Figure 1.

The HPA-axis and adrenal glucocorticoid synthesis. The Hypothalamus-pituitary-adrenal-axis (also known as “stress axis”) represents the sequence of endocrine events between the hypothalamus (green), the anterior pituitary gland (blue), and the cortex of the adrenal gland (red). Corticotropin-releasing hormone (CRH) secreted from the paraventricular neurons (PVNs) of the hypothalamus stimulates adrenocorticotropic hormone (ACTH, corticotropin) release from the anterior pituitary, which consequently stimulates the production of glucocorticoids in the steroidogenic cells of the zona fasciculata in the adrenal cortex. Blue lines indicate negative feedback. The right-hand panel shows the biochemical reactions leading to glucocorticoid-synthesis in humans and in rodents. The synthesizing enzymes are shown in yellow (and light-red for the human CYP17). The (so far known) subcellular localization of the steroidogenic enzymes in the mitochondria or the ER is highlighted by dotted-line boxes.