甲状腺激素在新西兰家兔面神经损伤修复中的作用

目的 观察甲状腺激素在兔面神经损伤修复中的作用.方法 25只成年健康新西兰家兔,设立正常对照组、手术对照组、T3治疗组3个实验组.制作双侧面神经横断损伤、损伤局部硅胶管套接的动物模型;其中右侧为T3治疗组,硅胶管中注入甲状腺素溶液16～18μl;左侧为手术对照组,硅胶管中注入等量生理盐水.在术后4、6周取再生面神经,电镜检测有髓轴突比率和髓鞘厚度,取脑桥中下部组织,运用免疫组织化学SP法检测面神经核运动神经元中神经营养因子NGF、BDNF表达的变化,光镜下计数两种神经营养因子标记的阳性细胞数.结果 电镜结果显示在术后4周和6周,T3治疗组的有髓轴突比率和髓鞘厚度均＞手术对照组,差异有统计学意义(P＜0.01).术后4周,手术对照组和T3治疗组NGF、BDNF两种分子标记的阳性细胞数较之正常对照组增幅明显,差异有统计学意义(P＜0.01).术后6周,T3治疗后阳性细胞数NGF、BDNF比手术对照组NGF、BDNF仍有明显增加,差异有统计学意义(P＜0.01).结论 面神经横断损伤后,再生室中注射T3能够促进面神经有髓轴突比率和髓鞘厚度的增加,并且增加面神经核运动神经元中神经营养因子NGF、BDNF的表达.

Study on role of thyroid hormone in repair of rabbit facial nerve injury

Objective To investigate the effection of thyroid hormone in the regeneration of facial nerve.Methods Twenty-five New Zealand adult rabbits (age range:6-8 months )were selected. These rabbits were divided into three groups(normal,operated and T3-treated groups). Five rabbits in normal control group were taken facial nerve and inferior-middle part of pons (containing facial nucleus) without any treatment. Select 20 New Zealand adult rabbits randomly, the effect of a single and local treatment with triiodothyronine(T3) on axonal growth across a gap between sectioned ends of facial nerve within silicone chambers was examined. After nerve transaction and surgical implantation, silicone chambers were filled with either a neutral PH solution of triiodothyronine dissolved in NaOH or with sterile solvent as control 4 and 6 weeks affer surgery,regenerated facial never was studied by morphological analysis.Results Resules of electron microscopy demonstrated that four weeks and six weeks after surgery,T3 treatment group ingelinated axon ratio and the thickness of the myelin sheath were greater than the control gropu,statistical analysis was significant (P<0.01).The immuohistochemistry resules of Facial motoneurons showed that:after four weeks,in treatment group,NGF-positive cells and BDNF-positive cells compared with normal control group significantly inerease,statistical analysis was significant difference (P<0.01).After six weeks,the two positive cells seill increased significantly,statistical analysis was significant difference(P<0.01).Conclusion A single and local administration of thyroid hormone at the level of the transected facial nerve is sufficient to rapidly set off several mechanisms which, in turn, produce a stimulating and lasting effect on peripheral nerve regeneration. It can increase the myelinated axons rate,moreover, thyroid hormone can increase the expression of NGF in the facial motoneurons.