Ontogeny of cells containing insulin, glucagon, pancreatic polypeptide hormone and somatostatin in the bovine pancreas

Antibodies to insulin, glucagon, pancreatic polypeptide hormone (PP) and somatostatin were used in the immunofluorescence histochemical procedure to study the ontogeny of pancreatic endocrine cells containing the four hormones in the bovine fetus of approximately 100 days gestation to term. Pancreatic sections from the bovine neonate and adult were also examined for the cellular distribution of the four hormones. Immunoreactive cells staining for insulin, glucagon, PP and somatostatin were present in the pancreas of all fetuses studied. Each endocrine cell type displayed a characteristic distribution within the developing pancreas and in the neonate and adult. The presence of the four islet hormones relatively early in bovine fetal life suggests that they may be important in intra- and extra-islet metabolism in the fetus.     

Ontogeny of rat pancreatic polypeptide (PP) cells

Summary Cells storing pancreatic polypeptide (PP) appear in rat pancreas at the time of parturition, much later than insulin and glucagon cells. At this stage, the pancreatic polypeptide (PP) cells occur scattered in the exocrine parenchyma and in the islets. Subsequently, 5–7 days postnatally, an abrupt increase in the number of PP cells occurs. At this stage, they are fairly numerous in the islets and comparatively rare in the exocrine parenchyma. Not until 8–10 days after birth is the number of PP cells similar to that in the adult pancreas. A few PP cells were seen in the antral mucosa during the first 10 days after birth. They were not seen elsewhere in the gut.     

Histological and immunohistochemical studies of the endocrine pancreas of lizards

The endocrine pancreas of the grass lizard, Mabuya quinquetaenia-ta, and of the desert lizard, Uromastyx aegyptia, was investigated histologically and immunohistochemically. In both lizard species four cell types were observed in the endocrine pancreas, namely insulin (B), glucagon (A), somatostatin (D) and pancreatic polypeptide (PP) cells. In both species in B, A and D cells could be detected by their cross-reactivity with antisera raised against mammalian insulin, glucagon and somatostatin. However, these cells showed different tinctorial propertis in the two lizard species. In both species the endocrine tissues were concentrated in the splenic lobe of the pancreas. In the grass lizard the endocrine tissue in the splenic lobe of consisted mainly of B, A and D cells and in the ventral lobe the major cell types were PP and D cells. In the desert lizard, on the other hand, the frequency and the pattern of orientation of B, A and D cells were the same in both the splenic and the ventral lobes, but PP cells in the ventral lobe outnumbered those of the splenic lobe. The PP and D cells scattered in the exocrine parenchyma and the long protrusions which they exhibited suggested that these cell exerted paracrine control on the acinar cells. It is speculated that this control by PP cells may be trophic and by D cells inhibitory.     

Insulin, glucagon, pancreatic polypeptide hormone and somatostatin in the goat pancreas: demonstration by immunocytochemistry

Insulin, glucagon, pancreatic polypeptide hormone (PP) and somatostatin immunoreactive cells were demonstrated in the islet of the goat pancreas by the immunofluorescence procedure. Islet cells showing immunostaining for the hormones appeared to have a characteristic distribution. The demonstration of PP and somatostatin within the pancreas of the goat suggests they may be significant in modulating intra- and extra-islet function in this ruminant species.     

Relationship between pancreatic vesicular monoamine transporter 2 (VMAT2) and insulin expression in human pancreas

Vesicular monoamine transporter 2 (VMAT2) is expressed in pancreatic beta cells and has recently been proposed as a target for measurement of beta cell mass in vivo. We questioned, (1) What proportion of beta cells express VMAT2? (2) Is VMAT2 expressed by other pancreatic endocrine or non-endocrine cells? (3) Is the relationship between VMAT2 and insulin expression disturbed in type 1 (T1DM) or type 2 diabetes (T2DM)? Human pancreas (7 non-diabetics, 5 T2DM, 10 T1DM) was immunostained for insulin, VMAT2 and other pancreatic hormones. Most beta cells expressed VMAT2. VMAT2 expression was not changed by the presence of diabetes. In tail of pancreas VMAT2 immunostaining closely correlated with insulin staining. However, VMAT2 was also expressed in some pancreatic polypeptide (PP) cells. Although VMAT2 was not excluded as a target for beta cell mass measurement, expression of VMAT2 in PP cells predicts residual VMAT2 expression in human pancreas even in the absence of beta cells.     

Effect of alloxan on rat pancreatic polypeptide (PP) cells

Summary Injection of alloxan caused an almost total disappearance of insulin cells in the rat pancreas. Planimetric analysis revealed a 50 per cent reduction of the mean islet volume. The number of immunoreactive pancreatic polypeptide (PP) cells per sectioned islet was significantly increased, and the PP cell volume per islet doubled. Assuming an unchanged number of islets, the results indicate an increase in total PP cell mass following alloxan administration.     

Morphological changes in the human endocrine pancreas induced by chronic excess of endogenous glucagon.

The non-tumoral endocrine pancreas from a patient with elevated plasma levels of glucagon due to a malignant glucagonoma was studied immunocytochemically, ultrastructurally and morphometrically. Compared with normal pancreatic islets from control subjects, those of the pancreas from the patient with a glucagonoma showed an almost complete disappearance of A cells, a decrease in immunoreactive insulin in B cells associated with cytological features indicating enhanced synthesis and secretion of this hormone, and an increase in immunoreactive somatostatin and pancreatic polypeptide (PP) accompanied by unusually high numbers of D and PP cells. In addition, numerous B cells were found outside the islets, either forming micro-islets or scattered in the exocrine tissue (nesidioblastosis). The possible mechanisms involved in determining the changes in the secretory activity of B cells and the alterations in the cell composition of the islets are discussed.     

Effects of pancreastatin on insulin and pancreatic polypeptide secretion in the dog

Porcine pancreastatin (1.19 nmol) was administered into the peripheral vein (i.v.) or the third cerebral ventricle (i.t.v.) of dogs and its effect on the secretion of insulin and pancreatic polypeptide (PP) studied. Neither means of administration had any effect on basal and glucose-induced insulin or PP secretion. However, i.v. pancreastatin did inhibit the i.v. CCK-8-induced insulin but not PP release. Pancreastatin may thus play a role in the regulation of insulin secretion in the canine pancreas.     

A light-microscopic immunocytochemical study of the endocrine pancreas in the Australian brush-tailed possum (Trichosurus vulpecula).

The endocrine pancreas of the Australian brush-tailed possum (Trichosurus vulpecula) was investigated by means of immunocytochemistry using the avidin-biotin-peroxidase technique. This was a light microscopic study using this established technique. Serial paraffin sections were stained individually with primary antibodies for glucagon, insulin, somatostatin, and pancreatic polypeptide (PP), showing the same islet. Cells immunoreactive to glucagon, insulin, somatostatin and PP were found in endocrine islets. PP cells appear to be scattered amidst the exocrine portion also. Insulin immunoreactive cells were located in the central region of islet, glucagon in the periphery, somatostatin in periphery and had elongated processes. PP cells were more sparse and located both in the periphery of islet and amidst the exocrine tissue. These results can then be related to a similar study in the same marsupial, but using the immunofluorescence technique and to studies in other marsupials such as grey kangaroo (Macropus fuliginosus) fat-tailed dunnart (Sminthopsis crasicaudata) and the American opossum (Didelphis virginiana). These investigations are part of a study in Australian mammals.     

The effect of diet on the Vervet monkey endocrine pancreas

Vervet monkeys (Cercopithecus aethiops) used for pancreatic endocrine cell distribution studies were found to have been maintained on different diets. Although the effect of dietary changes on the exocrine pancreas has been described in several animals, little, apart from the effect of malnutrition, has been reported for the endocrine pancreas. Reported here are pancreatic endocrine cell distributions in monkeys on a standard diet (n ? 3) compared with monkeys on an atherogenic diet (n = 3). Quantitation of immunolabelled pancreatic endocrine cell types revealed a significant 80% increase in A (glucagon) cell volume in monkeys on an atherogenic diet concomitant with a significant reduction in B (insulin) cell volume to approximately 60% of normal. This reflects a pattern of events that occurs in non-insulin dependent diabetes. An accompanying reduction in PP (pancreatic polypeptide) cell volumes supports our hypothesis that altering A and PP cell volumes could reflect differential gene expression in those cells in the adult in which glucagon and PP are co-localized.     

Embryogenesis of the murine endocrine pancreas; early expression of pancreatic polypeptide gene.

By immunofluorescence on cytospin preparations and on semithin sections of mouse pancreatic buds, we have found glucagon and pancreatic polypeptide (PP)-containing cells at embryonal day 10.5 (E 10.5) in dorsal buds and at E 11.5 in ventral buds. Insulin-containing cells appear in dorsal buds at E 11.5, and one to two days later in ventral buds. Somatostatin-containing cells are detectable from E 13.5 in both dorsal and ventral buds. A quantitative analysis shows that up to E 15.5, PP-containing cells are relatively abundant in both buds. By PCR amplification of oligo(dT)-primed cDNAs prepared from total pancreatic RNA, we also detect PP mRNA from E 10.5 onwards, thus confirming the early expression of the PP gene in the developing mouse pancreas. Analysis of endocrine cells in situ suggests three major patterns of cell distribution in embryonic pancreas. First, individual hormone-containing cells are located within the epithelium of pancreatic ducts. In both dorsal and ventral buds, the majority of these endocrine cells contain PP, but many also contain glucagon, insulin or somatostatin. Secondly, clusters of endocrine cells are found in the pancreatic interstitium. Many of these cells contain both glucagon and PP which, by immunogold labelling of consecutive thin sections, can be shown to co-exist within individual secretory granules. Finally, starting on E 18.5, typical islets are formed with centrally located B cells and with the adult 'one cell-one hormone' phenotype. These results suggest an intriguing ontogenic relationship between A- and PP-cells, and also indicate that PP-containing cells may occupy a hitherto unexpected place in the lineage of endocrine islet cells.     

Immunohistochemical localization of insulin-like growth factor 1 and 2 in the endocrine pancreas of rat,dog, and man,and their coexistence with classical islet hormones

Immunohistochemical techniques were used to study the occurrence and distribution of insulin-like growth factor 1 (IGF-1) and IGF-2 in the pancreas of man, dog, and rat and their possible coexistence with insulin (INS), glucagon (GLUC), somatostatin (SOM) and pancreatic polypeptide (PP). All control experiments, including pre-absorption of the antisera with synthetic peptide hormones, indicated the specificity of the immunoreactions obtained. In all species investigated, IGF-2-immunoreactivity occurred exclusively in INS-immunoreactive cells as was found by the use of consecutive sections and double immunofluorescence on identical sections. In contrast, IGF-1-immunoreactivity co-existed with GLUC-immunoreactivity. In man, singular SOM-immunoreactive cells also contained IGF-1-immunoreactivity. Thus, IGF-1 and IGF-2 can be localized by means of immunohistochemistry in the mammalian pancreas, and can be shown to occur in different islet cell populations. It is presumed that IGF-1 derived from A-cells and/or D-cells acts on the B-cells in a paracrine manner. The co-existence of IGF-2-immunoreactivity and INS-immunoreactivity in the human, rat, and dog endocrine pancreas indicates that mammalian IGF-2 and INS genes are regulated simultaneously.     

Immunocytochemical localisation of the icosapeptide fragment of the PP precursor: a marker for ‘true’ PP cells?

Antisera were raised against the icosapeptide fragment of the pancreatic polypeptide (PP) isolated from the canine pancreas. They were used for the immunocytochemical study of the cellular localisation and distribution of the icosapeptide in the gut and pancreas of various mammals. The results indicate that PP and the icosapeptide coexist in the majority of the PP-immunoreactive cells in the pancreas of cat, dog, pig, monkey and man and in all the PP-immunoreactive cells in the stomach of the cat and dog. The icosapeptide does not seem to occur in cells or nerves containing PP-related peptides, such as peptide YY or neuropeptide Y. PP-immunoreactive cells devoid of the icosapeptide could be demonstrated in the large intestine. These cells are probably distinct from the pancreatic PP cell type, and the PP-immunoreactive material probably represents the homologous peptide YY rather than PP. The present findings support the view that the icosapeptide is part of the PP precursor and hence, only the cells containing immunoreactive icosapeptide in addition to immunoreactive PP are to be considered ‘true’ PP cells. The icosapeptide antisera did not stain PP cells in mouse, rat and guinea-pig, suggesting marked species variation in the amino acid sequence of the icosapeptide portion of the PP precursor.     

Pancreatic polypeptide and glucagon: Non-random distribution in pancreatic islets

When the technique of immunofluorescence is applied to rat pancreas to detect insulin, glucagon, somatostatin and pancreatic polypeptide (PP), two populations of islets having distinct cellular content and topographical distribution can be recognized. Islets from the lower part of the head show a well-defined rim of PP-containing cells, but very few or no glucagon-containing cells. Islets from the body and tail display the familiar rim of glucagon-containing cells and possess very few or no PP-containing cells. This inverse relationship between glucagon and PP-cells in different parts of the pancreas means that caution must be exercised when interpreting functional or morphological observations using different pancreatic fractions.     

扬子鳄胚胎胰腺内分泌细胞发生的免疫组织化学研究

目的 研究13种特异性激素在扬子鳄胚胎胰腺早期发育中的表达。方法 应用免疫组织化学方法。结果 显示生长抑素（SS）,5-羟色胺（5-HT）,胰高血糖素（GLU）,表皮生长因子（EGF）,胰多肽（PP）免疫反应性（IR）细胞出现于第8天,P物质（SP）IR细胞出现于第18天,P53,胃泌素,睾酮,嗜铬素A,血管活性肠肽,上皮膜抗原,胰岛素在各期扬子鳄胚胎胰腺中均未发现。结论 表明SS、5-HT,GLU,EGF、PP和S害扬子鳄胚胎胰腺形成的分化的不同阶段发挥着重要作用。     

Defining the cell lineages of the islets of Langerhans using transgenic mice

In this Special Issue of the Int. J. Dev. Biol., we summarize our own studies on the development of the mouse endocrine pancreas, with special emphasis on the cell lineage relationships between the four islet cell types. Considerable knowledge concerning the ontogeny of the endocrine pancreas has been gained in recent years, mainly through the use of two complementary genetic approaches in mice: gene inactivation and genetic labelling of precursor cells. However, neither gene inactivation in KO mice nor co-localisation of hormones in single cells during development can be taken as evidence for cell lineage relationships among different cell types. The beta-cell lineage analysis was started by selectively ablating specific islet cell types in transgenic mice. We used the diphtheria toxin A subunit coding region under the control of insulin, glucagon or pancreatic polypeptide (PP) promoters, in order to eliminate insulin-, glucagon- or PP-expressing cells, respectively. Contrary to the common view, we demonstrated that glucagon cells are not precursors of insulin-producing cells. These results were in addition the first evidence of a close ontogenetic relationship between insulin and somatostatin cells. We pursued these analyses using a novel, more subtle approach: progenitor cell labelling through the expression of Cre recombinase in doubly transgenic mice. We were able to unequivocally establish that 1) adult glucagon- and insulin-producing cells derive from precursors which have never transcribed insulin or glucagon, respectively; 2) insulin cell progenitors, but not glucagon cell progenitors transcribe the PP gene and 3) adult glucagon cells derive from progenitors which do express pdx1.     

Ontogeny and the effect of aging on pancreatic polypeptide and peptide YY

Pancreatic polypeptide (PP) and peptide YY (PYY) are related neuroendocrine peptides that are expressed in specialized cells. PP is found around the time of birth in different species. PYY in mice and rats has been extensively studied. PYY is the first peptide hormone to appear in both the pancreas and the colon and is initially expressed together with all other pancreatic islet and gut hormones. This suggests that there is a PYY-producing endocrine progenitor cell, at least in rodents. Whether the same is true for other species is unknown. In chickens, however, pancreatic insulin and glucagon cells appear before PYY. After birth, PYY levels in rats and humans reflect adaptation to enteral feeding. Whereas PYY cells increase with age in rodents, no such changes have been found in humans.     

Meal-induced insulin secretion in dogs is mediated by both branches of the autonomic nervous system

We investigated the relationship between autonomic activity to the pancreas and insulin secretion in chronically catheterized dogs when food was shown, during eating, and during the early absorptive period. Pancreatic polypeptide (PP) output, pancreatic norepinephrine spillover (PNESO), and arterial epinephrine (Epi) were measured as indexes for parasympathetic and sympathetic nervous activity to the pancreas and for adrenal medullary activity, respectively. The relation between autonomic activity and insulin secretion was confirmed by autonomic blockade. Showing food to dogs initiated a transient increase in insulin secretion without changing PP output or PNESO. Epi did increase, suggesting beta(2)-adrenergic mediation, which was confirmed by beta-adrenoceptor blockade. Eating initiated a second transient insulin response, which was only totally abolished by combined muscarinic and beta-adrenoceptor blockade. During absorption, insulin increased to a plateau. PP output showed the same pattern, suggesting parasympathetic mediation. PNESO decreased by 50%, suggesting withdrawal of inhibitory sympathetic neural tone. We conclude that 1) the insulin response to showing food is mediated by the beta(2)-adrenergic effect of Epi, 2) the insulin response to eating is mediated both by parasympathetic muscarinic stimulation and by the beta(2)-adrenergic effect of Epi, and 3) the insulin response during early absorption is mediated by parasympathetic activation, with possible contribution of withdrawal of sympathetic neural tone.     

Canine pancreatic polypeptide complementary deoxyribonucleic acid sequence: pancreatic polypeptide and insulin messenger ribonucleic acid distribution in the lobes of the pancreas

The structure of the canine prepropancreatic polypeptide (preproPP) cDNA was determined. The nucleotide sequence conservation between human and canine preproPP is very high for the signal peptide (82%) and the region coding for the 36 amino acid pancreatic polypeptide (PP) (92%). The overall sequence homology for the C-terminal portion of proPP containing the icosapeptide and a C-terminal extension peptide is only 63% whereas the 3'-untranslated regions of human and canine PP mRNA share 73% homology after alignment for maximal homology. The only sequence conservation in icosapeptide is the region coding for the last 10 amino acids of the icosapeptide. Comparison of PP immunoactivity and PP mRNA concentrations in extracts of the developmentally distinct uncinate process and splenic lobes of the canine pancreas revealed the same ratio of mRNA concentrations (16 +/- 6.5) and PP peptide concentrations (18 +/- 7.0) in the uncinate process compared to the splenic lobe (n = 6). However, a similar comparison of insulin C-peptide (CP) immunoactivity and insulin mRNA concentration revealed a smaller ratio of CP immunoactivity (0.37 +/- 0.05) than insulin mRNA (0.58 +/- 0.10) between the same lobes (P less than 0.0074, n = 6). This increased steady state CP concentration relative to insulin mRNA in splenic lobe compared to the uncinate process was not observed for PP peptide and mRNA.     

An immunohistochemical study of the pancreatic endocrine cells of the Korean golden frog, Rana plancyi chosenica

The regional distribution and quantitative frequency of pancreatic endocrine cells were demonstrated in the Korean golden frog (Rana plancyi chosenica Okada), which is known as a Korean endemic species, for the first time, by immunohistochemical methods using specific mammalian antisera to insulin, glucagon, somatostatin and human pancreatic polypeptide (PP). In the pancreas of the Korean golden frog, all four endocrine cell types were demonstrated. Insulin- and glucagon-positive cells were located in the pancreas as single cells or islet-like clusters with frequencies of 85.90±18.28 and 54.30±8.77/1,000/1,000 cells, respectively. Somatostatin-containing cells were also dispersed in the pancreas as single cells or clusters but in the case of clusters, they are exclusively situated in the marginal regions of insulin- or glucagon-positive cell clusters. Cells stained for somatostatin cell frequency was 15.50±3.10/1000 cells. PP-containing cells were also distributed as single cells or clusters with frequency of 53.40±11.96/1,000 cells. Clusters consisted of PP-positive cells are distributed as a core type and a marginally distributed type. Overall, there were 40.84±3.81% insulin-, 26.02±1.71% glucagon-, 7.63±2.09% somatostatin- and 25.51±3.26% PP-IR cells.