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Fouda MA, Ghovanloo MR, Ruben PC. Late sodium current: incomplete inactivation triggers seizures, myotonias, arrhythmias, and pain syndromes. J Physiol 2022; 600:2835-2851. [PMID: 35436004 DOI: 10.1113/jp282768] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 04/12/2022] [Indexed: 11/08/2022] Open
Abstract
Acquired and inherited dysfunction in voltage-gated sodium channels underlies a wide range of diseases. "In addition to the defects in trafficking and expression, sodium channelopathies are also caused by dysfunction in one or several gating properties, for instance activation or inactivation. Disruption of the channel inactivation leads to the increased late sodium current, which is a common defect in seizure disorders, cardiac arrhythmias skeletal muscle myotonia and pain. An increase in late sodium current leads to repetitive action potential in neurons and skeletal muscles, and prolonged action potential duration in the heart. In this topical review, we compare the effects of late sodium current in brain, heart, skeletal muscle, and peripheral nerves. Abstract figure legend Shows cartoon illustration of general Nav channel transitions between (1) resting, (2) open, and (3) fast inactivated states. Disruption of the inactivation process exacerbates (4) late sodium currents. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Mohamed A Fouda
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada.,Department of Pharmacology and Toxicology, Alexandria University, Alexandria, Egypt
| | | | - Peter C Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
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2
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Tetrodotoxin: A New Strategy to Treat Visceral Pain? Toxins (Basel) 2021; 13:toxins13070496. [PMID: 34357968 PMCID: PMC8310099 DOI: 10.3390/toxins13070496] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 07/08/2021] [Accepted: 07/13/2021] [Indexed: 12/13/2022] Open
Abstract
Visceral pain is one of the most common symptoms associated with functional gastrointestinal (GI) disorders. Although the origin of these symptoms has not been clearly defined, the implication of both the central and peripheral nervous systems in visceral hypersensitivity is well established. The role of several pathways in visceral nociception has been explored, as well as the influence of specific receptors on afferent neurons, such as voltage-gated sodium channels (VGSCs). VGSCs initiate action potentials and dysfunction of these channels has recently been associated with painful GI conditions. Current treatments for visceral pain generally involve opioid based drugs, which are associated with important side-effects and a loss of effectiveness or tolerance. Hence, efforts have been intensified to find new, more effective and longer-lasting therapies. The implication of VGSCs in visceral hypersensitivity has drawn attention to tetrodotoxin (TTX), a relatively selective sodium channel blocker, as a possible and promising molecule to treat visceral pain and related diseases. As such, here we will review the latest information regarding this toxin that is relevant to the treatment of visceral pain and the possible advantages that it may offer relative to other treatments, alone or in combination.
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Pellegrini C, Fornai M, Benvenuti L, Colucci R, Caputi V, Palazon-Riquelme P, Giron MC, Nericcio A, Garelli F, D'Antongiovanni V, Segnani C, Ippolito C, Nannipieri M, Lopez-Castejon G, Pelegrin P, Haskó G, Bernardini N, Blandizzi C, Antonioli L. NLRP3 at the crossroads between immune/inflammatory responses and enteric neuroplastic remodelling in a mouse model of diet-induced obesity. Br J Pharmacol 2021; 178:3924-3942. [PMID: 34000757 DOI: 10.1111/bph.15532] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 04/26/2021] [Accepted: 04/29/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND AND PURPOSE Enteric neurogenic/inflammation contributes to bowel dysmotility in obesity. We examined the role of NLRP3 in colonic neuromuscular dysfunctions in mice with high-fat diet (HFD)-induced obesity. EXPERIMENTAL APPROACH Wild-type C57BL/6J and NLRP3-KO (Nlrp3-/- ) mice were fed with HFD or standard diet for 8 weeks. The activation of inflammasome pathways in colonic tissues from obese mice was assessed. The role of NLRP3 in in vivo colonic transit and in vitro tachykininergic contractions and substance P distribution was evaluated. The effect of substance P on NLRP3 signalling was tested in cultured cells. KEY RESULTS HFD mice displayed increased body and epididymal fat weight, cholesterol levels, plasma resistin levels and plasma and colonic IL-1β levels, colonic inflammasome adaptor protein apoptosis-associated speck-like protein containing caspase-recruitment domain (ASC) and caspase-1 mRNA expression and ASC immunopositivity in macrophages. Colonic tachykininergic contractions were enhanced in HFD mice. HFD NLRP3-/- mice developed lower increase in body and epididymal fat weight, cholesterol levels, systemic and bowel inflammation. In HFD Nlrp3-/- mice, the functional alterations of tachykinergic pathways and faecal output were normalized. In THP-1 cells, substance P promoted IL-1β release. This effect was inhibited upon incubation with caspase-1 inhibitor or NK1 antagonist and not observed in ASC-/- cells. CONCLUSION AND IMPLICATIONS In obesity, NLRP3 regulates an interplay between the shaping of enteric immune/inflammatory responses and the activation of substance P/NK1 pathways underlying the onset of colonic dysmotility. Identifying NLRP3 as a therapeutic target for the treatment of bowel symptoms related to obesity.
