Effect of nerve growth factor and ciliary neurotrophic factor on peripheral nerve regeneration: comparative study

Objective To compare the different effect of nerve growth factor (NGF)or ciliary neurotrophic factor(CNTF) on promoting nerve regeneration in sciatic nerve in rats. Methods The newly double channel nerve conduit of fusiform shape is symmetry to the middle axis and its vertical length is 10mm, with outside diameter 2mm and inside diameter 1.8mm. Thirty two rats with 10mm gap of sciatic nerve were randomly divided into two groups, with 16 in each. In group A, 200μl of chitin for medical use was injected into the conduit. In group B, the two branches of the conduit was injected with 100μl of the chitin and 5μl of NGF(20 ng/μl) at the left side, 100μl of the chitin and CNTF (60 ng/μl) at the right side. On postoperative 12 and 16 weeks, the nerve regeneration was evaluated by electrophysiological and morphological assessment.Results There was no statistically significant difference in the nerve regeneration in two braches in group A on postoperative 16 weeks. In group B at the NGF side, there was fair-arranged nerve fiber, mainly with myelinated nerve, and with thick myelin large axon diameter. In group B at the CNTF side, well arranged and distributed nerve fiber was observed. The number of myelinated and unmyelinated nerve was increased. The motor nerve conduction velocity in the NGF branch was slower than that in the CNTF side. The latency of compound motor action potential and cortical somatosensory evoked potential in the NGF side was longer than that in the CNTF side, but the amplitude in the NGF side was lower than that in the CNTF side.Conclusion NGF can promote the regeneration and myelinogeny of myelinated fiber. CNTF can promote the regeneration of both myelinated and unmyelinated fiber, and its functional recovery is superior to that of NGF.