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Maxion A, Kutafina E, Dohrn MF, Sacré P, Lampert A, Tigerholm J, Namer B. A modelling study to dissect the potential role of voltage-gated ion channels in activity-dependent conduction velocity changes as identified in small fiber neuropathy patients. Front Comput Neurosci 2023; 17:1265958. [PMID: 38156040 PMCID: PMC10752960 DOI: 10.3389/fncom.2023.1265958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 10/25/2023] [Indexed: 12/30/2023] Open
Abstract
Objective Patients with small fiber neuropathy (SFN) suffer from neuropathic pain, which is still a therapeutic problem. Changed activation patterns of mechano-insensitive peripheral nerve fibers (CMi) could cause neuropathic pain. However, there is sparse knowledge about mechanisms leading to CMi dysfunction since it is difficult to dissect specific molecular mechanisms in humans. We used an in-silico model to elucidate molecular causes of CMi dysfunction as observed in single nerve fiber recordings (microneurography) of SFN patients. Approach We analyzed microneurography data from 97 CMi-fibers from healthy individuals and 34 of SFN patients to identify activity-dependent changes in conduction velocity. Using the NEURON environment, we adapted a biophysical realistic preexisting CMi-fiber model with ion channels described by Hodgkin-Huxley dynamics for identifying molecular mechanisms leading to those changes. Via a grid search optimization, we assessed the interplay between different ion channels, Na-K-pump, and resting membrane potential. Main results Changing a single ion channel conductance, Na-K-pump or membrane potential individually is not sufficient to reproduce in-silico CMi-fiber dysfunction of unchanged activity-dependent conduction velocity slowing and quicker normalization of conduction velocity after stimulation as observed in microneurography. We identified the best combination of mechanisms: increased conductance of potassium delayed-rectifier and decreased conductance of Na-K-pump and depolarized membrane potential. When the membrane potential is unchanged, opposite changes in Na-K-pump and ion channels generate the same effect. Significance Our study suggests that not one single mechanism accounts for pain-relevant changes in CMi-fibers, but a combination of mechanisms. A depolarized membrane potential, as previously observed in patients with neuropathic pain, leads to changes in the contribution of ion channels and the Na-K-pump. Thus, when searching for targets for the treatment of neuropathic pain, combinations of several molecules in interplay with the membrane potential should be regarded.
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Affiliation(s)
- Anna Maxion
- Research Group Neuroscience, Interdisciplinary Centre for Clinical Research within the Faculty of Medicine at the RWTH Aachen University, Aachen, Germany
| | - Ekaterina Kutafina
- Institute of Medical Informatics, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Maike F. Dohrn
- Department of Neurology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Pierre Sacré
- Department of Electrical Engineering and Computer Science, University of Liège, Liège, Belgium
| | - Angelika Lampert
- Institute of Neurophysiology, Uniklinik RWTH Aachen University Aachen, Aachen, Germany
| | - Jenny Tigerholm
- Joint Research Center for Computational Biomedicine, RWTH Aachen, Aachen, Germany
| | - Barbara Namer
- Research Group Neuroscience, Interdisciplinary Centre for Clinical Research within the Faculty of Medicine at the RWTH Aachen University, Aachen, Germany
- Institute of Neurophysiology, RWTH Aachen University, Aachen, Germany
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany
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Sierra-Marquez J, Willuweit A, Schöneck M, Bungert-Plümke S, Gehlen J, Balduin C, Müller F, Lampert A, Fahlke C, Guzman RE. ClC-3 regulates the excitability of nociceptive neurons and is involved in inflammatory processes within the spinal sensory pathway. Front Cell Neurosci 2022; 16:920075. [PMID: 37124866 PMCID: PMC10134905 DOI: 10.3389/fncel.2022.920075] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 07/28/2022] [Indexed: 11/13/2022] Open
Abstract
ClC-3 Cl–/H+ exchangers are expressed in multiple endosomal compartments and likely modify intra-endosomal pH and [Cl–] via the stoichiometrically coupled exchange of two Cl– ions and one H+. We studied pain perception in Clcn3–/– mice and found that ClC-3 not only modifies the electrical activity of peripheral nociceptors but is also involved in inflammatory processes in the spinal cord. We demonstrate that ClC-3 regulates the number of Nav and Kv ion channels in the plasma membrane of dorsal root ganglion (DRG) neurons and that these changes impair the age-dependent decline in excitability of sensory neurons. To distinguish the role of ClC-3 in Cl–/H+ exchange from its other functions in pain perception, we used mice homozygous for the E281Q ClC-3 point mutation (Clcn3E281Q/E281Q), which completely eliminates transport activity. Since ClC-3 forms heterodimers with ClC-4, we crossed these animals with Clcn4–/– to obtain mice completely lacking in ClC-3-associated endosomal chloride–proton transport. The electrical properties of Clcn3E281Q/E281Q/Clcn4–/– DRG neurons were similar to those of wild-type cells, indicating that the age-dependent adjustment of neuronal excitability is independent of ClC-3 transport activity. Both Clcn3–/– and Clcn3E281Q/E281Q/Clcn4–/– animals exhibited microglial activation in the spinal cord, demonstrating that competent ClC-3 transport is needed to maintain glial cell homeostasis. Our findings illustrate how reduced Cl–/H+ exchange contributes to inflammatory responses and demonstrate a role for ClC-3 in the homeostatic regulation of neuronal excitability beyond its function in endosomal ion balance.
