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Serotonin secretion by human carcinoid BON cells.
Viet Samuel Tran1, Anne-Marie Marion-Audibert, Erdem Karatekin
1Biologie moléculaire et cellulaire de la secretion, CNRS UPR 1929, Institut de Biologie Physico-Chimique, 75005 Paris, France.
Annals of the New York Academy of Sciences
|May 22, 2004
Summary
Human carcinoid BON cells secrete serotonin (5-HT). Acetylcholine stimulates 5-HT release via a somatostatin-sensitive pathway, while calcium and barium ions also trigger secretion, revealing slow vesicle dynamics.
Area of Science:
- Neuroendocrinology
- Cell Biology
- Pharmacology
Background:
- BON cells are human carcinoid cells known to secrete serotonin (5-HT) and peptides.
- Understanding the regulation of 5-HT secretion is crucial for carcinoid tumor research.
Purpose of the Study:
- To investigate the mechanisms regulating serotonin secretion in BON cells.
- To analyze the kinetics and dynamics of secretory vesicle exocytosis at the single-cell level.
Main Methods:
- Radioactive [(3)H]5-HT secretion assays in cell cultures.
- Stimulation with acetylcholine, isoproterenol, Ca(2+)/ionophore A-23187, digitonin, and Ba(2+).
- Single-cell analysis using carbon fiber amperometry and evanescent-field fluorescence microscopy with NPY-GFP labeled vesicles.
Main Results:
- Acetylcholine (Ach) stimulated [(3)H]5-HT secretion via a somatostatin-sensitive muscarinic pathway.
- Ca(2+)-dependent secretion (ionophore or permeabilization) and Ba(2+)-induced secretion were observed, with the latter being somatostatin-sensitive.
- Single-cell imaging revealed slow secretory response kinetics and vesicle arrest periods before exocytosis, indicating a regulated docking/priming step.
Conclusions:
- Serotonin secretion in BON cells is regulated by distinct pathways, including somatostatin-sensitive and insensitive mechanisms.
- The exocytosis process involves slow kinetics and a significant docking/priming phase before vesicle fusion.