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Hypothalamic-Pituitary-Adrenal Axis

The hypothalamic-pituitary-adrenal (HPA) axis is a hormonal system comprising the paraventricular nucleus of the hypothalamus, the pituitary gland, and the adrenal gland. This axis controls release of steroid hormones, which include glucocorticoids, mineralocorticoids, and didehydroepiandrosterone (DHEA). Glucocorticoids, named for their role in raising blood sugar, are elevated by stressors and influence metabolism, constrain the immune system, and affect the vasculature. Mineralocorticoids control salt and water balance. The function of DHEA is less well understood, despite DHEA and DHEA sulfate being the most abundant steroid hormones.

The activity of the HPA axis varies over the course of the day; glucocorticoids (cortisol and corticosterone) are released into the vascular system at peak levels early in the day and at the lowest levels during the evening hours in ...

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