动物造模,肝衰竭模型 z-bio 2021-03-24 817

　　(1) Replication method Adult mice are injected with paracetamol (APAP) at a dose of 900 mg/kg body weight, adult rats are injected with 500 mg/kg body weight of APAP in the same way, or adult experimental dogs can be dissolved with dimethyl APAP sulfoxide (DMSO) was injected subcutaneously at 0, 9 and 24 hours. The first dose is 750 mg/kg body weight, and the last two doses are 200 mg/kg body weight. After administering to mice or rats, continuously observe their overall conditions, record the time of death caused by toxic substances, and collect blood regularly for liver function tests, and remove the liver for histological morphological examination. After administration of the experimental dogs, in addition to observing the general conditions and recording the time of death, physiological indicators such as heart rhythm, heart rate, respiratory rate, and urine output at various time points were also detected, and blood was collected. Liver.. After the functional measurement, the death or artificial execution of the model animals are collected, and the liver, heart, lung, kidney and other organs and tissues are collected for pathological examination.

　　(2) Model characteristics After 7 hours of administration, the animal serum ALT, AST and TBIL increased significantly, PT prolonged, prothrombin activity (PA) decreased, and plasma main amino acid content decreased. . ) The increased content is significantly higher than the increased branched-chain amino acids (BCAA). The liver tissue shows extensive cell damage, the liver lobules show flaky or pontine necrosis, and the inflammatory cells are dense liver macrophages that spread and spread; 48 The hourly animal mortality rate is as high as 68.7%, of which the male mortality rate is 100%. When administered to male SD rats for 2 hours, total liver glutathione was reduced by 90%, and mitochondrial glutathione was reduced by 58%. The experimental dog was administered for 48 hours, and the success rate of the model was 63%. After modeling, the experimental dog became sleepy, activity and food intake decreased, sleep, ALT, AST, ALP, NH3, BUN, branched chain amino acid/aromatic amino acid ratio (BCAA /). AAA) Decrease and change GLU, TBIL and electrolytes insignificantly. Under the microscope, the liver tissue showed diffuse liver cell turbidity, spot necrosis, increased eosinophils, and flaky necrosis. Some liver cells showed unbalanced balance, increased eosinophils and steatosis. Part of the liver sine wave is expanded and congested, and there is a small amount of inflammatory cell infiltration in the portal vein, all of which die within 48 hours, and the average survival time is 36 hours (10-48 hours).

　　(3) Comparative medicine APAP is a commonly used antipyretic and analgesic. Overdose of drugs can easily cause liver toxicity, which is one of the common causes of acute liver failure at home and abroad. For animals of different species, the mechanism of acute liver failure caused by APAP is basically similar to that of humans. At a therapeutic level, about 60% of APAP is bound to glucuronic acid, while 35% is bound to sulfuric acid and excreted by the kidneys. The combination of a small amount of N-acetyl-benzoquinone imine (NAPQI) and glutathione (GSH) sulfhydryl (-SH) reaction is a mixed functional oxidase that will not cause obvious toxicity. Excess APAP will saturate the first two metabolic pathways and increase the production of NAPQI. The depletion of GSH in the liver acts on the cell structure, causing central necrosis of the liver lobules, leading to liver failure due to acute ALT elevation. Hepatocytes from different animals such as AST, long-term PT, hepatocyte necrosis, etc. are more sensitive to the toxic effects of APAP, so mice are the most sensitive, followed by dogs, rabbits and monkeys. Therefore, mice, rats, and dogs are commonly used as model copy objects of APAP. Induce liver failure. Copying the APAP-induced acute liver failure model requires all questions, including dosage, route of administration, choice of anesthesia, whether to add inducers and how to reduce the effect of extrahepatic toxicity on the model. Consider in advance. Although APAP has a dose-dependent toxic effect, the level of APAP in the blood is not proportional to the severity of liver dysfunction. Animals with smaller doses are difficult to induce acute liver failure, or the replication rate is too low and the dose is too high. For example, if the oral dose exceeds 1000 mg/kg body weight, the animal may be accompanied by hypoglycemia. Methemoglobinemia or pulmonary edema. He died shortly after an external illness. Therefore, multiple doses of small doses are the most commonly used modeling method. Under normal circumstances, animals will develop hypoglycemia after 15 hours of administration, which can be relieved by intravenous infusion of glucose. 15-20 hours after administration, ALT began to rise, liver necrosis began, TBIL increased, GLU decreased, albumin (ALB) decreased, PT prolonged, and liver smell appeared. Hepatic encephalopathy, hepatic coma and epilepsy gradually appear after 30-48 hours, and when ALT reaches its peak until death, pathological examination of liver tissue shows severe central lobular necrosis. In the process of copying the model, attention should also be paid to the selection and use of anesthetics. Some commonly used anesthetics can exacerbate the liver toxicity of APAP. Mainly thiopental sodium, pentobarbital sodium, barbiturate sodium, halothane and so on. In addition, there are reports that both glutathione synthase inhibitors (BSO) and APAP are used for modeling. In the experiment, Beagle dogs were slowly injected intravenously with BSO at a dose of 2 mmol/kg body weight to irreversibly inactivate glutathione synthase in the animal. Two hours later, 100 mg/kg body weight of APAP was injected intravenously, and a certain amount of APAP was given. The blood concentration of intravenous injection every hour is maintained at the level of 150-250 mg/L. After the depletion of liver cell GSH, the concentration of APAP metabolite NAPQI rises sharply, causing extensive hepatocyte necrosis, becoming an animal model of acute liver failure. After 30-48 hours, the model animal appears drowsiness, coma and death. The use of APAP to replicate animal models of acute liver failure has many advantages, such as a short model replication cycle, simple methods and low prices. However, many factors have been shown, such as many influencing factors of the model, high exotoxin and poor reproducibility. That's not the best choice.