Pathological changes of distal motor neurons after complete spinal cord injury

Molecular Brain, 2019 · DOI: https://doi.org/10.1186/s13041-018-0422-3 · Published: January 4, 2019

Simple Explanation

This study investigates the changes in the spinal cord below the injury site after a complete spinal cord injury in mice. Researchers looked at the structure and biology of nerve cells (motor neurons) in the lumbar spinal cord, which controls leg movement. The study found that even though the connections to these motor neurons are reduced after the injury, the cells themselves still have the potential to form new connections. This suggests that therapies targeting this area could help improve recovery after spinal cord injury. Researchers used a technique called laser microdissection to isolate specific nerve cells and study their gene activity. This allowed them to see how the injury affected the function of these cells and their ability to communicate with other neurons.

Study Duration

3 months

Participants

30 adult female C57/BL6 mice

Evidence Level

Not specified

Key Findings

1
The size of the spinal cord decreases not only at the injury site but also in areas both above and below the injury.
2
The number of connections (synaptic boutons) and activity levels are reduced in motor neurons in the lumbar spinal cord, indicating a decrease in stimulation from the brain.
3
Lumbar motor neurons maintain their ability to form new connections and their cholinergic activity, even in a 'semi-dormant' state after the injury.

Research Summary

This study examined the pathological changes in the distal spinal cord after complete thoracic SCI in mice, focusing on motor neurons in the lumbar region. Key findings include widespread atrophy in the spinal cord, decreased presynaptic inputs to lumbar motor neurons, and reduced neuronal activity in these neurons. Despite these changes, lumbar motor neurons maintained the expression of postsynaptic molecules and cholinergic activity, suggesting a potential for functional recovery with targeted therapeutic interventions.

Practical Implications

Therapeutic Target

The area caudal to the lesion could be a potential target to improve functional outcome after SCI.

Rehabilitation Strategies

Rehabilitation programs may promote synaptic reorganization of lumbar motor neurons that rewires the connection with proximal circuits.

Stem Cell Transplantation

Reconsider the ideal location to transplant neural stem cells into the injured spinal cord; the lesion epicenter may not necessarily be the ideal place.

Study Limitations

1
The study was conducted on mice, and the results may not directly translate to humans.
2
The study focused on a specific time point (3 months after injury), and the long-term effects of SCI on motor neurons were not examined.
3
The precise mechanisms underlying the maintenance of postsynaptic molecules and cholinergic activity in lumbar motor neurons remain unclear.

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