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Dissection of the Transversus Abdominis Muscle for Whole-mount Neuromuscular Junction Analysis
Published on: January 11, 2014
Differential skeletal muscle gene expression after upper or lower motor neuron transection
Richard J Zeman1, Jingbo Zhao, Yuangfei Zhang
1Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York, NY 10595, USA. Zeman@nymc.edu
Pflugers Archiv : European Journal of Physiology
|February 14, 2009
Summary
Spinal cord injury (SCI) causes greater muscle atrophy than denervation, with distinct gene expression patterns. SCI-induced atrophy peaks early, while denervation shows gradual increases, influenced by motor neuron type and muscle activity.
Area of Science:
- Neuroscience
- Muscle Physiology
- Molecular Biology
Background:
- Disuse atrophy stems from upper motor neuron loss (spinal cord injury, SCI) or lower motor neuron loss (denervation).
- SCI leads to delayed spasticity, while denervation causes rapid muscle fibrillations.
- Understanding differential atrophy mechanisms is crucial for therapeutic interventions.
Purpose of the Study:
- To compare muscle atrophy rates and gene expression following SCI versus denervation.
- To investigate the temporal dynamics of atrophy-related genes (MAFbx, MuRF1, IGF-1) in response to different motor neuron injuries.
- To correlate gene expression changes with muscle atrophy patterns and spontaneous muscle activity.
Main Methods:
- Male rats underwent either spinal cord or sciatic nerve transection.
- Muscle tissue was collected at 3, 7, and 14 days post-injury for analysis.
- Quantitative assessment of muscle atrophy and gene expression levels (MAFbx, MuRF1, IGF-1, IGF-1R, GADD45, myogenin, Runx1) was performed.
Main Results:
- Muscle atrophy peaked at 1 week post-SCI and then declined, whereas denervation atrophy increased gradually and plateaued.
- Higher levels of ubiquitin ligase genes (MAFbx, MuRF1) were observed with SCI-induced atrophy compared to denervation.
- Insulin-like growth factor 1 (IGF-1) expression peaked earlier after denervation, coinciding with fibrillations.
Conclusions:
- Distinct temporal patterns of muscle atrophy and gene expression occur following SCI versus denervation.
- Differences in MAFbx, MuRF1, and IGF-1 expression correlate with the type of motor neuron injury.
- Spontaneous muscle contractile activity likely contributes to the observed time-dependent variations in atrophy and gene regulation.
