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Persuy MA, Sanz G, Tromelin A, Thomas-Danguin T, Gibrat JF, Pajot-Augy E. Mammalian olfactory receptors: molecular mechanisms of odorant detection, 3D-modeling, and structure-activity relationships. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 130:1-36. [PMID: 25623335 DOI: 10.1016/bs.pmbts.2014.11.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
This chapter describes the main characteristics of olfactory receptor (OR) genes of vertebrates, including generation of this large multigenic family and pseudogenization. OR genes are compared in relation to evolution and among species. OR gene structure and selection of a given gene for expression in an olfactory sensory neuron (OSN) are tackled. The specificities of OR proteins, their expression, and their function are presented. The expression of OR proteins in locations other than the nasal cavity is regulated by different mechanisms, and ORs display various additional functions. A conventional olfactory signal transduction cascade is observed in OSNs, but individual ORs can also mediate different signaling pathways, through the involvement of other molecular partners and depending on the odorant ligand encountered. ORs are engaged in constitutive dimers. Ligand binding induces conformational changes in the ORs that regulate their level of activity depending on odorant dose. When present, odorant binding proteins induce an allosteric modulation of OR activity. Since no 3D structure of an OR has been yet resolved, modeling has to be performed using the closest G-protein-coupled receptor 3D structures available, to facilitate virtual ligand screening using the models. The study of odorant binding modes and affinities may infer best-bet OR ligands, to be subsequently checked experimentally. The relationship between spatial and steric features of odorants and their activity in terms of perceived odor quality are also fields of research that development of computing tools may enhance.
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Affiliation(s)
- Marie-Annick Persuy
- INRA UR 1197 NeuroBiologie de l'Olfaction, Domaine de Vilvert, Jouy-en-Josas, France
| | - Guenhaël Sanz
- INRA UR 1197 NeuroBiologie de l'Olfaction, Domaine de Vilvert, Jouy-en-Josas, France
| | - Anne Tromelin
- INRA UMR 1129 Flaveur, Vision et Comportement du Consommateur, Dijon, France
| | | | - Jean-François Gibrat
- INRA UR1077 Mathématique Informatique et Génome, Domaine de Vilvert, Jouy-en-Josas, France
| | - Edith Pajot-Augy
- INRA UR 1197 NeuroBiologie de l'Olfaction, Domaine de Vilvert, Jouy-en-Josas, France.
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102
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The brain-gut axis in health and disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 817:135-53. [PMID: 24997032 DOI: 10.1007/978-1-4939-0897-4_6] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The interaction between the brain and the gut has been recognized for many centuries. This bidirectional interaction occurs via neural, immunological and hormonal routes, and is important not only in normal gastrointestinal function but also plays a significant role in shaping higher cognitive function such as our feelings and our subconscious decision-making. Therefore, it remains unsurprising that perturbations in normal signalling have been associated with a multitude of disorders, including inflammatory and functional gastrointestinal disorders, and eating disorders.
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103
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Abstract
TRP channels are expressed in taste buds, nerve fibers, and keratinocytes in the oronasal cavity. These channels play integral roles in transducing chemical stimuli, giving rise to sensations of taste, irritation, warmth, coolness, and pungency. Specifically, TRPM5 acts downstream of taste receptors in the taste transduction pathway. TRPM5 channels convert taste-evoked intracellular Ca(2+) release into membrane depolarization to trigger taste transmitter secretion. PKD2L1 is expressed in acid-sensitive (sour) taste bud cells but is unlikely to be the transducer for sour taste. TRPV1 is a receptor for pungent chemical stimuli such as capsaicin and for several irritants (chemesthesis). It is controversial whether TRPV1 is present in the taste buds and plays a direct role in taste. Instead, TRPV1 is expressed in non-gustatory sensory afferent fibers and in keratinocytes of the oronasal cavity. In many sensory fibers and epithelial cells lining the oronasal cavity, TRPA1 is also co-expressed with TRPV1. As with TRPV1, TRPA1 transduces a wide variety of irritants and, in combination with TRPV1, assures that there is a broad response to noxious chemical stimuli. Other TRP channels, including TRPM8, TRPV3, and TRPV4, play less prominent roles in chemesthesis and no known role in taste, per se. The pungency of foods and beverages is likely highly influenced by the temperature at which they are consumed, their acidity, and, for beverages, their carbonation. All these factors modulate the activity of TRP channels in taste buds and in the oronasal mucosa.
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Affiliation(s)
- Stephen D Roper
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, 1600 NW 10th Ave., Miami, FL, 33136, USA,
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104
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Bala V, Rajagopal S, Kumar DP, Nalli AD, Mahavadi S, Sanyal AJ, Grider JR, Murthy KS. Release of GLP-1 and PYY in response to the activation of G protein-coupled bile acid receptor TGR5 is mediated by Epac/PLC-ε pathway and modulated by endogenous H2S. Front Physiol 2014; 5:420. [PMID: 25404917 PMCID: PMC4217307 DOI: 10.3389/fphys.2014.00420] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 10/11/2014] [Indexed: 12/19/2022] Open
Abstract
Activation of plasma membrane TGR5 receptors in enteroendocrine cells by bile acids is known to regulate gastrointestinal secretion and motility and glucose homeostasis. The endocrine functions of the gut are modulated by microenvironment of the distal gut predominantly by sulfur-reducing bacteria of the microbiota that produce H2S. However, the mechanisms involved in the release of peptide hormones, GLP-1 and PYY in response to TGR5 activation by bile acids and the effect of H2S on bile acid-induced release of GLP-1 and PYY are unclear. In the present study, we have identified the signaling pathways activated by the bile acid receptor TGR5 to mediate GLP-1 and PYY release and the mechanism of inhibition of their release by H2S in enteroendocrine cells. The TGR5 ligand oleanolic acid (OA) stimulated Gαs and cAMP formation, and caused GLP-1 and PYY release. OA-induced cAMP formation and peptide release were blocked by TGR5 siRNA. OA also caused an increase in PI hydrolysis and intracellular Ca2+. Increase in PI hydrolysis was abolished in cells transfected with PLC-ε siRNA. 8-pCPT-2′-O-Me-cAMP, a selective activator of Epac, stimulated PI hydrolysis, and GLP-1 and PYY release. L-Cysteine, which activates endogenous H2S producing enzymes cystathionine-γ-lyase and cystathionine-β-synthase, and NaHS and GYY4137, which generate H2S, inhibited PI hydrolysis and GLP-1 and PYY release in response to OA or 8-pCPT-2′-O-Me-cAMP. Propargylglycine, an inhibitor of CSE, reversed the effect of L-cysteine on PI hydrolysis and GLP-1 and PYY release. We conclude: (i) activation of Gαs-coupled TGR5 receptors causes stimulation of PI hydrolysis, and release of GLP-1 and PYY via a PKA-independent, cAMP-dependent mechanism involving Epac/PLC-ε/Ca2+ pathway, and (ii) H2S has potent inhibitory effects on GLP-1 and PYY release in response to TGR5 activation, and the mechanism involves inhibition of PLC-ε/Ca2+ pathway.
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Affiliation(s)
- Vanitha Bala
- Gastroenterology Division, Department of Internal Medicine, Virginia Commonwealth University Richmond, VA, USA
| | - Senthilkumar Rajagopal
- Department of Physiology, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University Richmond, VA, USA
| | - Divya P Kumar
- Department of Physiology, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University Richmond, VA, USA
| | - Ancy D Nalli
- Department of Physiology, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University Richmond, VA, USA
| | - Sunila Mahavadi
- Department of Physiology, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University Richmond, VA, USA
| | - Arun J Sanyal
- Gastroenterology Division, Department of Internal Medicine, Virginia Commonwealth University Richmond, VA, USA
| | - John R Grider
- Department of Physiology, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University Richmond, VA, USA
| | - Karnam S Murthy
- Department of Physiology, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University Richmond, VA, USA
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105
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Appleby RN, Walters JRF. The role of bile acids in functional GI disorders. Neurogastroenterol Motil 2014; 26:1057-69. [PMID: 24898156 DOI: 10.1111/nmo.12370] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 04/28/2014] [Indexed: 02/06/2023]
Abstract
BACKGROUND Bile acids are increasingly implicated in the pathogenesis of functional GI disorders. New mechanisms have recently been described in the irritable bowel syndrome, chronic diarrhea and chronic idiopathic constipation. Identification of bile acid signaling through farnesoid X receptor (FXR), transmembrane G-coupled receptor 5 (TGR5) and fibroblast growth factor 19 (FGF19) has led to the development of new, directly acting therapeutic agents. Despite these advances primary bile acid diarrhea remains under-recognized partly because of the lack of a widely available diagnostic test. PURPOSE In this review we will summarize the effects of bile acids on bowel function throughout the gastrointestinal tract and their roles in the pathogenesis of functional diseases. We will review established diagnostic tests and therapies for functional heartburn, dyspepsia and bile acid diarrhea. There will be a particular emphasis on recent trial data for emerging therapies such as Elobixibat and Obeticholic acid and novel diagnostic tests for bile acid diarrhea such as 7α-Hydroxy-4-cholesten-3-one (C4) and FGF19. Finally we will discuss future directions for research in this rapidly evolving field, such as bacterial bile acid modification and identification of genetic anomalies associated with functional disorders.
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Affiliation(s)
- Richard N Appleby
- Section of Hepatology and Gastroenterology, Imperial College London, Imperial College Healthcare, Hammersmith Hospital, London, UK
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106
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Kidd M, Modlin IM, Drozdov I. Gene network-based analysis identifies two potential subtypes of small intestinal neuroendocrine tumors. BMC Genomics 2014; 15:595. [PMID: 25023465 PMCID: PMC4124138 DOI: 10.1186/1471-2164-15-595] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 07/07/2014] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Tumor transcriptomes contain information of critical value to understanding the different capacities of a cell at both a physiological and pathological level. In terms of clinical relevance, they provide information regarding the cellular "toolbox" e.g., pathways associated with malignancy and metastasis or drug dependency. Exploration of this resource can therefore be leveraged as a translational tool to better manage and assess neoplastic behavior. The availability of public genome-wide expression datasets, provide an opportunity to reassess neuroendocrine tumors at a more fundamental level. We hypothesized that stringent analysis of expression profiles as well as regulatory networks of the neoplastic cell would provide novel information that facilitates further delineation of the genomic basis of small intestinal neuroendocrine tumors. RESULTS We re-analyzed two publically available small intestinal tumor transcriptomes using stringent quality control parameters and network-based approaches and validated expression of core secretory regulatory elements e.g., CPE, PCSK1, secretogranins, including genes involved in depolarization e.g., SCN3A, as well as transcription factors associated with neurodevelopment (NKX2-2, NeuroD1, INSM1) and glucose homeostasis (APLP1). The candidate metastasis-associated transcription factor, ST18, was highly expressed (>14-fold, p < 0.004). Genes previously associated with neoplasia, CEBPA and SDHD, were decreased in expression (-1.5 - -2, p < 0.02). Genomic interrogation indicated that intestinal tumors may consist of two different subtypes, serotonin-producing neoplasms and serotonin/substance P/tachykinin lesions. QPCR validation in an independent dataset (n = 13 neuroendocrine tumors), confirmed up-regulated expression of 87% of genes (13/15). CONCLUSIONS An integrated cellular transcriptomic analysis of small intestinal neuroendocrine tumors identified that they are regulated at a developmental level, have key activation of hypoxic pathways (a known regulator of malignant stem cell phenotypes) as well as activation of genes involved in apoptosis and proliferation. Further refinement of these analyses by RNAseq studies of large-scale databases will enable definition of individual master regulators and facilitate the development of novel tissue and blood-based tools to better understand diagnose and treat tumors.
