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. Author manuscript; available in PMC: 2021 Oct 6.
Published in final edited form as: Clin Auton Res. 2020 Oct 6;30(5):409–421. doi: 10.1007/s10286-020-00729-7

Figure 2: Summary of stress-response mechanisms and modulatory role of estrogen.

Figure 2:

HPA, hypothalamic pituitary adrenal (HPA) axis; SNS, sympathetic nervous system. As a first response to a distress signal (Stress), the hypothalamus activates the SNS by sending signals through the sympathetic nerves to effector organs (heart, blood vessels). As the surge in sympathetic activity subsides, the hypothalamus activates the second component of the stress response system, the HPA axis. Cortisol, the end product of HPA axis stimulation exerts a negative control on inflammation, therefore inhibiting the inflammatory response and sympathetic stimulation. High circulating levels of estrogen stimulate the HPA axis while inhibiting inflammation and the SNS. Lines with arrow (↓) show excitatory effect. Lines with bar (⊥) show inhibitory effect.