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Xie X, Geng C, Li X, Liao J, Li Y, Guo Y, Wang C. Roles of gastrointestinal polypeptides in intestinal barrier regulation. Peptides 2022; 151:170753. [PMID: 35114316 DOI: 10.1016/j.peptides.2022.170753] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 01/29/2022] [Accepted: 01/30/2022] [Indexed: 12/17/2022]
Abstract
The intestinal barrier is a dynamic entity that is organized as a multilayer system and includes various intracellular and extracellular elements. The gut barrier functions in a coordinated manner to impede the passage of antigens, toxins, and microbiome components and simultaneously preserves the balanced development of the epithelial barrier and the immune system and the acquisition of tolerance to dietary antigens and intestinal pathogens.Numerous scientific studies have shown a significant association between gut barrier damage and gastrointestinal and extraintestinal diseases such as inflammatory bowel disease, celiac disease and hepatic fibrosis. Various internal and external factors regulate the intestinal barrier. Gastrointestinal peptides originate from enteroendocrine cells in the luminal digestive tract and are critical gut barrier regulators. Recent studies have demonstrated that gastrointestinal peptides have a therapeutic effect on digestive tract diseases, enhancing epithelial barrier activity and restoring the gut barrier. This review demonstrates the roles and mechanisms of gastrointestinal polypeptides, especially somatostatin (SST) and vasoactive intestinal peptide (VIP), in intestinal barrier regulation.
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Affiliation(s)
- Xiaoxi Xie
- Department of Gastroenterology, West China Hospital of Sichuan University, Chengdu, China
| | - Chong Geng
- Department of Gastroenterology, West China Hospital of Sichuan University, Chengdu, China
| | - Xiao Li
- Department of Gastroenterology, West China Hospital of Sichuan University, Chengdu, China; Division of Digestive Diseases, West China Hospital of Sichuan University, Chengdu, China
| | - Juan Liao
- Non-communicable Diseases Research Center, West China-PUMC C.C. Chen Institute of Health, Sichuan University, Chengdu, China
| | - Yanni Li
- Department of Gastroenterology, West China Hospital of Sichuan University, Chengdu, China
| | - Yaoyu Guo
- Department of Gastroenterology, West China Hospital of Sichuan University, Chengdu, China
| | - Chunhui Wang
- Department of Gastroenterology, West China Hospital of Sichuan University, Chengdu, China.
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Alterations in Small Intestine and Liver Morphology, Immunolocalization of Leptin, Ghrelin and Nesfatin-1 as Well as Immunoexpression of Tight Junction Proteins in Intestinal Mucosa after Gastrectomy in Rat Model. J Clin Med 2021; 10:jcm10020272. [PMID: 33450994 PMCID: PMC7828391 DOI: 10.3390/jcm10020272] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/01/2021] [Accepted: 01/11/2021] [Indexed: 02/07/2023] Open
Abstract
The stomach is responsible for the processing of nutrients as well as for the secretion of various hormones which are involved in many activities throughout the gastrointestinal tract. Experimental adult male Wistar rats (n = 6) underwent a modified gastrectomy, while control rats (n = 6) were sham-operated. After six weeks, changes in small intestine (including histomorphometrical parameters of the enteric nervous plexuses) and liver morphology, immunolocalization of leptin, ghrelin and nesfatin-1 as well as proteins forming adherens and tight junctions (E-cadherin, zonula occludens-1, occludin, marvelD3) in intestinal mucosa were evaluated. A number of effects on small intestine morphology, enteric nervous system ganglia, hormones and proteins expression were found, showing intestinal enteroplasticity and neuroplasticity associated with changes in gastrointestinal tract condition. The functional changes in intestinal mucosa and the enteric nervous system could be responsible for the altered intestinal barrier and hormonal responses following gastrectomy. The results suggest that more complicated regulatory mechanisms than that of compensatory mucosal hypertrophy alone are involved.
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Effect of Acrylamide Supplementation on the Population of Vasoactive Intestinal Peptide (VIP)-Like Immunoreactive Neurons in the Porcine Small Intestine. Int J Mol Sci 2020; 21:ijms21249691. [PMID: 33353157 PMCID: PMC7765847 DOI: 10.3390/ijms21249691] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/08/2020] [Accepted: 12/16/2020] [Indexed: 12/14/2022] Open
Abstract
Acrylamide is one of the harmful substances present in food. The present study aimed to establish the effect of acrylamide supplementation in tolerable daily intake (TDI) dose (0.5 µg/kg b.w./day) and a dose ten times higher than TDI (5 µg/kg b.w./day) on the population of vasoactive intestinal peptide-like immunoreactive (VIP-LI) neurons in the porcine small intestine and the degree of the co-localization of VIP with other neuroactive substances (neuronal nitric oxide synthase (nNOS), substance P (SP), and cocaine- and amphetamine-regulated transcript peptide (CART)). In our work, 15 Danish landrace gilts (5 in each experimental group) received capsules (empty or with low or high doses of acrylamide) for a period of 28 days with their morning feeding. Using double immunofluorescence staining, we established that acrylamide supplementation increased the number of neurons showing immunoreactivity towards VIP in all types of enteric nervous system (ENS) plexuses and fragments of the small intestine studied. Moreover, both doses of acrylamide led to changes in the degree of co-localization of VIP with nNOS, SP, and CART in intramural neurons. The observed changes may be the adaptation of neurons to local inflammation, oxidative stress, or the direct toxic effects of acrylamide on intestinal neurons, also referred to as neuronal plasticity.
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Abstract
PURPOSE OF REVIEW The gut barrier serves as the primary interface between the environment and host in terms of surface area and complexity. Luminal chemosensing is a term used to describe how small molecules in the gut lumen interact with the host through surface receptors or via transport into the subepithelial space. In this review, we have summarized recent advances in the understanding of the luminal chemosensory system in the gastroduodenal epithelium consisting of enterocytes, enteroendocrine, and tuft cells, with particular emphasis on how chemosensing affects mucosal protective responses and the metabolic syndrome. RECENT FINDINGS Recent single-cell RNA sequencing provides detailed cell type-specific expression of chemosensory receptors and other bioactive molecules as well as cell lineages; some are similar to lingual taste cells whereas some are gut specific. Gut luminal chemosensing is not only important for the local or remote regulation of gut function, but also contributes to the systemic regulation of metabolism, energy balance, and food intake. We will discuss the chemosensory mechanisms of the proximal intestine, in particular to gastric acid, with a focus on the cell types and receptors involved in chemosensing, with emphasis on the rare chemosensory cells termed tuft cells. We will also discuss the chemosensory functions of intestinal ectoenzymes and bacterial components (e.g., lipopolysaccharide) as well as how they affect mucosal function through altering the gut-hormonal-neural axis. SUMMARY Recent updates in luminal chemosensing by different chemosensory cells have provided new possibilities for identifying novel molecular targets for the treatment of mucosal injury, metabolic disorders, and abnormal visceral sensation.
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Afroze F, Bloom S, Bech P, Ahmed T, Sarker SA, Clemens JD, Islam F, Nalin D. Cholera and Pancreatic Cholera: Is VIP the Common Pathophysiologic Factor? Trop Med Infect Dis 2020; 5:tropicalmed5030111. [PMID: 32630790 PMCID: PMC7559706 DOI: 10.3390/tropicalmed5030111] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 06/20/2020] [Accepted: 06/30/2020] [Indexed: 12/14/2022] Open
Abstract
Background: Cholera remains a major global health problem, causing high output diarrhea leading to severe dehydration and shock in developing countries. We aimed to determine whether vasoactive intestinal polypeptide (VIP), the mediator of pancreatic cholera syndrome, has a role in the pathophysiology of human cholera. Methods: We conducted a prospective observational study of cholera cases hospitalized with severe dehydration. Plasma and stool water levels of VIP were measured just after admission, after complete rehydration (3–4 h), at 24 h post-rehydration and at discharge after diarrhea ceased. Results: In total, 23 cholera patients were examined between January and August 2018. The geometric mean of stool VIP (sVIP) and plasma VIP (pVIP) on admission were 207.67 and 8.34 pmol/L, respectively. pVIP values were all within the normal range (</= 30 pcmol/L); however, sVIP levels were very high at all timepoints, though less so just after rehydration. In multivariable GEE models, after adjustment for covariates, sVIP levels were significantly associated with duration of hospitalization (p = 0.026), total stool volume (p = 0.023) as well as stool output in the first 24 h (p = 0.013). Conclusions: The data suggest that VIP, which is released by intestinal nerves, may play an important role in human choleragenesis, and inhibitors of intestinal VIP merit testing for potential therapeutic benefits.
