Objective To study the effect on expression of high mobility group box-1 （HMGB1） mRNA for the expression of zonula occludens-1 （ZO-1） in ileum tissues， and to explore the possible mechanism of intestinal mucosal barrier injury in rats with acute necrotizing pancreatitis （ANP）. Methods Ninety-six male Wistar rats were divided randomly （random number method） into ANP group， ethyl pyruvate （EP）group， and sham operation group. Eight rats of 3 groups were killed to get abdominal aortic blood and ileal tissues at 6， 12， 24， and 48h after operation， respectively.The levels of plasma amylase （AMY） ， D-lactate acid， and the activity of malonyl dialdehyde （MDA） in the ileum tissues were determined by using automatic biochemical analyzer， improved enzymatic spectrophotometry， and thiobarbituric acid （TAB） colorimetry respectively. The pathological changes of ileum tissues were observed under microscopy by HE staining， the expression of ZO-1 protein in ileum tissues was observed by immunohistochemistry （SP method）， and the expressions of HMGB1 mRNA and ZO-1 mRNA in ileum tissues were detected by reverse transcription-polymerase chain reaction （RT-PCR）. Results Compared with ANP group at the same time， levels of AMY， D-lactate acid， and MDA in ileum tissues of EP group were all significantly lower （P＜0.05）. The expression level of HMGB1 mRNA increased at 6 h while ZO-1 mRNA decreased in ANP group. Compared with ANP group at the same time， the expression level of HMGB1 mRNA of EP group was significantly lower while ZO-1 mRNA was higher （P＜0.05）， and the pathological damage in ileum tissues was lighter. Conclusions The decreased expression of ZO-1 in ileum tissues is one of the vitalcauses for intestinal mucosal barrier injury in ANP， and it probably occurs in case of the excessive expression of HMGB1.
ObjectiveTo study the expression of zonula occluden-1 (ZO-1) in ileum tissues and the possible mechanism of intestinal mucosal barrier injury in rats with severe acute pancreatitis (SAP). MethodsFifty SD male rats were randomly divided into sham operation group and SAP group, then SAP group was divided into four subgroups with 10 rats in each subgroup according to the sampling time of 3, 6, 12, and 24 h. The SAP model was made by injecting 5% bovine sodium deoxycholate into biliarypancreatic duct with Aho’s method. The rats were killed at 3, 6, 12, and 24 h after making model. The rats in the sham operation group were killed directly. Tumor necrosis factor-α (TNF-α), diamine oxidase (DAO), and histological changes in pancreatic and intestinal pathologies were observed. At the same time, the ZO-1 protein and mRNA expressions of ileum tissues were detected by immunohistochemistry and RT-PCR, respectively. ResultsCompared with the sham operation group 〔TNF-α: (10.83±0.96) ng/L; DAO: (354.79±3.67) U/L; ZO-1 protein: (10.40±0.45) score; ZO-1 mRNA: 0.878±0.014 8〕, the levels of TNF-α at different time 〔3 h: (125.30±0.94) ng/L; 6 h: (181.89±4.93) ng/L; 12 h: (230.58±1.28) ng/L; 24 h: (198.89±4.83) ng/L〕 were significantly higher (Plt;0.05), the activities of DAO 〔3 h: (235.77±0.67) U/L; 6 h: (117.22±5.58) U/L; 12 h: (106.69±1.39) U/L; 24 h: (91.18±1.09) U/L〕 were significantly lower (Plt;0.05), ZO-1 protein 〔3 h: (8.70±0.22) score; 6 h: (3.73±0.19) score; 12 h: (3.92±0.22) score; 24 h: (4.29±0.30) score〕 and mRNA (3 h: 0.806±0.020 7; 6 h: 0.370±0.015 8; 12 h: 0.502±0.019 2; 24 h: 0.562±0.030 3) expressions of the ileum tissues were significantly lower (Plt;0.05) in the SAP group; Meanwhile, the necrosis of ileum mucous membrane chorioepithelium, angiorrhexis and hemorrhage, and inflammatory cell infiltration in the pancreatic and ileum tissues were also observed. ConclusionThe decrease of expression of ZO-1 in ileum tissues is one of the vital causes for mucosal barrier injury in SAP, probably through acts the excessive release of inflammatory cytokines TNF-α and the decrease of DAO activity.
Objective To investigate the effects and mechanisms of bile on small intestine mucosal barrier.Methods Fifty Wistar rats were assinged into 3 groups randomly: obstructive jaundice (OJ) group （n=20）, biliary external drainage group （n=20） and control group （n=10）. Ten days after operation, the plasma endotoxin level was determinated, the terminal ileum mucosas was obtained to be morphologically measured by light microscope, and immunohistochemistry and Western blot were uesd to examine the expressions of tight junction proteins zona occludens-1 (ZO-1) and occludin in the mucosas. Results Atrophy significantly appeared in the distal ileum mucosas in OJ group. Compared with control group, the intestinal villus height, mucosa thickness and crypt depth in OJ group were obviously decreased 27.8%, 21.7%, and 25.4% (P=0.001, 0.001, 0.040). There were no differences between external drainage group and control group (P=0.050, 0.070, 0.080); While the values of external drainage group were significantly higher than those in OJ group (all P=0.001). The level of plasma endotoxin was up to (1.49±0.27) EU/ml in OJ group compared with control group 〔（0.27±0.09） EU/ml〕, P=0.001. In external drainage group, the value was （0.91±0.25） EU/ml, which was obviously higher than that in control group and lower than that in OJ group （all P=0.001）. Immunohistochemical study showed b positive expression of ZO-1 dropped from 7/10 in the control group to 6/20 in OJ group （P=0.040）, occludin expression was 8/10 in control group and 7/20 in OJ Group （P=0.020）; expressions of them in external drainage group 〔8/20 （P=0.100,0.210） and 9/20 （P=0.060, 0.200）〕 displayed no significant differences compared with the other twogroups. Quantitative testing of Western blot showed the expressions of ZO-1 and occludin in OJ group were significantly lower than those in control group (P=0.001, 0.010), the values in external drainage group were higher than those in OJ group （P=0.005, 0.014）. The expression of ZO-1 was lower in external drainage group than that in control group (P=0.001), and there was no significant difference of occludin between the two groups (P=0.062）. Conclusion Lack of intestinal bile will undermine the intestinal tight junction protein composition, and make intestinal mucosal barrier impaired. The intestinal barrier more severely injured when biliary tract obstructs because of multiple factors. Bile plays an important role in the maintenance of intestinal mucosal barrier.