Secretin, Cholecystokinin and Newer Gastrointestinal Hormones

New HormonesIn addition to the hormones already discussed, several polypeptides have recently been identified and physiologic phenomena observed suggesting that other substances may be involved with the initiation and modulation of the normal digestive process. These "candidate hormones," as Grossman153 , 154 calls them, include glucagon, gastric inhibitory polypeptide (GIP), vasoactive intestinal polypeptide (VIP), bombesin, motilin, chymodenin, bulbogastrone, entero-oxyntin and pancreatic polypeptide. Because somatostatin-like immunoreactivity has been found to be present in the gut,155 we have added it to the group.What makes a candidate hormone a true hormone? Grossman154 says,..., it must be shown that the peptide in question . . .