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Affiliation(s)
- Mark Kidd
- Yale University School of Medicine, New Haven, CT 06510, USA.
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107
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Serum and ascitic fluid serotonin levels and 5-hydroxyindoleacetic acid urine excretion in the liver of cirrhotic patients with encephalopathy. Adv Med Sci 2014; 58:251-6. [PMID: 24384770 DOI: 10.2478/ams-2013-0010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
PURPOSE The excess and deficit of serotonin can be the cause of somatic and mental disorders. The aim of this study was to evaluate serotonin levels in blood and ascitic fluid as well as excretion of 5-hydroxyindoleacetic acid (5-HIAA) in urine in patients with hepatic encephalopathy (HE). MATERIAL AND METHODS The study included 75 alcoholic cirrhotic patients divided into 3 groups (HE1, HE2, HE3), 25 patients each, with grade 1, 2 and 3 of hepatic encephalopathy according to West-Haven classification. The control group (C) included 25 clinically healthy volunteers. Venous blood and ascitic fluid were collected in fasting. On the same day a 24-hour urine collection was performed. Immunoenzymatic method was used to determine the serotonin level in serum and ascitic fluid, and 5-HIAA in urine (IBL-RE-59121, RE-59131). RESULTS In the control group, mean serum serotonin level (ng/ml) was 155.5 ± 38.1 and in the 3 study groups: HE1 - 175.2 ± 32.4 (NS), HE2 - 137.2 ± 28.6 (NS), HE3 - 108.3 ± 46.3 (p<0.001). Serotonin concentration in ascitic fluid was on the average about 25% of its level in serum. The excretion of 5-HIAA in urine (mg/24h) in all groups, was: C - 5.9 ± 2.1, HE1 - 5.8 ± 1.8 (NS), HE2 - 4.8 ± 1.2(NS), HE3 - 4.3 ± 1.3 (p<0.05). CONCLUSION The results of our study indicate that serum and ascitic fluid level of serotonin and urine excretion of 5-HIAA depends on the grade of hepatic encephalopathy. In patients with severe hepatic encephalopathy serotonin concentration in blood is decreased which can affect some clinical manifestation of this disease.
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108
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Lee YJ, Park KS. Irritable bowel syndrome: Emerging paradigm in pathophysiology. World J Gastroenterol 2014; 20:2456-2469. [PMID: 24627583 PMCID: PMC3949256 DOI: 10.3748/wjg.v20.i10.2456] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 12/01/2013] [Accepted: 02/20/2014] [Indexed: 02/06/2023] Open
Abstract
Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders, characterized by abdominal pain, bloating, and changes in bowel habits. These symptoms cannot be explained by structural abnormalities and there is no specific laboratory test or biomarker for IBS. Therefore, IBS is classified as a functional disorder with diagnosis dependent on the history taking about manifested symptoms and careful physical examination. Although a great deal of research has been carried out in this area, the pathophysiology of IBS is complex and not completely understood. Multiple factors are thought to contribute to the symptoms in IBS patients; altered gastrointestinal motility, visceral hypersensitivity, and the brain-gut interaction are important classical concepts in IBS pathophysiology. New areas of research in this arena include inflammation, postinfectious low-grade inflammation, genetic and immunologic factors, an altered microbiota, dietary factors, and enteroendocrine cells. These emerging studies have not shown consistent results, provoking controversy in the IBS field. However, certain lines of evidence suggest that these mechanisms are important at least a subset of IBS patients, confirming that IBS symptoms cannot be explained by a single etiological mechanism. Therefore, it is important to keep in mind that IBS requires a more holistic approach to determining effective treatment and understanding the underlying mechanisms.
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109
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Ikehara O, Hayashi H, Waguri T, Kaji I, Karaki SI, Kuwahara A, Suzuki Y. Luminal trypsin induces enteric nerve-mediated anion secretion in the mouse cecum. J Physiol Sci 2014; 64:119-28. [PMID: 24421180 PMCID: PMC10717537 DOI: 10.1007/s12576-013-0302-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 12/10/2013] [Indexed: 02/08/2023]
Abstract
Proteases play a diverse role in health and disease. An excessive concentration of proteases has been found in the feces of patients with inflammatory bowel disease or irritable bowel syndrome and been implicated in the pathogenesis of such disorders. This study examined the effect of the serine protease, trypsin, on intestinal epithelial anion secretion when added to the luminal side. A mucosal-submucosal sheet of the mouse cecum was mounted in Ussing chambers, and the short-circuit current (I sc) was measured. Trypsin added to the mucosal (luminal) side increased I sc with an ED50 value of approximately 10 μM. This I sc increase was suppressed by removing Cl(-) from the bathing solution. The I sc increase induced by 10-100 μM trypsin was substantially suppressed by tetrodotoxin, and partially inhibited by a neurokinin-1 receptor antagonist, but not by a muscarinic or nicotinic ACh-receptor antagonist. The trypsin-induced I sc increase was also significantly inhibited by a 5-hydroxytryptamine-3 receptor (5-HT3) antagonist and substantially suppressed by the simultaneous addition of both 5-HT3 and 5-HT4 receptor antagonists. We conclude that luminal trypsin activates the enteric reflex to induce anion secretion, 5-HT and substance P playing important mediating roles in this secreto-motor reflex. Luminal proteases may contribute to the cause of diarrhea occurring with some intestinal disorders.
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Affiliation(s)
- Osamu Ikehara
- Laboratory of Physiology, Department of Food and Nutritional Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka, 422-8526 Japan
| | - Hisayoshi Hayashi
- Laboratory of Physiology, Department of Food and Nutritional Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka, 422-8526 Japan
| | - Toshiharu Waguri
- Laboratory of Physiology, Department of Food and Nutritional Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka, 422-8526 Japan
| | - Izumi Kaji
- Laboratory of Physiology, Department of Environmental Health Sciences, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka, 422-8526 Japan
| | - Shin-ichiro Karaki
- Laboratory of Physiology, Department of Environmental Health Sciences, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka, 422-8526 Japan
| | - Atsukazu Kuwahara
- Laboratory of Physiology, Department of Environmental Health Sciences, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka, 422-8526 Japan
| | - Yuichi Suzuki
- Laboratory of Physiology, Department of Food and Nutritional Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka, 422-8526 Japan
- Laboratory of Anatomy and Physiology, Department of Health and Nutrition, Sendai Shirayuri Women’s College, Hondacho 6-1, Izumi-ku, Sendai, 981-3107 Japan
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110
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Watanabe H, Saito R, Nakano T, Takahashi H, Takahashi Y, Sumiyoshi K, Sato K, Chen X, Okada N, Iwasaki S, Harjanti DW, Sekiguchi N, Sano H, Kitazawa H, Rose MT, Ohwada S, Watanabe K, Aso H. Effect of peripheral 5-HT on glucose and lipid metabolism in wether sheep. PLoS One 2014; 9:e88058. [PMID: 24505376 PMCID: PMC3913723 DOI: 10.1371/journal.pone.0088058] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 01/06/2014] [Indexed: 11/18/2022] Open
Abstract
In mice, peripheral 5-HT induces an increase in the plasma concentrations of glucose, insulin and bile acids, and a decrease in plasma triglyceride, NEFA and cholesterol concentrations. However, given the unique characteristics of the metabolism of ruminants relative to monogastric animals, the physiological role of peripheral 5-HT on glucose and lipid metabolism in sheep remains to be established. Therefore, in this study, we investigated the effect of 5-HT on the circulating concentrations of metabolites and insulin using five 5-HT receptor (5HTR) antagonists in sheep. After fasting for 24 h, sheep were intravenously injected with 5-HT, following which-, plasma glucose, insulin, triglyceride and NEFA concentrations were significantly elevated. In contrast, 5-HT did not affect the plasma cholesterol concentration, and it induced a decrease in bile acid concentrations. Increases in plasma glucose and insulin concentrations induced by 5-HT were attenuated by pre-treatment with Methysergide, a 5HTR 1, 2 and 7 antagonist. Additionally, decreased plasma bile acid concentrations induced by 5-HT were blocked by pre-treatment with Ketanserin, a 5HTR 2A antagonist. However, none of the 5HTR antagonists inhibited the increase in plasma triglyceride and NEFA levels induced by 5-HT. On the other hand, mRNA expressions of 5HTR1D and 1E were observed in the liver, pancreas and skeletal muscle. These results suggest that there are a number of differences in the physiological functions of peripheral 5-HT with respect to lipid metabolism between mice and sheep, though its effect on glucose metabolism appears to be similar between these species.
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Affiliation(s)
- Hitoshi Watanabe
- Cellar Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Ryo Saito
- Cellar Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Tatsuya Nakano
- Cellar Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Hideyuki Takahashi
- Cellar Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Yu Takahashi
- Cellar Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Keisuke Sumiyoshi
- Cellar Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Katsuyoshi Sato
- Cellar Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Xiangning Chen
- Cellar Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Natsumi Okada
- Cellar Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Shunsuke Iwasaki
- Cellar Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Dian W Harjanti
- Department of Animal Sciences, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Natsumi Sekiguchi
- Department of Animal Sciences, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Hiroaki Sano
- Department of Animal Sciences, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Haruki Kitazawa
- Laboratory of Food and Biomolecular Science, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Michael T Rose
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Cardiganshire, United Kingdom
| | - Shyuichi Ohwada
- Cellar Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Kouichi Watanabe
- Cellar Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Hisashi Aso
- Cellar Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
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111
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Promotion of cancer cell invasiveness and metastasis emergence caused by olfactory receptor stimulation. PLoS One 2014; 9:e85110. [PMID: 24416348 PMCID: PMC3885679 DOI: 10.1371/journal.pone.0085110] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 12/01/2013] [Indexed: 12/14/2022] Open
Abstract
Olfactory receptors (ORs) are expressed in the olfactory epithelium, where they detect odorants, but also in other tissues with additional functions. Some ORs are even overexpressed in tumor cells. In this study, we identified ORs expressed in enterochromaffin tumor cells by RT-PCR, showing that single cells can co-express several ORs. Some of the receptors identified were already reported in other tumors, but they are orphan (without known ligand), as it is the case for most of the hundreds of human ORs. Thus, genes coding for human ORs with known ligands were transfected into these cells, expressing functional heterologous ORs. The in vitro stimulation of these cells by the corresponding OR odorant agonists promoted cell invasion of collagen gels. Using LNCaP prostate cancer cells, the stimulation of the PSGR (Prostate Specific G protein-coupled Receptor), an endogenously overexpressed OR, by β-ionone, its odorant agonist, resulted in the same phenotypic change. We also showed the involvement of a PI3 kinase γ dependent signaling pathway in this promotion of tumor cell invasiveness triggered by OR stimulation. Finally, after subcutaneous inoculation of LNCaP cells into NSG immunodeficient mice, the in vivo stimulation of these cells by the PSGR agonist β-ionone significantly enhanced metastasis emergence and spreading.
