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Ultrastructural investigation and quantitative analysis of endocrine cells of intestine were studied at the period from 15 minutes to 24 hours after inoculation using the model of experimental esherichiosis. The results obtained allow to determine the succession of changes of different types of endocrine cells in dependence on localization and duration of influence.
The decrease in active kidney parenchyma amount causes disorders in hormone secretion processes and their inactivation failure. Experimental thyroparathyroidectomy is connected with an abrupt reduction in endocrine cells and hormones produced by them, which can be a stimulating factor as far as the increase and intensity of endocrine gastric cells activity is concerned. The aim of the study was the histomorphological and immunohistochemical evaluation of these cells in the gastric pylorus. Thyroparathyroidectomy was performed in rats 30 days after nephrectomy. Fragments of gastric pylorus were collected 14 days after the operation. Paraffin sections were stained with H+E and silver method. Immunohistochemical reactions were conducted using antibodies against calcitonin gene-related peptide (CGRP), somatostatin (ST), synaptophysin (SPh), neuron-specific enolase (NSE), and chromogranin (CgA). The results showed an increase in number of endocrine cells in stomachs of rats in experimental group as compared to controls. Endocrine cells were larger and contained more secretory granules.
Using histological and immunhistochemical techniques, nine endocrine cell types were observed in the mucosa of the gastrointestinal tract of the toad, Bufo regularis, viz. enterochromaffin, somatostatin, glucagon, pancreatic polypeptide (PP), secretin, gastric inhibitory peptide (GIP), gastrin-C-terminal pentapeptide (GTPP), neurotensin and bombesin cells. The enterochromaffin cells were distributed throughout the gastrointestinal tract except the rectum. Somatostatin, glucagon, PP, secretin, GIP and GTPP cells were observed both in the stomach and in the small intestine. Neurotensin cells were seen only in the ileum and bombesin cells only in the pyloric and antral parts of the stomach. Immunostaining of consecutive sections did not reveal more than one polypeptide hormone in any of these cell types. It is concluded from the present results that the toad gastrointestinal mucosa contains endocrine cell types that are more or less homologous to those in the mammal alimentary tract, though some of them exhibit a different topographic distribution.
By means of the light and electron microscopy methods structural bases of differentiation and contents of endocrine cells of the stomach epithelium have been studied during the white rat pre- and postnatal development. The development of the endocrine epithelial cells occurs in parallel with the exocrinic ones. Endocrine EC-, G-, D-, P-cells are the first to be revealed in composition of the embryonal stomach epithelium, the others--during the early postembryonic period. The differentiation of the endocrine cells is characterized with asynchronism, is accompanied with a gradual development of organells, increasing amount of secretory granules and appearance of polarity in their distribution. By the 30th day of the postnatal development, the amount of the endocrine cells in the stomach epithelium increases by 5 times in comparison to those in the 1-day-old animals, with simultaneous reaching of the high level in specific differentiation.
The immunofluorescent cell content of the pancreas of 8--40-wk fetuses and of 1.5--5-mo Caucasian infants was quantitatively evaluated using anti-insulin, anti-glicentin, anti-glucagon, anti-somatostatin, and anti-pancreatic polypeptide antisera. The most significant findings are: (1) the pancreas of 8--10 wk fetuses contains a sizable population of endocrine cells reacting exclusively to anti-glicentin antiserum. This cell population decreases and disappears in later stages and is replaced by the adult type glucagon/glicentin immunoreactive cell; (2) the pancreatic polypeptide-rich region shows a lower relative endocrine cell content as compared with the glucagon-rich region and its islets appear smaller; (3) in the total pancreas, the relative (volume density) and absolute (microliter) insulin cell content increases regularly with age, while the relative volume of glucagon cells peaks in fetal life (wk 17--20) to decrease in infants, although remaining at higher levels than in adults; the relative and absolute volumes of somatostatin cells are elevated in fetal and infant stages studied where they represent the second most abundant cell type, while pancreatic polypeptide cells appear to least abundant cells during prenatal and infant life. These data show several differences with the pattern of the respective endocrine cell populations in the adult pancreas.
