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Uyttebroek L, Pype C, Hubens G, Timmermans JP, Van Nassauw L. Effect of TNBS-induced colitis on enteric neuronal subpopulations in adult zebrafish. Eur J Histochem 2020; 64. [PMID: 32875777 PMCID: PMC7459238 DOI: 10.4081/ejh.2020.3161] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 08/24/2020] [Indexed: 02/08/2023] Open
Abstract
Inflammatory bowel disease (IBD) includes inflammation of the gastrointestinal (GI) tract and is characterized by periods of acute inflammation and remission. Therapeutic management of IBD is still problematic, because of incomplete understanding its pathogenesis. This study focuses on the effect of 2,4,6-trinitrobenzene sulphonic acid (TNBS)-induced colitis on changes in enteric neuronal subpopulations in adult zebrafish. These changes are suggested to be related to the altered neuro-immune interactions and GI motility, and in IBD pathogenesis. New insights into neuroplasticity will be instrumental in finding appropriate therapeutic treatments. TNBS was intraluminally administered in the distal intestine (DI) of anesthetized adult zebrafish. A histological time course of the intestinal inflammatory response was created to establish optimal TNBS concentration and acute inflammation phase. Using double immunolabelling on whole mounts, the effect of inflammation on neuronal populations was analyzed. Based on intestinal wall thickening, epithelial fold disruption, reduced goblet cell number, and eosinophil infiltration, our analysis indicated that the optimal TNBS concentration (320 mM in 25% ethanol) inducing non-lethal inflammation reached a peak at 6 h post-induction. The inflammatory response returned to baseline values at 3 days post-induction. At the acute inflammation phase, no influence on the distribution or proportion of nitrergic neurons was observed, while only the proportion of cholinergic neurons was significantly reduced in the DI. The proportion of serotonergic neurons was significantly increased in the entire intestine during inflammation. This study describes a method of TNBS-induced colitis in the adult zebrafish. Given that the acute inflammation phase is accompanied by neuroplasticity comparable to changes observed in IBD patients, and the unique and versatile characteristics of the zebrafish, allows this model to be used alongside IBD animal models to unravel IBD pathology and to test new IBD therapies.
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Affiliation(s)
- Leen Uyttebroek
- Laboratory of Human Anatomy, Faculty of Medicine and Health Sciences, University of Antwerp.
| | - Casper Pype
- Laboratory of Applied Veterinary Morphology, Department of Veterinary Sciences, University of Antwerp.
| | - Guy Hubens
- Laboratory of Human Anatomy, Faculty of Medicine and Health Sciences, University of Antwerp.
| | - Jean-Pierre Timmermans
- Laboratory of Cell Biology and Histology, Department of Veterinary Sciences, University of Antwerp.
| | - Luc Van Nassauw
- Laboratory of Human Anatomy, Faculty of Medicine and Health Sciences, University of Antwerp.
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Escalante J, McQuade RM, Stojanovska V, Nurgali K. Impact of chemotherapy on gastrointestinal functions and the enteric nervous system. Maturitas 2017; 105:23-29. [DOI: 10.1016/j.maturitas.2017.04.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 04/25/2017] [Indexed: 02/07/2023]
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McQuade RM, Stojanovska V, Donald E, Abalo R, Bornstein JC, Nurgali K. Gastrointestinal dysfunction and enteric neurotoxicity following treatment with anticancer chemotherapeutic agent 5-fluorouracil. Neurogastroenterol Motil 2016; 28:1861-1875. [PMID: 27353132 DOI: 10.1111/nmo.12890] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 05/29/2016] [Indexed: 12/23/2022]
Abstract
BACKGROUND The use of the anticancer chemotherapeutic agent 5-fluorouracil (5-FU) is often limited by nausea, vomiting, constipation, and diarrhea; these side-effects persist long after treatment. The effects of 5-FU on enteric neurons have not been studied and may provide insight into the mechanisms underlying 5-FU-induced gastrointestinal dysfunction. METHODS Balb/c mice received intraperitoneal injections of 5-FU (23 mg/kg) 3 times/week for 14 days. Gastrointestinal transit was analysed in vivo prior to and following 3, 7, and 14 days of 5-FU treatment via serial x-ray imaging. Following 14 days of 5-FU administration, colons were collected for assessment of ex vivo colonic motility, gross morphological structure, and immunohistochemical analysis of myenteric neurons. Fecal lipocalin-2 and CD45+ leukocytes in the colon were analysed as markers of intestinal inflammation. KEY RESULTS Short-term administration of 5-FU (3 days) increased gastrointestinal transit, induced acute intestinal inflammation and reduced the proportion of neuronal nitric oxide synthase-immunoreactive neurons. Long-term treatment (7, 14 days) resulted in delayed gastrointestinal transit, inhibition of colonic migrating motor complexes, increased short and fragmented contractions, myenteric neuronal loss and a reduction in the number of ChAT-immunoreactive neurons after the inflammation was resolved. Gross morphological damage to the colon was observed following both short- and long-term 5-FU treatment. CONCLUSIONS & INFERENCES Our results indicate that 5-FU induces accelerated gastrointestinal transit associated with acute intestinal inflammation at day 3 after the start of treatment, which may have led to persistent changes in the ENS observed after days 7 and 14 of treatment contributing to delayed gastrointestinal transit and colonic dysmotility.
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Affiliation(s)
- R M McQuade
- Centre for Chronic Disease, College of Health and Biomedicine, Victoria University, Melbourne, VIC, Australia.,Western Centre for Health, Research and Education, Sunshine Hospital, St Albans, VIC, Australia
| | - V Stojanovska
- Centre for Chronic Disease, College of Health and Biomedicine, Victoria University, Melbourne, VIC, Australia.,Western Centre for Health, Research and Education, Sunshine Hospital, St Albans, VIC, Australia
| | - E Donald
- Centre for Chronic Disease, College of Health and Biomedicine, Victoria University, Melbourne, VIC, Australia.,Western Centre for Health, Research and Education, Sunshine Hospital, St Albans, VIC, Australia
| | - R Abalo
- Área de Farmacología y Nutrición y Unidad Asociada al Instituto de Química Médica (IQM) y al Instituto de Investigación en Ciencias de la Alimentación (CIAL) del Consejo Superior de Investigaciones Científicas (CSIC), Grupo de Excelencia Investigadora URJC-Banco de Santander-Grupo Multidisciplinar de Investigación y Tratamiento del Dolor (i+DOL), Universidad Rey Juan Carlos, Alcorcón, Madrid, Spain
| | - J C Bornstein
- Department of Physiology, Melbourne University, Melbourne, VIC, Australia
| | - K Nurgali
- Centre for Chronic Disease, College of Health and Biomedicine, Victoria University, Melbourne, VIC, Australia.,Western Centre for Health, Research and Education, Sunshine Hospital, St Albans, VIC, Australia
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Vanormelingen C, Vanuytsel T, Masaoka T, De Hertogh G, Vanheel H, Vanden Berghe P, Farré R, Tack J. The normoglycaemic biobreeding rat: a spontaneous model for impaired gastric accommodation. Gut 2016; 65:73-81. [PMID: 25410165 DOI: 10.1136/gutjnl-2014-308154] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 10/22/2014] [Indexed: 01/28/2023]
Abstract
OBJECTIVE Impaired gastric accommodation is reported in patients with functional dyspepsia (FD). Previous findings in postinfectious patients with FD suggest that low-grade inflammation and dysfunction of nitrergic nerves play a role in impaired accommodation. To date, spontaneous animal models to study the relationship between these changes are lacking. We hypothesise that the normoglycaemic BioBreeding diabetes-prone (BB-DP) rat provides an animal model of inflammation-induced impaired gastric motor function. DESIGN Control diabetes-resistant biobreeding, normoglycaemic and hyperglycaemic BB-DP rats were sacrificed at the age of 30, 70 and 220 days and gastric fundus tissue was harvested to study nitrergic motor control, inflammation and expression of neuronal isoform of nitric oxide synthase (nNOS) and inducible isoform of nitric oxide synthase (iNOS). Nutrient-induced changes in intragastric pressure (IGP) were measured in normoglycaemic BB-DP rats to study accommodation. RESULTS No differences in nitrergic function and inflammation were observed between BB-DP and control rats at 30 days. The nitrergic component of the fundic muscle relaxation was reduced in BB-DP rats of 70 and 220 days. This was accompanied by a significant loss of nNOS proteins. IGP significantly increased during nutrient infusion in BB-DP rats of 220 days, indicating impaired accommodation. Infiltration of polymorphonuclear cells, increased myeloperoxidase activity and increased expression of iNOS was observed in the fundic mucosa and muscularis propria of 70-day-old and 220-day-old BB-DP rats. CONCLUSIONS BB-DP rats of 220 days display altered fundic motor control and impaired accommodation, which is least partially explained by loss of nitrergic function. This may be related to inflammatory changes in the neuromuscular layer, suggesting that normoglycaemic BB-DP rats provide a spontaneous model for inflammation-induced impaired gastric accommodation.
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Affiliation(s)
- Christophe Vanormelingen
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Tim Vanuytsel
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Tatsuhiro Masaoka
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Gert De Hertogh
- Department of Pathology, University of Leuven, Leuven, Belgium
| | - Hanne Vanheel
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Pieter Vanden Berghe
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Ricard Farré
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Jan Tack
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
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Vanuytsel T, Vanormelingen C, Vanheel H, Masaoka T, Salim Rasoel S, Tóth J, Houben E, Verbeke K, De Hertogh G, Berghe PV, Tack J, Farré R. From intestinal permeability to dysmotility: the biobreeding rat as a model for functional gastrointestinal disorders. PLoS One 2014; 9:e111132. [PMID: 25354336 PMCID: PMC4212994 DOI: 10.1371/journal.pone.0111132] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 09/19/2014] [Indexed: 12/15/2022] Open
Abstract
Background Impaired intestinal barrier function, low-grade inflammation and altered neuronal control are reported in functional gastrointestinal disorders. However, the sequence of and causal relation between these events is unclear, necessitating a spontaneous animal model. The aim of this study was to describe the natural history of intestinal permeability, mucosal and neuromuscular inflammation and nitrergic motor neuron function during the lifetime of the BioBreeding (BB) rat. Methods Normoglycemic BB-diabetes prone (DP) and control rats were sacrificed at different ages and jejunum was harvested to characterize intestinal permeability, inflammation and neuromuscular function. Results Both structural and functional evidence of increased intestinal permeability was found in young BB-DP rats from the age of 50 days. In older animals, starting in the mucosa from 70 days and in half of the animals also in the muscularis propria from 110 days, an inflammatory reaction, characterized by an influx of polymorphonuclear cells and higher myeloperoxidase activity, was observed. Finally, in animals older than 110 days, coinciding with a myenteric ganglionitis, a loss of nitrergic neurons and motor function was demonstrated. Conclusion In the BB-rat, mucosal inflammatory cell infiltration is preceded by intestinal barrier dysfunction and followed by myenteric ganglionitis and loss of nitrergic function. This sequence supports a primary role for impaired barrier function and provides an insightful model for the pathogenesis of functional gastrointestinal disorders.
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Affiliation(s)
- Tim Vanuytsel
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Christophe Vanormelingen
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Hanne Vanheel
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Tatsuhiro Masaoka
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Shadea Salim Rasoel
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Joran Tóth
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Els Houben
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Kristin Verbeke
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Gert De Hertogh
- Department of Pathology, University Hospital, University of Leuven, Leuven, Belgium
| | - Pieter Vanden Berghe
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Jan Tack
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
- * E-mail:
| | - Ricard Farré
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos II, Barcelona, Spain
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Abstract
The gastrointestinal tract is innervated by several distinct populations of neurons, whose cell bodies either reside within (intrinsic) or outside (extrinsic) the gastrointestinal wall. Normally, most individuals are unaware of the continuous, complicated functions of these neurons. However, for patients with gastrointestinal disorders, such as IBD and IBS, altered gastrointestinal motility, discomfort and pain are common, debilitating symptoms. Although bouts of intestinal inflammation underlie the symptoms associated with IBD, increasing preclinical and clinical evidence indicates that infection and inflammation are also key risk factors for the development of other gastrointestinal disorders. Notably, a strong correlation exists between prior exposure to gut infection and symptom occurrence in IBS. This Review discusses the evidence for neuroplasticity (structural, synaptic or intrinsic changes that alter neuronal function) affecting gastrointestinal function. Such changes are evident during inflammation and, in many cases, long after healing of the damaged tissues, when the nervous system fails to reset back to normal. Neuroplasticity within distinct populations of neurons has a fundamental role in the aberrant motility, secretion and sensation associated with common clinical gastrointestinal disorders. To find appropriate therapeutic treatments for these disorders, the extent and time course of neuroplasticity must be fully appreciated.
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Masaoka T, Vanuytsel T, Vanormelingen C, Kindt S, Salim Rasoel S, Boesmans W, De Hertogh G, Farré R, Berghe PV, Tack J. A spontaneous animal model of intestinal dysmotility evoked by inflammatory nitrergic dysfunction. PLoS One 2014; 9:e95879. [PMID: 24819503 PMCID: PMC4018386 DOI: 10.1371/journal.pone.0095879] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Accepted: 04/01/2014] [Indexed: 01/08/2023] Open
Abstract
Background and Aims Recent reports indicate the presence of low grade inflammation in functional gastrointestinal disorders (FGID), in these cases often called “post-inflammatory” FGIDs. However, suitable animal models to study these disorders are not available. The Biobreeding (BB) rat consists of a diabetes-resistant (BBDR) and a diabetes-prone (BBDP) strain. In the diabetes-prone strain, 40–60% of the animals develop diabetes and concomitant nitrergic dysfunction. Our aim was to investigate the occurrence of intestinal inflammation, nitrergic dysfunction and intestinal dysmotility in non-diabetic animals. Methods Jejunal inflammation (MPO assay, Hematoxylin&Eosin staining and inducible nitric oxide synthase (iNOS) mRNA expression), in vitro jejunal motility (video analysis) and myenteric neuronal numbers (immunohistochemistry) were assessed in control, normoglycaemic BBDP and diabetic BBDP rats. To study the impact of iNOS inhibition on these parameters, normoglycaemic BBDP rats were treated with aminoguanidine. Results Compared to control, significant polymorphonuclear (PMN) cell infiltration, enhanced MPO activity, increased iNOS mRNA expression and a decreased ratio of nNOS to Hu-C/D positive neurons were observed in both normoglycaemic and diabetic BBDP rats. Aminoguanidine treatment decreased PMN infiltration, iNOS mRNA expression and MPO activity. Moreover, it restored the ratio of nNOS to Hu-C/D positive nerves in the myenteric plexus and decreased the abnormal jejunal elongation and dilation observed in normoglycaemic BBDP rats. Conclusions Aminoguanidine treatment counteracts the inflammation-induced nitrergic dysfunction and prevents dysmotility, both of which are independent of hyperglycaemia in BB rats. Nitrergic dysfunction may contribute to the pathophysiology of “low-grade inflammatory” FGIDs. Normoglycaemic BBDP rats may be considered a suitable animal model to study the pathogenesis of FGIDs.
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Affiliation(s)
- Tatsuhiro Masaoka
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Tim Vanuytsel
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Christophe Vanormelingen
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Sebastien Kindt
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Shadea Salim Rasoel
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Werend Boesmans
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Gert De Hertogh
- Department of Pathology, University of Leuven, Leuven, Belgium
| | - Ricard Farré
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Pieter Vanden Berghe
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Jan Tack
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
- * E-mail:
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Abdu FB. Neuronal activation and plasticity in Schistosoma mansoni infected mice. Saudi J Biol Sci 2013; 19:495-501. [PMID: 23961211 DOI: 10.1016/j.sjbs.2012.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Revised: 07/09/2012] [Accepted: 07/14/2012] [Indexed: 10/28/2022] Open
Abstract
Schistosomiasis leads to structural and functional changes which may result from unbalanced release of some inflammatory mediators. The aim of the study was to investigate the effect of intestinal parasitic infection on nitric oxide release and to evaluate the neural plasticity that leads to motility disturbance. Experiments were performed in Swiss mice 8- and 12-weeks following infection with Schistosoma mansoni compared to untreated controls. Jejunal motility was assessed using a Trendelenburg preparation to study aboral directed peristaltic pressure waves. Histological examination was used to determine the pathological characteristics of inflammation. Parasitic infection produces diffuse inflammatory infiltrate in both 8- and 12-weeks infected animals. Inflammation had significant effect on peristaltic pressure waves amplitude and intervals at 8-weeks compared to control; whereas, in 12-weeks post infection there was a significant decrease in peristaltic pressure waves amplitude and interval compared to 8- weeks and control. Nitric oxide synthase inhibitor (L-NAME 100 μM) induced a significant increase in amplitude and decrease in intervals in control, 8- and 12- weeks infected animals. In conclusion, parasitic infection leads to disturbance in the release of the inflammatory mediators. This study indicated the role of nitric oxide in developing granulomatous inflammation and participating in motility disturbance.
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Affiliation(s)
- Faiza B Abdu
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, P.O. Box 42699, Jeddah 21551, Saudi Arabia
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Park KS. Impact of myenteric plexus alterations on diabetes related gastrointestinal dysmotility. J Neurogastroenterol Motil 2013; 19:121-3. [PMID: 23667742 PMCID: PMC3644647 DOI: 10.5056/jnm.2013.19.2.121] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Revised: 02/06/2013] [Accepted: 02/06/2013] [Indexed: 01/27/2023] Open
Affiliation(s)
- Kyung Sik Park
- Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Korea
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Demedts I, Masaoka T, Kindt S, De Hertogh G, Geboes K, Farré R, Vanden Berghe P, Tack J. Gastrointestinal motility changes and myenteric plexus alterations in spontaneously diabetic biobreeding rats. J Neurogastroenterol Motil 2013; 19:161-70. [PMID: 23667747 PMCID: PMC3644652 DOI: 10.5056/jnm.2013.19.2.161] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 12/17/2012] [Accepted: 01/02/2013] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND/AIMS Type 1 diabetes is often accompanied by gastrointestinal motility disturbances. Vagal neuropathy, hyperglycemia, and alterations in the myenteric plexus have been proposed as underlying mechanism. We therefore studied the relationship between vagal function, gastrointestinal motiliy and characteristics of the enteric nervous system in the biobreeding (BB) rat known as model for spontaneous type 1 diabetes. METHODS Gastric emptying breath test, small intestinal electromyography, relative risk-interval variability, histology and immunohistochemistry on antral and jejunal segments were performed at 1, 8 and 16 weeks after diabetes onset and on age-matched controls. RESULTS We observed no consistent changes in relative risk-interval variability and gastric emptying rate. There was however, a loss of phases 3 with longer duration of diabetes on small intestinal electromyography. We found a progressive decrease of nitrergic neurons in the myenteric plexus of antrum and jejunum, while numbers of cholinergic nerve were not altered. In addition, a transient inflammatory infiltrate in jejunal wall was found in spontaneous diabetic BB rats at 8 weeks of diabetes. CONCLUSIONS In diabetic BB rats, altered small intestinal motor control associated with a loss of myenteric nitric oxide synthase expression occurs, which does not depend on hyperglycemia or vagal dysfunction, and which is preceded by transient intestinal inflammation.
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Affiliation(s)
- Ingrid Demedts
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Tatsuhiro Masaoka
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Sebastien Kindt
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Gert De Hertogh
- Department of Pathology, University of Leuven, Leuven, Belgium
| | - Karel Geboes
- Department of Pathology, University of Leuven, Leuven, Belgium
| | - Ricard Farré
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Pieter Vanden Berghe
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Jan Tack
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
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Zhou H, Gao J, Zou D, Wu W, Li Z. Effect of octreotide on enteric motor neurons in experimental acute necrotizing pancreatitis. PLoS One 2012; 7:e52163. [PMID: 23300603 PMCID: PMC3530548 DOI: 10.1371/journal.pone.0052163] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 11/12/2012] [Indexed: 02/07/2023] Open
Abstract
Background/Aims Amelioration of intestinal dysmotility and stasis during the early period of acute necrotizing pancreatitis (ANP) appears to be important to reduce the risks of secondary pancreatic infection. We aimed to characterize the association between the neuropathy of the enteric nervous system and gut dysfunction and to examine the effect of octreotide on motor innervation in the early stage of ANP. Methodology/Principal Findings The rats were randomly divided into eight groups: control+saline; control+octreotide; ANP+saline and ANP+octreotide (24 h, 48 h, 72 h). The spontaneous activity of ileal segments and the response to ACh, l-NNA were recorded. The alterations of myenteric neuronal nitric oxide synthase (nNOS), choline acetyltransferase (CHAT), PGP9.5 and somatostatin receptor 2 (SSTR2) immunoreactive cells were evaluated by immunofluorescence and the protein expression of nNOS and CHAT were evaluated by western blot. We found the amplitude of spontaneous contractions at 48 h and the response to ACh at 24 h declined in the ANP+saline rats. A higher contractile response to both ACh and to l-NNA was observed in the ANP+octreotide group, compared with the ANP+saline rats at 24 h. A significant reduction in the nNOS and cholinergic neurons was observed in ANP+saline rats at the three time points. However, this reduction was greatly ameliorated in the presence of octreotide at 24 h and 48 h. The protein expression of CHAT neurons at 24 h and the nNOS neurons at 48 h in the ANP+octreotide rats was much higher than the ANP+saline rats. Conclusion The pathogenesis of ileus in the early stage of ANP may be related to the neuropathy of the enteric nervous system. Octreotide may reduce the severity of ileus by lessening the damage to enteric motor innervation.
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Affiliation(s)
- Hui Zhou
- Department of Gastroenterology, Shanghai First People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
- Division of Gastroenterology, Department of Internal Medicine, Changhai Hospital, Second Military Medical University, Shanghai, China
| | - Jun Gao
- Division of Gastroenterology, Department of Internal Medicine, Changhai Hospital, Second Military Medical University, Shanghai, China
| | - Duowu Zou
- Division of Gastroenterology, Department of Internal Medicine, Changhai Hospital, Second Military Medical University, Shanghai, China
| | - Wenbin Wu
- Laboratory of Stress Research, Department of Internal Medicine, Changhai Hospital, Second Military Medical University, Shanghai, China
| | - Zhaoshen Li
- Division of Gastroenterology, Department of Internal Medicine, Changhai Hospital, Second Military Medical University, Shanghai, China
- * E-mail:
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12
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Gap junctions in dorsal root ganglia: Possible contribution to visceral pain. Eur J Pain 2012; 14:49.e1-11. [DOI: 10.1016/j.ejpain.2009.02.005] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2008] [Revised: 02/12/2009] [Accepted: 02/16/2009] [Indexed: 01/08/2023]
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Sigalet DL, Wallace L, De Heuval E, Sharkey KA. The effects of glucagon-like peptide 2 on enteric neurons in intestinal inflammation. Neurogastroenterol Motil 2010; 22:1318-e350. [PMID: 20718942 DOI: 10.1111/j.1365-2982.2010.01585.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Intestinal inflammation alters the structure and function of the enteric nervous system (ENS). Glucagon-like peptide 2 (GLP-2) reduces intestinal inflammation and has trophic effects on isolated neurons. This study examined the effects of GLP-2 treatment on the submucosal plexus of rat colon in the trinitrobenzene sulfonic acid (TNBS) model of colitis. METHODS After administration of TNBS or saline/ethanol for controls, animals were allocated to treatment with GLP-2 (50 μg kg⁻¹ day⁻¹, s.c.) or sham injection of vehicle, twice daily. Animals were monitored, following clinical parameters, and killed on day 5. The number of neuronal cell bodies per ganglion was quantified using immunohistochemistry on submucosal whole mount preparations, with further characterization of specific subpopulations using antibodies against vasoactive intestinal polypeptide (VIP), neuronal nitric oxide synthase (nNOS), and enteric glial cells with glial fibrillary acid protein and S100. KEY RESULTS Glucagon-like peptide 2 treatment was associated with a significant amelioration of weight loss, and reduced neutrophil infiltration and microscopic colitis scores in the TNBS animals. Inflammation resulted in a loss of enteric neurons in submucosal ganglia; GLP-2 treatment restored the enteric neuronal populations to normal. In control, non-inflamed animals, GLP-2 treatment increased the number of VIP expressing neurons per ganglion; in TNBS-treated animals, GLP-2 prevented an inflammation-induced reduction in the numbers of VIP expressing neurons per ganglion. Glucagon-like peptide 2 did not change the numbers of nNOS neurons or enteric glial cells in either the control, or inflamed state. CONCLUSIONS & INFERENCES These findings show that GLP-2 increased the number of VIP expressing neurons in normal animals, and prevents the inflammation-induced loss of neurons in the colonic submucosal ganglia, with an increase in the proportion of VIP expressing neurons. They suggest that GLP-2 may have a role in protecting or regulating the circuitry of the ENS under basal and inflamed states.
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Affiliation(s)
- D L Sigalet
- Department of Surgery, Faculty of Medicine, Snyder Institute of Infection, Immunity & Inflammation, Alberta Children's Hospital, University of Calgary, Calgary, AB, Canada.
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Damage of the interstitial cells of Cajal and myenteric neurons causing ileus in acute necrotizing pancreatitis rats. Surgery 2010; 149:262-75. [PMID: 20570303 DOI: 10.1016/j.surg.2010.04.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 04/23/2010] [Indexed: 01/06/2023]
Abstract
BACKGROUND Small intestinal motility is impaired in acute necrotizing pancreatitis (ANP). The present study was designed to detect the impairment in small intestinal motility and to assess the role of interstitial cells of Cajal (ICC), myenteric neurons and the associated mechanism in the pathogenesis of ileus during experimentally induced acute pancreatitis. METHODS ANP was induced by intraperitoneal injections of 30% L-ornithine at a dose of 3 g/kg at hourly intervals. The alterations of small intestine electrical activity--migrating myoelectric complexes (MMCs), and slow waves--were measured 24 hr after ANP induction. The spontaneous mechanical activity and the contractile response to ACh, KCl, tetrodotoxin (TTX) and the nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine (L-NNA) were evaluated by organ bath technique, and the morphologic alterations of the network of ICC, myenteric neurons and neuronal nitric oxide synthase (nNOS) immunoreactive cells were evaluated using the markers of c-Kit, PGP9.5, and nNOS, respectively. To demonstrate the deficiencies in enteric neuronal origin, we also measured nNOS expression in the muscular layer of ileum. RESULTS L-ornithine-induced necrotizing pancreatitis manifests with multiple symptoms, including decreased amplitude of spontaneous contractions in small intestinal smooth muscle, declined contractile response to ACh, TTX, and L-NNA in vitro, disrupted MMC cycle length, decreased dominant frequency and dominant power of slow waves in vivo. Furthermore, the morphologic studies demonstrated the damage of ICC (ANP group versus control; P = .000), myenteric neurons (ANP group versus control; P = .001) and nNOS immunoreactive neurons (ANP group versus control; P = .000). We also observed a substantial loss in the expression of nNOS protein in muscular layer of the small intestine (ANP group versus control; P = .032). CONCLUSION Our results suggest that the pathogenesis of the small intestinal paralysis in ANP may be related to the deficiencies in ICC and nNOS neurons.
