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PubMed1997

Activation of the hepatic glycine cleavage enzyme system by glucagon and glucagon-related peptides.

The hepatic glycine cleavage system (GCS) is the principal route for the catabolism of glycine in mammals. Flux through the glycine cleavage system in isolated rat hepatocytes is stimulated about 100% at 100 nM glucagon, with half-maximal stimulation at 4.3 +/- 1.3 nM. Preincubation of the hepatocytes with the glucagon antagonist des-His1-[Glu9]glucagon amide at 10 microM resulted in inhibition of the glucagon-stimulated GCS by approximately 40%, while the antagonist des-His1-[Nle9,Ala11,Ala16]glucagon amide at 10 microM inhibited the glucagon-stimulated GCS by 80%. Oxyntomodulin and glicentin, glucagon-related peptides, were found to stimulate GCS. Oxyntomodulin, 1 microM, and glicentin, 100 nM, stimulated GCS by 100 and 60%, respectively. Glucagon-like peptide 1 (7-36) amide and glucagon (19-29) (10(-10)-10(-7) M) were without effect. Des-His1-[Glu9]glucagon amide at 10 microM inhibited the oxyntomodulin and glicentin-stimulated flux through GCS by about 40%. Thus oxyntomodulin and glicentin can activate the GCS in hepatocytes via interaction with the glucagon receptor but with low affinity.

Animals↗
PubMed1984

Immunocytochemical distribution of endocrine cells in the gastrointestinal tract of the horse.

Endocrine cells immunoreactive for somatostatin, gastrin, glicentin, glucagon, secretin, cholecystokinin, motilin and neurotensin were identified immunocytochemically in the gastrointestinal mucosa of the horse. Somatostatin-, glicentin- and glucagon-immunoreactive cells were very numerous in the cardiac and fundic regions of the stomach, whereas most gastrin-immunoreactive cells were confined to the pyloric region. Somatostatin-immunoreactive cells also were detected in all portions of the small intestine while gastrin-immunoreactive cells were confined exclusively to the upper portion and glicentin-immunoreactive cells were limited to the lower portions of the small intestine. Secretin-, cholecystokinin- and motilin-immunoreactive cells were observed only in the duodenum, while neurotensin-immunoreactive cells were confined primarily to the ileum. In the large intestine, somatostatin- and glicentin-immunoreactive cells were detected in the colon and rectum. The preferential location of endocrine cells provides additional information for future studies on the physiological roles of gastrointestinal peptides in the gastrointestinal tract of the horse.

Animals↗
PubMed1985

Localization of glucagon-like peptide (GLP) immunoreactants in human gut and pancreas using light and electron microscopic immunocytochemistry.

The distribution of peptide immunoreactivities predicted from the sequence of the human preproglucagon gene in enteroglucagon (EG; glicentin-like immunoreactant-containing) cells of the human gut and A cells of the pancreas has been determined by light and electron microscopic immunocytochemistry. At light microscopy the application of peroxidase-antiperoxidase and immunogold-silver staining methods has revealed that glucagon-like peptide (GLP-1 and GLP-2) immunoreactivities coexist with a glicentin-related immunodeterminant in human colorectal EG cells and pancreatic A cells. Using single and double colloidal gold probe electron immunocytochemistry, we have been able to show the coexistence of glicentin, GLP-1, and GLP-2 immunoreactivities within single EG cell secretory granules. No morphologic segregation of the proglucagon immunoreactants was observed in EG cells of the colonic mucosa. In pancreatic A cells we have localized GLP-1, GLP-2, and glucagon-[16-29] immunoreactivities solely to the electron-dense core of the secretory granules, whereas glicentin-related immunoreactivity was restricted to the electron-lucent halo. The results obtained in the present study have shown that the peptide immunoreactivities predicted from cDNA sequencing of the human preproglucagon gene are indeed expressed in colorectal EG and pancreatic A cells. The topographical segregation of immunoreactivities in the A cell secretory granule shows that antigenic determinants derived from the C-terminal portion of proglucagon are stored with glucagon in the core of the secretory granule.

