电针对脑缺血再灌注损伤大鼠Toll样受体4/核因子κB信号通路的影响

Electroacupuncture reduces inflammatory factor expression by suppressing Toll-like receptor 4/nuclear factor-kappa B signaling in rats with cerebral ischemia-reperfusion injury

背景:炎症反应是诱发脑缺血再灌注损伤的重要因素之一。研究表明电针可有效降低缺血性脑卒中后炎症反应,改善神经功能缺损症状,但机制尚未明确。目的:观察电针对脑缺血再灌注损伤大鼠Toll样受体4/核因子κB信号通路及炎性因子表达的影响。方法:48只雄性SD大鼠随机分为假手术组、模型组和电针组,每组16只,采用大脑中动脉线栓阻断法制备脑缺血再灌注损伤大鼠模型。造模24 h后对电针组大鼠行电针干预,每天1次,每次20 min,共5 d;假手术组和模型组不做任何干预。干预5 d后根据Longa法评定各组大鼠神经功能损伤程度;TTC染色和苏木精-伊红染色分别观察大鼠脑梗死体积及脑组织病理形态,荧光定量PCR和Western blot分别检测大脑皮质中Toll样受体4、核因子κB mRNA和蛋白表达;酶联免疫法检测血清中炎性因子白细胞介素6、白细胞介素18和肿瘤坏死因子α水平。结果与结论:①与假手术组比较,模型组大鼠神经功能评分、血清白细胞介素6、白细胞介素18、肿瘤坏死因子α水平、大脑皮质Toll样受体4、核因子κB mRNA及蛋白表达水平明显升高(P<0.01);与模型组比较,电针组大鼠神经功能评分、大脑皮质Toll样受体4、核因子κB mRNA及蛋白表达,血清白细胞介素6、白细胞介素18、肿瘤坏死因子α水平明显降低(P<0.05,P<0.01);②与假手术组比较,模型组大鼠脑梗死体积明显增加(P<0.01);与模型组比较,电针组大鼠脑梗死体积减小(P<0.05);③模型组神经元排列紊乱,部分神经细胞消失,胞核固缩,结构不完整;电针组大脑皮质神经元变性及神经细胞数量丢失程度均有不同程度减轻;④结果表明,电针能明显改善脑缺血再灌注损伤模型大鼠的神经行为学,减轻脑组织损伤,有效降低血清炎性因子水平,其机制可能与抑制Toll样受体4/核因子κB信号通路有关。

BACKGROUND:Inflammation is one of the important factors that induce cerebral ischemia-reperfusion injury.Studies have shown that electroacupuncture can effectively reduce inflammation after ischemic stroke and improve the symptoms of neurological deficits,but the mechanism is not clear.OBJECTIVE:To observe the effect of electroacupuncture on Toll-like receptor 4/nuclear factor-κB in rats with cerebral ischemia-reperfusion injury.METHODS:Forty-eight male Sprague-Dawley rats were randomly divided into sham operation group,model group and electroacupuncture group,with 16 rats in each group.The rat model of cerebral ischemia-reperfusion injury was prepared by middle cerebral artery occlusion.At 24 hours after modeling,the rats in the electroacupuncture group were treated with electroacupuncture,once a day,20 minutes each time,for a total of 5 days.The sham operation group and the model group did not do any intervention.After 5 days of intervention,Longa method was used to evaluate the degree of neurological injury in rats.Triphenyl tetrazolium chloride staining and hematoxylin-eosin staining were used to measure the volume of cerebral infarction and the pathological changes of brain tissue in rats.Serum interleukin-6,interleukin-18 and tumor necrosis factor-αwere detected by ELISA.Expressions of Toll-like receptor 4 and nuclear factor-κB in the cerebral cortex at mRNA and protein levels were detected by fluorescence quantitative PCR and western blot,respectively.RESULTS AND CONCLUSION:Compared with the sham operation group,the neurological function scores,serum interleukin-6,interleukin-18,and tumor necrosis factor-αlevels,Toll-like receptor 4 and nuclear factor-κB mRNA and protein expression levels were significantly higher in the model group(P<0.01).Compared with the model group,electroacupuncture significantly reduced the neurological function scores,serum interleukin-6,interleukin-18,and tumor necrosis factor-αlevels,Toll-like receptor 4 and nuclear factor-κB mRNA and protein expression levels(P<0.05,P<0.01).Compared with the sham operation group,the volume of cerebral infarction in the model group increased significantly(P<0.01).Compared with the model group,the volume of cerebral infarction in the electroacupuncture group decreased(P<0.05).In the model group,the arrangement of neurons was disordered,some nerve cells disappeared,nuclei presented with pyknosis and incomplete structure.After electroacupuncture intervention,the degree of neuronal degeneration and neuronal loss in the cerebral cortex of rats were reduced compared with those in the model group.To conclude,electroacupuncture can significantly improve the neurobehavior of rats with cerebral ischemia-reperfusion injury,reduce brain tissue injury,and effectively reduce the level of serum inflammatory factors.The mechanism may be related to the inhibition of Toll-like receptor 4/nuclear factor-κB signaling pathway.