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Annaházi A, Berger TE, Demir IE, Zeller F, Müller M, Anneser M, Skerra A, Michel K, Schemann M. Metabotropic 5-HT receptor-mediated effects in the human submucous plexus. Neurogastroenterol Motil 2022; 34:e14380. [PMID: 35438222 DOI: 10.1111/nmo.14380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 03/04/2022] [Accepted: 03/28/2022] [Indexed: 12/16/2022]
Abstract
BACKGROUND Serotonin (5-HT) is an important mediator in the gastrointestinal tract, acting on different neuronal 5-HT receptors. The ionotropic 5-HT3 receptor mediates immediate but transient spike discharge in human enteric neurons. We studied the role of the metabotropic 5-HT1P , 5-HT4 , and 5-HT7 receptors to activate human submucous neurons. METHODS Neuroimaging using the voltage sensitive dye Di-8-ANEPPS was performed in submucous plexus preparations from human surgical specimens of the small and large intestine. We synthesized a new, stable 5-HT1P agonist, 5-benzyloxyhydrazonoindalpine (5-BOHIP). KEY RESULTS 5-HT evoked a fast and late-onset spike discharge in enteric neurons. The fast component was blocked by the 5-HT3 receptor antagonist cilansetron, while the remaining sustained response was significantly reduced by the 5-HT1P receptor antagonist 5-hydroxytryptophanyl-5-hydroxytryptophan amide (5-HTP-DP). The newly synthesized 5-HT1P agonist 5-BOHIP induced a slowly developing, long-lasting activation of submucous neurons, which was blocked by 5-HTP-DP. We could not demonstrate any 5-HT7 receptor-induced spike discharge based on the lack of response to 5-carboxamidotryptamine. Similarly, the 5-HT4 agonists 5-methoxytryptamine and prucalopride evoked no immediate or late-onset spike discharge. CONCLUSIONS & INFERENCES Our work demonstrated for the first time the presence of functional 5-HT1P receptors on human submucous neurons. Furthermore, we found no evidence for a role of 5-HT4 or 5-HT7 receptors in the postsynaptic activation of human submucous neurons by 5-HT.
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Affiliation(s)
- Anita Annaházi
- Chair of Human Biology, Technical University of Munich, Freising, Germany
| | | | - Ihsan Ekin Demir
- Department of Surgery, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
| | - Florian Zeller
- Department of Surgery, Klinikum Freising, Freising, Germany
| | - Michael Müller
- Chair of Biological Chemistry, Technical University of Munich, Freising, Germany
| | - Markus Anneser
- Chair of Biological Chemistry, Technical University of Munich, Freising, Germany
| | - Arne Skerra
- Chair of Biological Chemistry, Technical University of Munich, Freising, Germany
| | - Klaus Michel
- Chair of Human Biology, Technical University of Munich, Freising, Germany
| | - Michael Schemann
- Chair of Human Biology, Technical University of Munich, Freising, Germany
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2
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Gwynne RM, Bornstein JC. Luminal 5-HT 4 receptors-A successful target for prokinetic actions. Neurogastroenterol Motil 2019; 31:e13708. [PMID: 31524331 DOI: 10.1111/nmo.13708] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 08/06/2019] [Accepted: 08/07/2019] [Indexed: 02/08/2023]
Abstract
The prokinetic effects of 5-HT4 receptor (5-HT4 R) agonists have been utilized clinically for almost three decades to relieve symptoms of constipation. Surprisingly, the mechanism(s) of action of these compounds is still being debated. Recent studies highlight luminal 5-HT4 Rs as an alternative and effective target for these prokinetic agents. These include the study by Shokrollahi et al (2019, Neurogastroenterol Motil, e13598) published in the current issue of Neurogastroenterology and Motility, who found that activation of mucosal 5-HT4 Rs by intraluminal prucalopride, significantly enhanced propulsive motor patterns in rabbit colon. The authors highlight the idea that development of agonists targeting luminal 5-HT4 Rs in the colonic mucosa might be more effective and safer in achieving prokinetic effects on intestinal motility. The purpose of this mini-review is to discuss the evidence for luminal 5-HT4 Rs as an emerging target for prokinetic agents in facilitating propulsive motor patterns in the colon.
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Affiliation(s)
- Rachel M Gwynne
- Department of Physiology, University of Melbourne, Parkville, Vic., Australia
| | - Joel C Bornstein
- Department of Physiology, University of Melbourne, Parkville, Vic., Australia
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3
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Bhattarai Y, Williams BB, Battaglioli EJ, Whitaker WR, Till L, Grover M, Linden DR, Akiba Y, Kandimalla KK, Zachos NC, Kaunitz JD, Sonnenburg JL, Fischbach MA, Farrugia G, Kashyap PC. Gut Microbiota-Produced Tryptamine Activates an Epithelial G-Protein-Coupled Receptor to Increase Colonic Secretion. Cell Host Microbe 2019; 23:775-785.e5. [PMID: 29902441 DOI: 10.1016/j.chom.2018.05.004] [Citation(s) in RCA: 222] [Impact Index Per Article: 44.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 03/28/2018] [Accepted: 05/09/2018] [Indexed: 02/06/2023]
Abstract
Tryptamine, a tryptophan-derived monoamine similar to 5-hydroxytryptamine (5-HT), is produced by gut bacteria and is abundant in human and rodent feces. However, the physiologic effect of tryptamine in the gastrointestinal (GI) tract remains unknown. Here, we show that the biological effects of tryptamine are mediated through the 5-HT4 receptor (5-HT4R), a G-protein-coupled receptor (GPCR) uniquely expressed in the colonic epithelium. Tryptamine increases both ionic flux across the colonic epithelium and fluid secretion in colonoids from germ-free (GF) and humanized (ex-GF colonized with human stool) mice, consistent with increased intestinal secretion. The secretory effect of tryptamine is dependent on 5-HT4R activation and is blocked by 5-HT4R antagonist and absent in 5-HT4R-/- mice. GF mice colonized by Bacteroides thetaiotaomicron engineered to produce tryptamine exhibit accelerated GI transit. Our study demonstrates an aspect of host physiology under control of a bacterial metabolite that can be exploited as a therapeutic modality. VIDEO ABSTRACT.
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Affiliation(s)
- Yogesh Bhattarai
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA
| | - Brianna B Williams
- Department of Bioengineering and ChEM-H, Stanford University, Stanford, CA 94305, USA
| | - Eric J Battaglioli
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA
| | - Weston R Whitaker
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94304, USA
| | - Lisa Till
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA
| | - Madhusudan Grover
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA
| | - David R Linden
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA
| | - Yasutada Akiba
- Department of Medicine, School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA 90073, USA; Brentwood Biomedical Research Institute, Los Angeles, CA 90073, USA
| | - Karunya K Kandimalla
- Department of Pharmaceutics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Nicholas C Zachos
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jonathan D Kaunitz
- Department of Medicine, School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA 90073, USA; Brentwood Biomedical Research Institute, Los Angeles, CA 90073, USA; Department of Surgery, School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Justin L Sonnenburg
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94304, USA
| | - Michael A Fischbach
- Department of Bioengineering and ChEM-H, Stanford University, Stanford, CA 94305, USA
| | - Gianrico Farrugia
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA; Division of Gastroenterology and Hepatology, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Purna C Kashyap
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA.
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4
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Jeong EJ, Chung SY, Hong HN, Oh SW, Sim JY. The novel, potent and highly selective 5-HT 4 receptor agonist YH12852 significantly improves both upper and lower gastrointestinal motility. Br J Pharmacol 2018; 175:485-500. [PMID: 29139561 DOI: 10.1111/bph.14096] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 10/27/2017] [Accepted: 10/31/2017] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE 5-HT4 receptor agonists have been shown to be effective at treating various gastrointestinal tract disorders. However, a lack of selectivity against off-targets has been a limiting factor for their clinical use. EXPERIMENTAL APPROACH The binding affinity and selectivity of YH12852 for human 5-HT4(a) receptor in CHO-K1 cells were evaluated using radioligand binding assays, and agonistic activity was assessed using a β-lactamase reporter system. Contractile activity and propulsive motility were measured in the guinea pig isolated distal colon. Its prokinetic effect on the gastrointestinal tract was evaluated in guinea pigs, dogs and monkeys. Its tissue distribution was evaluated in rats. KEY RESULTS YH12852 exhibited high affinity and potency for human recombinant 5-HT4(a) receptor with high selectivity over other 5-HT and non-5-HT receptors, ion channels, enzymes and transporters. YH12852 induced contractions and increased propulsive motility in guinea pig isolated colon. These effects were abolished by the 5-HT4 receptor antagonist GR113808. YH12852 increased defecation more effectively than prucalopride in guinea pigs and dogs and improved gastric emptying more effectively than mosapride in guinea pigs, dogs and monkeys. YH12852 was highly distributed to the gastrointestinal tract as the target organ. CONCLUSION AND IMPLICATIONS The high in vitro potency and selectivity of YH12852 for 5-HT4 receptor translated into potent in vivo efficacy with good tolerability. YH12852 significantly improved both upper and lower bowel motility in the animal models tested and has the potential to address considerable unmet needs in patients with functional constipation, gastroparesis or both.
