动物造模,药效评价,骨质疏松 z-bio 2024-08-27 610

　　1 Ovarian resection model

　　(1) Method of replication: Female experimental rats were anesthetized by intraperitoneal injection of 2% pentobarbital sodium at a dose of 40mg/kg body weight. A sterile midline incision was made in the lower abdomen, and the abdominal muscles were bluntly separated from the peritoneum before entering the abdomen. The ovaries were ligated with silk thread and removed. Inject 100000 units of vancomycin into the abdominal cavity before suturing the incision. After modeling, rats were kept in regular feeding, with free access to water and food.

　　(2) The characteristics of the model are that after ovariectomy, the plasma estrogen (E2) content in the model rats significantly decreased, the cortical index of the femur midpoint also significantly decreased, and bone mass and bone quality also significantly decreased. Microscopic histopathological observation showed that the bone trabeculae in the bone tissue slices were fractured, sparsely arranged, and had poor structural integrity.

　　(3) Comparative medicine osteoporosis is one of the common diseases among elderly people in clinical practice, and it is more common in postmenopausal women; With the extension of postmenopausal time, the incidence rate of osteoporosis in middle-aged and elderly women can increase significantly, indicating that estrogen secreted by the ovary has an important impact on the occurrence and development of osteoporosis. After ovariectomy, the secretion of estrogen in rats decreases, which weakens their inhibition of osteoclasts. Bone resorption is greater than bone formation, and the bones are in a high transition state. The bone mass cannot maintain balance, leading to increased bone loss. Under the microscope, it is manifested as a decrease in the area, quantity, and separation degree of bone trabeculae. Previous studies have shown that rats aged 3-9 months are suitable for replicating osteoporosis models, especially those aged 6 months who have reached peak bone mass. When rats are too young, the significant increase in bone mass during the growth phase can mask the loss of bone mass after ovariectomy; After 12 months of age, rats may experience age-related bone loss as they enter the aging phase, which can affect the observation of experimental results. So far, the osteoporosis model replicated using ovariectomized rats is recommended by WHO and the US FDA as the best model for studying postmenopausal osteoporosis.

　　2D formic acid model

　　(1) Method of replication: 3-month-old female rats were orally administered with retinoic acid at a dose of 70mg/kg body weight per day for 14 consecutive days, followed by 14 days of changing retinoic acid to physiological saline. Animals are regularly raised, with free access to water and food. On the 29th day after the start of modeling, the animals were euthanized, and their tibia was fixed in fixative. The tibia was decalcified and embedded in paraffin, and continuous sections were made for observation under a light microscope.

　　(2) After oral administration of retinoic acid for 3 days, the food intake of the model rats significantly decreased; By the 14th day, the animal's weight had significantly decreased, activity had decreased, and there were visible arch backed vertical hairs. The bone mass and morphology of the trabecular bone (trabecular bone) in the proximal segment of the tibia of model rats showed significant changes, with a significant decrease in trabecular area percentage and density, and an increase in trabecular gaps. The morphometric results of bone tissue slices from model animals showed a significant decrease in the percentage of dense bone area in the middle of the tibia, an increase in the percentage of bone marrow cavity area, and a significant increase in the percentage of bone resorption circumference on the inner surface of the bone, which reflects osteoclast activity and function. The method of making this model is simple, the modeling time is short, the success rate of the model 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, with pharmacological effects similar to vitamin A. It is mainly used in the treatment of various dermatological diseases in clinical practice, but it is accompanied by osteoporosis side effects. Previous 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 significant effect on bone formation and mineralization of bone matrix. Ultimately, it leads to a negative balance of bone resorption over bone formation in the body, resulting in osteoporosis in animals. The pathological changes in the osteoporosis model established by this method are very typical, manifested under the microscope as sparse bone trabeculae, thinning of bone cortex, and enlargement of bone marrow cavity; However, due to its modeling mechanism, it can cause damage to the gonads and compensatory hypertrophy of the spleen and adrenal glands in model animals, so its practicality in research is not as good as the osteoporosis model established by ovarian resection method.

　　3 cortisone models

　　(1) Method of replication: Three month old rats were orally administered hydrocortisone injection at a dose of 3.6mg/kg body weight, 6 times a week. After 30 days, the dosage was changed to twice a week. The total duration of administration was 60 days. Ten days and two days before animal sacrifice, rats were subcutaneously injected with 25mg/kg body weight of tetracycline hydrochloride and 30mg/kg body weight of Calein solution, respectively, to form fluorescent double labels on the bone surface and observe the dynamic changes in bone formation during the two injections.

　　(2) At the end of drug administration, the body weight of the model rats significantly decreased. Microscopic observation of bone tissue slices showed a decrease in trabecular area, an increase in trabecular gaps, and a decrease in mineralization deposition rate and bone formation rate.

　　(3) The mechanism of replicating animal models of osteoporosis with glucocorticoids in comparative medicine is mainly that super physiological doses of corticosteroids can inhibit the activity of osteoblasts in the body, reducing bone formation; Simultaneously causing changes in the metabolism of calcium, vitamin D, and parathyroid hormone in the body, promoting bone resorption, resulting in a negative balance between bone resorption and bone formation, leading to bone loss and inducing osteoporosis. This model has positive significance for studying secondary osteoporosis caused by human glucocorticoids.

　　In addition to the three commonly used osteoporosis animal models mentioned above, there are also several osteoporosis animal models for special research purposes Testicular removal rat model: Male rats aged 4-6 months were testicular removed, and postoperative low bone mass appeared quickly in the rats. The reason for this was that the animals could not reach peak bone mass, rather than being caused by androgen deficiency. Testicular removal rats had an increased rate of bone metabolism conversion, and osteoporosis mainly occurred in cancellous bone. However, after androgen supplementation treatment, osteoporosis lesions could be reversed Brake induced osteoporosis model: Due to the close relationship between bone mass and metabolism in animal limbs, as well as factors such as weight-bearing, muscle strength stimulation, and neurovascular nutrition of muscles and bones. Common replication methods include mechanical fixation, suspension, and surgical resection of one side of the sciatic nerve or one side of the knee muscle or Achilles tendon in animals. Due to the different mechanisms of osteoporosis caused by braking, the results of one braking model cannot be extrapolated to other models. After releasing the braking factor, bone mass can usually be restored, but it takes much longer than the molding time. It is now advocated to conduct research on elderly osteoporosis by adding ovarian or testicular removal on the basis of the braking model. The former simulates the reduction of physical activity in the elderly, while the latter simulates osteoporosis caused by gonadal dysfunction.

　　Rats are the most commonly used experimental animals in human osteoporosis research because they have a distinct growth and adulthood period, making it easier to observe the effects of age on bone tissue The anatomy of the skeletal system has many similarities with that of humans The trabecular bone mass in multiple parts of adult rats remains stable for a considerable period of time, making it suitable for research on trabecular bone reconstruction The distribution and reconstruction function of trabecular bone similar to humans, as well as the trabecular remodeling ability of lamellar bone.