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Almeida PP, Brito ML, Thomasi B, Mafra D, Fouque D, Knauf C, Tavares-Gomes AL, Stockler-Pinto MB. Is the enteric nervous system a lost piece of the gut-kidney axis puzzle linked to chronic kidney disease? Life Sci 2024; 351:122793. [PMID: 38848938 DOI: 10.1016/j.lfs.2024.122793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 05/20/2024] [Accepted: 06/04/2024] [Indexed: 06/09/2024]
Abstract
The enteric nervous system (ENS) regulates numerous functional and immunological attributes of the gastrointestinal tract. Alterations in ENS cell function have been linked to intestinal outcomes in various metabolic, intestinal, and neurological disorders. Chronic kidney disease (CKD) is associated with a challenging intestinal environment due to gut dysbiosis, which further affects patient quality of life. Although the gut-related repercussions of CKD have been thoroughly investigated, the involvement of the ENS in this puzzle remains unclear. ENS cell dysfunction, such as glial reactivity and alterations in cholinergic signaling in the small intestine and colon, in CKD are associated with a wide range of intestinal pathways and responses in affected patients. This review discusses how the ENS is affected in CKD and how it is involved in gut-related outcomes, including intestinal permeability, inflammation, oxidative stress, and dysmotility.
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Affiliation(s)
| | - Michele Lima Brito
- Pathology Post Graduate Program, Fluminense Federal University (UFF), Niterói, RJ, Brazil
| | - Beatriz Thomasi
- Department of Physiology, Neuroscience Program, Michigan State University (MSU), East Lansing, MI, USA
| | - Denise Mafra
- Graduate Program in Biological Sciences - Physiology, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
| | - Denis Fouque
- Department of Nephrology, Centre Hopitalier Lyon Sud, INSERM 1060, CENS, Université de Lyon, France
| | - Claude Knauf
- INSERM U1220 Institut de Recherche en Santé Digestive, CHU Purpan, Université Toulouse III Paul Sabatier Toulouse, Toulouse, France
| | - Ana Lúcia Tavares-Gomes
- Neurosciences Post Graduate Program, Fluminense Federal University (UFF), Niterói, RJ, Brazil
| | - Milena Barcza Stockler-Pinto
- Pathology Post Graduate Program, Fluminense Federal University (UFF), Niterói, RJ, Brazil; INSERM U1220 Institut de Recherche en Santé Digestive, CHU Purpan, Université Toulouse III Paul Sabatier Toulouse, Toulouse, France
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2
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Gonzales J, Dharshika C, Mazhar K, Morales-Soto W, McClain JL, Moeser AJ, Nault R, Price TJ, Gulbransen BD. Early life adversity promotes gastrointestinal dysfunction through a sex-dependent phenotypic switch in enteric glia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.31.596805. [PMID: 38895433 PMCID: PMC11185517 DOI: 10.1101/2024.05.31.596805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Irritable bowel syndrome and related disorders of gut-brain interaction (DGBI) are common and exhibit a complex, poorly understood etiology that manifests as abnormal gut motility and pain. Risk factors such as biological sex, stressors during critical periods, and inflammation are thought to influence DGBI vulnerability by reprogramming gut-brain circuits, but the specific cells affected are unclear. Here, we used a model of early life stress to understand cellular mechanisms in the gut that produce DGBIs. Our findings identify enteric glia as a key cellular substrate in which stress and biological sex converge to dictate DGBI susceptibility. Enteric glia exhibit sexual dimorphism in genes and functions related to cellular communication, inflammation, and disease susceptibility. Experiencing early life stress has sex-specific effects on enteric glia that cause a phenotypic switch in male glia toward a phenotype normally observed in females. This phenotypic transformation is followed by physiological changes in the gut, mirroring those observed in DGBI in humans. These effects are mediated, in part, by alterations to glial prostaglandin and endocannabinoid signaling. Together, these data identify enteric glia as a cellular integration site through which DGBI risk factors produce changes in gut physiology and suggest that manipulating glial signaling may represent an attractive target for sex-specific therapeutic strategies in DGBIs.
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Morales-Soto W, Gonzales J, Jackson WF, Gulbransen BD. Enteric glia promote visceral hypersensitivity during inflammation through intercellular signaling with gut nociceptors. Sci Signal 2023; 16:eadg1668. [PMID: 37988454 PMCID: PMC10733972 DOI: 10.1126/scisignal.adg1668] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 10/17/2023] [Indexed: 11/23/2023]
Abstract
Inflammation in the intestines causes abdominal pain that is challenging to manage. The terminals of sensory neurons innervating the gut are surrounded by glia. Here, using a mouse model of acute colitis, we found that enteric glia contribute to visceral pain by secreting factors that sensitized sensory nerves innervating the gut in response to inflammation. Acute colitis induced a transient increase in the production of proinflammatory cytokines in the intestines of male and female mice. Of these, IL-1β was produced in part by glia and augmented the opening of the intercellular communication hemichannel connexin-43 in glia, which made normally innocuous stimuli painful in female mice. Chemogenetic glial activation paired with calcium imaging in nerve terminals demonstrated that glia sensitized gut-innervating nociceptors only under inflammatory conditions. This inflammatory, glial-driven visceral hypersensitivity involved an increased abundance of the enzyme COX-2 in glia, resulting in greater production and release of prostaglandin E2 that activated EP4 receptors on sensory nerve terminals. Blocking EP4 receptors reduced nociceptor sensitivity in response to glial stimulation in tissue samples from colitis-model mice, and impairing glial connexin-43 reduced visceral hypersensitivity induced by IL-1β in female mice. The findings suggest that therapies targeting enteric glial-neuron signaling might alleviate visceral pain caused by inflammatory disorders.
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Affiliation(s)
- Wilmarie Morales-Soto
- Department of Physiology, Neuroscience Program, Michigan State University, East Lansing, MI, 48824 USA
| | - Jacques Gonzales
- Department of Physiology, Neuroscience Program, Michigan State University, East Lansing, MI, 48824 USA
| | - William F. Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, 48824 USA
| | - Brian D. Gulbransen
- Department of Physiology, Neuroscience Program, Michigan State University, East Lansing, MI, 48824 USA
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4
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Sharkey KA, Mawe GM. The enteric nervous system. Physiol Rev 2023; 103:1487-1564. [PMID: 36521049 PMCID: PMC9970663 DOI: 10.1152/physrev.00018.2022] [Citation(s) in RCA: 70] [Impact Index Per Article: 70.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 12/12/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022] Open
Abstract
Of all the organ systems in the body, the gastrointestinal tract is the most complicated in terms of the numbers of structures involved, each with different functions, and the numbers and types of signaling molecules utilized. The digestion of food and absorption of nutrients, electrolytes, and water occurs in a hostile luminal environment that contains a large and diverse microbiota. At the core of regulatory control of the digestive and defensive functions of the gastrointestinal tract is the enteric nervous system (ENS), a complex system of neurons and glia in the gut wall. In this review, we discuss 1) the intrinsic neural control of gut functions involved in digestion and 2) how the ENS interacts with the immune system, gut microbiota, and epithelium to maintain mucosal defense and barrier function. We highlight developments that have revolutionized our understanding of the physiology and pathophysiology of enteric neural control. These include a new understanding of the molecular architecture of the ENS, the organization and function of enteric motor circuits, and the roles of enteric glia. We explore the transduction of luminal stimuli by enteroendocrine cells, the regulation of intestinal barrier function by enteric neurons and glia, local immune control by the ENS, and the role of the gut microbiota in regulating the structure and function of the ENS. Multifunctional enteric neurons work together with enteric glial cells, macrophages, interstitial cells, and enteroendocrine cells integrating an array of signals to initiate outputs that are precisely regulated in space and time to control digestion and intestinal homeostasis.
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Affiliation(s)
- Keith A Sharkey
- Hotchkiss Brain Institute and Snyder Institute for Chronic Diseases, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Gary M Mawe
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington, Vermont
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5
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Mantel M, Derkinderen P, Bach-Ngohou K, Neunlist M, Rolli-Derkinderen M. Crosstalk between omega-6 oxylipins and the enteric nervous system: Implications for gut disorders? Front Med (Lausanne) 2023; 10:1083351. [PMID: 37056732 PMCID: PMC10086145 DOI: 10.3389/fmed.2023.1083351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 03/03/2023] [Indexed: 03/30/2023] Open
Abstract
The enteric nervous system (ENS) continues to dazzle scientists with its ability to integrate signals, from the outside as well as from the host, to accurately regulate digestive functions. Composed of neurons and enteric glial cells, the ENS interplays with numerous neighboring cells through the reception and/or the production of several types of mediators. In particular, ENS can produce and release n-6 oxylipins. These lipid mediators, derived from arachidonic acid, play a major role in inflammatory and allergic processes, but can also regulate immune and nervous system functions. As such, the study of these n-6 oxylipins on the digestive functions, their cross talk with the ENS and their implication in pathophysiological processes is in full expansion and will be discussed in this review.
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Affiliation(s)
- Marine Mantel
- Nantes Université, Inserm, The Enteric Nervous System in Gut and Brain Disorders, Nantes, France
| | - Pascal Derkinderen
- CHU Nantes, Inserm, Nantes Université, The Enteric Nervous System in Gut and Brain Disorders, Nantes, France
| | - Kalyane Bach-Ngohou
- CHU Nantes, Inserm, Nantes Université, The Enteric Nervous System in Gut and Brain Disorders, Nantes, France
| | - Michel Neunlist
- Nantes Université, Inserm, The Enteric Nervous System in Gut and Brain Disorders, Nantes, France
| | - Malvyne Rolli-Derkinderen
- Nantes Université, Inserm, The Enteric Nervous System in Gut and Brain Disorders, Nantes, France
- *Correspondence: Malvyne Rolli-Derkinderen,
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Almeida PP, Valdetaro L, Thomasi BBDM, Stockler-Pinto MB, Tavares-Gomes AL. High-fat diets on the enteric nervous system: Possible interactions and mechanisms underlying dysmotility. Obes Rev 2022; 23:e13404. [PMID: 34873814 DOI: 10.1111/obr.13404] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/25/2021] [Accepted: 11/15/2021] [Indexed: 01/09/2023]
Abstract
Obesity is a chronic disease that affects various physiological systems. Among them, the gastrointestinal tract appears to be a main target of this disease. High-fat diet (HFD) animal models can help recapitulate the classic signs of obesity and present a series of gastrointestinal alterations, mainly dysmotility. Because intestinal motility is governed by the enteric nervous system (ENS), enteric neurons, and glial cells have been studied in HFD models. Given the importance of the ENS in general gut physiology, this review aims to discuss the relationship between HFD-induced neuroplasticity and gut dysmotility observed in experimental models. Furthermore, we highlight components of the gut environment that might influence enteric neuroplasticity, including gut microbiota, enteric glio-epithelial unit, serotonin release, immune cells, and disturbances such as inflammation and oxidative stress.
