Functional recovery of axoplasmic transport of regenerative peripheral nerve promoted by FK506

Abstract

Objective To explore the effect of FK506 (tacrolimus) on functional recovery of axoplasmic transport of the regenerative peripheral nerve.Methods Forty-eight Sprague-Dawley rats with 10 mm gap of sciatic nerve were randomly divided into 2 even groups.The nerve defects were bridged with our self-designed double-channel nerve conduits of fusiform shape.In group A,100 μL of chitin for medical use was injected into each of the 2 channels of the conduit; in group B,after 100 μL of chitin was injected into each of the 2 channels,one channel of the conduit was injected with 10 μL of FK506 (subgroup B1 ) and the other with 10 μL of isotonic saline (subgroup B2).At 12 and 16 weeks after operation,we evaluated axoplasmic transport of the regenerative nerve in the 2 channels with horseradish peroxidase(HRP) and nuclear yellow(NY) observations.At 16 weeks regenerative nerve conduction velocity(NCV) was measured and ultrastructure of the regenerative nerve was also observed with transmission electron microscopy(TEM).Results At 12 and 16 weeks after operation,TEM showed no significant difference in the regenerative nerve fibers between the 2 channels in group A.In group B,more well-arranged and even regenerative fibers were observed in subgroup B1 than in subgroup B2.The HRP and NY tracing showed much more positive neurons densely distributing in the spine cord in subgroup B1 than in subgroup B2.The NCV was 35.62 m/s +3.23 m/s in subgroup B1,significantly faster than that (22.62 m/s ±+ 2.12 m/s) in subgroup B2( P ＜ O.05).Conclusion Functional recovery of axoplasmic transport of the regenerative nerve fibers can be significantly promoted by FK506. Key words: Peripheral nerves; Axoplasmic transport; Horseradish peroxidase