The Effect Of Electro-Acupuncture At Lianquan(CV23) On The Swallowing-Related Neurons In The Ventrolateral Medulla Of Rats

Swallowing is one of the most complex somatic reflex,which play important role in the normal life.The normal functioning of the swallowing needs the completion of the cortex,medulla,cranial nerve,peripheral nerve,muscle and so on.Among them,the integrity of the brainstem swallowing center pattern generator(CPG)was mostly important in the swallowing function.The CPG include three parts,the nucleus of solitary tract(NTS)and its surround information,the nucleus ambiguous(NA)and the ventrolateral medulla(VLM),which above the NA.The VLM was an important parts of the CPG,which have significant role in the normal swallowing activity.The present experiment mainly studied the regulation effect of the electro-acupuncture(EA)on the swallowing-related(SR)neurons of VLM,then detect the partial mechanism of the effect of EA at Lianquan(CV23)on the regulation of swallowing function.Objective:The electrophysiology and molecular biology were used to detect the effect of the EA at CV23 on the SR neurons of VLM on the physiology condition.And the Neiguan(PC6)was used as the control acupoints.After the directed damage on the VLM,the effect of the EA at CV23 for swallowing was investigated and the role of the VLM on the EA et CV23 was explored,which totally revealed partial mechanism of EA at CV23 for the treatment of dysphagia after stroke.Experiment one: The effect of EA at CV23 on the swallowing intermediate neurons in the VLM.MethodsThirty-six sprague-dawley(SD)rat were chose,no limitation with sex.The neck surgery and cranio-cerebral window were operated after anesthesia to record the myoelectric discharge of the mandibular hyoid muscle(MH)and the discharge of the VLM neurons in the medulla.Then the drinking installation fulfill with the double distill water(DDW)was used to induce the swallowing activity(SA),determining the SR intermediate neurons in the VLM.After that,EA at the Lianquan(CV23)and Neiguan(PC6)were used to observe the effect of EA on the discharge of the SR neurons in the VLM.And the histology identification was following.ResultsHistologically,there were 72 neurons that recorded the correct location of the neurons,including 60 SR neurons and 12 non-SR neurons.The EA at CV23 could increase the rats' swallowing numbers(SN)with 15.8±0.57,while the EA at PC6 was 12.22±0.59(P<0.01).AS for the response rate,81.7% neurons respond to EA at CV23 and 50% respond to PC6,which was statistically significant difference(P<0.01).The frequency of neuron discharge increased 10.30±1.99 spike/s by EA at CV23,with 50% excitability respond rate.While there was 28% excitability response rate to EA at PC6,and the frequency of neuron discharge increased 5.56±1.32 spike/s;When mention to the neurons inhibitory respond rate,there were 37.1% and 21.7% to CV23 and PC6 respectively.And the frequency of neuron discharge decrease 10.30±1.99 spike/s by EA at CV23 and 6.17±1.77 spike/s by EA at PC6 with statistically significant difference between then.Experiment two: The effect of EA at CV23 on the expression of c-fos in the VLM.MethodsTwenty-four SD rats was chose without limitation of sex.They were randomly divided into three groups: CV23 group,PC6 group and control group.After anaesthesia,the CV23 and PC6 group were subjected to EA for 20 min.The EA parameters were 2Hz and 1mA.After that,the samples were collected for immunofluorescence(IF)detection.ResultsThe number of c-fos positive cells for CV23 and PC6 groups were 20.63±2.35 and 14.13±1.78 respectively.Compared with the blank group,the expression of c-fos in CV23 and PC6 group increased significantly,while the CV23 group were significantly higher than PC6 group(P<0.01)Experiment three: The effect of the EA at CV23 on regulation SA after the destruction of the VLM.MethodsTwenty SD rats was chose without limitation of sex and randomly divided into experimental and control group.The experimental group was injected with ibotenic acid(IBO),while the control group was injected with equal amount of normal saline.At the same time,the electromyography of MH muscle was recorded.After the injection,EA at CV23 and PC6.Then,the electromyography of MH muscle was observed,comparing with the electromyography of MH muscle before lesion.The histology identification was done after the injection.ResultsThe electromyography of MH muscle was changed by EA at CV23 before the injection.After the injection of IBO,the electromyography of the MH muscle was unchanged by EA at CV23 and there was the same result as the PC6.While the MH muscle was changed by EA at CV23 and PC6 after the normal saline injection into the same location.ConclusionEA could significantly activate the SR neurons in VLM,CV23 is more obvious than the PC6.And EA at CV23 acupoint can increase the expression of c-fos in the nucleus of VLM,which was more effective than EA at PC6.After the lesion at the VLM,the EA at the CV23 has no regulating effect on the swallowing activity,which indicated that the VLM was important in regulating swallowing function by EA at CV23.Those results revealed that the EA at CV23 could regulate the neurons activity in brain stem part of SR nucleus,which is one of the main mechanisms of acupuncture treatment for dysphagia after stroke.