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112
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Wang HH, Xie NN, Li QY, Hu YQ, Ren JL, Guleng B. Exome sequencing revealed novel germline mutations in Chinese Peutz-Jeghers syndrome patients. Dig Dis Sci 2014; 59:64-71. [PMID: 24154639 DOI: 10.1007/s10620-013-2875-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 09/02/2013] [Indexed: 12/20/2022]
Abstract
BACKGROUND AND AIMS Peutz-Jeghers Syndrome (PJS) is an autosomal dominant disorder which predisposes to the development of various cancers. Germline mutation in the serine/threonine kinase 11 gene (STK11) is known as one of the major causes of PJS. However, a notable proportion of PJS samples do not carry any mutation in STK11, suggesting possible genetic heterogeneity in the disease and the existence of other causative variants. METHODS AND RESULTS In order to identify other germline variants in the coding regions of the genome that are associated with PJS, we performed exome sequencing in three Chinese individuals with PJS and identified 16 common germline variants (12 protein-coding including STK11, 4 in pre-microRNAs). We further validated protein-coding variants in six PJS individuals (three with wild-type STK11) and predicted the functional impact. As result, we found that 7 coding variants are likely to have functional impacts. Especially, we identified 2 new germline variants which are represented in all six PJS samples and are independent of STK11 mutation. CONCLUSIONS Our study provided an exomic view of PJS. The germline variants identified in our analysis may help to resolve the complex genetic background of the disease and thus lead to the discovery of novel causative variants of PJS.
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Affiliation(s)
- Huan-Huan Wang
- Department of Gastroenterology, Zhongshan Hospital Affiliated to Xiamen University, 201 Hubin South Road, Xiamen, 361004, Fujian, China
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113
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Taste Receptor Gene Expression Outside the Gustatory System. TOPICS IN MEDICINAL CHEMISTRY 2014. [DOI: 10.1007/7355_2014_79] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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114
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Transcriptomic analysis of the bitter taste receptor-mediated glucagon-like peptide-1 stimulation effect of quinine. BIOCHIP JOURNAL 2013. [DOI: 10.1007/s13206-013-7410-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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115
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Raghupathi R, Duffield MD, Zelkas L, Meedeniya A, Brookes SJH, Sia TC, Wattchow DA, Spencer NJ, Keating DJ. Identification of unique release kinetics of serotonin from guinea-pig and human enterochromaffin cells. J Physiol 2013; 591:5959-75. [PMID: 24099799 PMCID: PMC3872764 DOI: 10.1113/jphysiol.2013.259796] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 10/02/2013] [Indexed: 12/21/2022] Open
Abstract
The major source of serotonin (5-HT) in the body is the enterochromaffin (EC) cells lining the intestinal mucosa of the gastrointestinal tract. Despite the fact that EC cells synthesise ∼95% of total body 5-HT, and that this 5-HT has important paracrine and endocrine roles, no studies have investigated the mechanisms of 5-HT release from single primary EC cells. We have developed a rapid primary culture of guinea-pig and human EC cells, allowing analysis of single EC cell function using electrophysiology, electrochemistry, Ca(2+) imaging, immunocytochemistry and 3D modelling. Ca(2+) enters EC cells upon stimulation and triggers quantal 5-HT release via L-type Ca(2+) channels. Real time amperometric techniques reveal that EC cells release 5-HT at rest and this release increases upon stimulation. Surprisingly for an endocrine cell storing 5-HT in large dense core vesicles (LDCVs), EC cells release 70 times less 5-HT per fusion event than catecholamine released from similarly sized LDCVs in endocrine chromaffin cells, and the vesicle release kinetics instead resembles that observed in mammalian synapses. Furthermore, we measured EC cell density along the gastrointestinal tract to create three-dimensional (3D) simulations of 5-HT diffusion using the minimal number of variables required to understand the physiological relevance of single cell 5-HT release in the whole-tissue milieu. These models indicate that local 5-HT levels are likely to be maintained around the activation threshold for mucosal 5-HT receptors and that this is dependent upon stimulation and location within the gastrointestinal tract. This is the first study demonstrating single cell 5-HT release in primary EC cells. The mode of 5-HT release may represent a unique mode of exocytosis amongst endocrine cells and is functionally relevant to gastrointestinal sensory and motor function.
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Affiliation(s)
- Ravinarayan Raghupathi
- D. Keating: Department of Human Physiology and Centre for Neuroscience, Flinders University, Sturt Road, Adelaide, 5001, Australia.
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Steinbach S, Reindl W, Dempfle A, Schuster A, Wolf P, Hundt W, Huber W. Smell and taste in inflammatory bowel disease. PLoS One 2013; 8:e73454. [PMID: 24086282 PMCID: PMC3783456 DOI: 10.1371/journal.pone.0073454] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 07/21/2013] [Indexed: 01/07/2023] Open
Abstract
Objective To investigate the olfactory/gustatory functions of patients with inflammatory bowel disease (IBD) by smell/taste tests, and to determine if disease activity or medication might influence the olfactory/gustatory functions of patients. Patients and Methods In total, 59 IBD patients (37 Crohn's disease (CD) and 22 ulcerative colitis (UC) patients) were studied using “Sniffin' sticks” and “taste strips” for olfactory and gustatory tests, respectively, and compared to healthy controls and published normative data. Results Among IBD (CD and UC) patients, the values for odor threshold, but not for odor identification or discrimination, were significantly lower than that of the normative data. Further, these patients showed lower values than the normative taste values and the control group for all tastes, except sour; 57.6% of the IBD patients were hyposmic, while 30.5% were hypogeusic. Subjective self-assessments showed that the patients were not aware of their reduced olfactory/gustatory functions. There were no relevant differences in taste and smell abilities between the CD and UC patients. Disease activity and treatment did not influence the olfactory/gustatory functions. Conclusion IBD (CD and UC) patients exhibited significant reductions in the olfactory and gustatory functions. Therefore, patients should be tested by smell/taste tests, in order to be adequately informed of their olfactory/gustatory functions and provided an understanding of how to overcome their limitations, and thus improve their quality of life.
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Affiliation(s)
- Silke Steinbach
- Department of Otorhinolaryngology, Philipps-University, Marburg, Germany
- * E-mail:
| | - Wolfgang Reindl
- Medizinische Klinik (Department of Gastroenterology), Klinikum rechts der Isar, Technische Universitaet Muenchen, Munich, Germany
| | - Astrid Dempfle
- Institut für medizinische Biometrie und Epidemiologie (Institute of Medical Biometry and Epidemiology), Philipps-University, Marburg, Germany
| | - Anna Schuster
- Medizinische Klinik (Department of Gastroenterology), Klinikum rechts der Isar, Technische Universitaet Muenchen, Munich, Germany
| | - Petra Wolf
- Institut für medizinische Statistik und Epidemiologie (Department of Medical Statistics and Epidemiology), Klinikum rechts der Isar, Technische Universitaet Muenchen, Munich, Germany
| | - Walter Hundt
- Department of Radiology, Philipps-University, Marburg, Germany
| | - Wolfgang Huber
- Medizinische Klinik (Department of Gastroenterology), Klinikum rechts der Isar, Technische Universitaet Muenchen, Munich, Germany
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Reichardt F, Baudry C, Gruber L, Mazzuoli G, Moriez R, Scherling C, Kollmann P, Daniel H, Kisling S, Haller D, Neunlist M, Schemann M. Properties of myenteric neurones and mucosal functions in the distal colon of diet-induced obese mice. J Physiol 2013; 591:5125-39. [PMID: 23940384 DOI: 10.1113/jphysiol.2013.262733] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Colonic transit and mucosal integrity are believed to be impaired in obesity. However, a comprehensive assessment of altered colonic functions, inflammatory changes and neuronal signalling of obese animals is missing. In mice, we studied the impact of diet-induced obesity (DIO) on: (i) in vivo colonic transit; (ii) signalling in the myenteric plexus by recording responses to nicotine and 2-methyl-5-hydroxytryptamine (2-methyl-5-HT), together with the expression of tryptophan hydroxylase (TPH) 1 and 2, serotonin reuptake transporter, choline acetyltransferase and the paired box gene 4; and (iii) expression of proinflammatory cytokines, epithelial permeability and density of macrophages, mast cells and enterochromaffin cells. Compared with controls, colon transit and neuronal sensitivity to nicotine and 2-methyl-5-HT were enhanced in DIO mice fed for 12 weeks. This was associated with increased tissue acetylcholine and 5-hydroxytryptamine (5-HT) content, and increased expression of TPH1 and TPH2. In DIO mice, upregulation of proinflammatory cytokines was found in fat tissue, but not in the gut wall. Accordingly, mucosal permeability or integrity was unaltered without signs of immune cell infiltration in the gut wall. Body weight showed positive correlations with adipocyte markers, tissue levels of 5-HT and acetylcholine, and the degree of neuronal sensitization. DIO mice fed for 4 weeks showed no neuronal sensitization, had no signs of gut wall inflammation and showed a smaller increase in leptin, interleukin-6 and monocyte chemoattractant protein 1 expression in fat tissue. DIO is associated with faster colonic transit and impacts on acetylcholine and 5-HT metabolism with enhanced responsiveness of enteric neurones to both mediators after 12 weeks of feeding. Our study demonstrates neuronal plasticity in DIO prior to the development of a pathological histology or abnormal mucosal functions. This questions the common assumption that increased mucosal inflammation and permeability initiate functional disorders in obesity.
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Affiliation(s)
- François Reichardt
- Professor M. Schemann: Lehrstuhl für Humanbiologie, Technische Universität München, Liesel-Beckmann-Straße 4, 85350 Freising-Weihenstephan, Germany.
