LAUSR

Abstract Triclosan is a broad-spectrum antibacterial agent and widely exists in environmental media and organisms. Triclosan exposure has been reported to have adverse effects on reproduction including embryo implantation disorder. During the embryo implantation window, it is vital that the endometrium develops into a receptive state under the influence of ovarian hormones. However, the effect of triclosan on embryo implantation and endometrial receptivity remains unclear. In the current study, we found a decreased embryo implantation rate, serum estrogen, and progesterone levels in mice exposed to triclosan from gestation days 0.5 to 5.5. Through RNA sequencing (RNA-seq), we identified nearly 800 differentially expressed genes, which were enriched in various pathways, including uterus development, inflammatory response, and immune system processes. Among those enriched pathways, the tight junction pathway is essential for the establishment of the receptive state of the endometrium. Then, genes involved in the tight junction pathway, including Cldn7, Cldn10, and Crb3, were validated by quantitative real-time polymerase chain reaction and the results were consistent with those from RNA-seq. Through immunofluorescence staining and western blotting, we confirmed that the tight junction protein levels of CLDN7 and CRB3 were increased. All these findings suggest that preimplantation triclosan exposure reduces the rate of embryo implantation through upregulating the expression of the tight junction genes and affecting the receptivity of the endometrium. Our data could be used to determine the sensitive time frame for triclosan exposure and offer a new strategy to prevent implantation failure. Summary Sentence Preimplantation triclosan exposure affects the receptivity of the endometrium by upregulating the expression of tight junction genes, thus reducing the rate of embryo implantation. Graphical Abstract