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Affiliation(s)
- Juan Sierra-Marquez
- Institute of Biological Information Processing, Molecular and Cellular Physiology (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | - Antje Willuweit
- Medical Imaging Physics, Institute of Neuroscience and Medicine (INM-4), Forschungszentrum Jülich, Jülich, Germany
| | - Michael Schöneck
- Medical Imaging Physics, Institute of Neuroscience and Medicine (INM-4), Forschungszentrum Jülich, Jülich, Germany
| | - Stefanie Bungert-Plümke
- Institute of Biological Information Processing, Molecular and Cellular Physiology (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | - Jana Gehlen
- Institute of Biological Information Processing, Molecular and Cellular Physiology (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | - Carina Balduin
- Medical Imaging Physics, Institute of Neuroscience and Medicine (INM-4), Forschungszentrum Jülich, Jülich, Germany
| | - Frank Müller
- Institute of Biological Information Processing, Molecular and Cellular Physiology (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | | | - Christoph Fahlke
- Institute of Biological Information Processing, Molecular and Cellular Physiology (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | - Raul E. Guzman
- Institute of Biological Information Processing, Molecular and Cellular Physiology (IBI-1), Forschungszentrum Jülich, Jülich, Germany
- *Correspondence: Raul E. Guzman,
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Multitarget nociceptor sensitization by a promiscuous peptide from the venom of the King Baboon spider. Proc Natl Acad Sci U S A 2022; 119:2110932119. [PMID: 35074873 PMCID: PMC8812547 DOI: 10.1073/pnas.2110932119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2021] [Indexed: 12/15/2022] Open
Abstract
The King Baboon spider, Pelinobius muticus, is a burrowing African tarantula. Its impressive size and appealing coloration are tempered by reports describing severe localized pain, swelling, itchiness, and muscle cramping after accidental envenomation. Hyperalgesia is the most prominent symptom after bites from P. muticus, but the molecular basis by which the venom induces pain is unknown. Proteotranscriptomic analysis of P. muticus venom uncovered a cysteine-rich peptide, δ/κ-theraphotoxin-Pm1a (δ/κ-TRTX-Pm1a), that elicited nocifensive behavior when injected into mice. In small dorsal root ganglion neurons, synthetic δ/κ-TRTX-Pm1a (sPm1a) induced hyperexcitability by enhancing tetrodotoxin-resistant sodium currents, impairing repolarization and lowering the threshold of action potential firing, consistent with the severe pain associated with envenomation. The molecular mechanism of nociceptor sensitization by sPm1a involves multimodal actions over several ion channel targets, including NaV1.8, KV2.1, and tetrodotoxin-sensitive NaV channels. The promiscuous targeting of peptides like δ/κ-TRTX-Pm1a may be an evolutionary adaptation in pain-inducing defensive venoms.
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Velichkova AN, Coleman SE, Torsney C. Postoperative pain facilitates rat C-fibre activity-dependent slowing and induces thermal hypersensitivity in a sex-dependent manner. Br J Anaesth 2022; 128:718-733. [DOI: 10.1016/j.bja.2021.10.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 10/05/2021] [Accepted: 10/26/2021] [Indexed: 11/02/2022] Open
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Bonalume V, Caffino L, Castelnovo LF, Faroni A, Liu S, Hu J, Milanese M, Bonanno G, Sohns K, Hoffmann T, De Col R, Schmelz M, Fumagalli F, Magnaghi V, Carr R. Axonal GABA A stabilizes excitability in unmyelinated sensory axons secondary to NKCC1 activity. J Physiol 2021; 599:4065-4084. [PMID: 34174096 DOI: 10.1113/jp279664] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 06/08/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS GABA depolarized sural nerve axons and increased the electrical excitability of C-fibres via GABAA receptor. Axonal excitability responses to GABA increased monotonically with the rate of action potential firing. Action potential activity in unmyelinated C-fibres is coupled to Na-K-Cl cotransporter type 1 (NKCC1) loading of axonal chloride. Activation of axonal GABAA receptor stabilized C-fibre excitability during prolonged low frequency (2.5 Hz) firing. NKCC1 maintains intra-axonal chloride to provide feed-forward stabilization of C-fibre excitability and thus support sustained firing. ABSTRACT GABAA receptor (GABAA R)-mediated depolarization of dorsal root ganglia (DRG) axonal projections in the spinal dorsal horn is implicated in pre-synaptic inhibition. Inhibition, in this case, is predicated on an elevated intra-axonal chloride concentration and a depolarizing GABA response. In the present study, we report that the peripheral axons of DRG neurons are also depolarized by GABA and this results in an increase in the electrical excitability of unmyelinated C-fibre axons. GABAA R agonists increased axonal excitability, whereas GABA excitability responses were blocked by GABAA R antagonists and were absent in mice lacking the GABAA R β3 subunit selectively in DRG neurons (AdvillinCre or snsCre ). Under control conditions, excitability responses to GABA became larger at higher rates of electrical stimulation (0.5-2.5 Hz). However, during Na-K-Cl cotransporter type 1 (NKCC1) blockade, the electrical stimulation rate did not affect GABA response size, suggesting that NKCC1 regulation of axonal chloride is coupled to action potential firing. To examine this, activity-dependent conduction velocity slowing (activity-dependent slowing; ADS) was used to quantify C-fibre excitability loss during a 2.5 Hz challenge. ADS was reduced by GABAA R agonists and exacerbated by either GABAA R antagonists, β3 deletion or NKCC1 blockade. This illustrates that activation of GABAA R stabilizes C-fibre excitability during sustained firing. We posit that NKCC1 acts in a feed-forward manner to maintain an elevated intra-axonal chloride in C-fibres during ongoing firing. The resulting chloride gradient can be utilized by GABAA R to stabilize axonal excitability. The data imply that therapeutic strategies targeting axonal chloride regulation at peripheral loci of pain and itch may curtail aberrant firing in C-fibres.