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Elvira B, Honisch S, Almilaji A, Pakladok T, Liu G, Shumilina E, Alesutan I, Yang W, Munoz C, Lang F. Up-regulation of Na(+)-coupled glucose transporter SGLT1 by caveolin-1. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2394-8. [PMID: 23774524 DOI: 10.1016/j.bbamem.2013.06.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 05/29/2013] [Accepted: 06/06/2013] [Indexed: 01/09/2023]
Abstract
The Na(+)-coupled glucose transporter SGLT1 (SLC5A1) accomplishes concentrative cellular glucose uptake even at low extracellular glucose concentrations. The carrier is expressed in renal proximal tubules, small intestine and a variety of nonpolarized cells including several tumor cells. The present study explored whether SGLT1 activity is regulated by caveolin-1, which is known to regulate the insertion of several ion channels and carriers in the cell membrane. To this end, SGLT1 was expressed in Xenopus oocytes with or without additional expression of caveolin-1 and electrogenic glucose transport determined by dual electrode voltage clamp experiments. In SGLT1-expressing oocytes, but not in oocytes injected with water or caveolin-1 alone, the addition of glucose to the extracellular bath generated an inward current (Ig), which was increased following coexpression of caveolin-1. Kinetic analysis revealed that caveolin-1 increased maximal Ig without significantly modifying the glucose concentration required to trigger half maximal Ig (KM). According to chemiluminescence and confocal microscopy, caveolin-1 increased SGLT1 protein abundance in the cell membrane. Inhibition of SGLT1 insertion by brefeldin A (5μM) resulted in a decline of Ig, which was similar in the absence and presence of caveolin-1. In conclusion, caveolin-1 up-regulates SGLT1 activity by increasing carrier protein abundance in the cell membrane, an effect presumably due to stimulation of carrier protein insertion into the cell membrane.
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Affiliation(s)
- Bernat Elvira
- Department of Physiology, University of Tübingen, Gmelinstr. 5, D-72076 Tübingen, Germany
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119
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Damen R, Haugen M, Svejda B, Alaimo D, Brenna O, Pfragner R, Gustafsson BI, Kidd M. The stimulatory adenosine receptor ADORA2B regulates serotonin (5-HT) synthesis and release in oxygen-depleted EC cells in inflammatory bowel disease. PLoS One 2013; 8:e62607. [PMID: 23638125 PMCID: PMC3637445 DOI: 10.1371/journal.pone.0062607] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 03/27/2013] [Indexed: 12/11/2022] Open
Abstract
OBJECTIVE We recently demonstrated that hypoxia, a key feature of IBD, increases enterochromaffin (EC) cell 5-HT secretion, which is also physiologically regulated by the ADORA2B mechanoreceptor. Since hypoxia is associated with increased extracellular adenosine, we wanted to examine whether this nucleotide amplifies HIF-1α-mediated 5-HT secretion. DESIGN The effects of hypoxia were studied on IBD mucosa, isolated IBD-EC cells, isolated normal EC cells and the EC cell tumor derived cell line KRJ-1. Hypoxia (0.5% O2) was compared to NECA (adenosine agonist), MRS1754 (ADORA2B receptor antagonist) and SCH442146 (ADORA2A antagonist) on HIF signaling and 5-HT secretion. Antisense approaches were used to mechanistically evaluate EC cells in vitro. PCR and western blot were used to analyze transcript and protein levels of HIF-1α signaling and neuroendocrine cell function. An animal model of colitis was evaluated to confirm hypoxia:adenosine signaling in vivo. RESULTS HIF-1α is upregulated in IBD mucosa and IBD-EC cells, the majority (~90%) of which express an activated phenotype in situ. Hypoxia stimulated 5-HT release maximally at 30 mins, an effect amplified by NECA and selectively inhibited by MRS1754, through phosphorylation of TPH-1 and activation of VMAT-1. Transient transfection with Renilla luciferase under hypoxia transcriptional response element (HRE) control identified that ADORA2B activated HIF-1α signaling under hypoxic conditions. Additional signaling pathways associated with hypoxia:adenosine included MAP kinase and CREB. Antisense approaches mechanistically confirmed that ADORA2B signaling was linked to these pathways and 5-HT release under hypoxic conditions. Hypoxia:adenosine activation which could be reversed by 5'-ASA treatment was confirmed in a TNBS-model. CONCLUSION Hypoxia induced 5-HT synthesis and secretion is amplified by ADORA2B signaling via MAPK/CREB and TPH-1 activation. Targeting ADORA2s may decrease EC cell 5-HT production and secretion in IBD.
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Affiliation(s)
- Rikard Damen
- Gastrointestinal Pathobiology Research Group, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Martin Haugen
- Gastrointestinal Pathobiology Research Group, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Bernhard Svejda
- Gastrointestinal Pathobiology Research Group, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Daniele Alaimo
- Gastrointestinal Pathobiology Research Group, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Oystein Brenna
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Roswitha Pfragner
- Institute of Pathophysiology and Immunology, Centre for Molecular Medicine, Graz, Austria
| | - Bjorn I. Gustafsson
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Mark Kidd
- Gastrointestinal Pathobiology Research Group, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
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Donovan MH, Tecott LH. Serotonin and the regulation of mammalian energy balance. Front Neurosci 2013; 7:36. [PMID: 23543912 PMCID: PMC3608917 DOI: 10.3389/fnins.2013.00036] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 03/03/2013] [Indexed: 01/17/2023] Open
Abstract
Maintenance of energy balance requires regulation of the amount and timing of food intake. Decades of experiments utilizing pharmacological and later genetic manipulations have demonstrated the importance of serotonin signaling in this regulation. Much progress has been made in recent years in understanding how central nervous system (CNS) serotonin systems acting through a diverse array of serotonin receptors impact feeding behavior and metabolism. Particular attention has been paid to mechanisms through which serotonin impacts energy balance pathways within the hypothalamus. How upstream factors relevant to energy balance regulate the release of hypothalamic serotonin is less clear, but work addressing this issue is underway. Generally, investigation into the central serotonergic regulation of energy balance has had a predominantly “hypothalamocentric” focus, yet non-hypothalamic structures that have been implicated in energy balance regulation also receive serotonergic innervation and express multiple subtypes of serotonin receptors. Moreover, there is a growing appreciation of the diverse mechanisms through which peripheral serotonin impacts energy balance regulation. Clearly, the serotonergic regulation of energy balance is a field characterized by both rapid advances and by an extensive and diverse set of central and peripheral mechanisms yet to be delineated.
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Affiliation(s)
- Michael H Donovan
- Department of Psychiatry, University of California San Francisco CA, USA
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121
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Chen YL, Huang XQ, Xu SJ, Liao JB, Wang RJ, Lu XF, Xie YL, Zhou FS, Su ZR, Lai XP. Relieving visceral hyperalgesia effect of Kangtai capsule and its potential mechanisms via modulating the 5-HT and NO level in vivo. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2013; 20:249-257. [PMID: 23141427 DOI: 10.1016/j.phymed.2012.09.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 08/18/2012] [Accepted: 09/21/2012] [Indexed: 06/01/2023]
Abstract
Kangtai capsule (KT) is one type of traditional Chinese medicine preparation derived from the proved recipe, which was frequently applied as an effective clinical treatment of IBS. However, there still lack the reasonable and all-round analytical approach and the scientific studies on its underlying mechanisms. Therefore, our study aimed to develop the novel method for evaluating its quality as well as to interpret the potential mechanisms. In our study, high performance liquid chromatography (HPLC) fingerprint was applied to provide a chemical profile of KT. The neonatal maternal separation (NMS) on Sprague-Dawley pups was employed to evaluate the therapeutic effect of KT by virtue of various parameters including visceral hyperalgesia, serum nitric oxide (NO) level, and tissue 5-hydroxytryptamine (5-HT) level. Consequently, a chromatographic condition, which was carried at 30°C with a flow rate of 0.5 ml/min on AQUA 3μ C18 column with mobile phase of acetonitrile and water-phosphoric acid (100:0.1, v/v), was established to give a common fingerprint chromatography under 254 nm with a similarity index of 0.963 within ten batches of KT samples. On the NMS model, KT markedly elevated the pain threshold of NMS rats. Furthermore, KT at three doses significantly decreased 5-HT content from distal colon of visceral hyperalgesia rats induced by NMS, while the significant decrease of 5-HT content in serum was only observed in the group with KT at high dose. However, compared with that in NMS rats without KT, there was no apparent difference of 5-HT level from brain issue in the rats with various doses. Besides, KT could substantially elevate the concentration of NO in the serum. The results showed our study developed the simple, rapid, accurate, reproducible qualitative and quantitative analysis by HPLC fingerprint for the quality control for KT. Data from the pharmacological investigation suggested that the curative effect of KT to the visceral hypersensitivity may be concerned with the level of 5-HT and NO in vivo, promising its potential in irritable bowel syndrome treatment.
