外源核苷酸对小鼠胸腺细胞凋亡的影响

目的 探讨外源核苷酸对小鼠胸腺细胞凋亡的影响。方法 首先建立了体内细胞凋亡模型,25只4周龄雄性小鼠腹腔注射地塞米松(25mg／kg)4、8、16、24h后取胸腺淋巴细胞进行细胞凋亡检测。确定建立体内细胞凋亡模型的条件为注射地塞米松(25mg／kg)后16h取小鼠胸腺细胞。外源核苷酸对小鼠胸腺淋巴细胞凋亡的影响,60只小鼠分成阴性对照、阳性对照、核苷酸1组、核苷酸2组,共4组,每组15只小鼠,均饲喂半纯合饲料。对照组每天灌胃生理盐水,核苷酸1组和2组分别灌胃12．5mg和25mg的核苷酸,连续饲养14d后阳性对照组和核苷酸组小鼠腹腔注射地塞米松溶液,诱导小鼠胸腺淋巴细胞凋亡,阴性对照组注射等量的生理盐水,16h后分离脾脏和胸腺,测定脾脏及胸腺指数,并采用琼脂糖凝胶电泳和流式分析方法检测胸腺淋巴细胞凋亡情况以及细胞游离Ca^2 浓度(Ca^2 ]i)。结果 核苷酸1组和2组小鼠的增重分别为3．71、4．01g,阴性对照组小鼠增重为2．74g,注射地塞米松后阳性对照组和核苷酸组小鼠的脾脏、胸腺重量以及脏器指数低于阴性对照,添加核苷酸对这些脏器指数没有明显影响;注射地塞米松后小鼠胸腺细胞DNA出现梯形条带,注射地塞米松后阳性对照组和核苷酸组小鼠胸腺细胞内Ca^2 水平分别升高至167．37nmoL／L、191．16nmol／L、180．78nmol／L,高于阴性对照(103．76nmoL／L)。细胞凋亡率也分别由阴性对照组的0．31％升高到11．93％、9．82％、11．15％,补充核苷酸对细胞内Ca^2 水平和细胞凋亡率均没有显著影响。结论 外源核苷酸对地塞米松诱导的小鼠胸腺细胞凋亡没有显著影响。

Effects of nucleotides on apoptosis of thymocytes

OBJECTIVE: To study the effects of nucleotides on apoptosis of thymocytes in mice. METHODS: Apoptosis model in vivo was first established and 25 KM mice, 4 weeks old, were randomly divided into 5 groups. One group was control, and the others were test groups. Mice in test groups were injected with DEX (25 mg/kg) and the controls were treated with normal saline. 4, 8, 16, and 24 hours later the thymus and spleen were weighed and lymphocytes in thymus were separated. The apoptosis of lymphocytes was analyzed by using DNA electrophoresis and flow cytometry. 16 hours later lymphocytes apoptosis reached a peak and lasted 24 hours. Methods used to establish apoptosis model in vivo were: mice (4 weeks old) were injected with DEX (25 mg/kg), and thymus lymphocytes were separated 16 hours later and analyzed. The effects of nucleotides on apoptosis of mice thymocytes were investigated in experiment 2. Sixty KM mice, 20 g +/- 2g, 4 weeks old, were divided into four treatments: negative control group (NC), positive control group (PC), nucleotides-additive group 1 (NTS1) and nucleotides-additive group 2 (NTS2). RESULTS: Body weight gained in NST1 and NST2 were 3.71 g, 4.01 g respectively, significantly higher than NC (2.74 g) (P < 0.01) and in NST2 was significantly higher than in PC (2.96 g) (P < 0.01). Thymus index and spleen index were decreased significantly (P < 0.01), and no difference was found with the supplementation of nucleotides (P > 0.05). Ca2+]i increased to 167.37 nmol/L, 191.16 nmol/L, 180.78 nmol/L in PC, NST1 and NST2 with DEX, being significantly higher than in NC (103.76 nmol/L) (P < 0.01). The percent of apoptosised thymocytes in groups were 0.31%, 11.93%, 9.82%, 11.15%, respectively. Thymus index and spleen index, cell apoptosis and Ca2+]i were not differed significantly among PC, NTS1 and NTS2 groups. CONCLUSION: Nucleotides should have no significant effects on apoptosis of thymocytes in mice in vivo.