Early environmental manipulations can impact on the developing nervous system, contributing to shape individual differences in physiological and behavioral responses to environmental challenges. In particular, it has been shown that disruptions in the mother-infant relationship result in neuroendocrine, neurochemical and behavioural changes in the adult organism, although the basic mechanisms underlying such changes have not been completely elucidated. Recent data suggest that neurotrophins might be among the mediators capable of transducing the effects of external manipulations on brain development. Nerve growth factor and brain-derived neurotrophic factor are known to play a major role during brain development, while in the adult animal they are mainly responsible for the maintenance of neuronal function and structural integrity. Changes in the levels of neurotrophic factors during critical developmental stages might result in long-term changes in neuronal plasticity and lead to increased vulnerability to aging and to psychopathology.