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Affiliation(s)
- Carolina Pellegrini
- Department of Pharmacy, University of Pisa, Pisa, Italy.,Lydia Becker Institute of Immunology and Inflammation, Division of Infection, Immunity and Respiratory Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Matteo Fornai
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Laura Benvenuti
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Rocchina Colucci
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padua, Italy
| | - Valentina Caputi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padua, Italy.,APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Pablo Palazon-Riquelme
- Lydia Becker Institute of Immunology and Inflammation, Division of Infection, Immunity and Respiratory Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Maria Cecilia Giron
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padua, Italy
| | - Anna Nericcio
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padua, Italy
| | - Francesca Garelli
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padua, Italy
| | | | - Cristina Segnani
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Chiara Ippolito
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Monica Nannipieri
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Gloria Lopez-Castejon
- Lydia Becker Institute of Immunology and Inflammation, Division of Infection, Immunity and Respiratory Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Pablo Pelegrin
- Biomedical Research Institute of Murcia (IMIB-Arrixaca), Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain
| | - György Haskó
- Department of Anesthesiology, Columbia University, New York, New York, USA
| | - Nunzia Bernardini
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.,Interdepartmental Research Center "Nutraceuticals and Food for Health", University of Pisa, Pisa, Italy
| | - Corrado Blandizzi
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Luca Antonioli
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
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Perez-Medina AL, Galligan JJ. Optogenetic analysis of neuromuscular transmission in the colon of ChAT-ChR2-YFP BAC transgenic mice. Am J Physiol Gastrointest Liver Physiol 2019; 317:G569-G579. [PMID: 31411893 PMCID: PMC6879885 DOI: 10.1152/ajpgi.00089.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Propulsion of luminal content along the gut requires coordinated contractions and relaxations of gastrointestinal smooth muscles controlled by the enteric nervous system. Activation of excitatory motor neurons (EMNs) causes muscle contractions, whereas inhibitory motor neuron (IMN) activation causes muscle relaxation. EMNs release acetylcholine (ACh), which acts at muscarinic receptors on smooth muscle cells and adjacent interstitial cells of Cajal, causing excitatory junction potentials (EJPs). IMNs release ATP (or another purine) and nitric oxide to cause inhibitory junction potentials (IJPs) and muscle relaxation. We used commercially available choline acetyltransferase (ChAT)-channelrhodopsin-2 (ChR2)-yellow fluorescent protein (YFP) bacterial artificial chromosome (BAC) transgenic mice, which express ChR2 in cholinergic neurons, to study cholinergic neuromuscular transmission in the colon. Intracellular microelectrodes were used to record IJPs and EJPs from circular muscle cells. We used blue light stimulation (BLS, 470 nm, 20 mW/mm2) and electrical field stimulation (EFS) to activate myenteric neurons. EFS evoked IJPs only, whereas BLS evoked EJPs and IJPs. Mecamylamine (10 µM, nicotinic cholinergic receptor antagonist) reduced BLS-evoked IJPs by 50% but had no effect on electrically evoked IJPs. MRS 2179 (10 µM, a P2Y1 receptor antagonist) blocked BLS-evoked IJPs. MRS 2179 and Nω-nitro-l-arginine (100 µM, nitric oxide synthase inhibitor) isolated the EJP, which was blocked by scopolamine (1 µM, muscarinic ACh receptor antagonist). Immunohistochemistry revealed ChAT expression in ~88% of enhanced YFP (eYFP)-expressing neurons, whereas 12% of eYFP neurons expressed nitric oxide synthase. These data show that cholinergic interneurons synapse with EMNs and IMNs to cause contraction and relaxation of colonic smooth muscle.NEW & NOTEWORTHY Electrical stimulation of interganglionic connectives has been used widely to study synaptic transmission in the enteric nervous system. However, electrical stimulation will activate many types of neurons and nerve fibers, which complicates data interpretation. Optogenetic activation of enteric neurons using genetically modified mice expressing channelrhodopsin-2 in cholinergic neurons offers a new approach that provides more specificity for nerve stimulation when studying myenteric plexus nerve circuitry.
