动物造模,急性溃疡性结肠炎动物模型 z-bio 2021-11-15 854

　　(1) Breeding method Anesthetized adult male rats by intraperitoneal injection of sodium pentobarbital, fasting for 16 hours, deprived of water, slowly inserting the polyethylene catheter from the colon at 8 cm from the anus into 1.5 to 2 ml of 8% acetic acid solution . After 20 seconds, inject, inject 5 ml of saline and repeat the flushing 3 times. After enema, observe the animal's daily activities and record the weight, diarrhea and bloody stools. Ten days later, the animals were sacrificed and the changes in the colonic mucosa were observed with naked eyes. The material was harvested and fixed in a 10% formaldehyde solution. The morphological changes of the colonic mucosa were examined by optical microscope and immunohistochemical techniques. Tumor necrosis. Measure the factor α of the colonic mucosa (TNF-α).

　　(2) Model characteristics After enema for 1-3 days, the animals showed sluggish hair, laziness, curly hair, reduced diet, weight loss, and began to show various degrees of bloody diarrhea. Ten days later, autopsy and observation showed that the sigmoid colon and descending colon above the rectum continued to be edema, the intestinal wall was significantly thickened, the duct wall was hard, and the mucosal surface was diffused with bleeding spots, erythema, and edema. Colonic mucosal epithelium has diffuse and ulcers, submucosal edema, vascular congestion, crypt abscess, goblet cell depletion, neutrophils diffuse and lymphocyte infiltration in the appropriate layer, and these cells are basic and immature cell. Mucosal TNF-α increased, and IL-10 decreased.

　　(3) Comparative Medicine Ulcerative colitis (UC) is a chronic inflammatory and ulcerative disease of the colonic mucosa. The most typical clinical feature is bloody diarrhea. Pathological changes are mainly manifested as mucosal epithelial cells, capillary obstruction, lamina propria plasma cells, eosinophils, lymphocytes, mast cells and neutrophils under reticular fibrosis. Sexual infiltration, crypt abscess, and necrosis lead to epithelial and mucosal ulcers. By injecting acetic acid into the rectum of animals, the above-mentioned symptoms and pathological symptoms can be better simulated. The mechanism is to use the chemical stimulation of acetic acid to cause the destruction of the colonic mucosal barrier structure, thereby causing inflammation and cell necrosis. Using acetic acid intestinal perfusion, model animals will have different degrees of bloody diarrhea, sigmoid colon and descending colon have persistent edema, epithelial irritation, crypt abscess and lamina propria neutrophil proliferation, showing spherical and lymphocyte infiltration. In addition, the colonic mucosa of this model animal increased TNF-α and decreased IL-10, similar to the clinical manifestations of human UC patients. There is evidence that immune factors are important factors involved in the development of UC, among which cytokines play a non-negligible role. Among them, TNF-α and IL-10 play a positive role in the etiology of UC. TNF-α is mainly produced by activated monocytes-macrophages. It is a cytokine with a variety of biological activities. The cascade reaction will accumulate white blood cells in the inflamed area, stimulate monocytes, vascular endothelial cells, etc. to produce cytokines, induce cytokine synthesis, and ultimately lead to tissue damage. IL-10 is called a cytokine synthesis inhibitor and is mainly produced by monocytes and macrophages. Its main function is to inhibit the activation of monocytes, macrophages, neutrophils and T cells. These activations are effectively inhibited at the mRNA level. Inhibit activation. Monocytes produce IL-18, IL-6, IL-8, TNF-α and other pro-inflammatory cytokines, which play an important role in regulating the immune balance of the intestinal tract. Acetic acid enema is used to replicate the animal model of ulcerative colitis. The concentration of acetic acid and the residence time in the colon are important techniques. Generally, ψ (acetic acid) = 4% to 10%, and the most common exposure time is 15 to 30 seconds. The model has a simple manufacturing method, low cost, short cycle, obvious symptom characteristics and typical pathological symptoms. The levels of cytokines in diseased tissues are similar to those in human UC patients. It is one of the most widely used experimental UC models today, used for the screening and efficacy evaluation of the etiology and active substances of UC. However, the damage caused by acetic acid directly stimulating the colonic mucosa is non-specific inflammation, which is an acute process and cannot be manifested as the chronic and recurrent characteristics of human UC, which leads to acute damage to model animals. Healed spontaneously within 3 weeks. If insufficient, the application of the model will be limited.