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Wang D, Wang W, Wang P, Wang C, Niu J, Liu Y, Chen Y. Research progress of colon-targeted oral hydrogel system based on natural polysaccharides. Int J Pharm 2023; 643:123222. [PMID: 37454829 DOI: 10.1016/j.ijpharm.2023.123222] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 06/20/2023] [Accepted: 07/08/2023] [Indexed: 07/18/2023]
Abstract
The quality of life is significantly impacted by colon-related diseases. There have been a lot of interest in the oral colon-specific drug delivery system (OCDDS) as a potential carrier to decrease systemic side effects and protect drugs from degradation in the upper gastrointestinal tract (GIT). Hydrogels are effective oral colon-targeted drug delivery carriers due to their high biodegradability, substantial drug loading, and great biocompatibility. Natural polysaccharides give the hydrogel system unique structure and function to effectively respond to the complex environment of the GIT and deliver drugs to the colon. In this paper, the physiological factors of colonic drug delivery and the pathological characteristics of common colonic diseases are summarized, and the latest advances in the design, preparation and characterization of natural polysaccharide hydrogels are reviewed, which are expected to provide new references for colon-targeted oral hydrogel systems using natural polysaccharides as raw materials.
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Affiliation(s)
- Dingding Wang
- Key Laboratory of Therapeutic Substance of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Weibo Wang
- Key Laboratory of Therapeutic Substance of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Ping Wang
- Key Laboratory of Therapeutic Substance of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Chuang Wang
- Shenyang Pharmaceutical University, Shenyang, China
| | - Juntao Niu
- Department of Otorhinolaryngology, Head and Neck Surgery, the Second Hospital, Tianjin Medical University, Tianjin, China
| | - Yang Liu
- Key Laboratory of Therapeutic Substance of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China.
| | - Yuzhou Chen
- Key Laboratory of Therapeutic Substance of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China.
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2
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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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3
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Bayrer JR, Castro J, Venkataraman A, Touhara KK, Rossen ND, Morrie RD, Maddern J, Hendry A, Braverman KN, Garcia-Caraballo S, Schober G, Brizuela M, Castro Navarro FM, Bueno-Silva C, Ingraham HA, Brierley SM, Julius D. Gut enterochromaffin cells drive visceral pain and anxiety. Nature 2023; 616:137-142. [PMID: 36949192 PMCID: PMC10827380 DOI: 10.1038/s41586-023-05829-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 02/10/2023] [Indexed: 03/24/2023]
Abstract
Gastrointestinal (GI) discomfort is a hallmark of most gut disorders and represents an important component of chronic visceral pain1. For the growing population afflicted by irritable bowel syndrome, GI hypersensitivity and pain persist long after tissue injury has resolved2. Irritable bowel syndrome also exhibits a strong sex bias, afflicting women three times more than men1. Here, we focus on enterochromaffin (EC) cells, which are rare excitable, serotonergic neuroendocrine cells in the gut epithelium3-5. EC cells detect and transduce noxious stimuli to nearby mucosal nerve endings3,6 but involvement of this signalling pathway in visceral pain and attendant sex differences has not been assessed. By enhancing or suppressing EC cell function in vivo, we show that these cells are sufficient to elicit hypersensitivity to gut distension and necessary for the sensitizing actions of isovalerate, a bacterial short-chain fatty acid associated with GI inflammation7,8. Remarkably, prolonged EC cell activation produced persistent visceral hypersensitivity, even in the absence of an instigating inflammatory episode. Furthermore, perturbing EC cell activity promoted anxiety-like behaviours which normalized after blockade of serotonergic signalling. Sex differences were noted across a range of paradigms, indicating that the EC cell-mucosal afferent circuit is tonically engaged in females. Our findings validate a critical role for EC cell-mucosal afferent signalling in acute and persistent GI pain, in addition to highlighting genetic models for studying visceral hypersensitivity and the sex bias of gut pain.
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Affiliation(s)
- James R Bayrer
- Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA.
| | - Joel Castro
- College of Medicine and Public Health, Flinders Health and Medical Research Institute, Adelaide, South Australia, Australia
- Hopwood Centre for Neurobiology, Lifelong Health, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, South Australia, Australia
| | - Archana Venkataraman
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, USA
| | - Kouki K Touhara
- Department of Physiology, University of California, San Francisco, CA, USA
| | - Nathan D Rossen
- Department of Physiology, University of California, San Francisco, CA, USA
- Tetrad Graduate Program, University of California, San Francisco, CA, USA
| | - Ryan D Morrie
- Department of Physiology, University of California, San Francisco, CA, USA
- Maze Therapeutics, San Francisco, CA, USA
| | - Jessica Maddern
- College of Medicine and Public Health, Flinders Health and Medical Research Institute, Adelaide, South Australia, Australia
- Hopwood Centre for Neurobiology, Lifelong Health, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, South Australia, Australia
| | - Aenea Hendry
- College of Medicine and Public Health, Flinders Health and Medical Research Institute, Adelaide, South Australia, Australia
- Hopwood Centre for Neurobiology, Lifelong Health, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, South Australia, Australia
| | - Kristina N Braverman
- Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
- Jansen, Johnson & Johnson, San Diego, CA, USA
| | - Sonia Garcia-Caraballo
- College of Medicine and Public Health, Flinders Health and Medical Research Institute, Adelaide, South Australia, Australia
- Hopwood Centre for Neurobiology, Lifelong Health, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, South Australia, Australia
| | - Gudrun Schober
- College of Medicine and Public Health, Flinders Health and Medical Research Institute, Adelaide, South Australia, Australia
- Hopwood Centre for Neurobiology, Lifelong Health, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, South Australia, Australia
| | - Mariana Brizuela
- College of Medicine and Public Health, Flinders Health and Medical Research Institute, Adelaide, South Australia, Australia
- Hopwood Centre for Neurobiology, Lifelong Health, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, South Australia, Australia
| | | | - Carla Bueno-Silva
- Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
| | - Holly A Ingraham
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, USA.
| | - Stuart M Brierley
- College of Medicine and Public Health, Flinders Health and Medical Research Institute, Adelaide, South Australia, Australia.
- Hopwood Centre for Neurobiology, Lifelong Health, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, South Australia, Australia.
| | - David Julius
- Department of Physiology, University of California, San Francisco, CA, USA.
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4
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Martinello K, Sucapane A, Fucile S. 5-HT3 Receptors in Rat Dorsal Root Ganglion Neurons: Ca 2+ Entry and Modulation of Neurotransmitter Release. LIFE (BASEL, SWITZERLAND) 2022; 12:life12081178. [PMID: 36013357 PMCID: PMC9409985 DOI: 10.3390/life12081178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 07/29/2022] [Accepted: 07/31/2022] [Indexed: 11/16/2022]
Abstract
Rat dorsal root ganglion (DRG) neurons express 5-hydroxytryptamine receptors (5-HT3Rs). To elucidate their physiological role in the modulation of sensory signaling, we aimed to quantify their functional expression in newborn and adult rat DRG neurons, as well as their ability to modulate the Ca2+-dependent neurotransmitter release, by means of electrophysiological techniques combined with fluorescence-based Ca2+ imaging. The selective 5-HT3R agonist mCPBG (10 μM) elicited whole-cell currents in 92.5% of adult DRG neurons with a significantly higher density current than in responding newborn cells (52.2%), suggesting an increasing serotoninergic modulation on primary afferent cells during development. Briefly, 5-HT3Rs expressed by adult DRG neurons are permeable to Ca2+ ions, with a measured fractional Ca2+ current (i.e., the percentage of total current carried by Ca2+ ions, Pf) of 1.0%, similar to the value measured for the human heteromeric 5-HT3A/B receptor (Pf = 1.1%), but lower than that of the human homomeric 5-HT3A receptor (Pf = 3.5%). mCPBG applied to co-cultures of newborn DRG and spinal neurons significantly increased the miniature excitatory postsynaptic currents (mEPSCs) frequency in a subset of recorded spinal neurons, even in the presence of Cd2+, a voltage-activated Ca2+ channel blocker. Considered together, our findings indicate that the Ca2+ influx through heteromeric 5-HT3Rs is sufficient to increase the spontaneous neurotransmitter release from DRG to spinal neurons.
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Affiliation(s)
| | - Antonietta Sucapane
- Department of Physiology and Pharmacology, Sapienza University of Rome, P.le Aldo Moro, 5, 00185 Rome, Italy;
| | - Sergio Fucile
- IRCCS Neuromed, Via Atinense, 86077 Pozzilli, Italy;
- Department of Physiology and Pharmacology, Sapienza University of Rome, P.le Aldo Moro, 5, 00185 Rome, Italy;
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5
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Giniatullin R. 5-hydroxytryptamine in migraine: The puzzling role of ionotropic 5-HT 3 receptor in the context of established therapeutic effect of metabotropic 5-HT 1 subtypes. Br J Pharmacol 2021; 179:400-415. [PMID: 34643938 DOI: 10.1111/bph.15710] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 09/27/2021] [Accepted: 09/28/2021] [Indexed: 12/16/2022] Open
Abstract
5-hydroxytryptamine (5-HT; serotonin) is traditionally considered as a key mediator implicated in migraine. Multiple 5-HT receptor subtypes contribute to a variety of region-specific functional effects. The raphé nuclei control nociceptive inputs by releasing 5-HT in the brainstem, whereas dural mast cells provide the humoral source of 5-HT in the meninges. Triptans (5-HT1B/D agonists) and ditans (5-HT1F agonists) are the best established 5-HT anti-migraine agents. However, activation of meningeal afferents via ionotropic 5-HT3 receptors results in long-lasting excitatory drive suggesting a pro-nociceptive role for these receptors in migraine. Nevertheless, clinical data do not clearly support the applicability of currently available 5-HT3 antagonists to migraine treatment. The reasons for this might be the presence of 5-HT3 receptors on inhibitory interneurons dampening the excitatory drive, a lack of 5-HT3 A-E subunit-selective antagonists and gender/age-dependent effects. This review is focusing on the controversial role of 5-HT3 receptors in migraine pathology and related pharmacological perspectives of 5-HT ligands.
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Affiliation(s)
- Rashid Giniatullin
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.,Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
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6
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Yu Y, Villalobos-Hernandez EC, Pradhananga S, Baker CC, Keating C, Grundy D, Lomax AE, Reed DE. Deoxycholic acid activates colonic afferent nerves via 5-HT 3 receptor-dependent and -independent mechanisms. Am J Physiol Gastrointest Liver Physiol 2019; 317:G275-G284. [PMID: 31216174 DOI: 10.1152/ajpgi.00016.2019] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Increased bile acids in the colon can evoke increased epithelial secretion resulting in diarrhea, but little is known about whether colonic bile acids contribute to abdominal pain. This study aimed to investigate the mechanisms underlying activation of colonic extrinsic afferent nerves and their neuronal cell bodies by a major secondary bile acid, deoxycholic acid (DCA). All experiments were performed on male C57BL/6 mice. Afferent sensitivity was evaluated using in vitro extracellular recordings from mesenteric nerves in the proximal colon (innervated by vagal and spinal afferents) and distal colon (spinal afferents only). Neuronal excitability of cultured dorsal root ganglion (DRG) and nodose ganglion (NG) neurons was examined with perforated patch clamp. Colonic 5-HT release was assessed using ELISA, and 5-HT immunoreactive enterochromaffin (EC) cells were quantified. Intraluminal DCA increased afferent nerve firing rate concentration dependently in both proximal and distal colon. This DCA-elicited increase was significantly inhibited by a 5-HT3 antagonist in the proximal colon but not in the distal colon, which may be in part due to lower 5-HT immunoreactive EC cell density and lower 5-HT levels in the distal colon following DCA stimulation. DCA increased the excitability of DRG neurons, whereas it decreased the excitability of NG neurons. DCA potentiated mechanosensitivity of high-threshold spinal afferents independent of 5-HT release. Together, this study suggests that DCA can excite colonic afferents via direct and indirect mechanisms but the predominant mechanism may differ between vagal and spinal afferents. Furthermore, DCA increased mechanosensitivity of high-threshold spinal afferents and may be a mechanism of visceral hypersensitivity.NEW & NOTEWORTHY Deoxycholic acid (DCA) directly excites spinal afferents and, to a lesser extent, indirectly via mucosal 5-HT release. DCA potentiates mechanosensitivity of high-threshold spinal afferents independent of 5-HT release. DCA increases vagal afferent firing in proximal colon via 5-HT release but directly inhibits the excitability of their cell bodies.
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Affiliation(s)
- Yang Yu
- Gastrointestinal Diseases Research Unit, Queen's University, Kingston, Ontario, Canada
| | | | - Sabindra Pradhananga
- Gastrointestinal Diseases Research Unit, Queen's University, Kingston, Ontario, Canada
| | - Corey C Baker
- Gastrointestinal Diseases Research Unit, Queen's University, Kingston, Ontario, Canada
| | - Christopher Keating
- Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom
| | - David Grundy
- Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom
| | - Alan E Lomax
- Gastrointestinal Diseases Research Unit, Queen's University, Kingston, Ontario, Canada
| | - David E Reed
- Gastrointestinal Diseases Research Unit, Queen's University, Kingston, Ontario, Canada
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7
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Gong S, Yan Z, Liu Z, Niu M, Fang H, Li N, Huang C, Li L, Chen G, Luo H, Chen X, Zhou H, Hu J, Yang W, Huang Q, Schnabl B, Chang P, Billiar TR, Jiang Y, Chen P. Intestinal Microbiota Mediates the Susceptibility to Polymicrobial Sepsis-Induced Liver Injury by Granisetron Generation in Mice. Hepatology 2019; 69:1751-1767. [PMID: 30506577 DOI: 10.1002/hep.30361] [Citation(s) in RCA: 96] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 11/13/2018] [Indexed: 12/25/2022]
Abstract
Sepsis-induced liver injury is recognized as a key problem in intensive care units. The gut microbiota has been touted as an important mediator of liver disease development; however, the precise roles of gut microbiota in regulating sepsis-induced liver injury are unknown. Here, we aimed to investigate the role of the gut microbiota in sepsis-induced liver injury and the underlying mechanism. Cecal ligation and puncture (CLP) was used to induce polymicrobial sepsis and related liver injury. Fecal microbiota transplantation (FMT) was used to validate the roles of gut microbiota in these pathologies. Metabolomics analysis was performed to characterize the metabolic profile differences between sepsis-resistant (Res; survived to 7 days after CLP) and sepsis-sensitive (Sen; moribund before or approximately 24 hours after CLP) mice. Mice gavaged with feces from Sen mice displayed more-severe liver damage than did mice gavaged with feces from Res mice. The gut microbial metabolic profile between Sen and Res mice was different. In particular, the microbiota from Res mice generated more granisetron, a 5-hydroxytryptamine 3 (5-HT3 ) receptor antagonist, than the microbiota from Sen mice. Granisetron protected mice against CLP-induced death and liver injury. Moreover, proinflammatory cytokine expression by macrophages after lipopolysaccharide (LPS) challenge was markedly reduced in the presence of granisetron. Both treatment with granisetron and genetic knockdown of the 5-HT3A receptor in cells suppressed nuclear factor kappa B (NF-кB) transactivation and phosphorylated p38 (p-p38) accumulation in macrophages. Gut microbial granisetron levels showed a significantly negative correlation with plasma alanine aminotransferase (ALT)/aspartate aminotransferase (AST) levels in septic patients. Conclusion: Our study indicated that gut microbiota plays a key role in the sensitization of sepsis-induced liver injury and associates granisetron as a hepatoprotective compound during sepsis development.
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Affiliation(s)
- Shenhai Gong
- Department of Intensive Care Unit, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Department of Pathophysiology, Guangdong Provincial Key Laboratory of Proteomics, Southern Medical University, Guangzhou, China.,State Key Laboratory of Organ Failure Research, Southern Medical University, Guangzhou, China
| | - Zhengzheng Yan
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Proteomics, Southern Medical University, Guangzhou, China.,State Key Laboratory of Organ Failure Research, Southern Medical University, Guangzhou, China
| | - Zhanguo Liu
- Department of Intensive Care Unit, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Mengwei Niu
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Proteomics, Southern Medical University, Guangzhou, China.,State Key Laboratory of Organ Failure Research, Southern Medical University, Guangzhou, China
| | - Heng Fang
- Department of Intensive Care Unit, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Na Li
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Proteomics, Southern Medical University, Guangzhou, China.,State Key Laboratory of Organ Failure Research, Southern Medical University, Guangzhou, China
| | - Chenyang Huang
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Proteomics, Southern Medical University, Guangzhou, China
| | - Lei Li
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Proteomics, Southern Medical University, Guangzhou, China
| | - Guiming Chen
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Proteomics, Southern Medical University, Guangzhou, China
| | - Haihua Luo
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Proteomics, Southern Medical University, Guangzhou, China
| | - Xiaojiao Chen
- Division of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Microbiome Medicine Center, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Hongwei Zhou
- State Key Laboratory of Organ Failure Research, Southern Medical University, Guangzhou, China.,Division of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Microbiome Medicine Center, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Jingjuan Hu
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Proteomics, Southern Medical University, Guangzhou, China.,State Key Laboratory of Organ Failure Research, Southern Medical University, Guangzhou, China
| | - Wei Yang
- Microbiome Medicine Center, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Department of Pathology, Southern Medical University, Guangzhou, China
| | - Qiaobing Huang
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Proteomics, Southern Medical University, Guangzhou, China
| | - Bernd Schnabl
- Department of Medicine, University of California San Diego, La Jolla, CA
| | - Ping Chang
- Department of Intensive Care Unit, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | | | - Yong Jiang
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Proteomics, Southern Medical University, Guangzhou, China.,State Key Laboratory of Organ Failure Research, Southern Medical University, Guangzhou, China
| | - Peng Chen
- Department of Intensive Care Unit, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Department of Pathophysiology, Guangdong Provincial Key Laboratory of Proteomics, Southern Medical University, Guangzhou, China.,State Key Laboratory of Organ Failure Research, Southern Medical University, Guangzhou, China.,Microbiome Medicine Center, Zhujiang Hospital, Southern Medical University, Guangzhou, China
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8
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Camilleri M. Management Options for Irritable Bowel Syndrome. Mayo Clin Proc 2018; 93:1858-1872. [PMID: 30522596 PMCID: PMC6314474 DOI: 10.1016/j.mayocp.2018.04.032] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 04/23/2018] [Accepted: 04/27/2018] [Indexed: 02/07/2023]
Abstract
Irritable bowel syndrome (IBS) is associated with diverse pathophysiologic mechanisms. These mechanisms include increased abnormal colonic motility or transit, intestinal or colorectal sensation, increased colonic bile acid concentration, and superficial colonic mucosal inflammation, as well as epithelial barrier dysfunction, neurohormonal up-regulation, and activation of secretory processes in the epithelial layer. Novel approaches to treatment include lifestyle modification, changes in diet, probiotics, and pharmacotherapy directed to the motility, sensation, and intraluminal milieu of patients with IBS. Despite recent advances, there is a need for development of new treatments to relieve pain in IBS without deleterious central or other adverse effects.
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Affiliation(s)
- Michael Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.) Program and Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN.
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9
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Peiris M, Aktar R, Raynel S, Hao Z, Mumphrey MB, Berthoud HR, Blackshaw LA. Effects of Obesity and Gastric Bypass Surgery on Nutrient Sensors, Endocrine Cells, and Mucosal Innervation of the Mouse Colon. Nutrients 2018; 10:E1529. [PMID: 30336615 PMCID: PMC6213226 DOI: 10.3390/nu10101529] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 10/09/2018] [Accepted: 10/10/2018] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Nutrient-sensing receptors located on enteroendocrine (EEC) cells modulate appetite via detection of luminal contents. Colonic 'tasting' of luminal contents may influence changes to appetite observed in obesity and after weight loss induced by bariatric surgery. We assessed the effects of obesity and gastric bypass-induced weight loss on expression of nutrient-sensing G-protein coupled receptors (GPCRs), EEC and enterochromaffin (EC) cells and mucosal innervation. METHODS qPCR and immunohistochemistry were used to study colonic tissue from (a) chow-fed/lean, (b) high-fat fed/obese, (c) Roux-en-Y gastric bypass surgery (RYGB), and (d) calorie restriction-induced weight loss mice. RESULTS Expression of GPR41, GPR43, GPR40, GPR120, GPR84, GPR119, GPR93 and T1R3 was increased in obese mice. Obesity-induced overexpression of GPR41, 40, 84, and 119 further increased after RYGB whereas GPR120 and T1R3 decreased. RYGB increased TGR5 expression. L-cells, but not EC cells, were increased after RYGB. No differences in mucosal innervation by protein gene product (PGP) 9.5 and GLP-1R-positive nerve fibers were observed. Stimulation of colonic mucosa with GPR41, GPR40, GPR85, GPR119, and TGR5 agonists increased cell activation marker expression. CONCLUSIONS Several nutrient-sensing receptors induced activation of colonic EEC. Profound adaptive changes to the expression of these receptors occur in response to diet and weight loss induced by RYGB or calorie restriction.
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Affiliation(s)
- Madusha Peiris
- Centre for Neuroscience & Trauma, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK.
| | - Rubina Aktar
- Centre for Neuroscience & Trauma, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK.
| | - Sarah Raynel
- Centre for Neuroscience & Trauma, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK.
| | - Zheng Hao
- Neurobiology of Nutrition & Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808, USA.
| | - Michael B Mumphrey
- Neurobiology of Nutrition & Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808, USA.
| | - Hans-Rudolf Berthoud
- Neurobiology of Nutrition & Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808, USA.
| | - L Ashley Blackshaw
- Centre for Neuroscience & Trauma, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK.
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10
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11
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Colitis-induced alterations in response properties of visceral nociceptive neurons in the rat caudal medulla oblongata and their modulation by 5-HT3 receptor blockade. Brain Res Bull 2018; 142:183-196. [PMID: 30031817 DOI: 10.1016/j.brainresbull.2018.07.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 06/15/2018] [Accepted: 07/17/2018] [Indexed: 12/17/2022]
Abstract
There is considerable clinical and experimental evidence that intestinal inflammation is associated with altered visceral nociceptive processing in the spinal cord and brain, but the underlying neuronal mechanisms, especially acting at the supraspinal level, remain unclear. Considering that the caudal ventrolateral medulla (CVLM) and the nucleus tractus solitarius (NTS) are the first sites for supraspinal processing of visceral pain signals, in the present study we evaluated the experimental colitis-induced changes in response properties of CVLM and NTS medullary neurons to noxious colorectal distension (CRD) in urethane-anesthetized adult male Wistar rats. To determine if gut inflammation alters the 5-HT3 receptor-dependent modulation of visceral pain-related CVLM and NTS cells, we examined the effects of intravenously administered selective 5-HT3 antagonist granisetron on ongoing and CRD-evoked activity of CVLM and NTS neurons in healthy control and colitic animals. In the absence of colonic pathology, the CVLM neurons were more excited by noxious CRD that the NTS cells, which demonstrated a greater tendency to be inhibited by the stimulation. The difference was eliminated after the development of colitis due to the increase in the proportion of CRD-excited neurons in both medullary regions associated with enhanced magnitude of the neuronal nociceptive responses. Intravenous granisetron (1 or 2 mg/kg) produced the dose-dependent suppression of the ongoing and evoked firing of CRD-excited cells within both the CVLM and NTS in normal conditions as well as was able to substantially reduce excitability of the caudal medullary neurons in the presence of colonic inflammation, arguing for the potential efficacy of the 5-HT3 receptor blockade with granisetron against both acute and inflammatory abdominal pain. Taken together, the data obtained can contribute to a deeper understanding of supraspinal serotonergic mechanisms responsible for the persistence of visceral hypersensitivity and hyperalgesia triggered by colonic inflammation.
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12
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Optogenetic Activation of Colon Epithelium of the Mouse Produces High-Frequency Bursting in Extrinsic Colon Afferents and Engages Visceromotor Responses. J Neurosci 2018; 38:5788-5798. [PMID: 29789376 DOI: 10.1523/jneurosci.0837-18.2018] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 05/14/2018] [Accepted: 05/16/2018] [Indexed: 12/30/2022] Open
Abstract
Epithelial cells of the colon provide a vital interface between the internal environment (lumen of the colon) and colon parenchyma. To examine epithelial-neuronal signaling at this interface, we analyzed mice in which channelrhodopsin (ChR2) was targeted to either TRPV1-positive afferents or to villin-expressing colon epithelial cells. Expression of a ChR2-EYFP fusion protein was directed to either primary sensory neurons or to colon epithelial cells by crossing Ai32 mice with TRPV1-Cre or villin-Cre mice, respectively. An ex vivo preparation of the colon was used for single-fiber analysis of colon sensory afferents of the pelvic nerve. Afferents were characterized using previously described criteria as mucosal, muscular, muscular-mucosal, or serosal and then tested for blue light-induced activation. Light activation of colon epithelial cells produced robust firing of action potentials, similar to that elicited by physiologic stimulation (e.g., circumferential stretch), in 50.5% of colon afferents of mice homozygous for ChR2 expression. Light-induced activity could be reduced or abolished in most fibers using a cocktail of purinergic receptor blockers suggesting ATP release by the epithelium contributed to generation of sensory neuron action potentials. Using electromyographic recording of visceromotor responses we found that light stimulation of the colon epithelium evoked behavioral responses in Vil-ChR2 mice that was similar to that seen with balloon distension of the colon. These ex vivo and in vivo data indicate that light stimulation of colon epithelial cells alone, without added mechanical or chemical stimuli, can directly activate colon afferents and elicit behavioral responses.SIGNIFICANCE STATEMENT Abdominal pain that accompanies inflammatory diseases of the bowel is particularly vexing because it can occur without obvious changes in the structure or inflammatory condition of the colon. Pain reflects abnormal sensory neuron activity that may be controlled in part by release of substances from lining epithelial cells. In support of this mechanism we determined that blue-light stimulation of channelrhodopsin-expressing colon epithelial cells could evoke action potential firing in sensory neurons and produce changes in measures of behavioral sensitivity. Thus, activity of colon epithelial cells alone, without added mechanical or chemical stimuli, is sufficient to activate pain-sensing neurons.
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13
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Contribution of membrane receptor signalling to chronic visceral pain. Int J Biochem Cell Biol 2018; 98:10-23. [DOI: 10.1016/j.biocel.2018.02.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 02/15/2018] [Accepted: 02/19/2018] [Indexed: 12/18/2022]
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Camilleri M, Ford AC. Pharmacotherapy for Irritable Bowel Syndrome. J Clin Med 2017; 6:E101. [PMID: 29077050 PMCID: PMC5704118 DOI: 10.3390/jcm6110101] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 10/23/2017] [Accepted: 10/24/2017] [Indexed: 12/11/2022] Open
Abstract
Irritable bowel syndrome (IBS) is a disorder of the brain-gut axis; the pathophysiological mechanisms include altered colonic motility, bile acid metabolism, neurohormonal regulation, immune dysfunction, alterations in the epithelial barrier and secretory properties of the gut. This article reviews the mechanisms, efficacy, and safety of current pharmacotherapy, and medications that are in phase III trials for the treatment of IBS. There remains a significant unmet need for effective treatments-particularly for the pain component of IBS-although the introduction of drugs directed at secretion, motility and a non-absorbable antibiotic provide options for the bowel dysfunction in IBS.
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Affiliation(s)
- Michael Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.) and Division of Gastroenterology and Hepatology, Mayo Clinic, 200 First Street S.W., Rochester, MN 55905, USA.
| | - Alexander C Ford
- Leeds Institute of Biomedical and Clinical Sciences, University of Leeds and Leeds Gastroenterology Institute, Leeds Teaching Hospitals Trust, Leeds LS9 7TF, UK.
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Kilinc E, Guerrero-Toro C, Zakharov A, Vitale C, Gubert-Olive M, Koroleva K, Timonina A, Luz LL, Shelukhina I, Giniatullina R, Tore F, Safronov BV, Giniatullin R. Serotonergic mechanisms of trigeminal meningeal nociception: Implications for migraine pain. Neuropharmacology 2016; 116:160-173. [PMID: 28025094 DOI: 10.1016/j.neuropharm.2016.12.024] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 12/02/2016] [Accepted: 12/22/2016] [Indexed: 10/20/2022]
Abstract
Serotonergic mechanisms play a central role in migraine pathology. However, the region-specific effects of serotonin (5-HT) mediated via multiple types of receptors in the nociceptive system are poorly understood. Using extracellular and patch-clamp recordings, we studied the action of 5-HT on the excitability of peripheral and central terminals of trigeminal afferents. 5-HT evoked long-lasting TTX-sensitive firing in the peripheral terminals of meningeal afferents, the origin site of migraine pain. Cluster analysis revealed that in majority of nociceptive fibers 5-HT induced either transient or persistent spiking activity with prevailing delta and theta rhythms. The 5-HT3-receptor antagonist MDL-72222 or 5-HT1B/D-receptor antagonist GR127935 largely reduced, but their combination completely prevented the excitatory pro-nociceptive action of 5-HT. The 5-HT3 agonist mCPBG activated spikes in MDL-72222-dependent manner but the 5HT-1 receptor agonist sumatriptan did not affect the nociceptive firing. 5-HT also triggered peripheral CGRP release in meninges, which was blocked by MDL-72222.5-HT evoked fast membrane currents and Ca2+ transients in a fraction of trigeminal neurons. Immunohistochemistry showed expression of 5-HT3A receptors in fibers innervating meninges. Endogenous release of 5-HT from degranulated mast cells increased nociceptive firing. Low pH but not histamine strongly activated firing. 5-HT reduced monosynaptic inputs from trigeminal Aδ- and C-afferents to the upper cervical lamina I neurons and this effect was blocked by MDL-72222. Consistent with central inhibitory effect, 5-HT reduced CGRP release in the brainstem slices. In conclusion, 5-HT evokes powerful pro-nociceptive peripheral and anti-nociceptive central effects in trigeminal system transmitting migraine pain.
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Affiliation(s)
- Erkan Kilinc
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland; Abant Izzet Baysal University, Medical Faculty, Department of Physiology, 14280, Bolu, Turkey.
| | - Cindy Guerrero-Toro
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland.
| | - Andrey Zakharov
- Laboratory of Neurobiology, Kazan Federal University, 420008, Kazan, Russia; Department of Physiology, Kazan State Medical University, 420012, Kazan, Russia.
| | - Carmela Vitale
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland.
| | - Max Gubert-Olive
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland.
| | - Ksenia Koroleva
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland; Laboratory of Neurobiology, Kazan Federal University, 420008, Kazan, Russia
| | - Arina Timonina
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland
| | - Liliana L Luz
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal.
| | - Irina Shelukhina
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland; Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, 117997, Moscow, Russia.
| | - Raisa Giniatullina
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland.
| | - Fatma Tore
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland; Biruni University, School of Medicine, 34010, Istanbul, Turkey.
| | - Boris V Safronov
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal; Neuronal Networks Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, 4200-135, Porto, Portugal.
| | - Rashid Giniatullin
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland; Laboratory of Neurobiology, Kazan Federal University, 420008, Kazan, Russia.
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Fuentes IM, Christianson JA. Ion channels, ion channel receptors, and visceral hypersensitivity in irritable bowel syndrome. Neurogastroenterol Motil 2016; 28:1613-1618. [PMID: 27781369 PMCID: PMC5123675 DOI: 10.1111/nmo.12979] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 09/23/2016] [Indexed: 12/20/2022]
Abstract
Ion channels are expressed throughout the gastrointestinal system and regulate nearly every aspect of digestion, including fluid secretion and absorption, motility, and visceral sensitivity. It is therefore not surprising that in the setting of functional bowel disorders, such as irritable bowel syndrome (IBS), ion channels are often altered in terms of expression level and function and are a target of pharmacological intervention. This is particularly true of their role in driving abdominal pain through visceral hypersensitivity (VH), which is the main reason IBS patients seek medical care. In the study by Scanzi et al., in the current issue of this journal, they provide evidence that the T-type voltage-gated calcium channel (Cav ) Cav 3.2 is upregulated in human IBS patients, and is necessary for the induction of an IBS-like disease state in mice. In this mini-review, we will discuss the contribution of specific ion channels to VH in IBS, both in human patients and rodent models. We will also discuss how Cav 3.2 may play a role as an integrator of multiple environmental stimuli contributing toward VH.
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Affiliation(s)
- I. M. Fuentes
- Department of Anatomy and Cell Biology; School of Medicine; University of Kansas Medical Center; Kansas City KS USA
| | - J. A. Christianson
- Department of Anatomy and Cell Biology; School of Medicine; University of Kansas Medical Center; Kansas City KS USA
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Lyubashina OA, Sivachenko IB, Panteleev SS, Nozdrachev AD. Effects of 5-HT3 receptor blockade on visceral nociceptive neurons in the ventrolateral reticular field of the rat medulla oblongata. J EVOL BIOCHEM PHYS+ 2016. [DOI: 10.1134/s0022093016040062] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Chen BN, Olsson C, Sharrad DF, Brookes SJH. Sensory innervation of the guinea pig colon and rectum compared using retrograde tracing and immunohistochemistry. Neurogastroenterol Motil 2016; 28:1306-16. [PMID: 27038370 DOI: 10.1111/nmo.12825] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 03/01/2016] [Indexed: 12/19/2022]
Abstract
BACKGROUND Neurons in lumbar and sacral dorsal root ganglia (DRG) comprise extrinsic sensory pathways to the distal colon and rectum, but their relative contributions are unclear. In this study, sensory innervation of the rectum and distal colon in the guinea pig was directly compared using retrograde labeling combined with immunohistochemistry. METHODS The lipophilic tracer, DiI, was injected in either the rectum or distal colon of anesthetized guinea pigs, then DRG (T6 to S5) and nodose ganglia were harvested and labeled using antisera for calcitonin gene-related peptide (CGRP) and transient receptor potential vanilloid 1(TRPV1). KEY RESULTS More primary afferent cell bodies were labeled from the rectum than from the distal colon. Vagal sensory neurons, with cell bodies in the nodose ganglia comprised fewer than 0.5% of labeled sensory neurons. Spinal afferents to the distal colon were nearly all located in thoracolumbar DRG, in a skewed unimodal distribution (peak at L2); fewer than 1% were located in sacral ganglia. In contrast, spinal afferents retrogradely labeled from the rectum had a bimodal distribution, with one peak at L3 and another at S2. Fewer than half of all retrogradely labeled spinal afferent neurons were immunoreactive for CGRP or TRPV1 and these included the larger traced neurons, especially in thoracolumbar ganglia. CONCLUSIONS & INFERENCES In the guinea pig, both the distal colon and the rectum receive a sensory innervation from thoracolumbar ganglia. Sacral afferents innervate the rectum but not the distal colon. Calcitonin gene-related peptide immunoreactivity was detectable in fewer than half of afferent neurons in both pathways.
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Affiliation(s)
- B N Chen
- Discipline of Human Physiology, FMST, School of Medicine, Flinders University, Bedford Park, SA, Australia
| | - C Olsson
- Department of Biological & Environmental Sciences, University of Göteborg, Göteborg, Sweden
| | - D F Sharrad
- Discipline of Human Physiology, FMST, School of Medicine, Flinders University, Bedford Park, SA, Australia
| | - S J H Brookes
- Discipline of Human Physiology, FMST, School of Medicine, Flinders University, Bedford Park, SA, Australia
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Keating C, Nocchi L, Yu Y, Donovan J, Grundy D. Ageing and gastrointestinal sensory function: altered colonic mechanosensory and chemosensory function in the aged mouse. J Physiol 2016; 594:4549-64. [PMID: 26592729 PMCID: PMC4983623 DOI: 10.1113/jp271403] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 11/13/2015] [Indexed: 01/13/2023] Open
Abstract
Key points Remarkably little is known about how age affects the sensory signalling pathways in the gastrointestinal tract despite age‐related gastrointestinal dysfunction being a prime cause of morbidity amongst the elderly population High‐threshold gastrointestinal sensory nerves play a key role in signalling distressing information from the gut to the brain. We found that ageing is associated with attenuated high‐threshold afferent mechanosensitivity in the murine colon, and associated loss of TRPV1 channel function. These units have the capacity to sensitise in response to injurious events, and their loss in ageing may predispose the elderly to lower awareness of GI injury or disease.
Abstract Ageing has a profound effect upon gastrointestinal function through mechanisms that are poorly understood. Here we investigated the effect of age upon gastrointestinal sensory signalling pathways in order to address the mechanisms underlying these changes. In vitro mouse colonic and jejunal preparations with attached splanchnic and mesenteric nerves were used to study mechanosensory and chemosensory afferent function in 3‐, 12‐ and 24‐month‐old C57BL/6 animals. Quantitative RT‐PCR was used to investigate mRNA expression in colonic tissue and dorsal root ganglion (DRG) cells isolated from 3‐ and 24‐month animals, and immunohistochemistry was used to quantify the number of 5‐HT‐expressing enterochromaffin (EC) cells. Colonic and jejunal afferent mechanosensory function was attenuated with age and these effects appeared earlier in the colon compared to the jejunum. Colonic age‐related loss of mechanosensory function was more pronounced in high‐threshold afferents compared to low‐threshold afferents. Chemosensory function was attenuated in the 24‐month colon, affecting TRPV1 and serotonergic signalling pathways. High‐threshold mechanosensory afferent fibres and small‐diameter DRG neurons possessed lower functional TRPV1 receptor responses, which occurred without a change in TRPV1 mRNA expression. Serotonergic signalling was attenuated at 24 months, but TPH1 and TPH2 mRNA expression was elevated in colonic tissue. In conclusion, we saw an age‐associated decrease in afferent mechanosensitivity in the mouse colon affecting HT units. These units have the capacity to sensitise in response to injurious events, and their loss in ageing may predispose the elderly to lower awareness of GI injury or disease. Remarkably little is known about how age affects the sensory signalling pathways in the gastrointestinal tract despite age‐related gastrointestinal dysfunction being a prime cause of morbidity amongst the elderly population High‐threshold gastrointestinal sensory nerves play a key role in signalling distressing information from the gut to the brain. We found that ageing is associated with attenuated high‐threshold afferent mechanosensitivity in the murine colon, and associated loss of TRPV1 channel function. These units have the capacity to sensitise in response to injurious events, and their loss in ageing may predispose the elderly to lower awareness of GI injury or disease.
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Affiliation(s)
- Christopher Keating
- Department of Biomedical Sciences, University of Sheffield, Sheffield, UK.,Department of Pharmacy, Pharmacology and Postgraduate Medicine, University of Hertfordshire, Hatfield, Hertfordshire, UK
| | - Linda Nocchi
- Department of Biomedical Sciences, University of Sheffield, Sheffield, UK
| | - Yang Yu
- Department of Biomedical Sciences, University of Sheffield, Sheffield, UK
| | - Jemma Donovan
- Department of Biomedical Sciences, University of Sheffield, Sheffield, UK
| | - David Grundy
- Department of Biomedical Sciences, University of Sheffield, Sheffield, UK
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20
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Halliez MCM, Buret AG. Gastrointestinal Parasites and the Neural Control of Gut Functions. Front Cell Neurosci 2015; 9:452. [PMID: 26635531 PMCID: PMC4658430 DOI: 10.3389/fncel.2015.00452] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/02/2015] [Indexed: 12/30/2022] Open
Abstract
Gastrointestinal motility and transport of water and electrolytes play key roles in the pathophysiology of diarrhea upon exposure to enteric parasites. These processes are actively modulated by the enteric nervous system (ENS), which includes efferent, and afferent neurons, as well as interneurons. ENS integrity is essential to the maintenance of homeostatic gut responses. A number of gastrointestinal parasites are known to cause disease by altering the ENS. The mechanisms remain incompletely understood. Cryptosporidium parvum, Giardia duodenalis (syn. Giardia intestinalis, Giardia lamblia), Trypanosoma cruzi, Schistosoma species and others alter gastrointestinal motility, absorption, or secretion at least in part via effects on the ENS. Recent findings also implicate enteric parasites such as C. parvum and G. duodenalis in the development of post-infectious complications such as irritable bowel syndrome, which further underscores their effects on the gut-brain axis. This article critically reviews recent advances and the current state of knowledge on the impact of enteric parasitism on the neural control of gut functions, and provides insights into mechanisms underlying these abnormalities.
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Affiliation(s)
- Marie C M Halliez
- Department of Biological Sciences, Inflammation Research Network, Host-Parasite Interaction NSERC-CREATE, University of Calgary Calgary, AB, Canada ; Protozooses transmises par l'alimentation, Rouen University Hospital, University of Rouen and Institute for Biomedical Research, University of Reims Champagne-Ardennes Rouen and Reims, France
| | - André G Buret
- Department of Biological Sciences, Inflammation Research Network, Host-Parasite Interaction NSERC-CREATE, University of Calgary Calgary, AB, Canada
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21
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Brumovsky PR, La JH, Gebhart GF. Distribution across tissue layers of extrinsic nerves innervating the mouse colorectum - an in vitro anterograde tracing study. Neurogastroenterol Motil 2014; 26:1494-507. [PMID: 25185752 PMCID: PMC4200533 DOI: 10.1111/nmo.12419] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 07/27/2014] [Indexed: 01/16/2023]
Abstract
BACKGROUND Anterograde in vitro tracing of the pelvic nerve (PN) and visualization in the horizontal plane in whole mount preparations has been fundamental in the analysis of distribution of peripheral nerves innervating the colorectum. Here, we performed a similar analysis, but in cryostat sections of the mouse colorectum, allowing for a more direct visualization of nerve distribution in all tissue layers. METHODS Colorectum with attached PNs was dissected from adult male BalbC mice. Presence of active afferents was certified by single fiber recording of fine PN fibers. This was followed by 'bulk' (all fibers) anterograde tracing using biotinamide (BTA). Histo- and immunohistochemical techniques were used for visualization of BTA-positive nerves, and evaluation of co-localization with calcitonin gene-related peptide (CGRP), respectively. Tissue was analyzed using confocal microscopy on transverse or longitudinal colorectum sections. KEY RESULTS Abundant BTA-positive nerves spanning all layers of the mouse colorectum and contacting myenteric plexus neurons, distributing within the muscle layer, penetrating deeper into the organ and contacting blood vessels, submucosal plexus neurons or even penetrating the mucosa, were regularly detected. Several traced axons co-localized CGRP, supporting their afferent nature. Finally, anterograde tracing of the PN also exposed abundant BTA-positive nerves in the major pelvic ganglion. CONCLUSIONS & INFERENCES We present the patterns of innervation of extrinsic axons across layers in the mouse colorectum, including the labile mucosal layer. The proposed approach could also be useful in the analysis of associations between morphology and physiology of peripheral nerves targeting the different layers of the colorectum.
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Affiliation(s)
- Pablo R. Brumovsky
- School of Biomedical Sciences, Austral University, Pilar 1629, Buenos Aires, Argentina,CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas), Buenos Aires, Argentina,Pittsburgh Center for Pain Research, Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA 15213
| | - Jun-Ho La
- Pittsburgh Center for Pain Research, Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA 15213
| | - G. F. Gebhart
- Pittsburgh Center for Pain Research, Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA 15213
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Takahashi T. Interdigestive migrating motor complex -its mechanism and clinical importance. J Smooth Muscle Res 2014; 49:99-111. [PMID: 24662475 PMCID: PMC5137267 DOI: 10.1540/jsmr.49.99] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Migrating motor complex (MMC) is well characterized by the appearance of gastrointestinal
(GI) contractions in the interdigestive state. The physiological importance of gastric MMC
is a mechanical and chemical cleansing of the empty stomach in preparation for the next
meal. MMC cycle is mediated via the interaction between motilin and 5-hydroxytryptamine
(5-HT) by the positive feedback mechanism in conscious dogs. Luminal administration of
5-HT initiates duodenal phase II and phase III with a concomitant increase of plasma
motilin release. Duodenal 5-HT concentration is increased during gastric phase II and
phase III. Intravenous infusion of motilin increases luminal 5-HT content and induces
phase III. 5-HT4 antagonists significantly inhibit both of gastric and
intestinal phase III, while 5-HT3 antagonists inhibit only gastric phase III.
These suggest that gastric MMC is regulated via vagus, 5-HT3/4 receptors and
motilin, while intestinal MMC is regulated via intrinsic primary afferent neurons (IPAN)
and 5-HT4 receptors. We propose the possibility that maximally released motilin
by a positive feedback depletes 5-HT granules in the duodenal EC cells, resulting in no
more contractions. Stress is highly associated with the pathogenesis of functional
dyspepsia (FD). Acoustic stress attenuates gastric phase III without affecting intestinal
phase III in conscious dogs, via reduced vagal activity. Subset of FD patients shows
reduced vagal activity and impaired gastric phase III. The impaired gastric MMC may
aggravate dyspeptic symptoms following a food ingestion. Maintaining MMC cycle in the
interdigestive state is an important factor to prevent the postprandial dyspeptic
symptoms.
