山奈酚对脑缺血再灌注大鼠神经元超微结构及TLR4/NF-κB的影响

Effects of kaempferol on neurons ultrastructure and TLR4/NF-κB in rats after cerebral ischemia-reperfusion

目的:观察山奈酚对脑缺血再灌注(ischemia-reperfusion,I/R)大鼠海马神经元超微结构的影响,研究其对TLR4(Tolllike receptor4,TLR4)/NF-κB(nuclear factor-κB,NF-κB)通路的作用。方法:将120只雄性SD大鼠随机分为假手术组,模型组,山奈酚低、中、高剂量组(5,10,20 mg·kg-1)和尼莫地平组。线栓法制作大鼠中动脉闭塞(middle cerebral artery occlusion,MCAO)模型,观察山奈酚对神经功能症状、脑梗死体积和HE染色后病理形态学的影响,并通过透射电镜观察海马CA1区神经元超微结构的变化,免疫组化SP法检测TLR4和NF-κBp65蛋白的表达,ELISA法检测血清中肿瘤坏死因子-α(TNF-α)和白介素1-β(IL-1β)含量。结果:与假手术组相比,模型组神经功能症状和脑梗死体积明显,病理形态学和海马CA1区神经元超微结构显示神经元损伤严重,TLR4,NF-κBp65,TNF-α和IL-1β表达增多(P<0.01)。与模型组相比,尼莫地平组和山奈酚给药组能显著改善神经功能症状、脑梗死体积、病理形态学和海马CA1区神经元超微结构,减少TLR4和NF-κBp65的表达,降低TNF-α和IL-1β的含量(P<0.01)。结论:山奈酚局灶性脑缺血再灌注损伤的神经保护作用可能是通过调节TLR4/NF-κB通路表达。

BJECTIVE To observe effects of kaempferol on hippocampal neuron ultrastructure after focal cerebral ischemia reperfusion （I/R） in rats, and investigate the drug effects on Toll-like receptor4 （TLR4） and nuclear transcription factor kB （NF-κB）. METHODS One hundred and twenty male SD rats were randomly divided into sham operation group, I/R group, low （5 mg.kg^-1 ）, middle （10 mg.kg^- 1 ） and high （20 mg.kg^-1 ） doses of kaempferol groups and nimodipine group. Focal cer- ebral ischemia in rats was established by inserting a monofilament suture into internal carotid artery and then reperfused （MCAO）. The effects of kaempferol on neurological deficit scores, infarction volume of brain and pathological changes after HE stain was detected. Changes of hippocampal neuron ultrastructure were observed by transmission electron microscopy. Ex- pression of TLR4 and NF-κBp65 was determined by immunohistochemistry. And contents of TNF-α and IL-1β were measured by ELISA kits. RESULTS Compared with sham operation group, neurological scores and infarction volume of the model group increased significantly, and pathological changes＇ and hippocampal neuron ultrastructure showed severe injury, expression of TLR4, NF-κBp65, TNF-α and IL-1β increased （P〈0. 01）. Compared with model group, nimodipine and kaempferol group could significantly improve neurological scores, infarction volume, the pathological changes after HE stain and changes of hipp- ocampal neuron ultrastructure. In addition, kaempferol could inhibit TLR4 and NF-κBp65 expression and release of TNF-a and IL-ll3 （P〈0. 01）. CONCLUSION The neuroproteetive effects of kaempferol against focal cerebral I/R injury may attribute to inhibiting expression of TLR4/NF-κB pathway.