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Affiliation(s)
| | - Luisa Valdetaro
- Postgraduate Program in Neurosciences, Fluminense Federal University, Niterói, Brazil
| | | | - Milena Barcza Stockler-Pinto
- Postgraduate Program in Cardiovascular Sciences, Fluminense Federal University, Niterói, Brazil.,Postgraduate Program in Nutrition Sciences, Fluminense Federal University, Niterói, Brazil
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Li ZS, Hung LY, Margolis KG, Ambron RT, Sung YJ, Gershon MD. The α isoform of cGMP-dependent protein kinase 1 (PKG1α) is expressed and functionally important in intrinsic primary afferent neurons of the guinea pig enteric nervous system. Neurogastroenterol Motil 2021; 33:e14100. [PMID: 33655600 PMCID: PMC8681866 DOI: 10.1111/nmo.14100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 01/18/2021] [Accepted: 01/26/2021] [Indexed: 12/15/2022]
Abstract
BACKGROUND Intrinsic primary afferent neurons (IPANs) enable the gut to manifest reflexes in the absence of CNS input. PKG1α is selectively expressed in a subset of neurons in dorsal root ganglia (DRG) and has been linked to nociception and long-term hyperexcitability. METHODS We used immunoblotting, immunocytochemistry, and in vitro assays of IPAN-dependent enteric functions to test hypotheses that subsets of primary neurons of the ENS and DRG share a reliance on PKG1α expression. KEY RESULTS PKG1α immunoreactivity was demonstrated in immunoblots from isolated myenteric ganglia. PKG1α, but not PKG1β, immunoreactivity, was coincident with that of neuronal markers (HuC/D; β3-tubulin) in both enteric plexuses. PKG1α immunoreactivity also co-localized with the immunoreactivities of the IPAN markers, calbindin (100%; myenteric plexus) and cytoplasmic NeuN (98 ± 1% submucosal plexus). CGRP-immunoreactive DRG neurons, identified as visceral afferents by retrograde transport, were PKG1α-immunoreactive. We used intraluminal cholera toxin to determine whether PKG1α was necessary to enable stimulation of the mucosa to activate Fos in enteric neurons. Tetrodotoxin (1.0 µM), low Ca2+ /high Mg2+ media, and the PKG inhibitor, N46 (100 µM), all inhibited Fos activation in myenteric neurons. N46 also concentration dependently inhibited peristaltic reflexes in isolated preparations of distal colon (IC50 = 83.3 ± 1.3 µM). CONCLUSIONS & INFERENCES These data suggest that PKG1α is present and functionally important in IPANs and visceral afferent nociceptive neurons.
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Affiliation(s)
- Zhi S. Li
- Departments of Pathology & Cell Biology, Columbia University, New York, NY, USA
| | - Lin Y. Hung
- Departments of Pediatrics, Columbia University, New York, NY, USA
| | - Kara G. Margolis
- Departments of Pediatrics, Columbia University, New York, NY, USA
| | - Richard T. Ambron
- Departments of Pathology & Cell Biology, Columbia University, New York, NY, USA
| | - Ying J. Sung
- Departments of Basic Science, The Commonwealth Medical College, Scranton, PA, USA
| | - Michael D. Gershon
- Departments of Pathology & Cell Biology, Columbia University, New York, NY, USA
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8
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Ma J, Wang FY, Xu L, Wang YF, Tang XD. Mechanism of mast cell-mediated COX2-PGE2-Eps signaling pathway in visceral hypersensitivity in irritable bowel syndrome. Shijie Huaren Xiaohua Zazhi 2021; 29:306-311. [DOI: 10.11569/wcjd.v29.i6.306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder (FGID) whose pathophysiological mechanism is complex, involving genetic factors, psychosocial factors, low-grade mucosal inflammation, changes in the intestinal barrier, bacterial flora disorder, neuroimmune abnormalities, and high visceral sensitivity. In recent years, the mechanism of visceral hypersensitivity in IBS has become a hot research topic. Mast cells (MCs) are a group of immune cells that are distributed in the central nervous system and digestive system. The COX2-PGE2-Eps signaling pathway plays a major role in the visceral hypersensitivity in IBS, from peripheral sensitization to central sensitization, which provides a new idea for further clarifying the pathological mechanism of IBS.
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Affiliation(s)
- Jing Ma
- Graduate School of China Academy of Chinese Medical Sciences, Beijing 100000, China
| | - Feng-Yun Wang
- Department of Spleen and Stomach, Xiyuan Hospital of China Academy of Chinese Medical Sciences, Beijing 100091, China
| | - Lin Xu
- Graduate School of China Academy of Chinese Medical Sciences, Beijing 100000, China
| | - Yi-Fan Wang
- Peking University Traditional Chinese Medicine Clinical Medical School, Beijing 100091, China
| | - Xu-Dong Tang
- China Academy of Chinese Medical Sciences, Beijing 100091, China
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9
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Fung C, Vanden Berghe P. Functional circuits and signal processing in the enteric nervous system. Cell Mol Life Sci 2020; 77:4505-4522. [PMID: 32424438 PMCID: PMC7599184 DOI: 10.1007/s00018-020-03543-6] [Citation(s) in RCA: 103] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/13/2020] [Accepted: 04/27/2020] [Indexed: 02/06/2023]
Abstract
The enteric nervous system (ENS) is an extensive network comprising millions of neurons and glial cells contained within the wall of the gastrointestinal tract. The major functions of the ENS that have been most studied include the regulation of local gut motility, secretion, and blood flow. Other areas that have been gaining increased attention include its interaction with the immune system, with the gut microbiota and its involvement in the gut-brain axis, and neuro-epithelial interactions. Thus, the enteric circuitry plays a central role in intestinal homeostasis, and this becomes particularly evident when there are faults in its wiring such as in neurodevelopmental or neurodegenerative disorders. In this review, we first focus on the current knowledge on the cellular composition of enteric circuits. We then further discuss how enteric circuits detect and process external information, how these signals may be modulated by physiological and pathophysiological factors, and finally, how outputs are generated for integrated gut function.
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Affiliation(s)
- Candice Fung
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Pieter Vanden Berghe
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium.
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10
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Metin M, Altun A, Köylüoğlu G. The effect of probiotics on ıntestinal motility in an experimental short bowel model. Acta Cir Bras 2020; 35:e202000804. [PMID: 32901681 PMCID: PMC7478466 DOI: 10.1590/s0102-865020200080000004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 07/24/2020] [Indexed: 12/23/2022] Open
Abstract
PURPOSE To investigate the effect of probiotics on spontaneous contractions of smooth muscle isolated from jejunum and ileum of rat model. METHODS Four rat groups were created (n=8, in each) including control (Group 1), control+probiotic (Group 2), short bowel (Group 3), and short bowel+probiotic (Group 4). Groups 1 and 2 underwent sham operation, Groups 3 and 4 underwent massive bowel resection. Bifidobacterium Lactis was administered in Groups 2 and 4 daily (P.O.) for three weeks. On postoperative week 3, rats were sacrificed, and jejunum and ileum smooth muscle were isolated for organ bath. Muscle contraction changes were analyzed before and after addition of antagonists. RESULTS Short bowel group exhibited increased amplitude and frequency of spontaneous contractions. The addition of probiotics significantly decreased enhanced amplitude and frequency of bowel contraction in short bowel group and returned to control values. L-NNA increased amplitude and frequency of contractions in all groups. While indomethacin and nimesulide increased the amplitude in all groups, the frequency was only increased in jejunum. Hexamethonium and tetrodotoxin did not change the contraction characteristics in all groups. CONCLUSION We suggest that early use of probiotics may significantly regulate bowel motility, and accordingly improve absorption of nutrients in short bowel syndrome.
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Affiliation(s)
- Mehmet Metin
- Cumhuriyet University, Turkey; Hitit University Erol Olçok Training and Research Hospital, Turkey
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11
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Spear ET, Mawe GM. Enteric neuroplasticity and dysmotility in inflammatory disease: key players and possible therapeutic targets. Am J Physiol Gastrointest Liver Physiol 2019; 317:G853-G861. [PMID: 31604034 PMCID: PMC6962496 DOI: 10.1152/ajpgi.00206.2019] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Intestinal functions, including motility and secretion, are locally controlled by enteric neural networks housed within the wall of the gut. The fidelity of these functions depends on the precision of intercellular signaling among cellular elements, including enteric neurons, epithelial cells, immune cells, and glia, all of which are vulnerable to disruptive influences during inflammatory events. This review article describes current knowledge regarding inflammation-induced neuroplasticity along key elements of enteric neural circuits, what is known about the causes of these changes, and possible therapeutic targets for protecting and/or repairing the integrity of intrinsic enteric neurotransmission. Changes that have been detected in response to inflammation include increased epithelial serotonin availability, hyperexcitability of intrinsic primary afferent neurons, facilitation of synaptic activity among enteric neurons, and attenuated purinergic neuromuscular transmission. Dysfunctional propulsive motility has been detected in models of colitis, where causes include the changes described above, and in models of multiple sclerosis and other autoimmune conditions, where autoantibodies are thought to mediate dysmotility. Other cells implicated in inflammation-induced neuroplasticity include muscularis macrophages and enteric glia. Targeted treatments that are discussed include 5-hydroxytryptamine receptor 4 agonists, cyclooxygenase inhibitors, antioxidants, B cell depletion therapy, and activation of anti-inflammatory pathways.
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Affiliation(s)
- Estelle T. Spear
- 1Division of Gastroenterology and Hepatology, Department of Medicine, School of Medicine, Stanford University, Stanford, California
| | - Gary M. Mawe
- 2Department of Neurological Sciences, The University of Vermont, Burlington, Vermont
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12
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Coates MD, Tekin I, Vrana KE, Mawe GM. Review article: the many potential roles of intestinal serotonin (5-hydroxytryptamine, 5-HT) signalling in inflammatory bowel disease. Aliment Pharmacol Ther 2017; 46:569-580. [PMID: 28737264 DOI: 10.1111/apt.14226] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Revised: 04/10/2017] [Accepted: 06/24/2017] [Indexed: 12/19/2022]
Abstract
BACKGROUND Serotonin (5-hydroxytryptamine, 5-HT) is an important mediator of every major gut-related function. Recent investigations also suggest that 5-HT can influence the development and severity of inflammation within the gut, particularly in the setting of inflammatory bowel disease (IBD). AIM To review the roles that the intestinal serotonin signalling system plays in gut function, with a specific focus on IBD. METHODS We reviewed manuscripts from 1952 to 2017 that investigated and discussed roles for 5-HT signalling in gastrointestinal function and IBD, as well as the influence of inflammation on 5-HT signalling elements within the gut. RESULTS Inflammation appears to affect every major element of intestinal 5-HT signalling, including 5-HT synthesis, release, receptor expression and reuptake capacity. Importantly, many studies (most utilising animal models) also demonstrate that modulation of selective serotonergic receptors (via agonism of 5-HT4 R and antagonism of 5-HT3 R) or 5-HT signal termination (via serotonin reuptake inhibitors) can alter the likelihood and severity of intestinal inflammation and/or its complicating symptoms. However, there are few human studies that have studied these relationships in a targeted manner. CONCLUSIONS Insights discussed in this review have strong potential to lead to new diagnostic and therapeutic tools to improve the management of IBD and other related disorders. Specifically, strategies that focus on modifying the activity of selective serotonin receptors and reuptake transporters in the gut could be effective for controlling disease activity and/or its associated symptoms. Further studies in humans are required, however, to more completely understand the pathophysiological mechanisms underlying the roles of 5-HT in this setting.
