Cholecystokinin
Cholecystokinin (CCK) is a hormone found in the human body. It is secreted from the duodenum of the small intestine. CCK is composed of varying numbers of amino acids, and it is considered a peptide hormone.
Secretion and Production
CCK is produced in and secreted from the duodenum of the small intestine. It is primarily responsible for stimulating the digestion of fat and protein. When secreted, CCK causes the release of digestive enzymes from the pancreas and bile from the gallbladder. CCK acts as a hunger suppressant. Additionally, recent research suggests that CCK plays a role in inducing drug tolerance to opiates like morphine and heroin, and it has been implicated in the experience of pain hypersensitivity during opiate withdrawal.
CCK is secreted when fat and protein-rich chyme leave the stomach and enter the duodenum. CCK then causes the release of the pancreas enzymes lipase, amylase, trypsin, and chymotrypsin. These enzymes work together to digest fat, protein, and carbohydrates. CCK also stimulates the contraction of the gall bladder and the relaxation of the Sphincter of Oddi, resulting in the delivery of bile into the small intestine. Bile works to emulsify fats, therefore aiding in the digestive and absorption process.
Pharmacological Uses
CCK has been synthesized, but it is not commonly used as a drug because its effects vary between individuals. In general, CCK administration causes nausea and anxiety, therefore decreasing hunger and desire to eat. However, in studies performed on rats, CCK administration was less effective on females than males, less effective in older rats than younger ones, and less effective in obese rats than in those of average weight.