A high level of maternal stress during pregnancy could lead to an altered gene reaction in nerve cells of a child, with implications for the latter’s later life. This is suggested by a study recently published in the renowned journal Proceedings of the National Academy of Sciences (PNAS).
Studies in animals and humans have so far shown that stress, such as depression, malnutrition or hormonal transfer to the fetus during pregnancy, increases the risk of the unborn child suffering from a number of health problems later in life. Increased stress during this critical phase of fetal development is associated with a number of adult-phase health problems such as increased sensitivity to stress, cognitive deficits and increased susceptibility to psychiatric disorders and behavioral upsets.
A possible molecular mechanism responsible for this stress transfer has now been identified. Stress hormones trigger a change in an important epigenetic process, DNA methylation, which leads to the expression of different genes over a longer period of time. Although stress hormones are necessary for fetal brain development, too much of them have been shown to be harmful.
The scientists used human brain cells to observe the effects of stress hormones during fetal development. They found that chronic stress during early neuronal formation, neurogenesis, leads to a long-term alteration of genes through epigenetic mechanisms. In addition, they were able to show that these epigenetic changes lead to an increased sensitivity to subsequent stress.
In order to transfer these findings from the laboratory to humans, umbilical cord blood cells from newborns who were exposed to high stress during pregnancy (such as depression and anxiety disorders of the mother or a stress hormone administration) were also examined. It was observed that epigenetic changes in the neurons and those found in the genes of stressed newborns were consistent. These epigenetic markers can be seen as "cellular memories" of past stress that could affect the individual's sensitivity to future stress.
Stress before childbirth seems to change not only the development of nerve cells but also the response to stress in later life. This knowledge provides information about the possible long-term effects of early environmental influences, but could also help to develop strategies for preventive measures.
Glucocorticoid exposure during hippocampal neurogenesis primes future stress response by inducing changes in DNA methylation. Nadine Provençal, Janine Arloth, Annamaria Cattaneo, Christoph Anacker, Nadia Cattane, Tobias Wiechmann, Simone Röh, Maik Ködel, Torsten Klengel, Darina Czamara, Nikola S. Müller, Jari Lahti, PREDO team, Katri Räikkönen, Carmine M. Pariante, Elisabeth B. Binder. Proceedings of the National Academy of Sciences Aug 2019, 201820842; DOI:10.1073/pnas.1820842116