Objective Based on the observation of the changes of symptoms, histopathology, visceral sensitivity, mast cell activation, autophagy, and Beclin-1 and Claudin-2 expression in rats, we established and evaluated a new rat model of diarrhea-predominant irritable bowel syndrome (D-IBS) induced by restraint-stress combined with capsaicin (CAP) administration.Methods Forty healthy 5-week old male Sprague Dawley (SD) rats were randomly divided into normal group, model group I, model group II and model group III, with 10 rats in each group.The D-IBS model was established by restraint-stress combined with intragastric administration of CAP (2 mL/100 g body weight, 0.125% in group I, 0.250% in group II, 0.500% in group III), tail clipping and forelimb restriction for 30 minutes every day for 2 weeks.The rats in the control group were treated with saline for 2 weeks.The number of contraction of abdominal wall and arched back were measured by Power Lab instrument.The mast cell activation was detected using aldehyde-magenta-orange G staining.Light and electron microscopic examinations were performed to detect the morphology and autophagy of colonic tissues.The expressions of Beclin-1 and Claudin-2 in the colonic mucosa were detected by streptavidin-biotin complex (SABC) immunohistochemical staining.Results All rats in the model group III died during the experiment.Compared with the control group and model group I, the stool frequency was increased and the visceral sensitivity threshold decreased in the model group II, and there were statistically significant differences between the model group II and the control and model groups I (P < 0.05).The colonic mucosa, mucosal epithelium and glands in each group showed normal morphology and there was no submucosal vasodilatation and diffuse inflammatory cell infiltration.Except for the control group, round purple-reddish staining spots were observed in the rat mucosal stroma or submucosa in the model groups I and II, indicating an increased expression of mast cells.The autophagy, expressions of Beclin-1 and Claudin-2 in the colonic epithelium were significantly increased in the model group II compared with control group and model group I (P< 0.05).Conclusions The model of D-IBS induced by restraint-stress combined with capsaicin is characterized by increased diarrhea, visceral hypersensitivity, increased mast cell expression and autophagy of intestinal epithelial cells, and disruption of the intestinal mucosal barrier.This model is simple to set up and shows similar symptoms of human irritable bowel syndrome.Therefore, it is worthy of popularization and application.%目的 基于观察大鼠症状学、组织病理学、内脏敏感性、肥大细胞活化、自噬、Beclin-1及Claudin-2等相关指标变化,评价束缚-应激联合辣素灌胃建立一种新的腹泻型肠易激综合征(diarrhea-predominant irritable bowel syndrome,D-IBS)模型研究.方法 清洁级雄性SD大鼠40只,按体重分为正常组、模型I组、模型II组及模型III组,每组10只.模型组均采用束缚-夹尾应激联合辣素(I组0.125%、II组0.250%、III组0.500%)灌胃制备D-IBS模型,正常组予等剂量生理盐水灌胃处理,连续2周.分别应用Power lab仪检测大鼠腹壁收缩次数及弓背次数变化,肥大细胞染色液(醛品红-橙黄G法)检测肥大细胞活化情况,采用光镜、电镜检测大鼠结肠组织病理学及其自噬变化,应用免疫组化SABC法检测大鼠结肠黏膜Beclin-1及Claudin-2表达变化.结果 模型III组大鼠全部死亡,模型II组大鼠大便次数增多,内脏敏感性阈值降低,与正常组及模型I组比较,差异有显著性(P < 0.05);各组大鼠结肠黏膜、黏膜上皮绒毛及腺体形态正常,未见黏膜下血管扩张及弥漫性炎症浸润改变;正常组除外,模型I组、II组大鼠结肠组织黏膜间质或黏膜下层可见类圆形紫红至深紫色染色点,提示肥大细胞表达增多;模型II组大鼠结肠肠上皮细胞自噬、Beclin-1及Claudin-2表达明显增多,与正常组及模型I组相比,差异有显著性(P < 0.05).结论 束缚-应激联合0.25%辣素灌胃建立的大鼠D-IBS模型以腹泻增多、内脏高敏感、肥大细胞表达增高、肠上皮细胞自噬增加、肠黏膜屏障破坏等表现为特点,与人IBS较为相似,该方法简单易行,值得推广应用.
展开▼