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Affiliation(s)
- Farzana Afroze
- International Centre for Diarrheal Disease Research (icddr,b), Dhaka 1212, Bangladesh; (F.A.); (T.A.); (S.A.S.); (J.D.C.); (F.I.)
| | - Steven Bloom
- North West London Pathology Consortium, Hammersmith Hospital, Imperial College London, Du Cane Road, London W12 0NN, UK; (S.B.); (P.B.)
| | - Paul Bech
- North West London Pathology Consortium, Hammersmith Hospital, Imperial College London, Du Cane Road, London W12 0NN, UK; (S.B.); (P.B.)
| | - Tahmeed Ahmed
- International Centre for Diarrheal Disease Research (icddr,b), Dhaka 1212, Bangladesh; (F.A.); (T.A.); (S.A.S.); (J.D.C.); (F.I.)
| | - Shafiqul Alam Sarker
- International Centre for Diarrheal Disease Research (icddr,b), Dhaka 1212, Bangladesh; (F.A.); (T.A.); (S.A.S.); (J.D.C.); (F.I.)
| | - John D. Clemens
- International Centre for Diarrheal Disease Research (icddr,b), Dhaka 1212, Bangladesh; (F.A.); (T.A.); (S.A.S.); (J.D.C.); (F.I.)
| | - Farhana Islam
- International Centre for Diarrheal Disease Research (icddr,b), Dhaka 1212, Bangladesh; (F.A.); (T.A.); (S.A.S.); (J.D.C.); (F.I.)
| | - David Nalin
- Department of Immunology and Microbial Diseases, Albany Medical College, Albany, NY 12208, USA
- Correspondence: ; Tel.: +1-484-653-9945; Fax: +1-610-4301-6004
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Das S, Gordián-Vélez WJ, Ledebur HC, Mourkioti F, Rompolas P, Chen HI, Serruya MD, Cullen DK. Innervation: the missing link for biofabricated tissues and organs. NPJ Regen Med 2020; 5:11. [PMID: 32550009 PMCID: PMC7275031 DOI: 10.1038/s41536-020-0096-1] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 04/29/2020] [Indexed: 12/15/2022] Open
Abstract
Innervation plays a pivotal role as a driver of tissue and organ development as well as a means for their functional control and modulation. Therefore, innervation should be carefully considered throughout the process of biofabrication of engineered tissues and organs. Unfortunately, innervation has generally been overlooked in most non-neural tissue engineering applications, in part due to the intrinsic complexity of building organs containing heterogeneous native cell types and structures. To achieve proper innervation of engineered tissues and organs, specific host axon populations typically need to be precisely driven to appropriate location(s) within the construct, often over long distances. As such, neural tissue engineering and/or axon guidance strategies should be a necessary adjunct to most organogenesis endeavors across multiple tissue and organ systems. To address this challenge, our team is actively building axon-based "living scaffolds" that may physically wire in during organ development in bioreactors and/or serve as a substrate to effectively drive targeted long-distance growth and integration of host axons after implantation. This article reviews the neuroanatomy and the role of innervation in the functional regulation of cardiac, skeletal, and smooth muscle tissue and highlights potential strategies to promote innervation of biofabricated engineered muscles, as well as the use of "living scaffolds" in this endeavor for both in vitro and in vivo applications. We assert that innervation should be included as a necessary component for tissue and organ biofabrication, and that strategies to orchestrate host axonal integration are advantageous to ensure proper function, tolerance, assimilation, and bio-regulation with the recipient post-implant.
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Affiliation(s)
- Suradip Das
- Center for Brain Injury & Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA USA
- Center for Neurotrauma, Neurodegeneration & Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA USA
| | - Wisberty J. Gordián-Vélez
- Center for Brain Injury & Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA USA
- Center for Neurotrauma, Neurodegeneration & Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA USA
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA USA
| | | | - Foteini Mourkioti
- Department of Orthopedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA USA
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA USA
| | - Panteleimon Rompolas
- Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA USA
| | - H. Isaac Chen
- Center for Brain Injury & Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA USA
- Center for Neurotrauma, Neurodegeneration & Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA USA
| | - Mijail D. Serruya
- Center for Neurotrauma, Neurodegeneration & Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA USA
- Department of Neurology, Thomas Jefferson University, Philadelphia, PA USA
| | - D. Kacy Cullen
- Center for Brain Injury & Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA USA
- Center for Neurotrauma, Neurodegeneration & Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA USA
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA USA
- Axonova Medical, LLC., Philadelphia, PA USA
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Iwasaki M, Akiba Y, Kaunitz JD. Recent advances in vasoactive intestinal peptide physiology and pathophysiology: focus on the gastrointestinal system. F1000Res 2019; 8. [PMID: 31559013 PMCID: PMC6743256 DOI: 10.12688/f1000research.18039.1] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/05/2019] [Indexed: 12/11/2022] Open
Abstract
Vasoactive intestinal peptide (VIP), a gut peptide hormone originally reported as a vasodilator in 1970, has multiple physiological and pathological effects on development, growth, and the control of neuronal, epithelial, and endocrine cell functions that in turn regulate ion secretion, nutrient absorption, gut motility, glycemic control, carcinogenesis, immune responses, and circadian rhythms. Genetic ablation of this peptide and its receptors in mice also provides new insights into the contribution of VIP towards physiological signaling and the pathogenesis of related diseases. Here, we discuss the impact of VIP on gastrointestinal function and diseases based on recent findings, also providing insight into its possible therapeutic application to diabetes, autoimmune diseases and cancer.
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Affiliation(s)
- Mari Iwasaki
- Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA
| | - Yasutada Akiba
- Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA.,Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Jonathan D Kaunitz
- Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA.,Departments of Medicine and Surgery, UCLA School of Medicine, Los Angeles, CA, USA
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Kuwahara A, Kuwahara Y, Kato I, Kawaguchi K, Harata D, Asano S, Inui T, Marunaka Y. Xenin-25 induces anion secretion by activating noncholinergic secretomotor neurons in the rat ileum. Am J Physiol Gastrointest Liver Physiol 2019; 316:G785-G796. [PMID: 30978113 DOI: 10.1152/ajpgi.00333.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Xenin-25 is a neurotensin-like peptide that is secreted by enteroendocrine cells in the small intestine. Xenin-8 is reported to augment duodenal anion secretion by activating afferent neural pathways. The intrinsic neuronal circuits mediating the xenin-25-induced anion secretion were characterized using the Ussing-chambered, mucosa-submucosa preparation from the rat ileum. Serosal application of xenin-25 increased the short-circuit current in a concentration-dependent manner. The responses were abolished by the combination of Cl--free and HCO3- -free solutions. The responses were almost completely blocked by TTX (10-6 M) but not by atropine (10-5 M) or hexamethonium (10-4 M). The selective antagonists for neurotensin receptor 1 (NTSR1), neurokinin 1 (NK1), vasoactive intestinal polypeptide (VIP) receptors 1 and 2 (VPAC1 and VPAC2, respectively), and capsaicin, but not 5-hydroxyltryptamine receptors 3 and 4 (5-HT3 and 5-HT4), NTSR2, and A803467, inhibited the responses to xenin-25. The expression of VIP receptors (Vipr) in rat ileum was examined using RT-PCR. The Vipr1 PCR products were detected in the submucosal plexus and mucosa. Immunohistochemical staining showed the colocalization of NTSR1 and NK1 with substance P (SP)- and calbindin-immunoreactive neurons in the submucosal plexus, respectively. In addition, NK1 was colocalized with noncholinergic VIP secretomotor neurons. Based on the results from the present study, xenin-25-induced Cl-/ HCO3- secretion is involved in NTSR1 activation on intrinsic and extrinsic afferent neurons, followed by the release of SP and subsequent activation of NK1 expressed on noncholinergic VIP secretomotor neurons. Finally, the secreted VIP may activate VPAC1 on epithelial cells to induce Cl-/ HCO3- secretion in the rat ileum. Activation of noncholinergic VIP secretomotor neurons by intrinsic primary afferent neurons and extrinsic afferent neurons by postprandially released xenin-25 may account for most of the neurogenic secretory response induced by xenin-25. NEW & NOTEWORTHY This study is the first to investigate the intrinsic neuronal circuit responsible for xenin-25-induced anion secretion in the rat small intestine. We have found that nutrient-stimulated xenin-25 release may activate noncholinergic vasoactive intestinal polypeptide (VIP) secretomotor neurons to promote Cl-/ HCO3- secretion through the activation of VIP receptor 1 on epithelial cells. Moreover, the xenin-25-induced secretory responses are mainly linked with intrinsic primary afferent neurons, which are involved in the activation of neurotensin receptor 1 and neurokinin 1 receptor.
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Affiliation(s)
- Atsukazu Kuwahara
- Research Unit for Epithelial Physiology, Research Organization of Science and Technology, Ritsumeikan University , Kusatsu , Japan.,Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine , Kyoto , Japan.,Research Center for Drug Discovery and Pharmaceutical Development Science, Research Organization of Science and Technology, Ritsumeikan University , Kusatsu , Japan
| | - Yuko Kuwahara
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine , Kyoto , Japan
| | - Ikuo Kato
- Department of Medical Biochemistry, Kobe Pharmaceutical University , Kobe , Japan
| | - Kotoku Kawaguchi
- Department of Molecular Physiology, College of Pharmaceutical Sciences, Ritsumeikan University , Kusatsu , Japan
| | - Daiki Harata
- Department of Molecular Physiology, College of Pharmaceutical Sciences, Ritsumeikan University , Kusatsu , Japan
| | - Shinji Asano
- Department of Molecular Physiology, College of Pharmaceutical Sciences, Ritsumeikan University , Kusatsu , Japan
| | | | - Yoshinori Marunaka
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine , Kyoto , Japan.,Research Center for Drug Discovery and Pharmaceutical Development Science, Research Organization of Science and Technology, Ritsumeikan University , Kusatsu , Japan.,Research Institute for Clinical Physiology, Kyoto Industrial Health Association , Kyoto , Japan
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Zhu ZC, Wang HB, Yan XQ, Yang J, Duan XF, Bian HQ, Kuang HF. Serum substance P and vasoactive intestinal peptide levels in infants with acute intussusception. J Int Med Res 2019; 47:2446-2451. [PMID: 31006358 PMCID: PMC6567688 DOI: 10.1177/0300060519844401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Objective We aimed to investigate the role of the intestinal neurotransmitters vasoactive intestinal peptide (VIP) and substance P (SP) at different time points in infants with acute intussusception. Methods Thirty patients who were diagnosed with acute intussusception were enrolled in the study and classified as the experimental group. Another 30 patients with an indirect inguinal hernia who had no intestinal injury were included as the control group. Serum SP and VIP levels at different time points, including pre- and postoperation, were detected by enzyme-linked immunosorbent assay and compared between the two groups. Results Serum SP levels in patients with acute intussusception were significantly higher than those in controls. However, with recovery of acute intussusception, SP levels gradually decreased after treatment. Serum VIP levels in patients with acute intussusception were significantly lower than those in controls. However, with recovery of acute intussusception, VIP levels gradually increased after treatment. Conclusions SP and VIP levels may have a potential relationship with the pathogenetic process of intussusception.