Colon↗
PubMed1987

Distribution of oxyntomodulin and glucagon in the gastrointestinal tract and the plasma of the rat.

Oxyntomodulin (OXM), an intestinal glucagon-containing peptide extended at its C-terminal end by an octa-peptide, is one of the gut glucagon-like immunoreactants (GLI) or enteroglucagon. The distribution of OXM and glucagon was determined in the gastrointestinal tract and in the plasma of the rat. Reversed-phase HPLC, associated with RRA or RIA, performed with an N-terminally directed glucagon antiserum (GOL), was used. HPLC of intestinal extracts or plasma separated the GOL immunoreactivity into three peaks: two major peaks coeluting with a preparation of rat glicentin (peak I, partially purified from rat intestine) and porcine or rat OXM, respectively, and a smaller peak coeluting with glucagon. The behavior of the three peaks in the analytical systems matched that of glicentin, OXM, and glucagon, respectively, allowing their identification. The concentrations of OXM picomoles per g of tissue) gradually increased from the duodenum (9 +/- 1) to ileum (93 +/- 4), thereafter decreasing in cecum and colon (22 +/- 3). In the gut, OXM, glucagon, and peak I averaged 40%, 1%, and 59% of the total GLI, respectively. OXM was present in significant amounts in the pancreas (18% of GLI) and stomach (27% of GLI), two tissues in which it accounted, together with glucagon, for almost the totality of GLI. In 24 h-fasted rats, plasma concentrations of OXM, glucagon, and peak I, determined after HPLC with GOL antiserum, were 15.1 pM, 8.6 pM, and 12.3 pM, respectively. Two hours after refeeding, both OXM and peak I were significantly increased (P less than 0.05 and P less than 0.02) by a similar factor (2-fold), while glucagon remained unchanged. When the HPLC results were compared with RIA measurement of GLI (GOL antiserum) and glucagon (with a C-terminal glucagon antiserum) in plasma, enteroglucagon (GOL--C-terminal glucagon antiserum immunoreactivities) correlated well with the sum of OXM plus peak I. The combination of HPLC and RRA or RIA allows the unambiguous determination of OXM, glucagon, and glicentin (peak I) in tissues and plasma. In the rat intestine and in the plasma, OXM and glicentin appear roughly in the same ratio and seem to be the major components, if not the totality, of enteroglucagon.

Animals↗
PubMed1983

Endocrine cells in human intestine: an immunocytochemical study.

The regional and topographic distribution of endocrine cells in the human intestine was examined by immunohistochemistry. The frequency of endocrine cells was greatest in the small intestine with the rectum next in order. The duodenum and jejunum harbored a large number of different endocrine cell types; the spectrum of cell types gradually narrowed distally in the intestine. 5-Hydroxytryptamine-containing enterochromaffin cells were present in all regions of the intestine and comprised the single largest endocrine cell population. In addition, a minor proportion of these cells contained substance P. The second largest cell population consisted of the glicentin cells, which were notably numerous in the ileum and colon. The somatostatin cells also occurred throughout the digestive tract. Cells storing cholecystokinin, motilin, secretin, or gastric inhibitory polypeptide were more numerous in the proximal and middle small intestine than distally. Gastrin cells were few and occurred in the proximal duodenum only. Other cells in the small intestine reacted with antiserum directed against the common C-terminus of gastrin and cholecystokinin. The number of these cells greatly exceeded the sum of cells reactive to gastrin-specific or cholecystokinin-specific antisera. Cells displaying beta-endorphin, pro-gamma-melanocyte-stimulating hormone, or beta-lipotropin immunoreactivity, or a combination of these, were found in the small intestine. Cells storing neurotensin, glicentin, substance P, or pro-gamma-melanocyte-stimulating hormone increased in number distally in the small intestine. Enterochromaffin cells, glicentin cells, and somatostatin cells were the predominant endocrine cell types in the colon and rectum. The majority of the glicentin-immunoreactive cells also contained glucagon and pancreatic polypeptide-like immunoreactivity. Endocrine cells in the large intestine often possessed basal processes.