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Affiliation(s)
| | - James J. Galligan
- 1Department of Pharmacology & Toxicology, Michigan State University, East Lansing, Michigan,2Neuroscience Program, Michigan State University, East Lansing, Michigan
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Patejdl R, Gromann A, Bänsch D, Noack T. Effects of ajmaline on contraction patterns of isolated rat gastric antrum and portal vein smooth muscle strips and on neurogenic relaxations of gastric fundus. Pflugers Arch 2019; 471:995-1005. [PMID: 31044280 DOI: 10.1007/s00424-019-02279-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/03/2019] [Accepted: 04/24/2019] [Indexed: 12/23/2022]
Abstract
Class-I-antiarrhythmics like ajmaline are known to alter smooth muscle function, which may cause alterations in gastrointestinal motility. The effects of ajmaline on isolated gastric and portal vein smooth muscle and the underlying mechanisms are unknown. We studied the effects of ajmaline on the contractile patterns of isolated preparations of gastric antrum and portal vein from Wistar rats. The organ bath technique was used to measure spontaneous or pharmacologically induced isometric contractions. Changes in force observed after application of ajmaline or under control conditions are reported as % of the amplitude of an initial K+-induced contraction. Electric field stimulation was used to study neurogenic relaxations of gastric fundus smooth muscle. Ajmaline increased the amplitude of spontaneous contractions of muscle strips (portal vein: control 31.1 ± 15.2%, with 100 μM ajmaline 76.6 ± 32.3%, n = 9, p < 0.01; gastric antrum: control 9.5 ± 1.6%, with 100 μM ajmaline 63.9 ± 9.96%, n = 14, p < 0.01). The frequency of spontaneous activity was reduced in portal vein, but not in gastric antrum strips. The effects of ajmaline were not blocked by tetrodotoxin, L-nitroarginine methyl ester, or atropine. Ajmaline abolished coordinated neurogenic relaxations triggered by electric field stimulation and partly reversed the inhibition of GA spontaneous activity caused by the gap junction blocker carbenoxolone. Ajmaline enhances the amplitude of spontaneous contractions in rat gastric and portal vein smooth muscle. This effect may be accompanied, but not caused by an inhibition of enteric neurotransmission. Enhanced syncytial coupling as indicated by its ability to antagonize the effects of carbenoxolone is likely to underlie the enhancement of contractility.
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Affiliation(s)
- Robert Patejdl
- Oscar-Langendorff-Institut für Physiologie, Universitätsmedizin Rostock, Gertrudenstraße 9, 18057, Rostock, Germany.
| | - Alina Gromann
- Oscar-Langendorff-Institut für Physiologie, Universitätsmedizin Rostock, Gertrudenstraße 9, 18057, Rostock, Germany
| | - Dietmar Bänsch
- Department of Cardiac Electrophysiology, KMG Hospital Güstrow, Güstrow, Germany
| | - Thomas Noack
- Oscar-Langendorff-Institut für Physiologie, Universitätsmedizin Rostock, Gertrudenstraße 9, 18057, Rostock, Germany
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6
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Effects of diabetes mellitus on myenteric neuronal density and sodium channel expression in the rat ileum. Brain Res 2018; 1708:1-9. [PMID: 30500400 DOI: 10.1016/j.brainres.2018.11.041] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 11/09/2018] [Accepted: 11/26/2018] [Indexed: 12/25/2022]
Abstract
Diabetes mellitus (DM) may lead to gastrointestinal motility disorders. Rodent models of DM indicate the presence of morpho-functional abnormalities of the enteric nervous system. Here, we evaluated whether experimental DM can cause changes in the excitatory cholinergic fibers, neuronal density, and voltage-gated sodium channel (Nav) expression in the myenteric plexus of the ileum. After streptozotocin-induced hyperglycemia in female rats progressed for eight weeks, triple immunofluorescence labeling experiments revealed that the neuronal density in DM rats was significantly lower than that in control. On average, the density of total neurons reduced by 52.2% (p = 0.0001), cholinergic neurons by 50.0% (p = 0.0068), and nitrergic neurons by 54.8% (p = 0.0042). The number of neurons per ganglionic area was also significantly reduced (to 28.2% of total neurons, p = 0.0002; 27.7% of cholinergic neurons, p = 0.0002, and 32.1% of nitrergic neurons, p = 0.0016). Furthermore, the density of the cholinergic fibers at the surface of the longitudinal muscle was significantly reduced (DM: 24 ± 3%; p = 0.003, control: 41 ± 2%); however, western-blot analysis did not indicate a reduction in the expression of choline acetyltransferase (ChAT) in the DM group. The Nav1.6 isoform was detected in different myenteric neurons of the ileum. RT-qPCR data did not suggest an alteration of transcripts for ChAT, neuronal nitric oxide synthase, Nav1.3, Nav1.6, or Nav1.7. Our data support the view that chronic DM leads to a reduction of excitatory cholinergic fibers and neuronal density. However, changes in sodium channel expression pattern, which could cause neuronal dysfunction, were not detected.
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Abstract
Fever-associated seizures or epilepsy (FASE) is primarily characterised by the occurrence of a seizure or epilepsy usually accompanied by a fever. It is common in infants and children, and generally includes febrile seizures (FS), febrile seizures plus (FS+), Dravet syndrome (DS) and genetic epilepsy with febrile seizures plus (GEFSP). The aetiology of FASE is unclear. Genetic factors may play crucial roles in FASE. Mutations in certain genes may cause a wide spectrum of phenotypical overlap ranging from isolated FS, FS+ and GEFSP to DS. Synapse-associated proteins, postsynaptic GABAA receptor, and sodium channels play important roles in synaptic transmission. Mutations in these genes may involve in the pathogenesis of FASE. Elevated temperature promotes synaptic vesicle (SV) recycling and enlarges SV size, which may enhance synaptic transmission and contribute to FASE occurring. This review provides an overview of the loci, genes, underlying pathogenesis and the fever-inducing effect of FASE. It may provide a more comprehensive understanding of pathogenesis and contribute to the clinical diagnosis of FASE.
