Cholecystokinin and the hormone concept

Abstract

The birth certificate for endocrinology was Bayliss’ and Starlin g’s demonstration in 1902 that regulation of bodily functions is not only neuronal but al so due to blood-borne messengers. Starling named these messengers hormones. Since the n transport via blood has defined hormones. This definition, however, may be too narrow . Thus, today we know that several peptide hormones are not only produced and re leased to blood from endocrine cells but also released from neurons, myocytes, immun e cells, endothelial cells, spermatogenic cells, fat cells, etc. And they are often secreted in cell-specific molecular forms with more or less different spectra of activity. The present review depicts this development with the story about cholecystokinin which was discovered in 1928 as a hormone and still in 1976 was conceived as a single blood- borne peptide. Today’s multifaceted picture of cholecystokinin suggests that time may be ripe for expansion of the hormone concept to all messenger molecules, which activa te their target cells – irrespective of their road to the target (endocrine, neurocri ne, neuronal, paracrine, autocrine, etc.) and irrespective of their kind of activity as classical hormone, growth factor, neurotransmitter, adipokine, cytokine, myokine, or fertility factor.

Keywords

• cholecystokinin
• bioactive peptides
• hormone concept
• growth factors
• neurotransmitter peptides