Ontogenic development of peptide hormones in the mammalian fetal pancreas

Summary The ontogeny of insulin, glucagon, PP and somatostatin in the mammalian fetal pancreas has been examined in recent years largely by immunocytochemistry and in some instances by radioimmunoassay. Complete ontogenic data are available only for the rat, human pig and sheep. Figure 3 compares the time of appearance of the endocrine cell-types within the fetal pancreas when the periods of gestation of the four species are converted to a uniform scale. The striking ontogenic difference in the rat probably reflects the immaturity of the rodent fetus at birth compared with the human, pig and sheep. In the fetal pancreas, differences in cell number of glucagon and PP cells in the dorsal and ventral lobes become apparent from an early gestational period. Factors responsible for the functional and structural maturation of the fetal pancreatic endocrine cells and the processes involved in pancreatic organogenesis are poorly understood. Studies in these areas would have clinical implications since it may be possible in the future to employ agents for selective replication of fetal -cells for transplantation in patients with Type I diabetes, bearing in mind that such cells must have the capacity to respond to normal stimuli and repressors when transplanted. The presence of the other islet cell-types may be obligatory for these appropriate responses. This would require a more complete knowledge of those factors which produce the normal selectivity of the four hormonal cell-types.     

Preliminary observations on the co-existence of regulatory peptides in cells of the baboon endocrine pancreas

Summary Immunocytochemical procedures at ultrastructural and light microscopy level revealed, in the Chacma baboon endocrine pancreas, cells which were immunoreactive for glucagon and pancreatic polypeptide (PP). Some D cells were observed to contain secretory granules with both the appearance and immunoreactivity of A cell secretory granules.     

Preliminary observations on the co-existence of regulatory peptides in cells of the baboon endocrine pancreas

Immunocytochemical procedures at ultrastructural and light microscopy level revealed, in the Chacma baboon endocrine pancreas, cells which were immunoreactive for glucagon and pancreatic polypeptide (PP). Some D cells were observed to contain secretory granules with both the appearance and immunoreactivity of A cell secretory granules.     

Co-localization of glucagon and pancreatic polypeptide in testudine pancreas

Summary Immunocytochemistry was carried out on sections of pancreas from the gopher tortoise,Gopherus polyphemus. Combined immunofluorescent and peroxidase-anti-peroxidase techniques showed unequivocally that some of the cells were immunoreactive for both glucagon and pancreatic polypeptide (PP). Antibodies directed against avian PP, bovine PP, and human PP all have a positive reaction. Co-localization of glucagon and PP in the pancreas of the gopher tortoise indicates that the occurrence of these hormones in the same cells is widespread in higher vertebrates.Acknowledgments. This work was supported in part by grants from the University of Cape Town, the M. Crossley bequest, the N. Atkinson bequest, and Herman and Caporn bequests. The generous gifts of antisera by Dr Chance and the late Dr Kimmel, and the gift of hormones by the Lilly Research Laboratories are gratefully acknowledged. The excellent technical assistance of J. Thompson and J. B. De Haan is also gratefully acknowledged. Please send all correspondence to the USA address.     

Glucagon and pancreatic polypeptide immunoreactivities co-exist in a population of rat islet cells

In mammalian pancreas, glucagon and pancreatic polypeptide have been shown to be present in distinct cell types. The present communication reports that, in rat pancreas, in addition to glucagon and pancreatic polypeptide cell populations, there is a small population of cells which contain both glucagon and pancreatic polypeptide immunoreactivities.     

Glucagon and pancreatic polypeptide immunoreactivities co-exist in a population of rat islet cells

Summary In mammalian pancreas, glucagon and pancreatic polypeptide have been shown to be present in distinct cell types. The present communication reports that, in rat pancreas, in addition to glucagon and pancreatic polypeptide cell populations, there is a small population of cells which contain both glucagon and pancreatic polypeptide immunoreactivities.     

Endocrine cells producing regulatory peptides

Recent data on the immunolocalization of regulatory peptides and related propeptide sequences in endocrine cells and tumors of the gastrointestinal tract, pancreas, lung, thyroid, pituitary (ACTH and opioids), adrenals and paraganglia have been revised and discussed. Gastrin, xenopsin, cholecystokinin (CCK), somatostatin, motilin, secretin, GIP (gastric inhibitory polypeptide), neurotensin, glicentin/glucagon-37 and PYY (peptide tyrosine tyrosine) are the main products of gastrointestinal endocrine cells; glucagon, CRF (corticotropin releasing factor), somatostatin, PP (pancreatic polypeptide) and GRF (growth hormone releasing factor), in addition to insulin, are produced in pancreatic islet cells; bombesin-related peptides are the main markers of pulmonary endocrine cells; calcitonin and CGRP (calcitonin gene-related peptide) occur in thyroid and extrathyroid C cells; ACTH and endorphins in anterior and intermediate lobe pituitary cells, alpha-MSH and CLIP (corticotropin-like intermediate lobe peptide) in intermediate lobe cells; met- and leu-enkephalins and related peptides in adrenal medullary and paraganglionic cells as well as in some gut (enterochromaffin) cells; NPY (neuropeptide Y) in adrenaline-type adrenal medullary cells, etc.. Both tissue-appropriate and tissue-inappropriate regulatory peptides are produced by endocrine tumours, with inappropriate peptides mostly produced by malignant tumours.     