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Affiliation(s)
- M D Coates
- Department of Medicine, Division of Gastroenterology & Hepatology, Penn State Hershey Medical Center, Hershey, PA, USA
| | - I Tekin
- Neuroscience Institute, University of California at Santa Barbara, Santa Barbara, CA, USA
| | - K E Vrana
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA, USA
| | - G M Mawe
- Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, VT, USA
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13
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Spohn SN, Bianco F, Scott RB, Keenan CM, Linton AA, O’Neill CH, Bonora E, Dicay M, Lavoie B, Wilcox RL, MacNaughton WK, De Giorgio R, Sharkey KA, Mawe GM. Protective Actions of Epithelial 5-Hydroxytryptamine 4 Receptors in Normal and Inflamed Colon. Gastroenterology 2016; 151:933-944.e3. [PMID: 27480173 PMCID: PMC5159265 DOI: 10.1053/j.gastro.2016.07.032] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 06/16/2016] [Accepted: 07/06/2016] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS The 5-hydroxytryptamine receptor 4 (5-HT4R or HTR4) is expressed in the colonic epithelium but little is known about its functions there. We examined whether activation of colonic epithelial 5-HT4R protects colons of mice from inflammation. METHODS The 5-HT4R agonist tegaserod (1 mg/kg), the 5-HT4R antagonist GR113808 (1 mg/kg), or vehicle (control) were delivered by enema to wild-type or 5-HT4R knockout mice at the onset of, or during, active colitis, induced by administration of dextran sodium sulfate or trinitrobenzene sulfonic acid. Inflammation was measured using the colitis disease activity index and by histologic analysis of intestinal tissues. Epithelial proliferation, wound healing, and resistance to oxidative stress-induced apoptosis were assessed, as was colonic motility. RESULTS Rectal administration of tegaserod reduced the severity of colitis compared with mice given vehicle, and accelerated recovery from active colitis. Rectal tegaserod did not improve colitis in 5-HT4R knockout mice, and intraperitoneally administered tegaserod did not protect wild-type mice from colitis. Tegaserod increased proliferation of crypt epithelial cells. Stimulation of 5-HT4R increased Caco-2 cell migration and reduced oxidative stress-induced apoptosis; these actions were blocked by co-administration of the 5-HT4R antagonist GR113808. In noninflamed colons of wild-type mice not receiving tegaserod, inhibition of 5-HT4Rs resulted in signs of colitis within 3 days. In these mice, epithelial proliferation decreased and bacterial translocation to the liver and spleen was detected. Daily administration of tegaserod increased motility in inflamed colons of guinea pigs and mice, whereas administration of GR113808 disrupted motility in animals without colitis. CONCLUSIONS 5-HT4R activation maintains motility in healthy colons of mice and guinea pigs, and reduces inflammation in colons of mice with colitis. Agonists might be developed as treatments for patients with inflammatory bowel diseases.
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Affiliation(s)
| | - Francesca Bianco
- Department of Veterinary Medical Sciences,Department of Medical and Surgical Sciences, University of Bologna, Italy
| | | | - Catherine M. Keenan
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada,Snyder Institute for Chronic Diseases, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | | | | | - Elena Bonora
- Department of Medical and Surgical Sciences, University of Bologna, Italy
| | - Michael Dicay
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Brigitte Lavoie
- Neurological Sciences, University of Vermont, Burlington, VT
| | | | - Wallace K. MacNaughton
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Roberto De Giorgio
- Department of Medical and Surgical Sciences, University of Bologna, Italy
| | - Keith A. Sharkey
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada,Snyder Institute for Chronic Diseases, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Gary M. Mawe
- Neurological Sciences, University of Vermont, Burlington, VT
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Margolis KG, Gershon MD. Enteric Neuronal Regulation of Intestinal Inflammation. Trends Neurosci 2016; 39:614-624. [PMID: 27450201 DOI: 10.1016/j.tins.2016.06.007] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 06/24/2016] [Accepted: 06/27/2016] [Indexed: 02/07/2023]
Abstract
Recent research has highlighted the importance of the two-way interaction between the nervous and immune systems. This interaction is particularly important in the bowel because of the unique properties of this organ. The lumen of the gut is lined by a very large but remarkably thin surface that separates the body from the enteric microbiome. Immune defenses against microbial invasion are thus well developed and neuroimmune interactions are important in regulating and integrating these defenses. Important concepts in the phylogeny of neuroimmunity, enteric neuronal and glial regulation of immunity, changes that occur in the enteric nervous system during inflammation, the fundamental role of serotonin (5-HT) in enteric neuroimmune mechanisms, and future perspectives are reviewed.
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Affiliation(s)
- Kara Gross Margolis
- Department of Pediatrics, Columbia University College of Physicians and Surgeons, 620 West 168th Street, New York, NY 10032, USA
| | - Michael D Gershon
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, 650 West 168th Street, New York, NY 10032, USA.
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The Intrinsic Reflex Circuitry of the Inflamed Colon. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 891:153-7. [DOI: 10.1007/978-3-319-27592-5_15] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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16
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LI HAIXIA, YIN JIEYUN, ZHANG ZHAOHUI, WINSTON JOHNH, SHI XUANZHENG, CHEN JIANDED. Auricular vagal nerve stimulation ameliorates burn-induced gastric dysmotility via sympathetic-COX-2 pathways in rats. Neurogastroenterol Motil 2016; 28:36-42. [PMID: 26486522 PMCID: PMC4688125 DOI: 10.1111/nmo.12693] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 08/29/2015] [Indexed: 12/13/2022]
Abstract
BACKGROUND Severe burn injury has been demonstrated to delay gastric emptying. The aim of this study was to investigate effects and cellular mechanisms of auricular electroacupuncture (AEA) at the acupoints innervated by the auricular branch of vagus nerve on burn-induced gastric dysmotility in rats. METHODS Propranolol (β-adrenoceptor antagonist) was injected intraperitoneally after the rats underwent burn injury. All experiments were performed 6 h following burn/sham burn injury. AEA was performed at bilateral auricular acupoints for 45 min. Electrocardiogram was recorded for 30 min. Plasma hormones were measured; cyclooxygenase (COX)-2 expressions in gastric tissue were measured using western blotting and real-time RT-PCR. KEY RESULTS (i) Burn injury delayed gastric emptying (p = 0.006) and AEA increased gastric emptying by 49% (p = 0.045). (ii) Burn injury evoked a significant elevation in plasma noradrenaline, which was suppressed by AEA. (iii) Burn injury significantly increased protein and mRNA expressions of COX-2 in gastric fundus and antrum. AEA suppressed burn-induced increase in protein expressions, but not mRNA expressions of COX-2. CONCLUSIONS & INFERENCES Burn injury delays gastric emptying by up-regulating COX-2 attributed to sympathetic overactivity. AEA improves burn-induced delay in gastric emptying, possibly mediated via the sympathetic-COX-2 pathway.
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Affiliation(s)
- HAIXIA LI
- Department of Internal Medicine, Division of Gastroenterology, University of Texas Medical Branch at Galveston, Texas,Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - JIEYUN YIN
- Department of Internal Medicine, Division of Gastroenterology, University of Texas Medical Branch at Galveston, Texas,Division of Gastroenterology and Hepatology, Johns Hopkins School of Medicine, Baltimore, MD 21224
| | - ZHAOHUI ZHANG
- Department of Internal Medicine, Division of Gastroenterology, University of Texas Medical Branch at Galveston, Texas
| | - JOHN H. WINSTON
- Department of Internal Medicine, Division of Gastroenterology, University of Texas Medical Branch at Galveston, Texas
| | - XUAN-ZHENG SHI
- Department of Internal Medicine, Division of Gastroenterology, University of Texas Medical Branch at Galveston, Texas
| | - JIANDE D.Z. CHEN
- Department of Internal Medicine, Division of Gastroenterology, University of Texas Medical Branch at Galveston, Texas,Division of Gastroenterology and Hepatology, Johns Hopkins School of Medicine, Baltimore, MD 21224
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Robinson AM, Miller S, Payne N, Boyd R, Sakkal S, Nurgali K. Neuroprotective Potential of Mesenchymal Stem Cell-Based Therapy in Acute Stages of TNBS-Induced Colitis in Guinea-Pigs. PLoS One 2015; 10:e0139023. [PMID: 26397368 PMCID: PMC4580595 DOI: 10.1371/journal.pone.0139023] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 09/07/2015] [Indexed: 12/13/2022] Open
Abstract
Background & Aims The therapeutic benefits of mesenchymal stem cells (MSCs), such as homing ability, multipotent differentiation capacity and secretion of soluble bioactive factors which exert neuroprotective, anti-inflammatory and immunomodulatory properties, have been attributed to attenuation of autoimmune, inflammatory and neurodegenerative disorders. In this study, we aimed to determine the earliest time point at which locally administered MSC-based therapies avert enteric neuronal loss and damage associated with intestinal inflammation in the guinea-pig model of colitis. Methods At 3 hours after induction of colitis by 2,4,6-trinitrobenzene-sulfonate (TNBS), guinea-pigs received either human bone marrow-derived MSCs, conditioned medium (CM), or unconditioned medium by enema into the colon. Colon tissues were collected 6, 24 and 72 hours after administration of TNBS. Effects on body weight, gross morphological damage, immune cell infiltration and myenteric neurons were evaluated. RT-PCR, flow cytometry and antibody array kit were used to identify neurotrophic and neuroprotective factors released by MSCs. Results MSC and CM treatments prevented body weight loss, reduced infiltration of leukocytes into the colon wall and the myenteric plexus, facilitated repair of damaged tissue and nerve fibers, averted myenteric neuronal loss, as well as changes in neuronal subpopulations. The neuroprotective effects of MSC and CM treatments were observed as early as 24 hours after induction of inflammation even though the inflammatory reaction at the level of the myenteric ganglia had not completely subsided. Substantial number of neurotrophic and neuroprotective factors released by MSCs was identified in their secretome. Conclusion MSC-based therapies applied at the acute stages of TNBS-induced colitis start exerting their neuroprotective effects towards enteric neurons by 24 hours post treatment. The neuroprotective efficacy of MSC-based therapies can be exerted independently to their anti-inflammatory effects.