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Kindt S, Vanden Berghe P, Boesmans W, Roosen L, Tack J. Prolonged IL-1beta exposure alters neurotransmitter and electrically induced Ca(2+) responses in the myenteric plexus. Neurogastroenterol Motil 2010; 22:321-e85. [PMID: 19796332 DOI: 10.1111/j.1365-2982.2009.01414.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Infection and inflammatory diseases of the gut results in profound changes of intestinal motor function. Acute administration of the pro-inflammatory cytokine interleukin-1beta (IL-1beta) was shown to have excitatory and neuromodulatory roles in the myenteric plexus. Here we aimed to study the effect of prolonged IL-1beta incubation on the response of myenteric neurones to different stimuli. METHODS Longitudinal muscle myenteric plexus preparations (LMMP's) of the guinea pig jejunum were incubated for 24 h in medium with or without IL-1beta. After loading with Fluo-4, calcium imaging was used to visualize activation of neurones. The response to application of serotonin (5-HT), substance P (SP) and ATP or to electrical fibre tract stimulation (eFTS) was tested. Expression of nNOS, HuD, calbindin and calretinin was compared by immunohistochemistry. KEY RESULTS IL-1beta concentration-dependently influenced the neuronal responsiveness and duration of the [Ca(2+)](i) rises to 5-HT and ATP, while it also affected the Ca(2+)-transient amplitudes induced by 5-HT, ATP and SP. Ca(2+)-transients in response to eFTS were observed in significantly more neurones per ganglion after IL-1beta (10(-10) and 10(-11) mol L(-1)). Peak [Ca(2+)](i) rise after eFTS was concentration-dependently decreased by IL-1beta. The duration of the [Ca(2+)](i) rise after eFTS was prolonged after IL-1beta 10(-12) mol L(-1). IL-1beta (10(-9) mol L(-1)) incubation did not affect the number of nNOS, calretinin and calbindin expressing neurones, nor did it induce neuronal loss (HuD). CONCLUSIONS & INFERENCES In this study, IL-1beta differentially modulates the neuronal response to eFTS and neurotransmitter application in the myenteric plexus of guinea pigs. This cytokine could be implicated in the motility disturbances observed during gastrointestinal inflammation.
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Affiliation(s)
- S Kindt
- Center for Gastroenterological Research, K. U. Leuven, Leuven, Belgium
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16
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Mizutani T, Akiho H, Khan WI, Murao H, Ogino H, Kanayama K, Nakamura K, Takayanagi R. Persistent gut motor dysfunction in a murine model of T-cell-induced enteropathy. Neurogastroenterol Motil 2010; 22:196-203, e65. [PMID: 19735478 DOI: 10.1111/j.1365-2982.2009.01396.x] [Citation(s) in RCA: 12] [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
BACKGROUND Inflammatory bowel disease (IBD) patients in remission often experience irritable bowel syndrome (IBS)-like symptoms. We investigated the mechanism for intestinal muscle hypercontractility seen in T-cell-induced enteropathy in recovery phase. METHODS BALB/c mice were treated with an anti-CD3 antibody (100 microg per mouse) and euthanized at varying days post-treatment to investigate the histological changes, longitudinal smooth muscle cell contraction, cytokines (Th1, Th2 cytokines, TNF-alpha) and serotonin (5-HT)-expressing enterochromaffin cell numbers in the small intestine. The role of 5-HT in anti-CD3 antibody-induced intestinal muscle function in recovery phase was assessed by inhibiting 5-HT synthesis using 4-chloro-DL-phenylalanine (PCPA). KEY RESULTS Small intestinal tissue damage was observed from 24 h after the anti-CD3 antibody injection, but had resolved by day 5. Carbachol-induced smooth muscle cell contractility was significantly increased from 4 h after injection, and this muscle hypercontractility was evident in recovery phase (at day 7). Th2 cytokines (IL-4, IL-13) were significantly increased from 4 h to day 7. 5-HT-expressing cells in the intestine were increased from day 1 to day 7. The 5-HT synthesis inhibitor PCPA decreased the anti-CD3 antibody-induced muscle hypercontractility in recovery phase. CONCLUSIONS & INFERENCES Intestinal muscle hypercontractility in remission is maintained at the smooth muscle cell level. Th2 cytokines and 5-HT in the small intestine contribute to the maintenance of the altered muscle function in recovery phase.
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Affiliation(s)
- T Mizutani
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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Abstract
Cells interact with each other by releasing signalling molecules, which can activate or inactivate target cells. In order to understand how coordination results from this communication, accurate measurements of these signalling molecules are prerequisite. Several different techniques exist to monitor and quantify these compounds, including enzymatic and histochemical assays, electrophysiological and optical recordings. However, there has been little use of electrochemical recordings in gastroenterological research, although these are very fast and sensitive. Electrochemical techniques rely on the simple fact that electroactive molecules can be oxidized at a given potential. The currents, elicited by the oxidation, are directly proportional to the concentration of the compound. In the current issue of Neurogastroenterology and Motility, electrochemical detection was successfully applied to measure nitric oxide (NO) from intestinal preparations. Although there are some important specificity, timing and spatial aspects to consider, this direct NO-probing technique is definitely a great asset to the field of gastrointestinal research and advances our understanding of NO signalling in the intestinal wall.
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Affiliation(s)
- P Vanden Berghe
- Center for Gastroenterological Research, KULeuven, Leuven, Belgium.
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18
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Vanneste G, Van Nassauw L, Kalfin R, Van Colen I, Elinck E, Van Crombruggen K, Timmermans JP, Lefebvre RA. Jejunal cholinergic, nitrergic, and soluble guanylate cyclase activity in postoperative ileus. Surgery 2008; 144:410-26. [PMID: 18707040 DOI: 10.1016/j.surg.2008.05.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2007] [Accepted: 05/17/2008] [Indexed: 01/15/2023]
Abstract
BACKGROUND In animal models of postoperative ileus (POI), inflammation of the intestine plays an important role in the pathogenesis of POI. Changes in alpha(2)-adrenoceptors and nitrergic regulation have been proposed to be implicated. The aim of our study was to investigate the presynaptic alpha(2)-receptor-mediated control of cholinergic nerve activity, the nitrergic nerve activity, and the possible role of soluble guanylate cyclase (sGC) during the inflammatory phase of POI. METHODS Ileus was induced by anesthesia and manipulation of the rat jejunum. Rats were treated with the sGC inhibitors methylene blue or ODQ; nonoperated animals served as controls. After 24 h, plasma and jejunal tissue were collected for biochemical assays, nitric oxide synthase-1 (NOS-1)-immunohistochemistry, acetylcholine (Ach)-release experiments, and muscle tension experiments. RESULTS In all operated animal groups, myeloperoxidase activity was significantly increased, which indicates initiation of an inflammatory response. The alpha(2)-adrenoceptor agonist UK14,304 reduced electrically induced Ach-release similarly in operated and nonoperated animals. In strips of operated animals, electrically induced nitrergic relaxations were decreased, whereas relaxations induced by exogenous nitric oxide (NO) remained unchanged compared with control. The number of myenteric neurons and the percentage of NOS-1-positive neurons were not influenced. Plasmatic cyclic guanosine monophosphate (cGMP) levels were decreased in all operated groups, whereas jejunal cGMP levels were unchanged compared with nonoperated controls; treatment with sGC inhibitors did not reduce plasmatic cGMP levels. CONCLUSIONS This study demonstrates that presynaptic alpha(2)-receptor mediated control of intestinal cholinergic nerve activity is unchanged during manipulation-induced inflammation. However, this inflammation induces impaired nitrergic neurotransmission related to decreased NOS-1 activity in the nitrergic nerves.
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Affiliation(s)
- Gwen Vanneste
- Heymans Institute of Pharmacology, Ghent University, Ghent, Belgium
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Zandecki M, Vanden Berghe P, Depoortere I, Geboes K, Peeters T, Janssens J, Tack J. Characterization of myenteric neuropathy in the jejunum of spontaneously diabetic BB-rats. Neurogastroenterol Motil 2008; 20:818-28. [PMID: 18312542 DOI: 10.1111/j.1365-2982.2008.01091.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Decreased gastric expression and function of neuronal nitric oxide synthase (nNOS) has been proposed as a potential mechanism underlying diabetic gastroparesis. As gastric nNOS expression is vagally controlled, these changes might occur secondarily to vagal neuropathy. In addition, it is unclear whether other inhibitory neurotransmitters are also involved. We used the type 1 diabetic BioBreeding (BB)-rat model to study jejunal motor control and nNOS expression, which is independent of the vagus. Jejunal segments were used for in vitro contractility studies, and measurement of nNOS expression after 8 or 16 weeks of diabetes compared with age- and sex-matched controls. Unlike electrical field stimulation and acetylcholine (ACh)-induced contractions, non-adrenergic non-cholinergic (NANC) relaxations were significantly reduced in diabetic rats. In contrast to control rats, NANC relaxations in diabetic rats were N(omega)-nitro-L-arginine methyl ester (L-NAME) insensitive. Jejunal nNOS expression was significantly decreased in diabetic rats. Both in diabetic and in control animals, L-NAME resistant relaxations were sensitive to P(2)-receptor antagonists. In the jejunum of spontaneously diabetic rats, decreased nitric oxide responsiveness and decreased nNOS protein expression occur while purinergic transmission is unaffected. These findings indicate that nitrergic enteric neuropathy may be a primary dysfunction in diabetes, independent from vagal dysfunction.
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Affiliation(s)
- M Zandecki
- Center for Gastroenterological Research, Catholic University Leuven, Leuven, Belgium
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Aulí M, Nasser Y, Ho W, Burgueño JF, Keenan CM, Romero C, Sharkey KA, Fernández E. Neuromuscular changes in a rat model of colitis. Auton Neurosci 2008; 141:10-21. [PMID: 18534920 DOI: 10.1016/j.autneu.2008.04.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 03/31/2008] [Accepted: 04/10/2008] [Indexed: 12/25/2022]
Abstract
Intracolonic administration of Trichinella spiralis larvae in rats causes colitis with features similar to ulcerative colitis, notably with inflammation predominantly limited to the colonic mucosa. Our aim was to characterize the functional and neurochemical changes occurring within the myenteric (MP) and submucosal plexuses (SMP) during T. spiralis-induced colitis. Infected rats had decreased body weight, altered stool consistency and elevated myeloperoxidase activity, 6 and 14 days post-infection (PI). Responses to acetylcholine and KCl in circular muscle strips were reduced in infected tissues, demonstrating an impairment of contractility. In addition, there was a decrease in spontaneous motor activity and reduced sensitivity to the nitric oxide synthase (NOS) inhibitor L-NOArg, corresponding with a significant reduction in NOS immunoreactive neurons in the MP of infected animals. T. spiralis did not alter the total number of myenteric or submucosal neurons. Substance P innervation of submucosal blood vessels was reduced after infection, as were submucosal calretinin and calbindin immunoreactive neurons. No changes in choline acetyltransferase and calcitonin gene-related peptide immunoreactivity were observed. T. spiralis-induced colitis causes profound neuromuscular adaptations. The reduction in NOS neurons appears to underlie changes in motility.
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Affiliation(s)
- Mariona Aulí
- Department of Cell Biology, Physiology and Immunology, Veterinary Faculty, Universitat Autònoma de Barcelona, Spain
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Soares PMG, Mota JMSC, Gomes AS, Oliveira RB, Assreuy AMS, Brito GAC, Santos AA, Ribeiro RA, Souza MHLP. Gastrointestinal dysmotility in 5-fluorouracil-induced intestinal mucositis outlasts inflammatory process resolution. Cancer Chemother Pharmacol 2008; 63:91-8. [PMID: 18324404 DOI: 10.1007/s00280-008-0715-9] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Accepted: 02/17/2008] [Indexed: 12/22/2022]
Abstract
AIM To evaluate gastrointestinal motility during 5-fluorouracil (5-FU)-induced intestinal mucositis. MATERIALS AND METHODS Wistar rats received 5-FU (150 mg kg(-1), i.p.) or saline. After the 1st, 3rd, 5th, 15th and 30th day, sections of duodenum, jejunum and ileum were removed for assessment of epithelial damage, apoptotic and mitotic indexes, MPO activity and GSH concentration. In order to study gastrointestinal motility, on the 3rd or 15th day after 5-FU treatment, gastric emptying in vivo was measured by scintilographic method, and stomach or duodenal smooth muscle contractions induced by CCh were evaluated in vitro. RESULTS On the third day of treatment, 5-FU induced a significant villi shortening, an increase in crypt depth and intestinal MPO activity and a decrease in villus/crypt ratio and GSH concentration. On the first day after 5-FU there was an increase in the apoptosis index and a decrease in the mitosis index in all intestinal segments. After the 15th day of 5-FU treatment, a complete reversion of all these parameters was observed. There was a delay in gastric emptying in vivo and a significant increase in gastric fundus and duodenum smooth muscle contraction, after both the 3rd and 15th day. CONCLUSION 5-FU-induced gastrointestinal dysmotility outlasts intestinal mucositis.
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Affiliation(s)
- Pedro M G Soares
- Centro de Biomedicina, Faculdade de Medicina, Universidade Federal do Ceará, Rodolfo Teófilo, Fortaleza, Brazil
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Identification and immunohistochemical characterization of colospinal afferent neurons in the rat. Neuroscience 2008; 153:803-13. [PMID: 18424003 DOI: 10.1016/j.neuroscience.2008.02.046] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Revised: 02/13/2008] [Accepted: 02/14/2008] [Indexed: 01/18/2023]
Abstract
The classification, morphology and function of enteric neurons have been extensively studied in the small and large intestine. However, little is known about enteric neurons that directly project to the CNS. Previous studies have identified these unique neurons in the rectum, rectospinal neurons, but little was done to characterize them. Therefore, the aim of this study was to identify and characterize enteric neurons in the rat colon that directly project to the CNS by using retrograde neuronal tracing and immunohistochemistry. By applying the retrograde tracers 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate (DiI) and Fluorogold (FG) to the L6/S1 segments of the spinal cord, we identified these neurons in both the myenteric and submucosal plexuses of the colon. These neurons were immunoreactive for neurofilament (NF) a marker for Adelta-fibers and isolectin-B4 (IB(4)) a marker for C-fibers. These neurons expressed the enzyme neuronal nitric oxide synthase (nNOS) as well as peptides associated with sensory neurons such as substance P (SP) and vasoactive intestinal polypeptide (VIP) but did not express calcitonin gene-related peptide (CGRP). The N-methyl-D-aspartate (NMDA) receptor subunits NR1 and NR2D and proteinase-activated receptor-2 (PAR2) were also found in these neurons. However they did not express the transient receptor potential receptor V1 (TRPV1) or neurokinin 1 receptor (NK1). The expression of the peptides and receptors suggests that there are at least two separate populations of neurons projecting from the colon to the CNS. The data suggest that these colospinal afferent neurons (CANs) might be involved in nociception. Whether sensory information from CANs is perceived by the animal or is part of the parasympathetic reflex is currently not known.
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