A 33-year-old woman who presented with vaginal bleeding was diagnosed to have neuroendocrine small cell carcinoma based on cervical smear and biopsy. Hysterectomy was performed, and a tumor measuring 5.5 X 2 mm was found at the squamocolumnar junction of the uterine cervix. In the immediate vicinity of the tumor, there was proliferation of cytologically benign endocrine cells in the normal endocervical glands and in the glands showing intraepithelial glandular neoplasia. Both the hyperplastic endocrine cells and the invasive tumor cells showed argyrophilia and immunostaining for neuron-specific enolase, neurofilament, and chromogranin. The topographical relationship suggests that endocrine cell hyperplasia may represent a precursor of neuroendocrine carcinoma of the cervix.
We made a mutated progastrin cDNA construct that contains a cleavage site (-Arg(-4)-Arg(-3)-Lys(-2)-Arg-1) specific for the Kex2-like endoprotease furin, located ahead of the bioactive gastrin. For expressing the mutated progastrin cDNA, we used two non-endocrine cell lines, CHO and COS-7. CHO cells exhibit amidating enzyme activity and levels of amidation enzyme mRNA as high as those in the pituitary-derived endocrine cell line GH3, whereas COS-7 cells have far less amidating activity and lower amounts of mRNA. Mutant progastrin-expressing CHO cells produced mostly amidated gastrin. Gel filtration showed the size of this gastrin corresponded to that of the synthetic human gastrin-17. In contrast, COS-7 cells produced glycine-extended gastrin and only a small amount of amidated gastrin. The difference in the amount of amidated gastrin products produced by the two non-endocrine cell lines is due to differing amounts of the amidation enzyme contained in each cell line.
Serine proteases play essential roles in a wide variety of cellular processes in endocrine cells. There is a growing interest in the roles of serine protease inhibitors, or serpins, as key regulators of their activity. We have cloned two neuroserpin cDNAs from a rat pituitary cDNA library and confirmed tissue plasminogen activator as a potential target for this inhibitor. We show that neuroserpin transcripts are expressed by endocrine cells in the adrenal and pituitary glands and that immunoreactive neuroserpin is stored in densely cored secretory granules in these cells. Overexpression of neuroserpin in an anterior pituitary corticotroph cell line results in the extension of neurite-like processes, suggesting that neuroserpin may play a role in cell communication, cell adhesion, and/or cell migration.
CD57, a glycoprotein, is a specific antigen presented on the surface of human natural killer cells and killer cells. The monoclonal antibody to CD57 has been available. In this study, the avidin-biotin-peroxidase complex (ABC) technique visualized with glucose oxidase-DAB-nickle (GDN) was used to detect the expression of CD57 in endocrine cells of human pancreas. The results showed that the CD57 immunoreactive (CD57-IR) cells were scattered throughout human pancreas. Most of positive cells were localized in the pancreatic islets. Grouped or single cells occurred intercalated between acinar cells, as well as in the epithelium of pancreatic ducts. The anti-CD57-monoclonal antibody stained the myelin sheaths of nerve fibers in all tissues investigated. Alternative sections immunostained with antibodies against bioactive peptides proved the coexistence of CD57 and Glu, SS, HPP or PS in endocrine cells. The significance of the expression of CD57 immunoreactivity in endocrine cells of human pancreas was discussed.
INTRODUCTION: We recently established a method of isolation and primary monolayer culture of porcine pancreatic endocrine cells that involves the use of nicotinamide. AIM: To obtain genetic information on cultured porcine endocrine cells and to examine cell function in relation to insulin secretion during long-term culture. METHODOLOGY: Gene expression of insulin and several transcription factors, including PDX-1, Beta2/NeuroD, Pax6, and Nkx6.1, was assessed by reverse transcription-polymerase chain reaction analysis, and the insulin protein level was estimated by immunohistochemistry and enzyme assay during a 12-week period. RESULTS: During the culture period, insulin accumulation in the medium at 5 weeks had decreased by almost half the level of accumulation in the first week. In contrast to the alteration of secretory function, insulin gene expression was maintained for at least 12 weeks, and regulatory transcription factors were expressed at the same levels until 9 weeks. These observations suggest that gene expression is not involved in the cause of decreased baseline insulin secretion. Moreover, although the insulin response to high glucose and potassium loading was maintained, the magnitude of the responses to both stimuli was attenuated in the late period of culture. Insulin secretion tended to decrease in our culture system, and the secretory response to pharmacological stimulation was attenuated despite maintenance of messenger RNA expression of insulin and other islet-specific genes for at least 9 weeks in vitro. CONCLUSION: These findings indicate that cell integrity is maintained and that the alteration in insulin secretion must be explained by another mechanism.