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Affiliation(s)
- Ainsley M. Robinson
- Centre for Chronic Diseases, College of Health and Biomedicine, Victoria University, Melbourne, Australia
| | - Sarah Miller
- Centre for Chronic Diseases, College of Health and Biomedicine, Victoria University, Melbourne, Australia
| | - Natalie Payne
- Department of Anatomy and Neuroscience, Monash University, Melbourne, Australia
- Australian Regenerative Medicine Institute, Monash University, Melbourne, Australia
| | - Richard Boyd
- Department of Anatomy and Neuroscience, Monash University, Melbourne, Australia
| | - Samy Sakkal
- Centre for Chronic Diseases, College of Health and Biomedicine, Victoria University, Melbourne, Australia
| | - Kulmira Nurgali
- Centre for Chronic Diseases, College of Health and Biomedicine, Victoria University, Melbourne, Australia
- * E-mail:
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18
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Mawe GM. Colitis-induced neuroplasticity disrupts motility in the inflamed and post-inflamed colon. J Clin Invest 2015; 125:949-55. [PMID: 25729851 DOI: 10.1172/jci76306] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Effective colonic motility involves an intricate pattern of excitatory and inhibitory neuromuscular signals that arise from the enteric neural circuitry of the colon. Recent investigations have demonstrated that inflammation leads to a variety of changes in the physiological properties of the neurons in this circuitry, including hyperexcitability of neurons at the afferent end of the peristaltic reflex, synaptic facilitation, and attenuated inhibitory neuromuscular transmission. Furthermore, links have been established between these changes and disrupted motor activity in the colon, and we now know that some of these changes persist long after recovery from inflammation. It is highly likely that inflammation-induced neuroplasticity, which is not detectable by clinical diagnostics, contributes to disrupted motility in active and quiescent inflammatory bowel disease and in functional gastrointestinal disorders.
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Lin YM, Fu Y, Wu CC, Xu GY, Huang LY, Shi XZ. Colon distention induces persistent visceral hypersensitivity by mechanotranscription of pain mediators in colonic smooth muscle cells. Am J Physiol Gastrointest Liver Physiol 2015; 308:G434-41. [PMID: 25540231 PMCID: PMC4346753 DOI: 10.1152/ajpgi.00328.2014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Abdominal pain and distention are major complaints in irritable bowel syndrome. Abdominal distention is mainly attributed to intraluminal retention of gas or solid contents, which may cause mechanical stress to the gut wall. Visceral hypersensitivity (VHS) may account for abdominal pain. We sought to determine whether tonic colon distention causes persistent VHS and if so whether mechanical stress-induced expression (mechanotranscription) of pain mediators in colonic smooth muscle cells (SMCs) plays a role in VHS. Human colonic SMCs were isolated and stretched in vitro to investigate whether mechanical stress upregulates expression of the pain mediator cyclooxygenase-2 (COX-2). Rat colon was distended with a 5-cm-long balloon, and gene expression of COX-2, visceromotor response (VMR), and sensory neuron excitability were determined. Static stretch of colonic SMCs induced marked expression of COX-2 mRNA and protein in a force- and time-dependent manner. Subnoxious tonic distention of the distal colon at ∼30-40 mmHg for 20 or 40 min induced COX-2 expression and PGE2 production in colonic smooth muscle, but not in the mucosa layer. Lumen distention also increased VMR in a force- and time-dependent manner. The increase of VMR persisted for at least 3 days. Patch-clamp experiments showed that the excitability of colon projecting sensory neurons in the dorsal root ganglia was markedly augmented, 24 h after lumen distention. Administration of COX-2 inhibitor NS-398 partially but significantly attenuated distention-induced VHS. In conclusion, tonic lumen distention upregulates expression of COX-2 in colonic SMC, and COX-2 contributes to persistent VHS.
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Affiliation(s)
- You-Min Lin
- 1Division of Gastroenterology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas; and
| | - Yu Fu
- 1Division of Gastroenterology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas; and
| | - Chester C. Wu
- 1Division of Gastroenterology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas; and
| | - Guang-Yin Xu
- 1Division of Gastroenterology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas; and
| | - Li-Yen Huang
- 2Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas
| | - Xuan-Zheng Shi
- Division of Gastroenterology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas; and
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Experimental model of tympanic colic (acute abdomen) in chinchillas (Chinchilla lanigera). Lab Anim Res 2014; 30:136-41. [PMID: 25324875 PMCID: PMC4188833 DOI: 10.5625/lar.2014.30.3.136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 09/04/2014] [Accepted: 09/11/2014] [Indexed: 11/21/2022] Open
Abstract
Digestive disorders caused by sudden changes in diet or inappropriate diet are among the most common disorders of the digestive system. Cecal or intestinal tympany, one consequence of inappropriate diet, is characterized by the accumulation of gases, marked distension of the cecum and colon and the induction of inflammatory processes. To know the effects of intestinal tympany on the enteric plexuses, we developed a method of experimental tympanic colic (TC) in the Chinchilla lanigera. This species was used in view of its susceptibility to TC. TC was induced with a diet rich in alfalfa associated with grain overload for two weeks. Physical and clinical examination including the von Frey test confirmed the diagnosis. The chinchillas with acute abdomen were treated with 1% ketoprofen and resumption of a balanced diet. Necropsy and histopathological analysis showed tympany-induced alterations mainly in the cecum and colon. After treatment, the control conditions were restored. The TC protocol is proposed as an experimental approach designed to aid the study of the effects of acute intestinal inflammation and obstruction caused by an inappropriate diet.
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Abstract
The gastrointestinal tract is innervated by several distinct populations of neurons, whose cell bodies either reside within (intrinsic) or outside (extrinsic) the gastrointestinal wall. Normally, most individuals are unaware of the continuous, complicated functions of these neurons. However, for patients with gastrointestinal disorders, such as IBD and IBS, altered gastrointestinal motility, discomfort and pain are common, debilitating symptoms. Although bouts of intestinal inflammation underlie the symptoms associated with IBD, increasing preclinical and clinical evidence indicates that infection and inflammation are also key risk factors for the development of other gastrointestinal disorders. Notably, a strong correlation exists between prior exposure to gut infection and symptom occurrence in IBS. This Review discusses the evidence for neuroplasticity (structural, synaptic or intrinsic changes that alter neuronal function) affecting gastrointestinal function. Such changes are evident during inflammation and, in many cases, long after healing of the damaged tissues, when the nervous system fails to reset back to normal. Neuroplasticity within distinct populations of neurons has a fundamental role in the aberrant motility, secretion and sensation associated with common clinical gastrointestinal disorders. To find appropriate therapeutic treatments for these disorders, the extent and time course of neuroplasticity must be fully appreciated.
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22
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Lin YM, Li F, Shi XZ. Mechanical stress is a pro-inflammatory stimulus in the gut: in vitro, in vivo and ex vivo evidence. PLoS One 2014; 9:e106242. [PMID: 25180799 PMCID: PMC4152012 DOI: 10.1371/journal.pone.0106242] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 07/28/2014] [Indexed: 12/14/2022] Open
Abstract
Aims Inflammatory infiltrates and pro-inflammatory mediators are found increased in obstructive and functional bowel disorders, in which lumen distention is present. However, what caused the low level inflammation is not well known. We tested the hypothesis that lumen distention- associated mechanical stress may induce expression of specific inflammatory mediators in gut smooth muscle. Methods Static mechanical stretch (18% elongation) was applied in vitro in primary culture of rat colonic circular smooth muscle cells (RCCSMCs) with a Flexercell FX-4000 Tension Plus System. Mechanical distention in vivo was induced in rats with an obstruction band placed in the distal colon. Results In the primary culture of RCCSMCs, we found that static stretch significantly induced mRNA expression of iNOS, IL-6, and MCP-1 in 3 hours by 6.0(±1.4), 2.5(±0.5), and 2.2(±0.5) fold (n = 6∼8, p<0.05), respectively. However, gene expression of TNF-α, IL-1β, and IL-8 was not significantly affected by mechanical stretch. In the in vivo model of colon obstruction, we found that gene expression of iNOS, IL-6, and MCP-1 is also significantly increased in a time-dependent manner in the mechanically distended proximal segment, but not in the sham controls or distal segments. The conditioned medium from the muscle strips of the stretched proximal segment, but not the distal segment or control, significantly induced translocation and phosphorylation of NF-κB p65. This treatment further increased mRNA expression of inflammatory mediators in the naïve cells. However, treatment of the conditioned medium from the proximal segment with neutralizing antibody against rat IL-6 significantly attenuated the activation of NF-κB and gene expression of inflammatory mediators. Conclusions Our studies demonstrate that mechanical stress induces gene expression of inflammatory mediators i.e. iNOS, IL-6, and MCP-1 in colonic SMC. Further ex vivo study showed that mechanical stress functions as a pro-inflammatory stimulus in the gut.
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MESH Headings
- Animals
- Antibodies, Neutralizing/pharmacology
- Cells, Cultured
- Chemokines/genetics
- Chemokines/metabolism
- Colon/pathology
- Culture Media, Conditioned/pharmacology
- Gastrointestinal Tract/drug effects
- Gastrointestinal Tract/pathology
- Inflammation/pathology
- Inflammation Mediators/metabolism
- Intestinal Obstruction/pathology
- Male
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Myocytes, Smooth Muscle/pathology
- NF-kappa B/metabolism
- Nitric Oxide/metabolism
- Nitric Oxide Synthase Type II/genetics
- Nitric Oxide Synthase Type II/metabolism
- Phosphorylation/drug effects
- Protein Transport/drug effects
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats, Sprague-Dawley
- Stress, Mechanical
- Up-Regulation/drug effects
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Affiliation(s)
- You-Min Lin
- Division of Gastroenterology, Department of Internal Medicine, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Feng Li
- Division of Gastroenterology, Department of Internal Medicine, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Xuan-Zheng Shi
- Division of Gastroenterology, Department of Internal Medicine, The University of Texas Medical Branch, Galveston, Texas, United States of America
- * E-mail:
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Moynes DM, Lucas GH, Beyak MJ, Lomax AE. Effects of inflammation on the innervation of the colon. Toxicol Pathol 2013; 42:111-7. [PMID: 24159054 DOI: 10.1177/0192623313505929] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Inflammatory bowel diseases (IBD) such as ulcerative colitis and Crohn's disease lead to altered gastrointestinal (GI) function as a consequence of the effects of inflammation on the tissues that comprise the GI tract. Among these tissues are several types of neurons that detect the state of the GI tract, transmit pain, and regulate functions such as motility, secretion, and blood flow. This review article describes the structure and function of the enteric nervous system, which is embedded within the gut wall, the sympathetic motor innervation of the colon and the extrinsic afferent innervation of the colon, and considers the evidence that colitis alters these important sensory and motor systems. These alterations may contribute to the pain and altered bowel habits that accompany IBD.
