Although the placenta is only part of the human development for a brief nine months, it is an under appreciated and necessary part of the process. The blood vessels in the placenta, which appear to resemble tree roots, deliver essential oxygen and nutrients from the mother to the baby.

Scientists are finding that the placenta is far more than a passive filter between the mother and the fetus. In an innovative study conducted by researchers from Vanderbuilt University and the Keck School of Medicine at the University of Southern California’s Zilkha Neurogenetic Institute, have found conclusive evidence that serotonin is supplied to the fetus forebrain through the placenta, not the mother’s blood as previously thought. The paper on their work is titled, “A transient placental source of serotonin for the fetal forebrain,” and can be found in the April 2011 edition of the journal Nature.

This research will pave he way for new treatments that could impact mental illness and cardiovascular disease.

“Our research indicates that the placenta actually synthesizes serotonin, and the serotonin is released from the placenta into the fetal bloodstream where it can reach the fetal brain,” said lead author Alexandre Bonnin, Ph.D. “The placenta was seen as a passive organ, but we now know that it has significant synthetic capabilities and has a much more critical role in developmental programming of the fetus than previously thought.”

Pat Levitt, Ph.D., director of the Zilkha Neurogenetic Institute and co- author of the paper, worked with Bonnin and other researchers to invent included the invention of a unique technology known as a “placentometer,” which monitors substances that are being passed through the placenta of the mother mouse to her fetus. This technology was created in order to find a way to incorporate genetic models of human disease, and hopefully lead to targeted therapies that will allow treatment of the mother while the fetus remains undisturbed, or the other way around.

“The findings by Dr. Bonnin and his collaborators open the door for future studies examining the potential role for targeted interventions in high-risk pregnancies where a perturbed intrauterine environment might negatively impact fetal brain development,” said Istvan Seri, professor of pediatrics at Keck School, and director at the Center for Fetal and Neonatal Medicine at Children’s Hospital Los Angeles. “However, it will take many more basic, translational and clinical trials and many years until we can provide evidence that approaches like this one work.”

The neurotransmitter serotonin is known to impact the brain, heart and pancreas development and affect a human’s well being. Neurons that synthesize serotonin develop in the hindbrain of the fetus, where the heart, respiration and other critical functions take place. This takes place in the early stages of the fetus’ development. The neurons eventually travel to the forebrain, the home where higher cognitive functions and emotions are regulated.

According to the study, during the gap in time between the development of the hindbrain and the forebrain the placenta plays an essential part in bringing the serotonin to the forebrain. Mother’s nutrition plays a role, as it is the only source of the essential amino acid tryptophan.

“An altered capacity of the placenta to make and release serotonin could affect the levels of serotonin in the human forebrain as it does in the mouse,” said Levitt. “Developmental programming of the fetal brain can set the stage for adult-onset health impacts including heart disease, diabetes and mental illness.”

There is an increasing amount of evidence that indicates the development of the fetus could affect the body as the baby grows, causing chronic health problems and mental disorders, like emotional and learning disabilities, depression and anxiety disorders.

“Bonnin’s research may be of particular importance for early onset brain disorders, such as autism, Asperger’s syndrome and pediatric obsessive-compulsive disorder, where investigators are considering a role for serotonin based on human genetic studies,” said Randy Blakely, Ph.D., director of the Vanderbilt Conte Center, another collaborator on the paper.



About the author:

Ron White is a two-time U.S.A. Memory Champion and memory training expert. As a memory keynote speaker he travels the world to speak before large groups or small company seminars, demonstrating his memory skills and teaching others how to improve their memory, and how important a good memory is in all phases of your life. His CDs and memory products are also available online at



Scientific American – Fetal Armor: How the Placenta Shapes Brain Development:

Science News – Critical Role of Placenta in Brain Development Demonstrated: