Spinal Cord Injury Induces Changes in Electrophysiological Properties and Ion Channel Expression of Reticulospinal Neurons in Larval Lamprey

The Journal of Neuroscience, 2008 · DOI: 10.1523/JNEUROSCI.3840-07.2008 · Published: January 16, 2008

Spinal Cord Injury Regenerative Medicine Neurology

Simple Explanation

This study investigates how spinal cord injuries affect nerve cells (reticulospinal neurons) in larval lampreys, focusing on changes in their electrical properties and the expression of specific ion channels after injury (axotomy). The researchers found that after a spinal cord injury, these nerve cells initially show altered firing patterns and reduced activity of calcium channels. However, with time, they recover their normal function and ion channel expression. The research suggests that these changes in calcium channel activity may be important for the nerve cells to regrow their axons after the injury, a process known as axonal regeneration.

Study Duration

2-3 weeks (short recovery), 12-16 weeks (long recovery)

Participants

70 larval sea lamprey

Evidence Level

Not specified

Key Findings

1
Axotomized RS neurons initially display altered firing patterns, including single short bursts or short repetitive bursts, in response to sustained depolarization.
2
At short recovery times, axotomized RS neurons show a significant reduction in mRNA levels of lamprey HVA calcium and SKKCa channels.
3
Blocking calcium channels in uninjured RS neurons results in altered firing patterns that resemble those produced by axotomy, suggesting a link between calcium channel activity and neuronal firing patterns after injury.

Research Summary

The study examines the electrophysiological and molecular changes in reticulospinal (RS) neurons of larval lampreys following spinal cord injury, specifically focusing on the effects of axotomy on firing patterns, afterpotentials, and ion channel expression. Key findings include initial alterations in firing patterns and reduction in HVA calcium and SKKCa channel expression in axotomized RS neurons, followed by recovery of these properties at longer recovery times. The research suggests that downregulation of calcium channels in axotomized RS neurons may play a role in maintaining intracellular calcium levels conducive to axonal regeneration.

Practical Implications

Understanding Regeneration

Provides insights into the mechanisms underlying axonal regeneration in lower vertebrates, which may have implications for developing regenerative therapies for spinal cord injuries in humans.

Calcium Channel Role

Highlights the importance of calcium channel regulation in neuronal responses to injury and axonal regeneration, suggesting potential therapeutic targets.

Firing Pattern Recovery

Demonstrates the potential for injured neurons to recover their normal electrophysiological properties over time, offering hope for functional recovery after spinal cord injury.

Study Limitations

1
The study is conducted on larval lampreys, which may not fully represent the complexity of mammalian spinal cord injury and regeneration.
2
The mechanisms underlying the recovery of ion channel expression and electrophysiological properties at long recovery times are not fully elucidated.
3
The precise relationship between changes in action potential components (fAHP, ADP, sAHP) and altered firing patterns in axotomized RS neurons requires further investigation.

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