中文摘要：

目的探讨脂多糖（LPS）诱导小胶质细胞（MG）激活导致少突胶质细胞（OL）前体死亡的信号转导通路及LPS诱导MG激活的跨膜转导机制。方法取2日龄Toll样受体4（TLR4）基因缺失小鼠和野型小鼠脑内MG和OL前体共培养,分别分为共培养对照组和共培养LPS组。经LPS100 mg.L-1诱导48 h后,各组共培养细胞,应用硝酸还原酶-比色法检测其一氧化氮（NO）水平、还原-比色法检测其超氧阴离子（O2-）水平,免疫荧光染色法检测其过氧亚硝酸盐（ONOO-）水平,Hochest33342/碘化丙啶荧光染色法观察细胞死亡的形态学改变,流式细胞仪检测其细胞凋亡率。结果 LPS诱导引起野型小鼠共培养细胞内NO和ONOO-水平显著增加,OL前体坏死和凋亡率明显增高。但LPS诱导对TLR4基因缺失小鼠共培养细胞内NO和ONOO-水平以及OL前体坏死及凋亡率均无明显影响。2种小鼠共培养细胞内O2-水平在LPS的诱导下均显著提高。结论 LPS诱导MG激活的跨膜转导机制以及导致OL前体死亡的信号转导通路,必须依赖TLR4的介导。LPS诱导共培养细胞内O2-水平增加可能通过其他非TLR4受体依赖途径。

英文摘要：

Objective To explore the signaling pathway of lipopolysaccharide（LPS）-induced activated microglia（MG） to preoligodendrocytes（pre-OLs） death and the mechanism of transmembrane conduction in LPS-induced microglial activation.Methods The co-cultured MG and pre-OLs obtained from 2-day-old Toll-like receptor 4（TLR4）-deficient mice and wild-type mice were divided into the co-cultured control group and the co-cultured LPS group,respectively.The concentration of nitric oxide（NO） was measured with nitric acid-deoxidize colorimetry,the level of O2-was determined with deoxidize colorimetry,the level of peroxynitrite（ONOO-） was detected with immunocytochemistry,the morphologic observation of death pre-OLs was stained with Hochest33342/propidium iodide and the apoptotic rate of pre-OLs was detected with flow cytometry,after the co-cultured cells induced by LPS（100 mg·L-1） for 48 h.Results Compared with the co-cultured control group of wild-type mice,there was an obvious increase in levels of NO and ONOO-with an increased necrotic pre-OLs and higher apoptotic rate of pre-OLs in the co-cultured LPS group of the wild-type mice.However,there was no significant influence of LPS induction on NO level and ONOO-level,and the apoptotic rate of pre-OLs was observed in the co-cultured LPS group of TLR4-deficient mice.The obvious increase of O2-concentration induced by LPS in co-cultured cells was observed in either the wild-type mice or the TLR4-deficient mice.Conclusions The existence of TLR4 is necessary to mediate either transmembrane conduction of LPS-induced microglial activation or the signaling pathway of LPS-induced activated-MG to pre-OLs death.The increase of O2-concentration induced by LPS in co-cultured cells is speculated by through other non-TLR4 receptor-dependent way probably.