The Study Of Curcumin On The Mechanism Of Treating DSS-induced Mouse Ulcerative Colitis

Objective: To investigate the effect of curcumin on STAT3 pathway in mice UC, and the effect of curcumin on an enzyme called cyclooxygenase 2(COX2), peroxisome proliferator-activated receptor γ(PPAR-γ), p-STAT3 protein, STAT3 m RNA amount were detected in model of DSS-induced mouse intervened by Curcumin.Methods : The female BALB/c mice 60, weighted of 15 to 25 g, according to the random table were divided into A, B, C, L, M, H six groups, each group of 10.A group:normal group,B group:model group,C group:dexamethasone intervention group(1.5mg/kg.d),L group:Curcumin low dose group(25mg/kg.d),M group:Curcumin moderate dose group(50mg/kg.d),H group:Curcumin high dose group(100mg/kg.d). A group of mice had daily free to access water,the rest of the group of mice had free to access foods and 5% DSS solution 7 days in a row, at the same time daily intraperitoneal injection of drugs in mice were performed:group A mice were injected physiological saline, group B were injected 2.5% ethanol solution,group C were injected dexamethasone, L, M, H group were injected the low, medium and high doses of curcumin. The mouse were daily weighed, and the mice eating, activity, the colour of and shape of the stool, and occult blood, disease activity index score were observed.At the 8th day all of the mice were put to death and the colon were taken out. Part of the colon was used for embedding slice to do HE dyeing for observing colonic histology change, and PPAR gamma and STAT were detected with Immunohistochemistry. Three parts of colon tissue were put in liquid nitrogen backup, one was used in to measure the expression of cox-2 with ELISA, another was used to detect the expression of p- STAT3 with western blotting, another was used to test the expression of a STAT3 m RNA with RT-PCR. Results: 1.group B complianted with UC standards in terms of symptoms and Histology. DAI and histological scores in group B were higher than in group A,but compared with group B,those in group C 、 L 、 M 、 H were decreasing in varying degrees. 2.Immunohistochemical results: The expression of PPARγ of mouse colon in group B(23.00±5.92)was less than that in group A(41.14±9.56)(P<0.01) and that in group C(64.27±20.41)、group L(30.74±7.67)、group M(36.86±16.79)、group H(63.84±20.74)were higher than in group B(P<0.01). The expression of STAT3 of mouse colon in group B(67.12±17.04) was higer than that in group A(27.15±11.91)、group C(29.94±10.38)、group L(44.21±12.84)、group M(29.16±9.03)and group H(20.44±7.30)(P<0.01),and that in M group and C group showed no significant difference(P>0.05). 3.The results of COX-2 expression detected by ELISA: The expression of COX-2 of mouse colon in group B was less than that in group C、L、M、H(P<0.01),and that in group C was higer than that in group L、 M(P<0.01) and that in C group and H group showed no significant difference(P>0.05)but that in group M and group H had significant difference(P<0.01).4.The expression of p-STAT3 of mouse colon detected by western blot. The expression of p-STAT3 of mouse colon in group B was higer than that in group A,less than group C、L、M、H(P<0.05). 5. The expression of STAT3 m RNA of mouse colon detected by RT-PCR method.:The expression of p-STAT3 in group B was higer than that in group A,less than group C、L、M、H(P<0.05).Conclusions: The mechanism of curcumin for treating UC may inhibit STAT3 signaling pathway,reduce the release of COX-2,increase the content of PPAR-γ,decrease neutrophil infiltration and finally attenuate colonic mucosa damage.