Full Anatomical Recovery of the Dopaminergic System after a Complete Spinal Cord Injury in Lampreys

Neural Plasticity, 2015 · DOI: http://dx.doi.org/10.1155/2015/350750 · Published: March 2, 2015

Spinal Cord Injury Regenerative Medicine Neurology

Simple Explanation

Following a spinal injury, lampreys initially experience paralysis but regain locomotion after weeks, accompanied by axon regeneration and new neuron production. This study analyzes changes in the dopaminergic system after spinal transection, focusing on dopaminergic cell numbers and innervation in the spinal cord, along with D2 receptor expression. The research reveals the full anatomical regeneration of the dopaminergic system after an initial decrease in dopaminergic cells and fibers. The study found that the numbers of dopaminergic cells recovered both rostrally and caudally to the site of the injury. Interestingly, the expression of the D2 receptor remained unchanged even when dopaminergic innervation was reduced. The study concludes that spinal cord injury in lampreys leads to a full anatomical recovery of their dopaminergic system.

Study Duration

24 weeks

Participants

33 lampreys with spinal cord transection, 12 control lampreys

Evidence Level

Not specified

Key Findings

1
Numbers of dopaminergic cells were recovered rostrally and caudally to the site of injury, indicating a regeneration of the cell population after the initial injury.
2
Quantification of dopaminergic profiles revealed the full recovery of the dopaminergic innervation of the spinal cord both rostral and caudal to the injury site.
3
No significant changes were observed in the expression of the D2 receptor at time points when reduced dopaminergic innervation was evident, suggesting that D2 receptor expression is not acutely affected by the injury or initial loss of dopaminergic fibers.

Research Summary

This study investigates the anatomical changes in the dopaminergic system of lampreys following complete spinal cord injury and during the recovery period, focusing on dopaminergic innervation, cell numbers, and D2 receptor expression. The findings indicate that lampreys exhibit a full anatomical recovery of the dopaminergic spinal system, contrasting with the incomplete recovery observed in the glutamatergic system, suggesting differential responses among neurotransmitter systems. The study also reports the spontaneous and complete recovery of the dopaminergic innervation of the spinal cord distal to the site of injury, highlighting a difference from other vertebrates like adult zebrafish.

Practical Implications

Therapeutic Potential

Understanding the mechanisms behind the spontaneous regeneration of the dopaminergic system in lampreys could provide insights for developing therapies to promote regeneration in humans with spinal cord injuries.

Comparative Neurobiology

Comparing the regenerative capabilities of lampreys with non-regenerating vertebrates helps identify key factors that facilitate or inhibit spinal cord repair.

Drug Development

Identifying molecules involved in the intrinsic regeneration of dopaminergic cells and fibers in lampreys can serve as a basis for designing drugs to aid spinal cord recovery.

Study Limitations

1
The study is limited to anatomical observations and does not fully explore the functional implications of the dopaminergic system recovery.
2
The mechanisms underlying the regeneration of dopaminergic cells and fibers are not fully elucidated.
3
The study focuses solely on lampreys, and further research is needed to determine the applicability of these findings to other vertebrates.

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