卤代芳烃类化合物的早期妊娠毒性动物模型检测方法的建立

Establishment of a Protocol for Assessment of Polyhalogenated Aromatic Hydrocarbon Toxicity in Early Pregnant Mice

目的建立一套动物模型检测方案,用于筛选和研究对人类和动物早期妊娠有影响的环境卤代芳烃类污染物。方法利用TCDD作为初始研究标准化合物,以NIH小鼠建立动物早期妊娠模型评估方案,包括剂量-反应评估(DRE)、着床前后毒性比较(PPP)、子宫蜕膜细胞反应(DCR)和胚胎转移速率(ETR)分析。结果DRE发现TCDD剂量依赖性地引起了第9天胚胎数量的显著减少。PPP比较发现100 ng/(kg.d)对胚胎着床前期影响显著大于着床后期;胚胎重量评估发现,TCDD在妊娠早期的不同时间给药均影响了胚胎的发育,造成发育迟缓,重量减轻。DCR检测发现TCDD处理显著抑制(P<0.01)假孕小鼠子宫蜕膜。ETR分析发现TCDD未影响胚胎在输卵管中的转移速度,但造成分裂卵发育迟缓,着床前分裂卵丢失(P<0.05)。对出生前胚胎成活率观察发现,TCDD可造成出生前胎儿死亡,胎儿成活率低于妊娠中期的胚胎成活率。结论TCDD对着床前胚胎的毒性明显大于着床后,并具有持续毒性的特点。其机理涉及抑制子宫蜕膜细胞反应、造成着床前分裂卵的丢失或发育的不同步。

Objective To establish an experimental animal model and protocol for screening and assessment of the toxicity of polyhalogenated aromatic hydrocarbons on early embryos in pregnant mice. Methods Using TCDD as the initial research standard compound, animal model for assessing polyhalogenated aromatic hydrocarbon toxicity was established in early pregnant NIH mice. The series of experiments included： 1. Dose-response evaluation. 2. Preversus post-implantation analysis. 3. Decidua cell response. 4. Embryo transport rate analysis. Results The number of implantation sites decreased significantly （ P 〈 O. 05） with the occurrence of post-implant embryo death and retardation of embryo development when the mice received TCDD in a dose of 50 and 100 ng/（kg· d）. This treatment inhibited uterine decidua growth in pseudopregnant mice significantly （P 〈 0.01 ）. Preversus post-implantation analysis revealed that pre-implantation stage is more sensitive than post-implantation stage. The embryo transport rate was not changed in TCDD treated animals. But the embryos in the oviduct were observed to show un-synchronization in development with a proportion of embryo loss. The d18 survival rate was significantly lower than the d9 ones. Conclusion The results of this study showed that pre-implantation embryos are more sensitive to TCDD than post-implantation embryos. It exerts continuous effects on the pregnant mice, causing a decreased number of fetuses before birth. The mechanism involved may include inhibition of DCR, un-synchronized cleavage of zygotes, and pre-implantation embryo loss. This protocol can be used to analyze and screen polyhalogenated aromatic hydrocarbons in the environment.