外源核苷酸对免疫抑制小鼠胸腺细胞DNA损伤的影响

目的:检测外源核苷酸对经环磷酰胺诱导的免疫抑制小鼠胸腺细胞DNA损伤的影响。方法:采用18～20 g昆明种小鼠30只,雌雄各半,随机分成阴性对照组(NEC)、阳性对照组(POC)和核苷酸组(NTG),每组10只。NEC组和POC组小鼠均饲喂半纯合无核苷酸的基础日粮,NTG组则在基础日粮中添加0.25%的核苷酸,实验期为21 d。在实验结束前18 h POC组和NTG组小鼠按照150mg/kg bw的剂量腹腔注射环磷酰胺,NEC组注射生理盐水,实验结束时测定脾脏和胸腺脏器指数,并取胸腺细胞,做单细胞凝胶电泳,观察细胞DNA损伤情况。结果:在基础日粮中添加核苷酸对小鼠免疫器官重量没有显著影响(P>0.05),但能极显著降低受损胸腺细胞百分率(P<0.01)和受损细胞DNA尾长(P<0.01)。结论:外源核苷酸能显著降低免疫抑制小鼠受损胸腺细胞百分率和损伤程度。

EFFECT OF DIETARY NUCLEOTIDES ON DNA DAMAGE OF THYMOCYTES IN MICE

Objective: To study the effect of dietary nucleotides on DNA damage of thymocytes in mice. Methods: KM mice (n=30) , 5-6 weeks, were randomized into 3 groups,negative group (group 1), positive group (group 2) and nucleotides group (group 3). Mice in group 1 and 2 were fed nucleotide-free diet and group 3 nucleotide-supplemented diet (0.25% nucleotides). Mice in group 2, 3 were given single cyclophosphamide intraperitoneal injection of 150 mg/kg bw at day 21. DNA damage in thymus lymphocytes was evaluated 18 h after injection by single-cell gel electrophoresis (SCGE) assay. Thymus and spleen were weighed. Results: Dietary nucleotides had no effect on weights of thymus and spleen, but significantly decreased the number of damaged lymphocytes and the degree of damage. Conclusion: Dietary nucleotides may protect thymocytes DNA in mice from damage.