Pancreatic polypeptide ? A postulated new hormone: Identification of its cellular storage site by light and electron microscopic immunocytochemistry

Abstract

A peptide, referred to as pancreatic polypeptide (PP), has recently been isolated from the pancreas of chicken and of several mammals. PP is thought to be a pancreatic hormone. By the use of specific antisera we have demonstrated PP immunoreactivity in the pancreas of a number of mammals. The immunoreactivity was localized to a population of endocrine cells, distinct from the A, B and D cells. In most species the PP cells occurred in islets as well as in exocrine parenchyma; they often predominated in the pancreatic portion adjacent to the duodenum. In opossum and dog, PP cells were found also in the gastric mucosa. In opossum, the PP cells displayed formaldehyde - induced fluorescence typical of dopamine, whereas no formaldehyde-induced fluorescence was detected in the PP cells of mouse, rat and guinea pig. Also in these latter species, however, PP cells appear to possess amine-handling properties, a feature common to many peptide hormone-producing cells. The ultrastructure of the PP cells was defined by combining immunohistochemistry of semi-thin plastic sections with electron microscopy of adjacent ultrathin sections. PP cells show the ultrastructural features of peptide hormone-secreting cells. The PP cells of cat and dog contain fairly large, rather electron-lucent granules, and are probably identical with the previously described F cells. The PP cells of rat, guinea-pig, chinchilla and man contain small, fairly electron-dense granules. In these latter species no F cells are found. By immunoperoxidase staining of ultrathin sections, the PP immunoreactivity was found to be localized to the cytoplasmic granules. These observations provide support for the view that PP is a true pancreatic hormone.

GPR40 is expressed in glucagon producing cells and affects glucagon secretion

“…Furthermore, the relative abundance of different cell types may also vary depending on the location of the islet within the pancreas, as demonstrated for alpha-and PP-cells. Islets from the proximal (head) part of the rat pancreas contain relatively few alpha cells, but numerous PP-cells, whereas the relationship is reversed in the distal (tail) part [14,15]. Different isolation methods result in variable yields of islets and the origin of the islets will have a great influence on studies of e.g.…”

Hyperplasia of “pancreatic polypeptide”-cells in the pancreas of juvenile diabetics

“…"Pancreatic polypeptide" is a 36-aminoacid peptide which has been isolated from the avian pancreas [9,10] and from the pancreas of several mammals, including man [11,12,13,14]. Cells containing "pancreatic polypeptide" have been demonstrated in the pancreas of chicken [21] and of a variety of other species [22,23,24]. Their ultrastrucrural characteristics have not been clearly defined, but Larsson et al [23] suggested that they correspond to the type V-cells of Deconinck et al [25].…”

“…Cells containing "pancreatic polypeptide" have been demonstrated in the pancreas of chicken [21] and of a variety of other species [22,23,24]. Their ultrastrucrural characteristics have not been clearly defined, but Larsson et al [23] suggested that they correspond to the type V-cells of Deconinck et al [25].…”

Ontogeny of Cells Containing Insulin, Glucagon, Pancreatic Polypeptide Hormone and Somatostatin in the Bovine Pancreas

“…Glucagon, PP and somatostatin have also been demonstrated in cells of extra-pancreatic tissue such as those of the gastrointestinal tract (Hokfelt et al 1975;Larsson et al 1976;Leduque et al 1982) and more recently insulin-like material has been reported to be present in the brain (Baskin et al 1983;Birch et al 1984). A number of biologically active peptides previously found in the hypothalamus and other regions of the brain have now been shown to exist in the pancreatic islet.…”