CCK-4

CCK-4 (Cholecystokinin tetrapeptide) is a peptide that is composed of four amino acids. It is a fragment of the larger protein cholecystokinin (CCK), which is involved in various physiological processes in the body, including the regulation of pancreatic enzyme secretion and gallbladder contraction, as well as the delay of gastric emptying.

Structure and Function

CCK-4 is a tetrapeptide with the sequence Trp-Met-Asp-Phe, which is derived from the larger CCK molecule. This peptide acts as an agonist at the CCK receptors, which are a type of G protein-coupled receptor found in the gastrointestinal tract and the central nervous system.

The binding of CCK-4 to these receptors triggers a cascade of intracellular signaling events, leading to various physiological responses. In the gastrointestinal tract, these responses include the secretion of digestive enzymes from the pancreas and the contraction of the gallbladder. In the central nervous system, CCK-4 is involved in the regulation of pain perception, anxiety, and satiety.

Clinical Significance

CCK-4 has been used in psychiatric research as a tool to induce panic attacks in humans. Studies have shown that the administration of CCK-4 can trigger panic attacks in individuals with panic disorder, but not in healthy controls. This has led to the suggestion that individuals with panic disorder may have an abnormal response to CCK-4.

In addition, research has indicated that CCK-4 may play a role in the pathophysiology of schizophrenia. Some studies have found that individuals with schizophrenia have altered levels of CCK-4 in their cerebrospinal fluid, suggesting that this peptide may be involved in the development of this disorder.

See Also

• Cholecystokinin
• Panic disorder
• Schizophrenia