动物造模,IBD z-bo 2022-02-02 427

　　Since the 1960s, the chemical induction method has been started very early, and has become the most mature and commonly used method for preparing IBD models. There are many types of chemical stimulants, such as acetic acid, sodium dextran sulfate, sodium peroxynitrite and carrageenan. The chemical irritation modeling category often includes 2,4-dinitrochlorobenzene (DNCB), 2,4,6-trinitrobenzene sulfonic acid (TNBS), 2,4-dinitrobenzene sulfonate (DNBS) )Wait. Therefore, this concept needs to be clarified. The mechanism of chemical stimulation is that chemicals directly stimulate the intestinal mucosa, resulting in cell damage, increased vascular permeability and activation of certain inflammatory factors. In this process, an immune response will inevitably occur. However, this reaction process is essentially different from intestinal immunoreactive enteritis (see below). When DNCB, TNBS, etc. directly act on the intestine (or combined with ethanol, acetic acid, etc.) without sensitization, especially when enteritis develops after a single use, it can be regarded as a chemical stimulation model.

　　1, acetic acid model

　　[Modeling mechanism] Acetic acid directly stimulates the intestinal mucosa, causing epithelial necrosis and vascular damage, and enhancing vascular permeability. Acetic acid activates quinine, promotes fibrin hydrolysis, prevents coagulation and activates epoxidation. Enzyme and lipoxygenase pathways cause inflammation. [Modeling method] Wistar rats were lightly anesthetized with ether, a polyethylene catheter with an outer diameter of 2 mm was inserted into the colon 8 cm away from the anus, and 2 ml of 3% acetic acid was slowly injected and completed within 10 seconds injection. Then rinse with 5 ml of saline 2, and then lie on the ground with your head lowered, and raise your feet for 30 seconds to prevent liquid from flowing out of the large intestine. After 5 days, the animal will have diarrhea, blood in the stool, weight loss, mucosal hemorrhage, epithelial necrosis, submucosal edema, neutrophil infiltration, etc. Inflammation can extend to the lamina propria, submucosa and even the muscle layer. [Model features] are temporary non-specific mucosal damage and acute inflammation. Powerful self-repair ability. Its inflammatory mediators are similar to human acute enteritis. The disadvantage is that it cannot accurately reflect the immunological changes of human UC, and cannot show the chronicity and recurrence of human UC.

　　[Model Evaluation and Application] The model is simple, easy to implement, low cost, short cycle, good repeatability, and high success rate. It is suitable for studying the acute phase of human UC, the mechanism of inflammation caused by inflammatory mediators and the mechanism of drug therapy, but it is not suitable for the study of immune mechanisms. The key to the successful introduction of the model is the concentration and duration of action of acetic acid, which is suitable for causing diffuse, non-perforated inflammation.

　　2. Model of dextran sodium sulfate [modeling mechanism] dextran sodium sulfate (DSS) is a sulfated polysaccharide synthesized from sucrose, which has the same hemostatic and anticoagulant effects as heparin. The mechanism of DSS-induced ulcerative colitis may be related to its inhibition of DNA synthesis, epithelial cell proliferation, and destruction of the intestinal mucosal barrier (intestinal flora enters the lamina propria). Causes migration and leads to excessive activation of macrophages and Th1/Th2/Th17 cell function, which is related to disability.

　　[Modeling method] BALB/c mice, male and female, 8-9 weeks, 16-18 g, 5% DSS, distilled water. Scheme 1: The mice freely ingest 5% DSS for 7 days, and then change to distilled water for 10 days to release them, forming a cycle of an acute UC model. Scheme 2: According to Scheme 1, the mice complete 4 cycles and transform into a chronic UC model. Animals were sacrificed 7 days after the end of the first cycle (acute phase) or the fourth cycle (chronic phase). As a result, 4 to 5 days after starting the modeling, diarrhea occurred in the acute phase mice, and the occult blood test was positive. The disease spreads from the anus to the mouth, with the rectum being the most serious. Mucosal hyperemia and edema, erosions and ulcers scattered in the lesion site. The mucosa and submucosa mainly infiltrate neutrophils. In chronic mice, not only did diarrhea and bloody stools occur at the same time in the acute phase, but also bloody stools and diarrhea were seen 5 to 6 days after the withdrawal of DSS, colonic granulation tissue growth, loss of mucosal structure and loss of glands. Malformations, atrophy and shortening of the intestine were also found. The mucosa and submucosa mainly infiltrate lymphocytes, plasma cells and macrophages. [Model Features] In the chronic phase and acute onset of chronic diseases, it is more consistent with the clinical features of human IBD. It can be used to study the pathological characteristics of human IBD in the acute and remission phases. Colonic mucosal lesions are mainly on the left side, which can cause colonic epithelial atrophy and abnormal development, thereby increasing the risk of cancer. This is similar to how human UC can become cancer.

　　[Model Evaluation and Application] IBD occurs when animals drink DSS freely, and the interference of human factors is minimized when the model is established. The method is simple, easy to implement, reproducible, long and short cycle, and suitable for the acute and remission phases of UC. Precise control of the amount of DSS consumed by animals will further reduce the difference between model lesions. This model is usually used to screen UC-related colorectal cancer prevention and treatment drugs.