CCK-4

CCK-4

Cholecystokinin tetrapeptide (CCK-4, Trp-Met-Asp-Phe-NH2; also PTK7) is a peptide fragment derived from the larger peptide hormone cholecystokinin. Unlike cholecystokin which has a variety of roles in the gastrointenstinal system as well as central nervous system effects, CCK-4 acts primarily in the brain as an anxiogenic, 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 symptoms when administered to humans in a dose of as little as 50μg,[1] and is commonly used in scientific research to induce panic attacks for the purpose of testing new anxiolytic drugs.[2][3][4][5] 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,[6] although numerous synthetic analogues with modified properties are known.[7][8][9][10][11][12][13][14][15][16][17]

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