铁过量对大鼠淋巴细胞DNA损伤的影响

目的： 探讨不同剂量铁补充对大鼠淋巴细胞DNA损伤的影响。方法：SPF级6~7周龄雄性Wistar大鼠40只，按体质量随机分为4组，每组10只大鼠，即对照组、缺铁组、10倍铁剂量补充组、20倍铁剂量补充组，4组均采用隔日腹腔注射右旋糖酐铁，每次注射0.72 mL，每次注射含Fe2+分别为0.9、0.3、9和18 mg，连续注射6周。4组大鼠自由饮用去离子水，喂饲无铁饲料，于第6周末眼眶取血，使用血清铁试剂盒测定血清铁浓度，采用碱性单细胞凝胶电泳法测定大鼠外周血淋巴细胞DNA损伤状况。结果：缺铁组大鼠血清铁含量为53.54 μmol/L，明显低于正常对照组的77.62 μmol/L(P<0.01)，10倍和20倍铁剂量补充组大鼠血清平均铁含量分别达到104.77 μmol/L和205.30 μmol/L，显著高于对照组(P<0.01)。外周血淋巴细胞DNA本底损伤分析显示，缺铁组和正常对照组淋巴细胞DNA损伤总体水平分别为25.30 AU和21.13 AU，两组间差异无统计学意义(P>0.05)，10倍和20倍铁剂量补充组DNA自发损伤水平分别为对照组的3.9倍和8.0倍(82.80 AU和169.50 AU)，显著高于对照组(P<0.01)；然而H2O2与铁过量联合损伤分析显示，大鼠外周血淋巴细胞在10 μmol/L H2O2处理后，缺铁组大鼠DNA氧化损伤水平达到260.40 AU，与对照组(259.00 AU)相比差异无统计学意义(P>0.05)，而10倍和20倍铁剂量补充组分别为对照组的1.1倍和1.2倍(293.80 AU和308.88 AU)，均明显高于正常对照组(P<0.01)。结论：10倍、20倍铁剂量补充均可提高机体铁的营养状况或增加铁负荷水平；与正常铁摄入水平相比，铁缺乏未见DNA本底及H2O2联合损伤增加，而铁补充过量可引发机体外周血淋巴细胞DNA本底损伤增加及H2O2联合损伤加剧。

The effects of iron excess on lymphocyteDNA damage in rats

OBJECTIVE:To investigate the effects of different doses of iron supplementationon lymphocyte DNA damagein rats.METHODS:Forty male Wistar rats were randomly divided into control group,iron deficiency 2+group,10 times-iron as control group and 20 times-iron as control group, containing Fe 0.9,0.3,9 and 18 mg,respectively. All rats were treated with intraperitoneal injection of 0.72 mL iron dextran every other day and the entire study lasted for 6 weeks. The rats in the four groups were provided with deionized water and food without iron,both freely available. After 6 weeks,the level of serum iron was determined by spectrophotomety and the peripheral blood lymphocyte DNA damage was assessed using comet assay.RESULTS:The level of serum iron in the iron deficiency group (53.54μmol/L) was significantly lower than that of control group (77.62μmol/L)(P<0.01). In addition,the levels of serum iron in 10 times-iron (104.77μmol/L) and 20 times-iron groups (205.30μmol/L) were significantly higher than that of control group(P<0.01). DNA damageassessmentindicated that there was no difference between iron deficiency group (25.30 AU) and control group (21.13 AU)(P>0.05). Howeverthe DNA damage of 10 times-iron group (82.80 AU) and 20 times-iron group (169.50 AU) were significantly higher than control group (P<0.01) ,being 3.9 times and 8.0 times, respectively,as control group. The results of combined DNA damage induced by 10μmol/L H2O2 showed that there was no difference between iron deficiency(260.40 AU) group and control group (259.00 AU) (P>0.05). The combined DNA damage of 10 times-iron group (293.80 AU) and 20 times-iron group (308.88 AU) were higher significantly than control group(P<0.01),which were 1.1 times and 1.2 times,respectively,as control group.CONCLUSION:10 times and 20 times iron supplements could improve the iron nutritional status in body or increase the level of iron load. Iron deficiency could not increase the level ofusual DNA damage or combined DNA damage,but iron overload could increase the level of lymphocyte DNA damage andc ombined DNA damage.