Cholecystokinin-8

Where it comes from

Made in

I cells of the duodenum and jejunum, and neurons throughout the brain

Sent out by

Fat and protein in the upper small intestine

Acts on

• Gallbladder
• Pancreatic acinar cells
• Vagus nerve
• Pyloric sphincter

What it does

• Contracts the gallbladder and releases pancreatic enzymes ¹
• Slows the emptying of the stomach
• Signals fullness through the vagus nerve ¹

In medicine

• Sincalide, synthetic CCK-8, is given to contract the gallbladder during imaging and to collect pancreatic juice ²
• CCK1 blockers (dexloxiglumide) were trialled for constipation-type IBS and dropped

Beyond the body’s own use

• CCK-8 reduces meal size in people, but the effect fades with repeated doses, which is why it was never developed as a weight-loss medicine ¹
• CCK-4, a four-residue fragment, brings on a panic attack within a minute of injection, and is used in the laboratory to test anti-anxiety drugs ¹