胶质细胞源性神经营养因子在自体静脉桥修复面神经缺损中促进神经再生的效应

Effect of glial cell derived neurotrophic factor on regeneration of facial nerve defects by autogenous vein conduit

目的旨在研究胶质细胞源性神经营养因子(GDNF)在自体静脉桥修复面神经缺损中促进神经再生的效应。方法选用36只成年雄性新西兰大白兔作为实验动物,切除双侧10 mm长面神经颊支,制作面神经缺损动物模型。以同侧面后静脉作为神经再生管道,修复面神经缺损。静脉管腔内分别注入生理盐水(A组,n=16)或GDNF溶液(B组,n=16)。分别于手术后当时,及术后4、8、16周诱发面神经动作电位,评价神经功能。于术后4、8、16周每组分别随机处死6只动物,切取术区神经标本,行组织学与透射电镜观察。结果手术后当时,2组实验动物均无动作电位产生;而术后4、8、16周,2组均有动作电位出现。除术后4周时动作电位波宽2组无显著差异外,B组动作电位的波幅在术后4周和8周均显著高于A组(P<0.01),而潜伏期显著短于A组(P<0.01),波宽在术后8周显著高于A组(P<0.01)。术后16周,除动作电位波幅B组显著高于A组外(P<0.01),波宽和潜伏期2组均无显著差异。形态学及透射电镜观察显示,B组再生神经有更多的成熟的有髓神经纤维,更早出现有活力的Schwann细胞。结论 GDNF在自体静脉桥修复面神经缺损中可有效促进神经再生;GDNF复合自体静脉桥为临床面神经缺损修复提供了一个极具价值的途径。

Objective To study the effects of glial cell derived neurotrophic factor（GDNF） on regeneration of facial nerve defects by autogenous facial vein conduit.Methods Thirty-six rabbits were used in this study and 10 mm-length facial nerve defects were made on both sides of all animals.The nerve gaps were bridged using autoge-nous posterior facial vein graft of the same side.The animals received injection of either saline（group A,n=16） or GDNF（group B,n=16） into the veins.Nerve function was evaluated by evoking nerve action potential immediately after operation and 4,8 and 16 weeks after operation.Regenerated nerve samples were harvested at 4,8,and 16 weeks after operation and processed for histology and transmitting electron microscopic examination（TEM）.Results Action potential did not exist immediately after operation but it was evoked at 4,8,and 16 weeks in both groups.At 4 and 8 weeks after operation,the amplitude and width of action potential were significantly higher in group B than group A（P0.01）,except wave width at 4 weeks,which showed no significant differences,while the latency period was significantly shorter in group B than that in group A（P0.01）.At 16 weeks,action potential was similar between two groups,except wave amptitude,which was higher in group B than group A（P0.01）.Morphologic and TEM examinations showed more matured myelinated nerve fibers and active Schwann＇s cells in group B when compared group A during the whole regeneration pro-cess.Conclusion GDNF can promote nerve regeneration at early stage during reconstruction of facial nerve defects by autogenous faical vein conduit and combination of GDNF and autogenous vein graft provides a valuable method for clinical reconstruction of facial nerve defects.