氙气对脑白质损伤新生大鼠脑组织EphB4和EphrinB2mRNA表达的影响

Effects of xenon on the expression of EphB4 and EphrinB2 mRNA in neonatal rats with white matter damage

目的 探讨脑白质损伤（white matter damage,WMD）的发病机制及氙气干预对新生大鼠脑组织EphB4和EphrinB2 mRNA表达的影响.方法 将96只3日龄SD大鼠随机分为假手术组、模型组、氙气干预1组和氙气干预2组各24只.模型组和2个氙气干预组采用腹腔注射脂多糖0.05 mg/kg联合右侧颈动脉结扎低氧处理1h建立WMD模型.氙气干预1组于建模后即刻、氙气干预2组于建模后2h吸入50％氙气3h.氙气干预完成后,各组均于0、24、48h和72h各取6只大鼠处死,进行脑室周围白质组织苏木精-伊红染色,采用实时定量聚合酶链反应法测定脑组织EphB4和EphrinB2 mRNA表达水平并进行统计学分析.结果 （1）模型组脑白质结构疏松,呈网状,可见较多细胞核固缩;氙气干预1组与2组24、48h和72h脑组织病理损伤程度均较模型组减轻,可见部分核固缩.（2）与假手术组比较,除72 h氙气干预1组EphB4 mRNA表达量未显著增加外,模型组、氙气干预1组和2组在各时间点EphB4及EphrinB2 mRNA表达量均显著增加,差异有统计学意义（P＜0.05）;与模型组相比,除72 h氙气干预2组EphB4 mRNA表达量未显著减少外,氙气干预1组和2组各时间点EphB4及EphrinB2 mRNA表达量均显著减少,差异有统计学意义（P＜0.05）;氙气干预1组与2组比较,各时间点两指标差异均无统计学意义（P＞0.05）.结论 新生大鼠WMD后脑组织EphB4和EphrinB2 mRNA表达明显增加,提示可能有反应性新生血管生成;氙气干预可发挥神经保护作用,减少EphB4和EphrinB2 mRNA表达及血管新生,早期干预可能效果更佳.

Objective To investigate the pathogenesis of white matter damage （WMD） and the effects of xenon intervention on the expression of EphB4 and EphrinB2 mRNA in the brain tissue of neonatal rats.Method Three-day-old SD rat pups （n =96） were randomly assigned into sham group （n =24）,model group （n =24）,xenon intervention group 1 （n =24） and xenon intervention group 2 （n =24）.The WMD model was established by injected of lipopolysaccharide （LPS） 0.05 mg/kg combined with ligation of the right carotid artery for 1 h in the last three groups.Rats in xenon intervention group 1 inhaled 50% xenon immediately for 3 h after modeling,while rats in xenon intervention group 2 inhaled 50% xenon for 3 h at 2 h after modeling.After the completion of xenon intervention,6 rat pups in each groups were sacrificed at 0 h,24 h,48 h and 72 h.The pathologic examination of periventricular tissue was conducted with hematoxylin-eosin staining （HE） and the expression of EphB4 and EphrinB2 mRNA was assayed by real-time quantitative polymerase chain reaction （RT-PCR）.Statistical analysis was then performed.Result （1）The structure of white matter in model group became loose,band net-like,with significant nucleus pyknosis.The pathological damages in xenon intervention group 1 and 2 were lighter at 24 h,48 h and 72 h than model group,with less karyopycnosis.（2） Compared with the sham group,the expressions of EphB4 and EphrinB2 mRNA at 0 h,24 h,48 h and 72 h were significantly higher in the model group and xenon intervention group 1 and 2 （P 〈 0.05）,except for the EphB4 mRNA in xenon intervention group 1 at 72 h （P 〉 0.05）.The expressions of EphB4 and EphrinB2 mRNA at each time point in xenon intervention group 1 and 2 were decreased significantly than the model group （P 〈 0.05）,except for the EphB4 mRNA in xenon intervention group 2 at 72 h （P 〉 0.05）.However,there was no statistically significant difference on EphB4 and EphrinB2 mRNA between two xenon intervention groups at each time point （P 〉 0.05）.Conclusion The expression of EphB4 and EphrinB2 mRNA are appreciably increased in brain tissue of neonatal rats with WMD,which indicates the reactive angiogenesis.The intervention with xenon may play a neuroprotective role through reducing the expressions of EphB4/EphrinB2 mRNA and angiogenesis,and early intervention may be better.