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. Author manuscript; available in PMC: 2016 May 14.
Published in final edited form as: Compr Physiol. 2016 Mar 15;6(2):603–621. doi: 10.1002/cphy.c150015

Figure 2.

Figure 2

Temporal dynamics of HPA axis stress responses. In response to stress, ACTH is released within minutes of stimulation. The extent of ACTH release is limited by rapid, non-genomic fast feedback mechanisms (usually peaking within 15 min of stressor onset)(see text). Due to the time needed for ACTH to access the adrenal cortex and promote glucocorticoid synthesis and release, there is a substantial delay between time-to-peak for corticosterone relative to ACTH (usually within 30–60 minutes). In addition to shutdown by fast feedback inhibition of ACTH release, the time course of the corticosterone response (usually on the order of 2 hours) can be modulated by delayed glucocorticoid feedback as well as factors controlling glucocorticoid metabolism. The timing of both ACTH and corticosterone responses are dependent on stressor modality and intensity. Modified from (68).