中文摘要：

【摘要】目的观察黄芩苷促进神经干细胞（NSCs）体外向神经元分化过程中信号传导子与转录激活子（STAT）的磷酸化蛋白表达水平。方法从孕14—15d的SD大鼠胚胎大脑皮质中分离NSCs，体外培养传代，实验用第3代NSCs。随机分为对照组，低、中、高黄芩苷组（分别含黄芩苷7．5、15、30μmol／L），白血病抑制因子（ELF）＋碱性成纤维细胞生长因子（bFGF）组和黄芩苷＋LIF＋bFGF组。培养6d后，细胞免疫荧光化学染色法观察各组中微管相关蛋白2（MAP-21、胶质纤维酸性蛋白（GFAP）表达水平。培养2h与6d后，用Westernblot方法观察各组中STAT3蛋白磷酸化水平。结果黄芩苷可使NSCs中MAP-2表达增加，GFAP表达减弱；LIF＋bFGF可促进NSCs中GFAP表达增加；黄芩苷可抑制LIF＋bFGF引起的NSCs中GFAP的表达增加。黄芩苷可下调NSCs中STAT3蛋白磷酸化水平；LIF＋bFGF可上调NSCs中STAT3蛋白磷酸化水平；黄芩苷可抑制LIF＋bFGF引起的NSCs中STAT3蛋白磷酸化水平的上调（P〈0．05）。结论黄芩苷可诱导NSCs向神经元分化并抑制其向星形胶质细胞分化，该作用可能经下调NSCs中STAT3的磷酸化水平来实现。

英文摘要：

Objective To observe the role of baicalin on the expression of phosphorylated protein of signal transduc- ers and activators of transcription signaling proteins （STATs） during the process that neural stem cells （NSCs） differentiating into neurons. Methods NSCs were isolated from the embryonic cerebral cortex of the 14-15-day pregnant SD rats, which were cultured and passaged in vitro. The 3rd generation of NSCs was used in the experiment. NSCs were randomized into nat- ural differentiation control group, three different doses of baicalin groups （7.5μmol/L, 15 μmol/L and 30μ mol/L）, leukemia inhibitory factor （LIF） ＋ basic fibroblast growth factor （bFGF） group and baicalin ＋ LIF ＋ bFGF group. After 6 d culture in vi- tro, the immunohistochemical method was used to observe the expressions of microtubule-associated protein 2（MAP-2） and glial fibrillary acidic protein （GFAP） in different groups. The expression levels of phosphorylation protein of STAT3 in NSCs were detected by Western blotting method after 2 h and 6 d of culture. Results The expression of MAP-2 in NSCs was in- creased by baicalin, but the expression of GFAP in NSCs decreased. The expression of GFAP in NSCs was enhanced in LIF＋ bFGF group, which was inhibited by baicalin ＋ LIF ＋ bFGF. The phosphorylation level of STAT3 in NSCs was downregulat- ed by baicalin, but the phosphorylation level of STAT3 was upregulated in LIF＋ bFGF group. The upregulated phosphoryla- tion level of STAT3 was inhibited in baicalin ＋ LIF ＋ bFGF group（P 〈0.05）. Conclusion Baicalin can induce NSCs to dif- ferentiate into neurons, which may be caused by the downregulation of the phosphorylation level of STAT3 in NSCs.