The effect of melatonin and platelet gel on sciatic nerve repair: an electrophysiological and stereological study

Nerve regeneration after surgical reconstruction is far from optimal, and thus effective strategies for improving the outcome of nerve repair are being sought. In this experiment, we verified if postoperative intraperitoneal melatonin (MLT) administration after intraoperative platelet gel application improves peripheral nerve regeneration. In adult male rats, 1-cm long sciatic nerve defects were repaired using four different strategies: autologous nerve graft repair followed by MLT (NM, n = 5), collagen conduit repair followed by MLT (CM, n = 5), platelet gel-enriched collagen conduit repair followed by MLT (CGM, n = 6), and platelet gel-enriched collagen conduit (CG, n = 5) repair followed by no substance administration. Sham operated animals were used as controls (Cont, n = 5). Ninety days after surgery, the nerve regeneration outcome was comparatively assessed by means of electrophysiological and stereological analysis. Electrophysiology revealed no significant differences between the experimental and the sham control groups. Stereological analysis showed no significant differences among the experimental groups regarding axon size and myelin thickness, but the axon number was significantly lower in the CM compared to Cont and NM group. Moreover, there was no significant difference between number of axons in CG and Cont groups, between CGM and CM, and between CM and NM. Although it was observed that platelet gel have a positive effect on nerve regeneration, but a combination of local platelet gel with MLT does not have the same effect on nerve repair.