Adrenocorticotropic hormone is a peptide hormone involved in adrenal regulation, stress adaptation, glucocorticoid production, and coordination of endocrine responses to physiological demand. ACTH functions as the primary pituitary signal controlling cortisol synthesis within the adrenal cortex and plays a central role in activation of the hypothalamic-pituitary-adrenal axis.
The hormone stimulates glucocorticoid production, supports adrenal steroidogenesis, influences adrenal growth, and contributes to metabolic adaptation during stress physiology. Through regulation of cortisol synthesis, ACTH indirectly affects glucose metabolism, immune communication, vascular adaptation, circadian physiology, and energy mobilization pathways. These actions allow ACTH to coordinate endocrine adaptation during changing environmental and metabolic conditions.
ACTH is produced by corticotroph cells within the anterior pituitary gland. The hormone is generated through cleavage of the precursor protein proopiomelanocortin, which also produces additional peptide signaling molecules involved in endocrine regulation.
Production follows circadian rhythmic patterns with highest secretion commonly occurring in the early morning. Physical stress, emotional signaling, inflammation, hypoglycemia, and physiological demand can strongly stimulate release through hypothalamic corticotropin-releasing hormone pathways.
ACTH secretion is regulated mainly through hypothalamic CRH signaling and negative feedback from circulating glucocorticoids. Reduced cortisol signaling stimulates hypothalamic activation and pituitary release, while elevated cortisol suppresses further secretion through endocrine feedback pathways.
The hormone acts through melanocortin receptor systems located within the adrenal cortex that activate cyclic AMP signaling, steroidogenic enzyme pathways, and glucocorticoid synthesis mechanisms. Stress physiology, circadian timing systems, inflammatory cytokines, and autonomic nervous system signaling all influence secretion dynamics. Through these integrated endocrine feedback systems, ACTH coordinates adrenal physiology, stress adaptation, glucocorticoid signaling, and metabolic regulation.
ACTH drives adrenal cortisol synthesis through MC2R and cAMP–PKA signaling.