There is evidence for a pathway involving small intestinal CCK-producing entero-endocrine cells and visceral afferent nerve fibers in signaling the effect of luminal nutrients on gastrointestinal and food intake regulation. In order to investigate the type of anatomical apposition that exists between CCK cells and vagal afferents, CCK immunocytochemistry was performed on tissue from rats whose vagal afferent fibers to the abdomen had previously been labeled in vivo by injecting the fluorescent carbocyanine dye DiI into the nodose ganglia. CCK immunoreactive (CCK-IR) cells were more abundant than vagal afferent fibers, but both were present throughout the small intestine as well as in crypts and villi. Few CCK-IR cells were in close (< 5 microns) anatomical contact with vagal afferent axons, and the latter did not produce suspicious terminal specializations near CCK-IR cells. Most labeled vagal afferent axons, which distributed strictly within the crypt and villous lamina propria, were at distances of tens to hundreds of microns to the nearest CCK-IR cell. These findings strongly support the idea that CCK released from entero-endocrine cells acts on vagal sensory fibers in a paracrine fashion, but do not rule out the presence of a few very close, neurocrine-like contacts or a humoral mode of action. Possible implications of such an arrangement on CCK-mediated satiety are discussed.
The profile of hormone secretion from the gastrointestinal tract on food ingestion depends to a great extent on the composition of the meal. High levels of protein result in a quantitatively and qualitatively different response compared with a meal rich in fats. The outstanding question is whether this differential response is driven by the ability of gastroenteric endocrine cells to directly sense the contents of the lumen via apical microvilli. Alternative effectors would include activation of the intrinsic and extrinsic innervation or other epithelial cell populations. The data available indicate that the role of the gastrointestinal innervation is relatively limited and is probably a major factor only in the postprandial responses of hormones released from endocrine cells in the distal small intestine. However, whether nutrients directly stimulate gastroenteric endocrine cells or another epithelial cell type has yet to be established.
The regional distribution and frequency of pancreatic endocrine cells in ddY mice were studied by an immunohistochemical (peroxidase anti-peroxidase; PAP) method using four types of specific antisera against insulin, glucagon, somatostatin and human pancreatic polypeptide (hPP). In the pancreatic islets, most of insulin-immunoreactive (IR) cells were located in the central portion. Most of glucagon- and somatostatin-IR cells were observed in peripheral regions although a somewhat smaller number of cells were also located in the central regions. HPP-IR cells were randomly distributed throughout the entire islets. In the exocrine pancreas, insulin-, glucagon-, somatostatin- and hPP-IR cells were detected; they occurred mainly among the exocrine parenchyma as solitary cells. Cell clusters consisted of only insulin- or only glucagon-IR cells and were distributed in the pancreas parenchyma as small islets. In addition, insulin- and glucagon-IR cells were also demonstrated in the pancreatic duct regions. Insulin-IR cells were located in the epithelium and sub-epithelial connective tissue regions as solitary cells and/or clusters (3-4 cells), and glucagon-IR cells were mainly located in the epithelium as solitary cells. Overall, there were 63.89+/-5.39% insulin-, 26.52+/-3.55% glucagon-, 7.25+/-2.83% somatostatin- and 1.90+/-0.58% hPP-IR cells. In conclusion, some strain-dependent characteristic distributional patterns of pancreatic endocrine cells were found in the ddY mouse.
