电针神庭、百会穴通过ARC/GluR2/NMDAR2B调节海马突触可塑性改善MCAO/R大鼠学习记忆的机制研究

Electroacupuncture at Shenting and Baihui Improves Learning Memory through ARC/GluR2/NMDAR2B Modulation of Hippocampal Synaptic Plasticity in MCAO/R Rats

目的观察电针神庭、百会穴对大脑中动脉闭塞再灌注(MCAO/R)大鼠学习记忆功能改善的作用机制。方法线栓法制备MCAO/R大鼠模型。24只雄性SD大鼠随机分为模型组(n=6)、电针组(n=6)、非穴组(n=6)和假手术组(n=6)。电针组大鼠选取百会、神庭穴,非穴组选取双侧胁下非经非穴,共电针7 d。ZeaLonga评分法对各组大鼠进行神经功能缺损评分,新物体识别评估大鼠的学习记忆能力,小动物磁共振T2WI系列扫描梗死面积,HE染色观察缺血侧海马病理形态,波谱(1HMRS)比较各组海马区N-乙酰天冬氨酸(NAA)、肌酸(Cr)和谷氨酸(Glu)代谢物含量,Western blotting检测缺血侧海马ARC/GluR2/NMDAR2B的表达情况。结果干预7 d后,与模型组及非穴组比较,电针组大鼠神经功能缺损评分显著降低(P<0.05),电针组大鼠新物体识别指数较模型及非穴组升高(P<0.05)。磁共振T2WI显示电针组的梗死面积较模型组、非穴组明显减小(P<0.05),波谱显示电针组较模型和非穴组海马区NAA/Cr比值明显增高(P<0.001),GLU/Cr降低(P<0.01)。Western blotting结果表明电针组大鼠缺血侧海马中NMDAR2B含量明显低于模型组和非穴组(P<0.01),ARC及GluR2含量高于模型及非穴组(P<0.05)。结论电针神庭、百会穴能够改善MCAO/R大鼠的神经缺损情况,提高学习记忆能力,降低缺血侧梗死面积,改善病理形态,提高神经元兴奋性,降低膜后谷氨酸累积,其机制可能与促进MCAO/R大鼠海马区ARC、GluR2,抑制NMDAR2B的表达,进而改善卒中后海马突触可塑性损伤有关。

Objective:To explore the mechanism of action of electroacupuncture at Shenting and Baihui points on the improvement of learning memory function in middle cerebral artery occlusion/reperfusion(MCAO/R)rats.Methods:The MCAO/R rat model was prepared by the thread bolus method.A total of 24 male SD rats were ran⁃domly divided into model group(n=6),electroacupuncture group(n=6),non-acupuncture point group(n=6)and sham operation group(n=6).The rats in the electroacupuncture group were selected from the Baihui and Shenting points,and the rats in the non-acupuncture group were selected from the bilateral non-meridian and non-acupunc⁃ture points under the locus coeruleus,and electroacupuncture was performed for a total of 7 days.Zea-Longa scor⁃ing method was used to score the neurological deficits of the rats in the various groups,to assess the learning and memory ability of the rats by new object recognition,to scan the infarct area of the rats by the small-animal mag⁃netic resonance T2WI series,to observe the pathologic patterns of the hippocampus on the ischemic side by HE staining,and to compare the hippocampus in the various groups by wave spectra(1HMRS).N-acetylaspartate(NAA),creatine(Cr)and glutamate(Glu)metabolite contents in the area,and Western blotting was used to detect the expression of ARC/GluR2/NMDAR2B in the hippocampus on the ischemic side.Results:After 7 days of inter⁃vention,compared with the model and non-acupuncture groups,the neurological deficit scores of rats in the electroacupuncture group were significantly reduced(P<0.05),and the new object recognition indices of rats in the electroacupuncture group were elevated compared with those of the model and non-acupuncture groups(P<0.05).Magnetic resonance T2WI showed that the infarct area in the electroacupuncture group was significantly reduced compared with the model and non-cavity groups(P<0.05).Wave spectra showed that the NAA/Cr ratio in the hip⁃pocampal area of the electroacupuncture group was significantly higher compared with that of the model and noncavity groups(P<0.001),and GLU/Cr was lower(P<0.01).Western blotting results showed that the content of NMDAR2B in the hippocampus on the ischemic side of the rats in the electroacupuncture group was significantly lower than those in the model and non-acupuncture groups(P<0.01),and the content of ARC and GluR2 was higher than those in the model and non-acupuncture groups(P<0.05).Conclusion:Electroacupuncture at Shent⁃ing and Baihui points can improve neurological deficits,improve learning and memory ability,reduce the infarct ar⁃ea on the ischemic side,improve pathological morphology,increase neuronal excitability and decrease the accumu⁃lation of glutamate in the post-membrane area in MCAO/R rats.The mechanism may be related to the promotion of ARC and GluR2 in the hippocampus of MCAO/R rats,inhibition of the expression of NMDAR2B,which may im⁃prove synaptic plasticity damage in the hippocampus after stroke.