Psychosocial vs. "physical" stress situations in rodents and humans - Roleof neurotrophins

Nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are well-studied polypeptide growth factors involved in the development and mai ntenance of specific peripheral and central populations of neuronal cells. In addition to its role as a neurotrophic agent, NGF controls very complex functions in vertebrate physiology. A variety of cells outside the nervous system are in fact able to synthesize NGF including epithelial cells, fibro blasts, lymphocytes, and macrophages. NGF target cells have been identified in the nervous, immune. and endocrine systems, suggesting that NGF ma?; op erate through multiple paths to ultimately regulate physiological homeostas is and behavioral coping. We used a mouse model of social stress to demonst rate that NGF levels increase both in plasma and in the hypothalamus follow ing intermale aggressive interactions. The investigation has been extended to other species, including humans, to show that labour, lactation, and the anticipation of the first jump with a parachute also result in increased N GF plasma levels and in changes in the distribution of NGF receptors on lym phocytes. BDNF activation is caused by both physical and social stress even ts. The aim of this review is to (1) outline the current understanding of t he roles of NGF and BDNF in stress-related physiological changes in vertebr ates, in particular for physical vs, psychological stressors, which may act ivate both similar and different neurobiological pathways, and (2) summariz e recent efforts to derive pharmacological strategies from the increasing b ody of BDNF and NGF neurobehavioral data. (C) 2001 Elsevier Science Inc. Al l rights reserved.