NEUROENDOCRINE RESPONSES TO STRESS
The body’s principal physiological responses to stress stimuli
are mediated by the sympathoadrenal system (SAS), functionally
separable into the sympathetic nervous system (SNS)
and the adrenal medulla (AM), and the hypothalamic-pituitaryadrenocortical
(HPA) axis. Such responses are automatically
generated and coordinated in the brain; however, as Dinges1
has pointed out, “there is also recognition that humans cognitively
assess potential stressors for their perceived or real threat
potential, and the brain then orchestrates the physiological and
behavioral responses to the stressor.”
A schematic representation of the stress system (adapted
from Chrousos2) is provided in Fig 1. As shown on the right
side of the figure, acute activation of the SAS gives rise to
increased production by the adrenal medulla of epinephrine (E)
and norepinephrine (NE). Increased activity of the SNS also
occurs, with enhanced release of NE and neuropeptide