Figure 4.

Ghrelin potentiates glucose-stimulated somatostatin secretion. A: Ghrelin significantly increases somatostatin release from mouse islets in vitro. B: Ghrelin, but not des-acyl-ghrelin, promotes somatostatin release. Astressin2b attenuates glucose-stimulated somatostatin release by preventing beta cell-derived Ucn3 from stimulating delta cells. Astressin2b does not prevent ghrelin from stimulating somatostatin release, indicating that ghrelin's actions are independent from the feedback mediated by Ucn3. C: Ghrelin, but not des-acyl-ghrelin, promotes glucose stimulated somatostatin secretion from human islets in vitro. D: Perfusion of mouse islets under high glucose with ghrelin (black circles) acutely potentiates glucose-stimulated somatostatin secretion compared to control (open circles). E: Application of des-acyl-ghrelin before and during stimulation does not affect the ability of ghrelin to potentiate glucose-stimulated somatostatin secretion. All mice were wild type, and all peptides were applied at 100 nM final concentration. Values represent the mean ± SEM for 8 (A), 7 (B) or 6 (C) wells per group (A–C) or 3 parallel perfusion chambers (D, E). *P < 0.05; **P < 0.01; ***P < 0.001.