Regulation of amylin release from cultured rabbit gastric fundic mucosal cells.
BACKGROUND
Amylin (islet amyloid polypeptide) is a hormone with suggested roles in the regulation of glucose homeostasis, gastric motor and secretory function and gastroprotection. In the gastric mucosa amylin is found co-localised with somatostatin in D-cells. The factors regulating gastric amylin release are unknown. In this study we have investigated the regulation of amylin release from gastric mucosal cells in primary culture. Rabbit fundic mucosal cells enriched for D-cells by counterflow elutriation were cultured for 40 hours. Amylin and somatostatin release over 2 hours in response to agonists were assessed.


RESULTS
Amylin release was significantly enhanced by activation of protein kinase C with phorbol-12-myristate-13-acetate, adenylate cyclase with forskolin and elevation of intracellular calcium with A23187. Cholecystokinin (CCK), epinephrine and glucagon-like peptide-1 (GLP-1) each stimulated amylin release in a dose-dependent manner. Maximal CCK-stimulated release was greater than either epinephrine or GLP-1, even when the effects of the latter two were enhanced by isobutylmethylxanthine. Stimulated amylin release was significantly inhibited by carbachol (by 51-59%) and octreotide (by 33-42%). Somatostatin release paralleled that of amylin.


CONCLUSIONS
The cultured D-cell model provides a means of studying amylin release. Amylin secretion is stimulated by receptor-dependent and -independent activation of Ca2+/protein kinase C and adenylate cyclase pathways. Inhibition involves activation of muscarinic receptors and auto-regulation by somatostatin.
Beales
Ian L P
IL
Gastrointestinal Research Unit, Department of Physiology and Cell Biology, School of Medicine, Health Policy and Practice, University of East Anglia, Norwich NR4 7TJ, United Kingdom. i.beales@uea.ac.uk
Calam
John
J
D000262:Adenylyl Cyclases / Q000502:physiology; D000682:Amyloid / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D002766:Cholecystokinin / Q000502:physiology; D005748:Gastric Fundus / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005753:Gastric Mucosa / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D006706:Homeostasis / Q000502:physiology; D058228:Islet Amyloid Polypeptide; D015282:Octreotide / Q000494:pharmacology; D011493:Protein Kinase C / Q000502:physiology; D011817:Rabbits; D011949:Receptors, Cholecystokinin / Q000502:physiology; D013004:Somatostatin / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology; D019864:Somatostatin-Secreting Cells / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism
D000682:Amyloid; D058228:Islet Amyloid Polypeptide; D011949:Receptors, Cholecystokinin; D013004:Somatostatin; D002766:Cholecystokinin; D011493:Protein Kinase C; D000262:Adenylyl Cyclases; D015282:Octreotide