The main driving force behind glucocorticoid secretion is corticotropin-releasing hormone (CRH) acting in synergy with arginine-vasopressin (AVP), both of which are primarily released from the paraventricular nucleus (PVN) of the hypothalamus. The CRH stimulates the corticotroph cells in the anterior pituitary to secrete corticotropin (ACTH), which, in turn, influences the adrenal cortex. Three separate regulatory forces are involved in the secretion of gluco-corticoids under physiological conditions and during times of stress. A circadian rhythm of basal activity is under the influence of the suprachiasmatic nucleus. Stress-induced responses are more complex and involve afferent inputs from numerous brain regions, including the locus ceruleus and autonomic systems in the brain stem, the amygdala-hippocampus complex, and the cerebral cortex. Finally, a feedback inhibitory input is provided by glucocorticoids.
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