Cholecystokinin- and secretin-releasing peptides in the intestine--a new regulatory interendocrine mechanism in the gastrointestinal tract.

Maintenance of homeostasis in the upper small bowel is a vital process for the body and therefore highly controlled. The enteric nervous system and the endocrine system are the regulators in this process influencing each other. The endocrine system in the gut consists of the classical hormones [cholecystokinin (CCK) secretin] to evoke motility or secretion. They are under control of releasing factors which are probably influenced by the enteric nervous system. Diazepam binding inhibitor and luminal CCK-releasing factor are likely candidates for CCK-releasing peptides in the negative feedback process in the absence of pancreatic juice. Experimental evidence suggests a secretin-releasing peptide. Further studies will be needed to determine the physiological role of each of these peptides. Monitor peptide in the pancreatic juice seems to function as a specific positive enhancement for CCK release. All these peptides are inactivated by the proteolytic enzymes during the interdigestive period. The discovery of additional releasing peptides and factors is very likely.