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Affiliation(s)
- Zhen-Chuang Zhu
- Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Hai-Bin Wang
- Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Xue-Qiang Yan
- Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Jun Yang
- Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Xu-Fei Duan
- Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Hong-Qiang Bian
- Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Hou-Fang Kuang
- Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
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10
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Fung C, Koussoulas K, Unterweger P, Allen AM, Bornstein JC, Foong JPP. Cholinergic Submucosal Neurons Display Increased Excitability Following in Vivo Cholera Toxin Exposure in Mouse Ileum. Front Physiol 2018; 9:260. [PMID: 29618987 PMCID: PMC5871806 DOI: 10.3389/fphys.2018.00260] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 03/06/2018] [Indexed: 12/16/2022] Open
Abstract
Cholera-induced hypersecretion causes dehydration and death if untreated. Cholera toxin (CT) partly acts via the enteric nervous system (ENS) and induces long-lasting changes to enteric neuronal excitability following initial exposure, but the specific circuitry involved remains unclear. We examined this by first incubating CT or saline (control) in mouse ileal loops in vivo for 3.5 h and then assessed neuronal excitability in vitro using Ca2+ imaging and immunolabeling for the activity-dependent markers cFos and pCREB. Mice from a C57BL6 background, including Wnt1-Cre;R26R-GCaMP3 mice which express the fluorescent Ca2+ indicator GCaMP3 in its ENS, were used. Ca2+-imaging using this mouse model is a robust, high-throughput method which allowed us to examine the activity of numerous enteric neurons simultaneously and post-hoc immunohistochemistry enabled the neurochemical identification of the active neurons. Together, this provided novel insight into the CT-affected circuitry that was previously impossible to attain at such an accelerated pace. Ussing chamber measurements of electrogenic ion secretion showed that CT-treated preparations had higher basal secretion than controls. Recordings of Ca2+ activity from the submucous plexus showed that increased numbers of neurons were spontaneously active in CT-incubated tissue (control: 4/149; CT: 32/160; Fisher's exact test, P < 0.0001) and that cholinergic neurons were more responsive to electrical (single pulse and train of 20 pulses) or nicotinic (1,1-dimethyl-4-phenylpiperazinium (DMPP; 10 μM) stimulation. Expression of the neuronal activity marker, pCREB, was also increased in the CT-treated submucous plexus neurons. c-Fos expression and spontaneous fast excitatory postsynaptic potentials (EPSPs), recorded by intracellular electrodes, were increased by CT exposure in a small subset of myenteric neurons. However, the effect of CT on the myenteric plexus is less clear as spontaneous Ca2+ activity and electrical- or nicotinic-evoked Ca2+ responses were reduced. Thus, in a model where CT exposure evokes hypersecretion, we observed sustained activation of cholinergic secretomotor neuron activity in the submucous plexus, pointing to involvement of these neurons in the overall response to CT.
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Affiliation(s)
- Candice Fung
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Katerina Koussoulas
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Petra Unterweger
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Andrew M Allen
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia.,Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Joel C Bornstein
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Jaime P P Foong
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia
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11
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Giancola F, Torresan F, Repossi R, Bianco F, Latorre R, Ioannou A, Guarino M, Volta U, Clavenzani P, Mazzoni M, Chiocchetti R, Bazzoli F, Travagli RA, Sternini C, De Giorgio R. Downregulation of neuronal vasoactive intestinal polypeptide in Parkinson's disease and chronic constipation. Neurogastroenterol Motil 2017; 29:10.1111/nmo.12995. [PMID: 27891695 PMCID: PMC5393951 DOI: 10.1111/nmo.12995] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 10/21/2016] [Indexed: 02/06/2023]
Abstract
BACKGROUND Chronic constipation (CC) is a common and severe gastrointestinal complaint in Parkinson's disease (PD), but its pathogenesis remains poorly understood. This study evaluated functionally distinct submucosal neurons in relation to colonic motility and anorectal function in PD patients with constipation (PD/CC) vs both CC and controls. METHODS Twenty-nine PD/CC and 10 Rome III-defined CC patients were enrolled. Twenty asymptomatic age-sex matched subjects served as controls. Colonic transit time measurement and conventional anorectal manometry were evaluated in PD/CC and CC patients. Colonoscopy was performed in all three groups. Colonic submucosal whole mounts from PD/CC, CC, and controls were processed for immunohistochemistry with antibodies for vasoactive intestinal polypeptide (VIP) and peripheral choline acetyltransferase, markers for functionally distinct submucosal neurons. The mRNA expression of VIP and its receptors were also assessed. KEY RESULTS Four subgroups of PD/CC patients were identified: delayed colonic transit plus altered anorectal manometry (65%); delayed colonic transit (13%); altered manometric pattern (13%); and no transit and manometric impairment (9%). There were no differences in the number of neurons/ganglion between PD/CC vs CC or vs controls. A reduced number of submucosal neurons containing VIP immunoreactivity was found in PD/CC vs controls (P<.05). VIP, VIPR1, and VIPR2 mRNA expression was significantly reduced in PD/CC vs CC and controls (P<.05). CONCLUSIONS AND INFERENCES Colonic motor and rectal sensory functions are impaired in most PD/CC patients. These abnormalities are associated with a decreased VIP expression in submucosal neurons. Both sensory-motor abnormalities and neurally mediated motor and secretory mechanisms are likely to contribute to PD/CC pathophysiology.
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Affiliation(s)
- Fiorella Giancola
- Department of Medical and Surgical Sciences, University of Bologna, and St. Orsola-Malpighi Hospital, Bologna, Italy
- Department of Veterinary Medical Sciences, University of Bologna, Italy
| | - Francesco Torresan
- Department of Medical and Surgical Sciences, University of Bologna, and St. Orsola-Malpighi Hospital, Bologna, Italy
| | - Roberta Repossi
- Department of Medical and Surgical Sciences, University of Bologna, and St. Orsola-Malpighi Hospital, Bologna, Italy
| | - Francesca Bianco
- Department of Medical and Surgical Sciences, University of Bologna, and St. Orsola-Malpighi Hospital, Bologna, Italy
- Department of Veterinary Medical Sciences, University of Bologna, Italy
| | - Rocco Latorre
- Department of Medical and Surgical Sciences, University of Bologna, and St. Orsola-Malpighi Hospital, Bologna, Italy
| | - Alexandros Ioannou
- Department of Medical and Surgical Sciences, University of Bologna, and St. Orsola-Malpighi Hospital, Bologna, Italy
| | - Maria Guarino
- Neurology Unit, St. Orsola-Malpighi Hospital, Bologna, Italy
| | - Umberto Volta
- Department of Medical and Surgical Sciences, University of Bologna, and St. Orsola-Malpighi Hospital, Bologna, Italy
| | - Paolo Clavenzani
- Department of Veterinary Medical Sciences, University of Bologna, Italy
| | - Maurizio Mazzoni
- Department of Veterinary Medical Sciences, University of Bologna, Italy
| | | | - Franco Bazzoli
- Department of Medical and Surgical Sciences, University of Bologna, and St. Orsola-Malpighi Hospital, Bologna, Italy
| | - R. Alberto Travagli
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA, USA
| | - Catia Sternini
- CURE Digestive Diseases Research Center, Digestive Diseases Division, Departments of Medicine and Neurobiology, University of California Los Angeles, David Geffen School of Medicine, Los Angeles, CA, USA
| | - Roberto De Giorgio
- Department of Medical and Surgical Sciences, University of Bologna, and St. Orsola-Malpighi Hospital, Bologna, Italy
- Centro Unificato di Ricerca Biomedica Applicata, Bologna, Italy
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12
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Fung C, Boesmans W, Cirillo C, Foong JPP, Bornstein JC, Vanden Berghe P. VPAC Receptor Subtypes Tune Purinergic Neuron-to-Glia Communication in the Murine Submucosal Plexus. Front Cell Neurosci 2017; 11:118. [PMID: 28487635 PMCID: PMC5403822 DOI: 10.3389/fncel.2017.00118] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 04/10/2017] [Indexed: 12/20/2022] Open
Abstract
The enteric nervous system (ENS) situated within the gastrointestinal tract comprises an intricate network of neurons and glia which together regulate intestinal function. The exact neuro-glial circuitry and the signaling molecules involved are yet to be fully elucidated. Vasoactive intestinal peptide (VIP) is one of the main neurotransmitters in the gut, and is important for regulating intestinal secretion and motility. However, the role of VIP and its VPAC receptors within the enteric circuitry is not well understood. We investigated this in the submucosal plexus of mouse jejunum using calcium (Ca2+)-imaging. Local VIP application induced Ca2+-transients primarily in neurons and these were inhibited by VPAC1- and VPAC2-antagonists (PG 99-269 and PG 99-465 respectively). These VIP-evoked neural Ca2+-transients were also inhibited by tetrodotoxin (TTX), indicating that they were secondary to action potential generation. Surprisingly, VIP induced Ca2+-transients in glia in the presence of the VPAC2 antagonist. Further, selective VPAC1 receptor activation with the agonist ([K15, R16, L27]VIP(1-7)/GRF(8-27)) predominantly evoked glial responses. However, VPAC1-immunoreactivity did not colocalize with the glial marker glial fibrillary acidic protein (GFAP). Rather, VPAC1 expression was found on cholinergic submucosal neurons and nerve fibers. This suggests that glial responses observed were secondary to neuronal activation. Trains of electrical stimuli were applied to fiber tracts to induce endogenous VIP release. Delayed glial responses were evoked when the VPAC2 antagonist was present. These findings support the presence of an intrinsic VIP/VPAC-initiated neuron-to-glia signaling pathway. VPAC1 agonist-evoked glial responses were inhibited by purinergic antagonists (PPADS and MRS2179), thus demonstrating the involvement of P2Y1 receptors. Collectively, we showed that neurally-released VIP can activate neurons expressing VPAC1 and/or VPAC2 receptors to modulate purine-release onto glia. Selective VPAC1 activation evokes a glial response, whereas VPAC2 receptors may act to inhibit this response. Thus, we identified a component of an enteric neuron-glia circuit that is fine-tuned by endogenous VIP acting through VPAC1- and VPAC2-mediated pathways.
