title: Corticotropin-releasing (CRH) activity of thymic peptides on CRH-insensitive corticotropic tumor cells.
abstract: A number of thymic preparations are known to stimulate corticotropin (ACTH) release from pituitary cells but it remains unclear whether this effect is mediated by the corticotropin-releasing hormone (CRH) receptor-associated pathway. We report here that thymosin fraction five (TF5), peptide MB-35 and possibly calf thymus histones can stimulate the release of ACTH from a CRH-insensitive variant of the mouse corticotropic cell line AtT20. The effective concentration range at which TF5 and MB-35 displayed their ACTH-releasing activity in a dose-dependent manner was 100 to 2,000 micrograms/ml and 10 to 100 ng/ml, respectively, whereas neither preparation induced a significant depletion of intracellular ACTH stores. Our data suggest that thymosin peptides can stimulate ACTH release from corticotrophs by a CRH receptor-independent mechanism.
authors.affiliation: Department of Biochemistry and Physiology, University of Reading, United Kingdom.
authors.forename: R G
authors.initials: RG
authors.lastname: Goya
authors.forename: M G
authors.initials: MG
authors.lastname: Castro
authors.forename: M J
authors.initials: MJ
authors.lastname: Hannah
authors.forename: Y E
authors.initials: YE
authors.lastname: Sosa
authors.forename: P J
authors.initials: PJ
authors.lastname: Lowry
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism*; D015592:Immunoradiometric Assay; D036341:Intercellular Signaling Peptides and Proteins; D051379:Mice; D009842:Oligopeptides / Q000494:pharmacology*; D010455:Peptides / Q000494:pharmacology*; D013947:Thymosin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D013953:Thymus Neoplasms / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000378:metabolism
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D009842:Oligopeptides; D010455:Peptides; C033782:thymosin fraction 5; C064563:thymic humoral factor gamma 2; C067684:peptide MB-35; D013947:Thymosin; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone