Abstract: Objective To analyze the protective effect and possible mechanism of delayed mild hypothermia on white matter injury in oxygen-glucose deprivation and restoration newborn rats. Methods The models of whole brain perfusion and oxygen glucose deprivation were established in 40 neonatal rat pups. Forty neonatal rats were randomly divided into four groups and treated with mild hypothermia (32 ℃) for 0 h, 24 h, 48 h, 72 h, with 10 rats in each group. The expression of myelin basic protein (MBP) was detected by Western Blot.The expression of microglia was identified by immunofluorescence.The concentrations of TNF-α and IL-6 were determined by ELISA. Results The level of MBP protein expression at 32 ℃ for 24 h, 48 h and 72 h was significantly higher than that at 0 h in the control group (F=478.007, t=-18.180、22.940,-29.670,P＜0.001), and there was a significant positive correlation between the protein expression level and the duration of delayed mild hypothermia.With the extension of delayed mild hypothermia time, the activation degree of microglia was inhibited. The number of Iba-1 positive cells at 24 h, 48 h and 72 h was significantly lower than that at 0 h in control group (F=99.892, t=5.879, 9.295, 18.760,P＜0.001), showing that increased fluorescence expression level was negatively correlated with delayed mild hypothermia time. The concentrations of TNF-α and IL-6 were significantly lower than those of the control group at 0 h (TNF-α:F=454.197, t=2.184, 15.300, 15.000, P＜0.05;IL-6:F=123.995, t＝5.650,13.120, 13.910, P＜0.001), indicating that the concentrations of IL-6 was negatively correlated with the time of delayed hypothermia. Conclusion Delayed mild hypothermia can protect the white matter injury of oxygen-glucose deprivation and reoxygen-glucose newborn mice, and its mechanism may be related to inhibiting microglial cell activation and down-regulating inflammatory response.

Key words: newborn mice, mild hypothermia, microglial cell, inflammatory factor, white matter injury, myelin basic protein

摘要： 目的 探讨延迟亚低温保护氧糖剥夺-复氧复糖新生幼鼠脑白质损伤的效果及可能机制。方法 建立40只新生幼鼠全脑灌流和氧糖剥夺模型,随机均分为4组每组10只,分别进行亚低温32 ℃延迟0 h、24 h、48 h、72 h干预。用Western Blot检测髓鞘碱性蛋白(MBP)的蛋白表达情况;用免疫荧光鉴定小胶质细胞的表达情况;用ELISA测定TNF-α、IL-6浓度情况。结果 在亚低温32 ℃延迟24 h、48 h和72 h的MBP蛋白表达均显著高于对照组0 h(F=478.007,t=-18.180、22.940、-29.670,P＜0.001),可发现蛋白表达量与延迟亚低温时长呈显著正相关;随着延迟亚低温时间的延长,小胶质细胞活化程度受到抑制,24 h、48 h和72 h的Iba-1阳性细胞比例均显著低于对照组0 h(F=99.892,t=5.879、9.295、18.760,P＜0.001),可发现荧光表达增高与延迟亚低温时间呈显著负相关;TNF-α、IL-6浓度均较对照组0 h显著降低(TNF-α:F=454.197,t= 2.184、15.300、15.000,P＜0.05;IL-6:F=123.995,t=5.650、13.120、13.910,P＜0.001),可发现IL-6浓度与延迟亚低温时间呈负相关。结论 延迟亚低温能保护氧糖剥夺-复氧复糖新生幼鼠脑白质损伤,其机制可能与抑制小胶质细胞活化和下调炎症反应有关。

关键词: 新生幼鼠, 亚低温, 小胶质细胞, 炎症因子, 脑白质损伤, 髓鞘碱性蛋白