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Affiliation(s)
- Toku Takahashi
- Department of Surgery and Department of Neurology, Medical College of Wisconsin and Zablocki VA Medical Center, Milwaukee, Wisconsin, USA
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23
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Grover M, Camilleri M. Ramosetron in irritable bowel syndrome with diarrhea: new hope or the same old story? Clin Gastroenterol Hepatol 2014; 12:960-2. [PMID: 24393804 PMCID: PMC4032610 DOI: 10.1016/j.cgh.2013.12.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 12/18/2013] [Indexed: 02/07/2023]
Affiliation(s)
- Madhusudan Grover
- Clinical Enteric Neuroscience Translational and Epidemiological Research, Mayo Clinic, Rochester, Minnesota
| | - Michael Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research, Mayo Clinic, Rochester, Minnesota
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Matricon J, Muller E, Accarie A, Meleine M, Etienne M, Voilley N, Busserolles J, Eschalier A, Lazdunski M, Bourdu S, Gelot A, Ardid D. Peripheral contribution of NGF and ASIC1a to colonic hypersensitivity in a rat model of irritable bowel syndrome. Neurogastroenterol Motil 2013; 25:e740-54. [PMID: 23902154 DOI: 10.1111/nmo.12199] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 07/08/2013] [Indexed: 12/11/2022]
Abstract
BACKGROUND Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder associated with idiopathic colonic hypersensitivity (CHS). However, recent studies suggest that low-grade inflammation could underlie CHS in IBS. The pro-inflammatory mediator nerve growth factor (NGF) plays a key role in the sensitization of peripheral pain pathways and several studies have reported its contribution to visceral pain development. NGF modulates the expression of Acid-Sensing Ion Channels (ASICs), which are proton sensors involved in sensory neurons sensitization. This study examined the peripheral contribution of NGF and ASICs to IBS-like CHS induced by butyrate enemas in the rat colon. METHODS Colorectal distension and immunohistochemical staining of sensory neurons were used to evaluate NGF and ASICs contribution to the development of butyrate-induced CHS. KEY RESULTS Systemic injection of anti-NGF antibodies or the ASICs inhibitor amiloride prevented the development of butyrate-induced CHS. A significant increase in NGF and ASIC1a protein expression levels was observed in sensory neurons of rats displaying butyrate-induced CHS. This increase was specific of small- and medium-diameter L1 + S1 sensory neurons, where ASIC1a was co-expressed with NGF or trkA in CGRP-immunoreactive somas. ASIC1a was also overexpressed in retrogradely labeled colon sensory neurons. Interestingly, anti-NGF antibody administration prevented ASIC1a overexpression in sensory neurons of butyrate-treated rats. CONCLUSIONS & INFERENCES Our data suggest that peripheral NGF and ASIC1a concomitantly contribute to the development of butyrate-induced CHS NGF-ASIC1a interplay may have a pivotal role in the sensitization of colonic sensory neurons and as such, could be considered as a potential new therapeutic target for IBS treatment.
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Affiliation(s)
- J Matricon
- NEURO-DOL, Pharmacologie Fondamentale et Clinique de la Douleur, Faculté de Médecine, INSERM/UdA, UMR 1107, Université d'Auvergne, Clermont-Ferrand, France
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Page C, Humphrey P. Sir David Jack: an extraordinary drug discoverer and developer. Br J Clin Pharmacol 2013; 75:1213-8. [PMID: 22994263 DOI: 10.1111/j.1365-2125.2012.04467.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Affiliation(s)
- Clive Page
- Sackler Institute of Pulmonary Pharmacology, Institute of Pharmaceutical Science, King's College London, London, UK
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Laycock H, Valente J, Bantel C, Nagy I. Peripheral mechanisms of burn injury-associated pain. Eur J Pharmacol 2013; 716:169-78. [DOI: 10.1016/j.ejphar.2013.01.071] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 01/22/2013] [Accepted: 01/29/2013] [Indexed: 12/12/2022]
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Abstract
Serotonin (5-HT) has been recognized for decades as an important signalling molecule in the gut, but it is still revealing its secrets. Novel gastrointestinal functions of 5-HT continue to be discovered, as well as distant actions of gut-derived 5-HT, and we are learning how 5-HT signalling is altered in gastrointestinal disorders. Conventional functions of 5-HT involving intrinsic reflexes include stimulation of propulsive and segmentation motility patterns, epithelial secretion and vasodilation. Activation of extrinsic vagal and spinal afferent fibres results in slowed gastric emptying, pancreatic secretion, satiation, pain and discomfort, as well as nausea and vomiting. Within the gut, 5-HT also exerts nonconventional actions such as promoting inflammation and serving as a trophic factor to promote the development and maintenance of neurons and interstitial cells of Cajal. Platelet 5-HT, originating in the gut, promotes haemostasis, influences bone development and serves many other functions. 5-HT3 receptor antagonists and 5-HT4 receptor agonists have been used to treat functional disorders with diarrhoea or constipation, respectively, and the synthetic enzyme tryptophan hydroxylase has also been targeted. Emerging evidence suggests that exploiting epithelial targets with nonabsorbable serotonergic agents could provide safe and effective therapies. We provide an overview of these serotonergic actions and treatment strategies.
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Galligan JJ, Patel BA, Schneider SP, Wang H, Zhao H, Novotny M, Bian X, Kabeer R, Fried D, Swain GM. Visceral hypersensitivity in female but not in male serotonin transporter knockout rats. Neurogastroenterol Motil 2013; 25:e373-81. [PMID: 23594365 DOI: 10.1111/nmo.12133] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Accepted: 03/11/2013] [Indexed: 12/15/2022]
Abstract
BACKGROUND Visceral hypersensitivity occurs in irritable bowel syndrome (IBS), particularly in women. Serotonin signaling, including reduced serotonin transporter (SERT) expression, may be disrupted in IBS patients. We studied SERT gene knockout (KO) rats to determine if they exhibited sex-related alterations in visceral sensitivity. METHODS We measured serotonin in the colonic mucosa using HPLC and amperometric microelectrode techniques. Visceral sensitivity was assessed using the electromyographic visceromotor response (VMR) in response to colorectal balloon distention (CRD). We studied the electrophysiologic properties of colon projecting sensory neurons in vitro using whole-cell recordings. KEY RESULTS Mucosal serotonin levels were not different among male and female WT and SERT KO rats. Serotonin oxidation currents in vitro were larger (P < 0.05) in tissues from male and female SERT KO compared with WT rats. Oxidation currents in male and female WT, but not SERT KO, rats were increased (P < 0.05) by the SERT inhibitor fluoxetine (1 μmol L(-1) ). The VMR to CRD was increased in female but not in male SERT KO rats (P < 0.05); this response varied with the estrous cycle. Colon projecting sensory neurons from female SERT KO rats fired more action potentials compared with neurons from female WT rats. There were no differences in action potential firing in neurons from male WT and SERT KO rats. CONCLUSIONS & INFERENCES Increased colonic extracellular serotonin in female SERT KO rats is associated with visceral hypersensitivity and hyperexcitability of colon projecting sensory neurons. The SERT KO rat is a model for studying interactions between serotonin, sex and visceral sensation.
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Affiliation(s)
- J J Galligan
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA.
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Abstract
Visceral sensory neurons activate reflex pathways that control gut function and also give rise to important sensations, such as fullness, bloating, nausea, discomfort, urgency and pain. Sensory neurons are organised into three distinct anatomical pathways to the central nervous system (vagal, thoracolumbar and lumbosacral). Although remarkable progress has been made in characterizing the roles of many ion channels, receptors and second messengers in visceral sensory neurons, the basic aim of understanding how many classes there are, and how they differ, has proven difficult to achieve. We suggest that just five structurally distinct types of sensory endings are present in the gut wall that account for essentially all of the primary afferent neurons in the three pathways. Each of these five major structural types of endings seems to show distinctive combinations of physiological responses. These types are: 'intraganglionic laminar' endings in myenteric ganglia; 'mucosal' endings located in the subepithelial layer; 'muscular-mucosal' afferents, with mechanosensitive endings close to the muscularis mucosae; 'intramuscular' endings, with endings within the smooth muscle layers; and 'vascular' afferents, with sensitive endings primarily on blood vessels. 'Silent' afferents might be a subset of inexcitable 'vascular' afferents, which can be switched on by inflammatory mediators. Extrinsic sensory neurons comprise an attractive focus for targeted therapeutic intervention in a range of gastrointestinal disorders.
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Brookes SJH, Spencer NJ, Costa M, Zagorodnyuk VP. Extrinsic primary afferent signalling in the gut. NATURE REVIEWS. GASTROENTEROLOGY & HEPATOLOGY 2013. [PMID: 23438947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
Visceral sensory neurons activate reflex pathways that control gut function and also give rise to important sensations, such as fullness, bloating, nausea, discomfort, urgency and pain. Sensory neurons are organised into three distinct anatomical pathways to the central nervous system (vagal, thoracolumbar and lumbosacral). Although remarkable progress has been made in characterizing the roles of many ion channels, receptors and second messengers in visceral sensory neurons, the basic aim of understanding how many classes there are, and how they differ, has proven difficult to achieve. We suggest that just five structurally distinct types of sensory endings are present in the gut wall that account for essentially all of the primary afferent neurons in the three pathways. Each of these five major structural types of endings seems to show distinctive combinations of physiological responses. These types are: 'intraganglionic laminar' endings in myenteric ganglia; 'mucosal' endings located in the subepithelial layer; 'muscular-mucosal' afferents, with mechanosensitive endings close to the muscularis mucosae; 'intramuscular' endings, with endings within the smooth muscle layers; and 'vascular' afferents, with sensitive endings primarily on blood vessels. 'Silent' afferents might be a subset of inexcitable 'vascular' afferents, which can be switched on by inflammatory mediators. Extrinsic sensory neurons comprise an attractive focus for targeted therapeutic intervention in a range of gastrointestinal disorders.
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Affiliation(s)
- Simon J H Brookes
- Centre for Neuroscience and Discipline of Human Physiology, Flinders Medical Science and Technology, Flinders University, Sturt Road, Bedford Park, SA 5042, Australia.
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Xue B, Müller MH, Li J, Pesch T, Kasparek MS, Sibaev A, Hausmann M, Rogler G, Kreis ME. Mast cells and the cyclooxygenase pathway mediate colonic afferent nerve sensitization in a murine colitis model. Auton Neurosci 2013; 174:47-53. [PMID: 23384476 DOI: 10.1016/j.autneu.2013.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2012] [Revised: 12/16/2012] [Accepted: 01/01/2013] [Indexed: 01/25/2023]
Abstract
INTRODUCTION Intestinal inflammation alters colonic afferent nerve sensitivity which may contribute to patients' perception of abdominal discomfort. We aimed to explore whether mast cells and the cyclooxygenase pathway are involved in altered afferent nerve sensitivity during colitis. METHODS C57Bl6 mice received 3% dextran-sulfate sodium (DSS) in drinking water for 7 days to induce colitis. Control animals received regular water. On day 8 inflammation was assessed in the proximal colon by morphology and histology. Extracellular afferent nerve discharge was recorded from the mesenteric nerve of a 2 cm colonic segment. Subgroups were treated in vitro with the mast cell stabilizer doxantrazole (10⁻⁴M) or the cyclooxygenase inhibitor naproxen (10⁻⁵M). RESULTS DSS colitis resulted in morphological and histological signs of inflammation. At baseline, peak firing was 11±2 imp s⁻¹ in colitis segments and 5±1 imp s⁻¹ in uninflamed control segments (p<0.05; mean ± SEM; each n=6). In colitis segments, afferent nerve discharge to bradykinin (0.5 μM) was increased to 47±7 compared to 23±6 imp s⁻¹ in recordings from non-inflamed control tissue (p<0.05). Mechanosensitivity during luminal ramp distension (0-80 cm H₂O) was increased reaching 24±5 imp s⁻¹ at 80 cm H₂O during colitis compared to 14±2 in non-inflamed controls (p<0.05). Doxantrazole or naproxen reduced afferent discharge to bradykinin and luminal ramp distension in colitis segments to control levels. CONCLUSION Intestinal inflammation sensitizes mesenteric afferent nerve fibers to bradykinin and mechanical stimuli. The underlying mechanism responsible for this sensitization seems to involve mast cells and prostaglandins.
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Affiliation(s)
- B Xue
- Department of Pathophysiology, Shandong University, Medical School, Shandong, China
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Takahashi T. Mechanism of interdigestive migrating motor complex. J Neurogastroenterol Motil 2012; 18:246-57. [PMID: 22837872 PMCID: PMC3400812 DOI: 10.5056/jnm.2012.18.3.246] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 05/13/2012] [Accepted: 05/23/2012] [Indexed: 12/15/2022] Open
Abstract
Migrating motor complex (MMC) is well characterized by the appearance of gastrointestinal contractions in the interdigestive state. This review article discussed the mechanism of gastrointestinal MMC. Luminal administration of 5-hydroxytryptamine (5-HT) initiates duodenal phase II followed by gastrointestinal phase III with a concomitant increase of plasma motilin release in conscious dogs. Duodenal 5-HT concentration is increased during gastric phase II and phase III. Intravenous infusion of motilin increases luminal 5-HT content and induces gastrointestinal phase III. 5-HT(4) antagonists significantly inhibits both of gastric and intestinal phase III, while 5-HT(3) antagonists inhibited only gastric phase III. These suggest that gastrointestinal MMC cycle is mediated via the interaction between motilin and 5-HT by the positive feedback mechanism. Gastric MMC is regulated via vagus, 5-HT(3/4) receptors and motilin, while intestinal MMC is regulated via intrinsic primary afferent neurons and 5-HT(4) receptors. Stress is highly associated with the pathogenesis of functional dyspepsia. Acoustic stress attenuates gastric phase III without affecting intestinal phase III in conscious dogs, via reduced vagal activity and increased sympathetic activity. It has been shown that subset of functional dyspepsia patients show reduced vagal activity and impaired gastric phase III. The physiological importance of gastric MMC is a mechanical and chemical cleansing of the empty stomach in preparation for the next meal. The impaired gastric MMC may aggravate dyspeptic symptoms following a food ingestion. Thus, maintaining gastric MMC in the interdigestive state is an important factor to prevent the postprandial dyspeptic symptoms.
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Affiliation(s)
- Toku Takahashi
- Department of Surgery, Medical College of Wisconsin and Zablocki VA Medical Center, Milwaukee, Wisconsin, USA
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Gribovskaja-Rupp I, Takahashi T, Ridolfi T, Kosinski L, Ludwig K. Upregulation of mucosal 5-HT3 receptors is involved in restoration of colonic transit after pelvic nerve transection. Neurogastroenterol Motil 2012; 24:472-8, e218. [PMID: 22304456 DOI: 10.1111/j.1365-2982.2012.01890.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Colonic dysfunction occurs after pelvic autonomic nerve damage. The enteric nervous system can compensate. We investigated the role of mucosal serotonin receptors, 5-HT(3) and 5-HT(4) , in the colonic motility restoration over 2 weeks after parasympathetic pelvic nerve transection in a rat model. METHODS Male Sprague-Dawley rats underwent pelvic nerve transection or sham operation. Colonic transit was expressed as the geometric center of (51) Cr distribution. Mucosal 5-HT(3) and 5-HT(4) receptor expression was evaluated by Western blot. Intraluminal pressure increase was measured after 5-HT(3) (ondansetron) or 5-HT(4) receptor antagonist (GR125487) administration in vitro in sham and denervated distal colons. KEY RESULTS At 2 weeks, colonic transit in the denervated group was 30% slower compared to the sham group (P < 0.01). At 1 and 2 weeks, 5-HT(3) receptor expression was increased two-fold in the denervated group, compared to shams (P < 0.05). A three-fold smaller dose of ondansetron was required in denervated tissues to inhibit intraluminal pressure rise than in sham colons (P < 0.01). There was no difference in the expression of 5-HT(4) receptor or the response to GR125487 in denervated vs sham colons. CONCLUSIONS & INFERENCES Colonic motility was restored to approximately 70% normal over 1 week without further improvement at 2 weeks. Enteric nervous system compensated by upregulating mucosal 5-HT(3,) but not 5-HT(4,) receptors.
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Affiliation(s)
- I Gribovskaja-Rupp
- Department of Surgery, Medical College of Wisconsin, Clement J Zablocki VA Medical Center, Milwaukee, WI, USA
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Digestive System, Liver, and Abdominal Cavity. THE CAT 2012. [PMCID: PMC7158306 DOI: 10.1016/b978-1-4377-0660-4.00023-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Barbara G, Cremon C, De Giorgio R, Dothel G, Zecchi L, Bellacosa L, Carini G, Stanghellini V, Corinaldesi R. Mechanisms underlying visceral hypersensitivity in irritable bowel syndrome. Curr Gastroenterol Rep 2011; 13:308-15. [PMID: 21537962 DOI: 10.1007/s11894-011-0195-7] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Visceral hypersensitivity is currently considered a key pathophysiological mechanism involved in pain perception in large subgroups of patients with functional gastrointestinal disorders, including irritable bowel syndrome (IBS). In IBS, visceral hypersensitivity has been described in 20%-90% of patients. The contribution of the central nervous system and psychological factors to visceral hypersensitivity in patients with IBS may be significant, although still debated. Peripheral factors have gained increasing attention following the recognition that infectious enteritis may trigger the development of persistent IBS symptoms, and the identification of mucosal immune, neural, endocrine, microbiological, and intestinal permeability abnormalities. Growing evidence suggests that these factors play an important role in pain transmission from the periphery to the brain via sensory nerve pathways in large subsets of patients with IBS. In this review, we will report on recent data on mechanisms involved in visceral hypersensitivity in IBS, with particular attention paid to peripheral mechanisms.
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Affiliation(s)
- Giovanni Barbara
- Department of Clinical Medicine and Center for Applied Biomedical Research, University of Bologna, Bologna, Italy.
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Camilleri M. LX-1031, a tryptophan 5-hydroxylase inhibitor, and its potential in chronic diarrhea associated with increased serotonin. Neurogastroenterol Motil 2011; 23:193-200. [PMID: 21159063 PMCID: PMC3076306 DOI: 10.1111/j.1365-2982.2010.01643.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
LX-1031 is an oral, small molecule tryptophan 5-hydroxylase (TPH) inhibitor that reduces serotonin (5-HT) synthesis peripherally. It has potential for illnesses characterized by excess 5-HT, such as diarrhea-predominant irritable bowel syndrome (IBS-D) and carcinoid diarrhea. In vitro, inhibition of TPH1 occurred in 10(-8) -10(-7) mol L(-1) range. In vivo in rodents, LX-1031 has no effect on brain 5-HT while dose-dependently reducing 5-HT, particularly in the small bowel. After oral LX1031 in humans, systemic exposure is very low, plasma concentrations are linear in dose range 250-750 mg q.i.d.; the median T(1/2) for elimination is ∼ 20 h, and repeat administration for 14 days doubles C(max) . In ascending-single-dose and multiple-dose (14 days) trials in healthy volunteers, LX-1031, 2-4 g day(-1) significantly reduced urinary 5-hydroxyindoleacetic acid (5-HIAA) starting by Day 5, and persisting over the 14 day exposure. There are no dose-limiting toxicities in healthy subjects or remarkable adverse effects in clinical trials to date. Over a 28-day treatment period, LX-1031 was associated with improved weekly global scores (2/4 weeks) and improved stool consistency with lower urinary 5-HIAA excretion. LX-1031 appears promising for chronic diarrhea associated with increased 5-HT expression including IBS-D. Optimal doses, efficacy and safety in IBS clinical trials need to be fully elucidated; low systemic exposure, selectivity for TPH1 over TPH2, and lack of effect on brain 5-HT in several species suggest that LX-1031 is unlikely to cause affective disorders.
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Affiliation(s)
- Michael Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, Minnesota, U.S.A
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Hansen MB, Wallin L, Husebye E, Dommergaard L, Gregersen H. Migrating Motor Complex in Colectomized Ileo Stoma Patients. Basic Clin Pharmacol Toxicol 2011; 108:349-58. [DOI: 10.1111/j.1742-7843.2010.00665.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Tong W, Kamiyama Y, Ridolfi TJ, Zietlow A, Zheng J, Kosinski L, Ludwig K, Takahashi T. The role of 5-HT3 and 5-HT4 receptors in the adaptive mechanism of colonic transit following the parasympathetic denervation in rats. J Surg Res 2010; 171:510-6. [PMID: 20691988 DOI: 10.1016/j.jss.2010.05.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 04/20/2010] [Accepted: 05/04/2010] [Indexed: 12/20/2022]
Abstract
BACKGROUND Clinical studies show that disturbed colonic motility induced by extrinsic nerves damage is restored over time. We studied whether 5-HT3 and 5HT4 receptors are involved in mediating the adaptive mechanisms following parasympathetic denervation. METHODS Parasympathetic denervation of the entire colon was achieved by bilateral pelvic nerve transection and truncal vagotomy in rats. Colonic transit was measured by calculating the geometric center (GC) of 51Cr distribution. Expression of 5-HT3 and 5HT4 receptor mRNA was determined by real time RT-PCR. RESULTS Parasympathetic denervation caused a significant delay in colonic transit (GC=4.36) at postoperative day (POD) 1, compared with sham operation (GC=6.31). Delayed transit was gradually restored by POD 7 (GC=5.99) after the denervation. Restored colonic transit was antagonized by the administration of 5-HT3 and 5HT4 receptors antagonists at POD 7. 5-HT3 and 5HT4 receptors mRNA expression were significantly increased in the mucosal/submucosal layer at POD 3 or POD 7, whereas no significant difference was observed in the longitudinal muscle layers adherent with the myenteric plexus (LMMP). CONCLUSIONS It is suggested that up-regulation of 5-HT3 and 5-HT4 receptors expression in the mucosal/submucosal layer is involved to restore the delayed transit after the parasympathetic denervation in rats.
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Affiliation(s)
- Weidong Tong
- Department of Surgery, Medical College of Wisconsin and Zablocki VA Medical Center, Milwaukee, Wisconsin 53295, USA
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Tong W, Kamiyama Y, Ridolfi TJ, Zietlow A, Zheng J, Kosinski L, Ludwig K, Takahashi T. The role of 5-HT3 and 5-HT4 receptors in the adaptive mechanism of colonic transit following the parasympathetic denervation in rats. THE JOURNAL OF SURGICAL RESEARCH 2010. [PMID: 20691988 DOI: 10.1016/j.jss] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Clinical studies show that disturbed colonic motility induced by extrinsic nerves damage is restored over time. We studied whether 5-HT3 and 5HT4 receptors are involved in mediating the adaptive mechanisms following parasympathetic denervation. METHODS Parasympathetic denervation of the entire colon was achieved by bilateral pelvic nerve transection and truncal vagotomy in rats. Colonic transit was measured by calculating the geometric center (GC) of 51Cr distribution. Expression of 5-HT3 and 5HT4 receptor mRNA was determined by real time RT-PCR. RESULTS Parasympathetic denervation caused a significant delay in colonic transit (GC=4.36) at postoperative day (POD) 1, compared with sham operation (GC=6.31). Delayed transit was gradually restored by POD 7 (GC=5.99) after the denervation. Restored colonic transit was antagonized by the administration of 5-HT3 and 5HT4 receptors antagonists at POD 7. 5-HT3 and 5HT4 receptors mRNA expression were significantly increased in the mucosal/submucosal layer at POD 3 or POD 7, whereas no significant difference was observed in the longitudinal muscle layers adherent with the myenteric plexus (LMMP). CONCLUSIONS It is suggested that up-regulation of 5-HT3 and 5-HT4 receptors expression in the mucosal/submucosal layer is involved to restore the delayed transit after the parasympathetic denervation in rats.