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Affiliation(s)
- Veronica Bonalume
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Lucia Caffino
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Luca F Castelnovo
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
- Marine Science Institute, University of Texas at Austin, Port Aransas, TX, USA
| | - Alessandro Faroni
- Blond McIndoe Laboratories, Division of Cell Matrix Biology and Regenerative Medicine, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Sheng Liu
- Institute of Pharmacology, Heidelberg University, Mannheim, Germany
| | - Jing Hu
- Institute of Pharmacology, Heidelberg University, Mannheim, Germany
| | - Marco Milanese
- Department of Pharmacy (DIFAR), Pharmacology and Toxicology Unit, Università degli Studi di Genova, Genova, Italy
| | - Giambattista Bonanno
- Department of Pharmacy (DIFAR), Pharmacology and Toxicology Unit, Università degli Studi di Genova, Genova, Italy
- Ospedale Policlinico San Martino, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Genova, Italy
| | - Kyra Sohns
- Experimental Pain Research, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Tal Hoffmann
- Institute for Physiology and Pathophysiology, Friedrich-Alexander University, Erlangen, Germany
| | - Roberto De Col
- Experimental Pain Research, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Martin Schmelz
- Experimental Pain Research, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Fabio Fumagalli
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Valerio Magnaghi
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Richard Carr
- Experimental Pain Research, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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Pelot NA, Catherall DC, Thio BJ, Titus ND, Liang ED, Henriquez CS, Grill WM. Excitation properties of computational models of unmyelinated peripheral axons. J Neurophysiol 2021; 125:86-104. [PMID: 33085556 PMCID: PMC8087387 DOI: 10.1152/jn.00315.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 09/09/2020] [Accepted: 09/14/2020] [Indexed: 12/19/2022] Open
Abstract
Biophysically based computational models of nerve fibers are important tools for designing electrical stimulation therapies, investigating drugs that affect ion channels, and studying diseases that affect neurons. Although peripheral nerves are primarily composed of unmyelinated axons (i.e., C-fibers), most modeling efforts focused on myelinated axons. We implemented the single-compartment model of vagal afferents from Schild et al. (1994) (Schild JH, Clark JW, Hay M, Mendelowitz D, Andresen MC, Kunze DL. J Neurophysiol 71: 2338-2358, 1994) and extended the model into a multicompartment axon, presenting the first cable model of a C-fiber vagal afferent. We also implemented the updated parameters from the Schild and Kunze (1997) model (Schild JH, Kunze DL. J Neurophysiol 78: 3198-3209, 1997). We compared the responses of these novel models with those of three published models of unmyelinated axons (Rattay F, Aberham M. IEEE Trans Biomed Eng 40: 1201-1209, 1993; Sundt D, Gamper N, Jaffe DB. J Neurophysiol 114: 3140-3153, 2015; Tigerholm J, Petersson ME, Obreja O, Lampert A, Carr R, Schmelz M, Fransén E. J Neurophysiol 111: 1721-1735, 2014) and with experimental data from single-fiber recordings. Comparing the two models by Schild et al. (1994, 1997) revealed that differences in rest potential and action potential shape were driven by changes in maximum conductances rather than changes in sodium channel dynamics. Comparing the five model axons, the conduction speeds and strength-duration responses were largely within expected ranges, but none of the models captured the experimental threshold recovery cycle-including a complete absence of late subnormality in the models-and their action potential shapes varied dramatically. The Tigerholm et al. (2014) model best reproduced the experimental data, but these modeling efforts make clear that additional data are needed to parameterize and validate future models of autonomic C-fibers.NEW & NOTEWORTHY Peripheral nerves are primarily composed of unmyelinated axons, and there is growing interest in electrical stimulation of the autonomic nervous system to treat various diseases. We present the first cable model of an unmyelinated vagal nerve fiber and compare its ion channel isoforms and conduction responses with other published models of unmyelinated axons, establishing important tools for advancing modeling of autonomic nerves.