Adult↗
PubMed1984

Glucagon-related peptides in the human gastrointestinal mucosa.

We studied the chromatographic profile and the distribution of glucagon-related peptides in the human gastrointestinal mucosa, using radioimmunoassays directed against the glucagon 6-15 and 19-29 sequences, and against the glicentin sequences 15-30 and 61-69, and a radioreceptor assay for glucagon. Very small amounts of glucagon-related peptides were found in the gastric mucosa, whereas at least four different components could be identified in the distal intestine. One component (mean concentration 130 pmol/g ileal mucosa) is similar to porcine glicentin for size and C-terminal extension, but differs from the glucagon part of the molecule in the N-terminal extension. A second component (mean concentration 131 pmol/g) is probably identical to porcine peak II enteroglucagon (glicentin 33-69), and a third component (7.9 pmol/g) seems to be identical with glucagon. A fourth component containing the glucagon sequence plus an N-terminal extension was also identified (1.7 pmol/g). Thus the human intestinal mucosa contains large amounts of peptides containing the glucagon sequence; at least one of these probably also possesses glucagon-like bioactivity. The proposed structures of the four components are consistent with the base sequence of the first half of the human glucagon gene.

Gastric Mucosa↗
PubMed1983

Gut endocrine cells in rat intestinal-tract carcinoma induced by 1,2-dimethylhydrazine.

Gut endocrine cells in a total of 122 intestinal-tract adenocarcinomas induced in inbred Wistar rats by 1,2-dimethylhydrazine dihydrochloride were examined histologically, ultrastructurally, and immunohistochemically for gastrin, somatostatin, vasoactive-intestinal polypeptide (VIP), and glicentin (enteroglucagon). Of the 122 tumors, argyrophil cells were detected in 42 tumors (34.3%) comprising 15 tumors of the well differentiated type and 27 tumors of the poorly differentiated type, including signet-ring-cell carcinomas. Of the 27 tumors of the poorly differentiated type, 12 were regarded as endocrine-cell carcinomas composed of numerous argyrophil or argentaffin cells and mucus-containing cells. Immunohistochemically, 7 of the 12 tumors had glicentin and two of these seven tumors also had gastrin and argentaffin cells synchronously. None of the tumors showed immunoreactivity for somatostatin and VIP. Nine of the 12 tumors metastasized to the lung, pancreas, liver, mesenterium, omentum, and lymph nodes. The metastatic foci of these tumors were also shown to have glicentin and argentaffin cells. Ultrastructurally, four types of endocrine granule were found in the tumor cells and amphicrine cells containing endocrine granules and mucous granules were noted. These endocrine-cell tumors were assumed to develop from totipotent immature cells of endodermal origin.

1,2-Dimethylhydrazine↗
PubMed1985

Solitary gastric polyps in the fundic gland area. A histochemical study.

Six solitary gastric polyps in the acid-secreting fundic mucosa were histochemically investigated using the mucin histochemistry, immunoperoxidase method, and silver methods for endocrine cells. Histologically, the polyps were grouped into three types: they largely consisted of either hyperplastic foveolar cells (group 1), normal-appearing fundic gland cells with mild cystic changes (group 2) or hyperplastic fundic gland cells with cystic dilatation (group 3). The presence of parietal cells and mucous neck cells was confirmed in all polyps by the immunoperoxidase method using parietal cell autoantibody and the paradoxical Concanavalin A staining, respectively. Regarding the endocrine component, somatostatin-containing cells, Grimelius-positive argyrophil cells, and Fontana-Masson-positive enterochromaffin cells were scattered in the fundic gland area of the polyps as well as in the surrounding normal-appearing fundic mucosa. Gastrin-containing cells were absent. In one of the group 2 polyps and both group 3 polyps, a varying number of glicentin-containing cells were found among the fundic gland components: In one polyp in group 3, glucagon immunoreactivity was detected in the glicentin-containing cells. These findings suggest that some of the polyps express characteristics of the fetal fundic mucosa, since glicentin and glucagon immunoreactivities in normal human stomach have been detected exclusively in the fetal fundus.