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Affiliation(s)
- Yun-Long Chen
- School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
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Cui T, Tsolakis AV, Li SC, Cunningham JL, Lind T, Öberg K, Giandomenico V. Olfactory receptor 51E1 protein as a potential novel tissue biomarker for small intestine neuroendocrine carcinomas. Eur J Endocrinol 2013. [PMID: 23184910 DOI: 10.1530/eje-12-0814] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Late diagnosis hinders proper management of small intestine neuroendocrine carcinoma (SI-NEC) patients. The olfactory receptor, family 51, subfamily E, member 1 (OR51E1) has been reported as a potential novel SI-NEC marker, without protein expression recognition. Thus, we further studied whether the encoded protein may be a novel SI-NEC clinical biomarker. DESIGN OR51E1 coding sequence was cloned using total RNA from SI-NEC patient specimens. Quantitative real-time PCR analysis explored OR51E1 expression in laser capture microdissected SI-NEC cells and adjacent microenvironment cells. Moreover, immunohistochemistry investigated OR51E1 protein expression on operation and biopsy material from primary SI-NECs, mesentery, and liver metastases from 70 patients. Furthermore, double immunofluorescence studies explored the potential co-localization of the vesicular monoamine transporter 1 (SLC18A1, generally referred to as VMAT1) and OR51E1 in the neoplastic cells and in the intestinal mucosa adjacent to the tumor. RESULTS OR51E1 coding sequence analysis showed absence of mutation in SI-NEC patients at different stages of disease. OR51E1 expression was higher in microdissected SI-NEC cells than in the adjacent microenvironment cells. Furthermore, both membranous and cytoplasmic OR51E1 immunostaining patterns were detected in both primary SI-NECs and metastases. Briefly, 18/43 primary tumors, 7/28 mesentery metastases, and 6/18 liver metastases were 'positive' for OR51E1 in more than 50% of the tumor cells. In addition, co-localization studies showed that OR51E1 was expressed in >50% of the VMAT1 immunoreactive tumor cells and of the enterochromaffin cells in the intestinal mucosa adjacent to the tumor. CONCLUSION OR51E1 protein is a potential novel clinical tissue biomarker for SI-NECs. Moreover, we suggest its potential therapeutic molecular target development using solid tumor radioimmunotherapy.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Carcinoma, Neuroendocrine/diagnosis
- Carcinoma, Neuroendocrine/genetics
- Carcinoma, Neuroendocrine/metabolism
- Female
- Humans
- Intestinal Neoplasms/diagnosis
- Intestinal Neoplasms/genetics
- Intestinal Neoplasms/metabolism
- Intestine, Small/metabolism
- Intestine, Small/pathology
- Liver Neoplasms/genetics
- Liver Neoplasms/metabolism
- Liver Neoplasms/secondary
- Male
- Middle Aged
- Neoplasm Proteins/genetics
- Neoplasm Proteins/metabolism
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
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Affiliation(s)
- Tao Cui
- Department of Medical Sciences, Endocrine Oncology, Uppsala University, Uppsala, Sweden
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Roach G, Heath Wallace R, Cameron A, Emrah Ozel R, Hongay CF, Baral R, Andreescu S, Wallace KN. Loss of ascl1a prevents secretory cell differentiation within the zebrafish intestinal epithelium resulting in a loss of distal intestinal motility. Dev Biol 2013; 376:171-86. [PMID: 23353550 DOI: 10.1016/j.ydbio.2013.01.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 01/05/2013] [Accepted: 01/08/2013] [Indexed: 02/07/2023]
Abstract
The vertebrate intestinal epithelium is renewed continuously from stem cells at the base of the crypt in mammals or base of the fold in fish over the life of the organism. As stem cells divide, newly formed epithelial cells make an initial choice between a secretory or enterocyte fate. This choice has previously been demonstrated to involve Notch signaling as well as Atonal and Her transcription factors in both embryogenesis and adults. Here, we demonstrate that in contrast to the atoh1 in mammals, ascl1a is responsible for formation of secretory cells in zebrafish. ascl1a-/- embryos lack all intestinal epithelial secretory cells and instead differentiate into enterocytes. ascl1a-/- embryos also fail to induce intestinal epithelial expression of deltaD suggesting that ascl1a plays a role in initiation of Notch signaling. Inhibition of Notch signaling increases the number of ascl1a and deltaD expressing intestinal epithelial cells as well as the number of developing secretory cells during two specific time periods: between 30 and 34hpf and again between 64 and 74hpf. Loss of enteroendocrine products results in loss of anterograde motility in ascl1a-/- embryos. 5HT produced by enterochromaffin cells is critical in motility and secretion within the intestine. We find that addition of exogenous 5HT to ascl1a-/- embryos at near physiological levels (measured by differential pulse voltammetry) induce anterograde motility at similar levels to wild type velocity, distance, and frequency. Removal or doubling the concentration of 5HT in WT embryos does not significantly affect anterograde motility, suggesting that the loss of additional enteroendocrine products in ascl1a-/- embryos also contributes to intestinal motility. Thus, zebrafish intestinal epithelial cells appear to have a common secretory progenitor from which all subtypes form. Loss of enteroendocrine cells reveals the critical need for enteroendocrine products in maintenance of normal intestinal motility.
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Affiliation(s)
- Gillian Roach
- Department of Biology, Clarkson University, 8 Clarkson Ave., Potsdam, NY 13699, USA
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Kaji I, Akiba Y, Kaunitz JD. Digestive physiology of the pig symposium: involvement of gut chemosensing in the regulation of mucosal barrier function and defense mechanisms. J Anim Sci 2013; 91:1957-62. [PMID: 23345558 DOI: 10.2527/jas.2012-5941] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Meal ingestion is followed by release of numerous hormones from enteroendocrine cells interspersed among the epithelial cells lining the intestine. Recently, the de-orphanization of G protein-coupled receptor (GPCR)-type nutrient receptors, expressed on the apical membranes of enteroendocrine cells, has suggested a plausible mechanism whereby luminal nutrients trigger the release of gut hormones. Activation of nutrient receptors triggers intracellular signaling mechanisms that promote exocytosis of hormone-containing granules into the submucosal space. Hormones released by foregut enteroendocrine cells include the glucagon-like peptides (GLP) affecting glycemic control (GLP-1) and releasing pro-proliferative, hypertrophy-inducing growth factors (GLP-2). The foregut mucosa, being exposed to pulses of concentrated HCl, is protected by a system of defense mechanisms, which includes epithelial bicarbonate and mucus secretion and augmentation of mucosal blood flow. We have reported that luminal co-perfusion of AA with nucleotides in anesthetized rats releases GLP-2 into the portal vein, associated with increased bicarbonate and mucus secretion and mucosal blood flow. The GLP-2 increases bicarbonate secretion via release of vasoactive intestinal peptide (VIP) from myenteric nerves. Luminal bile acids also release gut hormones due to activation of the bile-acid receptor known as G Protein-Coupled Receptor (GPR) 131, G Protein Bile Acid Receptor (GPBAR) 1, or Takeda G Protein-Coupled Receptor (TGR) 5, also expressed on enteroendocrine cells. The GLP are metabolized by dipeptidyl peptidase IV (DPPIV), an enzyme of particular interest to pharmaceutical, because its inhibition increases plasma concentrations of GLP-1 to treat diabetes. We have also reported that DPPIV inhibition enhances the secretory effects of nutrient-evoked GLP-2. Understanding the release mechanism and the metabolic pathways of gut hormones is of potential utility to the formulation of feedstuff additives that, by increasing nutrient absorption due to increased mucosal mass, can increase yields.
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Affiliation(s)
- I Kaji
- Greater Los Angeles Veteran Affairs Healthcare System, WLAVA Medical Center
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125
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Besnard P. "Entero-sensory" detection of foodstuffs. Dig Dis Sci 2013. [PMID: 23196357 DOI: 10.1007/s10620-012-2491-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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126
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Alemi F, Poole DP, Chiu J, Schoonjans K, Cattaruzza F, Grider JR, Bunnett NW, Corvera CU. The receptor TGR5 mediates the prokinetic actions of intestinal bile acids and is required for normal defecation in mice. Gastroenterology 2013; 144:145-54. [PMID: 23041323 PMCID: PMC6054127 DOI: 10.1053/j.gastro.2012.09.055] [Citation(s) in RCA: 237] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 08/19/2012] [Accepted: 09/26/2012] [Indexed: 12/17/2022]
Abstract
BACKGROUND & AIMS Abnormal delivery of bile acids (BAs) to the colon as a result of disease or therapy causes constipation or diarrhea by unknown mechanisms. The G protein-coupled BA receptor TGR5 (or GPBAR1) is expressed by enteric neurons and endocrine cells, which regulate motility and secretion. METHODS We analyzed gastrointestinal and colon transit, as well as defecation frequency and water content, in wild-type, knockout, and transgenic mice (trg5-wt, tgr5-ko, and tgr5-tg, respectively). We analyzed colon tissues for contractility, peristalsis, and transmitter release. RESULTS Deoxycholic acid inhibited contractility of colonic longitudinal muscle from tgr5-wt but not tgr5-ko mice. Application of deoxycholic acid, lithocholic acid, or oleanolic acid (a selective agonist of TGR5) to the mucosa of tgr5-wt mice caused oral contraction and caudal relaxation, indicating peristalsis. BAs stimulated release of the peristaltic transmitters 5-hydroxytryptamine and calcitonin gene-related peptide; antagonists of these transmitters suppressed BA-induced peristalsis, consistent with localization of TGR5 to enterochromaffin cells and intrinsic primary afferent neurons. tgr5-ko mice did not undergo peristalsis or transmitter release in response to BAs. Mechanically induced peristalsis and transmitter release were not affected by deletion of tgr5. Whole-gut transit was 1.4-fold slower in tgr5-ko than tgr5-wt or tgr5-tg mice, whereas colonic transit was 2.2-fold faster in tgr5-tg mice. Defecation frequency was reduced 2.6-fold in tgr5-ko and increased 1.4-fold in tgr5-tg mice compared with tgr5-wt mice. Water content in stool was lower (37%) in tgr5-ko than tgr5-tg (58%) or tgr5-wt mice (62%). CONCLUSIONS The receptor TGR5 mediates the effects of BAs on colonic motility, and deficiency of TGR5 causes constipation in mice. These findings might mediate the long-known laxative properties of BAs, and TGR5 might be a therapeutic target for digestive diseases.
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Affiliation(s)
- Farzad Alemi
- Department of Surgery, University of California, San Francisco,513 Parnassus Avenue, San Francisco, CA 94143, USA
| | - Daniel P. Poole
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, VIC 3010, Australia
| | - Jonathan Chiu
- Department of Surgery, University of California, San Francisco,513 Parnassus Avenue, San Francisco, CA 94143, USA
| | - Kristina Schoonjans
- Laboratory of Integrative and Systems Physiology, Institute of Bioengineering, School of Life Sciences, EPFL, SV, Station 15, CH-1015 Lausanne, Switzerland
| | - Fiore Cattaruzza
- Department of Surgery, University of California, San Francisco,513 Parnassus Avenue, San Francisco, CA 94143, USA
| | - John R. Grider
- Department of Physiology, P.O. Box 980551 Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Nigel W. Bunnett
- Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville,VIC 3052, Australia
| | - Carlos U. Corvera
- Department of Surgery, University of California, San Francisco,513 Parnassus Avenue, San Francisco, CA 94143, USA
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Haugen M, Dammen R, Svejda B, Gustafsson BI, Pfragner R, Modlin I, Kidd M. Differential signal pathway activation and 5-HT function: the role of gut enterochromaffin cells as oxygen sensors. Am J Physiol Gastrointest Liver Physiol 2012; 303:G1164-73. [PMID: 22936271 PMCID: PMC3517648 DOI: 10.1152/ajpgi.00027.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The chemomechanosensory function of the gut enterochromaffin (EC) cell enables it to respond to dietary agents and mechanical stretch. We hypothesized that the EC cell, which also sensed alterations in luminal or mucosal oxygen level, was physiologically sensitive to fluctuations in O(2). Given that low oxygen levels induce 5-HT production and secretion through a hypoxia inducible factor 1α (HIF-1α)-dependent pathway, we also hypothesized that increasing O(2) would reduce 5-HT production and secretion. Isolated normal EC cells as well as the well-characterized EC cell model KRJ-I were used to examine HIF signaling (luciferase-assays), hypoxia transcriptional response element (HRE)-mediated transcription (PCR), signaling pathways (Western blot), and 5-HT release (ELISA) during exposure to different oxygen levels. Normal EC cells and KRJ-I cells express HIF-1α, and transient transfection with Renilla luciferase under HRE control identified a hypoxia-mediated pathway in these cells. PCR confirmed activation of HIF-downstream targets, GLUT1, IGF2, and VEGF under reduced O(2) levels (0.5%). Reducing O(2) also elevated 5-HT secretion (2-3.2-fold) as well as protein levels of HIF-1α (1.7-3-fold). Increasing O(2) to 100% inhibited HRE-mediated signaling, transcription, reduced 5-HT secretion, and significantly lowered HIF-1α levels (∼75% of control). NF-κB signaling was also elevated during hypoxia (1.2-1.6-fold), but no significant changes were noted in PKA/cAMP. We concluded that gut EC cells are oxygen responsive, and alterations in O(2) levels differentially activate HIF-1α and tryptophan hydroxylase 1, as well as NF-κB signaling. This results in alterations in 5-HT production and secretion and identifies that the chemomechanosensory role of EC cells extends to oxygen sensing.
