Objective:To explore the effect of benzo(a)pyrene(Ba P)on Wnt signaling in mice uteri during early pregnancy. Methods:Adult female and male Kunming mice were mated to produce pregnancy. The pregnant mice were divided into two groups :control group(n=45);Ba P-treated group(n=45)

and then received corn oil and 0.2 mg/(kg·d)Ba P respectively from D1. The uteri were collected on pregnant 4 to 6 days respectively and the implantation numbers were counted. Real-time PCR(q RT-PCR)

Western blot and immunohistochemistry(IHC)were used to detect the gene expression of Wnt signaling pathway. Results:The implantation numbers were reduced in Ba P-treated group than in control group(P=0.000). The results of RT-PCR revealed down-regulated of m RNA levels of Wnt7 a in Ba P-treated group(P=0.000)

whereas the expression of β-catenin was elevated in this group(P=0.002

P=0.003

P=0.011). Western blot and IHC also showed the up-regulated expression of β-catenin

and the reduced expression of Wnt7 a in Ba Ptreated group. Conclusion :Ba P can lead to the aberrant expression of Wnt7 a and β-catenin

which might interfere embryo implantation.