Gastric Fundus↗
PubMed2004

Significance of prohormone convertase 2, PC2, mediated initial cleavage at the proglucagon interdomain site, Lys70-Arg71, to generate glucagon.

To define the biological significance of the initial cleavage at the proglucagon (PG) interdomain site, K70-R71 downward arrow, we created two interdomain mutants, K70Q-R71Q and R71A. Cotransfection studies in GH4C1 cells show significant amounts of glucagon production by PC2 along with some glicentin, glicentin-related polypeptide-glucagon (GRPP-glucagon) and oxyntomodulin from wild-type PG. In contrast, a larger peptide, PG 33-158, and low amounts of GRPP-glucagon are predominantly generated from interdomain mutants. HPLC analysis shows a 5-fold increase in glucagon production by PC2 from wild-type PG and a corresponding 4-fold lower accumulation and secretion of unprocessed precursor relative to interdomain mutants. PC2 generates significant levels of glucagon from a glicentin (PG 1-69) expression plasmid, whereas PC1/3 produces only modest amounts of oxyntomodulin. Employing a major PG fragment (PG 72-158) expression plasmid, we show that PC1/3 predominantly generates glucagon-like peptide (GLP)-1, whereas PC2 produces only N-terminally extended GLP-1. Surprisingly, production of GLP-1 and GLP-2 by PC1/3 from interdomain mutants, compared with wild-type PG, is not significantly impaired. In addition to PC2 and PC1/3, PC5/6A and furin are also able to cleave the sites, K70-R71 downward arrow and R107-X-R-R110 downward arrow in PG. We show a much greater ability of furin to cleave the monobasic site, R77 downward arrow, than at the dibasic site, R124-R125 downward arrow, which is also weakly processed by PC5/6A, indicating overlapping specificities of these two convertases mainly with PC1/3. We propose here a trimer-like model of the spatial organization of the hormonal sequences within the PG molecule in which the accessibility to prohormone convertase action of most cleavage sites is restricted with the exception of the interdomain site, K70-R71, which is maximally accessible.

Animals↗
PubMed1979

A study of glucagonomas by light and electron microscopy and immunofluorescence.

Five tumors associated with the complete glucagonoma syndrome, as well as a series of glucagon-cell adenomas from three patients without this syndrome, were investigated by light and electron microscopy and by immunofluorescence. All tumors associated with the syndrome were large, from 3 to 35 cm along the major axis, and three of them were proved to be malignant. No common histologic arrangement of tumor cells was apparent for the five neoplasms examined. Immunofluorescent staining for glucagon and glicentin was carried out: while most cells were negative, a varying number of scattered cells were positive with both antisera in all tumors except one; three tumors contained more glicentin- than glucagon-immunoreactive cells. Moreover, three tumors were multihormonal, witn cells positive for pancreatic polypeptide and/or insulin. Ultrastructurally, the secretory granules of cells from these tumors were not typical of those found in A-cells from adult human islets. The glucagon-cell tumors from patients without the syndrome were benign, usually multiple, and were small, with diameters from 0.5 mm to 1 cm. In most cases, the cells from these neoplasms arranged in a characteristic pattern (ribbonlike or "gyriform"). In most tumors, the majority of cells showed both glucagon and glicentin immunofluorescence and the ultrastructural appearance of their secretory granules was similar to that of normal islet A-cells. From the morphologic point of view, therefore, cells from tumors not associated with the glucagonoma syndrome resemble normal glucagon cells more closely than those from tumors associated with the syndrome.

Adult↗
PubMed1985

Histologic and immunocytochemical study of endocrine cells in the gastrointestinal tract of the cow and calf.

