2036 Exercise Improves Motor Regeneration and Alters Inflammatory Cytokines in Nerve and Muscle Following Peripheral Nerve Injury

INTRODUCTION: Traumatic peripheral nerve injury (PNI) has a substantial impact on patient function and quality of life. While surgical repair techniques have improved, complete functional recovery remains challenging. There is a need for adjunct therapies to improve the regenerative process. Exercise is known to augment nerve healing, likely through modification of the inflammatory processes that accompany peripheral injury. METHODS: 8-week-old male C57BL/6J mice underwent right sciatic nerve crush injury (n=10 per group). The exercise group was given free access to running wheels for 4 weeks, while the sedentary group was housed in standard cages. Hindpaw grip strength was tested weekly. At 4 weeks, sciatic nerve, gastrocnemius, and tibialis anterior tissue were harvested. Immunohistochemistry was performed to identify reinnervation of the neuromuscular junctions (NMJ). Cytokine analysis was performed on sciatic nerve and muscle using a dot blot assay (n=3). RESULTS: There was no difference in grip strength between the groups at baseline. Grip strength in both groups declined significantly following injury (13% average). At 3 and 4 weeks, grip strength was significantly stronger in the exercise group compared to the sedentary group (p=0.02). There was a significant increase of reinnervation of NMJ's in the exercise group at 4 weeks (p<0.001). Cytokine analysis from both tissues of the exercise group showed an increased expression of specific targets that may influence regeneration following injury. CONCLUSIONS: Following PNI, exercise resulted in increased reinnervation within the muscle and improved grip strength. Neuroinflammatory pathways in the muscle and nerve have been identified for further analysis to determine their role in nerve regeneration.