疾病动物模型,心肌病模型 z-bio 2023-01-16 916

　　(1) Breeding method (1) Doxorubicin 2.5 mg/kg body weight was intraperitoneally injected into Wistar rats weighing 170 to 200 g at two-week intervals three times a week, and then administered for another week. 6 injections. The total dose is 15 mg/kg body weight. Observe for 4 weeks after the last injection. The cardiac function index of normal rats and rats modeled for 4 weeks were monitored with a cardiac function ultrasound monitor. Measurement method: Rats were anesthetized with 12% chloral hydrate and fixed on the examination table. Measure the long axis cross section of the left ventricle and the height of the left ventricular muscle, and measure the M-shaped curve and the end of the left ventricle. Take the dilated inner diameter (LVEDD, mm), left ventricular end diastolic diameter (LVESD, mm), left ventricular end diastolic volume (LVEDV), left ventricular end diastolic volume (LVESV) and the average value, and then convert LVEF and LVFS to Simpsons method. The formula LVEF = [(LVEDV-LVESV)/LVEDV]×100, LVFS = [(LVEDD-LVESD)/LVEDD]×100 is used as an index of cardiac function parameters. In normal Wistar rats, the cardiac function parameters were measured as normal reference standards under the same conditions. In experimental rats that were dissected and died spontaneously, the heart was fixed in 10% formaldehyde solution for 48 hours or longer, embedded in paraffin, and 5 μm serial sections were prepared, HE stained, and pathological changes were observed with an optical microscope. I observed it.

　　Replication method (2) Japanese big-eared white rabbits, weighing 1.5 to 2.5 kg, aged 3 to 4 months, inject doxorubicin from the rabbit ear vein at a dose of 1 mg/kg each time, twice a week for 8 weeks . This amount is approximately equal to 320 mg/m2, and doxorubicin is diluted with normal saline (NS) to 1 mg/ml. In order to avoid doxorubicin interference with acute cardiac poisoning, the animals were sacrificed after modeling, and a part of myocardial tissue was collected for histological observation. (1) Echocardiographic measurement: The structure and function of the left heart of the experimental group were determined through the front chest wall. (2) Observation of cardiac morphology: The left ventricular myocardium was collected, fixed with 10% formaldehyde (formalin) solution, embedded in paraffin, sectioned at 5 μm, HE stained, and pathological changes were observed with an optical microscope.

　　(2) The model creation method is simple, convenient and easy to operate, and it is suitable for establishing cardiomyopathy models of small animals. However, the molecular mechanism of cardiomyopathy is still unclear, and there are many experimental evidences that it is related to free radicals. Superoxide cations and superoxide free radicals are produced by monoquinone metabolites that interact with iron ions, causing changes in the internal structure of myocardial cells. Various changes, such as the chronic loss of myocardial fibers and the formation of vacuoles in the myocardial cytoplasm. Because the chest wall of rats is thin and the heartbeat is fast (300-400 beats/min), traditional methods of detecting heart function (such as various catheters and Langondorf perfusion methods) are invasive. These methods are endpoint detection and hemodynamics. However, there are no results regarding ventricular volume and inner diameter. The rat and rabbit models use a fast, convenient, non-invasive, and more accurate method to monitor the heart function of small animals, and the results are consistent with the overall anatomy and pathology. However, it has some disadvantages. Excessive doxorubicin will increase the mortality of laboratory animals. If the dose of doxorubicin is too low, model replication will fail. Due to the differences in the cardiac function of rabbits, there are also certain differences between rabbits of the same strain, depending on the age and weight of the rabbits. Therefore, it is necessary to use pure rabbits for experiments, and the growth environment of rabbits is basically the same age and weight.

　　(3) Comparative medicine currently uses three main models in the study of cardiomyopathy, viral infection, drug-induced and right ventricular high-rate pacing. The cardiomyopathy model caused by viral infection is the most relevant clinically. For example, Coxsackie virus is directly related to myocarditis and dilated cardiomyopathy. However, it takes at least one year to establish a model, and the use of viruses will bring great risks. It is difficult to distinguish between myocarditis and cardiomyopathy, which is not feasible. Cardiomyopathy caused by rapid pacing of the right ventricle is clinically relevant, but the pacemaker should be connected to the anterior wall of the right ventricle. Because the rat heart is small, the operation is inconvenient, and the success rate is low, this method is not suitable. Doxorubicin is an anti-hematological tumor. Its main side effect is myocardial damage. Increasing the dose and time of the drug can lead to dilated cardiomyopathy. Pathology showed that myocardial cells were swollen and the gap became smaller. Significant changes in cardiac function such as myocardial fibers and vasodilation in myocardial interstitium, LVEF and LVFS are significantly reduced, LVDD and LVDV are reduced, and LVSD is increased. The pathological changes and changes in cardiac function are similar to clinical cardiomyopathy.