多环芳烃对金属硫蛋白缺欠小鼠微核及红细胞的影响

目的：观察两种致癌性多环芳烃化合物二甲基苯蒽（DMBA）和苯并（a）芘（BaP）对小鼠髓多染红细胞微核发生和血液循环中红细胞数量的时相影响以及金属硫蛋白的可能拮抗作用。方法：选用雄性金属硫蛋白（MT）基因敲除的转基因小鼠[MT(-/-)]和野生型小鼠[MT( / )]。在DMBA和BaP各50mg/kg1次腹腔注射染毒后24、48、72和144h，观察动物骨髓多染红细胞中的微核细胞发生率和外周血液循环中红细胞数量的变化。结果：DMBA和BaP均能引起两种小鼠骨髓多染红细胞微核发生增加和外周血液循环中红细胞数量减少。DMBA诱导微核发生的高峰在48h。在同种小鼠内DMBA诱导的微核细胞发生率大于BaP。在DMBA染毒48和72h后MT（－／－）小鼠的微核细胞率明显大于MT（＋／＋）小鼠，而在BaP染毒后两种小鼠之间差异无显著性。在DMBA染毒24h后MT（－／－）小鼠的红细胞数比染毒前明显减少。结论：在该研究 条件下，缺乏MT的小鼠的骨髓多染红细胞微核更易被DMBA诱导和发生红细胞数量减少。提示MT具有一定保护DMBA所致遗传损伤和红细胞系统损伤的功能。

Effects of polycyclic aromatic hydrocarbons on micronucleus formation and erythrocytes in metallothionein knocked-out mice

Objective To study the effects of 7,12|dimethylbenz(a)athrancene(DMBA)and benzo(a)pyrene(BaP),two polycyclic aromatic hydrocarbons,on mice bone marrow micronucleated polychromatic erythrocytes(MNPE) and peripheral erythrocytes and the possible protective role of metallothionein(MT).Methods Male MT|gene|knocked mice [MT(-/-)] and wild|type mice [MT(+/+)] were given a single dose of 50 mg/kg body weight of DMBA or BaP by i.p.injection.Time course of changes in frequency of MNPE and amounts of peripheral erythrocytes were observed 24,48,72 and 144 h after exposure,respectively.Results The increase of MNPE and decrease of erythrocytes were seen after both DMBA and BaP treatment in both MT(-/-) and MT(+/+) mice.The peak of MNPE was 48 h after DMBA treatment.The MNPE in MT(-/-) was higher than MT(+/+) mice 48 and 72 h after DMBA treatment,while there were no significant difference after BaP treatment.Peripheral erythrocytes in MT(-/-) decreased significantly than that in control mice 24 h after DMBA treatment.Conclusion MT(-/-) mice are more susceptible to DMBA|induced MNPE and erythrocyte damage.These results indicate that MT plays a role in prevention against DMBA|induced genetic toxicity and erythrocyte system damage.