| Hirschsprung's disease(HD) is a congenital enteric nervous systemdisorders,its pathogenesis is not yet clear．At present,many considered to be avariety of genetic and environmental factors effect the results of coregulation．Incidence rate of 1/5000,with male more common,male:female was4:1．In recent years,the incidence of HD seems to be an upward trend in．Themain pathological changes of colonic lesions in paragraph absence of ganglioncells,sustained spastic colon disease,spasm and no peristalsis,accompanied bydistended proximal colon filled with massive feces,reductionmegacolon．Newborns showed meconium discharge delay,obstruction and othersymptoms,Infants and adults,manifested as severe constipation,bloating,andenterocolitis,low intestinal obstruction,serious impact on children's quality oflife and even life-threatening. Studies have shown that,HD children with severeintestinal motor dysfunction closely related the distribution,number and functionof the．The ICC is widely distributed in the digestive tract,is the gastrointestinal pacemaker cells in slow-wave activity and its basic electrical rhythm of the mainmode of transmission cells,and participated in the gastrointestinal tract neuralinformation transmission．This study was prepared by megacolon of the neonatalrat,using the specific ICC marker c-kit polyclonal antibody immunofluorescencestaining of ICC in megacolon model of the narrow segment,the expansionsegment and the transitional segment had a more detailed observation,to explorethe role of ICC in HD,the study of HD bowel movement dysfunction and toprovide experimental basis for treatment．Thus preparation of neonatal rat as theexperimental animal model for Hirschsprung's disease in the future further indepthstudy of HD and its related complications cause pathophysiologicalmechanisms,course and treatment of the evolution of such characteristics andlaid the experimental foundation．ObjectiObjective To establish megacolon model of the neonatal rat by chemicalablation of enteric plexus in the neonatal rat．by general observation andhistopathology,NSE and S-100 protein immunohistochemical identified successof model,c-kit immunofluorescence detected the narrow segment,the expansionsegment and the transitional segment of megacolon model of the neonatal rat ofICC the changes in distribution．Explore the role of ICC in the pathogenesis ofHD,in order to explore widly,safe,effective,non-invasive new method oftreatment to lay an experimental basis．Method1.Ninety neonatal rats,6～7days old,were randomly divided into normalgroup,experimental group and control group．All animals were operated uponunder Ether anesthesia．In experimental group,0．1% Benzalkonium chloride(BAC) solution was applied to the descending colon for 15 minutes to set up thisanimal model,0．9% normal saline was applied using the same method in control group．In normal group received no treatment．2．At an interval of 1week,3weeks,5weeks,6weeks and 7weeks after BACtreatment,each group randomly selected two neonatal were sacrificed,generalobservation and histopathology were performed．The expression of S-100 proteinand neuron-specific enolase(NSE)was detected with immunohistochemistry．3．The distribution and expression of c-kit in the narrow segment,theexpansion segment and the transitional segment of ICC was detected withimmunofluorescence．Results1．1~3week after BAC treatment,the experimental group and control groupof the general observation no significant change,4~6week after BAC treatment,some rats had abdominal distention,defecation decrease,fecal particles becomesmaller,Autopsy revealed a narrowed segment at the site of BAC treatment．7week after BAC treatment,the rats had abdominal distention,defecationdecrease,spirit flagging,emaciation,fecal pellets significantly larger and drierthan the control group and the normal group．Autopsy revealed a narrowedsegment at the site of BAC treatment,spasm and no peristalsis,accompanied bydistended proximal colon filled with massive feces．The control group and thenormal group no significant changes．2．1week,3weeks,5weeks and 6weeks after BAC treatment,the results ofhistopathology showed gradually reduction of ganglion cells in the myenteric andsubmucous plexuses decreased．7 week after BAC treatment,ganglion cells in themyenteric and submucous plexuses completely disappeared,no scar formationand inflammatory cell infiltration．The control group and the normal groupshowed normal ganglion cells in myenteric and submucoous plexuses．3．1week,3weeks,5weeks and 6weeks after BAC treatment,the expression of S-100 protein and NSE decreased in ganglion cells of myenteric andsubmucous plexuses,7week after BAC treatment,the ganglion cells of myentericand submucous plexuses completely disappeared．The control group and thenormal group no significant changes in expression．4．The distribution of ICC was detected with immunofluorescence indifferent segments．ICC were mainly distributed in submucosal plexus andmyenteric plexus of the descending colon．ICC were distributed continuouslybetween the circular and the longitudinal muscle layers and formed a network．Inthe narrow segments of megacolon model of the neonatal rat,compared with thecontrol group,the transitional segments and the expansion segments,ICC weredecreased obviously in narrow segments (P<0．01)．The ICC network weredisappeared,and the morphousmay of the residual ICC were abnormal．In thetransitional segments,ICC were reduced than the expansion segments and thecontrol group (P<0．05)．The configuration were closed to normal,but ICC didnot form a normal network．There were no difference of the distribution of ICC inthe expansion segments and the control group (P>0．05)．Conclusion1．Neonatal rats,6～7days old can be successfully established megacolonmodel of the neonatal rat by 0．1％BAC．The model have similar pathologicalfeatures with HD；2．The number and function of ICC is closely related to the occurrence anddevelopment of HD；3．NSE,S-100 protein can be used as diagnostic and differential specificindicators of HD；4．The number,morphology and distribution of ICC were different indifferent segments of megacolon model of the neonatal rat．In the narrow segment,the ICC is absence and gets blunting,decreased or disappeared footprocess,and the ICC network were disappeared．The abnormal distribution,morphousmay and number be part of the cause to the occurrence and developmentof HD．...
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