Chromogranin-B regulation of IAPP and insulin secretion

In the endocrine pancreas, chromogranin-il and pancreastatin have been sugg ested to inhibit islet insulin secretion, whereas chromogranin-B has not be en studied in this context. Furthermore, a putative effect by chromogranins on IAPP secretion is unknown. We aimed to elucidate the endogenous effect of chromogranin-h, pancreastatin and chromogranin-B on islet insulin and IA PP secretion from pancreatic NMRI mouse islets. In acute experiments, there was a tendency towards an increase in insulin release, which became more m anifest after a 48-h exposure. Moreover, 48 h exposure to chromogranin-B an tiserum resulted in a significant increase in (pro)insulin synthesis. Neith er antibodies against chromogranin-A nor pancreastatin had any effect on is let hormone secretion. None of the antibodies tested had any effect on isle t IAPP or insulin content. We suggest that chromogranin-B released from isl ets may have an autocrine inhibitory effect on islet IAPP and insulin secre tion. Our data imply a regulatory role of chromogranin-B in islet IAPP and insulin secretion. (C) 2000 Elsevier Science B.V. All rights reserved.