Cholecystokinin

Cholecystokinin ( also known as CCK or CCK-PZ) is a peptide hormone of the gastrointestinal system which is responsible for stimulating the digestion of fat and protein. Cholecystokinin, previously called pancreozymin, is synthesized and secreted by enteroendocrine cells in the duodenum (the first portion of the small intestine) and leads to the release of bile and digestive enzymes. CCK also acts as an appetite suppressant and has been studied for weight management regimens ^L1637.

Normally, it is an endogenous hormone but is available commercially for diagnostic processes and replacement in pancreatic insufficiency L1646, L1647, L1648. in the octapeptide form.

Cholecystokinin is one of the first gastrointestinal hormones discovered, identified more than 90 years ago due to its ability to stimulate gallbladder contraction in 1928. Soon after, it was recognized to be identical to the factor responsible for stimulating pancreatic exocrine secretion in 1943 ^L1636. This hormone has also been shown to have positive effects on enteric smooth muscle contraction and on nerve activity at multiple locations in the peripheral and central nervous system. In addition to its roles in promoting smooth muscle cell contraction/exocrine cell secretion, CCK promotes cell growth, energy production, gene expression and protein synthesis, processes that have profound for drug development ^L1636. This drug has also been investigated for possible antipsychotic properties, owing to its effect on CCK receptors in the brain ^L1638.

Recent studies have suggested that cholecystokinin also plays a major role in inducing drug tolerance to opioids such as morphine and heroin, and is partially implicated in experiences of pain hypersensitivity during opioid withdrawal ^A32101.