The regional distribution and relative frequency of argyrophil cells, and of cells immunoreactive for 5-hydroxytryptamine (5-HT), substance P (SP), somatostatin, glicentin, glucagon, bovine pancreatic polypeptide (BPP), gastrin, leucine-enkephalin, gastric inhibitory polypeptide (GIP), cholecystokinin, secretin, motilin, and neurotensin were studied in 9 segments from the gastrointestinal tract of cows (greater than 1 year old) and calves (less than 3 months old). Argyrophil cells, 5-HT-immunoreactive cells, and somatostatin-immunoreactive cells were distributed throughout the gastrointestinal tract, whereas the other immunoreactive cells were more restricted in distribution. Most endocrine cells were more numerous in the calf than in the cow. This feature was most conspicuous in the abomasum. In the abomasum, argyrophil cells in the cow and calf and 5-HT-immunoreactive cells in the calf were found predominantly in the fundic region, whereas somatostatin-immunoreactive cells and gastrin-immunoreactive cells in the cow and calf and 5-HT-immunoreactive cells in the cow were most numerous in the pyloric region. Substance P-, glucagon-, BPP-, and leucine-enkephalin-immunoreactive cells were rarely detected. In the small intestine, argyrophil cells, 5-HT-, SP-, somatostatin-, gastrin-, GIP-, cholecystokinin-, secretin-, and motilin-immunoreactive cells were most numerous in the duodenum. Neurotensin-, glicentin-, glucagon-, and BPP-immunoreactive cells were detected with the highest frequency in the ileum. In the large intestine, argyrophil cells and 5-HT-, glicentin-, BPP-, somatostatin-, glucagon-, and SP-immunoreactive cells occurred with the highest frequency in the rectum.

Abomasum↗
PubMed1998

Glucagon- and NPY-related peptide-immunoreactive cells in the gut of sea bass (Dicentrarchus labrax L.): a light and electron microscopic study.

Glucagon and peptide of the neuropeptide Y (NPY) family immunoreactivities were studied in the gut of sea bass (Dicentrarchus labrax) using antisera against bovine/porcine glucagon, porcine glucagon, glicentin (10-30), bovine pancreatic polypeptide (PP), peptide tyrosine tyrosine (PYY), salmon PYY (sPYY), and NPY. Glucagon-, glicentin-, PYY-, and NPY-immunoreactive (ir) cells were detected in the stomach, and glucagon-, PP-, PYY-, sPYY-, and NPY-ir cells in the intestine. PP, PYY, and NPY immunoreactivities coexisted in intestinal endocrine cells (NPY-like peptide containing cells), in some of which there was also glucagon immunoreactivity. Preabsorption tests indicated that different products of the glucagon gene(s) are probably expressed in the stomach and intestine of sea bass and that the peptides belonging to the NPY family in the endocrine cells of the intestine are more similar to NPY than to other peptides of this family. Glucagon-ir cells in the stomach, and glucagon/NPY-like containing cells in the intestine, were characterized by conventional and immunogold electron-microscopic techniques. The glucagon cells had secretory granules with a clotted content, the gold particles being observed in both the core and the halo. Glucagon/NPY-like cells showed two types of secretory granules differing in size, both of which were immunogold labeled with anti-NPY and anti-sPYY; the smaller granules were weakly immunogold labeled with anti-glucagon.

Animals↗
PubMed1997

Enteroglucagon.

