Kolekystokiniinin

Cholecystokinin, commonly abbreviated CCK, is a peptide hormone and neuropeptide that regulates digestion. In Polish contexts it is referred to as kolekystokinina, reflecting its widespread study in gastrointestinal physiology. In humans CCK is produced primarily by I cells in the mucosa of the duodenum and proximal jejunum and is released in response to nutrient-rich chyme, especially fats and amino acids. It exists in several molecular forms, with CCK-8 and CCK-33 being among the best characterized.

The main actions of CCK are to stimulate gallbladder contraction and bile release into the small intestine, stimulate pancreatic enzyme secretion from acinar cells, and slow gastric emptying to optimize digestion. In the central nervous system, CCK also acts as a neurotransmitter and neuromodulator, contributing to appetite regulation and satiety, as well as influencing anxiety and pain signaling.

Receptors and mechanism: CCK exerts its effects primarily through two G protein-coupled receptors, CCK1 (also known as CCK-A) and CCK2 (CCK-B). CCK1 receptors mediate most peripheral digestive actions, including gallbladder contraction and pancreatic secretion, while CCK2 receptors are more prominent in the brain and gastric tissues. The sulfated forms of CCK have higher affinity for CCK1.

Clinical and research relevance: CCK is used in diagnostic procedures such as CCK-cholescintigraphy to assess gallbladder function by measuring the gallbladder ejection fraction. Pharmacological modulation of CCK signaling has been explored in obesity and anxiety research, though no CCK-based therapies are standard for these conditions. The peptide is derived from the preprocholecystokinin gene and undergoes tissue-specific processing to yield active forms.