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Affiliation(s)
- Candice Fung
- Department of Physiology, The University of MelbourneParkville, VIC, Australia.,Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
| | - Werend Boesmans
- Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
| | - Carla Cirillo
- Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
| | - Jaime P P Foong
- Department of Physiology, The University of MelbourneParkville, VIC, Australia
| | - Joel C Bornstein
- Department of Physiology, The University of MelbourneParkville, VIC, Australia
| | - Pieter Vanden Berghe
- Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
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13
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Liu GX, Gan HT. Effect of enteric nervous system on intestinal epithelial barrier in inflammatory bowel disease. Shijie Huaren Xiaohua Zazhi 2017; 25:107-113. [DOI: 10.11569/wcjd.v25.i2.107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Both enteric nervous system and intestinal epithelial barrier are vital components to ensure gut homeostasis. Recent studies have shown the implications of their close relationship for gut health and disease. By secreting neurotransmitters, the enteric nervous system plays an important role in regulating the epithelial barrier function. Meanwhile, communicating largely through the vagal nerve, the central nervous system could also interact with the intestinal epithelium through the enteric nervous system. Although the etiology and pathogenesis of inflammatory bowel disease remain elusive, increasing evidence has shown that the dysregulation of enteric nervous system affects both epithelial integrity and barrier function, which contributes to the occurrence and development of inflammatory bowel disease. This review will summarize the current knowledge regarding the effect of enteric nervous system on intestinal epithelial barrier and its implication in the development of inflammatory bowel disease.
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14
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Galligan JJ, Sternini C. Insights into the Role of Opioid Receptors in the GI Tract: Experimental Evidence and Therapeutic Relevance. Handb Exp Pharmacol 2017; 239:363-378. [PMID: 28204957 PMCID: PMC6310692 DOI: 10.1007/164_2016_116] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Opioid drugs are prescribed extensively for pain treatment but when used chronically they induce constipation that can progress to opioid-induced bowel dysfunction. Opioid drugs interact with three classes of opioid receptors: mu opioid receptors (MORs), delta opioid receptors (DOR), and kappa opioid receptors (KORs), but opioid drugs mostly target the MORs. Upon stimulation, opioid receptors couple to inhibitory Gi/Go proteins that activate or inhibit downstream effector proteins. MOR and DOR couple to inhibition of adenylate cyclase and voltage-gated Ca2+ channels and to activation of K+ channels resulting in reduced neuronal activity and neurotransmitter release. KORs couple to inhibition of Ca2+ channels and neurotransmitter release. In the gastrointestinal tract, opioid receptors are localized to enteric neurons, interstitial cells of Cajal, and immune cells. In humans, MOR, DOR, and KOR link to inhibition of acetylcholine release from enteric interneurons and motor neurons and purine/nitric oxide release from inhibitory motor neurons causing inhibition of propulsive motility patterns. MOR and DOR activation also results in inhibition of submucosal secretomotor neurons reducing active Cl- secretion and passive water movement into the colonic lumen. Together, these effects on motility and secretion account for the constipation caused by opioid receptor agonists. Tolerance develops to the analgesic effects of opioid receptor agonists but not to the constipating actions. This may be due to differences in trafficking and downstream signaling in enteric nerves in the colon compared to the small intestine and in neuronal pain pathways. Further studies of differential opioid receptor desensitization and tolerance in subsets of enteric neurons may identify new drug or other treatment strategies of opioid-induced bowel dysfunction.
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Affiliation(s)
- James J Galligan
- Department of Pharmacology and Toxicology and the Neuroscience Program, Michigan State University, 293 Farm Lane, Giltner Hall 108, East Lansing, MI, 48824, USA.
| | - Catia Sternini
- CURE/DDRC, Vatche and Tamar Manoukian Division of Digestive Diseases, Departments of Medicine and Neurobiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, 90095, USA
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15
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Filpa V, Moro E, Protasoni M, Crema F, Frigo G, Giaroni C. Role of glutamatergic neurotransmission in the enteric nervous system and brain-gut axis in health and disease. Neuropharmacology 2016; 111:14-33. [PMID: 27561972 DOI: 10.1016/j.neuropharm.2016.08.024] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 07/18/2016] [Accepted: 08/18/2016] [Indexed: 02/07/2023]
Abstract
Several studies have been carried out in the last 30 years in the attempt to clarify the possible role of glutamate as a neurotransmitter/neuromodulator in the gastrointestinal tract. Such effort has provided immunohistochemical, biomolecular and functional data suggesting that the entire glutamatergic neurotransmitter machinery is present in the complex circuitries of the enteric nervous system (ENS), which participates to the local coordination of gastrointestinal functions. Glutamate is also involved in the regulation of the brain-gut axis, a bi-directional connection pathway between the central nervous system (CNS) and the gut. The neurotransmitter contributes to convey information, via afferent fibers, from the gut to the brain, and to send appropriate signals, via efferent fibers, from the brain to control gut secretion and motility. In analogy with the CNS, an increasing number of studies suggest that dysregulation of the enteric glutamatergic neurotransmitter machinery may lead to gastrointestinal dysfunctions. On the whole, this research field has opened the possibility to find new potential targets for development of drugs for the treatment of gastrointestinal diseases. The present review analyzes the more recent literature on enteric glutamatergic neurotransmission both in physiological and pathological conditions, such as gastroesophageal reflux, gastric acid hypersecretory diseases, inflammatory bowel disease, irritable bowel syndrome and intestinal ischemia/reperfusion injury.
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Affiliation(s)
- Viviana Filpa
- Department of Clinical and Experimental Medicine, University of Insubria, via H. Dunant 5, I-21100 Varese, Italy
| | - Elisabetta Moro
- Department of Internal Medicine and Therapeutics, Section of Pharmacology, via Ferrata 9, I-27100 Pavia, Italy
| | - Marina Protasoni
- Department of Surgical and Morphological Sciences, University of Insubria, via F. Guicciardini 9, I-21100 Varese, Italy
| | - Francesca Crema
- Department of Internal Medicine and Therapeutics, Section of Pharmacology, via Ferrata 9, I-27100 Pavia, Italy
| | - Gianmario Frigo
- Department of Internal Medicine and Therapeutics, Section of Pharmacology, via Ferrata 9, I-27100 Pavia, Italy
| | - Cristina Giaroni
- Department of Clinical and Experimental Medicine, University of Insubria, via H. Dunant 5, I-21100 Varese, Italy
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Balasuriya GK, Hill-Yardin EL, Gershon MD, Bornstein JC. A sexually dimorphic effect of cholera toxin: rapid changes in colonic motility mediated via a 5-HT3 receptor-dependent pathway in female C57Bl/6 mice. J Physiol 2016; 594:4325-38. [PMID: 26990461 DOI: 10.1113/jp272071] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Accepted: 03/11/2016] [Indexed: 12/19/2022] Open
Abstract
KEY POINTS Cholera causes more than 100,000 deaths each year as a result of severe diarrhoea, vomiting and dehydration due to the actions of cholera toxin; more females than males are affected. Cholera toxin induces hypersecretion via release of mucosal serotonin and over-activation of enteric neurons, but its effects on gastrointestinal motility are not well characterized. We found that cholera toxin rapidly and reversibly reduces colonic motility in female mice in oestrus, but not in males or females in prooestrus, an effect mediated by 5-HT in the colonic mucosa and by 5-HT3 receptors. We show that the number of mucosal enterochromaffin cells containing 5-HT changes with the oestrous cycle in mice. These findings indicate that cholera toxin's effects on motility are rapid and depend on the oestrous cycle and therefore can help us better understand differences in responses in males and female patients. ABSTRACT Extensive studies of the mechanisms responsible for the hypersecretion produced by cholera toxin (CT) have shown that this toxin produces a massive over-activation of enteric neural secretomotor circuits. The effects of CT on gastrointestinal motility, however, have not been adequately characterized. We investigated effects of luminal CT on neurally mediated motor activity in ex vivo male and female mouse full length colon preparations. We used video recording and spatiotemporal maps of contractile activity to quantify colonic migrating motor complexes (CMMCs) and resting colonic diameter. We compared effects of CT in female colon from wild-type and mice lacking tryptophan hydroxylase (TPH1KO). We also compared CMMCs in colons of female mice in oestrus with those in prooestrus. In female (but not male) colon, CT rapidly, reversibly and concentration-dependently inhibits CMMC frequency and induces a tonic constriction. These effects were blocked by granisetron (5-HT3 antagonist) and were absent from TPH1KO females. CT effects were prominent at oestrus but absent at prooestrus. The number of EC cells containing immunohistochemically demonstrable serotonin (5-HT) was 30% greater in female mice during oestrus than during prooestrus or in males. We conclude that CT inhibits CMMCs via release of mucosal 5-HT, which activates an inhibitory pathway involving 5-HT3 receptors. This effect is sex- and oestrous cycle-dependent and is probably due to an oestrous cycle-dependent change in the number of 5-HT-containing EC cells in the colonic mucosa.
