1
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Wang S, Lam SS, Aguilar A, Anakwe S, Barahona K, Haider H, Hunyadi O, Jain K, Kolodziejski D, Lal A, Li M, MacKenzie F, Miller J, Nardin O, Nguyen E, Pappu J, Rodriguez M, Lin JW. Inhibitory modulation of action potentials in crayfish motor axons by fluoxetine. Synapse 2024; 78:e22304. [PMID: 38896000 DOI: 10.1002/syn.22304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 05/07/2024] [Accepted: 06/02/2024] [Indexed: 06/21/2024]
Abstract
The goal of this report is to explore how K2P channels modulate axonal excitability by using the crayfish ventral superficial flexor preparation. This preparation allows for simultaneous recording of motor nerve extracellular action potentials (eAP) and intracellular excitatory junctional potential (EJP) from a muscle fiber. Previous pharmacological studies have demonstrated the presence of K2P-like channels in crayfish. Fluoxetine (50 µM) was used to block K2P channels in this study. The blocker caused a gradual decline, and eventually complete block, of motor axon action potentials. At an intermediate stage of the block, when the peak-to-peak amplitude of eAP decreased to ∼60%-80% of the control value, the amplitude of the initial positive component of eAP declined at a faster rate than that of the negative peak representing sodium influx. Furthermore, the second positive peak following this sodium influx, which corresponds to the after-hyperpolarizing phase of intracellularly recorded action potentials (iAP), became larger during the intermediate stage of eAP block. Finally, EJP recorded simultaneously with eAP showed no change in amplitude, but did show a significant increase in synaptic delay. These changes in eAP shape and EJP delay are interpreted as the consequence of depolarized resting membrane potential after K2P channel block. In addition to providing insights to possible functions of K2P channels in unmyelinated axons, results presented here also serve as an example of how changes in eAP shape contain information that can be used to infer alterations in intracellular events. This type of eAP-iAP cross-inference is valuable for gaining mechanistic insights here and may also be applicable to other model systems.
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Affiliation(s)
- Selene Wang
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Si Seng Lam
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Anisah Aguilar
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Stephanie Anakwe
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | | | - Hani Haider
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Olivia Hunyadi
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Kaahini Jain
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | | | - Anindita Lal
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Man Li
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Frank MacKenzie
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - John Miller
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Oliviero Nardin
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Emily Nguyen
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Jaii Pappu
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Melissa Rodriguez
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Jen-Wei Lin
- Department of Biology, Boston University, Boston, Massachusetts, USA
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2
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Choi D, Goodwin G, Stevens EB, Soliman N, Namer B, Denk F. Spontaneous activity in peripheral sensory nerves: a systematic review. Pain 2024; 165:983-996. [PMID: 37991272 PMCID: PMC11017746 DOI: 10.1097/j.pain.0000000000003115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/29/2023] [Accepted: 09/23/2023] [Indexed: 11/23/2023]
Abstract
ABSTRACT In the peripheral nervous system, spontaneous activity in sensory neurons is considered to be one of the 2 main drivers of chronic pain states, alongside neuronal sensitization. Despite this, the precise nature and timing of this spontaneous activity in neuropathic pain is not well-established. Here, we have performed a systematic search and data extraction of existing electrophysiological literature to shed light on which fibre types have been shown to maintain spontaneous activity and over what time frame. We examined both in vivo recordings of preclinical models of neuropathic pain, as well as microneurography recordings in humans. Our analyses reveal that there is broad agreement on the presence of spontaneous activity in neuropathic pain conditions, even months after injury or years after onset of neuropathic symptoms in humans. However, because of the highly specialised nature of the electrophysiological methods used to measure spontaneous activity, there is also a high degree of variability and uncertainty around these results. Specifically, there are very few directly controlled experiments, with less directly comparable data between human and animals. Given that spontaneous peripheral neuron activity is considered to be a key mechanistic feature of chronic pain conditions, it may be beneficial to conduct further experiments in this space.
