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Facial Nerve Surgery in the Rat Model to Study Axonal Inhibition and Regeneration
Published on: May 5, 2020
Experimental nerve transfer model in the neonatal rat.
Matthias E Sporer1, Martin Aman2, Konstantin D Bergmeister3
1Christian Doppler Laboratory for the Restoration of Extremity Function; Clinical Laboratory for Bionic Extremity Reconstruction, Department of Surgery, Medical University of Vienna, Vienna, Austria; Division of Biomedical Research, Medical University of Vienna, Vienna, Austria.
This study developed a neonatal rat model for peripheral nerve repair, showing nerve transfers can reinnervate muscles but reduce motoneurons. Neonatal nerve injury and repair differ significantly from adult models.
Area of Science:
- Neuroscience
- Regenerative Medicine
- Pediatric Surgery
Background:
- Peripheral nerve injuries in neonates, particularly brachial plexus birth injuries, often require surgical reconstruction.
- Current surgical strategies are primarily based on adult animal models, which may not accurately reflect the immature neuromuscular system's response.
- A lack of reliable experimental models hinders the investigation of nerve regeneration and repair in neonates.
Purpose of the Study:
- To establish and validate a neonatal rat forelimb model for studying peripheral and central nervous system responses to nerve lesions and surgical repair.
- To investigate the efficacy of nerve transfer in reconstructing a peripheral nerve injury in neonates.
- To compare the outcomes of neonatal nerve repair with findings in adult models.
Main Methods:
- A neonatal rat model was developed within 24 hours after birth.
- Three groups were established: nerve transfer (ulnar nerve to musculocutaneous nerve), negative control (nerve division without repair), and positive control (sham surgery).
- Functional recovery was assessed using the Bertelli test (grooming behavior), and at 12 weeks, muscle force, weight, cross-sectional area, and motoneuron pool size (via retrograde labeling) were analyzed.
Main Results:
- Nerve transfer successfully reinnervated target muscles, indicated by restored muscle force, weight, and cross-sectional area in mature animals.
- No spontaneous regeneration was observed in the negative control group.
- Retrograde labeling revealed a reduction in the ulnar nerve motoneuron pool following nerve transfer, leading to fewer motoneurons innervating the biceps compared to the native musculocutaneous nerve.
Conclusions:
- The neonatal neuromuscular system exhibits distinct responses to nerve injury and repair compared to adults, explaining observed reductions in muscle force.
- Neonatal nerve regeneration utilizes inherent regenerative capacities and compensatory mechanisms for functional recovery.
- The validated neonatal rat model is suitable for detailed investigations into pathophysiological changes, neural reorganization, and nerve transfer efficacy in immature subjects.
