Babies deprived of certain hormones in the womb could be at greater risk of being anxious as adults, according to new research with mice.
Insulin-like growth factor-2 has been shown to play a major role in fetal and placental development in mammals—and changes in expression of the hormone have been implicated in growth restriction in the womb.
“The growth of a baby is a very complex process and there are lots of control mechanisms which make sure that the nutrients required by the baby to grow can be supplied by the mother,” says Trevor Humby, a behavioral neuroscientist at Cardiff University.
“We were interested in how disrupting this balance could influence emotional behaviors a long time after being born, as an adult.”
In order to explore how a mismatch between supply and demand of certain nutrients might affect humans, Humby and colleagues examined the behavior of adult mice with a malfunctioned supply of a vital hormone.
“We achieved this by damaging a hormone called Insulin-like growth factor-2, important for controlling growth in the womb,” Humby says.
“What we found when we did this was an imbalance in the supply of nutrients controlled by the placenta, and that this imbalance had major effects on how subjects were during adulthood—namely, that subject became more anxious later in life.
“These symptoms were accompanied by specific changes in brain gene expression related to this type of behavior. This is the first example of what we have termed ‘placental-programming’ of adult behavior.
“We do not know exactly how these very early life events can cause long-range effects on our emotional predispositions, but we suspect that our research findings may indicate that the seeds of our behavior, and possibly vulnerability to brain and mental health disorders, are sown much earlier than previously thought.”
Although these studies were carried out in mice, the findings may have wider implications for human development, the researchers say. Further studies are planned to investigate the brain mechanisms linking early life events, placental dysfunction, and the emotional state of adults.