pituitary hormone, anterior corticotropin ACTH Adrenocorticotropic hormone An anterior pituitary hormone that stimulates the secretion of CORTICOSTEROIDS and induces growth of the ADRENAL CORTEX. It is a single-chain polypeptide of about 39 amino acids, the first 24 of which are identical in all species. This 24-amino acid segment is said to be responsible for the biological activity of the peptide while the remaining 15-amino acid segment is said to be necessary for any immunological specificity. IMR:0100195 KEGG:C02017 MeSH:D000324 molecule_role