动物模型 z-bo 2020-08-10 658

　　Disseminated intravascular coagulation (DIC) is a clinically acquired syndrome, which can be caused by various reasons. Clinically, DIC is mainly manifested as multiple organ dysfunction, bleeding, shock and microangiopathic hemolytic anemia caused by microvascular thrombosis and embolism. DIC represents a series of serious clinical pathological manifestations. Its main feature is the progressive loss of its limitations or compensatory control after the activation of the intravascular coagulation mechanism. The occurrence and development mechanism of DIC is very complicated, and many influencing factors have not yet been fully elucidated. Regardless of the primary disease or the induction of DIC, the activation of the body's coagulation system has the characteristics of a sequential cascade reaction, as well as the characteristics of positive and negative feedback that amplify or limit the coagulation reaction. DIC usually shows that fibrin is distributed in various organs, which is the cause of organ failure. Anticoagulation therapy is one of the important measures to block the pathological process of DIC. Its purpose is to inhibit the pathological process of extensive microthrombosis and prevent further consumption of platelets and various coagulation factors. Create conditions for restoring its normal content and restoring normal blood coagulation and anticoagulation balance. Therefore, it is very important to establish an ideal DIC animal model for experimental research.

　　1 A rat model of diffuse intravascular coagulation induced by polymer dextran

　　(1) Reproduction method Male Wistar rats weighing 250 to 400 g, 10 months old. Anesthetized by intraperitoneal injection of sodium pentobarbital at a dose of 30 mg/kg body weight, the rats were fixed on the operating table supine, and the neck skin was routinely disinfected and depilated. The carotid artery and vein were exposed by aseptic surgery and cannulated separately. With 130g/L polymer dextran (molecular weight 480000) at a dose of 15ml/kg body weight through the jugular vein injection, 1min or 3min. Observe the microcirculation at 10 min before administration and 10, 20, and 30 min after administration, observe the flow state and micro blood flow of the mesenteric vessels in the lower ileum (including the first and second arterioles and the first and second venules) by microscopic television video Blood cell aggregation; 30 minutes after administration, blood was taken from the carotid artery of the model rat for detection of related coagulation function indexes, and the plasma protamine paracoagulation test (3R test) was performed; the main observation index: model rat micro Circulation integral value, whole blood viscosity, plasma viscosity, relative viscosity, platelet adhesion rate and aggregation rate, platelet count, plasma prothrombin time, fibrinogen level, and schizophrenia examination. Rats were anesthetized and killed 30 minutes after injection, and their lungs, kidneys, heart and other tissues were fixed with 10% formaldehyde solution for routine tissue sectioning, HE staining, and morphological observation under light microscope.

　　(2) Characteristics of the model Model animals have prominent changes in microvascular fluidity. After injection of polymer dextran, the flow rate slows down, blood cells are stagnated and aggregated, and the microblood flow appears to be slow, and severe microcirculation disorders appear. Using Tianniu’s microcirculation weighted integration standard to calculate the fluid state integral value, it was found that the fluid state integral value of model rats was significantly higher than that of pre-experiment and normal control animals, and these changes in arterioles were more obvious than fine veins. After modeling, the platelet adhesion rate and aggregation rate of the model animals were significantly increased, the platelet count was significantly reduced, the prothrombin time was prolonged, and the fibrinogen was decreased. There were significant differences compared with normal animals; the 3R tests of model animals were all positive. Histopathological observations under the microscope showed that fibrous thrombus and mixed thrombus were seen in model rats, especially in the lungs, and a large number of schistosome cells were seen in blood smears. The rat DIC model replicated by this method belongs to the acute type, which is characterized by reduced consumption of coagulation factors, hyperactivity of the secondary fibrinolytic system, obvious obstacles in hemorheology and microcirculation. The model making method is simple, the application range is wide, and the effect is stable.

