大鼠放射性肺损伤模型的建立与动态观察

Establishment of Irradiation Induced Lung Injury in Rats Model and Related Mechanism Research

目的:建立并鉴定大鼠放射性肺损伤模型,摸索大鼠放射性肺损伤的病理变化规律,阐明氧化应激在其发生发展过程中的作用。方法:采用60Co源22Gy单次照射SD大鼠全肺。分别于照射前、照后1天,7天,15天,21天,30天,60天,120天活杀大鼠,计算肺系数,右肺行HE染色、Masson染色及天狼猩红染色,观察肺组织病理变化并对大鼠肺泡炎及纤维化程度进行评分,免疫组化法检测肺组织α-SMA表达情况;左肺进行羟脯氨酸含量测定;血清测定MDA含量、总SOD活力和TGF-β1含量。结果:(1)大鼠肺脏于照后15天开始出现明显大体改变,病理学表现为间质性渗出性炎症并随时间延长逐渐加重,照后60天至120天肺脏塌陷,表面可见纤维化病灶,病理改变以肺间隔内细胞增生和胶原纤维沉积为主;(2)血清T-SOD活力照后1天至7天短暂增加后其活力持续降低;血清MDA含量和TGF-β1含量随时间时间延长逐渐增高;(3)照后60天肺组织α-SMA表达明显增加,至照后120天最为显著。结论:成功建立了大鼠放射性肺损伤模型并阐述了其病理变化规律;氧化应激参与了放射性肺损伤的病理过程,为其防治提供了实验基础和理论依据。

Objective： To establish and investigate rats model of radiation induced lung injury. Methods： Group-received irradiation on the thoraces with single fraction 22 gray γrays from 60Co, n=70. Randomly chosen 6 rats once were sacrificed at 1, 7, 15, 21, 30, 60 and 120 days after irradiation. Body and whole lung weight of rats were measured to calculate lung coefficient. Right lung were extracted to observe the pathological changes and collagen fiber deposition of lung tissue by HE, Masson and Sirius red staining. Left lung were extracted to measure Hydroxyprolin content of lung tissue. Serum was extracted from venous blood to measure MDA content, T-SOD activity and TGF-β1 level. Eighty male SD rats were assigned randomly to control group-received sham;irradiation, n=10 and treatment. Results： （1） Macro changes such as depilation of thoracic and back where was irradiated, dermal, swelling and congestion of lung appeared in 15 days after irradiation and got worse later. Lung collapse and punetiform or trabs focus of fibrosis appeared in 60 to 120 days after irradiation. Compared with the control group, the pathomorphism change of model rats in early stage-7 to 30 days after irradiation represent small vessels anapetia, widened interalveolar septum, effusion in alveoli of lung and inflammatory cell infltrafion. The pathological changes of model rats＇ lung in late stage-60 to 120 days after irradiation mainly represent cellular proliferation and collagen fiber deposition in lung parenchyma. （2） The total SOD activity in model rats serum increases transiently in 1 and 7 days after irradiation and the difference is significant compared with control group（P〈0.05）, while the total SOD activity in model rats serum after 7 days maintained low level （vs control group P 〉0.05）. The MDA content in model rats serum began to increase significantly in 1 day after irradiation （vs control group P=0.007） and the increase last to 120 days（vs control group P〈：0.001）. （3） The TGF-β1 content in model rats serum increased significantly in 15 days after irradiation（vs control group P〈0.05） and the increase last to the sequent times. Conclusion： A rats model of radiation induced lung injury was established successfully. Oxidative stress may play an important role in the progress of radiation induced lUng injury.