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Erickson A, Deiteren A, Harrington AM, Garcia‐Caraballo S, Castro J, Caldwell A, Grundy L, Brierley SM. Voltage-gated sodium channels: (Na V )igating the field to determine their contribution to visceral nociception. J Physiol 2018; 596:785-807. [PMID: 29318638 PMCID: PMC5830430 DOI: 10.1113/jp273461] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 01/02/2018] [Indexed: 12/19/2022] Open
Abstract
Chronic visceral pain, altered motility and bladder dysfunction are common, yet poorly managed symptoms of functional and inflammatory disorders of the gastrointestinal and urinary tracts. Recently, numerous human channelopathies of the voltage-gated sodium (NaV ) channel family have been identified, which induce either painful neuropathies, an insensitivity to pain, or alterations in smooth muscle function. The identification of these disorders, in addition to the recent utilisation of genetically modified NaV mice and specific NaV channel modulators, has shed new light on how NaV channels contribute to the function of neuronal and non-neuronal tissues within the gastrointestinal tract and bladder. Here we review the current pre-clinical and clinical evidence to reveal how the nine NaV channel family members (NaV 1.1-NaV 1.9) contribute to abdominal visceral function in normal and disease states.
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Affiliation(s)
- Andelain Erickson
- Visceral Pain Research Group, Human Physiology, Centre for Neuroscience, College of Medicine and Public HealthFlinders UniversityBedford ParkSouth Australia5042Australia
- Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, University of AdelaideSouth Australian Health and Medical Research Institute (SAHMRI)North TerraceAdelaideSouth Australia 5000Australia
| | - Annemie Deiteren
- Visceral Pain Research Group, Human Physiology, Centre for Neuroscience, College of Medicine and Public HealthFlinders UniversityBedford ParkSouth Australia5042Australia
- Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, University of AdelaideSouth Australian Health and Medical Research Institute (SAHMRI)North TerraceAdelaideSouth Australia 5000Australia
| | - Andrea M. Harrington
- Visceral Pain Research Group, Human Physiology, Centre for Neuroscience, College of Medicine and Public HealthFlinders UniversityBedford ParkSouth Australia5042Australia
- Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, University of AdelaideSouth Australian Health and Medical Research Institute (SAHMRI)North TerraceAdelaideSouth Australia 5000Australia
| | - Sonia Garcia‐Caraballo
- Visceral Pain Research Group, Human Physiology, Centre for Neuroscience, College of Medicine and Public HealthFlinders UniversityBedford ParkSouth Australia5042Australia
- Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, University of AdelaideSouth Australian Health and Medical Research Institute (SAHMRI)North TerraceAdelaideSouth Australia 5000Australia
| | - Joel Castro
- Visceral Pain Research Group, Human Physiology, Centre for Neuroscience, College of Medicine and Public HealthFlinders UniversityBedford ParkSouth Australia5042Australia
- Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, University of AdelaideSouth Australian Health and Medical Research Institute (SAHMRI)North TerraceAdelaideSouth Australia 5000Australia
| | - Ashlee Caldwell
- Visceral Pain Research Group, Human Physiology, Centre for Neuroscience, College of Medicine and Public HealthFlinders UniversityBedford ParkSouth Australia5042Australia
- Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, University of AdelaideSouth Australian Health and Medical Research Institute (SAHMRI)North TerraceAdelaideSouth Australia 5000Australia
| | - Luke Grundy
- Visceral Pain Research Group, Human Physiology, Centre for Neuroscience, College of Medicine and Public HealthFlinders UniversityBedford ParkSouth Australia5042Australia
- Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, University of AdelaideSouth Australian Health and Medical Research Institute (SAHMRI)North TerraceAdelaideSouth Australia 5000Australia
| | - Stuart M. Brierley
- Visceral Pain Research Group, Human Physiology, Centre for Neuroscience, College of Medicine and Public HealthFlinders UniversityBedford ParkSouth Australia5042Australia
- Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, University of AdelaideSouth Australian Health and Medical Research Institute (SAHMRI)North TerraceAdelaideSouth Australia 5000Australia
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Bolz F, Kasper S, Bufe B, Zufall F, Pyrski M. Organization and Plasticity of Sodium Channel Expression in the Mouse Olfactory and Vomeronasal Epithelia. Front Neuroanat 2017; 11:28. [PMID: 28420967 PMCID: PMC5376585 DOI: 10.3389/fnana.2017.00028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 03/20/2017] [Indexed: 12/15/2022] Open
Abstract
