铝对大鼠神经干细胞向神经元细胞分化的影响

Effects of aluminum on differentiation of rat neural stem cell into neuron-like cells

目的探讨铝对大鼠神经干细胞向神经元样细胞分化的影响。方法取孕12～12.5dSD大鼠胚胎的大脑皮层细胞体外培养,建立神经干细胞模型。用Nestin免疫细胞化学法鉴定神经干细胞,在细胞对数增长期加入不同浓度的AlCl3(400、200、100μmol/L),接触24h后,用DMEM(含1%B27)培养基培养7d,免疫细胞化学染色比较各组MAP2阳性细胞率。用生物图像处理系统(包括NikonE800u显微镜,Spot2冷彩色数码摄像系统,MetaMorph图像分析软件)分析神经元树突分枝的数量和MAP2阳性细胞光密度(OD)值。结果与对照组相比,100μmol/LAlCl3组神经干细胞分化为MAP2阳性细胞率(%)、神经元树突分枝和MAP2阳性细胞光密度值均没有明显差异(P=0.082,P=0.117,P=0.086),但200μmol/L和400μmol/LAlCl3组与对照组相比均有明显降低(P<0.01),并且有良好的剂量-反应关系。结论AlCl3不仅能够抑制大脑神经干细胞向神经元样细胞分化,还减少了神经元分枝和延缓了其成熟。这可能在铝导致的神经发育毒性作用中起重要的作用。

Objective To investigate the effects of aluminumon differentiation of rat neural stem cells in vitro. Methods The neural stem cells derived from 12～12.5 d embryonic rat cortex were planted in suspended condition (three-dimension) and on coverslip precoated with poly -L-lysine. Neural stem cells were identified by Nestin immunohistochemistry. The cells were exposed to various concentrations of AlCl_3(400,200,100 μmol/L) for 24 h in their logarithmic growth period,processed for immunohistochemi stry staining after one week culture, and the formation rates of MAP2-positive cells among the experimental groups were compared. The neuron dendritic branches and optical density of MAP2-positive cells were detected using MataMorph. Results No significant differences in the formation rate of MAP2-positive cells, neuron dendritic branches and optical density of MAP2-positive cel ls were found between the 100 μmol/L AlCl_3 and control group (P=0.082, P=0.154,P=0.086), but the formation rate of MAP2-positive cells, neuron dendritic branches and optical density of MAP2-positive cells were markedly de creased in 200 μmol/L and 400 μmol/L AlCl_3 groups(P<0.01), and there was a good dose-response relationship. Conclusions The results indic ate that the middle and high concentrations of AlCl_3 can inhibit differentrati on of neural stem cell into neuron-like cells, and decrease neuronal connectivity, which may play an important role in the mechanisms of aluminum neurodevelopm ental toxicity.