The role of the placenta in transmitting disturbed serotonin levels from the maternal environment

The placenta has evolved several times throughout the animal kingdom and plays a pivotal role in the regulation of normal growth and embryonal development. Although it has shaped regulatory mechanisms to respond to the continuously altering maternal environment, the placenta does not protect the embryo against all adverse effects. Serotonin plays a key role in the early development across vertebrates. Alterations in the maternal serotonergic system, for instance using selective serotonin reuptake inhibitors (SSRIs), may have deleterious effects for the developing embryo. The complex maternal-fetal interaction makes it unclear whether exposure to adverse environments increases the risk for adverse outcomes in the offspring, and if so what the underlying mechanisms are.