Cholecystokinin tetrapeptide (CCK-4, Trp- Met- Asp- Phe-NH₂) is a

peptide Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. ...

fragment derived from the larger peptide hormone

cholecystokinin Cholecystokinin (CCK or CCK-PZ; from Greek ''chole'', "bile"; ''cysto'', "sac"; ''kinin'', "move"; hence, ''move the bile-sac (gallbladder)'') is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat an ...

. Unlike cholecystokin which has a variety of roles in the gastrointestinal system as well as

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...

effects, CCK-4 acts primarily in the brain as an

anxiogenic An anxiogenic or panicogenic substance is one that causes anxiety. This effect is in contrast to anxiolytic agents, which inhibits anxiety. Together these categories of psychoactive compounds may be referred to as anxiotropic compounds. Anxiogeni ...

, although it does retain some GI effects, but not as much as CCK-8 or the full length polypeptide CCK-58. CCK-4 reliably causes severe

anxiety Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil Turmoil may refer to: * ''Turmoil'' (1984 video game), a 1984 video game released by Bug-Byte * ''Turmoil'' (2016 video game), a 2016 indie oil tycoon video ...

symptoms when administered to humans in a dose of as little as 50μg, and is commonly used in scientific research to induce

panic attack Panic attacks are sudden periods of intense fear and discomfort that may include palpitations, sweating, chest pain or chest discomfort, shortness of breath, trembling, dizziness, numbness, confusion, or a feeling of impending doom or of losing ...

s for the purpose of testing new

anxiolytic An anxiolytic (; also antipanic or antianxiety agent) is a medication or other intervention that reduces anxiety. This effect is in contrast to anxiogenic agents which increase anxiety. Anxiolytic medications are used for the treatment of anxie ...

drugs. Since it is a peptide, CCK-4 must be administered by injection, and is rapidly broken down once inside the body so has only a short duration of action, although numerous synthetic analogues with modified properties are known.

References

{{Reflist Cholecystokinin agonists Tetrapeptides Anxiogenics Thioethers

See also

References