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Denervated single myofibers: neurite interactions and synaptic molecules
1Department of Anatomy and Cell Biology, University of Michigan Medical School, Ann Arbor.
Muscle & Nerve
|December 1, 1989
Summary
Long-term denervation reduces neuromuscular junction molecules like gelasmin, hindering neurite reinnervation of muscle fibers. This loss of gelasmin may explain why nerves fail to reconnect with muscles after prolonged disuse.
Area of Science:
- Neuroscience
- Muscle Biology
- Regenerative Medicine
Background:
- Understanding molecular cues for neuromuscular junction (NMJ) reinnervation is crucial for treating muscle denervation.
- Aging and denervation differentially affect muscle fiber properties and their capacity for reinnervation.
Purpose of the Study:
- To investigate the molecular changes in denervated adult rat muscle fibers.
- To compare neurite interactions with muscle fibers subjected to varying denervation periods and aging.
Main Methods:
- Cultured adult rat muscle fibers denervated in vivo for 2-24 months.
- Co-culture of denervated muscle fibers with embryonic ventral spinal cord explants.
- Analysis of neurite contacts and expression of neuromuscular junction molecules (acetylcholinesterase, acetylcholine receptors, gelasmin).
Main Results:
- Acetylcholinesterase (AChE), acetylcholine receptors (AChRs), and gelasmin decreased with denervation duration, but not with aging.
- Neurite contacts on cultured muscle fibers were significantly reduced with longer denervation periods (17-24 months).
- Gelasmin, unlike AChE and AChRs, was present at neurite contact sites, suggesting its role in reinnervation.
Conclusions:
- Loss of gelasmin from long-term denervated muscle fibers may impede neurite contact formation and maintenance.
- Gelasmin is a potential molecular cue for neuromuscular reinnervation.
- These findings offer insights into the molecular basis of failed reinnervation in chronically denervated muscles.