Rho-inhibition by local application of c3-toxin for enhancement of axonal sprouting in a rat end-to-side nerve repair model.

Introduction: The aim of the presented study was to investigate nerve regeneration after application of C3-Toxin, a Rho-GTPase inhibitor and to correlate morphometry, neurophysiology, and function in an end-to-side peroneal/tibial nerve repair model of the rat. Materials and methods: Twenty rats with a peroneal to tibial end-to-side neurorrhaphy were divided into two groups: 1) control group, 2) C3 fusion toxin group with intrafascicular application of 1 μg/100 μl C3 fusion toxin. Survival time was 8 weeks. Nerve conduction velocities and motor function were analyzed and histomorphological evaluation consisting of measurement of intraneural collagen level, axon count, total nerve area, myelination index, and N-ratio followed. Results: Evaluation of motor function and nerve conduction did not show any statistical differences. Histological analysis revealed higher axon count, thicker myelin sheaths, and higher myelination index in the C3 fusion toxin group (P < 0.001). Comparison of N-ratio and intraneural collagen level were without statistical significance. Conclusion: The current study shows that application of C3 fusion toxin leads to higher myelination and increases axonal sprouting. © 2012 Wiley Periodicals, Inc. Microsurgery, 2012.