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Affiliation(s)
- Nicole A Pelot
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - David C Catherall
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Brandon J Thio
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Nathan D Titus
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Edward D Liang
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Craig S Henriquez
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
- Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina
- Department of Neurobiology, Duke University, Durham, North Carolina
- Department of Neurosurgery, Duke University, Durham, North Carolina
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7
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Tigerholm J, Hoberg TN, Brønnum D, Vittinghus M, Frahm KS, Mørch CD. Small and large cutaneous fibers display different excitability properties to slowly increasing ramp pulses. J Neurophysiol 2020; 124:883-894. [PMID: 32783585 DOI: 10.1152/jn.00629.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The excitability of large nerve fibers is reduced when their membrane potential is slowly depolarizing, i.e., the fibers display accommodation. The aim of this study was to assess accommodation in small (mainly Aδ) and large (Aβ) cutaneous sensory nerve fibers using the perception threshold tracking (PTT) technique. Linearly increasing ramp currents (1 ms-200 ms) were used to assess the excitability of the nerve fibers by cutaneous electrical stimulation. To investigate the PPT technique's ability to preferentially activate different fiber types, topical application of lidocaine/prilocaine (EMLA) or a placebo cream was applied. By means of computational modeling, the underlying mechanisms governing the perception threshold in the two fiber types was studied. The axon models included the voltage-gated ion channels: transient TTX-sensitive sodium current, transient TTX-resistant sodium current (NaTTXr), persistent sodium current, delayed rectifier potassium channel (KDr), slow potassium channel, and hyperpolarization-activated current. Large fibers displayed accommodation, whereas small fibers did not display accommodation (P < 0.05). For the pin electrode, a significant interaction was observed between cream (EMLA or placebo) and pulse duration (P < 0.05); for the patch electrode, there was no significant interaction between cream and duration, which supports the pin electrode's preferential activation of small fibers. The results from the computational model suggested that differences in accommodation between the two fiber types may originate from selective expression of voltage-gated ion channels, particularly the transient NaTTXr and/or KDr. The PTT technique could assess the excitability changes during accommodation in different nerve fibers. Therefore, the PTT technique may be a useful tool for studying excitability in nerve fibers in both healthy and pathological conditions.NEW & NOTEWORTHY When large nerve fibers are stimulated by long, slowly increasing electrical pulses, interactive mechanisms counteract the stimulation, which is called accommodation. The perception threshold tracking technique was able to assess accommodation in both small and large fibers. The novelty of this study is that large fibers displayed accommodation, whereas small fibers did not. Additionally, the difference in accommodation between the fiber could be linked to expression of voltage-gated ion channels by means of computational modeling.
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Affiliation(s)
- Jenny Tigerholm
- Integrative Neuroscience Group, Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Tatiana Nielson Hoberg
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Dorthe Brønnum
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.,Centre for Clinical Research, North Denmark Regional Hospital, Hjørring, Denmark
| | - Mette Vittinghus
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.,It-center for Telemedicin, Region Midtjylland, Aarhus N, Denmark
| | - Ken Steffen Frahm
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.,Integrative Neuroscience Group, Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Carsten Dahl Mørch
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.,Integrative Neuroscience Group, Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
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Slow depolarizing stimuli differentially activate mechanosensitive and silent C nociceptors in human and pig skin. Pain 2020; 161:2119-2128. [DOI: 10.1097/j.pain.0000000000001912] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 04/08/2020] [Indexed: 01/10/2023]
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Dynamical mechanism for conduction failure behavior of action potentials related to pain information transmission. Neurocomputing 2020. [DOI: 10.1016/j.neucom.2019.12.114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Hugosdottir R, Mørch CD, Jørgensen CK, Nielsen CW, Olsen MV, Pedersen MJ, Tigerholm J. Altered excitability of small cutaneous nerve fibers during cooling assessed with the perception threshold tracking technique. BMC Neurosci 2019; 20:47. [PMID: 31481024 PMCID: PMC6724327 DOI: 10.1186/s12868-019-0527-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 08/22/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND There is a need for new approaches to increase the knowledge of the membrane excitability of small nerve fibers both in healthy subjects, as well as during pathological conditions. Our research group has previously developed the perception threshold tracking technique to indirectly assess the membrane properties of peripheral small nerve fibers. In the current study, a new approach for studying membrane excitability by cooling small fibers, simultaneously with applying a slowly increasing electrical stimulation current, is evaluated. The first objective was to examine whether altered excitability during cooling could be detected by the perception threshold tracking technique. The second objective was to computationally model the underlying ionic current that could be responsible for cold induced alteration of small fiber excitability. The third objective was to evaluate whether computational modelling of cooling and electrical simulation can be used to generate hypotheses of ionic current changes in small fiber neuropathy. RESULTS The excitability of the small fibers was assessed by the perception threshold tracking technique for the two temperature conditions, 20 °C and 32 °C. A detailed multi-compartment model was developed, including the ionic currents: NaTTXs, NaTTXr, NaP, KDr, KM, KLeak, KA, and Na/K-ATPase. The perception thresholds for the two long duration pulses (50 and 100 ms) were reduced when the skin temperature was lowered from 32 to 20 °C (p < 0.001). However, no significant effects were observed for the shorter durations (1 ms, p = 0.116; 5 ms p = 0.079, rmANOVA, Sidak). The computational model predicted that the reduction in the perception thresholds related to long duration pulses may originate from a reduction of the KLeak channel and the Na/K-ATPase. For short durations, the effect cancels out due to a reduction of the transient TTX resistant sodium current (Nav1.8). Additionally, the result from the computational model indicated that cooling simultaneously with electrical stimulation, may increase the knowledge regarding pathological alterations of ionic currents. CONCLUSION Cooling may alter the ionic current during electrical stimulation and thereby provide additional information regarding membrane excitability of small fibers in healthy subjects and potentially also during pathological conditions.
