| Ulcerative colitis (UC),also named nonspecial ulcerative colitis,is achronic disease featuring recurrent inflammation of the colonic mucosawithout the certain pathology and effective measures to block itspathophysiological process directly.The clinical manifestation of UC comprisemucus pus and blood stool,diarrhea,abdominal pain,tenesmus and so on.It wasfound that cytokines,adhesion molecules,inflammatory mediums,oxygenradicals participate in the processes of UC.The peptide transporters PepT1belong to the peptide transporter (PTR) family and serve as integral membraneproteins for the cellular uptake of di-and tripeptides in the organism. PepT1isnormally expressed in the brush border membranes of enterocytes in theproximal intestine, but poorly or not expressed in the colon.This oligopeptidetransport is ensured by the proton-dependent transporter PepT1.After theirtransport into cells, the small peptides primarily undergo intracellularhydrolysis to free amino acids for delivery into portal blood. Therefore PepT1plays a key role in the regulation of nitrogen supply.In addition, PepT1isresponsible for the uptake and tissue distribution of a wide range ofpharmaceutically important compounds, including β-lactam antibiotics,angiotensin-converting enzyme inhibitors, anti-cancer and anti-viraldrugs.Expression of the di/tripeptide transporter PepT1has been observed inthe colon under inflammatory conditions, however, the inducing factors andunderlying mechanisms remain unknown.Objective: To investigated the expression and pathological mechanism ofPepT1which is involved in a rat UC model induced with dextran sulfatesodium(DSS).To observe the effects and therapeutic mechanism of Compoundshuang-ling antidiarrhea powder,which is a pure Chinese traditional medical herb, with effects of anti-inflammatory, bacteriostasis, diuresis,immunoregulation and curing abdominal pain and emetocathartic in UC.Methods: Sprague-Dawley(SD)were divided randomly into9groups(n=10in each group),including normal control(N)group,after the modelwas established, diarrhea model (DM)groups were administered water(2days,4days)respectively;negative control (NC)groups were administeredsaline(2days,4days)respectively; Dose-compound shuang-ling antidiarrheapowder treatment (D)group were administered compound shuang-lingantidiarrhea powder (2days,4days)respectively,0.31g/kg, twice a day;positive control (PC)group were administered Wan-xin-mu-zai-kuai-kang(2days,4days)respectively,0.31g/kg,twice a day.The samples of colon tissuewere taken at the end of the test to observe the pathological changes byhematoxylin-eosin staining.Daily disease activity index (DAI) andhistopathological score(HI) were evaluated.The expression of PepT1in colontissue was determined by Immunohistochemical technique and Westernblot,reverse transcription polymerase chain reaction(RT-PCR) technique wasused for the PepT1mRNA expression, and compare and analyze thediffererces between the groups.Results: Pathological change in colon tissue of rats of DM group is closeto change of ulcerative colitis in human.Rats presented severe diarrhea,evenbloody stools,mucous stools,pus stool.Their general conditions showed adeclining trend,their weight was decreased either.HE: Histologicalexamination showed that typical inflammatory changes in colonic architecturewere observed,such as mucosal congestion,the thickening of the colonwall,lost of epithelial cell,distorted glands,ulceration,crypt dilation,and gobletcell depletion,as well as infiltration of inflammatory cell composed mainly ofmacrophages,lymphocytes and plasma cells.Administration of dose-compoundshuang-ling antidiarrhea powder and Wan-xin-mu-zai-kuai-kang significantlyameliorated the symptoms of colitis.The DAI in group N(3dDM,6dDM,3dNC,6dNC,3dD,6dD,3dPC,6dPC) were (0±0,3.734±0.263,3.635±0.191,3.702±0.189,3.568±0.164,2.297±0.104,1.199±0.233,2.365±0.191, 1.232±0.225)respectively.The DAI in the UC model group were much higherthan those in the control group(P<0.05).Compared with DM group,the DAIscore in NC group (3d,6d) had no statistical significance(P>0.05);the DAIscore in D group (3d,6d) markedly decreased and the difference wassignificant(P<0.05); the DAI score in PC group (3d,6d) markedly decreasedand the difference was significant(P<0.05). The DAI in3dD group were muchhigher than6dD group(P<0.05); The DAI in3dPC group were much higherthan6dPC group(P<0.05).There was no statistical significance between3dDand3dPC group(P>0.05). There was no statistical significance between6dDand6dPC group(P>0.05). The HI in group N(3dDM,6dDM,3dNC,6dNC,3dD,6dD,3dPC,6dPC)were0.1±0.316,7.5±1.179,7.2±0.919,7.6±0.843,7.1±0.994,4.9±0.994,2.5±0.707,5.2±0.919,2.6±0.699respectively.The HI inthe UC model group were much higher than those in the control group(P<0.05).Compared with DM group,the HI score in NC group (3d,6d) had nostatistical significance(P>0.05);the HI score in D group (3d,6d) markedlydecreased and the difference was significant(P<0.05); the HI score in PCgroup (3d,6d) markedly decreased and the difference was significant(P<0.05).The HI in3dD group were much higher than6dD group(P<0.05); The HI in3dPC group were much higher than6dPC group(P<0.05).There was nostatistical significance between3dD and3dPC group(P>0.05). There was nostatistical significance between6dD and6dPC group (P>0.05).Immunohistochemstry indicated that the expressions of PepT1were detectedmainly in brush border membranes (BBMs) of enterocytes in large intestineamong each group,other than control group.As shown by Western Blotting andRT-PCR analysis,there was no expression of PepT1in control group;theexpression level of PepT1in DM and NC groups were much higher thanintervention groups(P<0.05).3dD group were much higher than6dD group(P<0.05);And3dPC group were much higher than6dPC group (P<0.05).There was no statistical significance between3dD and3dPC group(P>0.05).There was no statistical significance between6dD and6dPC group(P>0.05). Conclusion:17days DSS administration in drinking water of SD rats could resultin an acute inflammation of the colon.2PepT1,when is present at high levels in inflammatory colontissues,could play a important role involved in the developing of UC.3Dose-compound shuang-ling antidiarrhea powder could effectivelyalleviate the symptoms of DSS-induced acute UC,reduce DAI score andhistological score. |
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