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Affiliation(s)
- Martin Haugen
- 1Gastrointestinal Pathobiology Research Group, Yale University School of Medicine, New Haven, Connecticut;
| | - Rikard Dammen
- 1Gastrointestinal Pathobiology Research Group, Yale University School of Medicine, New Haven, Connecticut;
| | - Bernhard Svejda
- 1Gastrointestinal Pathobiology Research Group, Yale University School of Medicine, New Haven, Connecticut;
| | - Bjorn I. Gustafsson
- 2Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway;
| | - Roswitha Pfragner
- 3Institute of Pathophysiology and Immunology, Centre for Molecular Medicine, Graz, Austria
| | - Irvin Modlin
- 1Gastrointestinal Pathobiology Research Group, Yale University School of Medicine, New Haven, Connecticut;
| | - Mark Kidd
- 1Gastrointestinal Pathobiology Research Group, Yale University School of Medicine, New Haven, Connecticut;
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128
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Pakladok T, Hosseinzadeh Z, Alesutan I, Lang F. Stimulation of the Na+-coupled glucose transporter SGLT1 by B-RAF. Biochem Biophys Res Commun 2012; 427:689-93. [DOI: 10.1016/j.bbrc.2012.09.062] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 09/08/2012] [Indexed: 12/27/2022]
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129
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Affiliation(s)
- Michael Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), College of Medicine, Mayo Clinic, Rochester, MN 55905, USA.
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130
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Badiali L, Cedernaes J, Olszewski PK, Nylander O, Vergoni AV, Schiöth HB. Adhesion GPCRs are widely expressed throughout the subsections of the gastrointestinal tract. BMC Gastroenterol 2012; 12:134. [PMID: 23009096 PMCID: PMC3526421 DOI: 10.1186/1471-230x-12-134] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 08/31/2012] [Indexed: 12/22/2022] Open
Abstract
Background G protein-coupled receptors (GPCRs) represent one of the largest families of transmembrane receptors and the most common drug target. The Adhesion subfamily is the second largest one of GPCRs and its several members are known to mediate neural development and immune system functioning through cell-cell and cell-matrix interactions. The distribution of these receptors has not been characterized in detail in the gastrointestinal (GI) tract. Here we present the first comprehensive anatomical profiling of mRNA expression of all 30 Adhesion GPCRs in the rat GI tract divided into twelve subsegments. Methods Using RT-qPCR, we studied the expression of Adhesion GPCRs in the esophagus, the corpus and antrum of the stomach, the proximal and distal parts of the duodenum, ileum, jejunum and colon, and the cecum. Results We found that twenty-one Adhesion GPCRs (70%) had a widespread (expressed in five or more segments) or ubiquitous (expressed in eleven or more segments) distribution, seven (23%) were restricted to a few segments of the GI tract and two were not expressed in any segment. Most notably, almost all Group III members were ubiquitously expressed, while the restricted expression was characteristic for the majority of group VII members, hinting at more specific/localized roles for some of these receptors. Conclusions Overall, the distribution of Adhesion GPCRs points to their important role in GI tract functioning and defines them as a potentially crucial target for pharmacological interventions.
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Affiliation(s)
- Luca Badiali
- Department of Neuroscience, Uppsala University, BMC, Uppsala, SE 75124, Sweden
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131
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Launay G, Sanz G, Pajot-Augy E, Gibrat JF. Modeling of mammalian olfactory receptors and docking of odorants. Biophys Rev 2012; 4:255-269. [PMID: 28510073 DOI: 10.1007/s12551-012-0080-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2012] [Accepted: 05/24/2012] [Indexed: 11/29/2022] Open
Abstract
Olfactory receptors (ORs) belong to the superfamily of G protein-coupled receptors (GPCRs), the second largest class of genes after those related to immunity, and account for about 3 % of mammalian genomes. ORs are present in all multicellular organisms and represent more than half the GPCRs in mammalian species (e.g., the mouse OR repertoire contains >1,000 functional genes). ORs are mainly expressed in the olfactory epithelium where they detect odorant molecules, but they are also expressed in a number of other cells, such as sperm cells, although their functions in these cells remain mostly unknown. It has recently been reported that ORs are present in tumoral tissues where they are expressed at different levels than in healthy tissues. A specific OR is over-expressed in prostate cancer cells, and activation of this OR has been shown to inhibit the proliferation of these cells. Odorant stimulation of some of these receptors results in inhibition of cell proliferation. Even though their biological role has not yet been elucidated, these receptors might constitute new targets for diagnosis and therapeutics. It is important to understand the activation mechanism of these receptors at the molecular level, in particular to be able to predict which ligands are likely to activate a particular receptor ('deorphanization') or to design antagonists for a given receptor. In this review, we describe the in silico methodologies used to model the three-dimensional (3D) structure of ORs (in the more general framework of GPCR modeling) and to dock ligands into these 3D structures.
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Affiliation(s)
- Guillaume Launay
- Equipe interactions hôte-pathogène, Bases Moléculaires et Structurales des Systèmes Infectieux, UMR5086 CNRS/Université de Lyon1, 7 Passage du Vercors, Lyon cedex 07, France
| | - Guenhaël Sanz
- Neurobiologie de l'Olfaction et Modélisation en Imagerie UR1197, INRA, 78350, Jouy-en-Josas, France
| | - Edith Pajot-Augy
- Neurobiologie de l'Olfaction et Modélisation en Imagerie UR1197, INRA, 78350, Jouy-en-Josas, France
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132
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Thomson ABR, Chopra A, Clandinin MT, Freeman H. Recent advances in small bowel diseases: Part I. World J Gastroenterol 2012; 18:3336-52. [PMID: 22807604 PMCID: PMC3396187 DOI: 10.3748/wjg.v18.i26.3336] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 04/05/2012] [Accepted: 04/13/2012] [Indexed: 02/06/2023] Open
Abstract
As is the case in all parts of gastroenterology and hepatology, there have been many advances in our knowledge and understanding of small intestinal diseases. Over 1000 publications were reviewed for 2008 and 2009, and the important advances in basic science as well as clinical applications were considered. In Part I of this Editorial Review, seven topics are considered: intestinal development; proliferation and repair; intestinal permeability; microbiotica, infectious diarrhea and probiotics; diarrhea; salt and water absorption; necrotizing enterocolitis; and immunology/allergy. These topics were chosen because of their importance to the practicing physician.
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133
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Insel PA, Snead A, Murray F, Zhang L, Yokouchi H, Katakia T, Kwon O, Dimucci D, Wilderman A. GPCR expression in tissues and cells: are the optimal receptors being used as drug targets? Br J Pharmacol 2012; 165:1613-1616. [PMID: 21488863 DOI: 10.1111/j.1476-5381.2011.01434.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
G-protein-coupled receptors [GPCRs, also known as 7-transmembrane (7-TM) receptors] comprise the largest family of membrane receptors in humans and other species and, in addition, represent the greatest number of current drug targets. In this article, we review methods to define GPCR expression and data indicating that individual cells express >100 different GPCRs. Results from studies that have quantified expression of these receptors lead us to conclude that the optimal GPCRs may not be currently used as therapeutic targets. We propose that studies of GPCR expression in individual cells will likely reveal new insights regarding cellular physiology and therapeutic approaches. Findings that define and characterize the most highly expressed GPCRs thus have important potential in terms of identifying new drug targets and novel therapies directed at a wide range of clinical disorders.
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Affiliation(s)
- P A Insel
- Departments of PharmacologyMedicine, University of California, San Diego, La Jolla, CA, USA
| | - A Snead
- Departments of PharmacologyMedicine, University of California, San Diego, La Jolla, CA, USA
| | - F Murray
- Departments of PharmacologyMedicine, University of California, San Diego, La Jolla, CA, USA
| | - L Zhang
- Departments of PharmacologyMedicine, University of California, San Diego, La Jolla, CA, USA
| | - H Yokouchi
- Departments of PharmacologyMedicine, University of California, San Diego, La Jolla, CA, USA
| | - T Katakia
- Departments of PharmacologyMedicine, University of California, San Diego, La Jolla, CA, USA
| | - O Kwon
- Departments of PharmacologyMedicine, University of California, San Diego, La Jolla, CA, USA
| | - D Dimucci
- Departments of PharmacologyMedicine, University of California, San Diego, La Jolla, CA, USA
| | - A Wilderman
- Departments of PharmacologyMedicine, University of California, San Diego, La Jolla, CA, USA
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134
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Rokstad AM, Gustafsson BI, Espevik T, Bakke I, Pfragner R, Svejda B, Modlin IM, Kidd M. Microencapsulation of small intestinal neuroendocrine neoplasm cells for tumor model studies. Cancer Sci 2012; 103:1230-7. [PMID: 22435758 DOI: 10.1111/j.1349-7006.2012.02282.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 03/07/2012] [Accepted: 03/09/2012] [Indexed: 01/26/2023] Open
Abstract
Basic cancer research is dependent on reliable in vitro and in vivo tumor models. The serotonin (5-HT) producing small intestinal neuroendocrine tumor cell line KRJ-1 has been used in in vitro proliferation and secretion studies, but its use in in vivo models has been hampered by problems related to the xeno-barrier and tumor formation. This may be overcome by the encapsulation of tumor cells into alginate microspheres, which can function as bioreactors and protect against the host immune system. We used alginate encapsulation of KRJ-1 cells to achieve long-term functionality, growth and survival. Different conditions, including capsule size, variations in M/G content, gelling ions (Ca(2+) /Ba(2+)) and microcapsule core properties, and variations in KRJ-1 cell condition (single cells/spheroids) were tested. Viability and cell growth was evaluated with MTT, and confocal laser scanner microscopy combined with LIVE/DEAD viability stains. 5-HT secretion was measured to determine functionality. Under all conditions, single cell encapsulation proved unfavorable due to gradual cell death, while encapsulation of aggregates/spheroids resulted in surviving, functional bioreactors. The most ideal spheroids for encapsulation were 200-350 μm. Long-term survival (>30 days) was seen with solid Ca(2+) /Ba(2+) microbeads and hollow microcapsules. Basal 5-HT secretion was increased (sixfold) after hollow microcapsule encapsulation, while Ca(2+) /Ba(2+) microbeads was associated with normal basal secretion and responsiveness to cAMP/PKA activation. In conclusion, encapsulation of KRJ-1 cells into hollow microcapsules produces a bioreactor with a high constitutively activate basal 5-HT secretion, while Ca(2+) /Ba(2+) microbeads provide a more stable bioreactor similar to non-encapsulated cells. Alginate microspheres technology can thus be used to tailor different functional bioreactors for both in vitro and in vivo studies.
