boc-tyr(s03)-nle-gly-trp-nle-asp-2-phenylethyl-ester and big-gastrin

This study evaluated the role played by cholecystokinin (CCK) receptors' occupation in the control of somatostatin (SS) secretion in RIN-14B cells.. The presence of the CCK receptors 1 and 2 was confirmed by immunofluorescence, and SS secretion was evaluated by enzyme-linked immunosorbent assay.. By immunofluorescence, 95% of the cell population was composed of SS cells bearing both CCK-R subtypes with 5% of beta cells (data not shown). Cerulein (Cae), a CCK-1R agonist, and pentagastrin, a CCK-2R agonist, dose-dependently increased SS release, 3-fold at 1 mumol/L Cae, 2.5-fold at 10 mumol/L pentagastrin, with occupation of both CCKRs confirmed by L-364,178 and L-365,260 inhibition of CCK receptors 1 and 2. The occupation of high-affinity CCK-1R by Cae was confirmed on SS release with JMV-180, a high-affinity CCK-1R agonist, and absence of SS release inhibition at high Cae concentration occupying the low-affinity CCK-1R. These cells release more than 60% of their SS content by constitutive secretion, confirmed by cycloheximide and brefeldin inhibiting SS synthesis and intracellular trafficking, respectively.. Both CCKR subtypes occupy RIN-14B cells and initiate SS secretion through constitutive secretion controlled at SS synthesis level. Somatostatin secretion via the CCK-1R occupation mobilizes its high-affinity sites.

Topics: Animals; Benzodiazepinones; Brefeldin A; Cell Line; Ceruletide; Cholecystokinin; Cycloheximide; Devazepide; Dose-Response Relationship, Drug; Enzyme-Linked Immunosorbent Assay; Fluorescent Antibody Technique; Gastrins; Islets of Langerhans; Pentagastrin; Phenylurea Compounds; Protein Precursors; Protein Synthesis Inhibitors; Protein Transport; Rats; Receptor, Cholecystokinin A; Receptor, Cholecystokinin B; Sincalide; Somatostatin