RESUMO
Objective To study the regulatory effects of microRNA-200b (miR-200b) on hypoxia-inducible factors-1α (HIF-1α） in neonatal immature rats with hypoxic-ischemic brain damage (HIBD).Method A total of 240 three-day-old neonatal Sprague-Dawley (SD) rats were randomly assigned into six groups with 40 rats in each group:the hypoxic-ischemic group (HI group),intraventricular injection of miR-200b agomir,intraventricular injection of miR-200b antagomir,intraventricular injection of agomir negative control group,intraventricular injection of antagomir negative control group and the normal control group.The HIBD models of immature neonatal rats were established except for the normal control group.The relative expressions of HIF-1 α in brain tissues of each group were detected using quantitative real-time-PCR at 12 h,1 d,3 d and 7 d after ventricular injection,and the changes of HIF-1α expression in each group were compared.Result (1) Compared with the control group,the expression of HIF-1oα of the HI group began to increase 12 h after the injection of normal saline into the lateral ventricle (P＜0.05),and reached the peak at 1d,with statistically significant difference (P＜0.05),and then gradually decreased to the normal control group level at 7 d.(2) No significant differences of HIF-1α existed among the HI group and the HI+ agomir negative control group and the HI + antagomir negative control group (P＞0.05),and the miR-200b carrier had no significant effects on the expression of HIF-1α.(3)HIF-1α continued to be highly expressed after the injection of antagomir into the lateral ventricle of HI,and was significantly higher than the HI group at 12 h (P＜0.05).No significant differences existed between the HI+antagomir group and the H1 group at 1 d,3 d and 7 d after antagomir injection (P＞0.05).The expression of HIF-1α was constantly lower than the HI group after the injection of agomir,and significantly lower than the HI group at 1d after injection (P＜0.05).Conclusion MiR-200b overexpression inhibits the expression of HIF-1α,and the low expression of miR-200b can increase the level of HIF-1oα in a limited time window.Therefore,miR-200b may participate in the regulation of brain injury in neonatal rats after HIBD by regulating the expression of HIF-1α.