γ-分泌酶抑制剂对高氧暴露致新生鼠脑白质损伤的保护作用  

Effect of γ-secretase inhibitor on hyperoxia-induced brain white matter injury in mice

作　　者：刘光建[1] 蒋朴[2] 杜敏[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墨堕诊治与预防国际科技合作基地,重庆400014 [2]重庆医科大学基础医学院法医学教研室,重庆400016

出　　处：《南方医科大学学报》2015年第9期1287-1292,共6页Journal of Southern Medical University

基　　金：国家临床重点专科建设项目(国卫办医涵[2013]544);青年科学基金(81200440)

摘　　要：目的探讨γ-分泌酶抑制剂(N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester,DAPT)对常压高浓度氧暴露致新生小鼠脑白质损伤中的作用。方法将新生3 d小鼠持续80%高氧暴露48 h,建立新生鼠未成熟高氧脑损伤模型,并于高氧暴露前1 h通过腹腔注射DAPT(10 mg/kg),将小鼠分为空气对照组(C),空气+DAPT组(C+DAPT),高氧组(H),高氧+DAPT组(H+DAPT)。检测第3,5、12及28天各组小鼠的脑质量、体质量;模型制作后48 h RT-PCR检测小鼠脑组织NICD m RNA(Notch intracellular domain)的表达;第12天免疫组化检测NG2和MBP(myelin basic protein)表达;第28天Morris水迷宫评价各组小鼠学习记忆能力。结果与C组比较,H组小鼠随着日龄延长小鼠脑质量、体质量均明显下降(P<0.05);与H组比较,给予DAPT预处理高氧暴露(H+DAPT组)后,小鼠脑质量、体质量显著增加(P<0.05);RT-PCR提示高氧暴露后NICD m RNA表达上调,DAPT可逆转高氧所致脑组织中NICD上调;免疫荧光双标显示H组NG2细胞增多,MBP细胞减少;与H组比较,DAPT预处理后(H+DAPT组)NG2细胞明显减少,MBP细胞明显增多;Morris水迷宫H组与C组比较,逃避潜伏期和游动距离均延长(P<0.05),目标象限停留时间缩短(P<0.05),穿越虚拟平台次数减少(P<0.05);而H+DAPT组与H组比较上述各项指标均明显好转。结论γ-分泌酶抑制剂(DAPT)可抑制高氧暴露所致脑内Notch信号水平的变化,减轻高氧诱导未成熟脑白质损伤,降低新生期高氧暴露对远期学习记忆能力损害。Objective To investigate the effect of γ-secretase inhibitor（N-[N-（3,5-difluorophenacetyl）-l-alanyl]-S-phenylglycine t-butyl ester, DAPT） on hyperoxia-induced brain white matter injury in mice. Methods Three-day-old C57BL/10 J mouse pups were divided into air control（C） group, control＋DAPT（10 mg/kg, injected intraperitoneally） group, hyperoxia group（exposed to 80% oxygen for 48 h）, and hyperoxia ＋ DAPT group. The brain and body weights of the mice were measured at postnatal days 3, 5, 12, and 28. Real-time PCR was used to detect Notch intracellular domain（NICD） m RNA expression in the brain after modeling, and the expressions of NG2 and myelin basic protein（MBP） were detected by double-labeled immunofluorescence assay to verify the oligdendrocycle type at postnatal day 12. The mice in each group were bred until postnatal day 28 for Morris water maze test. Results The brain and body weights were significantly decreased in mice in hyperoxia group compared to the control mice, but increased significantly after DAPT treatment（P〈0.05）. Real-time PCR showed that a 48-hour hyperoxia exposure significantly increased NICD m RNA expression in the brain（P〈0.05）, which was decreased by cotreatment by DAPT（P〈0.05）. Hyperoxia also resulted in enhanced NG2 expression and lowered MBP expression in the brain（P〈0.05）. Compared with the control mice, the mice exposed to hyperoxia showed prolonged escape latency（P〈0.05） and spent less time in the target quadrant with a lowered number of passing through the virtual platform（P〈0.05）. All these parameters were significantly improved by co-treatment with DAPT. Conclusion Specific inhibition of Notch signaling pathway activation in the brain by the γ- secretase inhibitor DAPT can ameliorate white matter injury and learning and memory impairment in newborn mice with hyperoxia exposure.

关 键 词：DAPT Notch信号通路 高氧 脑白质损伤 水迷宫 

分 类 号：R742[医药卫生—神经病学与精神病学]