Effect Of 5-HT_1A Of Nucleus Of Solitary Tract At Regulation Of Electroacupuncturing Fengfu And Lianquan Acupoints To Swallowing Activities

BackgroundSwallowing function is one of the most basic and important physiological activity of the mammals including human and its main role is to put the food from the throat to the stomach.If any trouble happens in swallowing process,the dysphagia will happen,which is one of the common complications of cerebral apoplexy and brings serious damage to human health.The oropharyngeal phase initiation of swallowing of most species is accompanied by the co ntraction of mylohyoid muscle,so the mylohyoid muscle is usually considered as the first muscle that has been activated in swallowing process.All of the inputs of peripheral and the central nervous above medulla oblongata involved in swallowing activity terminate in nucleus tractus solitarii.The neurons of nucleus of solitary tract are the initiating neurons of swallowing neuron network,which involved in the initiation,formation and time control of the continuity and rhythm of swallowing activity.There are ample serotonin?5-HT?in the nucleus of solitary tract,and the presence of serotonin in nerve terminals and fibers has been particularly well-documented while the existence of several putative neurotransmitters within the NTS has been well demonstrated.Previous work has shown that 5-HT and its subtypes such as 5-HT_1A to exert a powerful excitatory or inhibited effect on both reflex and automatic swallowing and implicated the NTS as the principal locus of action.Our previous experiments had verified acupuncturing 'Fengfu' and'Lianquan' points could induce the electromyography changes of mylohyoid,and activate the swallowing relevant neurons in the nucleus of solitary tract.This research will further discuss the action mechanism of acupuncturing to NTS swallowing center from the neuropharmacology perspective.ObjectiveTo observe the influence of acupuncturing on 5-HT_1A in the NTS and the changes of mylohyoid discharge evoked by acupuncture before and after microinjection of 5-HT_1A antagonist into the NTS,and to explore the mechanism of acupuncturing to NTS swallowing neuron through the neuropharmacology perspective.Methods1.30 SD rats Rats were randomly divided into blank group,sham operated group and acupuncture group.After anesthetized by chloral hydrate,the NTS 5-HT_1A expression of the blank group rats was observed by immunohistochemical methods.The sham operated group and the acupuncture group were given neck surgery operation after anesthesia,The acupuncture group rats were given electro-acupuncture Fengfu?DU16?,Lianquan?RN23?points 20 minutes,and observed the number of mylohyoid muscle discharge,while the model group was given no acupuncture.Both sham operated group and experimental group were taken immunohistochemical methods for 5-HT_1A positive expression in the end.2.40 SD rats were randomly divided into antagonist 1 ?L group,0.1 ? L group and physiological saline 1 ?L group,0.1 ?L group,10 rats each group.Neck surgery was performed after anesthesia as same as the experiment one,placed the EMG recording electrode.Exposed all rats obex of medullary,the Fengfu?DU16?and Lianquan?RN23?points were given electro-acupuncture for 1 minutes and then injected by the syringe pump,electro-acupuncturing was given again after 1 minutes' injection.The antagonist groups were given 1 ?L and 0.1 ?L 5-HT_1AR antagonist WAY-100635 while the normal saline groups with 1 ? L and 0.1 ? L 0.9%normal saline.The EMG frequency changes were recorded through the whole process.After the end of the experiment,identified the medullary by histological method,and data had been abandoned if injection parts were inaccurate.Results1.This study showed that the electro-acupuncture of Fengfu and Lianquan points could induce the swallowing activity of rats.2.The NTS 5-HT_1A positive expression of the acupuncture group was highest,and there were significant differences compared with blank group and sham operated group?P<0.05?.3.This study showed that the discharge of mylohyoid of the antagonist group which injected 1 ? L WAY-100635 into the NTS after injection was significantly decreased comparing with before injection?P<0.05?.There are significant differences of the discharge between the antagonist group and each other three groups?P<0.05?.ConclusionThe results suggested that electroacupuncture DU16 and RN23 could induce the swallowing activity and 5-HT_1AR in the NTS played a role involved in acupuncture regulating swallowing function.