Objective To investigate the protective effect of inhibition of hypoxia inducible factor－1 alpha (HIF－1α) and activation of Wnt signaling pathway on brain injury in neonatal rats.Method A total of 312 newborn SD rats were used to establish cerebral white matter damage model (WMD) on day 3.And they were randomly assigned into the model group (WMD group), post－modeling HIF－1αdecomposition inhibition group (PHI group), and post－modeling HIF－1αdecomposition inhibition with activation of Wnt signaling pathway group (PHI+activated Wnt group ) and post－modeling HIF－1αdecomposition inhibition with inhibition of the Wnt signaling pathway group (PHI+inhibition Wnt group).Brain tissues were taken on day 1, 3, 7 and 14 after modeling, respectively.The changes of oligodendrocyte precursor cell (OPC) and oligodendrocyte ( OL ) in brain tissues at different time points were observed by tissue immunofluorescence.The expression of HIF－1αprotein in the brain tissue of each time point was measured by western blot technique.The mRNA level of HIF－1αand Wnt7a in the brain tissue of each time point was detected by RT－qPCR technique.Behaviors of rats were tested by the suspension experiment , the open field experiment and the dark experiment , at 28 d after modeling.Result The numbers of OPC on 1 d and 3 d after modeling and the number of OL on 7 d and 14 d after modeling in PHI +activated Wnt group were significantly higher than the other three groups.The content of HIF－1αin WMD group was the least on 1, 3, 7 and 14 d, but the content of PHI+activated Wnt group was the highest , and the difference was statistically significant (P＜0.05).On 1, 3, 7 and 14 d after modeling, the expression level of HIF－1αand Wnt7a in PHI+activated Wnt group were higher than those in the other three groups , the difference was statistically significant (P＜0.05), and Wnt7a expression was positively correlated with the change of HIF－1α(P＜0.05).There was no significant difference of suspension experiment at 28 d after modeling between groups. Compared with other groups , WMD group had the lowest score on open field experiment ( P＜0.05).The PHI+activation Wnt group had better memory function , and then the PHI group , WMD group.The latent time of dark experiment were significantly shorter in PHI +acitivation Wnt group.There were more mistaken time of dark experiment in WMD group compared with PHI +activation Wnt group.Conclusion Inhibition of HIF－1αdecomposition and activation of Wnt signaling pathway have partially repair effect on brain injury in neonatal rats.%目的 探讨抑制低氧诱导因子1α(hypoxia inducible factor－1 alpha,HIF－1α)、激活Wnt信号通路对新生大鼠脑损伤是否有保护作用.方法 选取312只3日龄新生SD大鼠建立脑白质损伤(white matter damage,WMD)模型,随机分为单纯造模组(WMD组)、造模后抑制HIF－1α分解组(PHI组),造模并抑制 HIF－1α分解后激活 Wnt 信号通路组(PHI +激活 Wnt 组)及造模并抑制HIF－1α分解后抑制Wnt信号通路组(PHI+抑制Wnt组).分别于造模后1、3、7、14 d取脑组织,采用免疫荧光法观察各组各时间点脑组织前体细胞( oligodendrocyte precursor cell ,OPC)及少突胶质细胞(oligodendrocyte,OL)的变化;采用免疫印迹技术测定各组各时间点脑组织HIF－1α蛋白表达情况;通过实时荧光定量聚合酶链反应技术检测各组各时间点脑组织HIF－1α及Wnt7a mRNA水平.于造模后28 d通过悬吊实验、旷场实验、避暗实验对各组大鼠进行行为学检测.结果 PHI+激活Wnt组造模后1、3 d时OPC与造模后7、14 d时OL数量均明显多于其他3组.与WMD组相比,其他3组各时间点脑组织HIF－1α蛋白含量、HIF－1α与Wnt7a mRNA表达量均明显增加,尤其PHI+激活Wnt组,差异有统计学意义(P＜0.05). Wnt7a表达与HIF－1α表达成正相关(r＝0.862,P＜0.05).造模后28 d各组大鼠悬吊实验评分差异无统计学意义(P＞0.05);WMD组大鼠旷场实验评分低于其他3组,差异有统计学意义(P＜0.05);PHI+激活Wnt组大鼠记忆保留程度最高,PHI组次之,WMD组最低,WMD组、PHI组及PHI+抑制Wnt组大鼠第1次进入暗箱的时间(潜伏期)均短于PHI+激活Wnt组,WMD组进入暗箱的次数(错误次数)大于PHI+激活Wnt组,差异有统计学意义( P＜0.05).结论 抑制HIF－1α分解并激活Wnt信号通路对新生大鼠脑损伤有部分修复作用.
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