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Affiliation(s)
- Anne M Rokstad
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
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135
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Gastrointestinal chemosensation: chemosensory cells in the alimentary tract. Histochem Cell Biol 2012; 138:13-24. [DOI: 10.1007/s00418-012-0954-z] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/01/2012] [Indexed: 12/29/2022]
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136
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Reimann F, Tolhurst G, Gribble FM. G-protein-coupled receptors in intestinal chemosensation. Cell Metab 2012; 15:421-31. [PMID: 22482725 DOI: 10.1016/j.cmet.2011.12.019] [Citation(s) in RCA: 174] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 11/21/2011] [Accepted: 12/15/2011] [Indexed: 12/25/2022]
Abstract
Food intake is detected by the chemical senses of taste and smell and subsequently by chemosensory cells in the gastrointestinal tract that link the composition of ingested foods to feedback circuits controlling gut motility/secretion, appetite, and peripheral nutrient disposal. G-protein-coupled receptors responsive to a range of nutrients and other food components have been identified, and many are localized to intestinal chemosensory cells, eliciting hormonal and neuronal signaling to the brain and periphery. This review examines the role of G-protein-coupled receptors as signaling molecules in the gut, with a particular focus on pathways relevant to appetite and glucose homeostasis.
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Affiliation(s)
- Frank Reimann
- Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge, UK.
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137
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Walker J, Hell J, Liszt KI, Dresel M, Pignitter M, Hofmann T, Somoza V. Identification of beer bitter acids regulating mechanisms of gastric acid secretion. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:1405-1412. [PMID: 22313115 DOI: 10.1021/jf204306z] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Beer, one of the most consumed beverages worldwide, has been shown to stimulate gastric acid secretion. Although organic acids, formed by fermentation of glucose, are known to be stimulants of gastric acid secretion, very little is known about the effects of different types of beer or the active constituents thereof. In the present study, we compared the effects of different beers on mechanisms of gastric acid secretion. To investigate compound-specific effects on mechanisms of gastric acid secretion, organic acids and bitter compounds were quantified by HPLC-DAD and UPLC-MS/MS and tested in human gastric cancer cells (HGT-1) by means of a pH-sensitive fluorescent dye which determines the intracellular pH as an indicator of proton secretion. The expression of relevant genes, coding the H(+)/K(+)-ATPase, ATP4A, the histamine receptor, HRH2, the acetylcholine receptor, CHRM3, and the somatostatin receptor, SSTR2, was determined by qPCR. Ethanol and the organic acids succinic acid, malic acid, and citric acid were demonstrated to contribute to some extent to the effect of beer. The bitter acids comprising α-, β-, and iso-α-acids were identified as potential key components promoting gastric acid secretion and up-regulation of CHRM3 gene expression by a maximum factor of 2.01 compared to that of untreated control cells with a correlation to their respective bitterness.
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Affiliation(s)
- Jessica Walker
- Department of Nutritional and Physiological Chemistry, University of Vienna, Althanstrasse 14 (UZA II), A-1090 Vienna, Austria
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138
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Chin A, Svejda B, Gustafsson BI, Granlund AB, Sandvik AK, Timberlake A, Sumpio B, Pfragner R, Modlin IM, Kidd M. The role of mechanical forces and adenosine in the regulation of intestinal enterochromaffin cell serotonin secretion. Am J Physiol Gastrointest Liver Physiol 2012; 302:G397-405. [PMID: 22038827 PMCID: PMC3287403 DOI: 10.1152/ajpgi.00087.2011] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Enterochromaffin (EC) cells of the diffuse neuroendocrine cell system secrete serotonin (5-HT) with activation of gut motility, secretion, and pain. These cells express adenosine (ADORA) receptors and are considered to function as mechanosensors. Physiological pathways mediating mechanosensitivity and adenosine responsiveness remain to be fully elucidated, as do their roles in inflammatory bowel disease (IBD) and neoplasia. Pure (98-99%) FACS-sorted normal and IBD human EC cells and neoplastic EC cells (KRJ-I) were studied. IBD-EC cells and KRJ-I overexpressed ADORA2B. NECA, a general ADORA receptor agonist, stimulated, whereas the A2B receptor antagonist MRS1754 inhibited, 5-HT release (EC50 = 1.8 × 10-6 M; IC50 = 3.7 × 10-8 M), which was associated with corresponding alterations in intracellular cAMP levels and pCREB (Ser133). Mechanical stimulation using a rhythmic flex model induced transcription and activation of Tph1 (tryptophan hydroxylase) and VMAT₁ (vesicular monoamine transporter 1) and the release of 5-HT, which could be inhibited by MRS1754 and amplified by NECA. Secretion was also inhibited by H-89 (PKA inhibitor) while Tph1 and VMAT₁ transcription was regulated by PKA/MAPK and PI₃K-mediated signaling. Normal and IBD-EC cells also responded to NECA and mechanical stimulation with PKA activation, cAMP production, and 5-HT release, effects reversible by MRS1754. EC cells express stimulatory ADORA2B, and rhythmic stretch induces A2B activation, PKA/MAPK/IP3-dependent transcription, and PKA-dependent secretion of 5-HT synthesis and secretion. Receptor expression is amplified in IBD and neoplasia, and 5-HT release is increased. Determination of factors that regulate EC cell function are necessary for understanding its role as a mechanosensory cell and to facilitate the development of agents that can selectively target cell function in EC cell-associated disease.
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Affiliation(s)
- A. Chin
- 1Gastrointestinal Surgery, and
| | | | - B. I. Gustafsson
- 3Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim; ,4Department of Gastroenterology, St. Olav's University Hospital, Trondheim, Norway; and
| | - A. B. Granlund
- 3Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim;
| | - A. K. Sandvik
- 3Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim; ,4Department of Gastroenterology, St. Olav's University Hospital, Trondheim, Norway; and
| | | | - B. Sumpio
- 2Vascular Surgery, Yale University School of Medicine, New Haven, Connecticut;
| | - R. Pfragner
- 5Institute of Pathophysiology and Immunology, Center for Molecular Medicine, Medical University of Graz, Graz, Austria
| | | | - M. Kidd
- 1Gastrointestinal Surgery, and
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139
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KAJI I, KARAKI SI, KUWAHARA A. Chemosense for Luminal Environment in the Large Intestine. YAKUGAKU ZASSHI 2011; 131:1691-8. [DOI: 10.1248/yakushi.131.1691] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Izumi KAJI
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences/Institute for Environmental Sciences, University of Shizuoka
| | - Shin-ichiro KARAKI
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences/Institute for Environmental Sciences, University of Shizuoka
| | - Atsukazu KUWAHARA
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences/Institute for Environmental Sciences, University of Shizuoka
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140
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Karsenty G, Gershon MD. The importance of the gastrointestinal tract in the control of bone mass accrual. Gastroenterology 2011; 141:439-42. [PMID: 21699800 PMCID: PMC4902797 DOI: 10.1053/j.gastro.2011.06.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
One of the least anticipated and less heralded outcomes of mouse genetics has been to rediscover whole organism physiology. Among the many unexpected findings that it has brought to our attention has been the realization that gut-derived serotonin is a hormone-inhibiting bone formation. The importance of this discovery presented in this review is 2-fold. First, it provides a molecular explanation for 2 human genetic diseases-osteoporosis, pseudoglioma, and high bone mass syndrome; second, it suggests a novel and anabolic way to treat osteoporosis. These findings illustrate the importance of the gastrointestinal tract in the regulation of organ physiology at yet another extraluminal site.
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Affiliation(s)
- Gerard Karsenty
- Department of Genetics and Development, Columbia University, New York, New York, USA.
| | - Michael D. Gershon
- Department of Pathology and Cell Biology, Columbia University, New York, New York
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141
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Mourad FH, Saadé NE. Neural regulation of intestinal nutrient absorption. Prog Neurobiol 2011; 95:149-62. [PMID: 21854830 DOI: 10.1016/j.pneurobio.2011.07.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Revised: 04/28/2011] [Accepted: 07/20/2011] [Indexed: 12/17/2022]
Abstract
The nervous system and the gastrointestinal (GI) tract share several common features including reciprocal interconnections and several neurotransmitters and peptides known as gut peptides, neuropeptides or hormones. The processes of digestion, secretion of digestive enzymes and then absorption are regulated by the neuro-endocrine system. Luminal glucose enhances its own absorption through a neuronal reflex that involves capsaicin sensitive primary afferent (CSPA) fibres. Absorbed glucose stimulates insulin release that activates hepatoenteric neural pathways leading to an increase in the expression of glucose transporters. Adrenergic innervation increases glucose absorption through α1 and β receptors and decreases absorption through activation of α2 receptors. The vagus nerve plays an important role in the regulation of diurnal variation in transporter expression and in anticipation to food intake. Vagal CSPAs exert tonic inhibitory effects on amino acid absorption. It also plays an important role in the mediation of the inhibitory effect of intestinal amino acids on their own absorption at the level of proximal or distal segment. However, chronic extrinsic denervation leads to a decrease in intestinal amino acid absorption. Conversely, adrenergic agonists as well as activation of CSPA fibres enhance peptides uptake through the peptide transporter PEPT1. Finally, intestinal innervation plays a minimal role in the absorption of fat digestion products. Intestinal absorption of nutrients is a basic vital mechanism that depends essentially on the function of intestinal mucosa. However, intrinsic and extrinsic neural mechanisms that rely on several redundant loops are involved in immediate and long-term control of the outcome of intestinal function.
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Affiliation(s)
- Fadi H Mourad
- Department of Internal Medicine, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.
