peptide (sNgR) and artemin (ART), were tested for their ability to promote axon regeneration and the accuracy of these regenerated connections. The key finding is that artemin treatment leads to more precise, topographically specific regeneration of sensory axons compared to sNgR, suggesting that artemin allows axons to utilize existing guidance cues in the spinal cord.

Study Duration

4 weeks

Participants

Male Sprague–Dawley rats (200–250 g)

Evidence Level

Not specified

Key Findings

1
Artemin (ART) treatment promotes topographically specific regeneration of sensory axons after dorsal root crush, while soluble Nogo receptor peptide (sNgR) does not.
2
Myelinated muscle and cutaneous sensory afferents regenerated to the correct spinal segments and appropriate regions within the spinal gray matter with artemin treatment.
3
Regenerated unmyelinated axons expressing calcitonin gene-related peptide project only to superficial laminae of the dorsal horn, similar to uninjured nociceptive afferents, with artemin treatment.

Research Summary

The study examines the topographic specificity of sensory axon regeneration in the spinal cord following dorsal root crush, using soluble Nogo receptor peptide (sNgR) and artemin (ART) treatments. sNgR promotes robust regeneration of myelinated axons, but the regenerated axons project aberrantly throughout the dorsal white and gray matter. Artemin treatment leads to the re-establishment of projections of different classes of sensory axons to their appropriate topographic locations within the spinal cord.

Practical Implications

Targeted Therapies

Artemin could be a therapeutic target for promoting specific sensory input restoration after brachial plexus injury.

Guidance Cues

The existence of molecular cues in the adult mammalian spinal cord can direct regenerating sensory axons to their targets.

Growth Program Stimulation

Effective treatments should be developed to stimulate growth programs in neuronal cell bodies.

Study Limitations

1
The study focuses primarily on sensory axon regeneration after dorsal root crush and may not be directly applicable to other types of spinal cord injuries.
2
The mechanism by which systemic artemin promotes topographic specificity remains unclear and requires further investigation.
3
The study uses a rat model, and the results may not be directly translatable to humans.

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