不同剂量模式照射对大鼠放射性肺损伤的影响

目的建立不同剂量分割模式照射的放射性肺损伤动物模型,初步探讨不同剂量分割模式照射对放射性肺损伤的差异。方法 Wistar大鼠90只随机分为小分次照射组(2 Gy/次,每周照射5次,共15次)、大分次照射组(10 Gy/次,每周照射1次,共3次)和对照组(不照射),用60Co-γ射线对大鼠右肺进行照射,于照射后第1,3,5,10,24周末取大鼠静脉血,采用ELISA测定血清中转化生长因子β1(TGF-β1)和肿瘤坏死因子α(TNF-α),并于各时间点处死大鼠取肺组织,进行HE染色观察肺组织损伤的病理变化。结果大分次照射组大鼠血清中TGF-β1含量从放疗后第1周开始,迅速呈线性增长,到第10周时血清中TGF-β1含量达峰值,第5周到24周均维持在一较高水平;而血清中TNF-α含量变化呈抛物线型态,即放疗后血清中TNF-α含量从第1周较低水平迅速升高,到第10周时达到峰值,此后迅速下降;小分次照射组在不同时间段血清TGF-β1、TNF-α较对照组有所升高,但升高的幅度明显小于大分次照射组;大鼠肺组织受照射后经历了一个从急性放射性肺炎到慢性肺纤维化的病理损伤过程,无论是急性放射性炎症还是放射性纤维化小分次照射组均较大分次照射组明显轻微。结论在接受相同剂量照射时,小分次照射组血清中TGF-β1、TNF-α含量升高幅度明显低于大分次照射组,且大鼠肺组织病理损伤的程度明显较大分次照射组轻,因而小分次照射对晚反应组织具有良好的保护作用。

Impact of radiation-induced pulmonary injury in rats by different dose fractionation

Purpose To establish animal models of radiation-induced pulmonary injury by different dose fractionation,and to study the differences of radiation-induced lung injury in different dose fractionation.Methods Using male Wistar rats of SPF level,the right lungs of rats were radiated by 60Co γ-ray.Ninety Wistar rats were randomly divided into Low-dose fraction irradiation group,High-dose fraction irradiation group,and Control group.The TGF-β1 and TNF-α of serum in the 1st,3rd,5th,10th and 24th week after irradiation were measured by ELISA.The histological changes of their right lungs with HE staining from 1st week to 24th week after irradiation were observed.Results High-dose fraction irradiation group,TGF-β1 in serum increased after being radiated,and it reached a peak in 10th week.TGF-β1 in serum remained at high level from 5th week to 24th week.After being radiated,TNF-α in serum increased rapidly from 1st week and reached the peak in 10th week,then declined rapidly.Low-dose fraction irradiation group,TGF-β1,TNF-α in serum increased after irradiation,but the changes were less than that of High-dose fraction irradiation group.The pathological changes in pulmonary tissue had experienced a process from acute radiation-induced pneumonitis to chronic pulmonary fibrosis,including acute inflamma-tion period,hyperplasia period,and fibrosis period.Whether the acute radiation-induced pneumonitis or the radiation-induced pulmonary fibrosis,the Low-dose fraction irradiation group is lighter than the High-dose fraction irradiation group.Conclusion Received the same total doses of irradiation,Low-dose fraction irradiation group has less histological changes and the contents of TGF-β1,TNF-α in serum than High-dose fraction irradiation group,Low-dose fraction irradiation can protect late response tissue.