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Affiliation(s)
- Eun Jeong Jeong
- Yuhan R&D Institute, Yongin-si, Gyeonggi-do, Republic of Korea
| | - Soo Yong Chung
- Yuhan R&D Institute, Yongin-si, Gyeonggi-do, Republic of Korea
| | - Han Na Hong
- Yuhan R&D Institute, Yongin-si, Gyeonggi-do, Republic of Korea
| | - Se-Woong Oh
- Yuhan R&D Institute, Yongin-si, Gyeonggi-do, Republic of Korea
| | - Jae Young Sim
- Yuhan R&D Institute, Yongin-si, Gyeonggi-do, Republic of Korea
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Bhattarai Y, Schmidt BA, Linden DR, Larson ED, Grover M, Beyder A, Farrugia G, Kashyap PC. Human-derived gut microbiota modulates colonic secretion in mice by regulating 5-HT 3 receptor expression via acetate production. Am J Physiol Gastrointest Liver Physiol 2017; 313:G80-G87. [PMID: 28408644 PMCID: PMC5538830 DOI: 10.1152/ajpgi.00448.2016] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Revised: 03/28/2017] [Accepted: 04/05/2017] [Indexed: 01/31/2023]
Abstract
Serotonin [5-hydroxytryptamine (5-HT)], an important neurotransmitter and a paracrine messenger in the gastrointestinal tract, regulates intestinal secretion by its action primarily on 5-HT3 and 5-HT4 receptors. Recent studies highlight the role of gut microbiota in 5-HT biosynthesis. In this study, we determine whether human-derived gut microbiota affects host secretory response to 5-HT and 5-HT receptor expression. We used proximal colonic mucosa-submucosa preparation from age-matched Swiss Webster germ-free (GF) and humanized (HM; ex-GF colonized with human gut microbiota) mice. 5-HT evoked a significantly greater increase in short-circuit current (ΔIsc) in GF compared with HM mice. Additionally, 5-HT3 receptor mRNA and protein expression was significantly higher in GF compared with HM mice. Ondansetron, a 5-HT3 receptor antagonist, inhibited 5-HT-evoked ΔIsc in GF mice but not in HM mice. Furthermore, a 5-HT3 receptor-selective agonist, 2-methyl-5-hydroxytryptamine hydrochloride, evoked a significantly higher ΔIsc in GF compared with HM mice. Immunohistochemistry in 5-HT3A-green fluorescent protein mice localized 5-HT3 receptor expression to enterochromaffin cells in addition to nerve fibers. The significant difference in 5-HT-evoked ΔIsc between GF and HM mice persisted in the presence of tetrodotoxin (TTX) but was lost after ondansetron application in the presence of TTX. Application of acetate (10 mM) significantly lowered 5-HT3 receptor mRNA in GF mouse colonoids. We conclude that host secretory response to 5-HT may be modulated by gut microbiota regulation of 5-HT3 receptor expression via acetate production. Epithelial 5-HT3 receptor may function as a mediator of gut microbiota-driven change in intestinal secretion.NEW & NOTEWORTHY We found that gut microbiota alters serotonin (5-HT)-evoked intestinal secretion in a 5-HT3 receptor-dependent mechanism and gut microbiota metabolite acetate alters 5-HT3 receptor expression in colonoids.View this article's corresponding video summary at https://www.youtube.com/watch?v=aOMYJMuLTcw&feature=youtu.be.
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Affiliation(s)
- Yogesh Bhattarai
- 1Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota;
| | - Bradley A. Schmidt
- 3Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - David R. Linden
- 3Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Eric D. Larson
- 2Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado; and
| | - Madhusudan Grover
- 1Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota;
| | - Arthur Beyder
- 1Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota;
| | - Gianrico Farrugia
- 1Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota;
| | - Purna C. Kashyap
- 1Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota;
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Isensee J, Krahé L, Moeller K, Pereira V, Sexton JE, Sun X, Emery E, Wood JN, Hucho T. Synergistic regulation of serotonin and opioid signaling contributes to pain insensitivity in Nav1.7 knockout mice. Sci Signal 2017; 10:10/461/eaah4874. [PMID: 28074005 DOI: 10.1126/scisignal.aah4874] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Genetic loss of the voltage-gated sodium channel Nav1.7 (Nav1.7-/-) results in lifelong insensitivity to pain in mice and humans. One underlying cause is an increase in the production of endogenous opioids in sensory neurons. We analyzed whether Nav1.7 deficiency altered nociceptive heterotrimeric guanine nucleotide-binding protein-coupled receptor (GPCR) signaling, such as initiated by GPCRs that respond to serotonin (pronociceptive) or opioids (antinociceptive), in sensory neurons. We found that the nociceptive neurons of Nav1.7 knockout (Nav1.7-/-) mice, but not those of Nav1.8 knockout (Nav1.8-/-) mice, exhibited decreased pronociceptive serotonergic signaling through the 5-HT4 receptors, which are Gαs-coupled GPCRs that stimulate the production of cyclic adenosine monophosphate resulting in protein kinase A (PKA) activity, as well as reduced abundance of the RIIβ regulatory subunit of PKA. Simultaneously, the efficacy of antinociceptive opioid signaling mediated by the Gαi-coupled mu opioid receptors was increased. Consequently, opioids inhibited more efficiently tetrodotoxin-resistant sodium currents, which are important for pain-initiating neuronal activity in nociceptive neurons. Thus, Nav1.7 controls the efficacy and balance of GPCR-mediated pro- and antinociceptive intracellular signaling, such that without Nav1.7, the balance is shifted toward antinociception, resulting in lifelong endogenous analgesia.
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Affiliation(s)
- Jörg Isensee
- Department of Anesthesiology and Intensive Care Medicine, Experimental Anesthesiology and Pain Research, University Hospital of Cologne, Robert Koch Str. 10, 50931 Cologne, Germany.
| | - Leonhardt Krahé
- Department of Anesthesiology and Intensive Care Medicine, Experimental Anesthesiology and Pain Research, University Hospital of Cologne, Robert Koch Str. 10, 50931 Cologne, Germany
| | - Katharina Moeller
- Department of Anesthesiology and Intensive Care Medicine, Experimental Anesthesiology and Pain Research, University Hospital of Cologne, Robert Koch Str. 10, 50931 Cologne, Germany
| | - Vanessa Pereira
- Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK
| | - Jane E Sexton
- Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK
| | - Xiaohui Sun
- Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK
| | - Edward Emery
- Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK
| | - John N Wood
- Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK
| | - Tim Hucho
- Department of Anesthesiology and Intensive Care Medicine, Experimental Anesthesiology and Pain Research, University Hospital of Cologne, Robert Koch Str. 10, 50931 Cologne, Germany.
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7
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Lee HJ, Park KS. [Current Status of Translational Research on Constipation]. THE KOREAN JOURNAL OF GASTROENTEROLOGY 2016; 68:143-7. [PMID: 27646583 DOI: 10.4166/kjg.2016.68.3.143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Constipation is one of the most common gastrointestinal disorders with a prevalence up to 16.5% in the general population. It is frequently multifactorial and the pathophysiologic mechanism of constipation is not fully understood. Many preclinical studies of constipation have used animal models. Translational research using these animal models is essential to the investigation of neurogenic and myogenic mechanisms of colon, and to the estimation of the clinical efficacy of new drugs. In this review, we discuss some of the current translational research projects on constipation using animal models.
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Affiliation(s)
- Hyun Jik Lee
- Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Korea
| | - Kyung Sik Park
- Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Korea
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8
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Böttner M, Barrenschee M, Hellwig I, Harde J, Egberts JH, Becker T, Zorenkov D, Wedel T. The enteric serotonergic system is altered in patients with diverticular disease. Gut 2013; 62:1753-62. [PMID: 23144076 DOI: 10.1136/gutjnl-2012-302660] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Disturbances of the enteric serotonergic system have been implicated in several intestinal motility disorders. Patients with diverticular disease (DD) have been reported to exhibit abnormal intestinal motility and innervation patterns. Gene expression profiles of the serotonergic system and distribution of the serotonin type 4 receptor (5HT-4R) were thus studied in patients with DD. DESIGN Colonic specimens from patients with DD and controls were subjected to quantitative PCR for serotonin receptors 2B, 3A, 4, serotonin transporter and synthesising enzyme tryptophan hydroxylase. Localisation of 5HT-4R was determined by dual-label immunocytochemistry using smooth muscle actin (α-SMA) and pan-neuronal markers (PGP 9.5) and quantitative analysis was carried out. Site-specific gene expression analysis of 5HT-4R was assessed within myenteric ganglia and muscle layers. Correlation of 5HT-4R with muscarinic receptors 2 and 3 (M2R, M3R) messenger RNA expression was determined. RESULTS 5HT-4R mRNA expression was downregulated in the tunica muscularis and upregulated in the mucosa of patients with DD, whereas the other components of the serotonergic system remained unchanged. 5HT-4R was detected in ganglia and muscle layers, but was decreased in the circular muscle layer and myenteric ganglia of patients with DD. 5HT-4R mRNA expression correlated with M2R/M3R mRNA expression in controls, but not in patients with DD. CONCLUSIONS The serotonergic system is compromised in DD. Altered expression of 5HT-4R at mRNA and protein levels may contribute to intestinal motor disturbances reported in patients with DD. The findings support the hypothesis that DD is associated and possibly promoted by an enteric neuromuscular pathology.
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MESH Headings
- Aged
- Case-Control Studies
- Colon, Sigmoid/metabolism
- Colon, Sigmoid/physiopathology
- Diverticulum, Colon/metabolism
- Diverticulum, Colon/physiopathology
- Enteric Nervous System/metabolism
- Enteric Nervous System/physiopathology
- Female
- Humans
- Male
- Middle Aged
- Polymerase Chain Reaction
- Receptors, Serotonin, 5-HT2/metabolism
- Receptors, Serotonin, 5-HT2/physiology
- Receptors, Serotonin, 5-HT3/metabolism
- Receptors, Serotonin, 5-HT3/physiology
- Receptors, Serotonin, 5-HT4/metabolism
- Receptors, Serotonin, 5-HT4/physiology
- Serotonergic Neurons/metabolism
- Serotonergic Neurons/physiology
- Serotonin Plasma Membrane Transport Proteins/metabolism
- Serotonin Plasma Membrane Transport Proteins/physiology
- Transcriptome/physiology
- Tryptophan Hydroxylase/metabolism
- Tryptophan Hydroxylase/physiology
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Affiliation(s)
- Martina Böttner
- Institute of Anatomy, Christian-Albrechts-University of Kiel, , Kiel, Germany
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9
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Priem EKV, Maeyer JHD, Vandewoestyne M, Deforce D, Lefebvre RA. Predominant mucosal expression of 5-HT4(+h) receptor splice variants in pig stomach and colon. World J Gastroenterol 2013; 19:3747-3760. [PMID: 23840113 PMCID: PMC3699052 DOI: 10.3748/wjg.v19.i24.3747] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 11/21/2012] [Accepted: 12/17/2012] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate cellular 5-HT4(-h/+h) receptor distribution, particularly in the epithelial layer, by laser microdissection and polymerase chain reaction (PCR) in porcine gastrointestinal (GI) tissues.
METHODS: A stepwise approach was used to evaluate RNA quality and to study cell-specific 5-HT4 receptor mRNA expression in the porcine gastric fundus and colon descendens. After freezing, staining and laser microdissection and pressure catapulting (LMPC), RNA quality was evaluated by the Experion automated electrophoresis system. 5-HT4 receptor and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expressions were examined by endpoint reverse transcription (RT)-PCR in mucosal and muscle-myenteric plexus (MMP) tissue fractions, in mucosal and MMP parts of hematoxylin and eosin (HE) stained tissue sections and in microdissected patches of the epithelial and circular smooth muscle cell layer in these sections. Pig gastric fundus tissue sections were also stained immunohistochemically (IHC) for enterochromaffin cells (EC cells; MAB352); these cells were isolated by LMPC and examined by endpoint RT-PCR.
RESULTS: After HE staining, the epithelial and circular smooth muscle cell layer of pig colon descendens and the epithelial cell layer of gastric fundus were identified morphologically and isolated by LMPC. EC cells of pig gastric fundus were successfully stained by IHC and isolated by LMPC. Freezing, HE and IHC staining, and LMPC had no influence on RNA quality. 5-HT4 receptor and GAPDH mRNA expressions were detected in mucosa and MMP tissue fractions, and in mucosal and MMP parts of HE stained tissue sections of pig colon descendens and gastric fundus. In the mucosa tissue fractions of both GI regions, the expression of h-exon containing receptor [5-HT4(+h) receptor] mRNA was significantly higher (P < 0.01) compared to 5-HT4(-h) receptor expression, and a similar trend was obtained in the mucosal part of HE stained tissue sections. Large microdissected patches of the epithelial and circular smooth muscle cell layer of pig colon descendens and of the epithelial cell layer of pig gastric fundus, also showed 5-HT4 receptor and GAPDH mRNA expression. No 5-HT4 receptor mRNA expression was detected in gastric LMPC-isolated EC cells from IHC stained tissues, which cells were positive for GAPDH.
CONCLUSION: Porcine GI mucosa predominantly expresses 5-HT4(+h) receptor splice variants, suggesting their contribution to the 5-HT4 receptor-mediated mucosal effects of 5-HT.
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10
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Tajika M, Niwa Y, Bhatia V, Kawai H, Kondo S, Sawaki A, Mizuno N, Hara K, Hijioka S, Matsumoto K, Kobayashi Y, Saeki A, Akabane A, Komori K, Yamao K. Efficacy of mosapride citrate with polyethylene glycol solution for colonoscopy preparation. World J Gastroenterol 2012; 18:2517-25. [PMID: 22654449 PMCID: PMC3360450 DOI: 10.3748/wjg.v18.i20.2517] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 09/22/2011] [Accepted: 02/27/2012] [Indexed: 02/06/2023] Open
Abstract
AIM: To evaluate the efficacy and safety of adjunctive mosapride citrate for bowel preparation before colonoscopy.
METHODS: We conducted a randomized, double-blind, placebo-controlled study with mosapride in addition to polyethylene glycol (PEG)-electrolyte solution. Of 250 patients undergoing colonoscopy, 124 were randomized to receive 2 L PEG plus 15 mg of mosapride citrate (mosapride group), and 126 received 2 L PEG plus placebo (placebo group). Patients completed a questionnaire reporting the acceptability and tolerability of the bowel preparation process. The efficacy of bowel preparation was assessed by colonoscopists using a 5-point scale based on Aronchick’s criteria. The primary end point was optimal bowel preparation rates (scores of excellent/good/fair vs poor/inadequate).
RESULTS: A total of 249 patients were included in the analysis. In the mosapride group, optimal bowel preparation rates were significantly higher in the left colon compared with the placebo group (78.2% vs 65.6%, P < 0.05), but not in the right colon (76.5% vs 66.4%, P = 0.08). After excluding patients with severe constipation, there was a significant difference in bowel preparation in both the left and right colon (82.4% vs 66.7%, 80.8% vs 67.5%, P < 0.05, P < 0.01). The incidence of adverse events was similar in both groups. Among the subgroup who had previous colonoscopy experience, a significantly higher number of patients in the mosapride group felt that the current preparation was easier compared with patients in the placebo group (34/72 patients vs 24/74 patients, P < 0.05).
CONCLUSION: Mosapride citrate may be an effective and safe adjunct to PEG-electrolyte solution that leads to improved quality of bowel preparation, especially in patients without severe constipation.
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Toyomasu Y, Mochiki E, Morita H, Ogawa A, Yanai M, Ohno T, Fujii T, Tsutsumi S, Asao T, Kuwano H. Mosapride citrate improves postoperative ileus of patients with colectomy. J Gastrointest Surg 2011; 15:1361-7. [PMID: 21607794 DOI: 10.1007/s11605-011-1567-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Accepted: 05/11/2011] [Indexed: 02/06/2023]
Abstract
BACKGROUND AND AIMS Postoperative ileus is a transient bowel dysmotility that occurs following many types of operations and is a common complication of gastrointestinal surgery. Mosapride citrate is an agonist of the 5-hydroxytryptamine 4 receptor and accelerates upper gut motility. No study has evaluated its effect on gastrointestinal motility after surgery. The aim of this study was to investigate whether mosapride citrate reduces the duration of postoperative ileus. METHODS Thirty patients with colon cancer who underwent colectomy were divided into two groups: the mosapride group and the control group. The mosapride group received mosapride 15 mg by mouth with a minimal amount of water three times a day, starting on postoperative day 1. The control group received only a minimal amount of water on the same schedule. Patients were allowed to resume oral feeding on postoperative day 4. Postoperative time to first flatus and defecation were evaluated, and the amount of food intake was observed. Gastrointestinal motility was recorded on postoperative day 8. RESULTS The appearance ratio of interdigestive migrating contractions and the motility index at the antrum and duodenum were significantly higher in the mosapride group than in the control group. The time to first flatus and defecation were significantly shorter in the mosapride group than in the control group. The amount of food intake on postoperative days 6 and 7 was significantly larger in the mosapride group than in the control group. CONCLUSION Mosapride citrate reduces the duration of postoperative ileus and may improve outcomes after gastrointestinal surgery.
