Sun Yun, Zhou Changman, Polk Paula, Nanda Anil, Zhang John H
Department of Neurosurgery, Louisiana State University Health Sciences Center in Shreveport, 71130, USA.
J Cereb Blood Flow Metab. 2004 Feb;24(2):259-70. doi: 10.1097/01.WCB.0000110049.43905.AC.
Erythropoietin, a hemotopoietic growth factor, has brain protective actions. This study investigated the mechanisms of Recombinant Human EPO (rhEPO)-induced brain protection in neonates. An established rat hypoxia-ischemia model was used by ligation of the right common carotid artery of 7-day-old pups, followed by 90 minute of hypoxia (8% 02 and 92% N2) at 37 degrees C. Animals were divided into three groups: control, hypoxia-ischemia, and hypoxia-ischemia plus rhEPO treatment. In rhEPO treated pups, 300 units rhEPO was administered intraperitoneally 24 hours before hypoxia. rhEPO treatment (300 units) was administered daily for an additional 2 days. ELISA and immunohistochemistry examined the expression of EPO and EPOR. Brain weight, morphology, TUNEL assay, and DNA laddering evaluated brain protection. rhEPO abolished mortality (from 19% to 0%) during hypoxia insult, increased brain weight from 52% to 88%, reduced DNA fragmentation, and decreased TUNEL-positive cells. Real-time RT-PCR, Western blot, and immunohistochemistry revealed an enhanced expression of heat shock protein 27 (HSP27) in ischemic brain hemisphere. Double labeling of TUNEL with HSP27 showed most HSP27 positive cells were negative to TUNEL staining. rhEPO reduces brain injury, especially apoptotic cell death after neonatal hypoxia-ischemia, partially mediated by the activation of HSP27.
促红细胞生成素是一种造血生长因子，具有脑保护作用。本研究探讨重组人促红细胞生成素（rhEPO）对新生儿脑保护的机制。采用结扎7日龄幼鼠右侧颈总动脉建立大鼠缺氧缺血模型，随后在37℃下进行90分钟的缺氧（8%氧气和92%氮气）。动物分为三组：对照组、缺氧缺血组和缺氧缺血加rhEPO治疗组。在rhEPO治疗的幼鼠中，在缺氧前24小时腹腔注射300单位rhEPO。rhEPO治疗（300单位）每天额外给药2天。采用酶联免疫吸附测定（ELISA）和免疫组织化学检测EPO和EPOR的表达。通过脑重量、形态学、TUNEL检测和DNA梯状条带分析评估脑保护作用。rhEPO消除了缺氧损伤期间的死亡率（从19%降至0%），使脑重量增加了52%至88%，减少了DNA片段化，并减少了TUNEL阳性细胞。实时逆转录聚合酶链反应（RT-PCR）、蛋白质免疫印迹法（Western blot）和免疫组织化学显示缺血脑半球中热休克蛋白27（HSP27）表达增强。TUNEL与HSP27的双重标记显示，大多数HSP27阳性细胞对TUNEL染色呈阴性。rhEPO可减轻新生儿缺氧缺血后的脑损伤，尤其是凋亡性细胞死亡，部分是由HSP27的激活介导的。
