西咪替丁对低剂量^(60)Co γ射线照射小鼠肠道免疫组织的保护作用

Protective effect of cimetidine on intestinal immune system of low dose-irradiated mice

目的观察西咪替丁对低剂量电离辐射小鼠肠道免疫组织的保护作用。方法 60只雄性C57小鼠随机分为6组:正常对照组,照射模型组,阳性对照组以及西咪替丁低、中、高剂量(33.3、100、300mg/kg)组,每组10只。除正常对照组外,其他各组采用1.0Gy ^(60)Coγ射线全身照射,剂量率为8.33m Gy/min。西咪替丁各剂量组于照射前按设定剂量连续灌胃给药6d,每天1次,照射后5h再给药1次;阳性对照组于照射前、后各给药1次。照射后24h,检测小肠免疫组织病理变化、小肠黏膜免疫细胞凋亡情况、肠派伊尔结(PP)内淋巴细胞凋亡率和T、B淋巴细胞数量。结果1.0Gy照射后24h,小鼠小肠隐窝处可见淋巴细胞凋亡,肠PP内淋巴细胞凋亡率与正常对照组比较明显增加(P<0.01),CD3^+T细胞、CD19^+B细胞数量均明显下降(P<0.01,P<0.05)。与照射模型组比较,西咪替丁各剂量组小肠隐窝内淋巴细胞凋亡减少,肠PP内淋巴细胞凋亡率明显下降,T淋巴细胞数量明显上升,差异均有统计学意义;西咪替丁低、高剂量组B细胞数量明显增加(P<0.01)。结论西咪替丁可有效改善1.0Gy ^(60)Coγ射线照射小鼠肠道免疫功能,具有较好的辐射保护作用。

Objective To investigate the protective effect of cimetidine （CMD） on intestinal immune tissue of low- dose irradiated mice. Methods Sixty C57 male mice were divided into six groups： normal control group, radiation model group, positive control group and CMD groups （at the dose of 33.3, 100 or 300mg/kg）. The mice were irradiated with 1.0Gy 60Co γ-ray at 8.33mGy/min rate. CMD was given using oral gavage for 6 days before irradiation and at 5h after irradiation. At 24h after irradiation, histopathological changes of intestinal immune tissue, the apoptosis rate of lymphocytes and number of T and B lymphocytes in intestinal Peyer＇s patch （PP） were detected. Results At 24h after 1.0Gy γ-ray exposure, lymphocyte apoptosis was observed in the small intestinal crypt and the apoptosis rate of intestinal PP lymphocytes increased significantly （P〈0.01）. The number of CD3＋ T lymphocytes and CD19＋ B lymphocytes in intestinal PP decreased significantly （P〈0.01, P〈0.05）. Compared with model control group, the apoptosis rate of intestinal PP lymphocytes decreased （P〈0.01, P〈0.05）, while the number ofT lymphocytes increased in CMD groups （P〈0.01, P〈0.05）. The number ofB lymphocytes increased in 33.3mg/kg and 300mg/kg cimetidine groups （P〈0.01）. Conclusion CMD could improve the intestinal immune functions of mice irradiated by 1.0Gy 60Co γ-ray and has a protective effect on low-dose irradiated mice.