　　(3) Comparative medicine. The pathogenic mechanism of this model is that after intravenous injection of macromolecular dextran, the micro blood flow integral value of model rats increases and blood flow slows down; abnormal blood fluidity leads to the body's vasomotor function Disorders create conditions for the occurrence of DIC. At this time, regardless of vasoconstriction, blood flow reduction, vasodilation, blood flow stasis, it is not conducive to the local removal of procoagulant substances and activated coagulation factors, but is beneficial to fibronectin (FN ) Settle locally. In addition, the blood viscosity, plasma viscosity, platelet adhesion and aggregation of the model animals were significantly increased after injection of polymer dextran, resulting in abnormal hemodynamics. Since abnormal hemodynamics is closely related to changes in blood flow resistance, when blood viscosity increases, blood flow resistance increases significantly. The most direct result is obvious obstacles to microcirculation, resulting in damage to tissue cells including endothelial cells, and then Aggravate the microcirculation disorder, such a vicious circle promotes the development of DIC in model animals. The disease characteristics of this model are similar to the DIC of clinical patients, and it is suitable for experimental research on DIC drug treatment and drug screening.

　　2 Lipopolysaccharide-induced diffuse intravascular coagulation model in rabbits

　　(1) Reproduction method Male New Zealand rabbits weighing about 2kg are anesthetized with sodium pentobarbital via ear vein at a dose of 30mg/kg body weight. After anesthesia, the rabbits are fixed supine on the operating table, and the neck skin is routinely disinfected and dehaired . An incision was made in the middle of the neck aseptic operation, the left common carotid artery was bluntly separated, the distal end of the artery was ligated, and an 18G intravenous cannula needle was used to puncture and fix it in preparation for specimen collection. The lipopolysaccharide was slowly injected into the rabbit ear vein at a dose of 2.5 mg/kg body weight, and the lipopolysaccharide was administered in 2 injections with an interval of 1 hour. The injection time of each lipopolysaccharide was about 10 minutes. Rabbit blood was taken before injection of lipopolysaccharide and 2, 4, and 6 hours after injection, respectively, for detection of activated partial thromboplastin time (APTT), fibrinogen, platelet count, antithrombin Ⅲ, and serum fibrin degradation products (FDP). At the end of the modeling, the animals were anesthetized to death, and the heart, lung, kidney, spleen and liver tissues were taken, fixed with 10% formaldehyde solution, and made conventional tissue sections, stained with HE, and observed under a light microscope.

　　(2) Model characteristics After the injection of lipopolysaccharide, the activated partial thromboplastin time of the model rabbits was significantly prolonged, the platelet count and fibrinogen were significantly reduced, the antithrombin Ⅲ activity was significantly decreased, and the serum FDP did not change significantly. Microscopic histopathological observations showed that microthrombosis could be seen in the heart, liver, lung, kidney, and spleen of the model rabbits, and a large number of inflammatory cells infiltrated in the lung tissue.

　　(3) Comparative Medicine DIC is a diffuse and hidden intravascular blood coagulation phenomenon, which can cause the body's blood coagulation factors to be continuously consumed, and clinically can cause extensive bleeding in patients. In the process of making this model, when there was blood oozing at the venipuncture site of the rabbit after lipopolysaccharide injection, the animal showed a significant increase in respiratory rate, cyanosis, a progressive decrease in the number of platelets, and a significant prolongation of APTT; There were fibrin thrombosis in lung, liver, kidney, and spleen tissues, which proved that intravenous injection of lipopolysaccharide can successfully replicate the rabbit DIC model. However, the blood FDP of the model animals did not change significantly, indicating that the DIC caused by lipopolysaccharide was mainly consumptive coagulation, and the fibrinolytic activity did not change much. At the same time, the APTT of the model animals was significantly prolonged after 2, 4, and 6 hours after the lipopolysaccharide injection, suggesting that the lipopolysaccharide In the process of inducing DIC, the body's endogenous coagulation pathway is activated. At this time, the body can generate thrombin through exogenous and endogenous pathways. The latter has a wide range of procoagulant and thrombosis effects. The DIC model replicated by this method shows that fibrin is distributed in multiple organs, which can lead to multiple organ failure in model animals. The performance of the model DIC is similar to that of clinical human DIC, and it can be used for experimental research on DIC pathogenesis and drug screening.