<正>Objective:To investigate the changes of intestinal mucosa tight junctions （TJs） claudin-1

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-4 proteins and mRNA changes in patients with irritable bowel syndrome （IBS） and to elucidate their possible roles in the changes of bowel evacuation habit and formation.Methods:Claudin-1

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-4 proteins and mRNA were evaluated in intestinal mucosa in control group

D-IBS （diarrhea IBS） group and C-IBS （constipation IBS） group with immunohistochemical assay and Realtime-PCR.Results:It was observed that claudin-1

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-4 proteins were localized in the membranes of epithelial cells along the entire length of the plasma membrane including the apical end of the epithelial cells.The claudins were concentrated at the site of TJs only.Claudin-1

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-4 mRNA and claudin-1 protein in small intestinal mucosa and colonal mu- cous in D-IBS group were significantly downregulated （P＜0.05）.Claudin-1

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-4 mRNA and proteins in small intestinal mucosa and colonal mucous in C-IBS group were significantly upregulated （P＜0.05）. There was no significant difference in the expression of claudin-3 protein in both small intestinal mucosa and colonal mucous between D-IBS group and control group（P＞0.05）.Similarly

no significantly differ- ent expression of claudin-4 protein in colonal mucous in D-IBS group was found compared with control group （P＞0.05）.Otherwise

the expression of claudin-4 protein in small intestinal mucosa decreased in D-IBS group （P＜0.05）.Conclusion:Claudin-1

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-4 may play a potential important role in the changes of bowel evacuation habit and formation in patients with IBS.It is not due to the localization changes of claudin proteins in T J

but may be caused by the quantitative changes of the expression of TJ proteins and mRNA.