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142
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Hagbom M, Istrate C, Engblom D, Karlsson T, Rodriguez-Diaz J, Buesa J, Taylor JA, Loitto VM, Magnusson KE, Ahlman H, Lundgren O, Svensson L. Rotavirus stimulates release of serotonin (5-HT) from human enterochromaffin cells and activates brain structures involved in nausea and vomiting. PLoS Pathog 2011; 7:e1002115. [PMID: 21779163 PMCID: PMC3136449 DOI: 10.1371/journal.ppat.1002115] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Accepted: 04/26/2011] [Indexed: 11/18/2022] Open
Abstract
Rotavirus (RV) is the major cause of severe gastroenteritis in young children. A virus-encoded enterotoxin, NSP4 is proposed to play a major role in causing RV diarrhoea but how RV can induce emesis, a hallmark of the illness, remains unresolved. In this study we have addressed the hypothesis that RV-induced secretion of serotonin (5-hydroxytryptamine, 5-HT) by enterochromaffin (EC) cells plays a key role in the emetic reflex during RV infection resulting in activation of vagal afferent nerves connected to nucleus of the solitary tract (NTS) and area postrema in the brain stem, structures associated with nausea and vomiting. Our experiments revealed that RV can infect and replicate in human EC tumor cells ex vivo and in vitro and are localized to both EC cells and infected enterocytes in the close vicinity of EC cells in the jejunum of infected mice. Purified NSP4, but not purified virus particles, evoked release of 5-HT within 60 minutes and increased the intracellular Ca2+ concentration in a human midgut carcinoid EC cell line (GOT1) and ex vivo in human primary carcinoid EC cells concomitant with the release of 5-HT. Furthermore, NSP4 stimulated a modest production of inositol 1,4,5-triphosphate (IP3), but not of cAMP. RV infection in mice induced Fos expression in the NTS, as seen in animals which vomit after administration of chemotherapeutic drugs. The demonstration that RV can stimulate EC cells leads us to propose that RV disease includes participation of 5-HT, EC cells, the enteric nervous system and activation of vagal afferent nerves to brain structures associated with nausea and vomiting. This hypothesis is supported by treating vomiting in children with acute gastroenteritis with 5-HT3 receptor antagonists. Rotavirus (RV) can cause severe dehydration and is a leading cause of childhood deaths worldwide. While most deaths occur due to excessive loss of fluids and electrolytes through vomiting and diarrhoea, the pathophysiological mechanisms that underlie this life-threatening disease remain to be clarified. Our previous studies revealed that drugs that inhibit the function of the enteric nervous system can reduce symptoms of RV disease in mice. In this study we have addressed the hypothesis that RV infection triggers the release of serotonin (5-hydroxytryptamine, 5-HT) from enterochromaffin (EC) cells in the intestine leading to activation of vagal afferent nerves connected to brain stem structures associated with vomiting. RV activated Fos expression in the nucleus of the solitary tract of CNS, the main target for incoming fibers from the vagal nerve. Both secreted and recombinant forms of the viral enterotoxin (NSP4), increased intracellular Ca2+ concentration and released 5-HT from EC cells. 5-HT induced diarrhoea in mice within 60 min, thereby supporting the role of 5-HT in RV disease. Our study provides novel insight into the complex interaction between RV, EC cells, 5-HT and nerves.
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Affiliation(s)
- Marie Hagbom
- Division of Molecular Virology, Medical Faculty, University of Linköping, Linköping, Sweden
| | - Claudia Istrate
- Division of Molecular Virology, Medical Faculty, University of Linköping, Linköping, Sweden
- Unidade de Biologia Molecular, Centro de Malaria e Outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisboa, Portugal
| | - David Engblom
- Division of Cell Biology, Medical Faculty, University of Linköping, Linköping, Sweden
| | - Thommie Karlsson
- Division of Medical Microbiology, Medical Faculty, University of Linköping, Linköping, Sweden
| | - Jesus Rodriguez-Diaz
- Department of Microbiology, School of Medicine, University of Valencia, Valencia, Spain
| | - Javier Buesa
- Department of Microbiology, School of Medicine, University of Valencia, Valencia, Spain
| | - John A. Taylor
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Vesa-Matti Loitto
- Division of Medical Microbiology, Medical Faculty, University of Linköping, Linköping, Sweden
| | - Karl-Eric Magnusson
- Division of Medical Microbiology, Medical Faculty, University of Linköping, Linköping, Sweden
| | - Håkan Ahlman
- Department of Surgery, University of Gothenburg, Gothenburg, Sweden
| | - Ove Lundgren
- Department of Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Lennart Svensson
- Division of Molecular Virology, Medical Faculty, University of Linköping, Linköping, Sweden
- * E-mail:
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143
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Kaji I, Karaki SI, Kuwahara A. Effects of luminal thymol on epithelial transport in human and rat colon. Am J Physiol Gastrointest Liver Physiol 2011; 300:G1132-43. [PMID: 21372164 DOI: 10.1152/ajpgi.00503.2010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Gut lumen is continually exposed to a great variety of agents, including noxious compounds. Chemical receptors that detect the luminal environment are thought to play an important role as sensors and to modulate gastrointestinal functions. Recently, it has been reported that odorant receptors (ORs) are expressed in the small intestinal mucosa and that odorants stimulate serotonin secretion. However, ion transport in the responses to odorants has rarely been discussed, particularly in relation to the large intestine. In the present study, we examined the effects of the OR ligand thymol on ion transport in human and rat colonic epithelia using an Ussing chamber. In the mucosal-submucosal preparations, the mucosal addition of thymol evoked anion secretion concentration dependently. In addition, dextran (4 kDa) permeability was enhanced by the mucosal treatment with thymol. The response to thymol was not affected by tetrodotoxin (TTX) or piroxicam treatments in human or rat colon. Thymol-evoked electrogenic anion secretion was abolished under Ca(2+)-free conditions or mucosal treatment with transient receptor potential (TRP) A1 blocker (HC-030031). Pretreatment of thymol did not affect electrical field stimulation-evoked anion secretion but significantly attenuated short-chain fatty acid-evoked secretion in a concentration-dependent manner. OR1G1 and TRPA1 expression was investigated in isolated colonic mucosa by RT-PCR. The present results provide evidence that the OR ligand thymol modulates epithelial permeability and electrogenic anion secretion in human and rat colon. The anion secretion by luminal thymol is most likely mediated by direct activation of TRPA1 channel. We suggest that the sensing and responding to odorants in the colon also plays a role in maintaining intestinal homeostasis.
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Affiliation(s)
- Izumi Kaji
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences, Institute of Environmental Sciences, University of Shizuoka, Japan
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144
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Abstract
PURPOSE OF REVIEW Two independent serotonin systems exist, one in the brain and the other in the periphery. Serotonin is a well known monoaminergic neurotransmitter in the central nervous system and it is known to regulate feeding behavior, meal size, and body weight. On the other hand, there is much less evidence for the role of serotonin as a gastrointestinal hormone, particularly with respect to its effects on glucose and lipid metabolism. This review summarizes our current understanding of the role of peripheral serotonin on glucose and lipid metabolism and the implications of this for further research. RECENT FINDINGS The enterochromaffin cells of the gastrointestinal tract produce peripheral serotonin postprandially. In mice, it induces a decrease in the concentration of circulating lipids as well as hyperglycemia and hyperinsulinemia through its action on several serotonin receptors. Further, serotonin metabolites act as endogenous agonists for peroxisome proliferator-activated receptor γ and serotonin accelerates adipocyte differentiation via serotonin receptor 2A and 2C. Studies of serotonin are likely to provide new insights into the field of lipid accumulation and metabolism. SUMMARY Recent studies show new physiological functions of peripheral serotonin, linked to glucose and lipid metabolism. Peripheral serotonin may serve as an attractive new therapeutic target for the treatment of metabolic disorders in the near future.
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Affiliation(s)
- Hitoshi Watanabe
- Cellular Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
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145
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Hosseinzadeh Z, Bhavsar SK, Shojaiefard M, Saxena A, Merches K, Sopjani M, Alesutan I, Lang F. Stimulation of the glucose carrier SGLT1 by JAK2. Biochem Biophys Res Commun 2011; 408:208-13. [DOI: 10.1016/j.bbrc.2011.03.036] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 03/08/2011] [Indexed: 12/17/2022]
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146
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Gunawardene AR, Corfe BM, Staton CA. Classification and functions of enteroendocrine cells of the lower gastrointestinal tract. Int J Exp Pathol 2011; 92:219-31. [PMID: 21518048 DOI: 10.1111/j.1365-2613.2011.00767.x] [Citation(s) in RCA: 183] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
With over thirty different hormones identified as being produced in the gastrointestinal (GI) tract, the gut has been described as 'the largest endocrine organ in the body' (Ann. Oncol., 12, 2003, S63). The classification of these hormones and the cells that produce them, the enteroendocrine cells (EECs), has provided the foundation for digestive physiology. Furthermore, alterations in the composition and function of EEC may influence digestive physiology and thereby associate with GI pathologies. Whilst there is a rapidly increasing body of data on the role and function of EEC in the upper GI tract, there is a less clear-cut understanding of the function of EEC in the lower GI. Nonetheless, their presence and diversity are indicative of a role. This review focuses on the EECs of the lower GI where new evidence also suggests a possible relationship with the development and progression of primary adenocarcinoma.
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Affiliation(s)
- Ashok R Gunawardene
- Department of Oncology, The Medical School, University of Sheffield, Sheffield, UK
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147
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Tumor suppressor gene adenomatous polyposis coli downregulates intestinal transport. Pflugers Arch 2011; 461:527-36. [DOI: 10.1007/s00424-011-0945-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 02/15/2011] [Accepted: 02/16/2011] [Indexed: 12/21/2022]
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148
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Spiller RC. Targeting the 5-HT(3) receptor in the treatment of irritable bowel syndrome. Curr Opin Pharmacol 2011; 11:68-74. [PMID: 21398180 DOI: 10.1016/j.coph.2011.02.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Revised: 02/13/2011] [Accepted: 02/14/2011] [Indexed: 12/18/2022]
Abstract
Irritable bowel syndrome, which affects 5-10% of the population includes around 25% with predominantly diarrhoea (IBS-D). Several lines of evidence suggest an increase in mucosal 5-HT availability in IBS-D including a decrease in the serotonin transporter (SERT) which is also seen following acute diverticulitis. 5-HT(3) receptor antagonists have proved effective in suppressing urgency, prolonging small and large bowel transit and relieving symptoms in IBS-D. Alosetron continues to be used under restricted availability without any serious morbidity despite ischemic colitis which occurs at a rate of <1/1000 patient year. Other agents such as ramosetron and ondansetron are still in use and have not been associated with ischemic colitis. 5-HT(3) receptor agonists stimulate intestinal motility, shorten transit times and in a pilot trial accelerated transit in patients with IBS-C.
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Affiliation(s)
- Robin C Spiller
- NIHR Biomedical Research Unit, Nottingham Digestive Diseases Centre, University Hospital, Nottingham NG7 2UH, United Kingdom.
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149
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Young RL. Sensing via intestinal sweet taste pathways. Front Neurosci 2011; 5:23. [PMID: 21519398 PMCID: PMC3080736 DOI: 10.3389/fnins.2011.00023] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2010] [Accepted: 02/10/2011] [Indexed: 12/15/2022] Open
Abstract
The detection of nutrients in the gastrointestinal (GI) tract is of fundamental significance to the control of motility, glycemia and energy intake, and yet we barely know the most fundamental aspects of this process. This is in stark contrast to the mechanisms underlying the detection of lingual taste, which have been increasingly well characterized in recent years, and which provide an excellent starting point for characterizing nutrient detection in the intestine. This review focuses on the form and function of sweet taste transduction mechanisms identified in the intestinal tract; it does not focus on sensors for fatty acids or proteins. It examines the intestinal cell types equipped with sweet taste transduction molecules in animals and humans, their location, and potential signals that transduce the presence of nutrients to neural pathways involved in reflex control of GI motility.
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Affiliation(s)
- Richard L Young
- Discipline of Medicine, School of Medicine, University of Adelaide Adelaide, SA, Australia
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150
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Schimmack S, Svejda B, Lawrence B, Kidd M, Modlin IM. The diversity and commonalities of gastroenteropancreatic neuroendocrine tumors. Langenbecks Arch Surg 2011; 396:273-98. [DOI: 10.1007/s00423-011-0739-1] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 01/07/2011] [Indexed: 02/07/2023]
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