| Background:Irritable bowel syndrome(IBS) is a common functional bowel disease.The etiology and pathogenesis are incompletely understood.Its pathophysiological basis is altered gastrointestinal motility and visceral hypersensitivity,usually accompanied with psychiatric disorder.Monoamine neurotransmitters in enteric nervous system,including 5-hydroxytrypatmine (5-HT) and norepinephrine(NE),play an important role in gastrointestinal sensation,motility and secretion.Abnormalities of serotonin system and sympathetic nervous system are related to the pathophysiology of IBS.An gut-brain interaction animal model of IBS,also called Chronic & Acute stress model(CAS),has been proved well repetitive.Major characteristics of IBS,such as altered colon motility,visceral hypersensitivity,and psychiatric disorder are existed in this model.We used CAS model to study the following plans on the basis of the former study about 5-HT and NE in the IBS rat model.The whole study includes three parts:Aims:1.Detecting c-fos contents in the colon,cornu dorsale,hippocampus and frontal]obe of rats,to evaluate the CAS model further.2.Perfecting and further investigating the changes and possible role of 5-HT system and NE system in IBS.3.Observing the overall view of protein of colon of brain-gut interaction IBS model utilizing proteomics,so as to study whether there are abnormalities in protein levels in IBS.Materials and Methods:Health male adult Wistar rats were selected and divided into four groups: control,acute stress(AS),chronic stress(CS) and Chronic & Acute stress(CAS).The consumption of sucrose solutions,the fecal pellets, frequency of abdominal muscle contraction by colorectal balloon distention (CRD) of rats after different stresses were observed to reevaluate colon motility,visceral sensation and behavior changes of model.Immunohistochemical method was used to determine enterochromaffin cells and toludine blue staining was used to measure mast cells in colon of rats. Double immunohistochemical method was used to detect TH and the degree of its activation.The change of TH protein level in the colon of rats was examed by Western Blot.The changes of TH mRNA and c-fos mRNA expression in the distal colon of rats and the colon mucosa of human were detected by Real time RT-PCR. MALDI-TOF-MS was used to measure the protein fingerprint in colon of rats.Results:1.Compared with the control,the levels of Fos protein in frontal lobe, hippocampus and cornu dorsale of CAS rat were significantly elevated (P=0.026,0.002,0.013),but its level in colon was slightly increased(P=0.205); and similar results were seen in those of CS rats.Fos protein contents in frontal lobe,hippocampus,cornu dorsale and colon of AS were no different compared with the control(P＞0.05).2.CAS led to increased amount of EC,MC and percentage of activated MC (activated MC%)(P＜0.05).The amount of MC and EC in the colon of AS was no different from that of control group(P＞0.05),but AS resulted in increased activated MC%(P＞0.05).The amount of EC,MC and activated MC%increased significantly in the colon of CS(P＜0.05).3.The content of NE in the colon of CAS rats was higher than that of the control(P＞0.05),and TH protein and TH mRNA increased without statistical significance compared to those of the control(P=0.590,0.363).Compared to the control group,the content of NE in the colon of AS was no different,and TH protein and TH mRNA had the increased tendency(P＞0.05).The NE level in the colon of CS rats had decreased tendency,and TH protein and TH mRNA were no different(P＞0.05).4.The correlation coefficient between colon 5-HT systems and TH was no statistically significant(P＞0.05).5.TH and c-fos mRNA levels in the colon mucosa of diarrhea-predominant IBS(IBS-D) patients were slightly higher than those of normal control (P=0.466,0.110).TH mRNA in the colon mucosa of constipation-predominant IBS(IBS-C) patients was lower than that of IBS-D patients,but no different from that of normal control(p＞0.05).6.As far as protein/peptide quality different peak was concerned,CAS rats have 18 different peaks compared with the control rats,10 peaks compared with CS rats,and 1 peak compared with AS rats.The protein level in the colon of CAS rats was highest.The different proteins among CAS,CS,AS and the control groups were repeated.7.Compared with the control group,the number of fecal pellets and frequency of abdominal contraction induced by CRD increased,and the amount of weight gain and consumption of sucrose solutions decreased in CAS(P＜0.05).Conclusions:1.CAS led to significantly increased Fos protein in parts of brain-gut axis(especially cornu dorsale and hippocampus),while AS couldn't activate the express of c-fos.This demonstrates CAS model is different from single AS model and is a good one that can simulate brain-gut interaction partly.2.Stimulation such as chronic stress induced 5-HT system and NE system in active state.Under this active state,5-HT system and NE system show stronger reaction to new and acute stress than normal,and this resulted in increased 5-HT and NE contents because CAS can restrain degradation of 5-HT and increase synthesis of NE.In the response to CAS,5-HT system plays a predominant role and NE system plays an adjunctive role in the intestinal tract. It concluded that psychiatric stress can amplify the action other kinds of stimuli.3.The proteins/peptides whose M/Z are 4011.172,29150.9,15213.25Da were different among all groups.The stronger the stress is,the higher protein level is.The three proteins/peptides probably were the most significant.
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