Live Imaging of Dorsal Root Axons after Rhizotomy

J. Vis. Exp., 2011 · DOI: 10.3791/3126 · Published: September 1, 2011

Spinal Cord Injury Neurology Medical Imaging

Simple Explanation

The study focuses on observing the behavior of damaged nerve fibers (dorsal root axons) in real-time within living mice after a specific type of spinal injury (rhizotomy). The researchers use advanced imaging techniques and genetically modified mice with fluorescently labeled neurons to track the regeneration process of these axons. The goal is to gain a better understanding of why these damaged nerve fibers fail to properly regenerate into the spinal cord, which contributes to chronic pain and sensory loss.

Study Duration

5-20 days

Participants

thy1-YFP mice

Evidence Level

Not specified

Key Findings

1
After a crush injury, most YFP+ axons grew through the injury site within three days.
2
Regenerating neurites elongated through degenerating axon fragments and arrived at the DREZ as early as 4 days after the crush.
3
The regenerating axons, upon reaching the DREZ, exhibited chronic immobilization, remaining immobile without further growth or retraction over a period of two weeks.

Research Summary

This study describes methods for live imaging of dorsal root axons after rhizotomy, focusing on techniques to assure successful long-term and repeated imaging of regenerating DR axons. Strategies include methods that eliminate repeated intubation and respiratory interruption, minimize surgery-associated stress and scar formation, and acquire stable images at high resolution without phototoxicity. The study observes that regenerating axons quickly reach the DREZ after crush injury but then become chronically immobilized, suggesting a potential reason for the failure of DR axons to regenerate within the spinal cord.

Practical Implications

Improved Imaging Techniques

The described strategies can be used to improve in vivo imaging of nerve regeneration, reducing mortality and improving image quality.

Understanding Regeneration Failure

The finding of chronic immobilization at the DREZ provides insights into why DR axons fail to regenerate, suggesting potential therapeutic targets.

Refined Surgical Procedures

Minimizing surgery-associated stress and scar formation can enhance the success of longitudinal in vivo studies.

Study Limitations

1
Mortality rate of approximately 25% due to surgical and anesthetic procedures.
2
Widefield microscopy provides insufficient spatial resolution for detailed analysis.
3
Potential for confounding effects due to artifacts from surgical procedures and photoxicity.

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