动物模型,克罗恩病 z-bo 2020-08-07 573

　　(1) Method of replication: Adult rats, fasting without water for 48 hours, are anesthetized with pentobarbital sodium by intraperitoneal injection, insert the neonatal gastric tube from the anus into the intestine to a depth of about 8 cm, and inject it containing trinitrobenzene sulfonic acid (2 ,4,6-Trinitrobenzene sulfonicacid, TNBS) 30mg solution 0.9ml/piece. The solution is composed of 0.6 ml of 5% TNBS and 0.3 ml of 100% absolute ethanol. After the animals were awake, they were kept in a clean environment. They were observed daily for their attitude, activity, appetite, weight, and stool characteristics. They were sacrificed at regular intervals, the colon was separated, the intestinal cavity was cut along the mesentery, and the appearance of the colon was visually inspected. The colon, transverse colon, ascending colon, and the most severely affected intestinal segment were taken at 3, 8cm. Routine paraffin embedding, sectioning, HE staining, and tissue morphological examination with optical microscope.

　　(2) Model characteristics: Model animals developed laziness, anorexia, diarrhea, dark red stools, occult blood test (++++), weight loss after 1 day of injection, and the symptoms were the worst at 3 days, and the animals began to improve after 5-6 days; Diarrhea usually lasts for 2 weeks, and the fecal occult blood test still shows (+)～(++) at 3 weeks. Macroscopic observation shows: 1 day after injection, the colon turns brown and black, the intestinal wall is congested and edema, there are multiple large erosions, and it is slightly adhered to the surrounding tissues; 3 days, the intestinal wall of the lower colon has severe segmental erosions and necrosis. One ulcer was formed, and the intestinal wall was severely adhered to the surrounding tissues. At 7d, erosion and necrosis were reduced, but multiple deep ulcers and severe adhesions appeared; at 14d, adhesions were reduced, no erosion and necrosis were seen, and the surface was similar to Ah Phthalic superficial ulcers and paving stone-like changes, the intestinal wall is obviously thickened, the original deep large ulcers have begun to heal, and some rats have segmental lesions; at 21d, the intestinal lesions have improved significantly and the ulcers have healed. Healing scars can be seen, but the intestinal wall is thickened and the diseased intestine is narrowed. At 28 days, the intestinal wall has no ulcers, but the intestinal wall is still thicker than normal. Under light microscope: 1 day after injection, hemorrhagic inflammatory lesions were diffusely distributed in the mucosa and submucosa, with massive necrosis of epithelial tissue and severe submucosal edema. A large number of neutrophils and red blood cells are infiltrated, but the muscle tissue is still intact; at 3 days, the lesions are further aggravated, and full-thickness transmural inflammation appears, forming large ulcers that reach the muscle layer. Inflammatory cell infiltration increases, but no hidden Fossa abscess; on the 7th day, obvious fissure-like ulcers and full-thickness transmural inflammation are seen. The infiltrating cells are mainly neutrophils and some monocytes and lymphocytes. Vascular proliferation begins to appear. Obvious granulation tissue is seen, occasionally Crypt abscess; at 14 days, inflammation is lessened than before, ulcers become smaller and shallower, a large number of inflammatory cells infiltrate under the mucosa, fibrous connective tissue hyperplasia, typical granuloma formation, glandular goblet cells decrease, but the gland arrangement is generally not Deformation and occasional polypoid changes; at 21d, the mucosal layer is basically normal, but there is still a large amount of inflammatory cell infiltration under the mucosa, and ulcers that have begun to heal can be seen, fibrous connective tissue and vascular hyperplasia are obvious; at 28d, except for the most severe part of the disease There were a large number of monocytes, lymphocytes, and plasma cells infiltrated under the mucosa of the section, and nodules appeared. Other sections only showed mild submucosal and lamina propria inflammation.

　　(3) Comparative Medicine Crohn’s disease is a systemic disease with unknown etiology that mainly affects the digestive tract. It is one of the main types of non-specific inflammatory diseases in the intestinal tract. The current popular view is that when a genetically susceptible body loses immune tolerance to gastrointestinal antigens, autoimmune response becomes a key factor in the occurrence and development of Crohn's disease. This experiment is actually a copy of an immunological model. TNBS itself is a kind of hapten. It first destroys the intestinal mucosal barrier through the chemical action of ethanol, then enters the local intestinal tissues, and becomes a complete antigen after binding to tissue proteins, triggering the body's immune response and leading to intestinal inflammation. . Its pathological changes are mainly manifested as: obvious fissure-like ulcers on the mucosal surface of the colon wall, full-thickness transmural inflammation, thickening and hardening of the intestinal wall at the lesion, high edema of the intestinal mucosa, and superficial ulcers similar to aphthous in folds And paving stone-like changes, serious adhesion between the intestinal wall and surrounding tissues. These changes have many similarities with the pathological features of human Crohn's disease. The disease period of this model is more than 28 days, and the acute inflammation period is about 1 week. The acute phase is mainly manifested as hemorrhagic inflammation, with a large number of neutrophils exuding and ulcer formation; the chronic phase is manifested as full-thickness transmural inflammation, deep fissure ulcers, fibrous connective tissue hyperplasia, massive inflammatory cell infiltration and granuloma formation . In addition to histologically similar to human lesions, short modeling cycle, simple method (only one-time enema operation), small individual differences, longer inflammation duration, and high modeling rate are also important features of this model . As one of the means for verifying, evaluating and screening the efficacy of drugs or active substances for treating Crohn’s disease, this model should make a difference.