动物造模,肺纤维化,药效评价 z-bio 2024-06-14 424

　　1. Animal modeling materials: Healthy female Wistar rats, experimental grade II, with a weight of (220 ± 20) g; Instrument: 60Co gamma ray generator.

　　2. The modeling method involves total chest irradiation using 60Co gamma rays, with an irradiation field area of 4.5cm x 4.0cm. Align the position of the rat from the upper to the armpits and the lower to the sternum sword like process with this irradiation field, and use a 10cm thick lead brick screen to shield the remaining parts of the rat. The irradiation distance is 3m, the dose rate is 2.7Gy/min, and the dose is 30Gy.

　　3. Modeling principle: 60Co gamma rays cause pulmonary fibrosis in animals.

　　4. General changes after modeling: After a single dose of 30Gy full chest irradiation with 60Co gamma rays on adult female Wistar rats, hair loss and nasal bleeding were observed on the exposed skin of the animal's chest and back around the third week. After about a month, the depilation of the exposed skin on the chest and back becomes more pronounced, and eczema, erythema, erosion, and ulcers may occur on the skin in that area. Nasal bleeding is also more severe. After 3 months, the above symptoms improved, but nasal bleeding was still occasionally observed, and hair regrowth was observed after 6 months. At the same time as the above symptoms appear, the animal dies. Death can last from 3 weeks to 3.5 months after irradiation, but the peak of death is concentrated between 1.5-2 months after irradiation. The total mortality rate is 34.98%.

　　5. Pathological changes after modeling showed no significant abnormalities in the lungs and other parts of the rats 3-7 days after irradiation. 2-3 weeks after irradiation, scattered punctate or spotted bleeding was observed on the surface and section of the lungs. After 4 weeks of irradiation, a small or large amount of pale yellow or reddish yellow liquid was accumulated in the chest cavity, and the lungs were congested, bleeding, swollen. There was a large amount of foam like fluid flowing out of the cut surface, and the lung volume and weight increased. The ratio of lung weight to body weight is also significantly higher than that of normal control animals, reaching 3% and up to 4.9%. After 2 months of irradiation, the acute inflammatory changes in the lungs gradually decreased, and after 3 months, they significantly decreased. After 6 months, the lungs showed dense consolidation areas ranging from grayish yellow or grayish white mung bean size to broad bean size, especially in the left and right upper lobes of the lungs.

　　Light microscopy observation: The histological structure of the lungs in the control group rats is normal. The histological changes in the lungs of rats in the irradiation group initially showed acute inflammatory changes, but in the middle and later stages, they transformed into subacute or chronic progressive changes, which can be roughly divided into two stages and four stages. Early stage refers to the acute inflammatory or exudative phase, which mainly occurs within 2 months after irradiation. It is characterized by congestion of alveolar wall capillaries and peribronchial blood vessels, pulmonary hemorrhage, interstitial edema, and accumulation of red blood cells, macrophages, and alveolar epithelial cells in the alveolar cavity. The middle stage is the proliferative phase, which is often seen 2-3 months after irradiation. It is characterized by acute inflammation gradually subsiding and replaced by proliferative changes in cells, such as thickening of the alveolar wall, shrinking of the alveolar cavity, and an increase in the composition of alveolar wall cells, mainly fibroblasts. In addition, macrophages, lymphocytes, and other cells can also be seen. Extensive proliferation of fibroblasts can also be seen in the pulmonary interstitium around blood vessels and bronchi. In addition, there is a significant increase in lymphocytes in some parts of the stroma during this period. The above two stages are collectively referred to as the first stage of the disease, which is the radiation pneumonia stage. The third stage (later stage) is the fibrosis stage, which is more common at 3-9 months after irradiation. The main manifestation of this stage is severe thickening of the alveolar wall, significant reduction or disappearance of the alveolar cavity, and a significant increase in fibroblasts, especially fibroblasts, in the alveolar wall, bronchi, perivascular and other interstitial parts of the lung. Focal fibrosis occurs in these areas. The fourth stage (late stage) is the collagenization stage, which occurs 9-12 months after irradiation. During this period, the local lung tissue can be completely replaced by collagen tissue, and the alveolar cavity is extremely narrow or even disappears, with a decrease in the number of cells. The latter two stages together constitute the second stage of this disease, which is the progressive interstitial fibrosis stage.