HPA Axis
Hypothalamo-Pituitary-Adrenocortical
stress is perceived by limbic system
neurons in the limbic system activate the HPA axis
- CRH neurons in hypothalamus release CRH at median eminence
- CRH stimulates release of ACTH from cells in the anterior pituitary
- ACTH stimulates both synthesis and release of glucocorticoids from adrenal cortex
- glucocorticoids act, in part, to mobilize energy for the fight or flight response
- glucocorticoids also act to restrain the HPA axis by inhibiting hormone release at the level of the hypothalamus, pituitary, and higher brain regions (limbic system)
CRH: corticotrophin-releasing hormone
ACTH: adrenocorticotrophin hormone