促红细胞生成素对低出生体质量新生大鼠缺氧缺血后脑神经细胞凋亡的影响

Effects of erythropoietin on apoptosis of brain nerve cells in neonatal rats with low birth weight after hypoxia-ischemia

目的探究促红细胞生成素(Erythropoietin,EPO)对低出生体质量(low birth weight,LBW)新生大鼠缺氧缺血后脑神经细胞凋亡的影响。方法2019年1—8月,选取自广东省医学实验动物中心购买的80只LBW新生大鼠以随机数字表法分为空白对照组、模型组、低剂量EPO组、高剂量EPO组,每组各20只;除空白对照组外,各组大鼠均采用结扎左侧颈总动脉并吸入80 m L/L氧气2 h制作为新生大鼠制成缺氧缺血性脑损伤(hypoxic ischemic brain damage,HIBD)动物模型;低剂量EPO组和高剂量EPO组于造模前、造模后7 d连续腹腔注射EPO(2500 IU·kg^(-1)·d^(-1)和5000 IU·kg^(-1)·d^(-1)),空白对照组和模型组腹腔注射等量的生理盐水;完成给药后24 h处死大鼠,使用HE染色法检测大鼠大脑皮层改变情况;使用TUNEL法检测大鼠神经细胞凋亡情况;使用蛋白质印迹法检测半胱氨酸天冬氨酸蛋白酶-3(Caspase-3)、半胱氨酸天冬氨酸蛋白酶-9(Caspase-9)、B淋巴细胞瘤-2(Bcl-2)、Bcl-2相关X(Bax)蛋白表达情况;使用流式细胞仪检测大鼠脑神经细胞凋亡情况。结果HE染色结果显示,空白对照组大鼠大脑皮层细胞密集、排列有序,层次清晰、分明;模型组大鼠大脑皮层细胞明显肿胀坏死、空化、间隙增宽;低剂量EPO组大鼠大脑皮层细胞轻度水肿、排列较为稀疏;高剂量EPO组大鼠大脑皮层洗白间隙增宽不明显、细胞层次较为分明、有序;TUNEL法结果显示,空白对照组、模型组、低剂量EPO组、高剂量EPO组大鼠神经细胞凋亡率分别为(10.21±2.00)%、(65.85±10.48)%、(40.32±5.22)%、(20.79±2.33)%,相比空白对照组,模型组神经细胞凋亡率、Bax、Caspase-3、Caspase-9蛋白相对表达量显著升高,Bcl-2蛋白相对表达量显著降低(P<0.05);相比模型组使用EPO处理各组神经细胞凋亡率、Bax、Caspase-3、Caspase-9蛋白相对表达量显著降低,且高剂量EPO组低于低剂量EPO组(P<0.05),Bcl-2蛋白相对表达量显著升高,且高剂量EPO组高于低剂量EPO组(P<0.05)。结论EPO可以通过抑制凋亡蛋白的表达并促进抑凋亡蛋白的表达,保护LBW新生大鼠缺氧缺血后脑神经细胞。

Objective To explore the effects of erythropoietin(EPO)on apoptosis of brain nerve cells in neonatal rats with low birth weight(LBW)after hypoxia-ischemia.Methods According to random grouping method,80 neonatal rats with LBW purchased from Guangdong Medical Laboratory Animal Center in January 2019 to January 2019 were collected and assigned into blank control group,model group,low-dose EPO group and high-dose EPO group,20 cases in each group.Except blank control group,left common carotid artery ligation and inhalation of 80 mL/Loxygen(2 h)were conducted to prepare neonatal rats of hypoxic ischemic brain damage(HIBD)models in the other group.Before and at 7 d after modeling,low-dose and high-dose EPO groups were given continuous intraperitoneal injection of EPO(2500 IU·kg^(-1)·d^(-1),5000 IU·kg^(-1)·d^(-1)),while blank control group and model group were intraperitoneally injected with the same volume of normal saline.At 24 h after administration,rats were sacrificed.The cerebral cortex changes were detected by HE staining.The apoptosis of nerve cells was detected by TUNEL.The expressions of cysteine proteinase-3(Caspase-3),cysteine proteinase-9(Caspase-9),B-cell lymphoma-2(Bel-2)and Bcl-2 associated X protein(Bax)were detected by Western blotting.The apoptosis of brain nerve cells was detected by flow cytometry.Results HE staining results showed that cerebral cortex cells were dense and well-arranged in blank control group,with clear and distinct nuance.The cerebral cortex cells in model group showed significant swelling,necrosis and cavitation,gap was widened.The cerebral cortex cells in low-dose EPO group showed mild edema.And their arrangement was relatively sparse.The gap whitening of cerebral cortex was not significant in high-dose EPO group.And cell nuance was relatively distinct and ordered.TUNEL results showed apoptosis rates of brain nerve cells in blank control group,model group,low-dose EPO group and high-dose EPO group were(10.21±2.00)%,(65.85±10.48)%,(40.32±5.22)%and(20.79±2.33)%,respectively.Compared with blank control group,apoptosis rate of nerve cells,relative expression levels of Bax,Caspase-3 and Caspase-9 were significantly increased in model group,while relative expression level of Bcl-2 was significantly decreased(P<0.05).Compared with model group,apoptosis rate of nerve cells,relative expression levels of Bax,Caspase-3 and Caspase-9 were significantly decreased in all groups treated with EPO.The above indexes in high-dose EPO group were lower than those in low-dose EPO group(P<0.05).The relative expression level of Bcl-2 was significantly increased.And the above index in high-dose EPO group was higher than that in low-dose EPO group(P<0.05).Conclusion EPO can protect brain nerve cells of LBW neonatal rats after hypoxia-ischemia by inhibiting expression of apoptosis proteins and promoting expression of anti-apoptosis proteins.