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Affiliation(s)
- Dongchan Choi
- Wolfson Centre for Age-Related Diseases, Guy's Campus, King's College London, London, United Kingdom
| | - George Goodwin
- Wolfson Centre for Age-Related Diseases, Guy's Campus, King's College London, London, United Kingdom
| | - Edward B. Stevens
- Metrion Biosciences Ltd, Building 2 Granta Centre, Granta Park, Cambridge, United Kingdom
| | - Nadia Soliman
- Imperial College London, Pain Research Group, Chelsea and Westminster Hospital, London, United Kingdom
| | - Barbara Namer
- Research Group Neuroscience of the Interdisziplinary Center for Clinical Research, University Hospital of the RWTH Aachen, Aachen, Germany
- Institute for Physiology, University Hospital of the RWTH Aachen, Aachen, Germany
| | - Franziska Denk
- Wolfson Centre for Age-Related Diseases, Guy's Campus, King's College London, London, United Kingdom
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3
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Krotov V, Kopach O. Nerve Preparation and Recordings for Pharmacological Tests of Sensory and Nociceptive Fiber Conduction Ex Vivo. Bio Protoc 2024; 14:e4969. [PMID: 38618174 PMCID: PMC11006801 DOI: 10.21769/bioprotoc.4969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 02/27/2024] [Accepted: 02/28/2024] [Indexed: 04/16/2024] Open
Abstract
Measuring signal propagation through nerves is a classical electrophysiological technique established decades ago to evaluate sensory and motor functions in the nervous system. The whole-nerve preparation provides a valuable model to investigate nerve function ex vivo; however, it requires specific knowledge to ensure successful and stable measurements. Although the methodology for sciatic nerve recordings has long existed, a method for reliable and long-lasting recordings from myelinated and non-myelinated (nociceptive) fibers still needs to be adapted for pharmacological testing. This protocol takes benefits from epineurium sheath removal for pharmacological tests and provides a detailed description of how to make accurate nerve preparations, from the dissection and handling of nerves to epineurium cleaning, fabrication of adaptable suction electrodes for appropriate fiber stimulation and recordings, setting of electrophysiological protocols for compound action potential (CAP) recordings to distinguish between myelinated and non-myelinated (nociceptive) fibers, and finally to the analysis of the datasets of CAP components. We also demonstrate the feasibility of CAP recordings from individual branches in epineurium-free nerve preparations and provide clues to help retain nerve viability and maintain stable recordings over time. Although a sciatic nerve preparation was used here, the methodology can be applied to other nerve-type preparations. Key features • Detailed and simplified protocol for peripheral nerve preparation for recording sensory inputs ex vivo. • Recordings from myelinated and non-myelinated (nociceptive) fibers can be performed hours after nerve preparation. • The protocol involves the epineurium removal to facilitate drug permeability into nerve tissue for pharmacological tests. • The protocol allows physiological and pathological studies (pain/chronic pain conditions).
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Affiliation(s)
- Volodymyr Krotov
- Bogomoletz Institute of Physiology, Kyiv, Ukraine
- University College London, London, UK
| | - Olga Kopach
- Queen Square Institute of Neurology, University College London, London, UK
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4
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Koh RGL, Zariffa J, Jabban L, Yen SC, Donaldson N, Metcalfe BW. Tutorial: A guide to techniques for analysing recordings from the peripheral nervous system. J Neural Eng 2022; 19. [PMID: 35772397 DOI: 10.1088/1741-2552/ac7d74] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 06/30/2022] [Indexed: 11/11/2022]
Abstract
The nervous system, through a combination of conscious and automatic processes, enables the regulation of the body and its interactions with the environment. The peripheral nervous system is an excellent target for technologies that seek to modulate, restore or enhance these abilities as it carries sensory and motor information that most directly relates to a target organ or function. However, many applications require a combination of both an effective peripheral nerve interface and effective signal processing techniques to provide selective and stable recordings. While there are many reviews on the design of peripheral nerve interfaces, reviews of data analysis techniques and translational considerations are limited. Thus, this tutorial aims to support new and existing researchers in the understanding of the general guiding principles, and introduces a taxonomy for electrode configurations, techniques and translational models to consider.
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Affiliation(s)
- Ryan G L Koh
- IBBME, University of Toronto, Rosebrugh Bldg, 164 College St Room 407, Toronto, Ontario, M5S 3G9, CANADA
| | - Jose Zariffa
- Research, Toronto Rehabilitation Institute - University Health Network, 550 University Ave, #12-102, Toronto, Ontario, M5G 2A2, CANADA
| | - Leen Jabban
- Electronic and Electrical Engineering, University of Bath, Electronic and Electrical Engineering, Claverton Down, Bath, Bath, BA2 7AY, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Shih-Cheng Yen
- Engineering Design and Innovation Centre, National University of Singapore, 21 Lower Kent Ridge Road, Singapore, 119077, SINGAPORE
| | - Nick Donaldson
- Medical Physics and Bioengineering, University College London, Gower Street, London, WC1E 6BT, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Benjamin W Metcalfe
- Electronics & Electrical Engineering, University of Bath, Claverton Down, Bath, Somerset, BA2 7JY, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
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5
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Slow touch in non-human species: translational research into the C-tactile (CT) afferent system. Curr Opin Behav Sci 2022. [DOI: 10.1016/j.cobeha.2021.10.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Abstract
Neuroelectrophysiology is an old science, dating to the 18th century when electrical activity in nerves was discovered. Such discoveries have led to a variety of neurophysiological techniques, ranging from basic neuroscience to clinical applications. These clinical applications allow assessment of complex neurological functions such as (but not limited to) sensory perception (vision, hearing, somatosensory function), and muscle function. The ability to use similar techniques in both humans and animal models increases the ability to perform mechanistic research to investigate neurological problems. Good animal to human homology of many neurophysiological systems facilitates interpretation of data to provide cause-effect linkages to epidemiological findings. Mechanistic cellular research to screen for toxicity often includes gaps between cellular and whole animal/person neurophysiological changes, preventing understanding of the complete function of the nervous system. Building Adverse Outcome Pathways (AOPs) will allow us to begin to identify brain regions, timelines, neurotransmitters, etc. that may be Key Events (KE) in the Adverse Outcomes (AO). This requires an integrated strategy, from in vitro to in vivo (and hypothesis generation, testing, revision). Scientists need to determine intermediate levels of nervous system organization that are related to an AO and work both upstream and downstream using mechanistic approaches. Possibly more than any other organ, the brain will require networks of pathways/AOPs to allow sufficient predictive accuracy. Advancements in neurobiological techniques should be incorporated into these AOP-base neurotoxicological assessments, including interactions between many regions of the brain simultaneously. Coupled with advancements in optogenetic manipulation, complex functions of the nervous system (such as acquisition, attention, sensory perception, etc.) can be examined in real time. The integration of neurophysiological changes with changes in gene/protein expression can begin to provide the mechanistic underpinnings for biological changes. Establishment of linkages between changes in cellular physiology and those at the level of the AO will allow construction of biological pathways (AOPs) and allow development of higher throughput assays to test for changes to critical physiological circuits. To allow mechanistic/predictive toxicology of the nervous system to be protective of human populations, neuroelectrophysiology has a critical role in our future.
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Affiliation(s)
- David W Herr
- Neurological and Endocrine Toxicology Branch, Public Health and Integrated Toxicology Division, CPHEA/ORD, U.S. Environmental Protection Agency, Washington, NC, United States
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Kraus RL, Zhao F, Pall PS, Zhou D, Vardigan JD, Danziger A, Li Y, Daley C, Ballard JE, Clements MK, Klein RM, Holahan MA, Greshock TJ, Kim RM, Layton ME, Burgey CS, Serra J, Henze DA, Houghton AK. Na v1.7 target modulation and efficacy can be measured in nonhuman primate assays. Sci Transl Med 2021; 13:13/594/eaay1050. [PMID: 34011626 DOI: 10.1126/scitranslmed.aay1050] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 06/03/2020] [Accepted: 02/20/2021] [Indexed: 12/13/2022]
Abstract
Humans with loss-of-function mutations in the Nav1.7 channel gene (SCN9A) show profound insensitivity to pain, whereas those with gain-of-function mutations can have inherited pain syndromes. Therefore, inhibition of the Nav1.7 channel with a small molecule has been considered a promising approach for the treatment of various human pain conditions. To date, clinical studies conducted using selective Nav1.7 inhibitors have not provided analgesic efficacy sufficient to warrant further investment. Clinical studies to date used multiples of in vitro IC50 values derived from electrophysiological studies to calculate anticipated human doses. To increase the chance of clinical success, we developed rhesus macaque models of action potential propagation, nociception, and olfaction, to measure Nav1.7 target modulation in vivo. The potent and selective Nav1.7 inhibitors SSCI-1 and SSCI-2 dose-dependently blocked C-fiber nociceptor conduction in microneurography studies and inhibited withdrawal responses to noxious heat in rhesus monkeys. Pharmacological Nav1.7 inhibition also reduced odor-induced activation of the olfactory bulb (OB), measured by functional magnetic resonance imaging (fMRI) studies consistent with the anosmia reported in Nav1.7 loss-of-function patients. These data demonstrate that it is possible to measure Nav1.7 target modulation in rhesus macaques and determine the plasma concentration required to produce a predetermined level of inhibition. The calculated plasma concentration for preclinical efficacy could be used to guide human efficacious exposure estimates. Given the translatable nature of the assays used, it is anticipated that they can be also used in phase 1 clinical studies to measure target modulation and aid in the interpretation of phase 1 clinical data.
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Affiliation(s)
- Richard L Kraus
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA.
| | - Fuqiang Zhao
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Parul S Pall
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Dan Zhou
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Joshua D Vardigan
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Andrew Danziger
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Yuxing Li
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Christopher Daley
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Jeanine E Ballard
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Michelle K Clements
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Rebecca M Klein
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Marie A Holahan
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Thomas J Greshock
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Ronald M Kim
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Mark E Layton
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Christopher S Burgey
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Jordi Serra
- Department of Clinical Neurophysiology, Ruskin Wing, King's College Hospital, Denmark Hill, London SE5 9RS, UK
| | - Darrell A Henze
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
| | - Andrea K Houghton
- Merck & Co. Inc., WP-14, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486, USA
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8
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Fisher AS, Lanigan MT, Upton N, Lione LA. Preclinical Neuropathic Pain Assessment; the Importance of Translatability and Bidirectional Research. Front Pharmacol 2021; 11:614990. [PMID: 33628181 PMCID: PMC7897667 DOI: 10.3389/fphar.2020.614990] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 12/10/2020] [Indexed: 02/04/2023] Open
Abstract
For patients suffering with chronic neuropathic pain the need for suitable novel therapies is imperative. Over recent years a contributing factor for the lack of development of new analgesics for neuropathic pain has been the mismatch of primary neuropathic pain assessment endpoints in preclinical vs. clinical trials. Despite continuous forward translation failures across diverse mechanisms, reflexive quantitative sensory testing remains the primary assessment endpoint for neuropathic pain and analgesia in animals. Restricting preclinical evaluation of pain and analgesia to exclusively reflexive outcomes is over simplified and can be argued not clinically relevant due to the continued lack of forward translation and failures in the clinic. The key to developing new analgesic treatments for neuropathic pain therefore lies in the development of clinically relevant endpoints that can translate preclinical animal results to human clinical trials. In this review we discuss this mismatch of primary neuropathic pain assessment endpoints, together with clinical and preclinical evidence that supports how bidirectional research is helping to validate new clinically relevant neuropathic pain assessment endpoints. Ethological behavioral endpoints such as burrowing and facial grimacing and objective measures such as electroencephalography provide improved translatability potential together with currently used quantitative sensory testing endpoints. By tailoring objective and subjective measures of neuropathic pain the translatability of new medicines for patients suffering with neuropathic pain will hopefully be improved.
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Affiliation(s)
- Amy S. Fisher
- Transpharmation Ltd., The London Bioscience Innovation Centre, London, United Kingdom
| | - Michael T. Lanigan
- Transpharmation Ltd., The London Bioscience Innovation Centre, London, United Kingdom
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom
| | - Neil Upton
- Transpharmation Ltd., The London Bioscience Innovation Centre, London, United Kingdom
| | - Lisa A. Lione
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom
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9
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Bruna J, Alberti P, Calls-Cobos A, Caillaud M, Damaj MI, Navarro X. Methods for in vivo studies in rodents of chemotherapy induced peripheral neuropathy. Exp Neurol 2020; 325:113154. [PMID: 31837318 PMCID: PMC7105293 DOI: 10.1016/j.expneurol.2019.113154] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 12/07/2019] [Accepted: 12/10/2019] [Indexed: 12/15/2022]
Abstract
Peripheral neuropathy is one of the most common, dose limiting, and long-lasting disabling adverse events of chemotherapy treatment. Unfortunately, no treatment has proven efficacy to prevent this adverse effect in patients or improve the nerve regeneration, once it is established. Experimental models, particularly using rats and mice, are useful to investigate the mechanisms related to axonal or neuronal degeneration and target loss of function induced by neurotoxic drugs, as well as to test new strategies to prevent the development of neuropathy and to improve functional restitution. Therefore, objective and reliable methods should be applied for the assessment of function and innervation in adequately designed in vivo studies of CIPN, taking into account the impact of age, sex and species/strains features. This review gives an overview of the most useful methods to assess sensory, motor and autonomic functions, electrophysiological and morphological tests in rodent models of peripheral neuropathy, focused on CIPN. We include as well a proposal of protocols that may improve the quality and comparability of studies undertaken in different laboratories. It is recommended to apply more than one functional method for each type of function, and to perform parallel morphological studies in the same targets and models.