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Affiliation(s)
| | - Elisa L Hill-Yardin
- Department of Physiology, University of Melbourne, Parkville Vic, 3010, Australia
| | - Michael D Gershon
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, NY, 10032, USA
| | - Joel C Bornstein
- Department of Physiology, University of Melbourne, Parkville Vic, 3010, Australia
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Krueger D, Michel K, Zeller F, Demir IE, Ceyhan GO, Slotta-Huspenina J, Schemann M. Neural influences on human intestinal epithelium in vitro. J Physiol 2015; 594:357-72. [PMID: 26527433 DOI: 10.1113/jp271493] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 10/20/2015] [Indexed: 12/12/2022] Open
Abstract
KEY POINTS We present the first systematic and, up to now, most comprehensive evaluation of the basic features of epithelial functions, such as basal and nerve-evoked secretion, as well as tissue resistance, in over 2200 surgical specimens of human small and large intestine. We found no evidence for impaired nerve-evoked epithelial secretion or tissue resistance with age or disease pathologies (stomach, pancreas or colon cancer, polyps, diverticulitis, stoma reversal). This indicates the validity of future studies on epithelial secretion or resistance that are based on data from a variety of surgical specimens. ACh mainly mediated nerve-evoked and basal secretion in the small intestine, whereas vasoactive intestinal peptide and nitric oxide were the primary pro-secretory transmitters in the large intestine. The results of the present study revealed novel insights into regional differences in nerve-mediated secretion in the human intestine and comprise the basis by which to more specifically target impaired epithelial functions in the diseased gut. ABSTRACT Knowledge on basic features of epithelial functions in the human intestine is scarce. We used Ussing chamber techniques to record basal tissue resistance (R-basal) and short circuit currents (ISC; secretion) under basal conditions (ISC-basal) and after electrical field stimulation (ISC-EFS) of nerves in 2221 resectates from 435 patients. ISC-EFS was TTX-sensitive and of comparable magnitude in the small and large intestine. ISC-EFS or R-basal were not influenced by the patients' age, sex or disease pathologies (cancer, polyps, diverticulitis). Ion substitution, bumetanide or adenylate cyclase inhibition studies suggested that ISC-EFS depended on epithelial cAMP-driven chloride and bicarbonate secretion but not on amiloride-sensitive sodium absorption. Although atropine-sensitive cholinergic components prevailed for ISC-EFS of the duodenum, jejunum and ileum, PG97-269-sensitive [vasoactive intestinal peptide (VIP) receptor 1 antagonist] VIPergic together with L-NAME-sensitive nitrergic components dominated the ISC-EFS in colonic preparations. Differences in numbers of cholinergic or VIPergic neurons, sensitivity of epithelial muscarinic or VIP receptors, or stimulus frequency-dependent transmitter release were not responsible for the region-specific transmitter contribution to ISC-EFS. Instead, the low atropine-sensitivity of ISC-EFS in the colon was the result of high cholinesterase activity because neostigmine revealed cholinergic components. Colonic ISC-EFS remained unchanged after tachykinin, P2X, P2Y or A1 and A2 receptor blockade. R-basal was smaller and ISC-basal was higher in the small intestine. TTX and bumetanide decreased ISC-basal in all regions, suggesting nerve-dependent secretory tone. ISC-basal was atropine-sensitive in the small intestine and PG97-269-sensitive in the large intestine. This comprehensive study reveals novel insights into region-specific nerve-mediated secretion in the human small and large intestine.
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Affiliation(s)
- Dagmar Krueger
- Human Biology, Technische Universität München, Freising, Germany
| | - Klaus Michel
- Human Biology, Technische Universität München, Freising, Germany
| | | | - Ihsan E Demir
- Department of General Surgery, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany
| | - Güralp O Ceyhan
- Department of General Surgery, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany
| | - Julia Slotta-Huspenina
- Institute of Pathology, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany
| | - Michael Schemann
- Human Biology, Technische Universität München, Freising, Germany
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18
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Lucas ML, Morrison JD. An investigation into the relationship between small intestinal fluid secretion and systemic arterial blood pressure in the anesthetized rat. Physiol Rep 2015; 3:3/5/e12407. [PMID: 26019291 PMCID: PMC4463835 DOI: 10.14814/phy2.12407] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The effects of changes in the steady level of diastolic blood pressure on fluid flux across the jejunum has been investigated in the anesthetized rat during perfusion with a nutrient-free and Na+-free solution. Diastolic blood pressure was manipulated by intravenous infusions, during the jejunal perfusions, of vasodilators (vasoactive intestinal polypeptide, acetyl-β-methylcholine, and phentolamine) and a vasoconstrictor (arginine vasopressin), each of which acts through a different cellular mechanism. The outcome was that fluid flux was related by a parabolic relationship with diastolic blood pressure in which net secretion occurred over the range 40–100 mmHg, whereas net absorption was recorded at diastolic pressures exceeding 100 mmHg and below 40 mmHg. Against a background of normal absorption promoted by perfusion with 145 mmol L−1 Na+/5 mmol L−1 glucose solution, reductions in diastolic blood pressure markedly reduced the mean rate of fluid absorption by 58% overall, whereas the rate of glucose absorption remained unchanged. Our results were explained on the basis that vasodilatation led to increased capillary pressure and then to net filtration of fluid from the mesenteric capillary bed. Experiments in which Escherichia coli heat-stable toxin was added to the jejunal perfusate confirmed the absence of a secretory response, which was consistent with the absence of effect of the toxin on diastolic blood pressure.
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Affiliation(s)
- Michael L Lucas
- School of Life Sciences, University of Glasgow, West Medical Building, Glasgow, G12 8QQ, U.K
| | - James D Morrison
- School of Life Sciences, University of Glasgow, West Medical Building, Glasgow, G12 8QQ, U.K
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19
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Vather R, O'Grady G, Bissett IP, Dinning PG. Postoperative ileus: mechanisms and future directions for research. Clin Exp Pharmacol Physiol 2014; 41:358-70. [PMID: 24754527 DOI: 10.1111/1440-1681.12220] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 02/13/2014] [Accepted: 02/25/2014] [Indexed: 12/13/2022]
Abstract
Postoperative ileus (POI) is an abnormal pattern of gastrointestinal motility characterized by nausea, vomiting, abdominal distension and/or delayed passage of flatus or stool, which may occur following surgery. Postoperative ileus slows recovery, increases the risk of developing postoperative complications and confers a significant financial load on healthcare institutions. The aim of the present review is to provide a succinct overview of the clinical features and pathophysiological mechanisms of POI, with final comment on selected directions for future research.Terminology used when describing POI is inconsistent, with little differentiation made between the obligatory period of gut dysfunction seen after surgery ('normal POI') and the more clinically and pathologically significant entity of a 'prolonged POI'. Both normal and prolonged POI represent a fundamentally similar pathophysiological phenomenon. The aetiology of POI is postulated to be multifactorial, with principal mediators being inflammatory cell activation, autonomic dysfunction (both primarily and as part of the surgical stress response), agonism at gut opioid receptors, modulation of gastrointestinal hormone activity and electrolyte derangements. A final common pathway for these effectors is impaired contractility and motility and gut wall oedema. There are many potential directions for future research. In particular, there remains scope to accurately characterize the gastrointestinal dysfunction that underscores an ileus, development of an accurate risk stratification tool will facilitate early implementation of preventive measures and clinical appraisal of novel therapeutic strategies that target individual pathways in the pathogenesis of ileus warrant further investigation.
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Affiliation(s)
- Ryash Vather
- Department of Surgery, University of Auckland, Auckland, New Zealand
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20
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The enteric nervous system and gastrointestinal innervation: integrated local and central control. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 817:39-71. [PMID: 24997029 DOI: 10.1007/978-1-4939-0897-4_3] [Citation(s) in RCA: 492] [Impact Index Per Article: 49.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The digestive system is innervated through its connections with the central nervous system (CNS) and by the enteric nervous system (ENS) within the wall of the gastrointestinal tract. The ENS works in concert with CNS reflex and command centers and with neural pathways that pass through sympathetic ganglia to control digestive function. There is bidirectional information flow between the ENS and CNS and between the ENS and sympathetic prevertebral ganglia.The ENS in human contains 200-600 million neurons, distributed in many thousands of small ganglia, the great majority of which are found in two plexuses, the myenteric and submucosal plexuses. The myenteric plexus forms a continuous network that extends from the upper esophagus to the internal anal sphincter. Submucosal ganglia and connecting fiber bundles form plexuses in the small and large intestines, but not in the stomach and esophagus. The connections between the ENS and CNS are carried by the vagus and pelvic nerves and sympathetic pathways. Neurons also project from the ENS to prevertebral ganglia, the gallbladder, pancreas and trachea.The relative roles of the ENS and CNS differ considerably along the digestive tract. Movements of the striated muscle esophagus are determined by neural pattern generators in the CNS. Likewise the CNS has a major role in monitoring the state of the stomach and, in turn, controlling its contractile activity and acid secretion, through vago-vagal reflexes. In contrast, the ENS in the small intestine and colon contains full reflex circuits, including sensory neurons, interneurons and several classes of motor neuron, through which muscle activity, transmucosal fluid fluxes, local blood flow and other functions are controlled. The CNS has control of defecation, via the defecation centers in the lumbosacral spinal cord. The importance of the ENS is emphasized by the life-threatening effects of some ENS neuropathies. By contrast, removal of vagal or sympathetic connections with the gastrointestinal tract has minor effects on GI function. Voluntary control of defecation is exerted through pelvic connections, but cutting these connections is not life-threatening and other functions are little affected.