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Affiliation(s)
- Yoshitaka Toyomasu
- Department of General Surgical Science (Surgery I), Graduate School of Medicine, Gunma University, Gunma, 371-8511, Japan.
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12
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Velarde E, Delgado MJ, Alonso-Gómez AL. Serotonin-induced contraction in isolated intestine from a teleost fish (Carassius auratus): characterization and interactions with melatonin. Neurogastroenterol Motil 2010; 22:e364-73. [PMID: 20939846 DOI: 10.1111/j.1365-2982.2010.01605.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND Serotonin (5-HT) plays a critical role in several gastrointestinal functions in vertebrates. In teleosts lacking enterochromaffin cells, intestinal 5-HT originates from serotonergic enteric neurons. In the present study, the foregut of a stomachless teleost, the goldfish (Carassius auratus), was used to evaluate the in vitro effect of 5-HT on fish intestinal motility. We also studied the role of melatonin (MEL), an indoleamine sharing the biosynthetic pathway with 5-HT, as regulator of serotonergic activity. METHODS An organ bath system, with longitudinal strips from the goldfish intestinal bulb attached to an isometric transducer was used to record foregut smooth muscle contractions. KEY RESULTS Concentration-dependent curves of the contractile response exerted by 5-HT and its agonists, 5-methoxytryptamine (5-MT) and 5-carboxamidotryptamine (5-CT), suggest a receptor-mediated action, supported by the blockade by a general 5-HT antagonist, methysergide. The 5-HT-induced contraction was abolished in the presence of atropine, revealing the involvement of cholinergic transmission in gut actions of 5-HT. Furthermore, MEL inhibited the contractile effect of 5-HT and its agonists by up to 50%, which was counteracted by MEL antagonists. CONCLUSIONS & INFERENCES We can provisionally propose that at least two different 5-HT receptor subtypes are involved in fish intestinal motility, a 5-HT₄-like (5-MT-preferring) and a 5-HT₇-like (5-CT- and fluphenazine-sensitive) receptor. In summary, our results indicate that 5-HT regulates the contractile activity of goldfish foregut through specific receptors located in cholinergic neurons, and that MEL can modulate these serotonergic actions through high-affinity membrane receptors.
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Affiliation(s)
- E Velarde
- Departamento de Fisiología (Fisiología Animal II), Facultad de Biología, Universidad Complutense, Madrid, Spain
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13
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Nedi T, White PJ, Coupar IM, Irving HR. Tissue dependent differences in G-protein coupled receptor kinases associated with 5-HT4 receptor desensitization in the rat gastro-intestinal tract. Biochem Pharmacol 2010; 81:123-33. [PMID: 20836992 DOI: 10.1016/j.bcp.2010.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 08/31/2010] [Accepted: 09/02/2010] [Indexed: 12/12/2022]
Abstract
Desensitization of 5-HT(4) receptors is regulated by G-protein coupled receptor kinases (GRKs). However, the specific GRK(s) that regulates the desensitization of 5-HT(4) receptors in the in vivo setting is unknown. We investigated the in situ expression of 5-HT(4) receptors and the GRKs in the rat gastrointestinal tract using immunohistochemistry and their interaction using coimmunoprecipitation. 5-HT(4) receptors were expressed in the tunica muscularis mucosae of the oesophagus, longitudinal muscle, myenteric plexus, circular muscle, submucosal plexus and muscularis mucosae of both the proximal and distal colon. GRK2 was expressed in longitudinal muscle and occasionally in myenteric plexus whilst GRK5 showed limited expression in the nerve endings of the myenteric plexus and submucosal plexus of the colon. GRK3 was expressed in the tunica muscularis mucosae of the oesophagus, circular muscle, submucosal plexus and muscularis mucosae of the colon. GRK6 was expressed in the tunica muscularis mucosae of the oesophagus, longitudinal muscle, circular muscle, and muscularis mucosae of the colon. Stimulation of tunica muscularis mucosae of the oesophagus and distal colon using the 5-HT(4) receptor agonist, tegaserod, followed by analysis of the 5-HT(4) receptor antibody immunoprecipitate, revealed the coimmunoprecipitation of GRK6 with 5-HT(4) receptors in the tunica muscularis mucosae of oesophagus while GRK2 and GRK6 were coimmunoprecipitated with 5-HT(4) receptors in the distal colon. This study indicates that GRK6 may be involved in the regulation of the desensitization of 5-HT(4) receptors in the rat oesophagus whilst GRK2 and GRK6 may be involved in regulation of the desensitization of 5-HT(4) receptors in the distal colon.
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Affiliation(s)
- Teshome Nedi
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Vic 3052, Australia
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14
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Mine Y, Morikage K, Oku S, Yoshikawa T, Shimizu I, Yoshida N. Effect of mosapride citrate hydrate on the colon cleansing action of polyethylene glycol electrolyte lavage solution (PEG-ELS) in guinea pigs. J Pharmacol Sci 2009; 110:415-23. [PMID: 19602846 DOI: 10.1254/jphs.08331fp] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Polyethylene glycol electrolyte lavage solution (PEG-ELS) is widely used for colon cleansing prior to colonoscopy and colonic surgery. It has recently been shown that coadministration of PEG-ELS and mosapride citrate hydrate (mosapride), a selective 5-HT(4)-receptor agonist, is clinically useful for barium enema examination as it allows adequate barium coating. However, there is no report showing that mosapride has beneficial effects on colon cleansing and its underlying mechanism in experimental animals. In the present study, we investigated the effects of mosapride on colonic transit and on the colon cleansing action of PEG-ELS in guinea pigs. Mosapride (10 - 20 mg/kg, i.g.) significantly enhanced colonic transit rate in guinea pigs. Although PEG-ELS alone showed adequate colon cleansing action, excess fluid remained in the colon. Coadministration of mosapride (20 mg/kg) and PEG-ELS, regardless of mosapride timing, reduced colonic content weight (dry residue and water amount) as compared to PEG-ELS alone. These findings suggest that mosapride enhances the colon cleansing action of PEG-ELS via an increase in colonic transit in guinea pigs, that is, it reduces not only fecal residue but also excessive fluid in the colonic lumen. It is therefore believed that coadministration of mosapride and PEG-ELS can allow better visualization in barium enema examination.
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Affiliation(s)
- Yukiko Mine
- Discovery Pharmacology II, Pharmacology Research Laboratories, Dainippon Sumitomo Pharma Co. Ltd., 33-94 Enoki-cho, Suita, Osaka, Japan.
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15
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Abstract
5-Hydroxytryptamine (5-HT) released from enterochromaffin cells regulates gastrointestinal function in either an excitatory or inhibitory manner. 5-HT(3) and 5-HT(4) receptors in the gut have been the focus of clinical studies on the management of gastrointestinal motility disorders. 5-HT stimulates intestinal propulsive reflexes through 5-HT(4) receptors. 5-HT(4) receptor agonists can stimulate upper or lower gut motility, depending on their selectivity and affinity. In the guinea pig colon, the distribution of 5-HT(4) receptors in the myenteric plexus and circular muscle layer differs between the proximal and distal regions. 5-HT stimulates intestinal motility via excitatory neurons while causing relaxation of the circular muscle via 5-HT(4) receptors. In the light of these findings on the distribution of 5-HT(4) receptors, the effects of receptor agonist compounds could vary depending on the species of experimental animal and the anatomical region studied.
