The PE rat models were established and used as model group； the healthy rats were selected and used as control group. The primary trophoblasts were isolated and cultured from the chorionic trophoblast tissue of the PE rats. The trophoblasts in the logarithmic growth phase were selected as Neo group （transfected with pL-tdTomato-Neo plasmid） and mSnail group （transfected with pL-tdTomato-mSnail plasmid）， and the untreated cells were used as blank control group. Real-time fluorescence quantitative PCR （RT-qPCR） and Western blotting methods were used to detect the expression levels of Snail mRNA and protein in chorionic trophoblast tissue of the rats in control group and model group and in the cells in blank control group， Neo group and mSnail group. Transwell chamber experiment was used to determine the cell invasion abilities in blank control group， Neo group and mSnail group. Western blotting method was used to detect the expression levels of epithelial cadherin （E-cadherin）， neurogenic cadherin （N-cadherin） and Vimentin proteins in the cells.

Compared with control group， the expression levels of Snail mRNA and protein in the placenta chorionic trophoblast tissue of the rats in model group were decreased （P<0.05）；under fluorescence microscope， the transfection efficiencies in Neo group and mSnail group were both >80%. Compared with blank control group and Neo group， the expression levels of Snail mRNA and protein in the cells in mSnail group were increased（P<0.05）， the average number of cells passing through the micropore in each field of view was increased（P<0.05）， the expression level of E-cadherin protein was decreased （P<0.05），and the expression levels of N-cadherin and Vimentin proteins were increased（P<0.05）. Conclusion High expression of Snail can enhance the invasion ability of placental trophoblasts in the PE rats and its mechanism may be related to Snail’s promotion of the epithelial-mesenchymal transition of placental trophoblasts.