Apr. 6, 2013 —

Science Daily/British Neuroscience Association

Exposure of the developing fetus to excessive levels of stress hormones in the womb can cause mood disorders in later life and now, for the first time, researchers have found a mechanism that may underpin this process, according to research presented April 7 at the British Neuroscience Association Festival of Neuroscience (BNA2013) in London.

Adverse environments experienced while in the womb, such as in cases of stress, bereavement or abuse, will increase levels of glucocorticoids in the mother, which may harm the growing baby. Glucocorticoids are naturally produced hormones and they are also known as stress hormones because of their role in the stress response.

"The stress hormone cortisol may be a key factor in programming the fetus, baby or child to be at risk of disease in later life. Cortisol causes reduced growth and modifies the timing of tissue development as well as having long lasting effects on gene expression," she will say.

Puberty is another sensitive time of development and stress experienced at this time can also be involved in programming adult mood disorders. Prof Holmes and her colleagues have found evidence from imaging studies in rats that stress in early teenage years could affect mood and emotional behaviour via changes in the brain's neural networks associated with emotional processing.

Prof Holmes will say: "We showed that in stressed 'teenage' rats, the part of the brain region involved in emotion and fear (known as amygdala) was activated in an exaggerated fashion when compared to controls. The results from this study clearly showed that altered emotional processing occurs in the amygdala in response to stress during this crucial period of development."

http://www.sciencedaily.com/releases/2013/04/130407090835.htm