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Affiliation(s)
- Hee Sun Kim
- Yongdong Severance Hospital Health Promotion Center, Yonsei University College of Medicine, Seoul, Korea
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16
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Heitzmann D, Warth R. Physiology and pathophysiology of potassium channels in gastrointestinal epithelia. Physiol Rev 2008; 88:1119-82. [PMID: 18626068 DOI: 10.1152/physrev.00020.2007] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Epithelial cells of the gastrointestinal tract are an important barrier between the "milieu interne" and the luminal content of the gut. They perform transport of nutrients, salts, and water, which is essential for the maintenance of body homeostasis. In these epithelia, a variety of K(+) channels are expressed, allowing adaptation to different needs. This review provides an overview of the current literature that has led to a better understanding of the multifaceted function of gastrointestinal K(+) channels, thereby shedding light on pathophysiological implications of impaired channel function. For instance, in gastric mucosa, K(+) channel function is a prerequisite for acid secretion of parietal cells. In epithelial cells of small intestine, K(+) channels provide the driving force for electrogenic transport processes across the plasma membrane, and they are involved in cell volume regulation. Fine tuning of salt and water transport and of K(+) homeostasis occurs in colonic epithelia cells, where K(+) channels are involved in secretory and reabsorptive processes. Furthermore, there is growing evidence for changes in epithelial K(+) channel expression during cell proliferation, differentiation, apoptosis, and, under pathological conditions, carcinogenesis. In the future, integrative approaches using functional and postgenomic/proteomic techniques will help us to gain comprehensive insights into the role of K(+) channels of the gastrointestinal tract.
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Affiliation(s)
- Dirk Heitzmann
- Institute of Physiology and Clinic and Policlinic for Internal Medicine II, Regensburg, Germany
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17
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Kim HS, Choi EJ, Park H. The effect of mosapride citrate on proximal and distal colonic motor function in the guinea-pig in vitro. Neurogastroenterol Motil 2008; 20:169-76. [PMID: 17931343 DOI: 10.1111/j.1365-2982.2007.00996.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Mosapride citrate (mosapride), a substituted benzamide, is a selective 5-HT(4) receptor agonist, and is known to have prokinetic properties on the stomach. However, it is unclear whether mosapride also has a prokinetic effect on the colon. We previously found that mosapride significantly shortened colonic transit time in the guinea-pig, an animal with a distribution of colonic 5-HT(4) receptors similar to that of a human. So, we aimed to separately evaluate the effect of mosapride on proximal and distal colonic motor function in the guinea-pig. Proximal (approximately 8 cm from the ileocolic junction) and distal colon (approximately 8 cm from the anus) were removed. Both ends of the colon were connected to a chamber containing a Krebs-Henseleit solution. To measure colonic transit time, artificial faeces were inserted into the oral side of the lumen and moved towards the anal side by intraluminal perfusion via a peristaltic pump. A total of 6 cm of transit was observed and time was measured in 2 cm increments. A tissue bath study, using electrical stimulation, was performed to estimate the contractile activity of the circular musculature of the colon. Immunohistochemical staining for 5-HT(4) receptors was performed in the myenteric plexus and circular muscle in both proximal and distal colon, and the stained area was measured using a microscope and computer software. Mosapride enhanced contraction at 10(-9) to 10(-7) mol L(-1), coinciding with rapid transit both in proximal and distal colon. This pattern was more prominent in proximal colon. At the high dose (10(-6) mol L(-1)) mosapride had little or no effect on colonic contraction. This stimulatory effect was attenuated by GR113808, atropine and tetrodotoxin. In the myenteric plexus, the density of 5-HT(4) receptors was significantly greater in the proximal colon than in the distal colon, but in circular muscle the density was greater in the distal colon. Thus, mosapride accelerates transit through increased contraction in the proximal colon more than distal colon. The different distribution of neuronal and muscular 5-HT(4) receptors may support these findings. Therefore, mosapride may be a useful alternative to tegaserod and cisapride for constipation.
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Affiliation(s)
- H S Kim
- Department of Internal Medicine, Yonsei Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea
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18
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Mikami T, Ochi Y, Suzuki K, Saito T, Sugie Y, Sakakibara M. 5-Amino-6-chloro-N-[(1-isobutylpiperidin-4-yl)methyl]-2-methylimidazo[1,2-α]pyridine-8-carboxamide (CJ-033,466), a Novel and Selective 5-Hydroxytryptamine4 Receptor Partial Agonist: Pharmacological Profile in Vitro and Gastroprokinetic Effect in Conscious Dogs. J Pharmacol Exp Ther 2008; 325:190-9. [DOI: 10.1124/jpet.107.133850] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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19
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Vickery RG, Mai N, Kaufman E, Beattie DT, Pulido-Rios T, O'Keefe M, Humphrey PPA, Smith JAM. A comparison of the pharmacological properties of guinea-pig and human recombinant 5-HT4 receptors. Br J Pharmacol 2007; 150:782-91. [PMID: 17293885 PMCID: PMC2013860 DOI: 10.1038/sj.bjp.0707154] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Revised: 11/22/2006] [Accepted: 12/11/2006] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND AND PURPOSE 5-HT(4) receptor agonists are used therapeutically to treat disorders of reduced gastrointestinal motility. Since such compounds are evaluated in guinea-pigs, we cloned, expressed and pharmacologically characterized the guinea-pig 5-HT(4) and human 5-HT(4(b)) splice variant, which share 95% homology. The functional properties of guinea-pig 5-HT(4(b)) receptors were compared with native receptors in guinea-pig colon. EXPERIMENTAL APPROACH Membrane radioligand binding and whole cell cAMP accumulation assays were used to determine the affinities, potencies and intrinsic activities (IA). Contraction of the guinea-pig distal colon longitudinal muscle myenteric plexus preparation (LMMP) was monitored to evaluate functional activity. KEY RESULTS pK(i) values for guinea-pig and human recombinant receptors, and guinea-pig striatum 5-HT(4) receptors, were in agreement, as were the potency and IA values for guinea-pig and human 5-HT(4) receptors expressed at a similar density ( approximately 0.2 pmol mg(-1) protein). Tegaserod was a potent (pEC(50)=8.4 and 8.7, respectively), full agonist at both guinea-pig and human 5-HT(4) receptors. In contrast, in the LMMP preparation, tegaserod was a potent, partial agonist (pEC(50)=8.2; IA=66%). CONCLUSIONS AND IMPLICATIONS Close agreement between the pharmacological properties of guinea-pig and human 5-HT(4) receptors support the use of guinea-pig model systems for the identification of 5-HT(4) receptor therapeutics. However, the mechanisms underlying the different agonist properties of tegaserod in recombinant and isolated tissue preparations, and the extent to which these impact the clinical efficacy of tegaserod as a prokinetic agent, remain to be determined.
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Affiliation(s)
- R G Vickery
- Department of Molecular and Cell Biology, Theravance Inc. South San Francisco, CA, USA
| | - N Mai
- Department of Molecular and Cell Biology, Theravance Inc. South San Francisco, CA, USA
| | - E Kaufman
- Department of Molecular and Cell Biology, Theravance Inc. South San Francisco, CA, USA
| | - D T Beattie
- Department of Pharmacology, Theravance Inc. South San Francisco, CA, USA
| | - T Pulido-Rios
- Department of Pharmacology, Theravance Inc. South San Francisco, CA, USA
| | - M O'Keefe
- Department of Molecular and Cell Biology, Theravance Inc. South San Francisco, CA, USA
| | - P P A Humphrey
- Department of Molecular and Cell Biology, Theravance Inc. South San Francisco, CA, USA
| | - J A M Smith
- Department of Molecular and Cell Biology, Theravance Inc. South San Francisco, CA, USA
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Wang L, Martínez V, Kimura H, Taché Y. 5-Hydroxytryptophan activates colonic myenteric neurons and propulsive motor function through 5-HT4 receptors in conscious mice. Am J Physiol Gastrointest Liver Physiol 2007; 292:G419-28. [PMID: 16990446 DOI: 10.1152/ajpgi.00289.2006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Serotonin [5-hydroxytryptamine (5-HT)] acts as a modulator of colonic motility and secretion. We characterized the action of the 5-HT precursor 5-hydroxytryptophan (5-HTP) on colonic myenteric neurons and propulsive motor activity in conscious mice. Fos immunoreactivity (IR), used as a marker of neuronal activation, was monitored in longitudinal muscle/myenteric plexus whole mount preparations of the distal colon 90 min after an intraperitoneal injection of 5-HTP. Double staining of Fos IR with peripheral choline acetyltransferase (pChAT) IR or NADPH-diaphorase activity was performed. The injection of 5-HTP (0.5, 1, 5, or 10 mg/kg ip) increased fecal pellet output and fluid content in a dose-related manner, with a peak response observed within the first 15 min postinjection. 5-HTP (0.5-10 mg/kg) dose dependently increased Fos expression in myenteric neurons, with a maximal response of 9.9 +/- 1.0 cells/ganglion [P < 0.05 vs. vehicle-treated mice (2.3 +/- 0.6 cells/ganglion)]. There was a positive correlation between Fos expression and fecal output. Of Fos-positive ganglionic cells, 40 +/- 4% were also pChAT positive and 21 +/- 5% were NADPH-diaphorase positive in response to 5-HTP, respectively. 5-HTP-induced defecation and Fos expression were completely prevented by pretreatment with the selective 5-HT4 antagonist RS-39604. These results show that 5-HTP injected peripherally increases Fos expression in different populations of cholinergic and nitrergic myenteric neurons in the distal colon and stimulates propulsive colonic motor function through 5-HT4 receptors in conscious mice. These findings suggest an important role of activation of colonic myenteric neurons in the 5-HT4 receptor-mediated colonic propulsive motor response.