New Zealand White rabbits were injected subcutaneously with 20 mg/kg body weight of diethylnitrosamine (DEN), twice per week, starting when they were 1 week old. The animals were sacrificed 6 to 12 months after the first injection and lung tissues were processed for light microscopy. Using serotonin (5HT) and neuron specific enolase (NSE) as markers for the endocrine cells, tissue sections were stained immunocytochemically by the avidin-biotin complex method. Numerous neuroepithelial bodies (NEBs) positive for 5HT, but negative for NSE, were seen in the alveolar duct regions of DEN-treated rabbits. On the other hand, an increased number of solitary endocrine cells immunoreactive for NSE was found in bronchial or bronchiolar epithelia. The results indicate that DEN induced increases in two distinct types of endocrine cells: the component cells of NEBs are positive for 5HT and solitary cells are positive for NSE.
Disturbances in renal homeostatic function lead to changes in endocrine cell secretory activity. The aim of this study was the histomorphological estimation of dependence of gastric APUD system cell morphology and function on the time after subtotal nephrectomy in Wistar rats. Fragments of gastric pylorus were collected 1. 2, 4, and 6 weeks after nephrectomy. Paraffin sections were stained with H+E and by silver impregnation. Immunohistochemical reactions with the use of specific antibodies against calcitonin gene-related peptide (CGRP), synaptophysin (SPh). somatostatin (ST), and neuron-specific enolase (NSE) were also performed. Immunoreactivity of the examined substances in the pyloric mucosa in the first week after nephrectomy was lower than in the control group. However, in the following time intervals, endocrine cells showed stronger immunostaining in comparison with the control rats. The results suggest that chronic renal failure can modulate secretory activity of APUD system cells.
The presence of granular endocrine cells was investigated in the lungs of 4-6 weeks old Ringed Turtle Doves (Streptopelia risoria) by scanning and transmission electron microscopy. No granular cells were observed with the scanning electron microscope. In alternate semithin and ultrathin sections granular cells were found either singly or in small groups in the ciliated parts of the epithelium, and in relatively large clusters of between at least five and sixteen cells in the unciliated flat regions including the primary bronchus around the orifices of the lateroventral bronchi, and the roots of the medioventral, mediodorsal and lateroventral bronchi. Within the clusters the granular cells were frequently separated by attenuated profiles of highly electron-dense cells with microvilli. Naked axonal profiles which contained numerous agranular vesicles and occasional large granular vesicles were observed above the basal lamina lying close to the granular cells. Synaptic structures associated with the cells were found. This description of clusters of innervated granular endocrine cells in the dove appears to be the first account of neuroepithelial bodies in the lungs of birds.
We have studied the pattern of chromogranin A (CgA)-related species in different human endocrine cells that produce CgA and also express the calcitonin gene. Antibodies against CgA peptides that span its linear sequence were used in Western analysis of cell lines derived from medullary thyroid carcinoma (MTC), small cell lung cancers (SCLC), epidermoid cell lung cancer (ECLC) and a pulmonary carcinoid tumor (CRND). Each of the cell lines demonstrated a distinct pattern of CgA-related species. Gel filtration studies also revealed multiple and different forms of immunoreactive CgA in the cell lines. Although proteolysis may contribute to our results, these observations suggest that native CgA is processed to smaller species in a tissue-specific pattern by different endocrine cells. More conclusive studies, however, are necessary to establish that cell processing leads to the specific CgA moieties that we have observed.
The regional distributions and relative frequencies of some gastrointestinal endocrine cells in the three portions (cecum, colon and rectum) of the large intestinal tract of C57BL/6 mice were examined with immunohistochemical method using 7 types of specific antisera against chromogranin A (CGA), serotonin, somatostatin, human pancreatic polypeptide (HPP), glucagon, gastrin and cholecyctokinin (CCK)-8. In this study, all 3 types of immunoreactive (IR) cells were identified. Most of these IR cells in the large intestinal portion were generally spherical or spindle in shape (open-typed cell) while cells with a round shape (close-typed cell) were found in the intestinal gland. Their relative frequencies varied according to each portion of the large intestinal tract. CGA-IR cells were found throughout the whole large intestinal tract but were most predominant in the colon. Serotonin-IR cells were detected throughout the whole large intestinal tract and showed highest frequency in the colon. Peculiarly, glucagon-IR cells were restricted to the colon with a low frequency. However, no somatostatin-, HPP-, gastrin- and CCK-8-IR cells were found in the large intestinal tract. In conclusion, some peculiar distributional patterns of large intestinal endocrine cells were identified in C57BL/6 mice.