CCK-8 (Cholecystokinin Octapeptide)

Cholecystokinin (CCK) is one of the most important hormone regulators of the digestive process. The peptide is concentrated in the proximal small intestine (CCK cells) and is secreted into the blood in response to the ingestion of proteins and fats, where its actions include the stimulation of pancreatic secretion, the modulation of insulin output, the regulation of gastric emptying, and gallbladder contraction. In the central nervous system CCKergic fibres are widespread, being particularly abundant in the cerebral cortex. In some mesolimbic neurons projecting to the nucleus accumbens, CCK is colocalised with dopamine and it has been suggested that CCK might facilitate the function of dopamine in events such as stimulusreward associative behaviour. Secretion of CCK from the murine tumour cell line STC1 has been shown to be stimulated by pituitary adenylate cyclase activating protein (PACAP) and has raised the possibility that PACAP may function as a neuromodulator of CCK release from gut endocrine cells in vivo. CCK-8 is also suspected to heighten pain sensation in diabetics.