茶黄素对胸腺放射性损伤的防护作用

Protective effects of theaflavins on radiation injury of thymus

目的探讨茶黄素对小鼠胸腺放射性损伤的防护作用。方法 25只C57BL/6小鼠随机分为对照组、照射组、照射+25mg/kg茶黄素组、照射+50mg/kg茶黄素组、照射+100mg/kg茶黄素组。对照组小鼠给予0Gy照射,其余小鼠接受4Gy全身照射。照射后第14天取小鼠胸腺检测胸腺指数、胸腺细胞总数,以确定茶黄素的最佳给药剂量。另取32只C57BL/6小鼠,根据最佳给药剂量将其随机分为对照组、茶黄素组、照射组、照射+茶黄素组,照射组和照射+茶黄素组小鼠接受4Gy的全身照射。照射后第14天检测胸腺组织形态、CD4CD8 T细胞亚群和胸腺细胞活性氧(ROS)水平。结果受辐射小鼠胸腺有放射性损伤,表现为胸腺指数下降,胸腺细胞总数减少,胸腺组织形态改变,胸腺T细胞亚群改变及胸腺细胞ROS水平升高。与照射组相比,照射+50mg/kg茶黄素组小鼠胸腺指数和胸腺细胞总数升高(P<0.05),且照射+50mg/kg茶黄素组小鼠胸腺细胞总数高于照射+25mg/kg茶黄素组(P<0.05)。与照射组相比,照射+茶黄素组胸腺病理改变改善,胸腺CD4^+CD8^-、CD4^+CD8^+细胞比例升高,而CD4^-CD8^-细胞比例下降(P<0.05),胸腺细胞内ROS水平降低(P<0.05)。结论茶黄素对4Gy全身照射诱导的小鼠胸腺放射性损伤具有一定的保护作用。

Objective To investigate the protective effect of theaflavins on thymus injury caused by total body irradiation(TBI).Methods Twenty-five C57BL/6mice were randomly divided into5groups:control group,4Gy TBI group,4Gy TBI+25mg/kg theaflavins group,4Gy TBI+50mg/kg theaflavins group and4Gy TBI+100mg/kg theaflavins group.Thymus index and total number of thymocytes were detected at the14th d post-irradiation to determine the optimal dose of theaflavins.According to this optimal dose,32C57BL/6mice were randomly divided into4groups:control group,theaflavins group,4Gy TBI group and4Gy TBI+theaflavins group.Thymus histomorphology,CD4CD8T cell subsets,and reactive oxygen species(ROS)in thymocytes were examined at the14th d post-irradiation.Results The irradiated thymus exhibited decreased thymus index and total number of thymocytes(P<0.05),aberrant histomorphology and T cell subsets(P<0.05),and increased ROS level in thymocytes(P<0.05).Compared with4Gy TBI group,the thymus index and total number of thymocytes were significantly increased in4Gy TBI+50mg/kg theaflavins group(P<0.05).The total number of thymocytes was significantly higher in4Gy TBI+50mg/kg theaflavins group than that in4Gy TBI+25mg/kg theaflavins group(P<0.05).Therefore,50mg/kg theaflavins was chosen as the optimal dose for subsequent experiments.Moreover,the aberrant histomorphology of irradiated thymus was alleviated by theaflavins.A decline in the percentage of CD4-CD8-T cells and an elevation of CD4+CD8-and CD4+CD8+T cells were found in irradiated mice administered with theaflavins(P<0.05).Compared with4Gy TBI group,the ROS level was significantly decreased in4Gy TBI+theaflavins group(P<0.05).Conclusion Theaflavins exhibits a protective effect on radiation-induced thymus injury.