Electroacupuncture Regulates Hippocampal CA3-CA1 In Rats With Vascular Cognitive Impairment Mechanisms Of Temporal Pattern-dependent Synaptic Plasticity In Neural Circuits

Objective:This study aims to investigate the potential mechanism of electroacupuncture"Baihui"and"Shenting"points to regulate time-pattern-dependent synaptic plasticity of hippocampal CA3-CA1 neural circuit and improve spatial learning and memory impairment in rats.To provide experimental evidence for its clinical treatment.Methods:（1）SPF healthy male SD rats were divided into sham operation group and model group.Rats in the model group were established chronic cerebral ischemia model by permanent ligation of bilateral common carotid arteries.Vascular ligation was detected by MRI and spatial learning and memory function was detected by Barnes maze.The rats were divided into 3 groups according to the random number table method,including model group,electroacupuncture group and non-hole group,with 12 rats in each group.（2）"Baihui"and"Shenting"points were selected in the electroacupuncture group,and"non-acupuncture"points were selected in the hypoflank acupuncture group for electroacupuncture intervention.Intervention parameters:density wave 1/20Hz,once a day,30min each time,intervention 5 days a week,intervention 4 weeks.The rats in other groups were grabbed and fixed under the same conditions,and no other treatment was given.（3）Four weeks after electroacupuncture intervention at"Baihui"and"Shenting"points,morris water maze was used to test the spatial learning and memory function of rats in each group after intervention.The morphology and density of dendritic spines were detected by Golgi staining.Electrophysiological patch clamp technique was used to detect the long-term enhancement induced by Theta string stimulation in hippocampal ca3-CA1 region of rats in each group,and whole-cell patch clamp technique was used to detect the time-dependent long-term enhancement of individual hippocampal neurons.Whole cell patch clamp technique was used to detect the n-methyl-D-Aspartate receptor（NMDAR）channel currents and increase curves of rats in each group.Protein western blot was used to detect the expression of NMDA receptor subtypes NMDAR-2A and NMDAR-2B,Ca MKⅡand P-CAMKⅡproteins in hippocampus of rats in each group.Results:（1）VCI rat model test:MRI results showed that the blood flow of bilateral common carotid arteries was significantly reduced and bilateral common carotid arteries were blocked in the model group;Compared with the sham operation group,the escape latency of rats in model group,electroacupuncture group and non-point group was significantly increased（P<0.05 P<0.05 P<0.05）,the contact times of target hole and the residence time of target quadrant decreased significantly（P<0.001 P<0.001）.（2）The effects of electroacupuncture at"Baihui"and"Shenting"points on spatial learning and memory in VCI rats:compared with the operation group,the escape latency of rats in model group was significantly prolonged（P<0.01）;Compared with model group,the escape latency of electroacupuncture group was significantly shortened（P<0.05）;The number of platform crossing and the residence time in the target quadrant increased significantly（P<0.05 P<0.05）.（3）Effects of electroacupuncture at"Baihui"and"Shenting"points on the morphology and density of dendritic spines in VCI rats:Golgi staining results showed that the density of dendritic spines in model group decreased significantly compared with sham group（P<0.001）,compared with the model group,the density of dendritic spines in the electroacupuncture group was significantly increased（P<0.05）.In terms of morphology,the dendritic spines in the sham operation group were complete,compact,complete and neatly arranged,while the dendritic spines in the model group and the non-acupoint group were disordered and sparsely arranged,and large areas of dendritic spines fell off and atrophied,while the number of dendritic spines in the electroacupuncture group increased.（4）The effects of electroacupuncture at baihui and Shenting points on time-pattern-dependent synaptic plasticity of hippocampal CA3-CA1 in VCI rats:The long-term enhancement of hippocampal neurons induced by Theta burst stimulation showed that the slope of excitatory postsynaptic potential in the model group was significantly lower than that in the sham group（P<0.01）,the slope of excitatory postsynaptic potential in the electroacupuncture group was significantly higher than that in the model group（P<0.001）;Long-term enhancement of single hippocampal neurons induced by pre-and post-paired stimuli showed that the amplitude of induced excitatory postsynaptic current decreased significantly in the model group compared with the sham group（P<0.001）;Compared with the model group,the amplitude of induced excitatory postsynaptic current was significantly increased in the electroacupuncture group（P<0.05）.（5）The effects of electroacupuncture at"Baihui"and"Shenting"points on the NMDAR channel currents and the increasing curve of hippocampal pyramidal neurons:Whole-cell patch clamp detection of NMDAR channel currents showed that compared with sham operation group,the ratio of NMDAR channel currents to AMPAR channel currents(I_NMDAR/I_AMPAR)in model group was significantly decreased（P<0.01）;Compared with the model group,the ratio of I_NMDAR/I_AMPAR in the electroacupuncture group was significantly higher（P<0.05）;The results of NMDAR channel current increasing curve showed that the ratio of 40,60,80,100,120,140,160,180,200μA to 20μA in model group and non-hole group was significantly decreased（P<0.001）,the ratio of different stimulation amount to20μA in electroacupuncture group was significantly increased（P<0.05 P<0.05.）.（6）The effects of electroacupuncture"Baihui"and"Shenting"on NMDAR-2A,NMDAR-2B,Ca MKⅡand p-CAMKⅡin hippocampus:Western blot results showed that compared with sham operation group,the expression of NMDAR-2A,NMDAR-2B,Ca MKⅡand p-CAMKⅡin hippocampus of model group were significantly decreased（P<0.001 P<0.001 P<0.001 P<0.001）;The expression of NMDAR-2A,NMDAR-2B,Ca MKⅡand p-CAMKⅡincreased significantly after 4 weeks of electroacupuncture at"Baihui"and"Shenting"points（P<0.01 P<0.01 P<0.05 P<0.05）.Conclusion:Our results indicate that electroacupuncture at baihui and Shenting points can increase the current of NMDA receptor channel by upregulating the phosphorylation of NMDAR-2A and NMDAR-2B subunits and Ca MKⅡ,and affect the time-pattern-dependent synaptic plasticity of clustered neurons and individual hippocampal neurons in the ca3-CA1 region.To improve spatial learning and memory disorders in VCI rats.