University of Cambridge. UK: Increased
levels of stress hormones can lead pregnant mice to overeat, but affect
growth of the foetus and, potentially, the long term health of the
offspring, according to a study published today.
In
the Journal of Physiology, researchers at the Department of Physiology,
Development and Neuroscience at the University of Cambridge examine
whether levels of the stress hormones known as glucocorticoids can
influence the supply of glucose from mother to foetus. Glucocorticoids
are important in regulating metabolism in adults as well as in the
foetus. Levels of the hormone are raised by stress related to the
physical or social environment, disease or pregnancy.
Pregnant mice received the natural glucocorticoid corticosterone at
different times during pregnancy via their drinking water, either from
days 11 to 16, days 14-19, or not at all; pregnancy in mice lasts 21
days and the days on which corticosterone was given corresponds to
different developmental phases of the placenta. This treatment was
designed to produce glucocorticoid levels in the mother similar to those
seen in stressful conditions. The animals were either allowed to eat
freely or their food intake limited to that of normal, untreated mice.
The researchers then measured the amount of glucose crossing the
placenta, the organ that supplies all of the substances required for
foetal growth, in a specific period of time.
The researchers found that when corticosterone was given later in
pregnancy and the mice allowed to eat freely, the mother ate more but
her placenta was less able to transport glucose to the foetus, leading
to a decrease in the size of the foetus. This effect was not seen when
the hormone was administered earlier in pregnancy or when the diet was
restricted. They believe this may be because, under stress and with an
unlimited diet, the activity of certain genes in the placenta was
modified, including that of the gene Redd1. This gene is believed to
signal availability of other substances, like oxygen, and to interact
with intracellular pathways regulating growth and nutrient uptake in
other tissues of the body. The team believe that future studies may
prove this molecule is important in the placenta in linking
environmental effects to the nutrition of the foetus.
Together with previous work, the findings show that maternal
glucocorticoids regulate foetal nutrition by acting on the placenta. The
researchers believe that glucocorticoid levels in pregnant women may
therefore determine the specific combination of nutrients received by
the foetus and influence the long term metabolic health of their
children as a result.
Dr Owen Vaughan from the University of Cambridge says: “The foetuses of
the mice with raised levels of the stress hormone tended to be smaller,
despite the mother overeating, suggesting that a mother’s stress levels
may affect her child’s growth. We showed that this is likely to be
because the stress hormone reduced the ability of the placenta to pass
essential nutrients to the foetus.”
The researchers believe this study may have implications for women
stressed during pregnancy or treated clinically with glucocorticoids, if
the mechanisms are similar in humans, though it is unclear yet the
extent to which changes in the ability of the placenta to transport
nutrients to the foetus exacerbate or protect the child from the
potential adverse effects of glucocorticoid overexposure during
pregnancy. Nor is it clear whether maternal diet influences the outcome
of glucocorticoid overexposure during human pregnancy.
Professor Abby Fowden, who led the research, adds: “It may be that by
changing her diet, a mother can counter the effects of stress hormones
on the human placenta. In other words, a mother’s ‘hormonal profile’ may
dictate the most appropriate diet for a successful outcome of
pregnancy. We need more research in this area before we can start giving
such advice, however.”
Reference
Vaughan OR, Fisher HM, Dionelis KN, Jefferies EC, Higgins JS, Musial B,
Sferruzzi-Perri AN & Fowden AL (2015) Corticosterone alters
materno-foetal glucose partitioning and insulin signalling in pregnant
mice. DOI: 10.1113/jphysiol.2014.287177 - See more at:
http://www.cam.ac.uk/research/news/mothers-stress-hormone-levels-may-affect-foetal-growth-and-long-term-health-of-child#sthash.vGw59ZHl.dpuf