ENVIRONMENTAL STRESSORS IMPACT PLACENTATION THROUGH ACTIONS ON TROPHOBLAST, IMMUNE , AND ENDOTHELIAL CELL DYNAMICS [RNA-Seq]

Our environment is replete with chemicals that can affect embryonic and extraembryonic development. Dioxins, such as 2,3,7,8-tetrachlorodibenzodioxin (TCDD), are compounds affecting development through the aryl hydrocarbon receptor (AHR). TCDD exposures can lead to placental adaptations and at higher doses pregnancy termination. Deep intrauterine endovascular trophoblast cell invasion was a prominent placentation site adaptation to TCDD. TCDD-mediated placental adaptations were dependent upon maternal AHR signaling but not placental or fetal AHR nor the presence of a prominent AHR target, cytochrome P450 1A1 (CYP1A1). At the placentation site, TCDD stimulated CYP1A1 transcription within endothelial cells but not trophoblast cells. Immune and trophoblast cell behaviors at the uterine-placental interface were guided by the actions of TCDD on endothelial cells. In summary, we have identified an AHR regulatory pathway activated by environmental stressors affecting uterine and trophoblast cell dynamics and the formation of the hemochorial placenta. Pregnant rats treaatted with TCDD at gestational day (gd) 6.5 and placental-uterine inerface tissue was collected at gd 13.5.