Ngn2调节Nrf2/HO-1对脑缺血模型大鼠脑微结构、角质细胞活性的影响

Ngn2 effects on brain microstructure and keratinocyte activity in cerebral ischemia rats via regulating Nrf2/HO-1

背景:研究显示,血红素氧化酶1(heme oxidase-1,HO-1)在脑缺血再灌注损伤中具有重要作用;核因子E2相关因子2(nuclear factor-erythroid2-related factor2,Nrf2)能减轻脑缺血再灌注损伤,其作用是通过调控下游抗氧化蛋白实现的;推测Nrf2/HO-1在脑部疾病中均有一定的调控作用。目的:探究神经源素2(neurogenin 2,Ngn2)通过调节Nrf2/HO-1对脑缺血大鼠脑微结构、角质细胞活性的影响。方法:SPF级雄性SD大鼠55只,随机取10只为健康组不进行干预;其余大鼠建立脑缺血模型,将建模成功的40只大鼠随机分为4组:其中模型组大鼠脑内注射生理盐水;Ngn2组大鼠脑内注射Ngn210 mg/kg;Nrf2/HO-1组脑内注射HO-1及Nrf2激动剂莱菔硫烷各10 mg/kg;联合调节组脑内注射Ngn2并联合Nrf2/HO-1组用药,均连续给药3 d。分数各向异性图像观察脑微结构,苏木精-伊红染色观察脑组织的病理形态,TUNEL法检测神经胶质细胞凋亡,免疫印迹和PCR分别检测Nrf2、HO-1的蛋白及mRNA表达。结果与结论:(1)与健康组比较,模型组大鼠脑组织中梗死灶周围皮质、梗死核心相对分数各向异性值表达较低(P<0.05);与模型组比较,Ngn2组及Nrf2/HO-1组上述表达升高(P<0.05);联合调节组上述表达高于Ngn2组及Nrf2/HO-1组(P<0.05);(2)模型组大鼠大量损伤神经元,细胞稀疏,排列紊乱,大量浸润;Ngn2组与Nrf2/HO-1组损伤侧神经元好转,仍见神经细胞缺失紊乱及细胞黏附;联合调节组脑组织神经细胞坏死减轻,浸润改善;(3)与健康组比较,模型组大鼠神经胶质细胞凋亡较高(P<0.05);与模型组比较,Ngn2组及Nrf2/HO-1组神经胶质细胞凋亡降低(P<0.05);联合调节组神经胶质细胞凋亡低于Ngn2组及Nrf2/HO-1组(P<0.05);(4)与健康组比较,模型组大鼠脑组织Ngn2mRNA及Nrf2、HO-1的蛋白和mRNA表达较低(P<0.05);与模型组比较,Ngn2组、Nrf2/HO-1组Ngn2 mRNA及Nrf2、HO-1的蛋白和mRNA表达升高(P<0.05);联合调节组Ngn2 mRNA及Nrf2、HO-1的蛋白和m RNA表达高于Ngn2组及Nrf2/HO-1组(P<0.05);(5)结果说明,Ngn2通过调节Nrf2/HO-1对脑缺血大鼠产生保护作用,其机制可能与改善脑微结构、角质细胞活性以及增强Nrf2、HO-1表达等具有一定相关性。

BACKGROUND:Heme oxidase-1(HO-1)plays an important role in cerebral ischemia-reperfusion injury.Nuclear factor-erythroid 2-related factor 2(Nrf2)can reduce cerebral ischemia-reperfusion injury via regulating downstream antioxidant proteins.Therefore,it is speculated that Nrf2/HO-1 has a certain regulatory role in brain diseases.OBJECTIVE:To explore the effects of Neurogenin 2(Ngn2)on brain microstructure and keratinocyte activity in cerebral ischemia rats by regulating Nrf2/HO-1.METHODS:Fifty-five SPF male Sprague-Dawley rats were selected,10 of which were randomly selected as healthy group and the remaining rats were used to establish animal models of cerebral ischemia.After modeling,40 model rats were randomly divided into 4 groups:rats in model group were intracerebrally injected with normal saline;rats in Ngn2 group were intracerebrally injected with Ngn210 mg/kg;rats in Nrf2/HO-1 group was intracerebrally injected with Ho-1 and Nrf2 agonist sulforaphane 10 mg/kg;and rats in combined group received intracerebral injection of Ngn2 combined with Nrf2/HO-110 mg/kg.Administration in each group lasted for 3 consecutive days.Fractional anisotropy imaging was used to observe the brain microstructure.Hematoxylin-eosin staining was used to observe the pathological morphology of brain tissue.TUNEL method was used to detect glial cell apoptosis.Western blot and PCR were used to detect Nrf2 and HO-1 protein and mRNA expressions,respectively.RESULTS AND CONCLUSION:(1)Compared with the healthy group,the relative fraction anisotropy values of the peri-infarct cortex and infarct core were lower in the model group(P<0.05).Compared with the model group,the relative fraction anisotropy values of peri-infa rct cortex and infarct core were increased in the Ngn2 group and Nrf2/HO-1 group(P<0.05).Compared with the Ngn2 group and Nrf2/HO-1 group,the relative fraction anisotropy values of peri-infarct cortex and infarct core were increased in the combined group(P<0.05).(2)In the model group,a large number of neurons were damaged,and the cells were sparse,disordered and infiltrated.In the Ngn2 group and Nrf2/HO-1 group,the neurons on the injured side were improved,and the loss,disorder,and adhesion of nerve cells were still observed.In the combined group,the necrosis of nerve cells was reduced and cell infiltration was improved.(3)Compared with the healthy group,the apoptosis of glial cells was higher in the model group(P<0.05).Compared with the model group,the apoptosis of glial cells was decreased in the Ngn2 group and Nrf2/HO-1 group(P<0.05).Compared with the Ngn2 group and Nrf2/HO-1 group,the apoptosis of glial cells was decreased in the combined group(P<0.05).(4)Compared with the healthy group,the expressions of Ngn2 mRNA and Nrf2 and HO-1 at protein and mRNA levels were lower in the model group(P<0.05).Compared with the model group,the expressions of Ngn2 mRNA and N rf2 and HO-1 at protein and mRNA levels were increased in the Ngn2 group and Nrf2/HO-1 group(P<0.05).Compared with the Ngn2 group and Nrf2/HO-1 group,the expressions of Ngn2 mRNA and Nrf2 and HO-1 at protein and mRNA levels were increased in the combined group(P<0.05).(5)To conclude,Ngn2 can protect rats from cerebral ischemia by regulating Nrf2/HO-1,and the mechanism may be related to improving brain microstructure,keratinocyte activity and expression of Nrf2 and HO-1.