The Mechanism Of Electroacupuncture Improving Working Memory In Rats With Vascular Dementia Based On Prefrontal-hippocampal Nerve Fiber Connection

Objective:To explore whether electroacupuncture at Baihui and Shenting points could improve the working memory ability of rats with vascular dementia through enhancing the prefrontal-hippocampal nerve fiber connection.Methods:88 healthy male 8-week-old SD rats(body weight 280g±30g)were divided into sham operation group with 18 rats and operation group with 70 rats.Two-vessel occlusion(2VO)was performed to construct the model of VD rat,while the sham operation group only separated the bilateral common carotid arteries without ligation.Working memory behavior tests were used to detect whether the working memory of VD rats were damaged.Based on the results above,54 rats of the operation group were modled successfully with working memory impairment and were randomly divided into the model group,the electroacupuncture group and the non-acupoint group,18 rats in each group.The electroacupuncture group and the non-acupoint group began to intervene on the 14 th day after the operation.The electroacupuncture group took the Baihui and Shenting points,and the non-acupoint group took the right axillary non-acupoint,using a dilatational wave with a frequency of 1/20 Hz,once a day,30mins/time,for a total of 28 days.Before and after the intervention,water maze and new object recognition tests were used to detect the working memory ability of each group.BOLD-fMRI and DTI were used to observe the changes of neurological activities and prefrontal-hippocampal nerve fiber connection of each group before and after intervention,and to analyze the correlation with working memory behavioral performance.Results:1.Effects of electroacupuncture on working memory ability of VD rats: Before intervention,the average escape latency of the model group,the electroacupuncture group and the non-acupoint group were significantly increased compared with the sham group(P<0.001).There were no difference among the model group,the electroacupuncture group and the non-acupoint group(P>0.05);After intervention,the average escape latency of the electroacupuncture group was significantly decreased compared with the model group and the non-acupoint group(P<0.001).The results of the new object recognition test showed that before intervention,the preference coefficient of the model group,the electroacupuncture group and the non-acupoint group were significantly decreased compared with the sham group(P<0.005),and there were no difference among the model group,the electro-acupuncture group,and the non-acupoint group(P>0.05).After intervention,the preference coefficient of the electroacupuncture group was increased compared with the model group and the non-acupoint group(P<0.05).2.Effects of electroacupuncture on neurological activities in VD rats: The results of ReHo value showed that after intervention,the ReHo value in the prefrontal cortex and hippocampus of the model group were significantly reduced compared with the sham group(P<0.005);The ReHo value in the prefrontal cortex and hippocampus of the electroacupuncture group was significantly increased compared with the model group and the non-acupoint group(P<0.005).There were no difference of the ReHo value between the non-acupoint group and the model group(P>0.05).3.Effects of electroacupuncture on the prefrontal-hippocampal nerve fiber connection in VD rats: The results of the Prefrontal-hippocampal fiber tracking showed that before intervention,the connection of the nerve fiber from prefrontal cortex to hippocampus of the model group,the electroacupuncture group and the non-acupoint group were significantly reduced compared with the sham group(P<0.001),and there were no difference among the three groups(P>0.05);After intervention,the connection of the nerve fiber from prefrontal cortex to hippocampus of the electroacupuncture group was significantly increased compared with the model group and the non-acupoint group(P<0.001),and there were no difference between the model group and the non-acupoint group(P>0.05).4.Correlation analysis between the working memory behavioral performance and the prefrontal-hippocampal nerve fiber connection: The correlation coefficient between the preference coefficient in the new object recognition test and the nerve fiber connection was r=0.504(P<0.001);The correlation coefficient between the average escape latency in the water maze test and the nerve fiber connection was r=-0.717(P<0.001);The results above suggested that the prefrontal-hippocampal nerve fiber connection is positively correlated with the working memory ability.Conclusion:Electroacupuncture at Baihui and Shenting points could improve the working memory ability of VD rats through activating the neurological activities in the prefrontal cortex,hippocampus and enhancing the prefrontal-hippocampal nerve fiber connection.