The gene encoding proglucagon, the biosynthetic precursor of glucagon, is expressed not only in the pancreatic islets but also in endocrine cells of the gastrointestinal mucosa. The proglucagon (PG)-derived peptides from the gut include glicentin (corresponding to PG 1-69); smaller amounts of oxyntomodulin (PG 33-69) and glicentin-related pancreatic polypeptide (GRPP, PG 1-30); glucagon-like peptide-1 (GLP-1, PG 78-107 amide); intervening peptide-2 (IP-2, PG 111-122 amide); and glucagon-like peptide-2 (GLP-2, PG 126-158). All are secreted into the blood in response to ingestion of carbohydrates and lipids. Only oxyntomodulin and GLP-1 have proven biological activity; oxyntomodulin possibly because it interacts (but with lower potency) with GLP-1 and glucagon receptors. GLP-1 is the most potent insulinotropic hormone known and functions as an incretin hormone. It also inhibits glucagon secretion and, therefore, lowers blood glucose. This effect is preserved in patients with non-insulin-dependent diabetes mellitus, in whom infusions of GLP-1 may completely normalize blood glucose. However, GLP-1 also potently inhibits gastrointestinal secretion and motility, and its physiological functions include mediation of the "ileal-brake" effect, i.e. the inhibition of upper gastrointestinal functions elicited by the presence of unabsorbed nutrients in the ileum. As such it may serve to regulate food intake.

Animals↗
PubMed1997

Intestinal growth is associated with elevated levels of glucagon-like peptide 2 in diabetic rats.

Glucagon-like peptide 2 (GLP-2) has recently been identified as a novel intestinal growth factor. Because experimental diabetes is associated with bowel growth, we examined the relationship between GLP-2 and intestinal growth in rats made diabetic by streptozotocin (STZ) injection and treated with or without insulin for 3 wk. Ileal concentrations of the intestinal proglucagon-derived peptides, i.e., glicentin + oxyntomodulin, and GLPs 1 and 2, were increased by 57 +/- 20% above those of controls in untreated STZ diabetes (P < 0.05-0.001). Similar increases in plasma concentrations of glicentin + oxyntomodulin (77 +/- 15% above controls, P < 0.01) and GLP-2 (91 +/- 32% above controls, P < 0.05) were seen in untreated STZ diabetes. Both wet and dry small intestinal weight increased by 74 +/- 20% above controls (P < 0.01) in STZ diabetes, and macromolecular analysis indicated parallel increases in both protein (P < 0.001) and lipid (P < 0.05) content. Villus height (P < 0.001) and crypt depth (P < 0.01) were also increased in untreated diabetic rat intestine. Insulin therapy prevented the changes in plasma GLP-2 and intestinal mass seen in untreated STZ diabetes. Thus STZ diabetes is associated with both increased production of GLP-2 and enhanced bowel weight, thereby suggesting a role for GLP-2 in diabetes-associated bowel growth.

Animals↗
PubMed1989

High-affinity GABA uptake in a subpopulation of somatostatin cells in rat pancreas.

The aim of this study was to localize the high-affinity uptake of [3H]-GABA in Langerhans islets of rats aged 2.5, 7.5, and 75 days. On high-resolution autoradiography, cells presenting characteristic somatostatin granules were labeled, whereas others containing similar granules appeared nearly devoid of silver grains. Immunogold detection with antisomatostatin antibodies and high-resolution autoradiography suggested that uptake of GABA is indeed performed by somatostatin cells. To test the heterogeneity of uptake frequency in somatostatin cells, a second approach, coupling immunohistochemistry with anti-somatostatin, anti-PP, anti-glucagon, anti-glicentin, and anti-CCK antibodies, and low-resolution autoradiography, was applied on paraffin sections. It demonstrated that the uptake ability is not characteristic of all the somatostatin cells but of only a subpopulation of them. A few cells not immunoreactive to the anti-somatostatin antiserum also appeared to be able to take up GABA. Moreover, except for a rare few, the PP-glucagon-, glicentin-, and CCK-39-immunoreactive cells were not labeled by autoradiography.

Animals↗
PubMed1983

Immunocytochemical localization of glucagonlike and gastric inhibitory polypeptidelike peptides in the pancreatic islets and gastrointestinal tract.