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Affiliation(s)
- L Wang
- Digestive Diseases Research Center and Center for Neurovisceral Sciences and Woman's Health, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, USA.
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21
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Gershon MD, Tack J. The serotonin signaling system: from basic understanding to drug development for functional GI disorders. Gastroenterology 2007; 132:397-414. [PMID: 17241888 DOI: 10.1053/j.gastro.2006.11.002] [Citation(s) in RCA: 1046] [Impact Index Per Article: 61.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2006] [Accepted: 11/06/2006] [Indexed: 12/11/2022]
Abstract
Serotonin is an important gastrointestinal signaling molecule. It is a paracrine messenger utilized by enterochromaffin (EC) cells, which function as sensory transducers. Serotonin activates intrinsic and extrinsic primary afferent neurons to, respectively, initiate peristaltic and secretory reflexes and to transmit information to the central nervous system. Serotonin is also a neurotransmitter utilized by a system of long descending myenteric interneurons. Serotonin is synthesized through the actions of 2 different tryptophan hydroxylases, TpH1 and TpH2, which are found, respectively, in EC cells and neurons. Serotonin is inactivated by the serotonin reuptake transporter (SERT)-mediated uptake into enterocytes or neurons. The presence of many serotonin receptor subtypes enables selective drugs to be designed to therapeutically modulate gastrointestinal motility, secretion, and sensation. Current examples include tegaserod, a 5-HT(4) partial agonist, which has been approved for treatment of irritable bowel syndrome (IBS) with constipation in women and for chronic constipation in men and women. The 5-HT(3) antagonists, granisetron and ondansetron, are useful in combating the nausea associated with cancer chemotherapy, and alosetron is employed in the treatment of IBS with diarrhea. Serotonergic signaling abnormalities have also been putatively implicated in the pathogenesis of functional bowel diseases. Other compounds, for which efficacy has not been rigorously established, but which may have value, include tricyclic antidepressants and serotonin selective reuptake inhibitors to combat IBS, and 5-HT(1) agonists, which enhance gastric accommodation, to treat functional dyspepsia. The initial success encountered with serotonergic agents holds promise for newer and more potent insights and therapies of brain-gut disorders.
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Affiliation(s)
- Michael D Gershon
- Department of Pathology & Cell Biology, Columbia University, College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA.
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22
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Engel L, Kobel B, Ontsouka EC, Graber HU, Blum JW, Steiner A, Meylan M. Distribution of mRNA coding for 5-hydroxytryptamine receptor subtypes in the intestines of healthy dairy cows and dairy cows with cecal dilatation-dislocation. Am J Vet Res 2006; 67:95-101. [PMID: 16426218 DOI: 10.2460/ajvr.67.1.95] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To investigate the distribution of mRNA coding for 7 subtypes of 5-hydroxytryptamine receptors (5-HTRs) in the intestines of healthy dairy cows and dairy cows with cecal dilatation-dislocation (CDD). SAMPLE POPULATION Full-thickness intestinal wall biopsy specimens were obtained from the ileum, cecum, proximal loop of the ascending colon, and external loop of the spiral colon (ELSC) of 15 cows with CDD (group 1) and 15 healthy dairy cows allocated to 2 control groups (specimens collected during routine laparotomy [group 2] or after cows were slaughtered [group 3]). PROCEDURE Amounts of mRNA coding for 7 subtypes of 5-HTRs (5-HT1A, 5-HT1B, 5-HT1D, 5-HT1F, 5-HT2A, 5-HT2B, and 5-HT4) were measured by quantitative real-time reverse transcriptase-PCR assay. Results were expressed as the percentage of mRNA expression of a housekeeping gene. RESULTS Expression of mRNA coding for 5-HTR1B, 5-HTR2B, and 5-HTR4 was significantly lower in cows with CDD than in healthy cows. For 5-HTR2B and 5-HTR4, significant differences between cows with CDD and control cows were most pronounced for the ELSC. Expression of mRNA for 5-HTR1D, 5-HTR1F, and 5-HTR2A was extremely low in all groups, and mRNA for 5-HTR1A was not detected. CONCLUSIONS AND CLINICAL RELEVANCE Relative concentrations of mRNA coding for 5-HTR1B, 5-HT2B, and 5-HTR4 were significantly lower in the intestines of cows with CDD than in the intestines of healthy dairy cows, especially for 5-HT2B and 5-HTR4 in the ELSC. This supports the hypothesis that serotonergic mechanisms, primarily in the spiral colon, are implicated in the pathogenesis of CDD.
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Affiliation(s)
- Ladina Engel
- Clinic for Ruminants, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Berne, Bremgartenstrasse 109a, PO Box 8466, 3001 Berne, Switzerland
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Mader R, Kocher T, Haier J, Wieczorek G, Pfannkuche HJ, Ito M. Investigation of serotonin type 4 receptor expression in human and non-human primate gastrointestinal samples. Eur J Gastroenterol Hepatol 2006; 18:945-50. [PMID: 16894306 DOI: 10.1097/01.meg.0000228975.87645.27] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND The serotonin type 4 (5-HT4) receptor has been associated with functions of the gastrointestinal tract such as modulation of the peristaltic reflex, smooth muscle tone, intestinal secretion and visceral sensitivity. The activation of peripheral 5-HT4 receptors with agonists such as tegaserod has been shown to accelerate gastric emptying and improve symptoms of constipation in animals and humans. However, detailed data on the expression profile and on the localization of this receptor subtype are lacking so far. OBJECTIVE To study the pattern and expression levels of 5-HT4 receptor messenger RNA expression in the gut. METHOD Normal tissue samples were collected from the whole gastrointestinal tract of patients undergoing abdominal surgery and, in addition, of monkeys. We performed a comprehensive analysis of 5-HT4 receptor expression by quantitative reverse transcription-polymerase chain reaction, using human and non-human primate tissues from the oesophagus to the rectum. In addition, the brain and heart of non-human primates were analysed. RESULTS Significantly higher levels of 5-HT4 receptor mRNA were measured in the human stomach, duodenum, jejunum, ileum and caecum and also in the corresponding non-human primate gut segments, ranging from 2- to 12-fold compared with the liver. No differences were found between females and males of both human and non-human primates. CONCLUSIONS These results show 5-HT4 receptor mRNA expression throughout the gastrointestinal tract in humans and primates, and also support the preclinical and clinical findings of 5-HT4 receptors ligands exhibiting multiple effects throughout the gastrointestinal tract.
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Affiliation(s)
- Robert Mader
- Novartis Institutes for BioMedical Research, GI Department, Basel, Switzerland
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24
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Cellek S, John AK, Thangiah R, Dass NB, Bassil AK, Jarvie EM, Lalude O, Vivekanandan S, Sanger GJ. 5-HT4 receptor agonists enhance both cholinergic and nitrergic activities in human isolated colon circular muscle. Neurogastroenterol Motil 2006; 18:853-61. [PMID: 16918765 DOI: 10.1111/j.1365-2982.2006.00810.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Previous studies have demonstrated mixed inhibitory and facilitatory effects of 5-hydroxytryptamine-4 (5-HT(4)) receptor agonists on electrical field stimulation (EFS)-induced responses in human isolated colon. Here we report three types of responses to EFS in human isolated colon circular muscle: monophasic cholinergic contraction during EFS, biphasic response (nitrergic relaxation during EFS followed by cholinergic contraction after termination of EFS) and triphasic response (cholinergic contraction followed by nitrergic relaxation during EFS and a tachykininergic contraction after EFS). The effects of two 5-HT(4) receptor agonists, prucalopride and tegaserod were then investigated on monophasic responses only. Each compound inhibited contractions during EFS in a concentration-dependent manner. In the presence of N(omega)-nitro-l-arginine methyl ester (l-NAME) however, prucalopride and tegaserod enhanced the contractions in a concentration-dependent manner. In strips where the tone was elevated with substance-P and treated with scopolamine, EFS-induced relaxations were enhanced by the two agonists. The above observed effects by the two agonists were abolished by 5-HT(4) receptor antagonist SB-204070. The two agonists did not alter the tone raised by substance-P in the presence of scopolamine and l-NAME and did not affect carbachol-induced contractions in the presence of tetrodotoxin. These results suggest that in the circular muscle of human colon, 5-HT(4) receptor agonists simultaneously facilitate the activity of neurones which release the inhibitory and excitatory neurotransmitters, nitric oxide and acetylcholine respectively.
