Adults could be at greater risk of becoming anxious and
vulnerable to poor mental health if they were deprived of certain hormones
while developing in the womb according to new research by scientists at Cardiff
and Cambridge universities.
New research in mice has revealed the role of the placenta
in long-term programming of emotional behaviour and the first time scientists
have linked changes in adult behaviour to alterations in placental function.
Insulin-like growth factor 2 has been shown to play a major
role in foetal and placental development in mammals, and changes in expression
of this hormone in the placenta and foetus are 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," according to
Professor Lawrence Wilkinson, a behavioural neuroscientist from Cardiff
University's School of Psychology who led the research.
"We were interested in how disrupting this balance
could influence emotional behaviours a long time after being born, as an
adult," he added.
Supply of nutrients
In order to explore how a mismatch between supply and demand
of certain nutrients might affect humans, Professor Wilkinson and his
colleagues Dr Trevor Humby, Mikael Mikaelsson both also from Cardiff University
and Dr Miguel Constancia of Cambridge University, examined the behaviour of
adult mice with a malfunctioned supply of a vital hormone.
Dr Humby added, "We achieved this by damaging a hormone
called Insulin-like growth factor-2, important for controlling growth in the
womb. 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 behaviour. This is the first
example of what we have termed 'placental-programming' of adult behaviour. 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 behaviour, and possibly
vulnerability to brain and mental health disorders, are sown much earlier than
Although these studies were carried out in mice, the
findings may have wider implications for human development. Further studies are
planned to investigate the brain mechanisms linking early life events,
placental dysfunction and the emotional state of adults.