Mechanisms underlying the role of glucocorticoids in the early life programming of adult disease.

Compelling epidemiological evidence suggests that exposure to an adverse intrauterine environment, manifested by low-birth weight, is associated with cardiometabolic and behavioural disorders in adulthood. These observations have led to the concept of 'fetal programming'. The molecular mechanisms that underlie this relationship remain unclear, but are being extensively investigated using a number of experimental models. One major hypothesis for early life physiological programming implicates fetal overexposure to stress (glucocorticoid) hormones. Several animal studies have shown that prenatal glucocorticoid excess, either from endogenous overproduction with maternal stress or through exogenous administration to the mother or fetus, reduces birth weight and causes lifelong hypertension, hyperglycaemia and behavioural abnormality in the offspring. Intriguingly, these effects are transmitted across generations without further exposure to glucocorticoids, which suggests an epigenetic mechanism. These animal observations could have huge implications if extrapolated to humans, where glucocorticoids have extensive therapeutic use in obstetric and neonatal practice.