Effect of cysteamine on insulin release and exocrine pancreatic secretion in vitro.

Cysteamine is known to deplete somatostatin from pancreatic D cells. In the isolated perfused rat pancreas we investigated its effects on somatostatin and insulin release as well as exocrine pancreatic secretion in the presence of 16.7 mM glucose and 180 pM CCK-8. At a concentration of 0.1 mM, cysteamine had no significant effect on pancreatic endocrine and exocrine functions. At 10 mM, however, cysteamine released somatostatin (380 +/- 70 vs 100 +/- 20 fmol/20 min), inhibited insulin output (890 +/- 120 vs 13210 +/- 3260 mu units/20 min) and reduced exocrine pancreatic secretion (volume: 12 +/- 2 vs 20 +/- 2 microliters/20 min; lipase: 31 +/- 3 vs 60 +/- 7 units/20 min). We conclude that the complex changes induced by cysteamine are consistent with a physiological role of endogenous somatostatin in the regulation of insulin release. The reduction of exocrine pancreatic secretion, however, was at least in part, if not completely, mediated via the insuloacinar axis rather than a direct effect of cysteamine-released somatostatin on pancreatic acinar cells.