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Biochemical, morphological, and functional changes during peripheral nerve regeneration
S Ribaric1, A Stefanovska, M Brzin
1Institute of Pathophysiology, Ljubljana, Yugoslavia.
Molecular and Chemical Neuropathology
|October 1, 1991
Summary
Successful axon regeneration and muscle function recovery after nerve injury depend on nerve-muscle connection reestablishment. Despite subnormal enzyme activity, regenerated nerve terminals can restore normal muscle force.
Area of Science:
- Neuroscience
- Regenerative Medicine
- Muscle Physiology
Background:
- Axon regeneration is crucial for restoring target organ function after nerve injury.
- Muscle contraction recovery involves complex processes including axon regrowth and neuromuscular junction reinnervation.
Purpose of the Study:
- To correlate the time-course and interdependence of axon regeneration, neuromuscular junction reestablishment, and muscle force recovery following sciatic nerve crush injury in rats.
Main Methods:
- Sciatic nerve crush in rats.
- Monitoring choline acetyltransferase (ChAT) activity for axon ingrowth.
- Electron microscopic cytochemistry of acetylcholine esterase (AChE) for neuromuscular junction reinnervation.
- Measuring in vivo isometric muscle contraction force.
Main Results:
- Regenerating axons entered calf muscles by 14 days post-injury, indicated by increased ChAT activity.
- Neuromuscular junctions began reinnervation by 12 days, with steady increases in reinnervated plates and junction surface area.
- Muscle force recovery was significant by 35 days, coinciding with morphological normalization of neuromuscular junctions, though ChAT activity remained subnormal.
Conclusions:
- Muscle force recovery can be achieved despite incomplete normalization of ChAT activity, suggesting sufficient acetylcholine (ACh) release from regenerated nerve terminals.
- Functional recovery of muscle contraction is a more accurate measure of successful axon regeneration than enzyme activity alone.