常氧和低氧条件下介导神经干细胞增殖的信号通路分析

Signaling pathway analysis on the proliferation of neural stem ceils in both normoxia and hypoxia

目的：观察常氧和低氧环境下大鼠大脑皮层神经干细胞（NSCs）体外增殖情况，并比较P13K／Akt、JNK和Notch3条信号通路在不同氧环境下NSCs增殖时所发挥作用的异同。方法：在常氧和4％02浓度下悬浮培养新生SD大鼠大脑皮层NSCs，在培养细胞24、36和48h时使用图像分析软件测量NSCs增殖后所形成的神经球直径。结果：在培养细胞24、36和48h后，在不同时间段低氧组神经球直径都大于常氧对照组；在常氧浓度环境下分别使用0．5％DMSO和10μmol／LLY294002（P13K／Akt抑制剂）、SP600125（JNK抑制剂）和DAPT（Notch抑制剂）培养细胞，在培养细胞36h和48h时，3个抑制剂组神经球直径都小于常氧DMSO对照组。在低氧浓度环境下培养细胞36h和48h时，LY294002和SP600125组神经球直径与低氧DMSO组相比均无差异，而DAPT组神经球直径明显小于低氧DMSO对照组。结论：P13K／Akt、JNK和Notch3条信号通路均介导了常氧浓度环境下NSCs增殖，但低氧浓度环境诱导的NSCs增殖主要由Notch信号通路介导。

Objective： To observe the cell proliferation of the cerebral cortex in newborn SD rats under normoxia and hypoxia, and to compare the roles of three signaling pathways including PI3K/AKT, JNK and Notch in the proliferation under normoxia and hypoxia. Methods： The neural stem cells （NSCs） of the cerebral cortex in newborn SD rats were isolated and cultured under normal and 4% oxygen concentration. Each group was mixed with DMSO/LY294002/SP600125/DAPT, and then the diameters of neurospheres were measured at 24 h/36 h/48 h using the image analysis software. Results： The diameters of neurospheres under hypoxia were greater than those of normorxia at 24 h/36 h/48 h. The diameters of neurospheres treated with 0. 5%DMSO, LY294002 （inhibitor of PI3K/Akt）, SP600125 （inhibitor of JNK）, DAPT（inhibitor of Notch） under normal oxygen were smaller than those of DMSO group in normal oxygen. The diameters of neurospheres treated with LY294002/SP600125 had no significance difference compared to the DMSO group, but the diameters of neurospheres treated with DAPT were much smaller than those of the DMSO group. Conclusion： PI3-K/Akt, JNK and Notch signaling pathway all play important roles in the proliferation of NSCs, but Notch pathway mainly regulates the proli{eration of NSCs induced by hypoxia.