What triggers the release of adrenocorticotropic hormone (ACTH)?

• A. Thyroid hormones
• B. Corticotropin-releasing hormone (CRH) from the hypothalamus
• C. Growth hormone
• D. Testosterone

Answer: (B)

The release of adrenocorticotropic hormone (ACTH) is primarily triggered by corticotropin-releasing hormone (CRH) produced in the hypothalamus. When the body experiences stress or low levels of cortisol, the hypothalamus secretes CRH into the portal circulation, which then stimulates the pituitary gland to release ACTH. This hormone subsequently acts on the adrenal cortex to promote the synthesis and release of cortisol, thereby playing a crucial role in the body’s response to stress.

The physiological link between CRH and ACTH release is essential for maintaining homeostasis, particularly in response to stressors. This regulatory mechanism is fundamental to the hypothalamic-pituitary-adrenal (HPA) axis, which is central to various adaptive responses in the body.