动物造模,药效评价,慢性胃溃疡 z-bio 2024-08-26 439

　　(1) Method of replication: BALB/c mice, SPF grade, 5-7 weeks old, fasted for 12 hours, anesthetized and opened the abdomen. A No. 2 surgical cotton thread containing corrosive drugs (soaked in 15% carbolic acid and 25% acetic acid solution) was placed across the gastric wall at the posterior wall of the greater curvature of the stomach. The two needle points were spaced 1-1.5 rnrn apart, and the cotton thread was cut. The abdominal cavity was closed according to surgical requirements, and the skin was sutured. After 2 hours, normal water supply and feeding were restored. The next day, fasting for 12 hours and intraperitoneal injection of ranitidine 0.25mg/animal for 4 hours, Hp bacterial solution identified by microbiology and PCR was administered by gavage at a dose of 14 × 100000000CFU/animal. At different times after Hp administration, the cervical vertebrae were dislocated and euthanized. The gastric antrum mucosa and homogenate were taken for bacterial clone growth observation, urease and PCR identification, and partial gastric mucosal tissue was taken for examination using light and electron microscopy techniques. Or Mongolian gerbil (MG), 8-week-old, fasted and deprived of water for 12 hours, orally administered 0.3ml/mouse with 50% ethanol, and then continued to fast and deprive of water. The next day, 0.5ml/mouse with 1000000000000 CFU/L Hp bacterial solution was orally administered once in the morning and once in the afternoon, and once again in the morning the next day. Or SPF grade 6-week-old MG, fasting and water deprivation for 24 hours, subcutaneous injection of 20mg/kg body weight of indomethacin, gavage of 0.5ml/animal of Hp bacterial solution after 6 hours, followed by fasting for 4 hours, continuously gavage for 3 days, once a day. At 12 weeks, fasting and water deprivation were carried out for 24 hours. Blood was drawn from the eyeballs, serum was separated, and anti Hp antibodies were detected by ELISA. At the same time, the stomach was opened and dissected along the greater curvature of the stomach. The residual material in the stomach was gently washed away with physiological saline, and the general condition of the gastric mucosa was observed with the naked eye. Then, half of the mucosal tissue was cultured, smeared, and subjected to rapid urease paper test. The other half of the mucosal tissue was fixed with 10% formaldehyde for histopathological examination.

　　(2) Model characteristics: When cotton thread with corrosive drugs was hung under the mucosa of the greater curvature of the stomach in the model mice for 2 weeks, ulcers with diameters ranging from 1-2.5mm appeared in the gastric antrum. Local gastric mucosal glandular defects were observed, with fibrous substances oozing out and inflammatory cell infiltration visible under the mucosa. At the same time, after being cultured in Hp conditioned medium for 3 days, milky white colonies were observed growing on the gastric mucosa, and their bacterial moss urease test was positive. PCR reaction showed specific DNA amplification bands. At 72 days, electron microscopy observation revealed the presence of flagellated Helicobacter pylori in the gastric mucosa. After 12 and 24 weeks of ethanol combined with Hp infection, about 37% of MG models showed significant bleeding, chronic active gastritis, and ulcers in the gastric mucosa. Sometimes ulcers could penetrate deep into the muscle layer. At the same time, a large amount of Hp could be clearly observed in the mucus on the surface of the gastric antrum, pylorus, and gastric body mucosal epithelial cells, in the gastric glandular fossa, and between epithelial cells. The Hp infection rate reached 100%. After 12 weeks of exposure to indomethacin and Hp infection, a large number of inflammatory cells infiltrated the gastric mucosa of the MG model, and a large number of lymphoid follicles formed in the mucosal and submucosal layers. About one-third of the animals had gastric ulcers in the antrum.

　　(3) Comparative medical research has found a close relationship between Hp infection and the formation and development of gastric ulcers. Hp has a certain affinity for gastric epithelial cells and can quickly penetrate the tight junctions between epithelial cells through the mucus layer, causing infiltration of inflammatory cells in the mucosa, destruction of surface epithelial cells, and decreased mucosal resistance; The extracellular protease released by Hp can cleave the aggregated structure of mucin glycoproteins, preventing mucin from forming colloids and disrupting the integrity of the mucosal barrier; The large amount of urease secreted by Hp can rapidly break down urea and produce a large amount of ammonia, which can cause changes in the surrounding environment of epithelial cells, increase pH, hinder the entry of H+from the gastric fundus gland into the gastric cavity, and promote the reverse diffusion of H+, leading to the formation of gastric ulcers. In addition, Hp can also produce some chemotactic inflammatory cytokines such as lipopolysaccharides, making chronic inflammatory mucosa more susceptible to damage from gastric acid. Although the natural infection rate of Hp in humans is quite high, it is quite difficult to colonize human derived Hp into small experimental animals by gavage. This is not only because the quality of Hp colonization is related to animal host specificity, but also to animal grade and Hp strain invasiveness. Relatively speaking, the small animals that are relatively easy to colonize are sand rats, with animal grades of sterile or SPF. Hp strains are highly invasive strains, which refer to strains with high virulence, motility, and adhesion obtained through clinical isolation screening and animal domestication. During the replication process of this model, ranitidine was pre injected intraperitoneally with the aim of increasing the pH value of the animal's gastric mucosa (with an average value of 1 to 5), so that Hp bacteria entering the gastric cavity by gavage can survive in a microenvironment that has not yet decomposed urea and established strong acid resistance, thereby enhancing the ability of Hp bacteria to colonize in the gastric mucosa. Pre treatment of experimental sand rats with a certain amount of ethanol can cause damage to the gastric mucosal tissue, disrupt the gastric environment, and cause ecological imbalance of the gastric microbiota, thereby facilitating the colonization of Hp. The use of indomethacin increases the sensitivity of gastric mucosa to Hp after inoculation. Although indomethacin and Hp infection cause gastric mucosal damage through different mechanisms, they jointly damage certain important pathways, leading to increased permeability of gastric mucosal cells and exposing fragile gastric mucosa directly to the invasion of gastric acid and pepsin, greatly increasing the risk of gastric ulcer occurrence. The two have a synergistic and additive effect.