To understand the molecular basis of neuronal excitation in the mammalian olfactory system, we conducted a systematic analysis of the organization of voltage-gated sodium (Nav) channel subunits in the main olfactory epithelium (MOE) and vomeronasal organ (VNO) of adult mice. We also analyzed changes in Nav channel expression during development in these two systems and during regeneration of the MOE. Quantitative PCR shows that Nav1.7 is the predominant isoform in both adult MOE and VNO. We detected pronounced immunoreactivity for Nav1.7 and Nav1.3 in axons of olfactory and vomeronasal sensory neurons (VSNs). Analysis of Nav1.2 and Nav1.6 revealed an unexpected subsystem-specific distribution. In the MOE, these Nav channels are absent from olfactory sensory neurons (OSNs) but present in non-neuronal olfactory cell types. In the VNO, Nav1.2 and Nav1.6 are confined to VSNs, with Nav1.2-immunoreactive somata solely present in the basal layer of the VNO. The subcellular localization of Nav1.3 and Nav1.7 in OSNs can change dramatically during periods of heightened plasticity in the MOE. During the first weeks of development and during regeneration of the olfactory epithelium following chemical lesion, expression of Nav1.3 and Nav1.7 is transiently enhanced in the somata of mature OSNs. Our results demonstrate a highly complex organization of Nav channel expression in the mouse olfactory system, with specific commonalities but also differences between the MOE and the VNO. On the basis of their subcellular localization, Nav1.3 and Nav1.7 should play major roles in action potential propagation in both MOE and VNO, whereas Nav1.2 and Nav1.6 are specific to the function of VSNs. The plasticity of Nav channel expression in OSNs during early development and recovery from injury could reflect important physiological requirements in a variety of activity-dependent mechanisms.
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Affiliation(s)
- Florian Bolz
- Center for Integrative Physiology and Molecular Medicine, Saarland UniversityHomburg, Germany
| | - Stephanie Kasper
- Center for Integrative Physiology and Molecular Medicine, Saarland UniversityHomburg, Germany
| | - Bernd Bufe
- Center for Integrative Physiology and Molecular Medicine, Saarland UniversityHomburg, Germany
| | - Frank Zufall
- Center for Integrative Physiology and Molecular Medicine, Saarland UniversityHomburg, Germany
| | - Martina Pyrski
- Center for Integrative Physiology and Molecular Medicine, Saarland UniversityHomburg, Germany
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Tompkins JD, Clason TA, Hardwick JC, Girard BM, Merriam LA, May V, Parsons RL. Activation of MEK/ERK signaling contributes to the PACAP-induced increase in guinea pig cardiac neuron excitability. Am J Physiol Cell Physiol 2016; 311:C643-C651. [PMID: 27488668 DOI: 10.1152/ajpcell.00164.2016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/01/2016] [Indexed: 01/12/2023]
Abstract
Pituitary adenylate cyclase (PAC)-activating polypeptide (PACAP) peptides (Adcyap1) signaling at the selective PAC1 receptor (Adcyap1r1) participate in multiple homeostatic and stress-related responses, yet the cellular mechanisms underlying PACAP actions remain to be completely elucidated. PACAP/PAC1 receptor signaling increases excitability of neurons within the guinea pig cardiac ganglia, and as these neurons are readily accessible, this neuronal system is particularly amenable to study of PACAP modulation of ionic conductances. The present study investigated how PACAP activation of MEK/ERK signaling contributed to the peptide-induced increase in cardiac neuron excitability. Treatment with the MEK inhibitor PD 98059 blocked PACAP-stimulated phosphorylated ERK and, in parallel, suppressed the increase in cardiac neuron excitability. However, PD 98059 did not blunt the ability of PACAP to enhance two inward ionic currents, one flowing through hyperpolarization-activated nonselective cationic channels (Ih) and another flowing through low-voltage-activated calcium channels (IT), which support the peptide-induced increase in excitability. Thus a PACAP- and MEK/ERK-sensitive, voltage-dependent conductance(s), in addition to Ih and IT, modulates neuronal excitability. Despite prior work implicating PACAP downregulation of the KV4.2 potassium channel in modulation of excitability in other cells, treatment with the KV4.2 current blocker 4-aminopyridine did not replicate the PACAP-induced increase in excitability in cardiac neurons. However, cardiac neurons express the ERK target, the NaV1.7 sodium channel, and treatment with the selective NaV1.7 channel inhibitor PF-04856264 decreased the PACAP modulation of excitability. From these results, PACAP/PAC1 activation of MEK/ERK signaling may phosphorylate the NaV1.7 channel, enhancing sodium currents near the threshold, an action contributing to repetitive firing of the cardiac neurons exposed to PACAP.
