2,3,7,8-四氯苯二噁对小鼠胚胎毒作用的研究

Effects of TCDD on the embryo lost at early pregnancy and survive rate at born

目的 探讨动物妊娠早期接触2 ,3 ,7,8 四氯苯二(TCDD)后造成胚胎丢失的原因以及对小鼠成活率的影响。方法 90只妊娠NHI小鼠分9组,在妊娠的第1天,第2天和第3天分别观察胚胎转移率、检测血清雌二醇和孕酮含量;2 40只妊娠NIH小鼠分2 4组,于妊娠第9天和第18天测定子宫重量,观察胚胎成活情况。结果 与正常对照组胚胎数比较,TCDD未影响胚胎转移率,但造成着床前胚胎丢失(14±4 2 0 ,4 63±6 0 9,P <0 0 1) ;不同时期染毒均可降低胚胎和胎儿成活率(P <0 0 0 1) ;血清雌二醇含量升高(P <0 0 0 1)、孕酮水平下降(P <0 0 1)。结论 TCDD对胚胎和母体均具有毒性,血清类固醇激素的改变可影响子宫功能,造成第9天胚胎成活率下降;同时TCDD具有持续毒性的特点,使出生前第18天胚胎成活数低于第9天胚胎成活数。

Objective The aim of this study was to understand the mechanism of TCDD induced embryo lost in early pregnancy and the ultimate outcome at the end of pregnancy.Method 9 groups each containing 10 pregnancy NIH mice were orally dosed with 0,50 and 100 ng/(kg·d) of TCDD at the day1,2 and 3 of pregnancy to evaluate the embryo transport rate change in oviduct,and detected the reproduction hormones.Other 24 groups of pregnancy NIH mice were orally dosed with 0,2,50 and 100 ng/(kg·d) of TCDD at the intervals of d1-d8,d1-d3,d4-d8 to observe the uterus function and vitality of embryos by weighing the uterus and counting embryo numbers at d9 and d18 of pregnancy.Results The result showed that the transport rate was not altered,but the pre-implanted embryo number was significantly decreased (14±4.20,4.63±6.09,P<0.01) by TCDD of experimental doses.TCDD Administrated at different stages caused significant estrogen level elevation and progesterone level declination.These led to the uterus function alteration and the continuing embryo survive rate decreased from d9 to d18.Conclusion The reason of TCDD caused implantation sites decrease is not related with embryo transport rate change,but with the lost of embryo with in the oviduct.TCDD has sustained effects on the uterus function and development of embryo.