摘要： 研究背景 颅脑创伤后的炎症反应可导致继发性脑损伤，引起神经元凋亡和神经功能缺损。重组人红细胞生成素（rhEPO）具有神经保护作用，我们采用液压打击动物模型，观察经rhEPO 治疗后脑组织中性粒细胞变化和神经元凋亡情况，以探讨该药对颅脑创伤后神经功能保护的潜在作用机制。方法 采用液压打击模型模拟颅脑创伤，分别于创伤后第1 、3 和7 天观察不同处理组小鼠海马区髓过氧化物酶阳性中性粒细胞和Caspase-3 阳性神经元表达变化；并于创伤后第7 ~ 11天进行Morris 水迷宫实验，记录小鼠逃避潜伏期。结果 与假手术组相比，伤后第1 天小鼠海马区髓过氧化物酶阳性中性粒细胞数目即开始增加（均P = 0.000），并于第 3 天达峰值水平（均P = 0.000），至第7 天时减少（均P =0.000）；Caspase-3 阳性神经元数目于伤后第1 天开始逐渐增多（均P = 0.000），至第7 天达峰值水平（均P = 0.000）。与生理盐水组相比，rh EPO 组小鼠伤后第1 ~ 7 天海马区髓过氧化物酶阳性中性粒细胞和Caspase-3 阳性神经元数目呈逐渐减少趋势，不同观察时间点差异具有统计学意义（均P = 0.000）。与生理盐水组相比，rhEPO 组小鼠于Morris 水迷宫实验训练第3 天逃避潜伏期开始缩短（P = 0.013），随着训练时间的延长，组间差异具有统计学意义（P = 0.011，0.000）。结论 液压打击后给予rhEPO 可促进小鼠颅脑创伤后认知功能的恢复。其可能机制与抑制创伤后局部炎症反应、减少神经元凋亡、促进神经功能恢复有关。

关键词: 脑损伤, 红细胞生成素, 重组, 过氧化物酶类, 半胱氨酸天冬氨酸蛋白酶3 , 细胞凋亡, 认知障碍, 疾病模型, 动物

Abstract: Background Inflammation after traumatic brain injury (TBI) could exacerbate secondary brain injury, resulting in neuronal apoptosis and neurological deficit. It is confirmed that recombinant human erythropoietin (rhEPO) plays an important role in neuroprotection after brain injury. This article discusses the potential mechanism of rhEPO therapy that promotes the neurological function recovery after TBI by observing the changes of neutropils and neuronal apoptosis in the brain tissue of mice after fluid percussion injury (FPI). Methods Adult male C57BL/6 mice were randomly divided into 4 groups: Sham group, TBI group, rhEPO group and normal saline (NS) group. On the first, third and seventh days after FPI, 3 mice were randomly taken from each group, the brain tissue of which was obtained. Then, immunohistochemistry was adopted to observe the expression of myeloperoxidase (MPO) positive neutrophils and Caspase-3 positive neuronal cells in the hippocampal area. During seventh to eleventh day after FPI, 10 mice of each group were subjected to Morris Water Maze Test and escaping latencies were recorded. Results Compared to Sham group, the number of MPO positive neutrophils began increasing from the first day after FPI (P = 0.000, for all) and reached the peak on the third day ( P = 0.000, for all) in the TBI group, NS group and rhEPO group, but reduced on the seventh day (P = 0.000, for all); whereas Caspase-3 positive neurons increased significantly 1 d after FPI, peaking on the seventh day. However, the increase of MPO positive cells and Caspase-3 positive neurons in rhEPO group was not obvious. Compared to NS group, MPO positive neutrophils and Caspase-3 positive cells reduced significantly in rhEPO group (P = 0.000, for all) 1 to 7 d after FPI in the observed time points. In the Morris Water Maze (MWM), the latency of mice in rhEPO group reduced as compared to the NS group from the third day after FPI (P = 0.013). The differences were statistically significant as time went on (P = 0.011, 0.000). Conclusion The cognition recovery of mice after FPI can be promoted by rhEPO treatment, the potential mechanism of which is related to reducing inflammation and neuron apoptosis and promoting neural function recovery.

Key words: Brain injuries, Erythropoietin, recombinant, Peroxidases, Caspase 3, Apoptosis, Cognition disorders, Disease models, animal