不同鼠龄小鼠脾细胞对过氧化氢诱导DNA损伤的修复能力

摘要

Objective To study the DNA repair capacity of splenocytes from young and old mice after stressed by hydrogen peroxide ( H2O2 ). Methods S1 nuclease digestion test was used to compare the ratio of single strand DNA in splenocytes before and after DNA repair. Excision repair capacity was investigated by unscheduled DNA synthesis( UDS)after H2O2 treatmenL Results Ratio of single strand DNA for both young and old mice were increased after H2O2 treatment, however, more significant decrease in the single strand DNA ratio was observed for young splenocytes( 13.4％ )than that in old ones (6. 8％ )after DNA repair (P ＜0. 05 ). As data from UDS indicated, the highest CPM value was achieved at about 12 h after DNA repair for both group of mice, while the absolute repair level for old mice was only one third of young mice (P ＜ 0. 01 ). Conclusions Splenocytes from young and old mice demonstrate a similar sensitivity to H2O2 stress, but DNA repair capacity obviously is declined with increased age. H2O2 accelerates cell senescence by promoting the accumulation of DNA damage.%目的 观察青年鼠和老年鼠脾细胞对过氧化氢(H2O2)诱导DNA损伤的修复能力的差异.方法 通过S1核酸酶消化实验,对比分析两组小鼠脾细胞在H2O2刺激前后单链DNA的比例及修复程度.通过非程序性DNA合成(UDS)实验观察脾细胞在H2O2刺激后的切除修复水平.结果 两组小鼠脾细胞的单链DNA含量与处理前相比均有明显提高,但修复后,青年鼠单链DNA含量的下降比例(13.4%)显著大于老年鼠(6.8%)(P<0.05).UDS实验表明,两组小鼠均在DNA损伤大约12 h后达到修复高峰,但老年鼠的绝对修复水平大约只有青年鼠的1/3(P<0.01).结论 青年鼠和老年鼠脾细胞对H2O2刺激具有类似的敏感性,但DNA的修复能力随小鼠的增龄显著降低.H2O2通过加速DNA损伤的积累从而促进细胞衰老.