| Objective:Through injecting the complete Freund’s adjuvant(CFA)to establish the model of chronic inflammatory pain in left hind paw of rats.Observing the Mechanical pain threshold(MPWTs)、emotional pain behavior and the changes of synchronous electrical physiological characteristics in the primary somatosensory cortex(SI),to explore the regulation of EA with the pain sensory、pain emotional behavior and the synchronous electrical physiological characteristics in rats SI region.Methods:Healthy adult male Sprague-Dawley rats were randomly divided into five groups,including the control group,model group,the model+electric acupuncture(EA)group,the ACC lesiongroup and the ACC lesion+EA group.The chronic inflammatory pain model was established by injecting 50 ul CFA into left hindpaw in rats.The model+EA group and ACC lesion+EA group were applied to bilateral “Housanli”(ST 36)from day 2 to day 14 every other day with 2/100 Hz.The ACC lesion group and ACC lesion+EA group were implanted in ACC region by two stainless steel lesion electrodes,and destroyed by a 1 m A(the 30s)direct current.To detect the mechanical pain threshold of rat in the day before CFA injection,and the day 2h、26h、16 after CFA injection.The rats in each group were conditioned twice training and then to observe the changes in the pain emotional behavior of rats in the experiment of conditioned place avoidance(CPA)and O maze experiment.The microelectrode array was placed in the SI brain region of rats and the synchronous recording of multiple channels in the body was observed,and the changes of the neural oscillations in the SI brain region were observed under the awake state.Results(一)Detection of painful sensory.(1)The paw withdrawal thresholds(PWTs)in left hind paw of rats showed no significant difference before injected by CFA.(2)26 hours after the injection of CFA and compared with the control group,there was a significant decrease in the other four groups(p < 0.01).(3)16 days after the injection of CFA and compared with the control group,the PWTs in model group and ACC lession group decreased significantly(p < 0.05).(4)Compared with the model+EA group,the PWTs of 16 d after CFA injection in this group was significantly increased than 26h(p<0.01).And the PWTs of 16 d after CFA injection in the ACC lesion+EA group was significantly higher than that after 26h(p<0.05).Shrinkage sufficient times in rats left foot show that:(1)2h、26 h after CFA injection comparing with control group,the rest of the four groups were significantly higher(p < 0.01).(2)16 d after CFA injection,compared with control group,the rest of the four groups were still increased significantly(p<0.01);Compared with the model group,model+EA group decreased significantly(p<0.01).Compared with model+EA group,there was no significant difference in ACC lession+EA group.Compared with ACC lession group,ACC lession+EA group showed a significant decrease(p<0.01).(二)Detection of pain emotional behavior.(1)The experimental results showed that there was no significant difference between the five groups of rats in the condition box and the non-conditional box before injected by CFA.(2)2 days after CFA injection,compared with control group,the CPA score in model and model+EA group have increased significantly(p< 0.05),compared with model group,the ACC lesion group and the ACC lesion +EA group showed a significant decreased(p<0.05).(2)9 days after CFA injection,compared with control group,the CPA score in model and model+EA group have increased significantly(p<0.05);compared with model group,the ACC lesion group and the ACC lesion +EA group still showed a significant decreased(p< 0.05);Compared with model+EA group,the ACC lesion +EA group showed a significant decreased(p<0.01).(3)15 days after CFA injection,compared with control group,model group still has increased significantly(p<0.05),but model+EA group had no significant;Compared with the model group,the ACC lesion group have decreased significantly(p<0.01).Compared with the model+EA group,the ACC lesion+EA group had no significant.In the O maze test,the degree of anxiety was compared by observing how manytimes the rats entering the open arm on the 16 th day after CFA injection.Compared with the control group,the timesin model group,ACC lesion group and ACC lesion+EA group was significantly reduced(p<0.01).Compared with the model group,the times in the model+EA group increased significantly(p<0.05).(三)The results of LFPs signal in the SI brain region of rats showed that:(1)Different frequency bands in the SI brain region of the model group were changed at different time points.Delta compared with the pre-model establishment,the delta frequency PSD in the 9d and 15 d after CFA injection increased significantly(p<0.01).Compared with the 2d after CFA injection,the PSD of the delta band was significantly increased in 9、15 days after CFA injection(p<0.05).Theta band: Compared with the pre-model establishment,the theta band PSD in the 2 days after CFA injection increased significantly(p<0.05);.Compared with 2 days after CFA injection,the PSD of theta band was significantly decreased in 9、15 days after CFA injection(p<0.05).alpha、beta、gamma band:Compared with the pre-mold and 2 days after CFA injection,the PSD of the three bands was significantly decreased in 9、15 days after CFA injection(p<0.05).(2)In the model+EA group,the delta band in the SI brain region at different time points was changed:Compared with the pre-model establishment,the delta band PSD significantly increased in the 15 days after CFA injection(p<0.01).Compared with 2 days after CFA injection,the PSD of the delta band increased significantly in 9、15 days after CFA injection(p<0.01).Theta band:Compared with the pre-model establishment,the theta band PSD significantly increased in 2 days after CFA injection(p<0.01).Compared with 2 days after CFA injection,the PSD of the theta band decreased significantly in 15 days after CFA injection(p<0.01).Gamma band: Compared with 2 days after CFA injection,the PSD of the gamma band decreased significantly in 9、15 days after CFA injection(p<0.05).In addition,alpha and beta band have no significant change at various time points.(3)The changes of the SI brain region at different time.There was no significant difference in the PSD of each band before injecting CFA.Alpha band: compared with control group,the PSD of the alpha band in model+EA group decreased significantly at 2 days after CFA injection(p<0.01),and the PSD of model group was significantly decreased at 9、15 days after CFA injection(p<0.05).Compared with the model group,alpha band PSD of model+EA group was significantly increased at 9、15 days after CFA injection(p< 0.05),and there was no significant difference with control group.Beta band:Compared with control group,the beta band PSD of the model group decreased significantly at 2、9、15 days after CFA injection(p<0.01),and the model+EA group decreased significantly at 2、9 days after CFA injection(p<0.01).Compared with the model group,the beta band PSD of the model+EA group increased significantly at 9、15 days after CFA injection(p<0.01).Conclusion:(1)Electroacupuncture intervention can effectively relieve the lefe hind paw mechanical pain thresholdinrats induced by CFA and produceanalgesic effect.The analgesic effect of electroacupuncture is not directly related to ACC regulation(2)Electroacupuncture intervention can effectively reduce the avoidance behavior of CFA rats,and relieve the pain and anxiety behaviors in rats,and play an inportant role in regulating the behavior.(3)Lesions of rats’ bilateral ACC could inhibit the pain behavior.(4)The intervention of EA for pain emotion may partially through the regulation of the ACC.(5)the inflammatory pain induced by the CFA may increase the delta、theta band oscillatory activity in SI rats brain regions and decrease the oscillatory activity of alpha、beta and gamma band.(6)EA intervention may achieve analgesic effect by inhibiting the oscillation activity of alpha and beta band. |
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