Acute and Prolonged Hindlimb Exercise Elicits Different Gene Expression in Motoneurons than Sensory Neurons after Spinal Cord Injury

Brain Res, 2012 · DOI: 10.1016/j.brainres.2011.12.015 · Published: February 15, 2012

Spinal Cord Injury Neuroplasticity Rehabilitation

Simple Explanation

This study examines how genes are expressed in different nerve cells after a spinal cord injury, especially when combined with exercise. The focus is on genes that help nerves grow and adapt. The researchers looked at specific nerve cells that control movement (motoneurons) and those that sense body position (sensory neurons). They wanted to see how these cells respond to injury and exercise differently. Rats with spinal cord injuries were given either one week or four weeks of cycling exercise for their hindlimbs, and then the activity of certain genes was measured in their spinal cords.

Study Duration

4 weeks

Participants

30 adult female Sprague-Dawley rats

Evidence Level

Not specified

Key Findings

1
Exercise increased the expression of genes related to nerve growth and plasticity, specifically BDNF and GDNF, in motoneurons and intermediate gray matter.
2
Sensory neurons in the DRG showed little change in neurotrophic factor gene expression with either injury or exercise, but caspase mRNA expression was increased by injury and decreased by exercise.
3
In whole spinal cord samples, injury increased the expression of mRNA for TrkB, caspases, and HSPs, while exercise increased HSP expression and decreased caspase-7 expression.

Research Summary

The study investigated gene expression changes in motor and sensory neurons following spinal cord injury (SCI) and exercise, focusing on neurotrophic factors, heat shock proteins (HSPs), and caspases. Exercise, particularly passive cycling, significantly impacted the expression of neurotrophic factors in motor system cells, with motoneurons and intermediate gray matter showing increased production of BDNF and GDNF. Sensory neurons exhibited minimal changes with SCI alone but showed decreased caspase expression with exercise, suggesting cell-specific responses to injury and activity-dependent plasticity.

Practical Implications

Therapeutic Potential

Understanding cell-specific gene expression changes can inform the development of targeted therapies to enhance recovery after SCI.

Exercise Optimization

Identifying the mechanisms by which exercise alters physiological and behavioral function can lead to optimized exercise regimens for SCI patients.

Proprioceptive Stimulation

The study suggests that proprioceptive stimulation is crucial for the observed gene expression changes, highlighting the importance of therapies that incorporate such stimulation.

Study Limitations

1
The study measures relative changes in gene expression, which can be sensitive to technical and sample size issues.
2
The exact mechanisms responsible for the changes in gene expression are difficult to determine due to the nature of the assays performed.
3
The study acknowledges the possibility of contamination by other cell types in laser micro-dissected samples, although efforts were made to minimize this.

Your Feedback

Was this summary helpful?

Back to Spinal Cord Injury