城市河涌水对C57BL/6J小鼠生殖和发育的影响

Effect of city canal river water on reproduction and development of C57BL/6J female mice

前期研究发现广州市周边小型企业集中点和生活区下游河涌水样中存在较高浓度的AhR激活物污染.为考察河涌水中是否存在对生殖和发育产生影响的TCDD类似物,本研究以检出河涌水样激活物平均值标准品TCDD做阳性对照,C57BL/6J雌性小鼠为模型进行了三代生殖毒性实验,了解长期暴露对动物生殖和发育产生的毒性影响.成年雌性小鼠40只,随机分4组,每组10只,分别饮用自来水(正常对照Ⅰ组),2ng·L-1TCDD标准水样(阳性对照Ⅱ组),石井河涌水(Ⅲ组),芳村河涌水(Ⅳ组),连续三代繁殖,观察水样对小鼠生殖和发育的影响.生殖指标结果显示,处理组与正常对照Ⅰ组比较,Ⅱ、Ⅲ和Ⅳ组亲代(P0,P1和P2代)小鼠的交配和妊娠时间均显著延长(p<0.05);交配率,受孕率,妊娠率和生育率逐代下降,分别为交配率以Ⅱ和Ⅲ组的P2代显著(p<0.05);受孕率和生育率以Ⅱ组P2代显著(p<0.05),Ⅲ和Ⅳ组连续3代均显著降低(p<0.05);妊娠率以Ⅱ组、Ⅲ组P2代下降明显(p<0.05),Ⅳ组连续3代均下降明显(p<0.05).发育指标结果显示,处理组Ⅱ、Ⅲ和Ⅳ组子代小鼠出生D4和D21的存活率明显低于正常Ⅰ组,以Ⅱ、Ⅲ组F2和F3代,Ⅳ组F3代(p<0.05)的下降明显;子鼠出生数量下降,以Ⅳ组F3代明显(p<0.05);Ⅱ组、Ⅲ组和Ⅳ组F3代的D7、D14和D21的生长体重低于正常组(p<0.05).血清类固醇激素检测结果显示,亲代经产鼠Ⅱ、Ⅲ和Ⅳ组与正常Ⅰ组比较,血清雌二醇(E2)P0代降低显著(p<0.001);血清孕酮(PNG)Ⅱ组P0代,Ⅲ组P0、P1代和Ⅳ组亲3代显著高于正常Ⅰ组(p<0.05).子代处女鼠Ⅱ、Ⅲ和Ⅳ组F2和F3代促黄体激素(LH)下降显著(p<0.001).实验结果显示代表污染水的Ⅲ和Ⅳ组与TCDD阳性对照Ⅱ组水样所引起的重要母体生殖指标、子代发育指标以及雌性生殖激素水平的变化相似,强烈提示河涌水样中存在持久性有机污染物并具有与TCDD类似的生殖毒性,长期低剂量的接触将影响雌性小鼠的生殖和发育功能,值得引起注意.

Our previous studies found that drainage canal water in Guangzhou contained amounts of AhR-activating ligands,as determined from a yeast AhR reporter system.In this study,a three-generation experiment was conducted to assess the reproductive and developmental risks associated with these waters in C57BL/6J female mice.40 female mice were randomly divided into 4 groups.Animals in the groups were allowed to continuously freely drink tap water （groupⅠ）,2ng·L-1 TCDD which had equivelant TEQ of the water samples （groupⅡ）,sample water from Shijing River （groupⅢ） and sample water from Fangcun River （group Ⅳ）.P and F generation mice were observed for general reproductive and developmental toxicity.The results showed that the major reproductive indices that were affected include Mean Day of Mating and Gestation,both were delayed significantly（p0.05）in treated groups comparing with the groupⅠin maternity over three generation.Other indices also altered in treated groups included significantly decreased Mating Index of groupⅡin maternity third （P2） （p 0.05）,decreased Fertility and Fecundity Index of group Ⅲ and Ⅳ（p 0.05）over three maternity generation,and decreased Gestation Index（p 0.05）in group Ⅱ and Ⅲ of maternity third and group Ⅳ over three generations.With regard to the effected development index of filial generation,the Survivor Rate on day 4 and day 21decreased significantly（p 0.05） in group Ⅱand Ⅲ of generation F2 and F3 in group Ⅳ of generation F3.The pup Body Weight of treated group on day 7,day 14 and day 21 were lower（p 0.05）than control in generation F3.Drinking of sample waters and TCDD water significantly decreased estradiol in maternity generation P0 （p 0.001） comparing with control.Also decreased were pregesterone in groupⅡ,Ⅲand Ⅳ（p 0.05）in filial generation F2 and F3,and the LH level（p0.001）.The most effected reproductive indices,development indices and reproduction hormanes between water samples and 2ng·L-1 TCDD water were very similar,implying that the city canal river water contained dioxin-like substances and may exert chronic toxic effect.