A gastrointestinal hormone and neuropeptide; regulates secretion from the stomach, pancreas, and liver; dose-dependently increases somatostatin release from primary human antral cells in vitro; dose-dependently increases the volume of pancreatic secretion in rats; inhibits gastrin I-induced gastric acid secretion in rats at 100 pmol/kg per h; increases the number of neurons expressing c-fos in the central amygdala and area postrema of rats at 40 μg/kg