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Affiliation(s)
- John D Tompkins
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California
| | - Todd A Clason
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
| | | | - Beatrice M Girard
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
| | - Laura A Merriam
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
| | - Victor May
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
| | - Rodney L Parsons
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
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Hetz S, Acikgoez A, Moll C, Jahnke HG, Robitzki AA, Metzger R, Metzger M. Age-related gene expression analysis in enteric ganglia of human colon after laser microdissection. Front Aging Neurosci 2014; 6:276. [PMID: 25360110 PMCID: PMC4197768 DOI: 10.3389/fnagi.2014.00276] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 09/24/2014] [Indexed: 01/16/2023] Open
Abstract
The enteric nervous system (ENS) poses the intrinsic innervation of the gastrointestinal tract and plays a critical role for all stages of postnatal life. There is increasing scientific and clinical interest in acquired or age-related gastrointestinal dysfunctions that can be manifested in diseases such as gut constipation or fecal incontinence. In this study, we sought to analyze age-dependent changes in the gene expression profile of the human ENS, particularly in the myenteric plexus. Therefore, we used the laser microdissection technique which has been proven as a feasible tool to analyze distinct cell populations within heterogeneously composed tissues. Full biopsy gut samples were prepared from children (4-12 months), middle aged (48-58 years) and aged donors (70-95 years). Cryosections were histologically stained with H&E, the ganglia of the myenteric plexus identified and RNA isolated using laser microdissection technique. Quantitative PCR was performed for selected neural genes, neurotransmitters and receptors. Data were confirmed on protein level using NADPH-diaphorase staining and immunohistochemistry. As result, we demonstrate age-associated alterations in site-specific gene expression pattern of the ENS. Thus, in the adult and aged distal parts of the colon a marked decrease in relative gene expression of neural key genes like NGFR, RET, NOS1 and a concurrent increase of CHAT were observed. Further, we detected notable regional differences of RET, CHAT, TH, and S100B comparing gene expression in aged proximal and distal colon. Interestingly, markers indicating cellular senescence or oxidative stress (SNCA, CASP3, CAT, SOD2, and TERT) were largely unchanged within the ENS. For the first time, our study also describes the age-dependent expression pattern of all major sodium channels within the ENS. Our results are in line with previous studies showing spatio-temporal differences within the mammalian ENS.
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Affiliation(s)
- Susan Hetz
- CELLT Research Group, Translational Centre for Regenerative Medicine, University of Leipzig Leipzig, Germany
| | - Ali Acikgoez
- Department of General and Visceral Surgery, St. George's Hospital Leipzig, Germany
| | - Corinna Moll
- Department of Tissue Engineering and Regenerative Medicine, University Hospital Wuerzburg Wuerzburg, Germany
| | - Heinz-Georg Jahnke
- Division of Molecular biological-biochemical Processing Technology, Center for Biotechnology and Biomedicine (BBZ), University of Leipzig Leipzig, Germany
| | - Andrea A Robitzki
- Division of Molecular biological-biochemical Processing Technology, Center for Biotechnology and Biomedicine (BBZ), University of Leipzig Leipzig, Germany
| | - Roman Metzger
- Department of Pediatric Surgery, University of Leipzig Leipzig, Germany
| | - Marco Metzger
- CELLT Research Group, Translational Centre for Regenerative Medicine, University of Leipzig Leipzig, Germany ; Department of Tissue Engineering and Regenerative Medicine, University Hospital Wuerzburg Wuerzburg, Germany
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12
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Chambers JD, Bornstein JC, Gwynne RM, Koussoulas K, Thomas EA. A detailed, conductance-based computer model of intrinsic sensory neurons of the gastrointestinal tract. Am J Physiol Gastrointest Liver Physiol 2014; 307:G517-32. [PMID: 25012843 DOI: 10.1152/ajpgi.00228.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Intrinsic sensory neurons (ISNs) of the enteric nervous system respond to stimuli such as muscle tension, muscle length, distortion of the mucosa, and the chemical content in the lumen. ISNs form recurrent networks that probably drive many intestinal motor patterns and reflexes. ISNs express a large number of voltage- and calcium-gated ion channels, some of which are modified by inflammation or repeated physiological stimuli, but how interactions between different ionic currents in ISNs produce both normal and pathological behaviors in the intestine remains unclear. We constructed a model of ISNs including voltage-gated sodium and potassium channels, N-type calcium channels, big conductance calcium-dependent potassium (BK) channels, calcium-dependent nonspecific cation channels (NSCa), intermediate conductance calcium-dependent potassium (IK) channels, hyperpolarization-activated cation (Ih) channels, and internal calcium dynamics. The model was based on data from the literature and our electrophysiological studies. The model reproduced responses to short or long depolarizing current pulses and responses to long hyperpolarizing current pulses. Sensitivity analysis showed that Ih, IK, NSCa, and BK have the largest influence on the number of action potentials observed during prolonged depolarizations. The model also predicts that changes to the voltage of activation for Ih have a large influence on excitability, but changes to the time constant of activation for Ih have a minor effect. Our model identifies how interactions between different iconic currents influence the excitability of ISNs and highlights an important role for Ih in enteric neuroplasticity resulting from disease.
