脑源性促红细胞生成素在新生鼠脑缺氧缺血后海马的表达变化

Expression of brain-derived erythropoietin in hippocampus of neonatal rats with hypoxic-ischemic brain damage

目的探讨新生鼠脑缺氧缺血后海马CA1区脑源性促红细胞生成素(EPO)的表达,揭示脑缺氧缺血后内源性因素启动海马神经发生的可能机制。方法7日龄SD新生大鼠结扎左侧颈总动脉并暴露在低氧环境造成新生大鼠缺氧缺血性脑损伤。选用192只大鼠,96只做免疫组织化学染色,96只做免疫印迹Western blot分析。分别随机分为3组,即正常对照组、单纯缺氧组、缺氧缺血组,每组又分为1h、6h、16h、1d、3d和7d共6个时间点。应用免疫组织化学法和免疫印迹观察海马CA1区脑源性EPO的表达变化。结果单纯缺氧、缺氧缺血EPO的表达与正常对照组比较,差异均有统计学意义;正常对照组各时间点EPO的表达差异无统计学意义,单纯缺氧、缺氧缺血后16h,脑源性EPO表达达到较高水平,与其余时间点比较差异有统计学意义,以后随时间延长逐渐下调。结论脑源性EPO表达在新生鼠脑缺氧缺血后早期即增加,推测低氧、EPO早期高表达可能是参与海马神经发生的内源性因素之一。

Objective To examine the expression of brain-derived erythropoietin in the hippocampus of neonatal rats with hypoxic-ischemic brain damage （HIBD） , and explore the mechanism of neurogenesis in the hippoeampus triggered by endogenous risk factors after HIBD. Methods One hundred and ninety-two 7-day-old Sprague-Dawley （SD） rats were studied： 96 underwent immunohistochemical staining, and 96 used for Western blot analysis. All the SD rats were randomly divided into three groups： control （C）, hypoxia （H） and hypoxia-ischemia （HI） groups. In 64 rats （ 13 to 19 g of body weight） left common carotid artery was ligated, then exposed to hypoxic condition to establish the model of neonatal HIBD. Each group was assessed at 1 h, 6 h, 16 h, 1 d, 3 d and 7 d time points. Four rats from C group, 4 rats from H group, and 8 rats of HI group were examined at every time point. Immunohistochemical staining and Western blot were used to identify the expression of brain-derived erythropoietin in the hippocampal CA1 at every time point after HIBD. Results There was a significant difference in the expression of brain-derived erythropoietin among three groups, and most significant changes were found in HI group. The changes at different time points in C group were not significant. The expression changed with time in H and HI groups： first detected in hippocampal CA1 region at 1 h after HIBD, reached peak level at 16 h after HIBD, and then decreased after that. Conclusions The expression of braln-derived erythropoietin increased early after hypoxia. Hypoxia, overexpression of erythropoietin at that time was probably one of endogenous factors involved in the neurogenesis in neonatal hippocampus after HIBD.