Objective To investigate the effect of ginsenoside Rg1 on the thymus structure and function of aging model rats and its relative mechanism.Mte hods 40 SD rats were randomly divided into normal control,Rg1 control,aging model and Rg1aging model groups .After 2 days of finishing injections,the thymus index was measured,paraffin section were made to observe thymus microscopic structure.Se-nescence-associatedβ-galactosidase ( SA-β-Gal) stain was used to detect aging thymocytes.The proliferative capacity of thymocytes stimula-ted with Concanavalin A ( Con A) was measured by CCK-8.The contents of TNF-α,GM-CSF,IL-2 and IL-6 were detected by ELISA.The apoptosis of thymocytes and level of reactive oxygen species( ROS) were analyzed by flow cytometry( FCM) .The content of malondialdehyde ( MDA)was detected by thiobarbituric acid method ,the level of superoxide dismutase (SOD ) was detected by enzymatic assay.The expres -sions of GSH,GSSG were detected by DTNB method.The expressions of senescence-associated protein P53,P21,Rb were detected by West-ern blot.Results Comparing with those of Rg1 aging model group,the thymus index,thymus cortex area proportion, the secretory capability of IL-2,TNF -α,GM-CSF,and IL-6,the active content of SOD were obviously increased.The percentage of SA-β-Gal positive thymocytes,ap-optosis rate of thymocytes,the production of ROS,MDA were significantly decreased,the expressions of P53,P21,Rb were also significantly down-regulated.Conclusions The thymus structure and function are obviously induced senescence by treating with D-galactose,ginsenoside Rg1 has a significantly antiaging or protective effect on thymus injury.The mechanism may be Rg1 inhibiting oxidative stress and down-regu-lating p53/p21/Rb signaling pathway.%目的：探讨人参皂苷Rg1对衰老大鼠胸腺结构与功能的影响及机制。方法 SD大鼠随机分为4组，每组10只。衰老模型组，皮下注射D-半乳糖120 mg／kg，1次／d，42 d；Rg1衰老模型组，注射D-半乳糖剂量与时间同衰老模型组，第15天起腹腔注射Rg120 mgk／g ，1次／d，28 d正常对照组，皮下注射生理盐水1次／d，42 d；R1g 正常对照组，注射生理盐水1次／d，14 d，第15天起腹腔注射Rg1（同Rg1衰老模型组）。模型复制或药物注射完成后第2天，取胸腺测定胸腺指数，石蜡切片观察胸腺形态学；衰老相关β-半乳糖苷酶（ SA-β-Gal）染色检测胸腺细胞衰老，CCK-8检测胸腺细胞对刀豆蛋白A刺激的增殖能力， ELISA检测胸腺细胞分泌肿瘤坏死因子（TNF）-α、GM-CSF、白细胞介素（IL）-2与 IL-6的能力，流式细胞术检测细胞活性氧（ROS ）、胸腺细胞凋亡，硫代巴比妥酸法检测丙二醛（ MDA），酶学检测超氧化物歧化酶（ SOD）， DTNB法测定谷胱甘肽（ GSH）、氧化谷胱甘肽（ GSSG）含量，Western 印迹检测细胞衰老相关蛋白p21、p53、Rb的变化。结果 Rg1衰老模型组大鼠胸腺指数升高、胸腺皮质面积比例增加、胸腺细胞的增殖能力提高，凋亡率减少、SA-β-Gal阳性胸腺细胞百分率下降、TNF-α、GM-CSF、IL-2、IL-6的分泌能力明显提高、SOD 活性明显提升；ROS和MDA含量下降；p53、p21、Rb 蛋白表达有显著下调。结论 D-半乳糖复制的衰老模型大鼠胸腺结构与功能损伤明显，人参皂苷 Rg1对其致衰损伤有明确的保护作用，其机制可能与抑制氧化损伤和下调1p6-Rb、p53／p21信号通路有关。
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