促红细胞生成素对发育期小鼠脑损伤后神经细胞凋亡和caspase-3表达的影响

Effects of erythropoietin on neuron apoptosis and expression of caspase-3 after excitotoxic braininjury in mice during different developmental stages

目的研究促红细胞生成素（erythropoietin，EPO）对鹅膏蕈氨酸（ibotenicacid，Ibo）致发育期小鼠兴奋性脑损伤后神经细胞凋亡和caspase-3表达的影响。方法以144只健康雌性昆明小白鼠作为实验动物，其中7日龄（p7）、21日龄（P21）和42日龄（Pd2）小鼠各48只；再将同日龄小鼠随机（随机数字法）分为假手术组（n=16）、Ibo模型组（n=16）和EPO治疗组（n=16）。采用颅内微量注射法向小鼠左侧海马注射Ibo1斗1（5峭）建立脑损伤模型。EPO治疗组小鼠海马注射Ibo后，腹腔注射5000U／（kg·d）EPO，连续3d；Ibo模型组和假手术组腹腔注射等体积生理盐水。各组小鼠在建模后3d处死，Nissl染色观察小鼠海马神经细胞凋亡病理改变；双抗体夹心ABC．ELISA法检测caspase．3含量变化；分光光度法检测caspase-3活性改变。结果光学显微镜观察结果显示，与假手术组相比，Ibo模型组小鼠海马区神经细胞发生明显变性和死亡，神经细胞数量明显减少；EPO治疗组小鼠海马区神经细胞凋亡程度较轻。Ibo模型组与假手术组相比，aaspase-3含量和活性明显升高（P〈0．05）；EPO治疗组caspase-3含量和活性的升高幅度明显低于Ibo模型组（P〈0．05）。结论Ibo致脑损伤时，脑组织caspase-3的表达增强，导致神经细胞凋亡。EPO可减轻脑损伤后神经细胞凋亡，起到脑保护的作用，其机制可能与下调caspase-3的表达有关。

Objective To investigate the effects of erythropoietin （EPO） on neuron apoptosis and expression of easpase-3 after excitotoxie brain injury induced by ibotenic acid （Ibo） in mice during different developmental stages. Methods A total of 144 healthy KM mice aged 7 d （ n = 48 ）, 21 d （ n = 48 ） and 42 d （n = 48 ） were selected, and those of the same age were randomly （random number） divided into 3 groups ： sham surgery group （ n = 16）, Ibo group （ n = 16 ） and EPO treated group （ n = 16 ）. Brain injury model was established by Ibo 1 p.1 （5 p.g） injected into left hippocampus. In EPO treated group, intra- peritoneal injection of 5000 El （kg ~ d） EPO was performed for 3 consecutive days after injection of 1 ixl Ibo into left hippocampus. Mice in sham surgery group and Ibo control group were treated with saline in the same dose instead. The pathological changes of neurons in hippoeampus were observed 3 d after modeling in each group with Nissl staining, the level and activity of caspase-3 in hippocampus were determined by ABC- ELISA and spectrophotometry. Result After modeling, degeneration and death of neurons in hippocampuswith substantially decrease in number of intact neurons were found under light microscopy in Ibo group in comparison with sham surgery group. However, compared with the Ibo group, pathological changes in EPO treated group were less serious. The level of caspase-3 in Ibo control group was significantly higher than that in sham surgery group （P 〈 0. 05 ）, and the level of caspase-3 in EPO treated group was significantly lower than that in Ibo group （P 〈 0. 05）. Conclusions The level of caspase-3 is significantly up-regulated in hippocampus of mice with Ibo-induced brain injury, leading to neuron apoptosis. EPO mitigates brain injury and plays a role of protection on brain function, suggesting the mechanism is attributed to decrease in caspase-3.