Cholecystokinin (CCK)
A peptide hormone produced by intestinal I-cells after eating that stimulates gallbladder contraction, pancreatic enzyme secretion, and satiety. Sincalide is a synthetic analogue of CCK used diagnostically to stimulate gallbladder contraction for imaging studies.
Technical Context
CCK exists in multiple forms (CCK-8, CCK-33, CCK-58) produced by intestinal I-cells and neurons. It acts on CCK-A (alimentary, primarily peripheral) and CCK-B (brain) receptors. CCK-A activation stimulates gallbladder contraction, pancreatic enzyme secretion, and satiety. CCK-B activation modulates anxiety and pain pathways. Sincalide (the C-terminal octapeptide of CCK, CCK-8) is used diagnostically to stimulate gallbladder contraction for hepatobiliary imaging (cholescintigraphy) — injection of sincalide causes gallbladder ejection, and the ejection fraction is measured to diagnose biliary dyskinesia. CCK is also relevant to understanding the complex gut hormone network that regulates appetite alongside GLP-1, GIP, PYY, and ghrelin.