Figure 3 displays a schematic of the HPA system. The system involves regions within the brain including the hypothalamus that produces corticotropin-releasing hormone (CRH), and the pituitary that releases adrenocorticotropin hormone (ACTH). Cortisol and other glucocorticoid hormones are produced and secreted outside the brain by the adrenal glands. The release of CRH from the hypothalamus stimulates ACTH release from the pituitary that triggers the secretion of glucocorticoids, including cortisol, from the adrenal glands. In turn, a negative feedback effect on the system occurs at the level of the pituitary as well as other brain sites including the hypothalamus, hippocampus, and regions in the frontal cortex (Diorio et al. 1993). Therefore, abnormalities in the brain structures associated with negative feedback on the HPA system may produce maladaptive patterns of hormone secretion that influences behavioral and emotional regulation.