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Affiliation(s)
- S Cellek
- Neurology and Gastroenterology Centre of Excellence in Drug Discovery, GlaxoSmithKline, Harlow, Essex, UK.
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25
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Kojima Y, Nakagawa T, Katsui R, Fujii H, Nakajima Y, Takaki M. A 5-HT4 agonist, mosapride, enhances intrinsic rectorectal and rectoanal reflexes after removal of extrinsic nerves in guinea pigs. Am J Physiol Gastrointest Liver Physiol 2005; 289:G351-60. [PMID: 15817810 DOI: 10.1152/ajpgi.00532.2004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Distension-evoked reflex of rectorectal (R-R) contractions and rectointernal anal sphincter (R-IAS) relaxations can be generated in guinea pigs through an extrinsic sacral excitatory neural pathway (pelvic nerves) as well as intrinsic cholinergic excitatory and nitrergic inhibitory pathways. The aim of the present study was to create intrinsic R-R and R-IAS reflex models by pithing (destruction of the lumbar and sacral cords; PITH) and to evaluate whether the prokinetic benzamide mosapride, a 5-HT(4) receptor agonist, enhances these reflexes. The mechanical activities of the R-R and R-IAS were recorded in the anesthetized guinea pig on days 2-9 after PITH. Although the basal rectal pressure at distension after PITH was significantly lower than control, the reflex indexes of R-R contractions and synchronous R-IAS relaxations were unchanged between days 4 and 9 after PITH. The frequency of spontaneous rectal and IAS motility were also unchanged. Immunohistochemical studies revealed that the distribution of myenteric and intramuscular interstitial cells of Cajal (ICC) were not altered after PITH. Mosapride (0.1-1.0 mg/kg iv) dose-dependently increased both intrinsic R-R (maximum: 1.82) and R-IAS reflex indexes (maximum: 2.76) from control (1.0) 6-9 days after PITH. The 5-HT(4) receptor antagonist, GR-113808 (1.0 mg/kg iv) decreased the R-R and R-IAS reflex indexes by approximately 50% and antagonized the effect of mosapride (1.0 mg/kg iv). The present results indicate that mosapride moderately enhanced intrinsic R-R and R-IAS reflexes functionally compensated after deprivation of extrinsic nerves, mediated through endogenously active intrinsic 5-HT(4) receptors.
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Affiliation(s)
- Yu Kojima
- Dept. of Physiology II, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521, Japan
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26
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Leclere PG, Prins NH, Schuurkes JAJ, Lefebvre RA. 5-HT4 receptors located on cholinergic nerves in human colon circular muscle. Neurogastroenterol Motil 2005; 17:366-75. [PMID: 15916624 DOI: 10.1111/j.1365-2982.2005.00621.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
5-Hydroxytryptamine 4 (5-HT4) receptor agonists promote colonic propulsion. The alteration of circular muscle (CM) motility underlying this involves inhibition of contractility via smooth muscle 5-HT4 receptors and proximal colonic motility stimulation, the mechanism of the latter not having been characterized. Our aim was to identify and characterize a 5-HT4 receptor-mediated stimulation of human colon CM contractile activity. 5-HT4 receptor ligands were tested on electrical field stimulation (EFS)-induced contractions of human colonic muscle strips cut in the circular direction (called 'whole tissue' strips). Additionally, after incubation of tissues with [3H]-choline these compounds were tested on EFS-induced release of tritium in whole tissue strips and in 'isolated' CM strips, obtained by superficial cutting in the CM layer. Tetrodotoxin and atropine blocked EFS-induced contractions of whole tissue CM strips. Prucalopride (0.3 micromol L-1) evoked a heterogenous response on EFS-induced contraction, ranging from inhibition (most frequently observed) to enhancement. In the release experiments, EFS-induced tritium efflux was blocked by tetrodotoxin. Prucalopride increased EFS-induced tritium and [3H]-acetylcholine efflux in whole tissue and in isolated CM strips. All effects of prucalopride were antagonized by the selective 5-HT4 receptor antagonist GR113808. The results obtained indicate the presence of excitatory 5-HT4 receptors on cholinergic nerves within the CM of human colon.
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Affiliation(s)
- P G Leclere
- Heymans Institute of Pharmacology, Ghent University, Ghent, Belgium
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27
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Shimatani H, Kojima Y, Kadowaki M, Nakagawa T, Fujii H, Nakajima Y, Takaki M. A 5-HT4 agonist mosapride enhances rectorectal and rectoanal reflexes in guinea pigs. Am J Physiol Gastrointest Liver Physiol 2003; 285:G389-95. [PMID: 12724131 DOI: 10.1152/ajpgi.00085.2003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The rectal distension-evoked reflex rectal (R-R) contractions and internal anal sphincter (R-IAS) relaxations in guinea pigs were generated through the extrinsic sacral excitatory nerve pathway (pelvic nerves) and the intrinsic cholinergic excitatory and nitrergic inhibitory nerve pathways. The aim of the present study was to evaluate whether a prokinetic benzamide, mosapride, enhances the R-R and R-IAS reflexes mediated via 5-HT4 receptors in the guinea pig. The mechanical activities of the R and IAS were recorded with a balloon connected to a pressure transducer and a strain gauge force transducer in the anesthetized guinea pig with intact spinal-intestinal pathways. Gradual and sustained rectal distension evoked R-R contractions and synchronous R-IAS relaxations. Mosapride (0.1-1.0 mg/kg i.v.) dose-dependently enhanced both R-R and R-IAS reflex responses. Reflex indexes for R-R and R-IAS maximally increased from 1.0 (control) to 1.92 and 1.88, respectively. A specific 5-HT4 receptor antagonist, GR 113808 (1.0 mg/kg i.v.), antagonized the enhancement of the R-R and R-IAS reflexes induced by mosapride 1.0 mg/kg i.v. The present results indicate that mosapride enhanced the R-R and R-IAS reflexes mediated through 5-HT4 receptors.
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Affiliation(s)
- Hidehiko Shimatani
- Dept. of Physiology II, Nara Medical Univ., 840 Shijo-cho, Kashihara, Nara 634-8521, Japan
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Tsubouchi T, Saito T, Mizutani F, Yamauchi T, Iwanaga Y. Stimulatory action of itopride hydrochloride on colonic motor activity in vitro and in vivo. J Pharmacol Exp Ther 2003; 306:787-93. [PMID: 12724347 DOI: 10.1124/jpet.102.048603] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
We investigated the effects of itopride hydrochloride (itopride, N-[4-[2-(dimethylamino)ethoxy]benzyl]-3,4-dimethoxybenzamide hydrochloride), a gastroprokinetic agent, on the colonic motor activity in vitro and in vivo, in comparison with benzamides, cisapride hydrate (cisapride), and mosapride citrate (mosapride). Itopride stimulated both peristaltic and segmental motility induced by applying intraluminal pressure to the isolated guinea pig colon. Although cisapride and mosapride enhanced the segmental motility, they markedly reduced the peristaltic motility. In conscious dogs with implanted strain gauge force transducers, itopride stimulated contractile activity in the gastrointestinal tract from the stomach to the colon. Cisapride stimulated contractile activity in the gastric antrum, ileum, and ascending colon. Mosapride stimulated contractile activity only in the gastric antrum and ileum. In guinea pigs and rats, itopride accelerated colonic luminal transit. On the other hand, cisapride and mosapride failed to enhance colonic transit. These results demonstrate that itopride has a stimulatory action on colonic peristalsis, propelling colonic luminal contents, different from that of cisapride and mosapride. Therefore, itopride may be a useful drug for the treatment of functional bowel disorders such as functional constipation.
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29
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Affiliation(s)
- Michel Langlois
- CNRS-BIOCIS (UPRES A 8076), INSERM U-446, Institut de Signalisation et Innovation Thérapeutique (IFR-ISIT), Faculté de Pharmacie, Université de Paris-Sud, 92296 Châtenay-Malabry, France.
