5 Hz和20 Hz磁场对中脑神经干细胞分化的影响

目的：观察5Hz和20Hz磁场（EMF）对新生大鼠中脑神经干细胞神经元向分化的影响。方法：神经干细胞分别置于5Hz和20Hz正弦交变磁场（8mT）中诱导变化，每天上午、下午各1次，每次15min，分别作用于1d、5d或10d，同时设立相应的对照组。利用神经元特异性标记物MAP2抗体进行免疫荧光染色，计数MAP2阳性细胞的百分比。结果：5Hz和20Hz交变磁场干预1d，均出现对NSC分化方向的显著影响，即促进NSC神经元的分化；20Hz电磁场随干预时程的延长，NSC分化为神经元的比例逐渐增高，以10d组神经元比例最高；5Hz磁场干预5d时神经元比例最高，10d时有所下降，但仍高于对照组；20Hz磁场效应在10d时显著大于5Hz磁场。结论：5Hz和20Hz电磁场以不同的效应模式促进NSC神经元向的分化，电磁场可以成为NSC定向分化研究的重要手段之一。

Effects of Different Frequency Electromagnetic Fields on the Differentiation of Midbrain Neural Stem Cells

Objective. To examine the effect of electromagnetic fields (EMF) (20 Hz, 8 mT; 5 Hz, 8 mT) on the neuron-orientated differentiation of neural stem cells (NSCs) from midbrains of new-bom rats. Method. Differentiated NSCs were exposed to EMF for 2 x 15 min per day lasting for I d, 5 d, or 10 d. The sham-exposure controls were correspondingly established. Cells were fixed and processed for immunofluorescent staining using the antibody against neuron-specific marker MAP2, then the percentage of MAP2+ cells was calculated. Result. The two EMFs promoted the differentiation of a neuronal fate in different ways. Both of them came into effect even after 1 d exposure. When cells exposed to the 20 Hz EMF, the percentage of neuron-orientated cells gradually increased with longer-term exposure and the most significant effect appeared in 10 d group while that happened in 5 d group under the condition of 5 Hz EMF. The effect contrasted horizontally, significant differences between the two EMFs were observed only at 10 d groups, 20 Hz EMF having more favorable effect than 5 Hz EMF. Conclusion. 20 Hz and 5 Hz EMF could promote the differentiation of midbrain NSCs to a neuronal phenotype in different ways, suggesting that the physical induction might be another strategy to manipulate the differentiation of NSCs.