Serotonin and stress

Forty-five years after its discovery, brain serotonin (5-HT) is still the subject of intense research aimed at understanding ifs role in stress adaptation. At the presynaptic level, numerous stressors increase nerve firing and extracellular 5-HT at the level of serotonergic cell bodies or nerve terminals. Different studies have reported stressor- and region-specific changes in extracellular 5-HT, a view challenged by electrophysiological and neurochemical evidence for a nonspecific response of serotonergic neurones to stressors when activity/arousal is taken into account. In addition, early studies indicate that stress-induced elevation in 5-HT synthesis, a key counter-regulatory process allowing serotonergic homeostasis, is mediated by specific neuroendocrine mechanisms. In addition to the multiplicity of postsynaptic 5-HT receptors and their specific regulation by corticoids, specificity to stressors is also underscored when considering one receptor type such as the 5-HT1A receptor. Stress studies should consider the past experience and the genetic status of the individual as key modulators oft he serotonergic responses to stress. (C) 1999 American College of Neuropsychopharmacology. Published by Elsevier Science Inc.