重组人红细胞生成素改善小鼠颅脑创伤后认知功能的机制探讨

The potential mechanism of recombinant human erythropoietin treatment in vivo promoting the cognitive function recovery after traumatic brain injury in mice

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l、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，rhEPO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。

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 artiele 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, TB] 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, immunohistoehemistry was adopted to observe the expression of myeloperoxidase （MPO） positive neutrophils and Caspase-3 positive neuronal cells in the hippoeampal 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, ~br 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 ceils 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 FP! （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.