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Affiliation(s)
- Derek M Moynes
- 1Department of Biomedical and Molecular Sciences, Gastrointestinal Diseases Research Unit, Queen's University, Kingston, Ontario, Canada
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Abdu FB. Neuronal activation and plasticity in Schistosoma mansoni infected mice. Saudi J Biol Sci 2013; 19:495-501. [PMID: 23961211 DOI: 10.1016/j.sjbs.2012.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Revised: 07/09/2012] [Accepted: 07/14/2012] [Indexed: 10/28/2022] Open
Abstract
Schistosomiasis leads to structural and functional changes which may result from unbalanced release of some inflammatory mediators. The aim of the study was to investigate the effect of intestinal parasitic infection on nitric oxide release and to evaluate the neural plasticity that leads to motility disturbance. Experiments were performed in Swiss mice 8- and 12-weeks following infection with Schistosoma mansoni compared to untreated controls. Jejunal motility was assessed using a Trendelenburg preparation to study aboral directed peristaltic pressure waves. Histological examination was used to determine the pathological characteristics of inflammation. Parasitic infection produces diffuse inflammatory infiltrate in both 8- and 12-weeks infected animals. Inflammation had significant effect on peristaltic pressure waves amplitude and intervals at 8-weeks compared to control; whereas, in 12-weeks post infection there was a significant decrease in peristaltic pressure waves amplitude and interval compared to 8- weeks and control. Nitric oxide synthase inhibitor (L-NAME 100 μM) induced a significant increase in amplitude and decrease in intervals in control, 8- and 12- weeks infected animals. In conclusion, parasitic infection leads to disturbance in the release of the inflammatory mediators. This study indicated the role of nitric oxide in developing granulomatous inflammation and participating in motility disturbance.
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Affiliation(s)
- Faiza B Abdu
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, P.O. Box 42699, Jeddah 21551, Saudi Arabia
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Heredia DJ, Grainger N, McCann CJ, Smith TK. Insights from a novel model of slow-transit constipation generated by partial outlet obstruction in the murine large intestine. Am J Physiol Gastrointest Liver Physiol 2012; 303:G1004-16. [PMID: 22961801 PMCID: PMC3517665 DOI: 10.1152/ajpgi.00238.2012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The mechanisms underlying slow-transit constipation (STC) are unclear. In 50% of patients with STC, some form of outlet obstruction has been reported; also an elongated colon has been linked to patients with STC. Our aims were 1) to develop a murine model of STC induced by partial outlet obstruction and 2) to determine whether this leads to colonic elongation and, consequently, activation of the inhibitory "occult reflex," which may contribute to STC in humans. Using a purse-string suture, we physically reduced the maximal anal sphincter opening in C57BL/6 mice. After 4 days, the mice were euthanized (acutely obstructed), the suture was removed (relieved), or the suture was removed and replaced repeatedly (chronically obstructed, over 24-31 days). In partially obstructed mice, we observed increased cyclooxygenase (COX)-2 levels in muscularis and mucosa, an elongated impacted large bowel, slowed transit, nonpropagating colonic migrating motor complexes (CMMCs), a lack of mucosal reflexes, a depolarized circular muscle with slow-wave activity due to a lack of spontaneous inhibitory junction potentials, muscle hypertrophy, and CMMCs in mucosa-free preparations. Elongation of the empty obstructed colon produced a pronounced occult reflex. Removal of the obstruction or addition of a COX-2 antagonist (in vitro and in vivo) restored membrane potential, spontaneous inhibitory junction potentials, CMMC propagation, and mucosal reflexes. We conclude that partial outlet obstruction increases COX-2 leading to a hyperexcitable colon. This hyperexcitability is largely due to suppression of only descending inhibitory nerve pathways by prostaglandins. The upregulation of motility is suppressed by the occult reflex activated by colonic elongation.
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Affiliation(s)
- Dante J. Heredia
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Nathan Grainger
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Conor J. McCann
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Terence K. Smith
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
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Curcuma longa extract exerts a myorelaxant effect on the ileum and colon in a mouse experimental colitis model, independent of the anti-inflammatory effect. PLoS One 2012; 7:e44650. [PMID: 22984538 PMCID: PMC3440350 DOI: 10.1371/journal.pone.0044650] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 08/06/2012] [Indexed: 12/19/2022] Open
Abstract
Background Curcuma has long been used as an anti-inflammatory agent in inflammatory bowel disease. Since gastrointestinal motility is impaired in inflammatory states, the aim of this work was to evaluate if Curcuma Longa had any effect on intestinal motility. Methods The biological activity of Curcuma extract was evaluated against Carbachol induced contraction in isolated mice intestine. Acute and chronic colitis were induced in Balb/c mice by Dextran Sulphate Sodium administration (5% and 2.5% respectively) and either Curcuma extract (200 mg/kg/day) or placebo was thereafter administered for 7 and 21 days respectively. Spontaneous contractions and the response to Carbachol and Atropine of ileum and colon were studied after colitis induction and Curcuma administration. Results Curcuma extract reduced the spontaneous contractions in the ileum and colon; the maximal response to Carbachol was inhibited in a non-competitive and reversible manner. Similar results were obtained in ileum and colon from Curcuma fed mice. DSS administration decreased the motility, mainly in the colon and Curcuma almost restored both the spontaneous contractions and the response to Carbachol after 14 days assumption, compared to standard diet, but a prolonged assumption of Curcuma decreased the spontaneous and Carbachol-induced contractions. Conclusions Curcuma extract has a direct and indirect myorelaxant effect on mouse ileum and colon, independent of the anti-inflammatory effect. The indirect effect is reversible and non-competitive with the cholinergic agent. These results suggest the use of curcuma extract as a spasmolytic agent.
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Lin YM, Li F, Shi XZ. Mechano-transcription of COX-2 is a common response to lumen dilation of the rat gastrointestinal tract. Neurogastroenterol Motil 2012; 24:670-7, e295-6. [PMID: 22489918 PMCID: PMC4183192 DOI: 10.1111/j.1365-2982.2012.01918.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND In obstructive bowel disorders (OBDs) such as achalasia, pyloric stenosis, and bowel obstruction, the lumen of the affected segments is markedly dilated and the motility function is significantly impaired. We tested the hypothesis that mechanical stress in lumen dilation leads to induction of cyclooxygenase-2 (COX-2) in smooth muscle throughout the gastrointestinal (GI) tract, contributing to motility dysfunction. METHODS Lumen dilation was induced in vivo with obstruction bands (12 × 3 mm) applied over the lower esophageal sphincter (LES), the pyloric sphincter, and the ileum in rats for 48 h. Mechanical stretch in vivo was also emulated by balloon distension of the distal colon. Direct stretch of muscle strips from the esophagus, gastric fundus, and ileum was mimicked in an in vitro tissue culture system. KEY RESULTS Partial obstruction in the LES, pylorus, and ileum significantly increased the expression of COX-2 mRNA and protein in the muscularis externae of the dilated segment oral to the occlusions, but not in the aboral segment. Direct stretch of the lumen in vivo or of muscle strips in vitro markedly induced COX-2 expression. The smooth muscle contractility was significantly suppressed in the balloon-distended segments. However, treatment with COX-2 inhibitor NS-398 restored the contractility. Furthermore, in vivo administration of NS-398 in gastric outlet obstruction significantly improved gastric emptying. CONCLUSIONS & INFERENCES Mechanical dilation of the gut lumen by occlusion or direct distension induces gene expression of COX-2 throughout the GI tract. Mechanical stress-induced COX-2 contributes to motility dysfunction in conditions with lumen dilation.
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Affiliation(s)
| | | | - Xuan-Zheng Shi
- Address requests for reprints to: Xuan-Zheng “Peter” Shi, Department of Internal Medicine, Division of Gastroenterology, University of Texas Medical Branch, 301 University Boulevard, Basic Science Building 4.106, Galveston, TX 77555-0655,
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Lin YM, Sarna SK, Shi XZ. Prophylactic and therapeutic benefits of COX-2 inhibitor on motility dysfunction in bowel obstruction: roles of PGE₂ and EP receptors. Am J Physiol Gastrointest Liver Physiol 2012; 302:G267-75. [PMID: 22038825 PMCID: PMC3341114 DOI: 10.1152/ajpgi.00326.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We reported previously that mechanical stretch in rat colonic obstruction induces cyclooxygenase (COX)-2 expression in smooth muscle cells. The aims of the present study were to investigate whether in vivo treatment with COX-2 inhibitor has prophylactic and therapeutic effects on motility dysfunction in colon obstruction, and if so what are the underlying mechanisms. Partial colon obstruction was induced with a silicon band in the distal colon of 6-8-wk-old Sprague-Dawley rats; obstruction was maintained for 3 days or 7 days. Daily administration of COX-2 inhibitor NS-398 (5 mg/kg) or vehicle was started before or after the induction of obstruction to study its prophylactic and therapeutic effects, respectively. The smooth muscle contractility was significantly suppressed, and colonic transit rate was slower in colonic obstruction. Prophylactic treatment with NS-398 significantly prevented the impairments of colonic transit and smooth muscle contractility and attenuated fecal collection in the occluded colons. When NS-398 was administered therapeutically 3 days after the initiation of obstruction, the muscle contractility and colonic transit still improved on day 7. Obstruction led to marked increase of COX-2 expression and prostaglandin E(2) (PGE(2)) synthesis. Exogenous PGE(2) decreased colonic smooth muscle contractility. All four PGE(2) E-prostanoid receptor types (EP1 to EP4) were detected in rat colonic muscularis externa. Treatments with EP1 and EP3 antagonists suppressed muscle contractility in control tissue but did not improve contractility in obstruction tissue. On the contrary, the EP2 and EP4 antagonists did not affect control tissue but significantly restored muscle contractility in obstruction. We concluded that our study shows that COX-2 inhibitor has prophylactic and therapeutic benefits for motility dysfunction in bowel obstruction. PGE(2) and its receptors EP2 and EP4 are involved in the motility dysfunction in obstruction, whereas EP1 and EP3 mediate PGE(2) regulation of colonic smooth muscle contractile function in normal state.
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Affiliation(s)
- You-Min Lin
- Division of Gastroenterology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas
| | - Sushil K. Sarna
- Division of Gastroenterology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas
| | - Xuan-Zheng Shi
- Division of Gastroenterology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas
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Hoffman JM, McKnight ND, Sharkey KA, Mawe GM. The relationship between inflammation-induced neuronal excitability and disrupted motor activity in the guinea pig distal colon. Neurogastroenterol Motil 2011; 23:673-e279. [PMID: 21426440 DOI: 10.1111/j.1365-2982.2011.01702.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Colitis is associated with increased excitability of afterhyperpolarization neurons (AH neurons) and facilitated synaptic transmission in the myenteric plexus. These changes are accompanied by disrupted propulsive motility, particularly in ulcerated regions. This study examined the relationship between myenteric AH neuronal hyperexcitability and disrupted propulsive motility. METHODS The voltage-activated Na(+) channel opener veratridine, the intermediate conductance Ca(2+) -activated K(+) channel inhibitor TRAM-34 and the 5-HT(4) receptor agonist tegaserod were used to evaluate the effects of neuronal hyperexcitability and synaptic facilitation on propulsive motility in normal guinea pig distal colon. Because trinitrobenzene sulfonic acid (TNBS)-colitis-induced hyperexcitability of myenteric afferent neurons involves increases in hyperpolarization-activated, cyclic nucleotide-gated (HCN) channel activity, the HCN channel inhibitors Cs(+) and ZD7288 were used to suppress AH neuronal activity in TNBS-colitis. KEY RESULTS In non-inflamed preparations, veratridine halted propulsive motility (P<0.001). The rate of propulsive motor activity was significantly reduced following addition of TRAM-34 and tegaserod (P<0.001). In TNBS-inflamed preparations, in which motility was temporarily halted or obstructed at sites of ulceration, both Cs(+) and ZD7288 normalized motility through the inflamed regions. Immunohistochemistry studies demonstrated that the proportion of AH neurons in the myenteric plexus was unchanged in ulcerated regions, but there was a 10% reduction in total number of neurons per ganglion. CONCLUSIONS AND INFERENCES These findings support the concept that inflammation-induced neuroplasticity in myenteric neurons, involving changes in ion channel activity that lead to enhanced AH neuronal excitability, can contribute to impaired propulsive colonic motility.
