The Pancreatic Polypeptide (PP-Fold) Family: Gastrointestinal, Vascular, and Feeding Behavioral Implications

Abstract

istorical Background. Of the four recognized peptide hormones secreted by the endocrine pancreas, pancreatic polypeptide (PP) was the third to be discovered, isolated, and characterized. Insulin ( 192 1-22) and glucagon ( 1923) preceded and somatostatin ( 1975) followed the isolation of PP in 1968. Despite this sequence of events-and the time interval since its discovery-PP remains somewhat of an enigma both in name and in function. The reluctance to label this polypeptide with a more descriptive title than the lackluster PP it bears stems largely from the fact that while broad actions may be attributed to it, no outstanding or dominating effect has been identified with its actions. Thus, the only characteristic carried by use of the phrase PP is to signify the species of PP one is discussing, such as avian, bovine, rat, porcine, ovine, and human, for example. The avian structure has 15 identities (of a total of 36) with that of bovine PP, and the latter differs by one or two residues from most other mammalian PP at any of three or four positions within the molecule. Thus, strong structural conservatism exists from an evolutionary point of view.The consideration that a family of pancreatic polypeptides exists is not unique within the field of physiologic chemistry, as it has been well recognized that many other polypeptides of interest are structurally related, are well conserved, and have overlapping physiological actions, and yet also may express distinctly ' To whom requests for reprints should be addressed

The role of pancreatic polypeptide in pancreatic diseases

“…Hypoglycemia, during which the muscarinic acetylcholine receptors and, to a lesser extent, adrenergic receptors are activated, also has an influence on PP release. 10 PP is released into the plasma during after-meal stimulation, in particular in the case of meals containing protein and fat. Its physiological role includes gastric stimulation inhibition, gastric acid secretion stimulation, delayed gastric emptying (Fig.…”

Differences in the expression of xenobiotic-metabolizing enzymes between islets derived from the ventral and dorsal anlage of the pancreas

“…For yet unexplained reasons, the islets in the uncinate process, which derives from the ventral anlage, contain more PP cells and less glucagon cells compared to the areas derived from the dorsal anlage (i.e. the body and tail of the organ) [20][21][22][23][24][25].…”

Pancreatic polypeptide in obese children before and after weight loss

“…12 In humans, administration of pharmacological doses of PP has also been shown to decrease food intake over the following 24 h. 13,14 Furthermore, PP inhibits gastric emptying rate, exocrine pancreatic secretion and gallbladder motility. 15 In obese humans, studies concerning PP values have demonstrated conflicting results. Some studies found no difference between lean and obese subjects, [16][17][18] whereas other studies demonstrated lower fasting PP levels in obese subjects.…”