Circadian variations in plasma concentrations of cholecystokinin and gastrin in man

Abstract

Cholecystokinin (CCK) is a gut hormone which regulates gallbladder contraction and pancreatic enzyme secretion. In addition, CCK is also a major intestinal satiety signal. The knowledge about CCK in circulation, however, has been limited by difficulties in accurate measurement of the concentrations in plasma. Thus, CCK circulates in low concentrations and furthermore, it is structurally homologous to the antral hormone, gastrin, which circulates in higher concentrations. Therefore, most antibodies raised against CCK cross-react in immunoassays with gastrin. However, using highly sensitive and entirely specific in-house radioimmunoassays, which meet these challenges, we have now measured the daily concentration-variations of CCK and gastrin in plasma from young healthy men (n = 24). Plasma was sampled every third hour from each person during 24 h. The results show that the gastrointestinal secretion of both CCK and gastrin in man display significant circadian variations.

Keywords:

• Cholecystokinin (CCK)
• diagnosis
• circadian variation
• gastrin
• immunoassay specificity

Acknowledgements

The skillful technical assistance of Louise Skifter Larsen, and the skillful secretarial assistance of Connie Bundgaard (MA) are gratefully acknowledged.

Disclosure statement

No conflict of interest was reported by the author(s).

Additional information

Funding

The study was supported by grants from the Danish State Biotechnology ‘Center for Cellular Communication’.