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Affiliation(s)
- J M Hoffman
- Department of Anatomy & Neurobiology, University of Vermont, Burlington, VT 05405, USA
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Shi XZ, Lin YM, Powell DW, Sarna SK. Pathophysiology of motility dysfunction in bowel obstruction: role of stretch-induced COX-2. Am J Physiol Gastrointest Liver Physiol 2011; 300:G99-G108. [PMID: 21051526 PMCID: PMC3025501 DOI: 10.1152/ajpgi.00379.2010] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In gastrointestinal conditions such as bowel obstruction, pseudo-obstruction, and idiopathic megacolon, the lumen of affected bowel segments is distended and its motility function impaired. Our hypothesis is that mechanical stretch of the distended segments alters gene expression of cyclooxygenase-2 (COX-2), which impairs motility function. Partial obstruction was induced with a silicon band in the distal colon of rats for up to 7 days, and wild-type and COX-2 gene-deficient mice for 4 days. Mechanical stretch was mimicked in vitro in colonic circular muscle strips and in primary culture of colonic circular smooth muscle cells (SMC) with a Flexercell system. The rat colonic circular muscle contractility was significantly decreased in the distended segment oral to obstruction, but not in the aboral segment. This change started as early as day 1 and persisted for at least 7 days after obstruction. The expression of COX-2 mRNA and protein increased dramatically also in the oral, but not aboral, segment. The upregulation of COX-2 expression started at 12 h and the effect persisted for 7 days. At 24 h after obstruction, the COX-2 mRNA level in the oral segment increased 26-fold compared with controls. This was not accompanied by any significant increase of myeloperoxidase or inflammatory cytokines. Immunohistochemical studies showed that COX-2 was selectively induced in the colonic SMC. In vitro stretch of colonic muscle strips or cultured SMC drastically induced COX-2 expression. Incubation of circular muscle strips from obstructed segment with COX-2 inhibitor NS-398 restored the contractility. The impairment of muscle contractility in obstructed colon was attenuated in the COX-2 gene-deficient mice. In conclusion, mechanical stretch in obstruction induces marked expression of COX-2 in the colonic SMC, and stretch-induced COX-2 plays a critical role in the suppression of smooth muscle contractility in bowel obstruction.
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Affiliation(s)
- Xuan-Zheng Shi
- Division of Gastroenterology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas 77555-0655, USA.
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31
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Abstract
The Gastrointestinal Motility Monitor (GIMM; Catamount Research and Development; St. Albans, VT) is an in vitro system that monitors propulsive motility in isolated segments of guinea pig distal colon. The complete system consists of a computer, video camera, illuminated organ bath, peristaltic and heated water bath circulating pumps, and custom GIMM software to record and analyze data. Compared with traditional methods of monitoring colonic peristalsis, the GIMM system allows for continuous, quantitative evaluation of motility. The guinea pig distal colon is bathed in warmed, oxygenated Krebs solution, and fecal pellets inserted in the oral end are propelled along the segment of colon at a rate of about 2 mm/sec. Movies of the fecal pellet proceeding along the segment are captured, and the GIMM software can be used track the progress of the fecal pellet. Rates of propulsive motility can be obtained for the entire segment or for any particular region of interest. In addition to analysis of bolus-induced motility patterns, spatiotemporal maps can be constructed from captured video segments to assess spontaneous motor activity patterns. Applications of this system include pharmacological evaluation of the effects of receptor agonists and antagonists on propulsive motility, as well as assessment of changes that result from pathophysiological conditions, such as inflammation or stress. The guinea pig distal colon propulsive motility assay, using the GIMM system, is straightforward and simple to learn, and it provides a reliable and reproducible method of assessing propulsive motility.
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Affiliation(s)
- Jill M Hoffman
- Department of Anatomy and Neurobiology, The University of Vermont, USA
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32
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Nurgali K, Qu Z, Hunne B, Thacker M, Pontell L, Furness JB. Morphological and functional changes in guinea-pig neurons projecting to the ileal mucosa at early stages after inflammatory damage. J Physiol 2010; 589:325-39. [PMID: 21098001 DOI: 10.1113/jphysiol.2010.197707] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In the present study the relationship between tissue damage and changed electro-physiological properties of Dogiel type II myenteric neurons within the first 24 hours after induction of inflammation with trinitrobenzene sulfonate (TNBS) in the guinea-pig ileum was investigated. Treatment with TNBS causes damage to the mucosa, inflammatory responses in the mucosa and enteric ganglia and changes in myenteric neuron properties. Thus we hypothesise that the physiological changes in the myenteric neurons could be due to damage to their mucosal processes or inflammation in the vicinity of cell bodies or the processes. We found an association between hyperexcitability of myenteric Dogiel type II neurons and damage to the mucosa and its innervation at 3 and 24 h, times when there was also an inflammatory reaction. The lack of hyperexcitability in neurons from control tissues in which axons projecting to the mucosa were severed suggests that inflammation may be an important contributing factor to the neuronal hyperexcitability at the acute stage of inflammation. Despite mucosal repair and re-innervation of the mucosa before 7 days after induction of inflammation, neuronal hyperexcitability persists. Although the mechanisms underlying neuronal hyperexcitability at the acute stage of inflammation might be different from those underlying long-term changes in the absence of active inflammation in the ganglia, the persistent changes in neuronal excitability may contribute to post-inflammatory gut dysfunctions.
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Affiliation(s)
- Kulmira Nurgali
- School of Biomedical and Health Sciences, Victoria University, Melbourne, Victoria, Australia.
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Lakhan SE, Kirchgessner A. Neuroinflammation in inflammatory bowel disease. J Neuroinflammation 2010; 7:37. [PMID: 20615234 PMCID: PMC2909178 DOI: 10.1186/1742-2094-7-37] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Accepted: 07/08/2010] [Indexed: 12/13/2022] Open
Abstract
Inflammatory bowel disease is a chronic intestinal inflammatory condition, the pathology of which is incompletely understood. Gut inflammation causes significant changes in neurally controlled gut functions including cramping, abdominal pain, fecal urgency, and explosive diarrhea. These symptoms are caused, at least in part, by prolonged hyperexcitability of enteric neurons that can occur following the resolution of colitis. Mast, enterochromaffin and other immune cells are increased in the colonic mucosa in inflammatory bowel disease and signal the presence of inflammation to the enteric nervous system. Inflammatory mediators include 5-hydroxytryptamine and cytokines, as well as reactive oxygen species and the production of oxidative stress. This review will discuss the effects of inflammation on enteric neural activity and potential therapeutic strategies that target neuroinflammation in the enteric nervous system.
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Affiliation(s)
- Shaheen E Lakhan
- Global Neuroscience Initiative Foundation, Los Angeles, CA, USA.
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Strong DS, Cornbrooks CF, Roberts JA, Hoffman JM, Sharkey KA, Mawe GM. Purinergic neuromuscular transmission is selectively attenuated in ulcerated regions of inflamed guinea pig distal colon. J Physiol 2010; 588:847-59. [PMID: 20064853 DOI: 10.1113/jphysiol.2009.185082] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
This study was undertaken to investigate neuromuscular transmission in regions of the inflamed colon in which motility is disrupted. Propulsive motility was evaluated in segments of control guinea pigs and those treated 6 days previously with trinitrobenzene sulfonic acid. Intracellular recordings were then obtained from circular muscle cells to examine excitatory and inhibitory junction potentials (EJPs and IJPs). In inflamed preparations, propulsion of fecal pellets was temporarily halted or obstructed at sites of mucosal damage, whereas the propulsive motility was linear in control colons. The amplitudes of evoked and spontaneous IJPs were significantly reduced in ulcerated regions of inflamed preparations, but EJPs were comparable to controls. Pharmacological dissection of the IJP revealed that the purinergic component was reduced, while the nitrergic IJP was slightly increased. Furthermore, the reduction in the purinergic IJP in inflamed preparations persisted in the presence of hexamethonium, suggesting that the deficit involved the inhibitory motor neuron and/or smooth muscle. Nerve fibre density was not altered in the circular muscle, and pre-contracted rings of inflamed colon relaxed normally to ATP, suggesting that the deficit involves altered ATP release and/or degradation. The P2Y(1) receptor antagonist MRS2179 slowed propulsive motility indicating that decreased purinergic neuromuscular transmission could contribute to the inflammation-induced motor deficit. We conclude that purinergic inhibitory neuronal input to the circular muscle is selectively reduced in regions of the colon in experimental colitis where the mucosa is damaged, and this is likely to contribute to altered motility in colitis by diminishing downstream relaxation during the peristaltic reflex.
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Affiliation(s)
- Derek S Strong
- D403A Given Building, Department of Anatomy and Neurobiology, University of Vermont, Burlington, VT 05405, USA
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35
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Fornai M, Antonioli L, Colucci R, Bernardini N, Ghisu N, Tuccori M, De Giorgio R, Del Tacca M, Blandizzi C. Emerging role of cyclooxygenase isoforms in the control of gastrointestinal neuromuscular functions. Pharmacol Ther 2010; 125:62-78. [DOI: 10.1016/j.pharmthera.2009.09.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Accepted: 09/16/2009] [Indexed: 02/06/2023]
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Kiank C, Taché Y, Larauche M. Stress-related modulation of inflammation in experimental models of bowel disease and post-infectious irritable bowel syndrome: role of corticotropin-releasing factor receptors. Brain Behav Immun 2010; 24:41-8. [PMID: 19698778 PMCID: PMC2962412 DOI: 10.1016/j.bbi.2009.08.006] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Revised: 08/07/2009] [Accepted: 08/14/2009] [Indexed: 12/14/2022] Open
Abstract
The interaction between gut inflammatory processes and stress is gaining increasing recognition. Corticotropin-releasing factor (CRF)-receptor activation in the brain is well established as a key signaling pathway initiating the various components of the stress response including in the viscera. In addition, a local CRF signaling system has been recently established in the gut. This review summarize the present knowledge on mechanisms through which both brain and gut CRF receptors modulate intestinal inflammatory processes and its relevance towards increased inflammatory bowel disease (IBD) activity and post-infectious irritable bowel syndrome (IBS) susceptibility induced by stress.
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Affiliation(s)
- Cornelia Kiank
- David Geffen School of Medicine at UCLA, CURE: Digestive Diseases Research Center-Animal Core, VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA.
