The Experimental Research On Alteration Of Gut Function Following Intestinal Obstruction In Rats

Objective:To investigate the changes of absorption and barrier function of gut in setting of intestinal obstruction in rats in order to explore pathophysiological variations under intestinal obstruction of different severity.Methods:A simple partial and complete intestinal obstruction animal model were established by ligating the lower part of small bowel of rats with plastic loop. Samples were collected on the POD 3, 5 and 7 respectively. The perimeter of gut proximal to obstruction site was measured and the morphological changes were observed pathologically. The absorptive function of obstructed gut was estimated by D-xylose absorptive test and detection of expression of SGLT1 & PEPT1 mRNA in small bowel using fluorescent real-time quantitive RT-PCR. The mechanical barrier was assessed by determining the expression of occludin, tight junction protein of intestinal mucosa , by immunofluorescence and Western Blot method, and measurement of DAO level in peripheral blood serum and liquid chromatography essay of lactulose mannitol ratio in urine. Protein content in the obstructed small bowel mucosa and the sIgA content in faeces were also measured to evaluate immune barrier function. Assessment of endotoxin in portal vein and bacterial culture of the mesenteric lymph nodes, liver and spleen were performed to interpret the intestinal bacterial translocation. TNF-αlevel in blood serum was measured to indicate the occurrence of SIRS.Results:1. At the same check point, the perimeter of the small bowel in the experimental groups was significantly increased compared to control. There was significant difference between the experimental groups on POD 3, but not on POD 5 and 7.2. With the development of the intestinal obstruction, the mucosa necrosis from mild to serious was found in the experimental groups.3. The D-xylose level in blood serum decreased significantly on POD 7 in the experimental groups. 4. The expression of SGLT1 mRNA decreased significantly on POD 5 in the complete obstruction group and on POD 7 in the partial obstruction group.5. The expression of PEPT1 mRNA decreased significantly on POD 5 in the complete obstruction group. Although it was found that there was little depress in the partial obstruction group on POD 7, no significant difference with the control was identified.6. D-xylose level was found correlate with the expression of SGLT1 mRNA.7. The intestinal epithelial tight junction protein occludin was localized on the surface of cell membrane, among the cells and in the cell plasma. Half quantity analyze on occludin expression was determined by Western Blot. On the POD 5, it depressed significantly in the experimental groups.8. The DAO level in blood serum and L/M in urine increased significantly on POD 3 in the complete obstruction group and on POD 5 in the partial obstruction group respectively.9. The protein content in the obstructed small bowel mucosa decreased significantly on POD 5 in the complete obstruction group and on POD 7 in the partial obstruction group respectively.10. The sIgA content in faeces decreased significantly on POD 5 in the complete obstruction group and on POD 7 in the partial obstruction group respectively.11. The endotoxin level in portal vein increased significantly on POD 3 in the complete obstruction group and on POD 5 in the partial obstruction group respectively.12. The colony counts of the mesenteric lymph nodes, liver and spleen increased significantly on POD 3 in the complete obstruction group and on POD 5 in the partial obstruction group respectively.13. The TNF-αlevel in blood serum rised significantly on POD 3 in the complete obstruction group and on POD 5 in the partial obstruction group.14. It was found that endotoxin level hold positive correlation with the DAO and TNF-αlevel, but negative correlation with sIgA content in Spearman correlation analysis.Conclusion: 1. The perimeter of the small bowel increased after intestinal obstruction and mild to serious mucosa necrosis occurred.2. The expression of SGLT1 and PEPT1 mRNA depressed under intestinal obstruction and resulted in absorptive dysfunction.3. The expression of the intestinal epithelial tight junction protein occludin decreased after intestinal obstruction and enhanced permeability of the gut.4. The gut immune barrier dysfunction was caused by the decreasing of protein and sIgA contents.5. SIRS was induced by the bacterial translocation under intestinal obstruction because of hyperpermeability and damaged immune barrier of gut.