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Affiliation(s)
- Rosa Hugosdottir
- Center of Neuroplasticity and Pain, SMI®, Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7D3, 9220, Aalborg, Denmark
| | - Carsten Dahl Mørch
- Center of Neuroplasticity and Pain, SMI®, Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7D3, 9220, Aalborg, Denmark
| | - Cecilia Klitgaard Jørgensen
- Center of Neuroplasticity and Pain, SMI®, Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7D3, 9220, Aalborg, Denmark
| | - Camilla Winther Nielsen
- Center of Neuroplasticity and Pain, SMI®, Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7D3, 9220, Aalborg, Denmark
| | - Mathias Vassard Olsen
- Center of Neuroplasticity and Pain, SMI®, Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7D3, 9220, Aalborg, Denmark
| | - Mads Jozwiak Pedersen
- Center of Neuroplasticity and Pain, SMI®, Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7D3, 9220, Aalborg, Denmark
| | - Jenny Tigerholm
- Center of Neuroplasticity and Pain, SMI®, Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7D3, 9220, Aalborg, Denmark.
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From Perception Threshold to Ion Channels-A Computational Study. Biophys J 2019; 117:281-295. [PMID: 31255293 DOI: 10.1016/j.bpj.2019.04.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 02/20/2019] [Accepted: 04/22/2019] [Indexed: 01/24/2023] Open
Abstract
Small-surface-area electrodes have successfully been used to preferentially activate cutaneous nociceptors, unlike conventional large area-electrodes, which preferentially activate large non-nociceptor fibers. Assessments of the strength-duration relationship, threshold electrotonus, and slowly increasing pulse forms have displayed different perception thresholds between large and small surface electrodes, which may indicate different excitability properties of the activated cutaneous nerves. In this study, the origin of the differences in perception thresholds between the two electrodes was investigated. It was hypothesized that different perception thresholds could be explained by the varying distributions of voltage-gated ion channels and by morphological differences between peripheral nerve endings of small and large fibers. A two-part computational model was developed to study activation of peripheral nerve fibers by different cutaneous electrodes. The first part of the model was a finite-element model, which calculated the extracellular field delivered by the cutaneous electrodes. The second part of the model was a detailed multicompartment model of an Aδ-axon as well as an Aβ-axon. The axon models included a wide range of voltage-gated ion channels: NaTTXs, NaTTXr, Nap, Kdr, KM, KA, and HCN channel. The computational model reproduced the experimentally assessed perception thresholds for the three protocols, the strength-duration relationship, the threshold electrotonus, and the slowly increasing pulse forms. The results support the hypothesis that voltage-gated ion channel distributions and morphology differences between small and large fibers were sufficient to explain the difference in perception thresholds between the two electrodes. In conclusion, assessments of perception thresholds using the three protocols may be an indirect measurement of the membrane excitability, and computational models may have the possibility to link voltage-gated ion channel activation to perception threshold measurements.
