家兔面神经撞击伤后胶质细胞源性的神经营养因子mRNA在面神经元中的表达特点

目的:了解胶质细胞源性的神经营养因子(GDNF)mRNA在面神经撞击伤这一特定致伤条件下的表达特点, 结合其他学者的实验结果,探讨GDNF在面神经损伤后再生中可能发挥的生物学作用。方法:以撞击枪在10 m/s 撞击速度,715 J撞击能量下建立家兔面神经撞击伤模型,撞击后3、7、14、21 d采用原位杂交方法分别检测面神经元及周围面神经中GDNF mRNA的表达范围及表达特点,并对面神经元表达数量进行计数分析。结果:面神经受到撞击后在不同时间点的面神经元中均可检出强烈的GDNF mRNA表达,第7天达高峰,随后逐渐下降,至第21天仍可见较高水平表达。周围神经雪旺氏细胞及正常面神经元均不表达GDNF mRNA。结论:GDNF是一种应激性表达的运动神经元营养因子,其表达特点与面神经撞击伤后的再生过程在时间上具有一致性,表明它可能在面神经损伤后的再生过程中发挥作用。

The Character of Glial Line-cell Derived Neurotrophic Factor mRNA Expression in a Facial Nerve-striking Model

OBJECTIVE: It has been known that glial line-cell derived neurotrophic factor (GDNF) has the nutritional and protective effect in motor neurons. In this experiment, we investigated the character of GDNF mRNA expression in a facial nerve-striking model; combined with other scholars' experimental results; and analyzed what role GDNF plays in the regeneration process of injured motor nerves. METHODS: We established a striking model in rabbit facial nerves with a striking gun with the striking velocity of 10 m/s and the total striking energy of 7.5 J. Then we detected the GDNF mRNA expression in facial neurons and axons with in situ hybridization on days 3, 7, 14 and 21 after striking. We counted the expression numbers of facial neurons and, compared with normal facial neurons and peripheral facial nerves. RESULTS: We detected GDNF mRNA expression in the facial neurons from day 3 to day 21 after the facial nerve injured by striking. The peak of GDNF mRNA expression appeared on the 7th day, and then the expression number of facial neurons decreased gradually. A high level expression was also detected on day 21. GDNF mRNA expression was not detected neither in Schwann cells nor in normal facial neurons from the 3rd day to the 21st day. CONCLUSION: GDNF is a kind of neurotrophic growing factor (NGF) that could be activated by injury. The character of GDNF mRNA expression was accordant to the process of nerve regeneration. These results showed that GDNF plays a very important role in the regeneration of injured motor nerves.