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21
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Vather R, O'Grady G, Bissett IP, Dinning PG. Postoperative ileus: mechanisms and future directions for research. Clin Exp Pharmacol Physiol 2014. [DOI: 10.1111/1440-1681.12220 10.1016/j.ijge.2013.08.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Ryash Vather
- Department of Surgery; University of Auckland; Auckland New Zealand
| | - Greg O'Grady
- Department of Surgery; University of Auckland; Auckland New Zealand
| | - Ian P Bissett
- Department of Surgery; University of Auckland; Auckland New Zealand
| | - Phil G Dinning
- Departments of Gastroenterology and Surgery; Flinders Medical Centre; Flinders University; Adelaide SA Australia
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22
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Fung C, Unterweger P, Parry LJ, Bornstein JC, Foong JPP. VPAC1 receptors regulate intestinal secretion and muscle contractility by activating cholinergic neurons in guinea pig jejunum. Am J Physiol Gastrointest Liver Physiol 2014; 306:G748-58. [PMID: 24578344 DOI: 10.1152/ajpgi.00416.2013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In the gastrointestinal tract, vasoactive intestinal peptide (VIP) is found exclusively within neurons. VIP regulates intestinal motility via neurally mediated and direct actions on smooth muscle and secretion by a direct mucosal action, and via actions on submucosal neurons. VIP acts via VPAC1 and VPAC2 receptors; however, the subtype involved in its neural actions is unclear. The neural roles of VIP and VPAC1 receptors (VPAC1R) were investigated in intestinal motility and secretion in guinea pig jejunum. Expression of VIP receptors across the jejunal layers was examined using RT-PCR. Submucosal and myenteric neurons expressing VIP receptor subtype VPAC1 and/or various neurochemical markers were identified immunohistochemically. Isotonic muscle contraction was measured in longitudinal muscle-myenteric plexus preparations. Electrogenic secretion across mucosa-submucosa preparations was measured in Ussing chambers by monitoring short-circuit current. Calretinin(+) excitatory longitudinal muscle motor neurons expressed VPAC1R. Most cholinergic submucosal neurons, notably NPY(+) secretomotor neurons, expressed VPAC1R. VIP (100 nM) induced longitudinal muscle contraction that was inhibited by TTX (1 μM), PG97-269 (VPAC1 antagonist; 1 μM), and hyoscine (10 μM), but not by hexamethonium (200 μM). VIP (50 nM)-evoked secretion was depressed by hyoscine or PG97-269 and involved a small TTX-sensitive component. PG97-269 and TTX combined did not further depress the VIP response observed in the presence of PG97-269 alone. We conclude that VIP stimulates ACh-mediated longitudinal muscle contraction via VPAC1R on cholinergic motor neurons. VIP induces Cl(-) secretion directly via epithelial VPAC1R and indirectly via VPAC1R on cholinergic secretomotor neurons. No evidence was obtained for involvement of other neural VIP receptors.
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Affiliation(s)
- Candice Fung
- Department of Physiology, University of Melbourne, Parkville, Victoria, Australia; and
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23
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Vu JP, Million M, Larauche M, Luong L, Norris J, Waschek JA, Pothoulakis C, Pisegna JR, Germano PM. Inhibition of vasoactive intestinal polypeptide (VIP) induces resistance to dextran sodium sulfate (DSS)-induced colitis in mice. J Mol Neurosci 2014; 52:37-47. [PMID: 24395090 DOI: 10.1007/s12031-013-0205-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 12/04/2013] [Indexed: 12/31/2022]
Abstract
VIP is highly expressed in the colon and regulates motility, vasodilatation, and sphincter relaxation. However, its role in the development and progress of colitis is still controversial. Our aim was to determine the participation of VIP on dextran sodium sulfate (DSS)-induced colonic mucosal inflammation using VIP(-/-) and WT mice treated with VIP antagonists. Colitis was induced in 32 adult VIP(-/-) and 14 age-matched WT litter-mates by giving 2.5 % DSS in the drinking water. DSS-treated WT mice were injected daily with VIP antagonists, VIPHyb (n = 22), PG 97-269 (n = 9), or vehicle (n = 31). After euthanasia, colons were examined; colonic cytokines mRNA were quantified. VIP(-/-) mice were remarkably resistant to DSS-induced colitis compared to WT. Similarly, DSS-treated WT mice injected with VIPHyb (1 μM) or PG 97-269 (1 nM) had significantly reduced clinical signs of colitis. Furthermore, colonic expression of IL-1ϐ, TNF-α, and IL-6 was significantly lower in VIP(-/-) and VIPHyb or PG 97-269 compared to vehicle-treated WT. Genetic deletion of VIP or pharmacological inhibition of VIP receptors resulted in resistance to colitis. These data demonstrate a pro-inflammatory role for VIP in murine colitis and suggest that VIP antagonists may be an effective clinical treatment for human inflammatory bowel diseases.
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Affiliation(s)
- John P Vu
- CURE/Digestive Diseases Research Center, Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles and VA Greater Los Angeles Health Care System, Los Angeles, CA, USA
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Chandrasekharan B, Nezami BG, Srinivasan S. Emerging neuropeptide targets in inflammation: NPY and VIP. Am J Physiol Gastrointest Liver Physiol 2013; 304:G949-57. [PMID: 23538492 PMCID: PMC3680683 DOI: 10.1152/ajpgi.00493.2012] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The enteric nervous system (ENS), referred to as the "second brain," comprises a vast number of neurons that form an elegant network throughout the gastrointestinal tract. Neuropeptides produced by the ENS play a crucial role in the regulation of inflammatory processes via cross talk with the enteric immune system. In addition, neuropeptides have paracrine effects on epithelial secretion, thus regulating epithelial barrier functions and thereby susceptibility to inflammation. Ultimately the inflammatory response damages the enteric neurons themselves, resulting in deregulations in circuitry and gut motility. In this review, we have emphasized the concept of neurogenic inflammation and the interaction between the enteric immune system and enteric nervous system, focusing on neuropeptide Y (NPY) and vasoactive intestinal peptide (VIP). The alterations in the expression of NPY and VIP in inflammation and their significant roles in immunomodulation are discussed. We highlight the mechanism of action of these neuropeptides on immune cells, focusing on the key receptors as well as the intracellular signaling pathways that are activated to regulate the release of cytokines. In addition, we also examine the direct and indirect mechanisms of neuropeptide regulation of epithelial tight junctions and permeability, which are a crucial determinant of susceptibility to inflammation. Finally, we also discuss the potential of emerging neuropeptide-based therapies that utilize peptide agonists, antagonists, siRNA, oligonucleotides, and lentiviral vectors.
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Affiliation(s)
- Bindu Chandrasekharan
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA.
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Sant'Ana DMG, Góis MB, Zanoni JN, da Silva AV, da Silva CJT, Araújo EJA. Intraepithelial lymphocytes, goblet cells and VIP-IR submucosal neurons of jejunum rats infected with Toxoplasma gondii. Int J Exp Pathol 2012; 93:279-86. [PMID: 22804764 DOI: 10.1111/j.1365-2613.2012.00824.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Toxoplasma gondii (T. gondii) crosses the intestinal barrier in oral infections and can lead to changes in different cell types, including the neurons located there. In the gastrointestinal system, the autonomous nervous system component that regulate blood flow and mucous secretion is the submucosal plexus. The aim of this study was to examine the effects of T. gondii infection on intraepithelial lymphocytes (IELs), goblet cells and submucosal neurons that are immunoreactive to vasoactive intestinal peptide (VIP-IR) of rat jejunum. Twenty male rats distributed as a control group (CG) and an infected group (IG), which received a suspension with 500 parasite oocysts (strain ME-49, genotype II) orally, were assessed. Routine histological sections were used to quantify IELs and to detect mucins secreted by goblet cells. Whole mounts including the submucosal layer were examined using immunofluorescence to detect the VIP neurotransmitter. Quantitative alterations in IELs were not observed. However, the reduction (P < 0.05) in the number of goblet cells that produce neutral mucins (PAS+) and sulphomucins (AB pH 1.0) and the maintenance of sialomucin-secreting cells (AB pH 2.5) resulting in a more fluid mucous were observed. Concerning the VIP-IR submucosal neurons, an increase in fluorescence on IG animals was observed. There was a reduction (P < 0.05) in the number of VIP-IR submucosal neurons and atrophy of their cell bodies in IG rats. Infection with T. gondii caused alterations in the chemical composition of the intestinal mucous and reduction in the neuron number and atrophy of the remaining neurons in this cell subpopulation.
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Abstract
Neurogastroenterology is defined as neurology of the gastrointestinal tract, liver, gallbladder and pancreas and encompasses control of digestion through the enteric nervous system (ENS), the central nervous system (CNS) and integrative centers in sympathetic ganglia. This Review provides a broad overview of the field of neurogastroenterology, with a focus on the roles of the ENS in the control of the musculature of the gastrointestinal tract and transmucosal fluid movement. Digestion is controlled through the integration of multiple signals from the ENS and CNS; neural signals also pass between distinct gut regions to coordinate digestive activity. Moreover, neural and endocrine control of digestion is closely coordinated. Interestingly, the extent to which the ENS or CNS controls digestion differs considerably along the digestive tract. The importance of the ENS is emphasized by the life-threatening effects of certain ENS neuropathies, including Hirschsprung disease and Chagas disease. Other ENS disorders, such as esophageal achalasia and gastroparesis, cause varying degrees of dysfunction. The neurons in enteric reflex pathways use a wide range of chemical messengers that signal through an even wider range of receptors. These receptors provide many actual and potential targets for modifying digestive function.
