EGCG对大鼠放射性肺损伤的防治作用及机制探索

目的：研究表没食子儿茶素-3-没食子酸酯（EGCG）对大鼠放射性肺损伤的防治作用及相关机制。方法：用^60Co源γ射线单次照射SD大鼠全肺，构建放射性肺损伤模型，激素治疗组和EGCG治疗组大鼠分别给予地塞米松注射液和EGCG治疗；以肺系数、HE染色、Masson染色和肺组织羟脯氨酸（HYP）含量观察及评价EGCG对放射性肺炎及纤维化的改善情况；检测血清总超氧化物歧化酶（T—SOD）活力和丙二醛（MDA）含量；用Western印迹检测肺组织Nrf-2、HO-1、NQO-1的表达。结果：EGCG可明显减轻肺脏充血水肿，减低肺系数、肺组织HYP含量、肺泡炎及肺纤维化评分；EGCG可明显降低血清MDA水平，提高血清T—SOD活力，上调大鼠肺组织细胞Nrf-2、HO—1、NQO—1的表达水平。结论：EGCG能明显改善放射性肺损伤及纤维化病变，可能是通过Nrf2-ARE信号途径增加抗氧化酶表达，提高机体抗氧化能力而发挥治疗作用的。

Therapeutic Effect of Epigallocatechin-3-Gallate （EGCG） on Radia- tion-Induecd Lung Injury in Rats and Related Mechanisms Research

Objective： To study the therapeutic effects and related mechanisms of epigallocatechin-3-gallate （EGCG） on radiation induced lung injury in rats. Methods： 160 SD rats were assigned randomly to control group （received sham-irradiation, n=40）, model group（received irradiation on the thoraces with single fraction 22 gray γ rays from ^60Co, n=40）, dexamethasone group（received dexamethasone therapy in intratracheally injecting way after irradiation on the thoraces, n=40） and EGCG group（received EGCG therapy in intratracheally injecting way after irradiation on the thoraces, n=40）. Randomly chosen 6 rats from each group once were sacrificed at 15, 30, 60 and 120 days after irradiation. Observe and evaluate the ameliorating effect of EGCG on radiation pneumonitis and fibrosis by lung coefficient assessment, HE staining, Masson staining and HYP content determination. Examine the total SOD activity and MDA content in rats serum and assess the expression of NrF2, HO1 and NQO1 in rats lung tissue by Western blotting. Results： Compared with model rats, EGCG treatment obviously decreased lung coefficient（P〈0.05） and HYP content in lung tissue（P〈0.05）, significantly ameliorated congestion and edema of lung and alleviated pneumonitis and fibrosis of lung through pathological observation; EGCG could significantly reduce MDA content（P〈0.05）, raise total SOD activity（P〈0.05） in rats serum and upregulate the expression of Nrf-2, HO-1, NQO-1 of rats lung tissue. Conclusion： EGCG could alleviate radiation induced pneumonia and lung fibrosis in rats probably through reinforcement of Nrf2-ARE signal pathway and obliteration of oxygen radi- cals to reduce lung tissue injury.