The distribution of cells displaying glucagonlike or gastric inhibitory polypeptide (GIP)-like immunoreactivity was examined in the pancreatic islets and gastrointestinal tracts of rats, dogs, and humans. A-cells in the pancreatic islets in all three species were stained by antisera having regional specificity for pancreatic-type glucagon, gut-type glucagon (glicentin), or GIP. Oxyntic A-cells of the gastric mucosa in dogs and humans also were stained comparably by these three antisera. In contrast, the K- and L-cells in the intestinal mucosa of those species were stained only by antisera capable of reacting with GIP or gut-type glucagon, respectively. Tests of antibody specificity showed that the GIP antiserum did not cross-react with either pancreatic- or gut-type glucagon. Likewise, the glucagon antisera showed no cross-reactivity with GIP. Hence, these findings suggest that pancreatic and gastric A-cells contain a peptide with GIP-like immunoreactivity distinct from glucagon or glicentin per se. Although the exact basis of th GIP-like immunostaining of A-cells is unknown, it may be due to the presence of a glucagon precursor sharing certain amino-acid sequences with GIP. This hypothesis is consistent with several recent investigations showing that the processing of proglucagon molecules differs between the A- and L-cells.

Animals↗
PubMed1984

Endocrine cells in extrahepatic bile duct carcinoma.

A total of 44 extrahepatic bile duct carcinomas comprising 13 well-differentiated adenocarcinomas, 25 moderately differentiated adenocarcinomas, and 6 poorly differentiated adenocarcinomas were examined histologically and immunohistochemically for somatostatin, gastrin, and glicentin. Argyrophil cells, argentaffin cells, and somatostatin- and gastrin-immunoreactive cells within the tumor were detected in 46.2%, 15.4%, 23.1%, and 15.4% of well-differentiated adenocarcinomas, and in 16.0%, 8.0%, 12.0%, and 4.0% of moderately differentiated adenocarcinomas, respectively. No tumor tissues of poorly differentiated adenocarcinomas contained endocrine cells. A statistically significant difference in the frequency of argyrophil cells was observed between well and poorly differentiated adenocarcinoma. The incidence of argyrophil cells and somatostatin-immunoreactive cells in nonneoplastic mucosa adjacent to well-differentiated adenocarcinoma was higher than in that adjacent to poorly differentiated adenocarcinoma. Glicentin-immunoreactive cells could not be demonstrated either in tumor tissue or in nonneoplastic mucosa of the extrahepatic bile duct. With reference to the histogenesis of extrahepatic bile duct carcinoma, it was assumed from these results that the development of well-differentiated adenocarcinoma might be closely related to the occurrence of endocrine cells and that poorly differentiated adenocarcinoma might develop from ordinary mucosa.

Adenocarcinoma↗
PubMed1986

Gut endocrine cells in rat stomach carcinoma induced by N-methyl-N'-nitro-N-nitrosoguanidine.

Gut endocrine cells in a total of 18 gastric adenocarcinomas in inbred Wistar rats induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and gastrin or serotonin, were examined histologically, ultrastructurally, and immunohistochemically for gastrin, somatostatin, calcitonin, glicentin, and serotonin. A large number of argyrophil cells were observed in 17 tumors (94.4%) and 14 tumors (77.8%) had argentaffin cells. Immunohistochemically, C-terminal fragment of gastrin (G17) immunoreactivity was observed in 15 (82.2%) out of the 18 tumors, but 3 G17-positive tumors had no G 34 immunoreactive cells in rats treated with MNNG plus gastrin. Serotonin immunoreactivity was detected in 14 tumors (77.8%). Somatostatin immunoreactivity was detected in 7 of the 11 tumors (63.6%) in rats treated with MNNG plus gastrin whereas no tumor in rats treated with MNNG plus serotonin had somatostatin, the difference of the incidence being significant (P less than 0.05). One endocrine cell carcinoma which consisted mainly of serotonin-producing cells was observed in a rat treated with MNNG plus serotonin. Calcitonin and glicentin immunoreactivity was not demonstrated in any tumors. Ultrastructurally, three types of endocrine granule were found in the tumor cells. These data suggest that hormonal environment in stomach carcinogenesis may influence the expression of endocrine cells within the tumors.

Adenocarcinoma↗