Orexin (hypocretin) appears to play a role in the regulation of energy balances. Previous reports have indicated that orexin-containing neurons are found only in the lateral hypothalamic (LH) area. We show that a subset of neurons in the gut which also express leptin receptors display orexin-like immunoreactivity and express functional orexin receptors. Orexin excites secretomotor neurons in the guinea pig submucosal plexus and increases motility. Moreover, fasting upregulates the phosphorylated form of cAMP response element-binding protein (pCREB) in orexin-immunoreactive neurons, indicating a functional response to food status in these cells. Together, these data suggest that orexin in the gut may play an even more intimate role in regulating energy homeostasis than it does in the CNS. (+info)
Presence of sorbin in human digestive tract and endocrine digestive tumours.
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BACKGROUND: Sorbin, a 153 amino acid peptide isolated from porcine intestine, was localised by immunohistochemistry in endocrine cells of the intestinal mucosa and pancreas and in the enteric nervous system in the pig. AIMS: To identify sorbin cells in normal human digestive tissues and to explore the expression of sorbin in 37 digestive endocrine tumours: 14 intestinal carcinoid tumours and 23 endocrine pancreatic tumours including six insulinomas. METHODS: Two polyclonal antibodies against the C-terminal and the N-terminal sequences of porcine sorbin raised in rabbit were used to evaluate sorbin expression by immunohistochemistry. RESULTS: In the human digestive tract, sorbin, characterised by both C-terminal and N-terminal immunoreactivity, was found in enterochromaffin cells of the gastric and intestinal epithelium from the pyloric junction to the descending colon. C-Terminal sorbin immunoreactivity alone was found in plexii from the enteric nervous system and in some insulin-containing cells of normal pancreas. C-Terminal and N-terminal antibodies disclosed sorbin in five of 14 intestinal carcinoid tumours; C-terminal antibody alone disclosed a C-terminal sorbin peptide in two of six insulinomas and three of 17 endocrine pancreatic tumours. The presence of sorbin was not associated with a specific clinical syndrome. CONCLUSIONS: Sorbin is present in the digestive tract in several forms. It is expressed in some intestinal and pancreatic endocrine tumours. (+info)
An immunohistochemical study of endocrine cells in the alimentary tract of the red-bellied frog, Bombina orientalis.
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The regional distribution and relative frequency of endocrine cells was studied immunohistochemically (PAP method) in the alimentary tract of the red-bellied frog, Bombina orientalis, using antisera against serotonin, somatostatin, chromogranin (CG), cholecystokinin (CCK)-8, bombesin, secretin, glucagon and pancreatic polypeptide (PP). Eight kinds of endocrine cells were identified in this study. These immunoreactive cells were located in the gastric glands of the stomach regions and in the intestinal or esophageal epithelium with variable frequencies. They were spherical or spindle-shaped. Serotonin- and somatostatin-immunoreactive cells were demonstrated in the whole alimentary tract including esophagus. CG-immunoreactive cells were restricted to the stomach. CCK-8-immunoreactive cells were observed from the antrum to the ileum. Bombesin-immunoreactive cells were restricted to the stomach. Secretin-immunoreactive cells were demonstrated in the pylorus, duodenum and ileum. Glucagon-immunoreactive cells were found in the antrum and duodenum. PP-immunoreactive cells were detected from the antrum to the rectum. In conclusion, throughout the alimentary tract of the red-bellied frog, the different regional distribution and relative frequency of endocrine cells were demonstrated. The regional distributions and relative frequencies of the endocrine cells in the alimentary tract of the red-bellied frog were resembled to those of the other anuran species except for esophagus. (+info)
Endocrine cells in the denervated intestine.
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This study deals with the effects of myenteric denervation of the proximal jejunum on endocrine cell population of the crypt-villus unit, 5 months after treatment with benzalkonium chloride (BAC). Male Wistar albino rats weighing on average 100 g were allocated to two groups: the BAC group - the proximal jejunal serosa was treated with 2 mM BAC for 30 min, and the control group - treated with saline solution (0,9% NaCl). There was a significant reduction in neurone number in the jejunal myenteric plexus of the BAC group and the endocrine cell population (serotoninergic and argyrophilic cells) was significantly increased in this intestine segment. In conclusion, the present findings provide further evidence that the myenteric denervation induced by BAC may lead to the development of a local imbalance of the neurotransmitters, with a consequent induction of enteroendocrine cell (argyrophilic and serotoninergic cells) hyperplasia in the crypt and villus. (+info)
Fatty acid-induced cholecystokinin secretion and changes in intracellular Ca2+ in two enteroendocrine cell lines, STC-1 and GLUTag.