Endorcine cells producing regulatory peptides

Summary Recent data on the immunologication of regulatory peptides and related propeptide sequences in endocrine cells and tumours of the gastrointestinal tract pancreas, lung, thyroid, pituitary (ACTH and opioids), adrenals and paraganglia have been revised and discussed. Gastrin, xenopsin, cholecystokinin (CCK), somatostatin, motilin, secretin, GIP (gastric inhibitory beenrevised and discussed. Gastrin, xenopsin, cholecystokinin (CCK), somatostatin, motilin, secretin, GIP (gastric inhibitory polypeptide), neurotensin, glicentin/glucagon-37 and PYY (peptide tyrosine tyrosine) are the main products of gastrointestinal endocrine cells; glucagon, CRF (corticotropin releasing factor), somatostatin, PP (pancreatic polypeptide) and GRF (growth hormone releasing factor), in addition to insulin, are produced in pancreatic islet cells; bombesin-related peptidesare the main markers of pulmonary endocrine cells; calcitonin and CGRP (calcitonin gene-related peptide) occur in thyroid and extrathyroid C cells; ACTH and endorphins in anterior and intermediate lobe pituitary cells, -MSH and CLIP (corticotropoin-like intermediate lobe peptide) in intermediate lobe cells; met- and leu-enkephalins and related peptides in adrenal medullary and paraganglionic cells as well as in some gut (enterochromaffin) cells; NPY (neuropeptide Y) in adrenalin-type adrenal medullary cells, etc.. Both tissue-appropriate and tissue-inappropriate regulatory peptides are produced by endocrine tumours, with inappropriate peptides mostly produced by malignant tumours.     

The islet-acinar axis of the pancreas: Is there a role for glucagon or a glucagon-like peptide?

Intravenous glucagon inhibits exocrine pancreatic secretion in vivo, but exogenous glucagon does not affect exocrine secretion in vitro. Recent work, however, suggested that endogenous glucagon may be involved in the regulation of exocrine secretion even in vitro. We therefore investigated the effects of exogenous and endogenous glucagon on exocrine secretion by the isolated perfused rat pancreas in the presence of 1.8 mM glucose. Exogenous glucagon did not affect CCK-stimulated amylase output. 20 mM arginine stimulated glucagon release, but did not affect basal enzyme secretion. CCK-stimulated amylase output, however, was significantly inhibited in the presence of arginine. This inhibitory effect of arginine on exocrine pancreatic secretion could be blocked by glucagon antibodies, but not by nonspecific gammaglobulins. Thus exogenous glucagon failed to affect exocrine pancreatic secretion in vitro, but endogenously released glucagon or a glucagon-like peptide inhibited amylase release in the isolated perfused pancreas. We conclude that glucagon or a glucagon-like peptide may be a mediator in the islet-acinar axis.     

Endocrine and exocrine pancreatic function after camostate-induced growth of the organ

It is well known that oral administration of camostate induces hyperplasia and hypertrophy of the rat pancreas. It is not clear, however, whether pancreatic hormone and enzyme secretion are affected by camostate treatment.In rats, daily administration of 200 mg camostate/kg b. wt for 14 days significantly increased pancreatic weight and pancreatic content of DNA, protein, amylase, lipase, trypsin and chymotrypsin, as well as the amount of insulin, glucagon and somatostatin. In the intact animal, blood glucose levels and serum concentrations of insulin and glucagon in response to an oral glucose load were not impaired after camostate treatment. In the isolated perfused pancreas, however, insulin and glucagon secretions were reduced, whereas somatostatin release was not affected. The volume of pancreatic juice produced by the unstimulated isolated perfused organ, as well as protein and enzyme secretion, were increased after camostate treatment. Likewise, the isolated perfused pancreas from camostate-treated rats secreted a larger volume of pancreatic juice and more protein in response to cholecystokinin (CCK), while enzyme secretion was affected in a non-parallel manner: amylase release was markedly reduced, lipase release was unchanged, and release of trypsin and chymotrypsin was increased.     

Secretion of insulin and of glucagon by the perfused pancreas of newborn rats: effect of vasoactive intestinal peptide Vip]

A method is described for perifusion of the splenic part of the pancreas from 48-64 hour-old rat. In different basal conditions, the secretion of insulin and glucagon is stable and reproducible for 90 mn. The addition of the vasoactive intestinal peptide (VIP) to these perifusion media, at a concentration as low as 2 ng/ml, determines a remarkable increase of insulin and of glucagon secretion. These results suggest the possibility of a VIP action in the physiology of endocrine pancreas.     

Bombesin-like immunoreactivity in the pancreas of man and other mammalian species

Summary Bombesin-like immunoreactivity has been measured in pancreatic tissues of man (12.4±1.2 pmol/g), pig (15.8±3.2), calf (4.3±0.9), rat (8.5±1.2) and guinea-pig (2.8±0.6) by a specific radioimmunoassay. Gel filtration of the pancreatic extracts revealed 2 major immunoreactive peaks: the earlier peak was eluted in the position of porcine gastrin-releasing peptide, and the later peak was eluted just after the amphibian bombesin standard. Immunocytochemistry demonstrated the presence of bombesin-like immunoreactivity in nerves in the rat pancreas, particularly in the exocrine pancreas, and occasionally in the peri-insular spaces. Isolated rat pancreatic islets were found to contain small quantities of bombesin-like immunoreactivity (0.037±0.003 fmol/islet) suggesting that mammalian bombesin-like peptides may be invovled in the regulation of endocrine as well as exocrine pancreatic secretion.Acknowledgments. We are grateful to Dr. A. V. Edwards, Physiological Laboratory, Cambridge, U. K. for providing the calf tissues, and the British Diabetic Association, U. K. for support.To whom reprint requests should be addressed.     

Presence of "pancreatic polypeptide" cells, and gastrin immunoreactivity in immuno-induced exocrine pancreas carcinoma]

1) In electively immuno-induced carcinomas of the exocrine pancrease in Mice, where A (glucagon) and B (insulin) endocrine cells persist, cells with a pancreatic polypeptide immunoreactivity are also detected, even in late evolution stages. These cells, like D cells, containing somatostatin, are localized only in the pancreatic remains surrounding the anaplasic carcinomatous tissue: islets, adenomatous parenchyma, and ductular epithelium. Ultrastructure of these cells shows their active elaboration of numerous chracteristic secretion granules. (2) Immunocytoenzymatic detection of gastrin is negative in the exocrine and endocrine pancreatic tissues. However one of the anti-gastrin sera used gives a positive reaction, in some carinomatous cells only. Does this immunoreactivity characterize a polypeptide specific to the pancreatic carcinomatous cell?     

Regional distribution of pancreatic polypeptide cells in the 21-day fetal rat pancreas

Summary 21-day fetal rat pancreata were stained with the unlabeled antibody peroxidase-antiperoxidase technique using bovine pancreatic polypeptide as the primary antibody. Total counts of pancreatic polypeptide cells were made over the entire pancreas. It was found that the head region contained the greatest number of pancreatic polypeptide cells with the body next and the tail having the smallest number. The pancreatic polypeptide cells of the body were concentrated in the portion closest to the distal duodenum. This distribution pattern seems to support the suggested role of pancreatic polypeptide on the physiological function of the digestive tract.The authors wish to express their appreciation to Dr R. McEvoy, T. Whittlsey, G. Wassilchenko and D. Wilson for their assistance in this study. To whom reprint requests should be addressed.     

Immunofluorescent demonstration of pancreatic polypeptide (PP) in pancreas and digestive tube of bony and cartilaginous fish]

When antisera specific against bovine PP (BPP) were used, immunoreactive parenchymal cells were observed in the endocrine pancreas and in the gastro-intestinal tract of the teleost bony fish Cottus scorpius, as well as in the pancreas of the elasmobranchian cartilaginous fish Squalus acanthias. Of the two principal islets of Cottus, PP-cells were located selectively to that in the pyloric region.     

Demonstration of tissue-specific antigens shared by normal pancreas and pancreatic neoplasms

Summary Xenoantiserum raised against extracts of normal hamster pancreas, after absorption with normal tissues, reacted specifically with normal hamster and human pancreas by immunodiffusion. Absorbed antiserum also reacted with hamster and human pancreatic carcinoma but not with other neoplasms. Immunization of hamsters with normal pancreas extracts prevented growth of transplantable pancreatic carcinomas.     

Demonstration of tissue-specific antigens shared by normal pancreas and pancreatic neoplasms

Xenoantiserum raised against extracts of normal hamster pancreas, after absorption with normal tissues, reacted specifically with normal hamster and human pancreas by immunodiffusion. Absorbed antiserum also reacted with hamster and human pancreatic carcinoma but not with other neoplasms. Immunization of hamsters with normal pancreas extracts prevented growth of transplantable pancreatic carcinomas.     

Pancreatic polypeptide: A possible role in the regulation of food intake in the mouse. Hypothesis

Summary Pancreatic polypeptide (PP) is a recently identified hormone produced by pancreatic endocrine cells. The islets of genetically obese mice (ob/ob, C57 BL/6J), which are suspected to lack a circulating satiety factor, contain relatively few of the PP-producing cells. Administration of bovine pancreatic polypeptide (bPP) reduces food intake and suppresses body weight gain in the hyperphagic obese mice. It is postulated that PP participates in the regulation of food intake in a manner as yet undefined.This work was supported by grant No. 3.553.75 from Swiss National Science Foundation. We thank Mrs M. Eissler and Mr R. Cuche for their valuable help.