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Affiliation(s)
- John B Furness
- Department of Anatomy and Neuroscience, University of Melbourne, Grattan Street, Parkville, VIC 3010, Australia.
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Enteroendocrine and neuronal mechanisms in pathophysiology of acute infectious diarrhea. Dig Dis Sci 2012; 57:19-27. [PMID: 22001941 PMCID: PMC3809758 DOI: 10.1007/s10620-011-1939-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 09/30/2011] [Indexed: 12/30/2022]
Abstract
BACKGROUND While enterocyte secretion is the predominant mechanism considered responsible for secretory diarrhea in response to acute enteric infections, there are several lines of evidence that support alternative mechanisms controlling fluid and electrolyte secretion in diarrhea. AIM To review enteroendocrine and neuronal mechanisms that participate in the development of acute infectious diarrhea. RECENT ADVANCES Acute infectious diarrheas due to bacterial toxins (e.g., cholera, E. coli heat-stable enterotoxin, C. difficile) and rotavirus are all associated with secretion of transmitters from enteroendocrine cells (e.g., 5-HT) and activation of afferent neurons that stimulate submucosal secretomotor neurons. The latter secrete acetylcholine (which binds to muscarinic receptors on epithelial cells) and VIP. Involvement of nerves was demonstrated by inhibition of bacterial toxin-induced secretion by hexamethonium (nicotinic), tetrodotoxin (Na(+) channel blocker), and lidocaine (visceral/mucosal afferents). Nicotinic receptors are present on secretomotoneurons and these are activated by release of acetylcholine from enteric interneurons or extrinsic efferent fibers. Specific organisms also modify other mechanisms that may contribute to development of acute diarrhea. Thus, mucin secretion, activation of motor mechanisms, increased mucosal permeability and inhibition of bile acid absorption have been reported in specific types of acute infectious diarrhea. CONCLUSION New therapies targeting neural and transmitter mediation including 5-HT, VIP, NPY, as well as toxin receptors and channels activated during acute infectious diarrhea could usher in a novel approach to enhancing glucose-electrolyte solutions used in the treatment of acute diarrhea.
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Lundgren O, Jodal M, Jansson M, Ryberg AT, Svensson L. Intestinal epithelial stem/progenitor cells are controlled by mucosal afferent nerves. PLoS One 2011; 6:e16295. [PMID: 21347406 PMCID: PMC3036584 DOI: 10.1371/journal.pone.0016295] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Accepted: 12/22/2010] [Indexed: 01/07/2023] Open
Abstract
Background The maintenance of the intestinal epithelium is of great importance for the survival of the organism. A possible nervous control of epithelial cell renewal was studied in rats and mice. Methods Mucosal afferent nerves were stimulated by exposing the intestinal mucosa to capsaicin (1.6 mM), which stimulates intestinal external axons. Epithelial cell renewal was investigated in the jejunum by measuring intestinal thymidine kinase (TK) activity, intestinal 3H-thymidine incorporation into DNA, and the number of crypt cells labeled with BrdU. The influence of the external gut innervation was minimized by severing the periarterial nerves. Principal Findings Luminal capsaicin increased all the studied variables, an effect nervously mediated to judge from inhibitory effects on TK activity or 3H-thymidine incorporation into DNA by exposing the mucosa to lidocaine (a local anesthetic) or by giving four different neurotransmitter receptor antagonists i.v. (muscarinic, nicotinic, neurokinin1 (NK1) or calcitonin gene related peptide (CGRP) receptors). After degeneration of the intestinal external nerves capsaicin did not increase TK activity, suggesting the involvement of an axon reflex. Intra-arterial infusion of Substance P (SP) or CGRP increased intestinal TK activity, a response abolished by muscarinic receptor blockade. Immunohistochemistry suggested presence of M3 and M5 muscarinic receptors on the intestinal stem/progenitor cells. We propose that the stem/progenitor cells are controlled by cholinergic nerves, which, in turn, are influenced by mucosal afferent neuron(s) releasing acetylcholine and/or SP and/or CGRP. In mice lacking the capsaicin receptor, thymidine incorporation into DNA and number of crypt cells labeled with BrdU was lower than in wild type animals suggesting that nerves are important also in the absence of luminal capsaicin, a conclusion also supported by the observation that atropine lowered thymidine incorporation into DNA by 60% in control rat segments. Conclusion Enteric nerves are of importance in maintaining the intestinal epithelial barrier.
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Affiliation(s)
- Ove Lundgren
- Section of Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden.
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Abstract
According to the World Health Organization, there are approximately 2 billion annual cases of diarrhea worldwide. Diarrhea is the leading cause of death in children younger than 5 years and kills 1.5 million children each year. It is especially prevalent in the developing world, where mortality is related to dehydration, electrolyte disturbance, and the resultant acidosis, and in 2001, it accounted for 1.78 million deaths (3.7% of total deaths) in low- and middle-income countries. However, diarrhea is also a common problem in the developed world, with 211 million to 375 million episodes of infectious diarrheal illnesses in the United States annually, resulting in 73 million physician consultations, 1.8 million hospitalizations, and 3100 deaths. Furthermore, 4% to 5% of the Western population suffers from chronic diarrhea. Given the high prevalence of diarrhea, research has been directed at learning more about the cellular mechanisms underlying diarrheal illnesses in order to develop new medications directed at novel cellular targets. These cellular mechanisms and targets are discussed in this article.
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Affiliation(s)
- Alexandra J Kent
- Department of Gastroenterology, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK
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Foong JPP, Bornstein JC. mGluR(1) Receptors Contribute to Non-Purinergic Slow Excitatory Transmission to Submucosal VIP Neurons of Guinea-Pig Ileum. Front Neurosci 2009; 3:46. [PMID: 20582273 PMCID: PMC2695390 DOI: 10.3389/neuro.21.001.2009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Accepted: 05/14/2009] [Indexed: 11/23/2022] Open
Abstract
Vasoactive intestinal peptide (VIP) immunoreactive secretomotor neurons in the submucous plexus are involved in mediating bacterial toxin-induced hypersecretion leading to diarrhoea. VIP neurons become hyperexcitable after the mucosa is exposed to cholera toxin, which suggests that the manipulation of the excitability of these neurons may be therapeutic. This study used standard intracellular recording methods to systematically characterize slow excitatory postsynaptic potentials (EPSPs) evoked in submucosal VIP neurons by different stimulus regimes (1, 3 and 15 pulse 30 Hz stimulation), together with their associated input resistances and pharmacology. All slow EPSPs were associated with a significant increase in input resistance compared to baseline values. Slow EPSPs evoked by a single stimulus were confirmed to be purinergic, however, slow EPSPs evoked by 15 pulse trains were non-purinergic and those evoked by 3 pulse trains were mixed. NK1 or NK3 receptor antagonists did not affect slow EPSPs. The group I mGluR receptor antagonist, PHCCC reduced the amplitude of purinergic and non-purinergic slow EPSPs. Blocking mGluR1 receptors depressed the overall response to 3 and 15 pulse trains, but this effect was inconsistent, while blockade of mGluR5 receptors had no effect on the non-purinergic slow EPSPs. Thus, although other receptors are almost certainly involved, our data indicate that there are at least two pharmacologically distinct types of slow EPSPs in the VIP secretomotor neurons: one mediated by P2Y receptors and the other in part by mGluR1 receptors.
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Identification of neuron types in the submucosal ganglia of the mouse ileum. Cell Tissue Res 2009; 336:179-89. [PMID: 19326148 DOI: 10.1007/s00441-009-0773-2] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Accepted: 01/28/2009] [Indexed: 12/20/2022]
Abstract
The continuing and even expanding use of genetically modified mice to investigate the normal physiology and development of the enteric nervous system and for the study of pathophysiology in mouse models emphasises the need to identify all the neuron types and their functional roles in mice. An investigation that chemically and morphologically defined all the major neuron types with cell bodies in myenteric ganglia of the mouse small intestine was recently completed. The present study was aimed at the submucosal ganglia, with the purpose of similarly identifying the major neuron types with cell bodies in these ganglia. We found that the submucosal neurons could be divided into three major groups: neurons with vasoactive intestinal peptide (VIP) immunoreactivity (51% of neurons), neurons with choline acetyltransferase (ChAT) immunoreactivity (41% of neurons) and neurons that expressed neither of these markers. Most VIP neurons contained neuropeptide Y (NPY) and about 40% were immunoreactive for tyrosine hydroxylase (TH); 22% of all submucosal neurons were TH/VIP. VIP-immunoreactive nerve terminals in the mucosa were weakly immunoreactive for TH but separate populations of TH- and VIP-immunoreactive axons innervated the arterioles in the submucosa. Of the ChAT neurons, about half were immunoreactive for both somatostatin and calcitonin gene-related peptide (CGRP). Calretinin immunoreactivity occurred in over 90% of neurons, including the VIP neurons. The submucosal ganglia and submucosal arterioles were innervated by sympathetic noradrenergic neurons that were immunoreactive for TH and NPY; no VIP and few calretinin fibres innervated submucosal neurons. We conclude that the submucosal ganglia contain cell bodies of VIP/NPY/TH/calretinin non-cholinergic secretomotor neurons, VIP/NPY/calretinin vasodilator neurons, ChAT/CGRP/somatostatin/calretinin cholinergic secretomotor neurons and small populations of cholinergic and non-cholinergic neurons whose targets have yet to be identified. No evidence for the presence of type-II putative intrinsic primary afferent neurons was found.
