丙谷二肽对γ射线致小鼠肺组织损伤的防护作用

摘要

目的：探讨N（2）-L-丙氨酰-L-谷氨酰胺（丙谷二肽）对γ射线致小鼠肺组织损伤的防护作用及可能的作用机制。方法：将27只雄性昆明小鼠随机分为正常对照组、辐射组和丙谷二肽组，每组9只。丙谷二肽组按照1000 mg/kg的剂量灌胃给药，1次/d，连续7 d。然后辐射组、丙谷二肽组均给予4．0 Gy 60 Coγ射线照射3 d，正常对照组不作处理。照射后测定小鼠肺脏指数、肺组织超氧化物歧化酶（ SOD）活性，MTT法测定肺组织细胞增殖率， AnnexinV和PI双染法测定细胞凋亡率，Western blot法检测肺组织Bcl-2和Bax蛋白的表达。结果：3组小鼠肺脏指数、肺组织SOD活性、细胞凋亡率、肺组织Bcl-2和Bax蛋白表达水平差异均有统计学意义（ F＝6．352、51．459、462．790、74．434和675．500，P＜0．05）。与正常对照组相比，辐射组小鼠肺组织SOD活性下降，肺脏指数升高，细胞凋亡率增加，肺组织Bcl-2蛋白表达降低，Bax蛋白表达升高（P均＜0．05）。与辐射组比较，丙谷二肽组肺组织SOD活性显著升高，细胞凋亡率降低（P均＜0．05），细胞增殖率升高（t＝5．294，P＜0．05），Bcl-2/Bax比值显著提高（t＝218．920，P＜0．05）。结论：丙谷二肽对60Co γ射线辐射损伤小鼠肺组织具有一定的防护作用，这种保护作用可能与调控Bcl-2、Bax表达有关。%To investigate the possible mechanism involved in the protective effect of L-alanyl-L-glutamine ( Ala-Gln) against irradiation-injured lung tissue of mice .Methods:A total of 27 male Kunming mice were randomly assigned to control group , irradiated group and Ala-Gln-treated group ,9 in each group .Mice in the Ala-Gln-treated group were adminis-trated with 1 000 mg/kg Ala-Gln by gavage for 7 d.Then,the mice in irradiated group and Ala-Gln-treated group were irra-diated with 4.0 Gy 60Coγ-ray for 3 d.After irradiation, lung to body weight and superoxide dismutase (SOD) activity in lung tissue were detected;the proliferation and apoptosis were detected by MTT method and AnnexinV and PI staining ,re-spectively;the expressions of Bcl-2 and Bax proteins in lung tissue were detected by Western blot .Results: There were significant differences in lung to body weight ,SOD activity in lung tissue , apoptosis rate , and the expression levels of Bcl-2 and Bax proteins among the 3 groups(F=6.352,51.459,462.790,74.434 and 675.500,P<0.05).Compared with those of the control group , lung to body weight was higher , SOD activity was lower , apoptosis rate was higher , the Bcl-2 expression was lower and that of Bax protein was higher in irradiated group (P<0.05).Compared with those of the irradia-ted group, SOD activity in Ala-Gln-treated group increased, apoptosis rate decreased, and the proliferation rate and Bcl-2/Bax ratio were higher(t=5.294 and 218.920,P<0.05).Conclusion: Ala-Gln has radio-protective properties to lung in mice via modulating the expression levels of Bcl-2/Bax.