Model for regulation of CCK release by an intraluminal releasing factor

A luminal cholecystokinin (CCK) releasing factor (LCRF) stimulates intestinal CCK secretion. LCRF is normally secreted in the intestinal lumen, where it is exposed to pancreatic enzymes, such as trypsin. Under basal conditions, LCRF is inactivated by even small amounts of pancreatic enzymes. However, following a meal, food competes for enzyme binding, allowing LCRF to interact with CCK cells to stimulate hormone secretion. CCK in the circulation stimulates pancreatic secretion that, upon digestion of food, restores LCRF and CCK secretion to basal levels.