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Inui A, Yoshikawa T, Nagai R, Yoshida N, Ito T. Effects of mosapride citrate, a 5-HT4 receptor agonist, on colonic motility in conscious guinea pigs. JAPANESE JOURNAL OF PHARMACOLOGY 2002; 90:313-20. [PMID: 12501007 DOI: 10.1254/jjp.90.313] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
It is known that 5-HT(4) receptors in the colon of guinea pigs show a distribution similar to that in humans. Thus, we examined the effects of mosapride citrate (mosapride) and cisapride, two 5-HT(4)-receptor agonists, on colonic motility in conscious guinea pigs implanted with force transducers. Mosapride and cisapride administered intragastrically at doses of 3 - 30 mg/kg significantly enhanced the colonic motility. The enhancing effect of mosapride was antagonized by atropine or GR113808, a 5-HT(4)-receptor antagonist, but not by methysergide, a 5-HT(1)- and 5-HT(2)-receptor antagonist; ondansetron, a 5-HT(3)-receptor antagonist; or CP-99994, a tachykinin NK(1)-receptor antagonist. In vitro receptor autoradiography showed that mosapride and cisapride inhibit the specific binding of [(125)I]-SB207710, a selective radioligand of 5-HT(4) receptors, in the colon of guinea pigs. These results suggest that mosapride enhances colonic motility through the 5-HT(4)-receptor activation in guinea pigs and may be useful for treating constipation in patients with colonic motility dysfunction.
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Affiliation(s)
- Atsuko Inui
- Department of Safety Pharmacology, Developmental Research Laboratories, Dainippon Pharmaceutical Co., Ltd., Suita, Osaka, Japan
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31
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Kadowaki M, Wang XO, Shimatani H, Yoneda S, Takaki M. 5-HT4 receptor enhances the propulsive power of the peristaltic reflex in the rat distal colon. Auton Neurosci 2002; 99:62-5. [PMID: 12171259 DOI: 10.1016/s1566-0702(02)00063-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The present study was designed to investigate the nature of the 5-HT4 receptors affecting the peristaltic reflex in the isolated rat distal colon. A single peristaltic reflex was evoked by infusing Tyrode solution into the lumen of the isolated segment using our modified Trendelenburg's method under an isovolumic condition. A 5-HT4 receptor agonist, mosapride (10 nM), did not affect the threshold pressure and the propagation distance of the reflex contraction, but significantly increased the developed pressure (maximum pressure - threshold pressure) from 19.1 +/- 11.8 cm H2O in the control to 26.8 +/- 13.0 cm H2O (n = 8, P<0.05) without affecting the resting muscle tone in the distal colon. The present result suggests that stimulation of 5-HT4 receptor enhances the propulsive power to move the luminal contents in the rat distal colon.
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MESH Headings
- Animals
- Benzamides/pharmacology
- Colon/innervation
- Colon/physiology
- Dose-Response Relationship, Drug
- Enteric Nervous System/cytology
- Enteric Nervous System/drug effects
- Enteric Nervous System/metabolism
- Male
- Morpholines/pharmacology
- Muscle Contraction/drug effects
- Muscle Contraction/physiology
- Muscle Tonus/drug effects
- Muscle Tonus/physiology
- Muscle, Smooth/drug effects
- Muscle, Smooth/innervation
- Muscle, Smooth/physiology
- Neurons/cytology
- Neurons/drug effects
- Neurons/metabolism
- Peristalsis/drug effects
- Peristalsis/physiology
- Pressure
- Rats
- Rats, Wistar
- Receptors, Serotonin/drug effects
- Receptors, Serotonin/metabolism
- Receptors, Serotonin, 5-HT4
- Reflex, Stretch/drug effects
- Reflex, Stretch/physiology
- Serotonin/metabolism
- Serotonin Receptor Agonists/pharmacology
- Up-Regulation/drug effects
- Up-Regulation/physiology
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Affiliation(s)
- Makoto Kadowaki
- Department of Physiology II, Nara Medical University, Kashihara, Japan.
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32
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Fiorica-Howells E, Hen R, Gingrich J, Li Z, Gershon MD. 5-HT(2A) receptors: location and functional analysis in intestines of wild-type and 5-HT(2A) knockout mice. Am J Physiol Gastrointest Liver Physiol 2002; 282:G877-93. [PMID: 11960784 DOI: 10.1152/ajpgi.00435.2001] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The distribution and function of the 5-hydroxytryptamine (5-HT(2A)) receptor were investigated in the intestines of wild-type (5-HT(2A) +/+) and knockout (5-HT(2A) -/-) mice. In 5-HT(2A) +/+ mice, rats, and guinea pigs, 5-HT(2A) receptor immunoreactivity was found on circular and longitudinal smooth muscle cells, neurons, enterocytes, and Paneth cells. Muscular 5-HT(2A) receptors were concentrated in caveolae; neuronal 5-HT(2A) receptors were found intracellularly and on the plasma membranes of nerve cell bodies and axons. Neuronal 5-HT(2A) immunoreactivity was detected as early as E14 in ganglia, intravillus nerves, and the deep muscle plexus. The 5-HT(2A) -/- colon did not express 5-HT(2A) receptors and did not contract in response to exogenous 5-HT. 5-HT(2A) -/- enterocytes were smaller, Paneth cells fewer, and muscle layers thinner (and showed degeneration) compared with those of 5-HT(2A) +/+ littermates. The 5-HT(2A) receptor may thus be required for the maintenance and/or development of enteric neuroeffectors and other enteric functions, although gastrointestinal and colonic transit times in 5-HT(2A) -/- and +/+ mice did not differ significantly.
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MESH Headings
- Animals
- Enterocytes/chemistry
- Enterocytes/pathology
- Enterocytes/ultrastructure
- Female
- Fetus/cytology
- Gastric Emptying/physiology
- Gastrointestinal Motility/physiology
- Immunohistochemistry
- Intestines/chemistry
- Intestines/innervation
- Intestines/pathology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microscopy, Immunoelectron
- Muscle, Smooth/chemistry
- Muscle, Smooth/innervation
- Muscle, Smooth/pathology
- Myenteric Plexus/chemistry
- Myenteric Plexus/ultrastructure
- Paneth Cells/chemistry
- Paneth Cells/pathology
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT2A
- Receptors, Serotonin/analysis
- Receptors, Serotonin/genetics
- Receptors, Serotonin/metabolism
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Affiliation(s)
- Elena Fiorica-Howells
- Department of Anatomy and Cell Biology, Columbia University, College of Physicians and Surgeons, New York, New York 10032, USA.
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Belohlávková S, Simák J, Kokesová A, Hnilicková O, Hampl V. Fenfluramine-induced pulmonary vasoconstriction: role of serotonin receptors and potassium channels. J Appl Physiol (1985) 2001; 91:755-61. [PMID: 11457791 DOI: 10.1152/jappl.2001.91.2.755] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The anorexic agent fenfluramine considerably increases the risk of primary pulmonary hypertension. The mechanism of this effect is unknown. The appetite-reducing action of fenfluramine is mediated by its interaction with the metabolism of serotonin [5-hydroxytryptamine (5-HT)] in the brain. We tested the hypothesis that the pulmonary vasoconstrictive action of fenfluramine is at least in part mediated by 5-HT receptor activation. In addition, we sought to determine whether pharmacological reduction of voltage-gated potassium (K(V)) channel activity would potentiate the pulmonary vascular reactivity to fenfluramine. Using isolated rat lungs perfused with Krebs-albumin solution, we compared the inhibitory effect of ritanserin, an antagonist of 5-HT(2) receptors, on fenfluramine- and 5-HT-induced vasoconstriction. Both 5-HT (10(-5) mol/l) and fenfluramine (5 x 10(-4) mol/l) caused significant increases in perfusion pressure. Ritanserin at a dose (10(-7) mol/l) sufficient to inhibit >80% of the response to 5-HT reduced the response to fenfluramine by approximately 50%. A higher ritanserin dose (10(-5) mol/l) completely abolished the responses to 5-HT but had no more inhibitory effect on the responses to fenfluramine. A pharmacological blockade of K(V) channels by 4-aminopyridine (3 x 10(-3) mol/l) markedly potentiated the pulmonary vasoconstrictor response to fenfluramine but was without effect on the reactivity to 5-HT. These data indicate that the pulmonary vasoconstrictor response to fenfluramine is partly mediated by 5-HT receptors. Furthermore, the pulmonary vasoconstrictor potency of fenfluramine is elevated when the K(V)-channel activity is low. This finding suggests that preexisting K(V)-channel insufficiency may predispose some patients to the development of pulmonary hypertension during fenfluramine treatment.
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Affiliation(s)
- S Belohlávková
- Department of Pathophysiology, Charles University First Medical School, Prague 128 53, Czech Republic
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34
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Affiliation(s)
- R Warth
- Physiologisches Institut, Abt. II, Freiburg, Germany
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