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Affiliation(s)
- Jordan D Chambers
- Department of Physiology, University of Melbourne, Parkville, Victoria, Australia; and
| | - Joel C Bornstein
- Department of Physiology, University of Melbourne, Parkville, Victoria, Australia; and
| | - Rachel M Gwynne
- Department of Physiology, University of Melbourne, Parkville, Victoria, Australia; and
| | - Katerina Koussoulas
- Department of Physiology, University of Melbourne, Parkville, Victoria, Australia; and
| | - Evan A Thomas
- Florey Neuroscience Institutes, Parkville, Victoria, Australia
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Specialized functions of Nav1.5 and Nav1.9 channels in electrogenesis of myenteric neurons in intact mouse ganglia. J Neurosci 2014; 34:5233-44. [PMID: 24719102 DOI: 10.1523/jneurosci.0057-14.2014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Voltage-gated sodium (Nav) channels play a central role in gastrointestinal physiology because they transmit depolarizing impulses in enteric neurons, thereby enabling the coordination of intestinal motility. However, little is known about the ion channel machinery that specifies firing pattern of enteric neurons. Here, we used in situ patch-clamp recording of myenteric neurons from mice to define functionally the Nav channel subtypes responsible for the electrical signature of myenteric neurons. We found that mouse myenteric neurons exhibit two types of tetrodotoxin-resistant Na(+) currents: an early inactivating Na(+) current (INaT) and a persistent Na(+) current (INaP). INaT was encountered in all myenteric neurons, whereas INaP was preferentially found in Dogiel type II sensory neurons. Knock-out mouse studies, in combination with pharmacological assays, indicate that INaT is carried by the Scn5a-encoded "cardiac" Nav1.5, whereas INaP is attributed to the Scn11a-encoded Nav1.9. Current-clamp experiments show that Nav1.9 flows at subthreshold voltages, generating tonic firing. In addition, action potential (AP) clamp reveals that Nav1.5 contributes to the upstroke velocity of APs, whereas Nav1.9, which remains active during the falling phase, opposes AP repolarization. We developed a computational model of a Dogiel type II myenteric neuron that successfully reproduces all experimentally observed phenomena and highlights the differential roles of Nav1.5 and Nav1.9 in the control of excitability. Our data illustrate how excitability can be finely tuned to provide specific firing templates by the selective deployment of Nav1.5 and Nav1.9 isoforms. We propose that Nav-dependent ENS disorders of excitability may play important roles in the pathogenesis of digestive diseases.
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Electrophysiological characteristics of enteric neurons isolated from the immortomouse. Dig Dis Sci 2013; 58:1516-27. [PMID: 23371009 PMCID: PMC3664262 DOI: 10.1007/s10620-013-2557-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 01/01/2013] [Indexed: 12/09/2022]
Abstract
BACKGROUND Recently, two enteric neuronal cell lines, one fetal and the other post-natal (IM-PEN), have been developed from the H-2K(b)-tsA58 transgenic mouse (immortomouse). However, their electrophysiological properties are not known. The goal of this study was to determine the electrical excitability and ionic conductance of the immortalized postnatal enteric neuronal (IM-PEN) cell line. METHODS Whole cell patch clamp studies, immunohistochemistry and RT-PCR were performed on differentiated IM-PEN cells following propagation at 33 °C and differentiation at 37 °C. RESULTS Differentiated IM-PEN cells stained positively for the neuron specific markers βIII-tubulin and PGP9.5. The mRNA for several ion channels expressed in enteric neurons were detected by RT-PCR. In current clamp, the resting membrane potential was -24.6 ± 2.1 mV (n = 6) for IM-FEN and -29.8 ± 0.9 mV (n = 30) for IM-PEN. Current injections from Vh -80 mV resulted in passive responses but not action potentials. Depolarizing pulses in the whole cell voltage clamp configuration from Vh -80 mV elicited small nifedipine-sensitive inward currents. Additionally, outward currents with slow deactivating tail currents were blocked by niflumic acid and low chloride solution. A volume-regulated anion current was elicited by hypo-osmotic solution and inhibited by 10 μM DCPIB. Growth with rabbit gastrointestinal smooth muscle did not yield significant differences in the active properties of the IM-PEN cell line. Transient expression of L-type Ca(2+) channels produced large inward currents demonstrating a working mechanism for protein folding and transport. CONCLUSION The electrophysiological characteristics of IM-PEN cells suggest that chloride channels in IM-PEN cells play an important role in their resting state, and membrane trafficking of some of the ion channels may preclude their electrical excitability.
