Regulation of corticoid and serotonin receptor brain system following early life exposure of glucocorticoids: long term implications for the neurobiology of mood.

Potent glucocorticoids (GC) administered early in life have improved premature infant survival dramatically. However, these agents may increase the risk for physical, neurological and behavior alterations. Anxiety, depression and attention difficulties are commonly described in adolescent and young adult survivors of prematurity. In the present study we administered vehicle, dexamethasone, or hydrocortisone to Sprague-Dawley rat pups on postnatal days 5 and 6, mimicking a short term clinical protocol commonly used in human infants. Two systems that are implicated in the regulation of stress and behavior were assessed: the limbic-hypothalamic-pituitary-adrenal axis [LHPA; glucocorticoid and mineralocorticoid receptors within] and the Serotonin (5-HT) system. We found that as adults, male Sprague-Dawley pups treated with GC showed agent specific altered growth, anxiety-related behavior, changes in corticoid response to novelty and gene expression changes within LHPA and 5-HT-related circuitry. The data suggest that prolonged GC-receptor stimulation during the early neonatal period can contribute to the development of individual differences in stress response and anxiety-related behavior later in life.