[Role of ciliary neurotrophic factor in regeneration of severed facial nerve of cats].

Objective: To study the role of extrinsic (CNTF) in the regeneration of severed facial nerve in cats.

Method: The facial nerve in temporal bone of adult cats were severed and the severed ends were connected with CNTF or saline applied at the connection. Electrophysiological examination and immunocytochemistry were performed with immunoelectron microscope for morphological analysis at 2, 4 and 8 weeks after the operation.

Results: Two weeks after operation, both CNTF and saline groups failed to exhibit muscular excitement by facial nerve stimulation, but the amount of myelinated nerve fibers had statistical difference between the two groups (P<0.05). At 4 weeks, the latency of the facial muscle excitement was 7.832+/-2.695 ms in CNTF group and 16.120+/-3.516 ms in saline group, and the average number of myelinated axons was significantly different between the two groups (1,435+/-318 vs 957+/-269, P<0.05). At the 8th weeks, the latency of facial muscle excitement was reduced to 3.125+/-0.165 ms in CNTF group and to a comparable level of 3.095+/-0.178 ms in saline group (P>0.05), and the average number of myelinated axons increased to 1,695+/-283 and 1,543+/-320 respectively in the two groups (P>0.05). Significant increase of Schwann cells was noted in both groups at this stage.

Conclusion: Local application of CNTF may enhance facial early-stage nerve regeneration in adult cats, but its long-term effects remain unclear.