Preliminary Study On The Protective Effects Of Total Flavonoids Of Astragalus In Mice With Acute Radiation Pneumonitis

Objective: To explore the protective effect of flavonoids of Astragalus on radiation pneumonitis in mice according to the mechanism of radiation pneumonitis.Methods: The 48 healthy BALC/c mice were randomly divided into A (simple drug group), B (irradiation group), C (irradiation-drug group), D (control group). Mice in B, C group received 10Gy chest irradiation, while mice in A, D group were given simulated irradiation. After irradiation, A, C group were injected flavonoids solution through vena caudalis twice a week, the dose is 0.1ml; D group received normal saline as control.In 1w, 2w, 3w, 4w, 5w, 6w, 8w after irradiation , one or two mice from each group were killed under anesthesia and specimens of blood were centrifuged to obtain serum in 4℃which collected through digging eye method. Lung tissue were fixed with formalin.Results:1,pathology of lung tissueHE-stained glass smear: Inflammatory changes in lung tissue appears in one week after exposure. In group B (irradiation group) and C (irradiation-drug group), the alveolar walls and alveolar interstitial thickened, congested, even a part of the alveolar were closed through light microscope., larger amount of macrophages and neutrophil infiltration, interstitial edema appeared under high-power field, the main lesions were oozing. Group B were more significant than group C. Group A (simple drug group) and group D (control group) remains no changes above.2,Immunohistochemical results:TGF-β: In group B, the fifth week after irradiation, swelling of the lung intervals widened and a lot of TGF-βpositive cells appeared in the lung parenchyma, so does a large number of fiber cells, especially in the perivascular area adjacent to the trachea . Protein expression were mainly in cytoplasm of alveolar epithelial cells, macrophages, bronchial epithelial cells, stromal cells, etc. the nucleolus of which mostly were blue. Group C illustrated weaker than group B. TNF-α: In group B, the third week after irradiation, TNF-αexpressed in the alveolar septa, the bronchial smooth muscle, vascular smooth muscle, vascular endothelium, perivascular. Protein expression were mainly in cytoplasm of alveolar epithelial cells, pulmonary interstitial macrophages. Most of the nucleolus were blue. Group C illustrated weaker than group B.3,Serum antioxidant indexSerum SOD level of control group were significantly lower than simple drug group(P =0.031), while significantly higher than that of the radiation group and the radiation-drug group(P < 0. 01; P =0.038). serum SOD level of simple drug group than that of the radiation group and the radiation-drug group(P < 0. 01; P < 0. 01).Conclusions1,Total flavonoids of Astragalus prepared in this study can increase the concentration of serum SOD, reduce the expression of cytokines in the irradiated mice with radiation pneumonitis. Biopsy confirmed inflammatory changes were less in lung tissue of drug group.2,This study indicated that total flavonoids of Astragalus may prevent the development of radiation pneumonitis in mice through antioxidant mechanisms and provide an important reference for further study of other mechanisms for radiation damage.