褪黑素通过Nrf2/HO-1信号通路减轻大鼠脑缺血再灌注损伤
Melatonin alleviates cerebral ischemia reperfusion injury in rats through Nrf2/HO-1 signaling pathway

摘要：目的 研究褪黑素对脑缺血再灌注后Nrf2/HO-1信号通路的调控作用。方法 SPF级雄性SD大鼠99只随机分为假手术组、脑缺血再灌注组、褪黑素处理组，对脑缺血再灌注组和褪黑素处理组采用线栓法制作脑缺血再灌注模型，缺血90min后拔出线栓进行再灌注，褪黑素处理组在再灌注即刻和12h后按5mg/kg体质量腹腔注射褪黑素，脑缺血再灌注组腹腔注射3.43mol/L无水乙醇生理盐水溶液；改良Garcia JH评分评估3组动物神经缺损的严重程度，Nissle染色观察24h后梗死面积，HE染色观察3组大鼠脑组织梗死灶神经元的改变，免疫组化观察3组大鼠组间HO-1、GFAP和NF200的表达情况，Western blot检测3组大鼠组间Nrf2和HO-1的表达。结果 褪黑素处理能提高脑缺血再灌注后1、3、7d神经功能评分(P<0.05)；褪黑素处理后可以增加脑缺血急性期Nrf2和HO-1的表达(P<0.05)；褪黑素处理能减少GFAP的表达(P<0.05)，增加NF200的表达。 结论 褪黑素对脑缺血再灌注损伤有保护作用，其机制可能为褪黑素激活了Nrf2/HO-1信号途径，促进抗氧化蛋白HO-1的表达；同时，褪黑素可能抑制神经胶质细胞生成胶质瘢痕，有利于神经轴突再生。
ABSTRACT: Objective To study the regulation of Nrf2/HO-1 signal pathway by melatonin after cerebral ischemia reperfusion. Methods We divided 99 SPF grade male SD rats into sham-operation group, cerebral ischemia reperfusion group and melatonin treatment group randomly. The cerebral ischemia reperfusion model was established by middle cerebral artery occlusion, Reperfusion was performed after 90min of ischemia. In the treatment group, melatonin was injected into the abdomen at 5mg/kg body weight immediately and 12 hours after perfusion. Anhydrous ethanol saline solution of 3.43mol/L was injected peritoneally in the cerebral ischemia reperfusion group. We assessed the severity of nerve defects in the three groups of animals according to the modified Garcia JH score. Nissle staining was used to observe the infarct area 24h later. HE staining was used to observe the changes of neurons in cerebral infarction. The expressions of HO-1, GFAP and NF200 in the three groups were observed by immunohistochemistry. Differences in the expressions of Nrf2 and HO-1 in the three groups were detected by Western blot. Results Melatonin treatment could improve early and late neurological function scores after cerebral ischemia reperfusion (P<0.05). Melatonin treatment increased the expressions of Nrf2 and HO-1 in the acute phase of cerebral ischemia (P<0.05). Melatonin treatment could reduce the expression of GFAP and increase the expression of NF200. Conclusion Melatonin has a protective effect on cerebral ischemia reperfusion injury, which may be related to the activation of Nrf2/HO-1 signaling pathway, thus promoting the expression of antioxidant protein HO-1. Melatonin may inhibit glial cells from forming glial scar and facilitate axonal regeneration