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Affiliation(s)
- Weidong Tong
- Department of Surgery, Medical College of Wisconsin and Zablocki VA Medical Center, Milwaukee, Wisconsin 53295, USA
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Yang N, Liu SM, Zheng LF, Ji T, Li Y, Mi XL, Xue H, Ren W, Xu JD, Zhang XH, Li LS, Zhang Y, Zhu JX. Activation of submucosal 5-HT(3) receptors elicits a somatostatin-dependent inhibition of ion secretion in rat colon. Br J Pharmacol 2010; 159:1623-5. [PMID: 20233224 DOI: 10.1111/j.1476-5381.2010.00653.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND AND PURPOSE 5-Hydroxytryptamine (5-HT) is a key regulator of the gastrointestinal system and we have shown that submucosal neuronal 5-HT(3) receptors exerted a novel inhibitory effect on colonic ion transport. The aim of the present study was to investigate the precise mechanism(s) underlying this inhibitory effect. EXPERIMENTAL APPROACH Mucosa/submucosa or mucosa-only preparations from rat distal colon were mounted in Ussing chambers for measurement of short-circuit current (I(sc)) as an indicator of ion secretion. Somatostatin release was determined with radioimmunoassay. Intracellular cAMP content was measured with enzyme-linked immunoadsorbent assay (elisa). Immunohistochemical techniques were used to study the expression of 5-HT(3) receptors, somatostatin and somatostatin receptors in colonic tissue. KEY RESULTS In rat distal colonic mucosa/submucosa preparations, pretreatment with 5-HT(3) receptor antagonists enhanced 5-HT-induced increases in I(sc). However, in mucosa-only preparations without retained neural elements, pretreatment with 5-HT(3) receptor antagonists inhibited 5-HT-induced DeltaI(sc). Pretreatment with a somatostatin-2 (sst(2)) receptor antagonist in mucosa/submucosa preparations augmented 5-HT-induced DeltaI(sc). Combination of sst(2) and 5-HT(3) receptor antagonists did not cause further enhancement of 5-HT-induced DeltaI(sc). Moreover, both sst(2) and 5-HT(3) receptor antagonists enhanced 5-HT-induced increase in intracellular cAMP concentration in the mucosa/submucosa preparations. 5-HT released somatostatin from rat colonic mucosa/submucosa preparations, an effect prevented by pretreatment with 5-HT(3) receptor antagonists. Immunohistochemical staining demonstrated the presence of 5-HT(3) receptors on submucosal somatostatin neurons and of sst(2) receptors on colonic mucosa. CONCLUSION AND IMPLICATIONS Activation of neuronal 5-HT(3) receptors in the submucosal plexus of rat colon suppressed 5-HT-induced ion secretion by releasing somatostatin from submucosal neurons.
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Affiliation(s)
- N Yang
- Department of Physiology, Capital Medical University, Beijing, China
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Camilleri M, Andresen V. Current and novel therapeutic options for irritable bowel syndrome management. Dig Liver Dis 2009; 41:854-62. [PMID: 19665953 PMCID: PMC2783342 DOI: 10.1016/j.dld.2009.07.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 07/13/2009] [Indexed: 02/07/2023]
Abstract
Irritable bowel syndrome is a functional gastrointestinal disorder affecting up to 3-15% of the general population in western countries. It is characterised by unexplained abdominal pain, discomfort, and bloating in association with altered bowel habits. The pathophysiology of irritable bowel syndrome is multifactorial involving disturbances of the brain-gut axis. The pathophysiology provides the rationale for pharmacotherapy: abnormal gastrointestinal motor functions, visceral hypersensitivity, psychosocial factors, autonomic dysfunction, and mucosal immune activation. Understanding the mechanisms, and their mediators or modulators including neurotransmitters and receptors have led to several therapeutic approaches including agents acting on the serotonin receptor or serotonin transporter system, antidepressants, novel selective anticholinergics, alpha-adrenergic agonists, opioid agents, cholecystokinin-antagonists, neurokinin-antagonists, somatostatin receptor agonists, corticotropin releasing factor antagonists, chloride channel activators, guanylate cyclase-c agonists, melatonin, atypical benzodiazepines, antibiotics, immune modulators and probiotics. The mechanisms and current evidence regarding efficacy of these agents are reviewed.
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Affiliation(s)
- M Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research, College of Medicine, Mayo Clinic, Charlton 8-110, 200 First St SW, Rochester, MN 55905, United States.
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Liu HR, Wang XM, Zhou EH, Shi Y, Li N, Yuan LS, Wu HG. Acupuncture at both ST25 and ST37 improves the pain threshold of chronic visceral hypersensitivity rats. Neurochem Res 2009; 34:1914-8. [PMID: 19387829 DOI: 10.1007/s11064-009-9972-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Accepted: 04/07/2009] [Indexed: 02/06/2023]
Abstract
Previous studies demonstrated the efficacy of electro-acupuncture (EA) in relieving chronic visceral hypersensitivity (CVH) in IBS rats. However, ST25 which is a key acupoint for patients with IBS has not been reported in these experiments. Eight CVH rats were treated by EA at both ST25 and ST37 for 20 min, once daily for seven consecutive days, model rats (n = 8) and normal rats (n = 8) as controls. After the first EA treatment, the abdominal withdrawal reflex scores were investigated to evaluate the pain threshold. After seven EA treatments, the concentrations of 5-hydroxytryptamine (5-HT), 5-HT3 receptor (5-HT3R) and 5-HT4 receptor (5-HT4R) in colon tissue were assayed quantitatively by enzyme-linked immunosorbent assay. The results showed that EA improved the pain threshold of CVH rats, reduced the 5-HT concentration and increased the 5-HT4R concentration, but had no effect on the 5-HT3R concentration. Further studies are needed to optimize the choice of two-matching points for EA in the treatment of CVH rats.
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Affiliation(s)
- Hui-Rong Liu
- First Affiliated Hospital of Shantou University Medical College, Guangdong Province, People's Republic of China.
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Abstract
The mechanism of visceral pain is still less understood compared with that of somatic pain. This is primarily due to the diverse nature of visceral pain compounded by multiple factors such as sexual dimorphism, psychological stress, genetic trait, and the nature of predisposed disease. Due to multiple contributing factors there is an enormous challenge to develop animal models that ideally mimic the exact disease condition. In spite of that, it is well recognized that visceral hypersensitivity can occur due to (1) sensitization of primary sensory afferents innervating the viscera, (2) hyperexcitability of spinal ascending neurons (central sensitization) receiving synaptic input from the viscera, and (3) dysregulation of descending pathways that modulate spinal nociceptive transmission. Depending on the type of stimulus condition, different neural pathways are involved in chronic pain. In early-life psychological stress such as maternal separation, chronic pain occurs later in life due to dysregulation of the hypothalamic-pituitary-adrenal axis and significant increase in corticotrophin releasing factor (CRF) secretion. In contrast, in early-life inflammatory conditions such as colitis and cystitis, there is dysregulation of the descending opioidergic system that results excessive pain perception (i.e., visceral hyperalgesia). Functional bowel disorders and chronic pelvic pain represent unexplained pain that is not associated with identifiable organic diseases. Often pain overlaps between two organs and approximately 35% of patients with chronic pelvic pain showed significant improvement when treated for functional bowel disorders. Animal studies have documented that two main components such as (1) dichotomy of primary afferent fibers innervating two pelvic organs and (2) common convergence of two afferent fibers onto a spinal dorsal horn are contributing factors for organ-to-organ pain overlap. With reports emerging about the varieties of peptide molecules involved in the pathological conditions of visceral pain, it is expected that better therapy will be achieved relatively soon to manage chronic visceral pain.
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Beyak MJ. Visceral afferents - determinants and modulation of excitability. Auton Neurosci 2009; 153:69-78. [PMID: 19674942 DOI: 10.1016/j.autneu.2009.07.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Revised: 07/13/2009] [Accepted: 07/20/2009] [Indexed: 02/06/2023]
Abstract
An essential property of visceral sensory afferents is to be able to alter their firing properties in response to changes in the microenvironment at the level of the sensory ending. Significant progress has been made in recent years in understanding the ionic mechanisms of the regulation of afferent neuronal excitability, and in identifying the mechanisms by which this can be altered. This article will review some of the recent developments in the state of knowledge regarding mechanisms of increased excitability after inflammation, and pharmacological modulation of excitability, concentrating on afferent nerves innervating the GI tract and urinary bladder.
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Affiliation(s)
- Michael J Beyak
- Department of Medicine, Queen's University, GIDRU Wing, Kingston General Hospital, 76 Stuart St, Kingston, ON, Canada K7L 2V7.
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Song X, Chen BN, Zagorodnyuk VP, Lynn PA, Blackshaw LA, Grundy D, Brunsden AM, Costa M, Brookes SJH. Identification of medium/high-threshold extrinsic mechanosensitive afferent nerves to the gastrointestinal tract. Gastroenterology 2009; 137:274-84, 284.e1. [PMID: 19268671 PMCID: PMC2704260 DOI: 10.1053/j.gastro.2009.02.061] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Revised: 02/18/2009] [Accepted: 02/25/2009] [Indexed: 01/05/2023]
Abstract
BACKGROUND & AIMS Large distentions reliably evoke sensation from the noninflamed, nonischemic bowel, but the specialized afferent axonal structures responsible have not been morphologically identified. We investigated whether their transduction sites are located on major blood vessels close to and within the gut wall. METHODS In vitro extracellular recordings were made from mesenteric nerve trunks in guinea pig ileum, combined with rapid axonal dye filling and immunohistochemical analysis of nerve trunks. RESULTS Recordings revealed sensory fibers with focal mechanosensitive sites in the mesenteries that could be activated by von Frey hairs and by stretch. Dye filling revealed varicose branching sensory axons on mesenteric blood vessels but no other anatomically specialized structures in mesenteric membranes or the serosa. Large-amplitude stretch and von Frey hairs also activated sensory endings within the gut wall itself but only if the submucosa was present; mechanotransduction sites in the serosa or outer muscle layers were sparse. Mechanosensitive sites in submucosa were exclusively associated with submucosal blood vessels. Submucosal endings had significantly higher thresholds to stretch than specialized low-threshold mechanoreceptors characterized previously in the rectum (P < .05) and were therefore classified as medium/high-threshold mechanoreceptors. Capsaicin (0.3-1 micromol/L) activated most mechanosensitive mesenteric (68%) and submucosal (85%) afferent endings. Similar intramural mechanosensitive afferent endings on blood vessels also exist in the colon and bladder. CONCLUSIONS Varicose branching axons of sensory neurons on intramural blood vessels, previously shown to mediate sensory vasodilation, are transduction sites for medium/high-threshold, stretch-sensitive mechanoreceptors, encoding large distentions in hollow viscera.