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Sauerstein K, Liebelt J, Namer B, Schmidt R, Rukwied R, Schmelz M. Low-Frequency Stimulation of Silent Nociceptors Induces Secondary Mechanical Hyperalgesia in Human Skin. Neuroscience 2018; 387:4-12. [DOI: 10.1016/j.neuroscience.2018.03.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 01/25/2018] [Accepted: 03/06/2018] [Indexed: 01/29/2023]
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Namer B, Ørstavik K, Schmidt R, Mair N, Kleggetveit IP, Zeidler M, Martha T, Jorum E, Schmelz M, Kalpachidou T, Kress M, Langeslag M. Changes in Ionic Conductance Signature of Nociceptive Neurons Underlying Fabry Disease Phenotype. Front Neurol 2017; 8:335. [PMID: 28769867 PMCID: PMC5510289 DOI: 10.3389/fneur.2017.00335] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 06/27/2017] [Indexed: 12/29/2022] Open
Abstract
The first symptom arising in many Fabry patients is neuropathic pain due to changes in small myelinated and unmyelinated fibers in the periphery, which is subsequently followed by a loss of sensory perception. Here we studied changes in the peripheral nervous system of Fabry patients and a Fabry mouse model induced by deletion of α-galactosidase A (Gla-/0). The skin innervation of Gla-/0 mice resembles that of the human Fabry patients. In Fabry diseased humans and Gla-/0 mice, we observed similar sensory abnormalities, which were also observed in nerve fiber recordings in both patients and mice. Electrophysiological recordings of cultured Gla-/0 nociceptors revealed that the conductance of voltage-gated Na+ and Ca2+ currents was decreased in Gla-/0 nociceptors, whereas the activation of voltage-gated K+ currents was at more depolarized potentials. Conclusively, we have observed that reduced sensory perception due to small-fiber degeneration coincides with altered electrophysiological properties of sensory neurons.
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Affiliation(s)
- Barbara Namer
- Department of Physiology and Pathophysiology, University of Erlangen-Nuremberg, Erlangen, Germany.,Department of Anesthesiology, Heidelberg University, Mannheim, Germany
| | - Kirstin Ørstavik
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital Rikshospitalet, Oslo, Norway
| | - Roland Schmidt
- Department of Clinical Neurophysiology, Uppsala University Hospital, Uppsala, Sweden
| | - Norbert Mair
- Department of Physiology and Medical Physics, Division of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Inge Petter Kleggetveit
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital Rikshospitalet, Oslo, Norway
| | - Maximillian Zeidler
- Department of Physiology and Medical Physics, Division of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Theresa Martha
- Department of Physiology and Medical Physics, Division of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Ellen Jorum
- Department of Anesthesiology, Heidelberg University, Mannheim, Germany.,Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Martin Schmelz
- Department of Anesthesiology, Heidelberg University, Mannheim, Germany
| | - Theodora Kalpachidou
- Department of Physiology and Medical Physics, Division of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Michaela Kress
- Department of Physiology and Medical Physics, Division of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Michiel Langeslag
- Department of Physiology and Medical Physics, Division of Physiology, Medical University of Innsbruck, Innsbruck, Austria
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14
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Z'Graggen WJ, Solà R, Graf NE, Serra J, Bostock H. Sensitivity to ischaemia of single sympathetic nerve fibres innervating the dorsum of the human foot. J Physiol 2017; 595:4467-4473. [PMID: 28378458 DOI: 10.1113/jp274324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 03/30/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Changes in nerve conduction velocity following an impulse (i.e. velocity recovery cycles) reflect after-potentials, and can provide an indication of altered nerve membrane properties. This study used microneurography to assess the effects of ischaemia on single human sympathetic fibres innervating the dorsum of the foot. It was found that velocity recovery cycles can distinguish whether a sympathetic nerve fibre is depolarized or not. The method may be used to detect membrane depolarization of sympathetic nerve fibres in human patients when autonomic neuropathy is suspected. ABSTRACT The aim of this study was to determine whether velocity recovery cycles (VRCs) could detect the effects of ischaemia on sympathetic nerve fibres. VRCs of human sympathetic nerve fibres of the superficial peroneal nerve innervating the dorsum of the foot were recorded by microneurography in seven healthy volunteers. Sympathetic nerve fibres were identified by studying their response to manoeuvres increasing sympathetic outflow and by measuring activity-dependent slowing at 2 Hz stimulation. VRCs were assessed at rest, during 30 min of induced limb ischaemia and during 20 min of recovery after ischaemia. From each VRC was measured the relative refractory period (RRP), the supernormality and the time to peak supernormality (SN@). During ischaemia, RRP increased from the baseline value of 37.4 ± 8.7 ms (mean ± SEM) to 67.1 ± 12.1 ms (P < 0.01) and SN@ increased from 68.6 ± 9.8 ms to 133.8 ± 11.0 ms (P < 0.005). The difference between SN@ and RRP separated ischaemic from non-ischaemic sympathetic nerve fibres. It is concluded that these sympathetic nerve fibres are sensitive to ischaemia, and that VRCs provide a method to study changes of axonal membrane potential of human sympathetic nerve fibres in vivo.
