小胶质细胞在高氧暴露未成熟脑损伤中的作用  

The effects of microglia on hyperoxia-induced immature brain damage of newborn mice

作　　者：杜敏[1] 刘扬[1] 蒋朴[2] 彭玲珑 郭冉[1] 刘光建[1] 徐颖[1] 

机构地区：[1]重庆医科大学附属儿童医院麻醉科儿童发育疾病研究教育部重点实验室儿科学重庆市重点实验室重庆市儿童发育重大疾病诊治与预防国际科技合作基地,400014 [2]重庆医科大学基础医学院法医学教研室,400016

出　　处：《免疫学杂志》2014年第12期1069-1072,1086,共5页Immunological Journal

基　　金：中国博士后基金(20090450790)

摘　　要：目的观察新生小鼠高氧暴露后,小胶质细胞功能变化及未成熟脑内NG2细胞的凋亡情况,以探讨小胶质细胞在高氧未成熟脑损伤中的作用。方法将新生3 d(PND3)小鼠持续90%高浓度氧暴露48 h,建立新生鼠未成熟脑高氧脑损伤模型,并腹腔注射小胶质细胞活化抑制剂米诺环素,将小鼠分为对照(A)组,空气+米诺环素(AM)组,高氧(O)组和高氧+米诺环素(OM)组,其中AM组和OM组给予45 mg/kg米诺环素。免疫组化观察小胶质细胞活化情况,real-time PCR检测TLR4(Toll样受体4,Toll-like receptor 4)、TNF-α(tumor necrosis factor-α)表达水平。免疫荧光双标检测凋亡蛋白Caspase-3表达及NG2细胞(未成熟少突胶质细胞)凋亡情况。结果与A组比较,O组激活状态的小胶质细胞明显增多,TLR4表达上调。免疫荧光结果显示O组脑组织中凋亡细胞明显增多,且免疫荧光双标可见NG2与Caspase-3共表达。而与O组相比,OM组TLR4和TNF-α的表达明显降低(P<0.05),且Caspase-3表达及NG2细胞凋亡明显减少。结论围生期常压高浓度氧暴露通过激活小胶质细胞上调TLR4表达引起炎症反应致未成熟脑细胞凋亡,凋亡细胞包括少突胶质祖细胞(NG2+);抑制小胶质细胞活化可明显减轻高氧未成熟脑损伤。This study design ed to investigate the role of microglia in hyperoxia-induced immature brain damage in newborn mice. Three-day-old C57BL/10 J mouse pups were subjected to 90% oxygen for 48 h to construct hyperoxia-induced immature brain damage model. Mice divided into control group（A）, minocycline（AM）group, hyperoxia group（O） and hyperoxia＋minocycline（OM） group, while AM and OM groups were treated with 45 mg/kg minocycline. Immunohistochemical method was used to observe the activation of microglia; real-time PCR was applied to test the expression of TLR4 and TNF-α at m RNA level. The expressions of Caspase-3 and NG2 were detected by double-labeled immunofluorescence assay to make sure the apoptotic cell type. Data showed as compared with control group, there were more activated microglia and upregulated TLR4 expression in hyperoxia group; immunofluorescence assay showed there was more expression of Caspase-3 in hyperoxia group compared with control group; and co-expression was observed in double-labeled immunofluorescence（Casapase-3 and NG2）. Furthermore, the use of minocycline reduced the expression of TLR4（P 〈 0.05）, TNF-α（P 〈 0.05） and Caspase-3. All these results indicated that hyperoxia exposure activates microglia, upregulates TLR4 expression and induces inflammation, thus mediates immature neurocyte apoptosis, in which oligodendrocyte progenitor cells（OPCs, NG2＋） are the main apopto tic cell type. Therefore, inhibiting the activation of microglia can reduce the inflammation and apoptosis induced by hyperoxia in immature brain.

关 键 词：高氧 未成熟脑损伤 小胶质细胞 TLR4 

分 类 号：R722.6[医药卫生—儿科]