动物模型,高尿酸血症 z-bo 2020-07-31 703

　　Hyperuricemia is caused by a variety of reasons, including excessive uric acid production and/or reduced renal uric acid excretion, leading to supersaturation of urate levels in the extracellular fluid. For men and postmenopausal women, if the blood uric acid level continues to be 420μmol/L (7.0 mg/dl), the premenopausal woman is 350μmol/L (5.8 mg/dl), which is called hyperuricemia. Is generally considered. Primary hyperuricemia is usually associated with obesity, hypertension, hyperlipidemia, coronary heart disease, etc., while secondary hyperuricemia is mainly caused by certain systemic diseases or drugs. I will. In recent years, due to the improvement of people's living standards, changes in eating habits and lifestyle changes, the prevalence of hyperuricemia has increased year by year. The focus on the treatment of hyperuricemia has received clinical attention. Therefore, when studying the treatment of hyperuricemia, choosing a scientific and reasonable animal model is an important topic.

　　[Modeling mechanism] Increasing the source of uric acid or reducing uric acid excretion will increase the serum uric acid concentration and establish a hyperuricemia model.

　　1. There are four common methods to establish a hyperuricemia model: uric acid intake increases the source of uric acid is divided into endogenous and exogenous. Endogenous uric acid accounts for about 80% of the human body. It is either synthesized by amino acids, nucleotides and other small molecules, or produced by nucleic acid catabolism; the source of uric acid is mainly found in food. It accounts for about 20% of direct intake. Foods rich in uric acid precursors and purines promote the production of uric acid. Commonly used drugs and foods mainly include xanthine, hypoxanthine, yeast and sardines. Ingesting a large amount of exogenous uric acid in a short period of time can significantly increase the uric acid in the blood.

　　2. Uric acid that inhibits uric acid excretion in the body is mainly removed from the kidneys, and when the kidneys inhibit uric acid excretion, the concentration of uric acid in the blood increases and hyperuricemia is formed. Commonly used drugs include adenine, niacin and ethambutol.

　　3. Inhibit the activity of uricase. Uricase catalyzes the oxidation of uric acid to hydrogen peroxide and allantoin. The presence of uricase in rodents commonly used in modeling is a major obstacle to the establishment of hyperuricemia models. Therefore, eliminating or inhibiting uricase activity is the key to modeling. Today, you can use chemicals or genetic engineering techniques to achieve your goals. The uracil inhibitor oxoxazine is a triazine compound whose structure is similar to the purine ring of uric acid, competitively binds to uricase, and partially inhibits uricase activity.

　　4. The transgenic model uses genetic engineering technology to delete the gene that produces uricase in animals, obtains mice with uricase deficiency, and creates a hyperuricemia model.

　　[Modeling method]

　　1. Feed male Sprague-Dawley rats with uric acid or uric acid precursor (200±20)g, and place them in different cages to adapt them to the environment for a week, and drink water and eat freely. Feed preparation: evenly mix dry yeast powder and adenine into rat pellets so that the contents of dry yeast powder and adenine reach 10% and 0.1%, respectively. Limit the intake of yeast and adenine to 10g/kg and 100mg/kg, and drink freely. 19 days after feeding the high-purine diet, the rats can stop using the high-purine diet and switch to a normal diet to observe natural recovery.

　　2. When the excretion of uric acid is inhibited, in the rat hyperuricemia model, the body weight of the male Wistar rat becomes (200±10) g. The dose of adenine was 100 mg/kg body weight, and 250 mg/kg body weight of ethambutol was given intragastrically every day for 7-21 days. The increase in the dose of adenine can increase the increase in uric acid, but the kidney damage is more obvious.

　　3. Uricase inhibitor method for male Sprague-Dawley rats, give 500 mg/kg hypoxanthine (prepared with 3% soluble starch), subcutaneous injection of Oxoxazine, a mixture of lanolin and paraffin (mass ratio 3:2) as Solvent. 100 mg/kg body weight.

　　4. Urate oxidase (Urate oxidase) gene knockout mice can develop hyperuricemia and nephropathy.

　　[Model Features] 1. After 7 days of supplementing uric acid or uric acid precursors of a high-purine diet, blood uric acid increased slightly. On day 12 and day 19, rats' serum uric acid, creatinine, and urea nitrogen increased significantly, and the kidney appeared to be similar to clinical gout nephropathy. Similar pathological changes. Under an optical microscope, the renal tubular cells were swollen, more uric acid crystals were deposited in the interstitial area of the renal tubules, and there were local lymphatic monocytes in the interstitium, which indicated that I had local fibrosis. After stopping the supply of high yeast and adenine, the levels of uric acid, creatinine and urea nitrogen in the animal's serum continued to increase, reaching a peak 15 days after stopping the supply of high purine, and decreasing at 24 days. Start. At the same time, the observed renal pathological changes were reduced. , The two are consistent. By the 52nd day, the levels of uric acid, creatinine and urea nitrogen in rats were significantly reduced, but they were still higher than those of normal rats, and it may take some time to fully recover kidney function. Therefore, within 2 months of modeling, the model can be used to observe the effectiveness of drugs in reducing blood uric acid and improving kidney function.

　　2. Inhibition of uric acid excretion in hyperuricemia model rats. Increasing the dose of adenine may increase the increase of uric acid, but the kidney damage is more obvious. Increasing the dose will easily kill the animal. Can cause. Some scholars use different combinations, such as xanthine and ethambutol.

　　3. At 3, 9 and 12 hours after modeling with the urease inhibitor method, the serum uric acid concentration of model rats was significantly higher than that of normal rats; 24 hours after modeling, serum urea nitrogen and creatinine levels were normal. It is significantly higher than this group. This method of high uric acid levels can be maintained for more than 12 hours, while there is obvious kidney damage, but no animal death.

　　4. Uric acid oxidase gene knockout mice Uric acid oxidase gene knockout mice develop hyperuricemia and nephropathy, but the mortality rate is higher. Before 4 weeks, more than 1/2 of the animals died. Due to the high mortality rate, the use of knockout mice is limited.

　　[Model evaluation and application] Feeding rats with yeast and adenine feed can create an ideal animal model of hyperuricemia nephropathy. It is innovative and provides more suitable experimental conditions for the research of gouty nephropathy. It can be used in clinical, new drug development and research on gouty nephropathy. Intraperitoneal injection of hyperuricemia drugs cannot maintain a short duration and form stable and continuous hyperuricemia. Although it can be used as a model for observing drug prevention, it does not help to observe the therapeutic effect of drugs on hyperuricemia and is related to clinical hyperuricemia. The causes of hyperuricemia are very different, and the causes of hyperuricemia cannot be further studied. Hypoxanthine 500 mg/kg and oxalic acid 100 mg/kg were selected to prepare a rat hyperuricemia model, which is characterized by rapid increase in serum uric acid level, long maintenance time, small organ damage and no animal deaths. finished. dose. Based on this dose, by further adjusting the dosage of the modeled drug, high uric acid levels can be maintained at long-term saturated concentrations, resulting in animal models of persistent hyperuricemia and gouty arthritis. It has been suggested that preparations can be made. Some scholars have found that the direct use of uric acid and the use of uricase inhibitors to inhibit the metabolism of uric acid and increase the uric acid in the blood are related to the clinical cause of primary hyperuricemia. I believe there is still a big gap. The use of ethambutol, niacin, etc. to inhibit uric acid excretion and increase the accumulation of uric acid in the body is also very different from clinical primary hyperuricemia.