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37
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Darmani NA, Ray AP. Evidence for a re-evaluation of the neurochemical and anatomical bases of chemotherapy-induced vomiting. Chem Rev 2009; 109:3158-99. [PMID: 19522506 DOI: 10.1021/cr900117p] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Nissar A Darmani
- Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, California 91766-1854, USA.
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38
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Mawe GM, Strong DS, Sharkey KA. Plasticity of enteric nerve functions in the inflamed and postinflamed gut. Neurogastroenterol Motil 2009; 21:481-91. [PMID: 19368664 PMCID: PMC2717558 DOI: 10.1111/j.1365-2982.2009.01291.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Inflammation of the gut alters the properties of the intrinsic and extrinsic neurons that innervate it. While the mechanisms of neuroplasticity differ amongst the inflammatory models that have been used, amongst various regions of the gut, and between intrinsic vs extrinsic neurons, a number of consistent features have been observed. For example, intrinsic and extrinsic primary afferent neurons become hyperexcitable in response to inflammation, and interneuronal synaptic transmission is facilitated in the enteric circuitry. These changes contribute to alterations in gut function and sensation in the inflamed bowel as well as functional disorders, and these changes persist for weeks beyond the point at which detectable inflammation has subsided. Thus, gaining a more thorough understanding of the mechanisms responsible for inflammation-induced neuroplasticity, and strategies to reverse these changes are clinically relevant goals. The purpose of this review is to summarize our current knowledge regarding neurophysiological changes that occur during and following intestinal inflammation, and to identify and address gaps in our knowledge regarding the role of enteric neuroplasticity in inflammatory and functional gastrointestinal disorders.
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Affiliation(s)
- Gary M. Mawe
- Department of Anatomy and Neurobiology, The University of Vermont College of Medicine, Burlington, VT, USA, Hotchkiss Brain Institute and Snyder Institute of Infection, Immunity and Inflammation, Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta, Canada
| | - Derek S. Strong
- Department of Anatomy and Neurobiology, The University of Vermont College of Medicine, Burlington, VT, USA
| | - Keith A. Sharkey
- Department of Anatomy and Neurobiology, The University of Vermont College of Medicine, Burlington, VT, USA, Hotchkiss Brain Institute and Snyder Institute of Infection, Immunity and Inflammation, Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta, Canada
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Hons IM, Burda JE, Grider JR, Mawe GM, Sharkey KA. Alterations to enteric neural signaling underlie secretory abnormalities of the ileum in experimental colitis in the guinea pig. Am J Physiol Gastrointest Liver Physiol 2009; 296:G717-26. [PMID: 19221017 PMCID: PMC2670664 DOI: 10.1152/ajpgi.90472.2008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Inflammatory bowel diseases (IBD) can involve widespread gastrointestinal dysfunction, even in cases in which inflammation is localized to a single site. The underlying pathophysiology of dysfunction in noninflamed regions is unclear. We examined whether colitis is associated with altered electrogenic ion transport in the ileal mucosa and/or changes in the properties of ileal submucosal neurons. Colitis was induced by administration of trinitrobenzene sulfonic acid (TNBS), and the uninflamed ileum from animals was examined 3, 7, and 28 days later. Electrogenic ion transport was assessed in Ussing chambers. Intracellular microelectrode recordings were used to examine the neurophysiology of the submucosal plexus of the ileum in animals with colitis. Noncholinergic secretion was reduced by 33% in the ileum from animals 7 days after the induction of colitis. The epithelial response to vasoactive intestinal peptide (VIP) was unaltered in animals with colitis, but the response to carbachol was enhanced. Slow excitatory synaptic transmission was dramatically reduced in VIP-expressing, noncholinergic secretomotor neurons. This change was detected as early as 3 days following TNBS treatment. No changes to fast synaptic transmission or the number of VIP neurons were observed. In addition, cholinergic secretomotor neurons fired more action potentials during a given stimulus, and intrinsic primary afferent neurons had broader action potentials in animals with colitis. These findings implicate changes to enteric neural circuits as contributing factors in inflammation-induced secretory dysfunction at sites proximal to a localized inflammatory insult.
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Affiliation(s)
- Ian M. Hons
- Snyder Institute of Infection, Immunity and Inflammation and Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Internal Medicine, Virginia Commonwealth University, Richmond, Virginia; and Department of Anatomy and Neurobiology, University of Vermont, Burlington, Vermont
| | - Joshua E. Burda
- Snyder Institute of Infection, Immunity and Inflammation and Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Internal Medicine, Virginia Commonwealth University, Richmond, Virginia; and Department of Anatomy and Neurobiology, University of Vermont, Burlington, Vermont
| | - John R. Grider
- Snyder Institute of Infection, Immunity and Inflammation and Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Internal Medicine, Virginia Commonwealth University, Richmond, Virginia; and Department of Anatomy and Neurobiology, University of Vermont, Burlington, Vermont
| | - Gary M. Mawe
- Snyder Institute of Infection, Immunity and Inflammation and Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Internal Medicine, Virginia Commonwealth University, Richmond, Virginia; and Department of Anatomy and Neurobiology, University of Vermont, Burlington, Vermont
| | - Keith A. Sharkey
- Snyder Institute of Infection, Immunity and Inflammation and Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Internal Medicine, Virginia Commonwealth University, Richmond, Virginia; and Department of Anatomy and Neurobiology, University of Vermont, Burlington, Vermont
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Inhibition of cyclooxygenase-2 and EP1 receptor antagonism reduces human colonic longitudinal muscle contractility in vitro. Prostaglandins Other Lipid Mediat 2008; 88:117-21. [PMID: 19126433 DOI: 10.1016/j.prostaglandins.2008.12.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 12/03/2008] [Accepted: 12/06/2008] [Indexed: 11/24/2022]
Abstract
We investigated the contribution of cyclo-oxygenase enzyme inhibition and prostamide agonism on human colonic contractility in vitro. The effects of the non-specific COX inhibitor diclofenac were compared against selective COX-2 inhibition via nimesulide, the prostanoid EP(1) receptor antagonist SC19220 or the prostaglandin prodrug/prostamide receptor agonist bimatoprost, on potency of contraction to acetylcholine in human colonic circular and longitudinal muscle strips. Pre-treatment with either nimesulide (10(-5)M) or diclofenac (10(-6)M) caused a significant decrease in the potency of acetylcholine-evoked longitudinal muscle contraction, but did not inhibit acetylcholine-evoked circular muscle contraction. Pre-treatment with the EP(1) receptor antagonist SC19220 (10(-5)M) similarly decreased cholinergic potency in longitudinal muscle, without influence on circular muscle contraction. The prostamide agonist bimatoprost (10(-6)M) increased basal circular and longitudinal muscle tone, but did not alter cholinergic potency in either muscle layer. In conclusion, colonic longitudinal muscle contraction is augmented by COX-2 activity, most likely via PGE(2) acting at EP(1) receptors. While colonic contraction is tonically modulated by bimatoprost, it does not share the same functional properties attributed to other endogenous COX-2 metabolites on colonic contractile function.
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Barbara G, Stanghellini V, Cremon C, De Giorgio R, Corinaldesi R. What is the effect of inflammation on intestinal function? Inflamm Bowel Dis 2008; 14 Suppl 2:S140-4. [PMID: 18816685 DOI: 10.1002/ibd.20701] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Giovanni Barbara
- Department of Internal Medicine and Gastroenterology, University of Italy, Bologna, Italy
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Gomez-Pinilla PJ, Camello PJ, Pozo MJ. Protective effect of melatonin on Ca2+ homeostasis and contractility in acute cholecystitis. J Pineal Res 2008; 44:250-60. [PMID: 18339120 DOI: 10.1111/j.1600-079x.2007.00520.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Impaired Ca2+ homeostasis and smooth muscle contractility co-exist in acute cholecystitis (AC) leading to gallbladder dysfunction. There is no pharmacological treatment for this pathological condition. Our aim was to evaluate the effects of melatonin treatment on Ca2+ signaling pathways and contractility altered by cholecystitis. [Ca2+]i was determined by epifluorescence microscopy in fura-2 loaded isolated gallbladder smooth muscle cells, and isometric tension was recorded from gallbladder muscle strips. Malondialdehyde (MDA) and reduced glutathione (GSH) contents were determined by spectrophotometry and cycloxygenase-2 (COX-2) expression was quantified by western blot. Melatonin was tested in two experimental groups, one of which underwent common bile duct ligation for 2 days and another that was later de-ligated for 2 days. Inflammation-induced impairment of Ca2+ responses to cholecystokinin and caffeine were recovered by melatonin treatment (30 mg/kg). This treatment also ameliorated the detrimental effects of AC on Ca2+ influx through both L-type and capacitative Ca2+ channels, and it was effective in preserving the pharmacological phenotype of these channels. Despite its effects on Ca2+ homeostasis, melatonin did not improve contractility. After de-ligation, Ca2+ influx and contractility were still impaired, but both were recovered by melatonin. These effects of melatonin were associated to a reduction of MDA levels, an increase in GSH content and a decrease in COX-2 expression. These findings indicate that melatonin restores Ca2+ homeostasis during AC and resolves inflammation. In addition, this indoleamine helps in the subsequent recovery of functionality.
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De Schepper HU, De Man JG, Moreels TG, Pelckmans PA, De Winter BY. Review article: gastrointestinal sensory and motor disturbances in inflammatory bowel disease - clinical relevance and pathophysiological mechanisms. Aliment Pharmacol Ther 2008; 27:621-37. [PMID: 18221407 DOI: 10.1111/j.1365-2036.2008.03624.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND It is well known that inflammation has a profound impact on the neuromuscular apparatus of the gastrointestinal tract during the inflammatory insult and in periods of remission, at the site of inflammation and at distance from this site. The importance of this interaction is illustrated by the higher prevalence of functional gut disorders in patients with inflammatory bowel disease. AIMS To document the epidemiological and clinical significance of functional alterations of gut motility and sensitivity in patients with inflammatory bowel disease and to formulate potential pathophysiological mechanisms. RESULTS AND CONCLUSIONS Functional gut disorders occur frequently in patients with inflammatory bowel disease, both during inflammatory episodes and in periods of remission, and have a major impact on their quality of life. The clinical manifestations of these motility and sensitivity disorders vary and are often difficult to treat, mainly because therapeutic guidelines and specific diagnostic tests to distinguish inflammatory bowel disease from functional gut disorders are lacking. Chronic bowel inflammation results in a complicated interaction between neuroendocrine serotonin-predominant cells of the mucosa, inflammatory cells (particularly mast cells) in the submucosa, the intrinsic and extrinsic innervation and the muscular apparatus including the interstitial cells of Cajal. The outcome of this interaction is a perturbation of gastrointestinal motor function, both locally and at distance from the site of inflammation and during both acute inflammation and remission.
