动物造模,胃溃疡模型 z-bio 2022-01-13 506

　　Peptic ulcer refers to the damage to the gastrointestinal mucosa caused by the digestion of gastric digestive juice itself. Peptic ulcers can occur in any part of the gastrointestinal tract. Among them, the stomach and duodenum are more common. The so-called gastric ulcer and duodenal ulcer are basically similar in etiology, clinical symptoms and treatment, and the diagnosis can be confirmed mainly through gastroscopy. Gastric ulcer is the most common disease of peptic ulcer. The development of gastric ulcer is mainly related to the imbalance between gastroduodenal mucosal damage factors and mucosal self-defense and repair factors. Helicobacter pylori infection, non-steroidal anti-inflammatory drugs (aspirin) and abnormal gastric acid secretion are common causes of ulcers. Gastric ulcers mainly occur in the corners of the stomach and small bends in the sinuses. Gastric acid and pepsin are very important digestive juices in gastric juice. Stomach acid is a strong acid substance with strong corrosiveness. Pepsin has the ability to hydrolyze proteins and can destroy the proteins in the stomach wall. However, even with these aggressive factors, the gastrointestinal tract can resist and maintain the integrity of the mucosa and its own functions. The main reason is that the mucosa of the stomach and duodenum also has a series of defense and repair mechanisms. Under normal circumstances, the protective mechanism of the gastric and duodenal mucosa is sufficient to resist the erosion of gastric acid and pepsin. However, when certain factors destroy certain links in the protective mechanism, gastric acid and proteases will erode the mucosa and form ulcers. If gastric acid is secreted too much, far exceeding the protective and repairing effects of the mucous membrane, it will cause ulcers. Recent studies have shown that Helicobacter pylori and non-steroidal anti-inflammatory drugs are one of the most common causes of ulcers, which can damage the protective mechanism of the gastrointestinal tract. Gastric acid plays a very important role in the formation of ulcers. In addition, drugs, stress and hormones can also cause ulcers. A typical active gastric ulcer is usually divided into four layers: the first layer is acute inflammatory exudate composed of necrotic cells, tissue fragments and fibrin-like substances; the second layer is the main beneficial middle layer and the third layer is granulation The tissue contains layers of proliferated capillaries, inflammatory cells and various components of connective tissue. The fourth layer is the fiber or scar tissue layer, which extends to the muscle layer and can even reach the necrotic layer. The typical four-layer ulcer structure is usually not observed, because endoscopic biopsy can only reach the mucosal layer or submucosa. Histopathology is mainly manifested by the infiltration of inflammatory cells in the mucosal layer. There are lymphocytes and neutrophils. Based on the internal inflammation of the cell or the formation of granuloma. The symptoms of gastric ulcers are usually atypical and may manifest as abdominal pain or discomfort. Most of them have various symptoms of indigestion, but some symptoms are asymptomatic before complications occur. Common complications include bleeding, perforation, and obstruction of the pile. With the development of human society such as cancer, competition has become increasingly fierce. Due to the influence of various high-pressure factors, the proportion of people suffering from gastric ulcers is also increasing. Challenge us before solving and treating gastric ulcer disease. More and more people hope to study animal models of human digestive system diseases to determine the cause and improve the cure rate of the disease. Since the nutrient absorption and gastrointestinal structure of miniature pigs are similar to humans, the gastric ulcer model made from miniature pigs has unique advantages over other animal models. Porcine gastric ulcer models can be divided into two categories: spontaneous and induced.