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Affiliation(s)
- W J Z'Graggen
- Department of Neurosurgery, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland.,Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - R Solà
- Neuroscience Technologies, Barcelona, Spain
| | - N E Graf
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - J Serra
- Neuroscience Technologies, Barcelona, Spain
| | - H Bostock
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, London, UK
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15
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Kleggetveit IP, Schmidt R, Namer B, Salter H, Helås T, Schmelz M, Jørum E. Pathological nociceptors in two patients with erythromelalgia-like symptoms and rare genetic Nav 1.9 variants. Brain Behav 2016; 6:e00528. [PMID: 27781142 PMCID: PMC5064340 DOI: 10.1002/brb3.528] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 06/02/2016] [Accepted: 06/05/2016] [Indexed: 01/03/2023] Open
Abstract
INTRODUCTION The sodium channel Nav 1.9 is expressed in peripheral nociceptors and has recently been linked to human pain conditions, but the exact role of Nav 1.9 for human nociceptor excitability is still unclear. METHODS C-nociceptors from two patients with late onset of erythromelalgia-like pain, signs of small fiber neuropathy, and rare genetic variants of Nav 1.9 (N1169S, I1293V) were assessed by microneurography. RESULTS Compared with patients with comparable pain phenotypes (erythromelalgia-like pain without Nav-mutations and painful polyneuropathy), there was a tendency toward more activity-dependent slowing of conduction velocity in mechanoinsensitive C-nociceptors. Hyperexcitability to heating and electrical stimulation were seen in some nociceptors, and other unspecific signs of increased excitability, including spontaneous activity and mechanical sensitization, were also observed. CONCLUSIONS Although the functional roles of these genetic variants are still unknown, the microneurography findings may be compatible with increased C-nociceptor excitability based on increased Nav 1.9 function.
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Affiliation(s)
- Inge P. Kleggetveit
- Section of Clinical NeurophysiologyDepartment of NeurologyOslo University Hospital‐RikshospitaletOsloNorway
| | - Roland Schmidt
- Department of Clinical NeurophysiologyUppsala UniversityUppsalaSweden
| | - Barbara Namer
- Institute of Physiology and PathophysiologyFriedrich‐Alexander‐Universität Erlangen‐NürnbergErlangenGermany
| | - Hugh Salter
- AstraZeneca Translational Science CentreDepartment of Clinical NeuroscienceKarolinska InstitutetSolnaSweden
| | - Tormod Helås
- Section of Clinical NeurophysiologyDepartment of NeurologyOslo University Hospital‐RikshospitaletOsloNorway
| | - Martin Schmelz
- Department of Anesthesiology MannheimHeidelberg UniversityMannheimGermany
| | - Ellen Jørum
- Section of Clinical NeurophysiologyDepartment of NeurologyOslo University Hospital‐RikshospitaletOsloNorway
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16
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Kist AM, Sagafos D, Rush AM, Neacsu C, Eberhardt E, Schmidt R, Lunden LK, Ørstavik K, Kaluza L, Meents J, Zhang Z, Carr TH, Salter H, Malinowsky D, Wollberg P, Krupp J, Kleggetveit IP, Schmelz M, Jørum E, Lampert A, Namer B. SCN10A Mutation in a Patient with Erythromelalgia Enhances C-Fiber Activity Dependent Slowing. PLoS One 2016; 11:e0161789. [PMID: 27598514 PMCID: PMC5012686 DOI: 10.1371/journal.pone.0161789] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/11/2016] [Indexed: 11/18/2022] Open
Abstract
Gain-of-function mutations in the tetrodotoxin (TTX) sensitive voltage-gated sodium channel (Nav) Nav1.7 have been identified as a key mechanism underlying chronic pain in inherited erythromelalgia. Mutations in TTX resistant channels, such as Nav1.8 or Nav1.9, were recently connected with inherited chronic pain syndromes. Here, we investigated the effects of the p.M650K mutation in Nav1.8 in a 53 year old patient with erythromelalgia by microneurography and patch-clamp techniques. Recordings of the patient’s peripheral nerve fibers showed increased activity dependent slowing (ADS) in CMi and less spontaneous firing compared to a control group of erythromelalgia patients without Nav mutations. To evaluate the impact of the p.M650K mutation on neuronal firing and channel gating, we performed current and voltage-clamp recordings on transfected sensory neurons (DRGs) and neuroblastoma cells. The p.M650K mutation shifted steady-state fast inactivation of Nav1.8 to more hyperpolarized potentials and did not significantly alter any other tested gating behaviors. The AP half-width was significantly broader and the stimulated action potential firing rate was reduced for M650K transfected DRGs compared to WT. We discuss the potential link between enhanced steady state fast inactivation, broader action potential width and the potential physiological consequences.
