RÉSUMÉ
Objective By simulating acute hypoxic conditions, an experimental model of intestinal stress injury in plateau mice was established to explore the pathogenic mechanism of acute gastrointestinal diseases in plateau, and to lay foundation for preventive and therapeutic measures.MethodsThirty-six SPF-grade adult male BALB/c mice were randomly divided into four groups: normoxic 24 h, normoxic 72 h, hypoxic 24 h, and hypoxic 72 h, based on body weight using a randomized numerical table method, with nine mice in each group. Mice in the normoxic group were kept in a conventional barrier environment, while those in the hypoxic group were placed in a hypoxic chamber within the barrier environment with oxygen concentration set at 10% to simulate plateau conditions. They were subjected to stress for 24 h and 72 h, respectively, in order to establish a model of intestinal injury induced by acute hypoxia. After modeling, the mice were weighed, anesthetized with 1% pentobarbital sodium, and then euthanized by cervical dislocation. Duodenal and colonic tissues were collected. Histopathological morphology of intestinal tissues was observed after HE staining. Western blotting and immunohistochemistry were used to detect the expression levels of tight junction-related proteins in intestinal tissues. Real-time fluorescence quantitative PCR was performed to measure the expression levels of inflammatory cytokines and chemokines. TUNEL staining was used to assess apoptotic activity of intestinal epithelial cells, thus evaluating intestinal injury-related phenotypes in this model.Results Compared with the normoxic groups, mice in the 24 h and 72 h hypoxia groups showed weight loss, shortened duodenal villi, abnormal crypt structure, and decreased villus/crypt ratio. The colonic mucosa was infiltrated with inflammatory cells and irregular crypt structure. Expression levels of Occludin and zonula occludens-1 (ZO-1) were significantly decreased in duodenal and colonic tissues of mice in the 24 h and 72 h hypoxia groups (P<0.05). The expression of pro-apoptotic protein Bax was significantly up-regulated while expression of anti-apoptotic protein Bcl-2 was significantly down-regulated in duodenal tissues (P<0.05). Apoptotic activity of intestinal epithelial cells was significantly enhanced (P<0.05). In addition, interleukin (IL)-1β, IL-6, monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor-α (TNF-α) mRNA levels were significantly increased in duodenal tissues after 24 and 72 h of hypoxic stress(P<0.05). After 24 h of hypoxic stress, there was no significant change in the expression levels of inflammatory cytokines in colon tissues (P>0.05), but after 72 h, the expression levels of pro-inflammatory factors IL-1β, TNF-α, IL-6, MCP-1, and anti-inflammatory factor IL-10 mRNAs significantly increased in colon tissues of mice (P<0.05).Conclusion The usage of a hypoxia chamber to simulate an acute hypoxic environment in plateau can lead to abnormal intestinal tissue structure, intestinal barrier dysfunction, and induce intestinal epithelial cell apoptosis, triggering an intestinal inflammatory response in stress mice. These findings indicate the successful construction of a mouse model for an acute hypoxic stress-induced intestinal injury.
RÉSUMÉ
Objective Given that psychosocial stress can contribute to a series of diseases,such as inflammatory bowel disease and irritable bowel syndrome,we aimed to establish an experimental chronic restraint mouse intestinal stress injury model as a basis for exploring the pathogenic mechanism of chronic restraint stress-induced gastrointestinal diseases,and for developing preventive and curative measures.Methods Eighteen male SPF-grade BALB/c mice were acclimatized for 7 days and then divided into a control group and a chronic restraint stress group according to body weight,using a randomized numerical table method.The mice were subjected to restraint stress for 3 hours per day for 14 days to establish an intestinal injury model.The model was evaluated by observing body weight,pathological changes in intestinal histomorphology,expression of tight junction proteins,apoptosis of intestinal epithelial cells,and mRNA expression levels of inflammatory cytokines.Results After 14 days of chronic restraint stress,model mice showed weight loss,shortened duodenal villus height,abnormal crypt structure,a decreased villus/crypt ratio,colonic mucosal inflammatory cell infiltration,and irregular crypt structure.Protein immunoblotting,immunohistochemistry,and immunofluorescence staining showed that the expression levels of the duodenal and colonic tight junction proteins Occludin and Claudin-1 were significantly decreased in mice after chronic restraint stress(P＜0.05),while expression levels of the apoptotic protein cleaved-caspase-3 in intestinal epithelial cells were significantly increased(P＜0.05).Regarding the mRNA expression levels of intestinal inflammatory factors and chemokines,chronic restraint stress for 14 days significantly increased the gene expression levels of interleukin(IL)-1β,IL-6,monocyte chemoattractant protein-1(MCP-1),tumor necrosis factor-α,and IL-10 in the duodenum of mice(P＜0.05),and significantly increased the gene expression levels ofIL-1β,IL-6,and MCP-1 in the colon(P＜0.001).Conclusions The use of a behavioral restriction device to restrain mice continuously for 14 days led to abnormal intestinal tissue structure,intestinal barrier dysfunction,and intestinal epithelial cell apoptosis,and triggered an intestinal inflammatory response in the stressed mice,indicating successful establishment of a mouse model of intestinal injury by chronic restraint stress.