The relationship between changes in the expression of growth associated protein–43 and functional recovery of the injured inferior alveolar nerve following transection without repair in adult rats

• Published in: Journal of cranio-maxillo-facial surgery Vol. 43; no. 9; pp. 1906 - 1913
• Main Authors: Ceber, Mehmet, Sener, Umit, Mihmanli, Ahmet, Kilic, Ulkan, Topcu, Birol, Karakas, Merve
• Format: Journal Article
• Language: English
• Published: Scotland Elsevier Ltd 01.11.2015
• Subjects: Action Potentials - physiology; Animals; Compound muscle action potentials; Dentistry; GAP-43; GAP-43 Protein - metabolism; Immunohistochemistry; Inferior alveolar nerve; Male; Mandibular Nerve - metabolism; Nerve regeneration; Nerve Regeneration - physiology; Rats, Sprague-Dawley; Recovery of Function - physiology; Surgery; Transection; Trigeminal Ganglion - metabolism; Trigeminal Nerve Injuries - metabolism; Trigeminal Nerve Injuries - physiopathology; Compound muscle action potentials; Inferior alveolar nerve; Nerve regeneration; GAP-43; Transection
• ISSN: 1010-5182; 1878-4119
• DOI: 10.1016/j.jcms.2015.08.018

Abstract Objective The objective of this study was to analyze the changes in the expression of growth associated protein–43 (GAP-43) in trigeminal ganglions (TGs) and in the distal stumps of transected inferior alveolar nerves (IANs), and to clarify the relationship between these changes and functional recovery of the transected IAN without repair using a rat IAN axotomy model. Material and methods Following transection, GAP-43 expression was measured at multiple time points. The functional recovery of the transected IAN was evaluated based on the compound muscle action potentials recorded from the digastric muscle. Results GAP-43 expression in TGs was significantly higher at 2, 7, 14, 28, and 56 days following IAN transection compared to that in samples from sham-operated rats (p < 0.0005, p < 0.0005, p < 0.0005, p = 0.007, and p = 0.023, respectively). GAP-43 expression in the distal stumps of transected IANs was significantly higher at 2, 7, 14, and 28 days following IAN transection compared to that in samples taken from sham rats (p < 0.0005, p < 0.0005, p < 0.0005, and p = 0.009, respectively). GAP-43 expression in the distal stumps of transected IANs returned nearly to sham levels by day 56 following IAN transection. On days 7, 14, 28, and 56 following transection, the amplitude of the compound muscle action potential gradually increased, the latency gradually decreased, and the duration gradually increased. The amplitude, latency, and duration of the compound muscle action potentials nearly returned to sham levels on post-transection day 56. Conclusions Time-dependent changes in the expression of GAP-43 in both TGs and distal stumps of transected IANs without repair are synchronously consistent with the regeneration and functional recovery of the transected IAN. The recovery of the amplitude, latency, and duration of the compound muscle action potentials indicates increased myelination and increased axon density of the regenerated nerve fibers.