神经营养素4在面神经的转运研究

目的 探讨面神经再生微环境及神经营养素4（NT－4）对神经细胞的作用。方法 将新西兰兔一侧面神经干横断后置入硅胶再生室，再将^132I-NT-4(10μl／只，约7．4MBq）注入其再生室。另取1只家兔分别在注药后不同时刻行头部冠状位平面显像，其余取面神经干、脑干和对侧面神经干，利用放射性核素示踪技术测定NT－4在面神经的转运情况。另取1只置入再生室的兔，同时在再生室注入1mg脑源性神经营养因子（BDNF）和7．4MBq^131I-NT-4后，不同时刻行头部冠状位平面显像。结果 注药后4小时就有5．08％的^131I-NT-4转运到面神经干中，8、12小时达高峰，分别为20．58％和22．74％；8小时有34．75％转运至脑干，12小时转运至脑干的量达45．57％，且^131I-NT-4在面神经的转运受BDNF的明显抑制。结论 NT－4在面神经中存在受体介导逆行转运。

A study of on the transport of neurotrophin-4 in facial nerve]

OBJECTIVE: This is a study on the transport information of neurotrophin-4 (NT-4) in facial nerve using radioactive tracer technique. METHODS: After one lateral facial nerve trunk of adult rabbit was transected, a silicone chamber was inserted between the stumps, and 7.4 MBq of 131I-NT-4 was administered into the chamber. At the distinct moment of post-injection, the head of one rabbit was imaged at coronary position, the bilateral facial nerve trunk and brain-stem of the others were collected and counted respectively. After 1 mg of brain-derived neurotrophic factor (BDNF) and 7.4 MBq of 131I-NT-4 were administered into the chamber of one rabbit, the rabbit was imaged at coronary position of head at distinct moment. RESULTS: 5.08% of 131I-NT-4 was transported into facial nerve trunk at 4 h of post-injection. 131I-NT-4 presented high peak in facial nerve trunk during the period of 8, 12 h, the peak values were 20.58% and 22.74% respectively. 34.75% and 45.57% of 131I-NT-4 were transported into the brain-stem of experimental side at 8 h and 12 h respectively. The transport of 131I-NT-4 was markedly restrained by BDNF in facial nerve. CONCLUSION: NT-4 displays a receptor-mediated retrograde transport in facial nerve.