巴豆生物碱通过ERK1/2通路对脑缺血再灌注大鼠海马神经元损伤及自噬的影响

目的 探讨巴豆生物碱(Croton alkaloids,CA)通过细胞外调节蛋白激酶1/2(Extracellular signal regulated kinase1/2,ERK1/2)通路对脑缺血再灌注大鼠海马神经元损伤及自噬的影响。方法 50只大鼠建立大脑中动脉闭塞(Middle cerebral artery occlusion,MCAO)再灌注模型,造模成功大鼠(48只),并随机分为模型组(12只)、CA低剂量组(12只)、CA中剂量组(12只)和CA高剂量组(12只),其余10只为对照组; CA低、中和高剂量组分别注射0.6、1.2、2.4 mg/kg的CA注射液,连续注射7 d; 对照组及模型组给予等量生理盐水注射; 应用神经功能评分法评定大鼠神经功能缺损和改善情况; 苏木精-伊红染色法(Hematoxylin eosin staining,HE)检测大鼠脑组织海马神经元的形态及数量; 原位末端转移酶标记法(Terminal uridine nick end labeling,TUNEL)检测大鼠脑组织细胞凋亡; 实时荧光定量聚合酶链反应(Real time quantitative PCR,RT-qPCR)和免疫印迹法(Western blot)检测各组大鼠海马ERK1/2、哺乳动物同源蛋白(Mammalian homologous protein,Beclin-1)、微管相关蛋白1轻链3(Microtubule-associated protein 1 light chain 3,LC3-Ⅱ)mRNA和蛋白表达水平。结果 与模型组比较,CA低、中、高剂量组神经功能评分、p-ERK1/2蛋白表达水平提高,神经细胞凋亡率、Beclin-1,LC3-Ⅱ mRNA和蛋白表达水平下降(P<0.05); 与CA低剂量组比较,CA中、高剂量组神经功能评分、p-ERK1/2蛋白表达水平提高,神经细胞凋亡率、Beclin-1,LC3-Ⅱ mRNA和蛋白表达水平下降(P<0.05); 与CA中剂量组比较,CA高剂量组神经功能评分、p-ERK1/2蛋白表达水平提高,神经细胞凋亡率、Beclin-1,LC3-Ⅱ mRNA和蛋白表达水平下降(P<0.05)。结论 CA可降低MCAO大鼠神经细胞凋亡率,在一定程度上修复MCAO大鼠神经功能,发挥神经保护作用,其机制可能与激活ERK1/2信号通路有关。

Effects of Croton alkaloids on neuronal injury and autophagy in hippocampus of rats with cerebral ischemia-reperfusion through ERK1/2 pathway

Objective To investigate the effects of Croton alkaloids(CA)on neuronal injury and autophagy in hippocampus of rats with cerebral ischemia-reperfusion through ERK1/2 pathway.Methods Cerebral ischemia-reperfusion(MCAO)model was established in 50 rats. 48 successful rats were randomly divided into model group(12 rats), CA low dose group(12 rats), CA medium dose group(12 rats)and CA high dose group(12 rats), and the other 10 rats were the control group. CA low dose group, CA medium dose group and Ca high dose group were injected with Ca injection of 0.6, 1.2 and 2.4 mg/kg, continuous injection for 7 days. The control group were given same amount of saline. The neurological deficit and improvement of rats were evaluated; HE staining was used to detect the morphology and number of neurons in hippocampus of rat brain; TUNEL method was used to detect apoptosis in rat brain tissue; RT qPCR and Western blot were usd to measure mRNA and protein expressions of ERK1/2, beclin-1 and LC3-Ⅱ in hippocampus.Results Compared with control group, the Garcia JH score, the expression of p-ERK1/2 protein in the low-dose CA Group, the medium dose CA Group and the high-dose CA group increased, and the apoptosis rate of nerve cells, the expression of beclin-1, LC3-Ⅱ mRNA and protein decreased(P<0.05). Compared with the low dose group, the Garcia JH score, p-ERK 1/2 protein expression level of Neurology in the medium dose group and high dose group were increased, and the apoptosis rate of nerve cells, the expression levels of beclin-1, LC3-Ⅱ mRNA and protein were decreased(P<0.05). Compared with the middle dose group of Ca, the Garcia JH score, p-ERK 1/2 protein expression level of Neurology in the high dose group of Ca increased, and the apoptosis rate of nerve cells, beclin-1, LC3-Ⅱ mRNA and protein expression level decreased(P<0.05).Conclusion CA could reduce the apoptosis rate of nerve cells in MCAO rats, repair the nerve function of MCAO rats to a certain extent, and play a neuroprotective effect, which might be related to the activation of the ERK1/2 signaling pathway.