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Affiliation(s)
- H U De Schepper
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium
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45
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Krauter EM, Strong DS, Brooks EM, Linden DR, Sharkey KA, Mawe GM. Changes in colonic motility and the electrophysiological properties of myenteric neurons persist following recovery from trinitrobenzene sulfonic acid colitis in the guinea pig. Neurogastroenterol Motil 2007; 19:990-1000. [PMID: 17973636 DOI: 10.1111/j.1365-2982.2007.00986.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Persistent changes in gastrointestinal motility frequently accompany the resolution of colitis, through mechanisms that remain to be determined. Trinitrobenzene sulfonic acid (TNBS) colitis in the guinea pig decreases the rate of propulsive motility, causes hyperexcitability of AH neurons, and induces synaptic facilitation. The changes in motility and AH neurons are sensitive to cyclooxygenase-2 (COX-2) inhibition. The aim of this investigation was to determine if the motility and neurophysiological changes persist following recovery from colitis. Evaluations of inflammation, colonic motility and intracellular electrophysiology of myenteric neurons 8 weeks after TNBS administration were performed and compared to matched control conditions. Myeloperoxidase levels in the colons were comparable to control levels 56 days after TNBS treatment. At this time point, the rate of colonic motility was decreased relative to controls following treatment with TNBS alone or TNBS plus a COX-2 inhibitor. Furthermore, the electrical properties of AH neurons and fast synaptic potentials in S neurons were significantly different from controls and comparable to those detected during active inflammation. Collectively, these data suggest that altered myenteric neurophysiology initiated during active colitis persists long term, and provide a potential mechanism underlying altered gut function in individuals during remission from inflammatory bowel disease.
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Affiliation(s)
- E M Krauter
- Department of Anatomy and Neurobiology, The University of Vermont College of Medicine, Burlington, VT 05405, USA
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Alterations in spontaneous contractions of rat ileum and jejunum after peritonitis. Eur J Pharmacol 2007; 580:250-5. [PMID: 18029280 DOI: 10.1016/j.ejphar.2007.10.064] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Revised: 10/17/2007] [Accepted: 10/22/2007] [Indexed: 11/23/2022]
Abstract
The aim of this study was to investigate the effects of peritonitis on spontaneous contractions of ileum and jejunum smooth muscles isolated from rats. Peritonitis was induced by cecal ligation and puncture in 8 rats. Another group of 8 rats underwent a sham operation and acted as controls. Twenty-four hours after the operation, the rats were killed, and their ileum and jejunum smooth muscles were excised and placed in circular muscle direction in a 10 ml organ bath. Changes in the amplitude and frequency of spontaneous contractions were analyzed before and after the addition of different antagonists. Peritonitis induced the decrease in the amplitude and frequency of spontaneous contractions in ileum and jejunum smooth muscles. In control groups, both ileum and jejunum, the amplitude and frequency of spontaneous contractions were significantly elevated in the presence of N(G)-nitro-L-arginine (L-NNA) and indomethacin. In peritonitis groups, both ileum and jejunum, the amplitude and frequency of spontaneous contractions were significantly enhanced in the presence of L-NNA, aminoguanidine, indomethacin and celecoxib compared to control values. In conclusion, peritonitis induces the decrease in the amplitude and frequency of spontaneous contractions of ileum and jejunum that can be attributed to the rise of nitric oxide synthase and cyclooxygenase isoforms levels.
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Klinger MB, Dattilio A, Vizzard MA. Expression of cyclooxygenase-2 in urinary bladder in rats with cyclophosphamide-induced cystitis. Am J Physiol Regul Integr Comp Physiol 2007; 293:R677-85. [PMID: 17537839 DOI: 10.1152/ajpregu.00305.2007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
These studies examined the expression of cyclooxygenase-2 (COX-2) expression in the urothelium and suburothelial space and detrusor from rats treated with cyclophosphamide (CYP) to induce acute (4 h), intermediate (48 h), or chronic (10-day) cystitis. Western blot analysis and immunohistochemistry were used to demonstrate COX-2 expression. In whole mount preparations of urinary bladder, nerve fibers in the suburothelial plexus, and inflammatory cell infiltrates were characterized for COX-2 expression after CYP-induced cystitis. COX-2 expression significantly (P <or= 0.01) increased in the urothelium + suburothelium and detrusor smooth muscle with acute, intermediate, and chronic (10-day) CYP-induced cystitis, but expression in urothelium + suburothelium was significantly greater. CYP-induced upregulation of COX-2 showed by immunostaining in the urothelium + suburothelium was similar to that observed with Western blot analysis and also demonstrated COX-2 inflammatory cell infiltrates (CD86+) and nerve fibers (PGP+) in the suburothelial plexus. Although COX-2 expression was significantly (P <or= 0.01) increased in detrusor smooth muscle, immunohistochemistry failed to demonstrate an obvious change in COX-2-immunoreactivity (IR) in detrusor muscle, but COX-2 inflammatory infiltrates were present throughout the detrusor. COX-2-IR nerve fibers exhibited increased density in the suburothelial plexus with acute or chronic CYP-induced cystitis. COX-2-IR macrophages (CD86+) were present throughout the urinary bladder with acute and chronic CYP-induced cystitis. These studies demonstrate cellular targets in the urinary bladder where COX-2 inhibitors may act.
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Affiliation(s)
- Mary Beth Klinger
- Univ. of Vermont College of Medicine, Dept. of Neurology, D415A Given Research Bldg., Burlington, VT 05405. )
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Ferens D, Baell J, Lessene G, Smith JE, Furness JB. Effects of modulators of Ca(2+)-activated, intermediate-conductance potassium channels on motility of the rat small intestine, in vivo. Neurogastroenterol Motil 2007; 19:383-9. [PMID: 17509020 DOI: 10.1111/j.1365-2982.2007.00898.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The movements of the intestine shift between different motor patterns, including between propulsion and mixing, but there is little information concerning mechanisms that may lead to changes in the patterns of motility. We have investigated the influence on intestinal motility of drugs that affect the after-hyperpolarization potential (AHP) of intrinsic primary afferent neurons (IPANs). The current of the AHP is carried by the intermediate conductance, calcium-activated, potassium (IK) channel. In anaesthetized rats, the IK channel blocker, 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (0.05-1 mg kg(-1), i.v.) disrupted the regular propulsive pressure waves that occur in the small intestine and reduced propulsion of the contents (after 1 mg kg(-1), the fluid propelled was <25% of control). If the propulsion in the intestine was regular, the IK channel opener, 5,6-dichloro-1-ethyl-2-benzimidazolinone (DC-EBIO, 0.1 mg kg(-1) h(-1)) had no effect. DC-EBIO (0.1 mg kg(-1) h(-1)) restored propulsive activity after the nitric oxide synthase inhibitor, Nomega-nitro-l-arginine had changed motility to a mixing pattern. We suggest that the AHP determines the synchrony of action potential firing in synaptically coupled IPANs, and that this synchrony influences the patterns of firing of muscle motor neurons, and hence the pattern of contraction of the muscle and whether the pattern is predominantly propulsive or predominantly mixing.
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Affiliation(s)
- D Ferens
- Department of Anatomy and Cell Biology and Centre for Neuroscience, University of Melbourne, Parkville, Victoria, Australia
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Krauter EM, Linden DR, Sharkey KA, Mawe GM. Synaptic plasticity in myenteric neurons of the guinea-pig distal colon: presynaptic mechanisms of inflammation-induced synaptic facilitation. J Physiol 2007; 581:787-800. [PMID: 17363386 PMCID: PMC2075198 DOI: 10.1113/jphysiol.2007.128082] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The purpose of this study was to investigate the pre- and postsynaptic mechanisms that contribute to synaptic facilitation in the myenteric plexus of the trinitrobenzene sulphonic acid-inflamed guinea-pig distal colon. Intracellular recordings of evoked fast excitatory postsynaptic potentials (fEPSPs) in myenteric S neurons were evaluated, and the density of synaptic terminals was morphometrically analysed by transmission electron microscopy. In inflamed tissue, fEPSPs were reduced to control levels by the protein kinase A (PKA) inhibitor, H89, but H89 did not affect the fEPSPs in control tissue. This PKA activation in inflamed tissue did not appear to involve 5-HT(4) receptors because the antagonist/inverse agonist, GR 125487, caused comparable decreases of fEPSPs in both tissues. Inhibition of BK channels with iberiotoxin did not alter the fEPSPs in inflamed tissue, but increased the fEPSPs in control tissue to the amplitude detected in inflamed tissue. During trains of stimuli, run-down of EPSPs was less extensive in inflamed tissue and there was a significant increase in the paired pulse ratio. Depolarizations in response to exogenous neurotransmitters were not altered in inflamed tissue. These inflammation-induced changes were not accompanied by alterations in the pharmacological profile of EPSPs, and no changes in synaptic density were detected by electron microscopy. Collectively, these data indicate that synaptic facilitation in the inflamed myenteric plexus involves a presynaptic increase in PKA activity, possibly involving an inhibition of BK channels, and an increase in the readily releasable pool of synaptic vesicles.
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Affiliation(s)
- Eric M Krauter
- Department of Anatomy and Neurobiology, University of Vermont College of Medicine, Burlington, VT 05405, USA
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Lomax AE, O'Hara JR, Hyland NP, Mawe GM, Sharkey KA. Persistent alterations to enteric neural signaling in the guinea pig colon following the resolution of colitis. Am J Physiol Gastrointest Liver Physiol 2007; 292:G482-91. [PMID: 17008554 DOI: 10.1152/ajpgi.00355.2006] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Functional changes induced by inflammation persist following recovery from the inflammatory response, but the mechanisms underlying these changes are not well understood. Our aim was to investigate whether the excitability and synaptic properties of submucosal neurons remained altered 8 wk post-trinitrobenzene sulfonic acid (TNBS) treatment and to determine whether these changes were accompanied by alterations in secretory function in submucosal preparations voltage clamped in Ussing chambers. Mucosal serotonin (5-HT) release measurements and 5-HT reuptake transporter (SERT) immunohistochemistry were also performed. Eight weeks after TNBS treatment, colonic inflammation resolved, as assessed macroscopically and by myeloperoxidase assay. However, fast excitatory postsynaptic potential (fEPSP) amplitude was significantly increased in submucosal S neurons from previously inflamed colons relative to those in control tissue. In addition, fEPSPs from previously inflamed colons had a hexamethonium-insensitive component that was not evident in age-matched controls. AH neurons were hyperexcitable, had shorter action potential durations, and decreased afterhyperpolarization 8 wk following TNBS adminstration. Neuronally mediated colonic secretory function was significantly reduced after TNBS treatment, although epithelial cell signaling, as measured by responsiveness to both forskolin and bethanecol in the presence of tetrodotoxin, was comparable with control tissue. 5-HT levels and SERT immunoreactivity were comparable to controls 8 wk after the induction of inflammation, but there was an increase in glucagon-like peptide 2-immunoreactive L cells. In conclusion, sustained alterations in enteric neural signaling occur following the resolution of colitis, which are accompanied by functional changes in the absence of active inflammation.
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Affiliation(s)
- Alan E Lomax
- Gastrointestinal Diseases Research Unit, Department of Medicine, Queen's University, Kingston, Ontario, Canada
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