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.
Objective To investigate the changes of expression of zonula occludens-1(ZO-1) in rats with severe acute pancreatitis (SAP), and to study the relationship between the ZO-1 protein and microvascular injury in rats with SAP. Methods Forty-eight Wistar rats were randomly divided into sham-operation (SO) group and SAP group, each group enrolled 24 rats. Pancreas of rats in SO group were flipped only after laparotomies, but rats of SAP group were injected with 5% sodium taurocholate by retrograding cholangiopancreatography micro pump to produce the SAP model. At 6, 12, and 24 hours after operation, 8 rats were sacrificed to get abdominal aortic blood for testing the levels of peripheral blood amylase, trypsin, interleukin-8(IL-8), tumor necrosis factor-α(TNF-α), and ZO-1 protein. At the same time, pancreatic tissues were got to perform HE staining and immunohistochemical staining for observation of the pathological changes and the expression of ZO-1 protein respectively. Results Compared with SO group at the same time, the levels of peripheral blood amylase, trypsin, IL-8, TNF-α, and ZO-1 protein were all higher in SAP group (P < 0.05). The level of amylase in SAP-24 hours group was higher than those of 6 hours group and 12 hours group(P < 0.05), the levels of trypsin, IL-8, and ZO-1 protein in SAP group increased over time (P < 0.05), but levels of TNF-αin 3 time points of SAP group did not differ with each other significantly(P > 0.05). Results of regression showed that in the SAP group, the level of ZO-1 protein in serum was significantly positive correlated with pathological score of pancreatic tissue(b=0.96, P < 0.05), levels of serum amylase(b=0.87, P < 0.05), trypsin(b=0.72, P < 0.05), and serum IL-8 (b=0.69, P < 0.05), but was not significantly correlated with level of TNF-α(P > 0.05). HE staining results showed that damage of pancreatic tissues became worse over time in SAP group, and the pathological score of SAP-6 hours group was lower than those of 12 hours group and 24 hours group (P < 0.05). Immunohistochemical staining results showed that, in SAP group, with the extension of time, the number of ZO-1 protein granules in pancreatic acinar cells and capillary wall reduced, and expressed in capillaries discontinuously. Conclusion During the course of SAP, the concentration of serum ZO-1 protein increase, but its expression in the pancreatic tissue degrade, which is closely associated with microvascular injury and progression of pancreatic tissues.