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Affiliation(s)
- Andreas M. Kist
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Dagrun Sagafos
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital -Rikshospitalet, Oslo, Norway
| | | | - Cristian Neacsu
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Esther Eberhardt
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- Department of Anesthesiology, Friedrich-Alexander-Universität Erlangen-Nuremberg, Erlangen, Germany
| | - Roland Schmidt
- Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Uppsala, Sweden
| | - Lars Kristian Lunden
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital -Rikshospitalet, Oslo, Norway
| | - Kristin Ørstavik
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital -Rikshospitalet, Oslo, Norway
| | - Luisa Kaluza
- Institute of Physiology, RWTH Aachen University Hospital, Aachen, Germany
| | - Jannis Meents
- Institute of Physiology, RWTH Aachen University Hospital, Aachen, Germany
| | | | | | | | | | | | | | - Inge Petter Kleggetveit
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital -Rikshospitalet, Oslo, Norway
| | - Martin Schmelz
- Department of Anesthesiology Mannheim, Heidelberg University, Mannheim, Germany
| | - Ellen Jørum
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital -Rikshospitalet, Oslo, Norway
- * E-mail: (EJ); (AL); (BN)
| | - Angelika Lampert
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- Institute of Physiology, RWTH Aachen University Hospital, Aachen, Germany
- * E-mail: (EJ); (AL); (BN)
| | - Barbara Namer
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- Department of Anesthesiology Mannheim, Heidelberg University, Mannheim, Germany
- * E-mail: (EJ); (AL); (BN)
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17
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Hoffmann T, Kistner K, Nassar M, Reeh PW, Weidner C. Use dependence of peripheral nociceptive conduction in the absence of tetrodotoxin-resistant sodium channel subtypes. J Physiol 2016; 594:5529-41. [PMID: 27105013 DOI: 10.1113/jp272082] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 04/11/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS This study examines conduction in peripheral nerves and its use dependence in tetrodotoxin-resistant (TTXr) sodium channel (Nav 1.8, Nav 1.9) knockout and wildtype animals. We observed use-dependent decreases of single fibre and compound action potential amplitude in peripheral mouse C-fibres (wildtype). This matches the previously published hypothesis that increased Na/K-pump activity is not the underlying mechanism for use-dependent changes of neural conduction. Knocking out TTXr sodium channels influences use-dependent changes of conductive properties (action potential amplitude, latency, conduction safety) in the order Nav 1.8 KO > Nav 1.9KO > wildtype. This is most likely explained by different subsets of presumably (relatively) Nav 1.7-rich conducting fibres in knockout animals as compared to wildtypes, in combination with reduced per-pulse sodium influx. ABSTRACT Use dependency of peripheral nerves, especially of nociceptors, correlates with receptive properties. Slow inactivation of voltage-gated sodium channels has been discussed to be the underlying mechanism - pointing to a receptive class-related difference of sodium channel equipment. Using electrophysiological recordings of single unmyelinated cutaneous fibres and their compound action potential (AP), we evaluated use-dependent changes in mouse peripheral nerves, and the contribution of the tetrodotoxin-resistant (TTXr) sodium channels Nav 1.8 and Nav 1.9 to these changes. Nerve fibres were electrically stimulated using single or double pulses at 2 Hz. Use-dependent changes of latency, AP amplitude, and duration as well as the fibres' ability to follow the stimulus were evaluated. AP amplitudes substantially diminished in used fibres from C57BL/6 but increased in Nav 1.8 knockout (KO) mice, with Nav 1.9 KO in between. Activity-induced latency slowing was in contrast the most pronounced in Nav 1.8 KOs and the least in wildtype mice. The genotype was also predictive of how long fibres could follow the double pulsed stimulus with wildtype fibres blocking first and Nav 1.8 KO fibres enduring the longest. In contrast, changes in spike duration were less pronounced and displayed no significant tendency. Thus, all major measures of peripheral nerve accommodation (amplitude, latency and durability) depended on genotype. All use-dependent changes appeared in the order NaV 1.8 KO > NaV 1.9 KO > wildtype, which is most likely explained by the relative contribution of Nav 1.7 varying in the same order and the amounts of per-pulse sodium influx expected in the opposite order.
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Affiliation(s)
- Tal Hoffmann
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Erlangen, Germany.
| | - Katrin Kistner
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Erlangen, Germany
| | | | - Peter W Reeh
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Christian Weidner
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Erlangen, Germany
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18
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Specific changes in conduction velocity recovery cycles of single nociceptors in a patient with erythromelalgia with the I848T gain-of-function mutation of Nav1.7. Pain 2016; 156:1637-1646. [PMID: 25993546 DOI: 10.1097/j.pain.0000000000000229] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Seven patients diagnosed with erythromelalgia (EM) were investigated by microneurography to record from unmyelinated nerve fibers in the peroneal nerve. Two patients had characterized variants of sodium channel Nav1.7 (I848T, I228M), whereas no mutations of coding regions of Navs were found in 5 patients with EM. Irrespective of Nav1.7 mutations, more than 50% of the silent nociceptors in the patients with EM showed spontaneous activity. In the patient with mutation I848T, all nociceptors, but not sympathetic efferents, displayed enhanced early subnormal conduction in the velocity recovery cycles and the expected late subnormality was reversed to supranormal conduction. The larger hyperpolarizing shift of activation might explain the difference to the I228M mutation. Sympathetic fibers that lack Nav1.8 did not show supranormal conduction in the patient carrying the I848T mutation, confirming in human subjects that the presence of Nav1.8 crucially modulates conduction in cells expressing EM mutant channels. The characteristic pattern of changes in conduction velocity observed in the patient with the I848T gain-of function mutation in Nav1.7 could be explained by axonal depolarization and concomitant inactivation of Nav1.7. If this were true, activity-dependent hyperpolarization would reverse inactivation of Nav1.7 and account for the supranormal CV. This mechanism might explain normal pain thresholds under resting conditions.
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