Kolesistokinin

Kolesistokinin, known in English as cholecystokinin (CCK), is a peptide hormone and neuropeptide produced primarily by I cells in the mucosa of the duodenum and proximal jejunum. It exists in several active forms, including CCK-58, CCK-33, CCK-22, and CCK-8, which are generated by enzymatic processing of the larger precursor, preprocholecystokinin. The sulfated forms of CCK are the most biologically active and are important for receptor binding.

Release of CCK is stimulated by the presence of fatty acids and small peptides in the lumen of the small intestine. Once released, CCK acts on both peripheral organs and the brain, mediating digestion and feeding-related responses. The actions are carried out through specific receptors, primarily two subtypes: CCK1 (CCK-A) and CCK2 (CCK-B). CCK1 receptors are abundant in the pancreas and gallbladder and promote exocrine enzyme secretion and gallbladder contraction, while CCK2 receptors are common in the brain and gastric mucosa and can influence gastric acid secretion and neural pathways.

Physiological roles of CCK include stimulation of pancreatic enzyme secretion from acinar cells, contraction of the gallbladder leading to bile release, and slowing of gastric emptying to optimize digestion. It also contributes to the sensation of satiety and can modulate neuronal processes related to anxiety and pain. In clinical and research contexts, CCK and its receptors are studied as targets for disorders involving digestion, satiety, and appetite regulation.