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Affiliation(s)
- Xingyun Song
- Dept of Human Physiology, Flinders University, Bedford Park, South Australia 5042, Tel: +61 8 8204 4201, Fax: +61 8 8204 5768
| | - Bao Nan Chen
- Dept of Human Physiology, Flinders University, Bedford Park, South Australia 5042, Tel: +61 8 8204 4201, Fax: +61 8 8204 5768
| | - Vladimir P Zagorodnyuk
- Dept of Human Physiology, Flinders University, Bedford Park, South Australia 5042, Tel: +61 8 8204 4201, Fax: +61 8 8204 5768
| | - Penny A Lynn
- Dept of Human Physiology, Flinders University, Bedford Park, South Australia 5042, Tel: +61 8 8204 4201, Fax: +61 8 8204 5768
| | - L Ashley Blackshaw
- Nerve–Gut Research Laboratory, Department of Gastroenterology, Hepatology and General Medicine, Royal Adelaide Hospital, Adelaide, South Australia, 5000, Australia
| | - David Grundy
- Dept of Biomedical Science, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield S10-2TN, UK
| | - Alan M Brunsden
- Dept of Biomedical Science, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield S10-2TN, UK
| | - Marcello Costa
- Dept of Human Physiology, Flinders University, Bedford Park, South Australia 5042, Tel: +61 8 8204 4201, Fax: +61 8 8204 5768
| | - Simon JH Brookes
- Dept of Human Physiology, Flinders University, Bedford Park, South Australia 5042, Tel: +61 8 8204 4201, Fax: +61 8 8204 5768
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Linden DR, White SL, Brooks EM, Mawe GM. Novel promoter and alternate transcription start site of the human serotonin reuptake transporter in intestinal mucosa. Neurogastroenterol Motil 2009; 21:534-41, e10-1. [PMID: 19222758 PMCID: PMC2722877 DOI: 10.1111/j.1365-2982.2008.01247.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Selective serotonin-reuptake inhibitors are therapies for psychological and bowel disorders, but produce adverse effects in the non-targeted system. To determine whether human serotonin-selective reuptake transporter (SERT) transcripts in the intestine are different from the brain, rapid amplification of cDNA ends, primer extension and RT-PCR assays were used to evaluate SERT transcripts from each region. Potential SLC6A4 gene promoter constructs were evaluated with a secreted alkaline phosphatase reporter assay. A novel transcript of the human SLC6A4 gene was discovered that predominates in the intestine, and differs from previous transcripts in the 5'-untranslated region. The distinct transcriptional start site and alternate promoter suggest that gastrointestinal SERT can be differentially regulated from brain SERT, may explain why the polymorphism in the previously identified promoter is associated with affective disorders, but not associated with gastrointestinal dysfunction, and suggest the intriguing possibility of the development of site-specific therapeutics for SERT regulation in the treatment of multiple disorders.
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Affiliation(s)
- D R Linden
- Department of Anatomy and Neurobiology, The University of Vermont College of Medicine, Burlington, VT 05405, USA
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Schloithe AC, Sutherland K, Woods CM, Blackshaw LA, Davison JS, Toouli J, Saccone GTP. A novel preparation to study rat pancreatic spinal and vagal mechanosensitive afferents in vitro. Neurogastroenterol Motil 2008; 20:1060-9. [PMID: 18482253 DOI: 10.1111/j.1365-2982.2008.01141.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The management of pancreatic pain is a significant clinical problem so understanding of how sensory signals are generated in pancreatic tissue is fundamental. We aimed to characterize mechanosensitive and chemosensitive properties of pancreatic spinal and vagal afferents in vitro. Spinal and vagal afferent preparations from Sprague-Dawley rats were established incorporating the left splanchnic nerve or vagus nerves respectively. The common bile duct was cannulated for distension of the pancreatic duct with fluid. Nerve discharge evoked by blunt probing, duct distension or electrical stimulation was obtained from teased nerve bundles using standard extra-cellular recording. Discharge from 197 spinal afferent bundles was recorded, of which 57% displayed spontaneous activity. Blunt probing revealed 61 mechanosensitive receptive fields which were associated primarily with arteries/blood vessels (33/61) and the parenchyma (22/61). All mechanosensitive responses were slowly adapting, with 33% continuing to discharge after termination of the stimulus and 60% displaying a response threshold <10 g. Application of chemical mediators (bradykinin, histamine, 5-hydroxytryptamine, cholecystokinin octapeptide) evoked a response from 31/57 units, with 33% excitatory and 23% inhibitory. Spontaneous discharge was recorded from 72% of 135 vagal bundles. Mechanosensitive receptive fields were not identified in the pancreas but were evident in adjacent organs. No spinal or vagal afferent response to duct distension was obtained. In conclusion, pancreatic mechanosensitive spinal afferents are common, in contrast to pancreatic mechanosensitive vagal afferents indicating that pancreatic sensory innervation is predominantly spinal. Chemosensitive spinal afferent nerve endings are present in the pancreas and respond to a variety of inflammatory and physiological mediators.
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Affiliation(s)
- A C Schloithe
- Department of General and Digestive Surgery, Flinders University, Flinders Medical Centre, Adelaide, SA, Australia
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Taniguchi H, Ariga H, Zheng J, Ludwig K, Mantyh C, Pappas TN, Takahashi T. Endogenous ghrelin and 5-HT regulate interdigestive gastrointestinal contractions in conscious rats. Am J Physiol Gastrointest Liver Physiol 2008; 295:G403-11. [PMID: 18566321 DOI: 10.1152/ajpgi.90260.2008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Endogenous ghrelin causes interdigestive contractions of the stomach in rats. In contrast, previous studies showed that 5-HT(3) and 5-HT(4) receptors were involved in regulating intestinal interdigestive contractions. We studied the possible role of endogenous ghrelin and 5-HT regulating interdigestive gastrointestinal (GI) contractions in rats. Four strain gauge transducers were implanted on the antrum, duodenum, and proximal and distal jejunum. After an overnight fast, GI contractions were recorded in freely moving conscious rats and ghrelin receptor antagonists [(d-lys3)GHRP6; 1 micromol/kg], 5-HT(3) antagonists (Ondansetron; 0.5 mg/kg) and 5-HT(4) antagonists (GR 125,487; 1 mg/kg) were administered (bolus iv). To evaluate the relationship between the luminal concentrations of 5-HT and phase III-like contractions of the duodenum, duodenal juice was collected via the intraduodenal catheter. 5-HT content of the duodenal juice was measured by HPLC. (d-lys3)GHRP6 significantly attenuated the occurrence and amplitude of phase III-like contractions of the antrum, but not the duodenum and jejunum. 5-HT(4) antagonists significantly reduced spontaneous phase III-like contractions of the jejunum, without affecting those of the antrum and duodenum. In contrast, 5-HT(3) antagonists did not affect phase III-like contractions in GI tract. Luminal concentration of 5-HT at the phase III-like contraction (36.0 +/- 13.3 ng/ml, n = 9) was significantly higher than that at the phase I-like contractions of the duodenum (4.9 +/- 1.6 ng/ml, n = 9, P < 0.05). It is suggested that released ghrelin from the gastric mucosa mediates gastric phase III-like contractions, whereas 5-HT released from enterochromaffin cells of the duodenal mucosa mediates intestinal phase III-like contractions via 5-HT(4) receptors.
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Affiliation(s)
- Hiroshi Taniguchi
- Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA
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Keating C, Beyak M, Foley S, Singh G, Marsden C, Spiller R, Grundy D. Afferent hypersensitivity in a mouse model of post-inflammatory gut dysfunction: role of altered serotonin metabolism. J Physiol 2008; 586:4517-30. [PMID: 18653657 DOI: 10.1113/jphysiol.2008.156984] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Visceral hypersensitivity is an important clinical feature associated with irritable bowel syndrome which in some patients has been linked to prior infection. Here we employ an animal model in which transient infection leads to persistent gut dysfunction to investigate the role of altered 5-HT metabolism upon afferent mechanosensensitivity in the post-infected gut. Jejunal segments isolated from Trichinella spiralis-infected mice were used to assess 5-HT metabolism whilst afferent activity in T. spiralis-infected mice was studied by extracellular recordings from jejunal mesenteric afferent bundles and patch clamp recordings of isolated nodose ganglion neurons (NGNs). During acute infection, intestinal 5-HT content and release increased, 5-HT turnover decreased and afferent discharge in response to mechanical stimulation was attenuated. By day 28 post infection (PI), 5-HT turnover had normalized, but 5-HT content and release were still elevated. This was associated with afferent mechano-hypersensitivity, which persisted for 8 weeks PI and was susceptible to 5-HT(3) receptor blockade. NGNs from post-infected animals were more excitable than controls but their current densities in response to 2-methyl-5-HT were lower. T. spiralis infection increased mucosal 5-HT bioavailability and affected the spontaneous activity and mechanosensitivity of gastrointestinal sensory nerves. This involved an initial hyposensitivity occurring during acute infection followed by long-term hypersensitivity in the post-infectious period that was in part mediated by 5-HT acting via 5-HT(3) receptors. Functional down-regulation of 5-HT(3) receptors also occurs in the post-infected animals, which may represent an adaptive response to increased mucosal 5-HT bioavailability.
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Affiliation(s)
- Christopher Keating
- Department of Biomedical Sciences, Florey Building, University of Sheffield, Sheffield, S10 2TN, UK
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Yang N, Tian YM, Zhang XH, Zheng LF, Xue H, Chen X, Zhu L, Zhu JX. A dual role of 5-hydroxytryptamine receptor 3 in serotonin induced ion transport in rat distal colon. Eur J Pharmacol 2008; 584:137-43. [PMID: 18313044 DOI: 10.1016/j.ejphar.2008.01.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Revised: 12/23/2007] [Accepted: 01/21/2008] [Indexed: 11/29/2022]
Abstract
5-hydroxytryptamine (5-HT)-evoked intestinal secretion can be divided into neural and non-neural pathway. Recently, 5-HT(3) receptor in neural pathway received much attention as a possible target in bowel diseases. The present study aims to investigate the effects of 5-HT(3) receptor in different enteric neural plexus (myenteric plexus and submucosal plexus) on rat colonic ion transport by using rat intact colon and mucosa/submucosa preparations. Ussing chamber and real-time PCR techniques were performed in our present study. Surprisingly, we found that in mucosa/submucosa preparations, 5-HT-induced DeltaI(SC) (change in short-circuit current) was not inhibited, but further increased by pretreatment with 5-HT(3) receptor antagonists, MDL72222 and Tropanyl-3, 5-dimethylbenzoate. And this response was significantly attenuated in the presence of tetrodotoxin (TTX). Conversely, in rat intact colon, 5-HT(3) receptor antagonists significantly inhibited 5-HT-induced DeltaI(SC). The results from real-time PCR proved the existence of 5-HT(3) receptor in muscularis externa and submucosa. Taken together, 5-HT(3) receptors possess a role of dual regulation on electrolyte secretion in rat distal colon, the neural stimulatory effect of 5-HT(3) receptor in myenteric plexus and the inhibitory effect of 5-HT(3) receptor in submucosal plexus.
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Affiliation(s)
- Ning Yang
- Department of Physiology, School of Basic Medical Sciences, Capital Medical University, Beijing (100069), People's Republic of China
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