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Dib-Hajj SD, Yang Y, Black JA, Waxman SG. The NaV1.7 sodium channel: from molecule to man. Nat Rev Neurosci 2012; 14:49-62. [DOI: 10.1038/nrn3404] [Citation(s) in RCA: 377] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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16
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Wang W, Gu J, Li YQ, Tao YX. Are voltage-gated sodium channels on the dorsal root ganglion involved in the development of neuropathic pain? Mol Pain 2011; 7:16. [PMID: 21345196 PMCID: PMC3052185 DOI: 10.1186/1744-8069-7-16] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Accepted: 02/23/2011] [Indexed: 12/17/2022] Open
Abstract
Neuropathic pain is a common clinical condition. Current treatments are often inadequate, ineffective, or produce potentially severe adverse effects. Understanding the mechanisms that underlie the development and maintenance of neuropathic pain will be helpful in identifying new therapeutic targets and developing effective strategies for the prevention and/or treatment of this disorder. The genesis of neuropathic pain is reliant, at least in part, on abnormal spontaneous activity within sensory neurons. Therefore, voltage-gated sodium channels, which are essential for the generation and conduction of action potentials, are potential targets for treating neuropathic pain. However, preclinical studies have shown unexpected results because most pain-associated voltage-gated channels in the dorsal root ganglion are down-regulated after peripheral nerve injury. The role of dorsal root ganglion voltage-gated channels in neuropathic pain is still unclear. In this report, we describe the expression and distribution of voltage-gated sodium channels in the dorsal root ganglion. We also review evidence regarding changes in their expression under neuropathic pain conditions and their roles in behavioral responses in a variety of neuropathic pain models. We finally discuss their potential involvement in neuropathic pain.
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Affiliation(s)
- Wei Wang
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Abstract
Nociception is essential for survival whereas pathological pain is maladaptive and often unresponsive to pharmacotherapy. Voltage-gated sodium channels, Na(v)1.1-Na(v)1.9, are essential for generation and conduction of electrical impulses in excitable cells. Human and animal studies have identified several channels as pivotal for signal transmission along the pain axis, including Na(v)1.3, Na(v)1.7, Na(v)1.8, and Na(v)1.9, with the latter three preferentially expressed in peripheral sensory neurons and Na(v)1.3 being upregulated along pain-signaling pathways after nervous system injuries. Na(v)1.7 is of special interest because it has been linked to a spectrum of inherited human pain disorders. Here we review the contribution of these sodium channel isoforms to pain.
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Affiliation(s)
- Sulayman D Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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Dib-Hajj SD, Binshtok AM, Cummins TR, Jarvis MF, Samad T, Zimmermann K. Voltage-gated sodium channels in pain states: Role in pathophysiology and targets for treatment. ACTA ACUST UNITED AC 2009; 60:65-83. [DOI: 10.1016/j.brainresrev.2008.12.005] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/29/2008] [Indexed: 12/19/2022]
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Copel C, Osorio N, Crest M, Gola M, Delmas P, Clerc N. Activation of neurokinin 3 receptor increases Na(v)1.9 current in enteric neurons. J Physiol 2009; 587:1461-79. [PMID: 19204045 DOI: 10.1113/jphysiol.2009.169409] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The intrinsic primary afferent neurons (IPANs) of the guinea pig enteric nervous system express Na(v)1.9 sodium channels that produce a persistent TTX-resistant current having a low activation threshold and slow gating kinetics. These neurons receive slow EPSPs induced mainly by the activation of neurokinin 3 receptors (NK3r). Here, we demonstrate that senktide, a specific NK3r agonist, potentiates the Na(v)1.9 current (I(Nav1.9)) in IPANs. Using whole-cell patch-clamp recordings from IPANs in duodenum longitudinal muscle/myenteric plexus preparations, we show that short (1-5 s) and long (up to 1 min) applications of senktide, increase the I(Nav1.9) peak current up to 13-fold. The effect, blocked by a NK3r antagonist SB235375 is transient, lasting approximately 2 min and is due to a negative shift of the activation voltage by approximately 20 mV and of fast inactivation by approximately 10 mV. As a consequence, the window current resulting from the product of the activation and fast inactivation curves is shifted and enlarged. The transient effect of senktide is likely to be due to the fast desensitization of NK3r. Protein kinase C (PKC) activation with phorbol or oleoyl acetylglycerol also increases I(Nav1.9), although persistently, by inducing similar voltage-dependent changes. Current-clamp experiments showed that I(Nav1.9) modulation by senktide lowers action potential threshold and increases excitability. The increase in I(Nav1.9) by NK3r activation is also likely to amplify slow EPSPs generated in the IPANs. These changes in excitability potentially have a profound effect on the entire enteric synaptic circuit and ultimately on gut motility and secretion.
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Affiliation(s)
- Carine Copel
- UMR, CNRS/Université de la Méditerranée/Université Paul Cézanne, Marseille, France
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Dib‐Hajj SD, Yang Y, Waxman SG. Chapter 4 Genetics and Molecular Pathophysiology of Nav1.7‐Related Pain Syndromes. ADVANCES IN GENETICS 2008; 63:85-110. [DOI: 10.1016/s0065-2660(08)01004-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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