Cholecystokinin CCK

Definition and Functions

Cholecystoquine (CCK) is a gastrointestinal hormone of a protein nature involved in the homeostasis of digestive processes.

Composed of 33 amino acids and secreted mainly from the proximal portion of the small intestine (duodenum and jejunum), cholecystokinin:

• stimulates the secretion of a pancreatic juice rich in digestive enzymes;
• promotes relaxation of the sphincter of Oddi (the "door" that regulates the passage of bile and pancreatic juice in the "intestine);
• stimulates the contraction and emptying of the gallbladder (gallbladder);
• promotes the motility of the small intestine and colon;
• represents an important sign of satiety.

Food and Cholecystokinin

Effects of food on CCK secretion

The secretion of cholecystokinin is stimulated by fats and proteins from the chyme (pulp of partially digested food that comes out of the stomach). This is why a high-fat meal exerts a strong satiating power.

Not surprisingly, cholecystokinin stimulates bile secretion, essential for lipid digestion; high levels of this hormone in circulation signal to the organism that a large quantity of fat has been introduced and that - due to the high energy power of these nutrients - it is not necessary to consume additional quantities of food.

Furthermore, cholecystokinin signals the stomach to slow down its emptying, in order to leave the small intestine the time it needs to complete the digestion of fats and proteins in the best possible way.

Somatostatin exerts an inhibitory effect on the secretion of cholecystokinin, which is also progressively reduced by the decrease in the flow of fats and proteins from the gastric pylorus to the duodenum.

Stimulus test

Stimulus test for secretin and cholecystokinin

It is used in diagnostics to investigate the health of the pancreas. It is based on the intravenous injection of secretin and cholecystokinin (CCK) and on the subsequent evaluation of the quality of aspirated pancreatic secretion.