　　1. Spontaneous gastric ulcer model. Spontaneous gastric ulcer is mainly caused by abnormally excessive gastric acid and pepsin secreted into the stomach, causing the ulcer phenomenon caused by the destruction of gastric mucosa. Spontaneous gastric ulcers in pigs are usually caused by infectious gastroenteritis and classic swine fever virus disease. With the development of the large-scale pig industry, the number of cases of gastric ulcer in pigs has increased rapidly, and many model animals suitable for the study of gastric ulcer in pigs have also been provided. Since pigs are monogastric omnivores, multiple gastric ulcers are similar to humans and are in good condition as human gastric ulcer disease models, providing an excellent model for human gastric ulcer disease research. Miniature piglets can develop spontaneous gastric ulcer models from weaning to adulthood, and their clinical symptoms and pathological characteristics after the onset are similar to those of humans. The prone site is the gastroesophagus, and its symptoms are similar to the clinical symptoms of gastric ulcers in many people. Both pigs and humans are omnivorous animals with one stomach. The structure, eating habits and physiological characteristics of the gastric mucosa are very similar to humans, making them a good animal model for human gastric ulcers. The lower esophageal sphincter of pigs is regulated by nerve and humoral factors. Human reflux esophagitis (esophageal ulcer) is affected by gastrointestinal hormones, especially gastrin. When pigs suffer from gastroesophageal ulcers, the meat extract load test shows that the secretion of gastrin is reduced. This can also be seen from this point. This is similar to clinical symptoms. Human stomach ulcer. Stomach injury mainly occurs around the esophagus around the card gate. It does not secrete gastric acid and rarely occurs where gastric acid is secreted. The epithelial changes of the lesion are usually hyperkeratosis, diffuse ulcers, perforated ulcers or ulcers, which still leave scars after healing, and are distributed longitudinally along the esophageal mucosa, forming large radial folds and spreading, not only the lamina propria papillary papillae Damage and blood oozing. The focal plane fuses outwards, but it will not only melt and expand, but also penetrate deep into the muscularis mucosa, eventually forming an ulcer. The ulcer is oval, crescent or crescent, some of which occur only around the esophagus or spread throughout the esophagus. When the ulcer becomes chronic, part of the stomach tissue collapses during the necrosis of the ulcer, and the active part of the ulcer begins to fibrosis. The level of necrosis of the stomach wall develops and passes simultaneously. It penetrates the muscle layer vertically and develops directly to the subserosal membrane, causing peritonitis. Most ulcers on the fundus of the stomach are confined to the flat areas between mucosal ridges or mucosal folds. The width of the lesion is about 0.2-0.5cm, and the length is about 4-7cm. Histological observation, acute gastric ulcer, the epithelial cells of the gastroesophagus around the card gate are swollen, enlarged, irregular, and the degree of epithelial keratinization is inconsistent. The lamina propria swells due to inflammation and bleeding. The nipple collapses or bulges deeply, reaching the lamina propria. The lamina propria has infiltration of inflammatory cells. Congestion, swelling or bleeding at the edges of ulcerative necrotic tissue. Pathogenic microorganisms attack the base and surface of the ulcer covered by the fibrous necrotic membrane. Subacute gastric ulcers are associated with hyperplastic sclerosis of connective tissue, in which living cells slowly proliferate under the necrotic tissue lining the basal layer. Chronic gastric ulcer is a short-breathing mouth-like lesion with hard roots. The granulation tissue is formed under the surface of the necrotic base and contains inflammatory cells. The granulation tissue is fixed on the ab, and the connective tissue shrinks at the edge of the ulcer.

　　2, induced gastric ulcer model

　　(1) Model of gastric ulcer induced by glacial acetic acid: In recent years, researchers have found that forced feeding of glacial acetic acid can successfully replicate the gastric ulcer model of miniature pigs. After 3 hours, 360ml/L of glacial acetic acid was used to show that the bulge of the stomach wall observed with the naked eye was a clear white-yellow severe avascular necrosis and severely damaged the lamina propria of the gastric ulcer tissue under the microscope. This indicates that the mucosal epithelial layer has completely disappeared in some areas, and the lamina propria is exposed. This method may be better. Reproduction of gastric ulcer model in miniature pigs. It provides an excellent research platform for further analysis of its pathological changes and reveals the cause of human gastric ulcer. ..

　　Example:

　　There are 4 farm-sized pigs in China, weighing 8.5-11.5 kg, male. Intraperitoneal injection of 2% sodium pentobarbital (1.5-2 ml/kg is equivalent to 30-40 mg/kg) for anesthesia. First, measure the length of the esophagus from the lower lip to the xiphoid process of the minipig, and insert a 12 Fr gastric catheter from the mouth until the esophagus exceeds 2-3 cm. Under anesthesia, the gastric tube passes through the esophagus and cannot be swallowed by the animal. The operator needs to move slowly to prevent damage to the esophagus due to cooperative resistance. To check whether it is inserted into the stomach after insertion, insert the other end of the stomach tube into the water and observe whether there are air bubbles in the water to eliminate the possibility of being inserted into the lungs. Then, using a 20 ml syringe, inject 15 ml of 95% ethanol, absolute ethanol or 36% glacial acetic acid (actually 10 ml enters the stomach and 5 ml enters the gastric tube) to damage the local ulcer. The experiment was divided into three groups: one piglet perfused with 95% ethanol, one piglet with absolute ethanol, and two piglets perfused with 36% glacial acetic acid. The material was collected 3 hours after injection. After the animal was euthanized, the stomach was excised by laparotomy, the inner wall of the stomach was opened along the curvature of the stomach, and a flaky ulcer surface that was significantly different from the surrounding normal stomach tissue (white powder) was formed. The red inflammatory changes in gastric tissue and normal gastric tissue were taken, fixed in absolute ethanol, embedded in paraffin, frozen section, stained with HE, observed and photographed under a conventional optical microscope. According to the experimental results, even if 95% ethanol is taken orally, the gastric mucosa near the pylorus is intact, the mucosa is light red, the surface is smooth, and the local area is slightly hyperemia, edema, and deep red. Microscopic examination showed that the epithelium of the gastric mucosa and gastric cavity was intact, but some epithelium was swollen and slightly damaged. After intragastric administration with absolute ethanol, the gastric mucosal folds near the pylorus were still intact, but compared with the 95% ethanol intragastric administration model, the depth and area of the dark red mucosa increased significantly. Microscopic examination revealed that the epithelium of the gastric mucosa was damaged and thinned, but a small amount of epithelial tissue remained, the gastric pit was shortened, and the surface of the ulcer was obviously damaged. After 36% glacial acetic acid was administered into the stomach, the stomach wall was elevated, and it was obviously white and yellow, indicating severe avascular necrosis. Microscopic examination showed that the mucosal epithelial layer of the tissue was severely damaged, the mucosal epithelial layer in some areas completely disappeared, and the lamina propria was exposed. One day after intragastric administration, the ulcer becomes more obvious, and the boundary of the ulcer surface is clearly visible. (2) Gastric ulcer model induced by anti-inflammatory drugs: Non-steroidal anti-inflammatory drugs, such as aspirin and indomethacin, as well as other drugs with anti-inflammatory, antipyretic and analgesic properties, are generally considered to destroy diabetes. Gastric mucosal barrier. It changes the permeability of cell membranes, affects mucosal blood flow and cell regeneration, and inhibits prostaglandins and other mechanisms that cause gastric damage. Oral high-dose aspirin to piglets can cause bleeding on the gastric mucosal surface of pigs, leading to severe gastric mucosal cell shedding. When it is administered to the stomach for a long time, changes such as gastric ulcers occur. (3) Helicobacter pylori-induced gastric ulcer model: Helicobacter pylori (Hp) was first isolated from the gastric mucosa and epithelial cells of patients with chronic gastritis. In 1990, the relationship between Hp and chronic gastritis and peptic ulcer was determined. Recent studies have shown that Hp is also closely related to the development of gastric ulcer and gastric cancer. Helicobacter pylori infection is an important factor in the development of chronic gastritis and peptic ulcer. Urease, phospholipase, lipase and glycosylsulfatase produced by Helicobacter pylori all have the effect of destroying gastric and duodenal mucosa. Barrier function. Modeling techniques are usually performed in two stages. The first stage is the Helicobacter pylori infection experiment. The strain used to establish the animal model of Hp infection is the Hp international standard strain sydneystrain1 (ss1). SS1 contains cytotoxic genes and vacuolar toxin genes. Solid or liquid media can be used, 50 mg/L defibrillated sheep blood and vancomycin 10 mg/L, polymyxin B2500 U/L, antibacterial synergist 5 mg/L, oxygen demand microenvironment (volume Fraction 5% O2, 8) Add% CO2 80% N2)) Incubate at 37°C for 72 hours. Animals are usually vaccinated orally, fasting for 12-14 hours before each infection, injecting 1.5 ml of bacterial solution into the gastric tube, eating 30 minutes later, infection once a week, a total of 6 infections. Identification of infected animals: collect gastric mucosal tissues, prepare pathological sections and mucosal smears, and separate and culture them. Under a Gram staining microscope, test the isolated Hp with three enzymes (urease, catalase and oxidase) to determine whether it is SS1. The second step is to continue after the pig is diagnosed as positive for Helicobacter pylori Infected with Helicobacter pylori, and confirmed gastric ulcer through gastroscopy, so as to establish an animal model of gastric ulcer in miniature pigs.

　　3. Acute peptic ulcer model This model usually uses pyloric ligation to establish an acute peptic ulcer model. The pyloric ligation of Shay et al. Establishing the gastric ulcer model established (1945) is a simple and effective method. The mechanism of action is mainly due to the accumulation of acidic gastric juice in the stomach, resulting in damage to the gastric mucosa. Pig gastric ulcer model. Used to find anti-ulcer drugs and study the mechanism of ulcers.