title: Serotonin secretion by human carcinoid BON cells.
abstract: BON cells are human carcinoid cells that secrete serotonin (5-HT) and various peptides. Secretion of [(3)H]5-HT by cell cultures was investigated. Acetylcholine (Ach) stimulated secretion through a somatostatin-sensitive muscarinic pathway, whereas isoproterenol was inefficient. [(3)H]5-HT secretion also was induced by Ca(2+) in the presence of the ionophore A-23187 or after digitonin permeabilization. These two processes were insensitive to stomatostatin. Ba(2+) induced an efficient somatostatin-sensitive [(3)H]5-HT secretory response. Secretion also was analyzed at the single-cell level, using carbon fiber amperometry and evanescent-field fluorescence microscopy, after labeling the secretory vesicles by transfection of the cells with a NPY-GFP construct. Both techniques revealed slow kinetics of secretory responses, suggesting that ready-to-fuse vesicles do not accumulate in these cells. Single secretory vesicles were imaged either in resting conditions or after addition of Ca(2+) ions to digitonin-permeabilized cells. The three-dimensional movements of the vesicles before exocytosis were analyzed. The mean velocity of vesicles that released their content was lower than that of silent ones. Even in the case of mobile vesicles, exocytosis often was preceded by a period of arrest lasting at least 15 seconds, consistent with a docking/priming step.
authors.affiliation: Biologie moléculaire et cellulaire de la secretion, CNRS UPR 1929, Institut de Biologie Physico-Chimique, 75005 Paris, France.
authors.forename: Viet Samuel
authors.initials: VS
authors.lastname: Tran
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Marion-Audibert
authors.forename: Erdem
authors.initials: E
authors.lastname: Karatekin
authors.forename: Sebastien
authors.initials: S
authors.lastname: Huet
authors.forename: Sophie
authors.initials: S
authors.lastname: Cribier
authors.forename: Koulm
authors.initials: K
authors.lastname: Guillaumie
authors.forename: Catherine
authors.initials: C
authors.lastname: Chapuis
authors.forename: Claire
authors.initials: C
authors.lastname: Desnos
authors.forename: François
authors.initials: F
authors.lastname: Darchen
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Henry
mesh_terms: D002276:Carcinoid Tumor; D045744:Cell Line, Tumor / Q000378:metabolism; D004759:Enterochromaffin Cells / Q000378:metabolism*; D006801:Humans; D010190:Pancreatic Neoplasms; D012701:Serotonin / Q000378:metabolism*
chemical_list: D012701:Serotonin