动物模型,骨质疏松 z-bo 2020-08-10 584

　　1 Ovariectomy model

　　(1) Reproduction method Female experimental rats were anesthetized by intraperitoneal injection of 2% sodium pentobarbital at a dose of 40 mg/kg body weight, a sterile lower abdomen was incised, the abdominal muscles were bluntly separated into the abdomen, and the ovaries were ligated with silk threads and removed. 10 million u of vancomycin was injected into the abdominal cavity before suture the incision. After modeling, the rats were reared routinely, and they were free to drink and eat.

　　(2) Model characteristics After ovariectomy, the plasma estrogen (E2) content of the model rats decreased significantly, the femoral midpoint cortical index also decreased significantly, and the bone mass and bone quality also decreased significantly. Microscopic histopathological observation showed that the bone trabecula was broken, sparsely arranged, and the integrity of the morphological structure was poor in the bone tissue slices.

　　(3) Comparative medicine Osteoporosis is one of the common diseases of the elderly in clinical practice. It is more common in women after menopause. With the prolongation of postmenopausal time, the incidence of osteoporosis in middle-aged and elderly women can increase significantly, indicating that ovarian secretion The estrogen has an important influence on the occurrence and development of osteoporosis. After ovariectomized rats, the secretion of estrogen in the rats is reduced, which weakens the inhibition of osteoclasts, bone resorption is greater than bone formation, bones are in a state of high turnover, bone mass cannot be balanced, and bone loss increases. Under the microscope, the area of trabecular bone decreased, the number decreased, and the degree of separation increased. Previous studies have shown that rats aged 3-9 months are suitable for replicating osteoporosis models, especially 6-month-old rats that have reached their peak bone mass. If the rat is too young, the bone loss will be masked by the ovariectomized bone due to the significant increase in the growth period; but after 12 months of age, the rat will begin to enter the aging stage, and there will be senile bone loss in the body, which will affect the experiment The results are observed. So far, the osteoporosis model replicated in ovariectomized rats is the best model recommended by WHO and the US FDA for studying postmenopausal osteoporosis.

　　2 Retinoic acid model

　　(1) Reproduction method 3-month-old female rats take retinoic acid orally at a dose of 70 mg/kg body weight every day for 14 days, and then change retinoic acid to normal saline for 14 days. Animals are raised on a regular basis, free to drink and eat. The animals were sacrificed on the 29th day after the start of model building, and their tibias were taken and fixed in fixative, routinely decalcified, embedded in paraffin, made serial sections, and observed under a light microscope.

　　(2) Characteristics of the model After 3 days of oral administration of retinoic acid, the food intake of the model rats was significantly reduced; on the 14th day, the weight of the animals was significantly reduced, their activities were reduced, and arched backs were seen. The bone mass and morphology of the cancellous bone (trabecular bone) near the heart of the tibia of the model rats changed significantly, the area percentage and density of the trabecular bone decreased significantly, and the trabecular bone space increased. The morphometric results of bone tissue slices in model animals showed that the percentage of compact bone area in the middle of the tibia was also significantly reduced, and the percentage of bone marrow cavity area was increased. The percentage of bone resorption perimeter of the endosteal surface reflecting the activity and function of osteoclasts was significantly increased. The model is simple and convenient to make, the model time is short, the model success rate is high, the animal osteoporosis is typical, and it is easy to carry out drug administration observation.

　　(3) Comparative Medicine Retinoic acid is a derivative of vitamin A, which has a pharmacological effect similar to that of vitamin A. It is mainly used clinically for the treatment of various dermatological diseases, but it is accompanied by osteoporosis side effects. Past studies have shown that retinoic acid can activate osteoclasts in the body to promote bone resorption, but has no inhibitory effect on osteoblast activity, and has no obvious effect on bone formation and the mineralization process of bone matrix. Bone resorption is greater than the negative balance of bone formation, leading to osteoporosis in animals. The pathological changes of the osteoporosis model established by this method are very typical. Microscopically, the trabecular bones are sparse, the bone cortex is thinned, and the bone marrow cavity is enlarged. However, due to its modeling mechanism, it can cause damage to the gonads of the model animal. Compensatory hypertrophy occurs in the spleen and adrenal glands, so their practicability is not as good as the osteoporosis model established by the ovariectomy method.

　　3 Cortisone model

　　(1) Reproduction method 3-month-old rats were orally administered hydrocortisone injection at a dose of 3.6 mg/kg body weight, 6 times a week, and changed to 2 times a week after 30 days. The total administration is 60 days. The rats were subcutaneously injected with 25 mg/kg body weight of tetracycline hydrochloride and 30 mg/kg body weight of Calein solution 10 days and 2 days before the animals were sacrificed to make them form fluorescent double markers on the bone surface to observe the dynamic changes of bone formation during the two injections.

　　(2) Characteristics of the model The body weight of the model rats was significantly reduced at the end of the administration. The microscopic observation of bone tissue slices showed that the trabecular bone area decreased, the trabecular bone space increased, the rate of mineralization deposition and the rate of bone formation decreased.

　　(3) Comparing the mechanism of medical replication of glucocorticoids in an animal model of osteoporosis. The main reason is that super-physiological doses of corticosteroids can inhibit the activity of osteoblasts in the body and reduce bone formation; it also causes the body's calcium: scale, vitamin D and Changes in parathyroid hormone metabolism promote bone resorption, leading to a negative balance of bone resorption greater than bone formation, resulting in bone loss and osteoporosis. This model is of positive significance for the study of secondary osteoporosis caused by human glucocorticoids.

　　In addition to the above three commonly used animal models of osteoporosis, there are also the following osteoporosis animal models for special research purposes. ①Detesticular rat model: 4 to 6-month-old male rats were detested, and the rats quickly developed low bone mass after the operation. The reason was that the animal could not reach the peak bone mass, not caused by androgen deficiency. The bone metabolism conversion rate of resected rats is increased, and osteoporosis mainly occurs in cancellous bone, but after androgen supplementation treatment, the osteoporotic lesions can be reversed. ② Brake osteoporosis model: Because the bone mass and bone metabolism of animal limbs are closely related to factors such as weight bearing, muscle stimulation, neurovascular nutrition to muscle and bone. Commonly used replication methods include mechanical fixation, suspension, and surgical removal of one side of the animal’s sciatic nerve or one side of the knee muscle or Achilles tendon. Because the mechanism of immobilization leading to osteoporosis is not exactly the same, the results of one immobilization model cannot be extrapolated to other models. After the braking factor is removed, bone mass can usually be restored, but it takes much longer than the modeling time. It is now advocated to study senile osteoporosis based on the immobilization model with ovariectomy or orchiectomy. The former simulates the reduction of physical activity in the elderly, while the latter simulates the osteoporosis caused by the decline of gonadal function.

　　Rats are the most commonly used experimental animals in human osteoporosis research, because ① Rats have obvious growth and adult periods, so it is easy to observe the effect of age on bone tissue. ②The anatomy of the skeletal system has many similarities with humans. ③The amount of cancellous bone in multiple parts of adult rats remained stable for a period of time, which is suitable for the study of cancellous bone reconstruction. ④Similar to human cancellous bone distribution and reconstruction function and lamellar bone trabecular bone reconstruction ability.