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1. Fatty acid-induced cholecystokinin (CCK) secretion in humans and from the enteroendocrine cell line STC-1 depends critically on acyl chain length. 2. Therefore we have characterized the relationship between acyl chain length and the potency of the fatty acid to induce CCK secretion and changes in intracellular Ca2+ concentration ([Ca2+]i) in two enteroendocrine cell lines (STC-1 and GLUTag). We found that the potency of the fatty acid was directly proportional to its chain length and therefore inversely proportional to its solubility. 3. In both cell types, the fatty acid-induced rise in [Ca2+]i in response to decanoic acid (C10), dodecanoic acid (C12) and tetradecanoic acid (C14) was significantly reduced in Ca2+-free medium and largely blocked by nicardipine. Intracellular stores also contributed to the overall shape of the [Ca2+]i peak. Thus all the fatty acids tested caused the release of Ca2+ from stores and influx of extracellular Ca2+, presumably through L-type calcium channels. 4. To probe the site of fatty acid action, we studied the distribution of 14C-labelled dodecanoic acid. This label was rapidly and irreversibly accumulated by both cell types, where it became concentrated about 20-fold. Confocal microscopy of a fluorescent analogue of dodecanoic acid clearly demonstrated that it entered the cytosol and was not merely partitioning in the cell membrane. These data indicate that an intracellular action for fatty acid-induced CCK secretion cannot be eliminated. 5. Dodecanoic acid itself, and not a metabolite, is the agent responsible for triggering Ca2+ entry since a non-metabolizable form of dodecanoic acid (2-bromododecanoic acid) was also capable of inducing a rise in [Ca2+]i in both cell types. 6. In conclusion, the rise in [Ca2+]i in STC-1 and GLUTag cells evoked by medium- to long-chain fatty acids results from the triggering of a specific signalling pathway. Whether triggering occurs through activation of a membrane-bound receptor or at an intracellular site remains to be clarified. (+info)
Increased rectal mucosal enteroendocrine cells, T lymphocytes, and increased gut permeability following acute Campylobacter enteritis and in post-dysenteric irritable bowel syndrome.
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BACKGROUND AND AIMS: Post-dysenteric irritable bowel syndrome (PD-IBS) develops in up to 25% of patients following Campylobacter enteritis. Our aim was to define the pathological basis of this subgroup of IBS. METHODS: Twenty one patients (group 1) underwent serial rectal biopsy and gut permeability testing following acute Campylobacter enteritis as did 10 PD-IBS patients (group 2) and 12 asymptomatic controls. RESULTS: In group 1, enteroendocrine cell (EC) numbers were markedly increased initially and at six and 12 weeks (p<0.001) compared with controls. Gut permeability, as assessed by the lactulose/mannitol ratio, was significantly elevated, initially and at 12 weeks (p<0.005). CD3, CD4, and CD8 lymphocyte counts in the lamina propria and intraepithelial lymphocytes (IEL) were significantly increased initially compared with controls. At visit 1, EC numbers were positively correlated with CD3 counts (r=0.6, p=0.01). At one year, seven subjects (five with persistent loose stools) had rectal biopsies which showed significantly elevated EC, CD3, and IEL counts. In group 2, EC and IEL counts were significantly increased compared with controls (p<0.001), as was gut permeability (p<0.01). CONCLUSION: Increased EC, T lymphocytes, and gut permeability are acute changes following Campylobacter enteritis which can persist for more than a year and may contribute to PD-IBS. (+info)
Glucose-dependent insulin release from genetically engineered K cells.
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Genetic engineering of non-beta cells to release insulin upon feeding could be a therapeutic modality for patients with diabetes. A tumor-derived K-cell line was induced to produce human insulin by providing the cells with the human insulin gene linked to the 5'-regulatory region of the gene encoding glucose-dependent insulinotropic polypeptide (GIP). Mice expressing this transgene produced human insulin specifically in gut K cells. This insulin protected the mice from developing diabetes and maintained glucose tolerance after destruction of the native insulin-producing beta cells. (+info)
Differentiation of immature enterocytes into enteroendocrine cells by Pdx1 overexpression.
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The development of a variety of enteroendocrine cells of the gut is poorly understood. We tested whether immature intestinal stem cells were switched to multiple enteroendocrine hormone-producing cells by in vitro transfer of a homeobox gene. We transfected the pancreatic-duodenal homeobox 1 gene (Pdx1) into IEC-6 cells, an embryonic intestinal epithelial cell line derived from a normal rat, and selected the cells that overexpressed Pdx1 by 150-fold compared with control. The cells were examined for differentiation into enteroendocrine cells by immunocytochemical and electron microscopic analyses. Transfected cells cultured on micropore filters formed a trabecular network piled up on monolayer cells. These trabecular cells showed nuclear localization of Pdx1 protein and contained well-developed rough endoplasmic reticulum as well as many secretory granules of pleomorphic shape in the cytoplasm. Antibodies against chromogranin A, serotonin, cholecystokinin, gastrin, and somatostatin stained these secretory granules in the cytoplasm. Furthermore, immunofluorescence double staining analysis showed that different hormones were produced within a cell. These results provide the evidence that immature intestinal epithelial cells can differentiate into multiple hormone-producing enteroendocrine cells in response to overexpression of Pdx1. (+info)