Which hypothalamic releasing hormone stimulates the release of ACTH from the anterior pituitary?

• A. Gonadotropin RH
• B. Corticotrophin RH
• C. Thyrotropin RH
• D. Growth Hormone RH

Answer: (B)

Corticotropin-releasing hormone (CRH) from the hypothalamus stimulates ACTH release from the anterior pituitary. CRH binds to receptors on corticotroph cells, triggering a signaling cascade that increases ACTH synthesis and secretion, often with a helping role from vasopressin during stress. ACTH then acts on the adrenal cortex to produce cortisol, which provides feedback to dampen CRH and ACTH production. The other hypothalamic releasing hormones regulate different pituitary targets (gonadotropins, thyroid-stimulating hormone, growth hormone) and do not primarily control ACTH release.