Mechanisms by which stressful stimuli activate the pituitary-adrenal system

Stress-induced activation of the pituitary-adrenal system appears to be mediated predominantly by hypothalamic neurons containing ovine corticotropin-releasing factor (oCRF) and vasopressin in the region of the paraventricular nucleus (PVN). Other mediators such as catecholamines, serotonin, angiotensin, and "tissue CRF" may also play a role under certain conditions. Several weeks after ablation of the PVN the response to stress is largely restored while the plasma adrenocorticotropin rise normally elicited by adrenalectomy is still strongly inhibited and immunoreactive oCRF is depleted from the stalk-median eminence region.