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Gwynne RM, Ellis M, Sjövall H, Bornstein JC. Cholera toxin induces sustained hyperexcitability in submucosal secretomotor neurons in guinea pig jejunum. Gastroenterology 2009; 136:299-308.e4. [PMID: 19026646 DOI: 10.1053/j.gastro.2008.09.071] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Revised: 09/16/2008] [Accepted: 09/25/2008] [Indexed: 02/01/2023]
Abstract
BACKGROUND & AIMS Neural mechanisms underlying cholera toxin (CT)-induced intestinal hypersecretion remain unclear. We investigated long-term excitability changes in vasoactive intestinal peptide (VIP) and neuropeptide Y (NPY) secretomotor neurons after prolonged luminal exposure to CT. METHODS Isolated segments of guinea pig jejunum were incubated with saline or CT +/- neurotransmitter antagonist in the lumen; the submucosal plexus was then dissected clear, circumferentially adjacent to intact mucosa. Synaptic inputs and firing properties of S neurons in ganglia next to the mucosa in control saline were studied using intracellular recording. Neurons were processed for VIP and NPY immunoreactivity. RESULTS Thirty S neurons (20 VIP(+), 7 NPY(+), 3 VIP(-)/NPY(-)) from CT-treated preparations and 27 control S neurons (19 VIP(+), 4 NPY(+), 4 VIP(-)/NPY(-)) in ganglia adjacent to intact mucosa were analyzed. VIP(+) and NPY(+) neurons in CT-treated preparations fired significantly more action potentials and for longer periods during injected depolarizing current pulses (50-350 pA) than control neurons. Addition of tetrodotoxin, hexamethonium, granisetron, or the neurokinin-1 (NK1) antagonist SR140333 during the CT incubation blocked CT-induced effects in both neuron types. The NK3 antagonist SR142801 blocked CT-induced effects in NPY(+) neurons and reduced the number of action potentials in VIP(+) neurons. Synaptic activity was unaffected by CT. CONCLUSIONS CT induces specific and sustained hyperexcitability of secretomotor neurons in enteric pathways. CT acts in the mucosa. Its effect is neurally mediated and depends on 5-hydroxytryptamine-3, nicotinic, and NK1 receptors. This system represents a unique model to understand the neural mechanisms of action of CT and to identify therapeutic targets.
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Affiliation(s)
- Rachel M Gwynne
- Department of Physiology, University of Melbourne, Parkville, Victoria, Australia.
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van Haver ER, de Vooght L, Oste M, Sangild PT, Thymann T, Weyns ALM, van Ginneken CJ. Postnatal and diet-dependent increases in enteric glial cells and VIP-containing neurones in preterm pigs. Neurogastroenterol Motil 2008; 20:1070-9. [PMID: 18643892 DOI: 10.1111/j.1365-2982.2008.01160.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A mature enteric nervous system (ENS) is required to ensure a normal pattern of intestinal motility in order to regulate digestion after birth. We hypothesized that neuronal and glial components of the ENS would mature during the first postnatal days in preterm pigs that are a sensitive animal model of food intolerance and necrotizing enterocolitis (NEC). Stereological volume densities of the general neuronal population [assessed by betaIII-tubulin immunoreactivity (IR)] and subsets of neuronal (VIP-IR and nitrergic IR) and glial cells (GFAP-IR and S100-IR) were determined in the small intestine of newborn preterm piglets (93% gestation), after 3 days of receiving total parenteral nutrition (TPN) and after 3 days of TPN plus 2 days of enteral feeding with sow's colostrum or milk formula. Following TPN, VIP in the myenteric and inner submucous plexus and GFAP in the inner submucous plexus increased, while the relative volume of the total neuronal population remained constant. Introduction of enteral food induced variable degrees of food intolerance and NEC, especially after formula feeding, a diet that gave rise to a higher myenteric VIP and GFAP content in the inner submucous plexus than colostrum feeding. However, the ENS seemed unaffected by the presence of NEC-like intestinal lesions. Nevertheless, this study shows that the ENS is highly plastic during the first days after premature birth and adapts in an age- and diet-dependent manner. The observed postnatal adaptation in enteric VIP and GFAP may help to maintain intestinal homeostasis during suboptimal feeding regimens in preterm neonates.
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Affiliation(s)
- E R van Haver
- Department of Veterinary Medicine, University of Antwerp, Wilrijk, Belgium
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Burleigh DE, Banks MR. Stimulation of intestinal secretion by vasoactive intestinal peptide and cholera toxin. Auton Neurosci 2007; 133:64-75. [PMID: 17023221 DOI: 10.1016/j.autneu.2006.08.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Accepted: 08/01/2006] [Indexed: 10/24/2022]
Affiliation(s)
- David E Burleigh
- Department of Adult and Paediatric Gastroenterology, The Wingate Institute, St. Bartholomew's and The Royal London School of Medicine and Dentistry, London E1 2AJ, United Kingdom.
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Talero E, Sánchez-Fidalgo S, Ramón Calvo J, Motilva V. Galanin in the trinitrobenzene sulfonic acid rat model of experimental colitis. Int Immunopharmacol 2006; 6:1404-12. [PMID: 16846834 DOI: 10.1016/j.intimp.2006.04.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 03/03/2006] [Accepted: 04/07/2006] [Indexed: 01/10/2023]
Abstract
Neuropeptides are molecules produced by a variety of cells that modulate several biological processes and modify the activity of cells responsible either to trigger tissue damage and to promote healing in the intestine. Galanin is a neuropeptide present in enteric nerves lining the gastrointestinal tract and involved in the secretion and contractility regulation. The aim of this study is to investigate its potential therapeutic experimental use in an immunological disorder, such as experimental trinitrobenzensulfonic acid (TNBS)-induced colitis in rats. Galanin (10, 20 and 40 microg/kg/day) was administered by intraperitoneal route 48, 24 and 1 h prior to the induction of colitis and 24 h later, and the animals were sacrificed 48 h after. The lesions were blindly scored according to macroscopic and histological scales. The inflammatory response was assessed by histological analysis and by myeloperoxidase activity (MPO) and tumour necrosis factor-alpha (TNF-alpha) production. The results indicated that Galanin prevented the morphological alteration and reduced ulcer index associated with TNBS. In addition, Galanin reduced MPO and TNF-alpha values significantly. In order to elucidate some of the mechanisms, cycloxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression was analyzed by Western blotting. COX-2 was not modified, but iNOS protein was significantly reduced accompanied by a diminished nitrite production, in a dose-dependent manner, in comparison to the TNBS group. In conclusion, Galanin treatment has a significant preventive effect in the TNBS-induced acute model of colitis with reduction of the analyzed inflammatory parameters. Moreover, the results obtained demonstrated by the first time that Galanin administration promotes an important reduction in NO-related mechanisms.
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Affiliation(s)
- Elena Talero
- Department of Pharmacology, School of Pharmacy, University of Seville, Seville, Spain
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Kordasti S, Sapnara M, Thomas EA, Lindstrom E, Forsman M, Bornstein JC, Sjövall H. Effects of cholera toxin on the potential difference and motor responses induced by distension in the rat proximal small intestine in vivo. Am J Physiol Gastrointest Liver Physiol 2006; 290:G948-58. [PMID: 16357061 DOI: 10.1152/ajpgi.00267.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cholera toxin (CT) may induce uncontrolled firing in recurrent networks of secretomotor neurons in the submucous plexus. This hypothesis was tested in chloralose-anesthetized rats in vivo. The secretory reflex response to graded intestinal distension was measured with or without prior exposure to luminal CT. The transmural potential difference (PD) was used as a marker for electrogenic chloride secretion. In controls, distension increased PD, and this response was reduced by the neural blocker tetrodotoxin given serosally and the vasoactive intestinal peptide (VIP) receptor antagonist [4Cl-d-Phe(6),Leu(17)]VIP (2 mug.min(-1).kg(-1) iv) but unaffected by the serotonin 5-HT(3) receptor antagonist granisetron, by the nicotinic receptor antagonist hexamethonium, by the muscarinic receptor antagonist atropine, or by the cyclooxygenase inhibitor indomethacin. Basal PD increased significantly with time in CT-exposed segments, an effect blocked by granisetron, by indomethacin, and by [4Cl-d-Phe(6),Leu(17)]VIP but not by hexamethonium or atropine. In contrast, once the increased basal PD produced by CT was established, [4Cl-d-Phe(6),Leu(17)]VIP and indomethacin had no significant effect, whereas granisetron and hexamethonium markedly depressed basal PD. CT significantly reduced the increase in PD produced by distension, an effect reversed by granisetron, indomethacin, and atropine. CT also activated a specific motility response to distension, repeated cluster contractions, but only in animals pretreated with granisetron, indomethacin, or atropine. These data are compatible with the hypothesis that CT induces uncontrolled activity in submucous secretory networks. Development of this state depends on 5-HT(3) receptors, VIP receptors, and prostaglandin synthesis, whereas its maintenance depends on 5-HT(3) and nicotinic receptors but not VIP receptors. The motility effects of CT (probably reflecting myenteric activity) are partially suppressed via a mechanism involving 5-HT(3) and muscarinic receptors and prostaglandin synthesis.
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Affiliation(s)
- Shirin Kordasti
- Dept. of Internal Medicine, Med pol 2, Sahlgren's University Hospital, University of Göteborg, S-413 45 Göteborg, Sweden
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