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Affiliation(s)
- Jordi Bruna
- Unit of Neuro-Oncology, Hospital Universitari de Bellvitge, Institut Català d'Oncologia L'Hospitalet, IDIBELL, Hospitalet de Llobregat, Barcelona, Spain; Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain
| | - Paola Alberti
- Experimental Neurology Unit, School of Medicine and Surgery, University Milano Bicocca, Monza, Italy; NeuroMI (Milan Center for Neuroscience), Milan, Italy
| | - Aina Calls-Cobos
- Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain
| | - Martial Caillaud
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA
| | - M Imad Damaj
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA
| | - Xavier Navarro
- Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain.
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10
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Raspopovic S, Cimolato A, Panarese A, Vallone F, Del Valle J, Micera S, Navarro X. Neural signal recording and processing in somatic neuroprosthetic applications. A review. J Neurosci Methods 2020; 337:108653. [PMID: 32114143 DOI: 10.1016/j.jneumeth.2020.108653] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 11/30/2019] [Accepted: 02/26/2020] [Indexed: 12/11/2022]
Abstract
Neurointerfaces have acquired major relevance as both rehabilitative and therapeutic tools for patients with spinal cord injury, limb amputations and other neural disorders. Bidirectional neural interfaces are a key component for the functional control of neuroprosthetic devices. The two main neuroprosthetic applications of interfaces with the peripheral nervous system (PNS) are: the refined control of artificial prostheses with sensory neural feedback, and functional electrical stimulation (FES) systems attempting to generate motor or visceral responses in paralyzed organs. The results obtained in experimental and clinical studies with both, extraneural and intraneural electrodes are very promising in terms of the achieved functionality for the neural stimulation mode. However, the results of neural recordings with peripheral nerve interfaces are more limited. In this paper we review the different existing approaches for PNS signals recording, denoising, processing and classification, enabling their use for bidirectional interfaces. PNS recordings can provide three types of signals: i) population activity signals recorded by using extraneural electrodes placed on the outer surface of the nerve, which carry information about cumulative nerve activity; ii) spike activity signals recorded with intraneural electrodes placed inside the nerve, which carry information about the electrical activity of a set of individual nerve fibers; and iii) hybrid signals, which contain both spiking and cumulative signals. Finally, we also point out some of the main limitations, which are hampering clinical translation of neural decoding, and indicate possible solutions for improvement.
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Affiliation(s)
- Stanisa Raspopovic
- Neuroengineering Lab, Department of Health Sciences and Technology, Institute for Robotics and Intelligent Systems, ETH Zürich, 8092, Zürich, Switzerland
| | - Andrea Cimolato
- Neuroengineering Lab, Department of Health Sciences and Technology, Institute for Robotics and Intelligent Systems, ETH Zürich, 8092, Zürich, Switzerland; NEARLab - Neuroengineering and Medical Robotics Laboratory, DEIB Department of Electronics, Information and Bioengineering, Politecnico Di Milano, 20133, Milano, Italy; IIT Central Research Labs Genova, Istituto Italiano Tecnologia, 16163, Genova, Italy
| | | | - Fabio Vallone
- The BioRobotics Institute, Scuola Superiore Sant'Anna, I-56127, Pisa, Italy
| | - Jaume Del Valle
- Institute of Neurosciences and Department of Cell Biology, Physiology and Immunology, Universitat Autònoma De Barcelona, CIBERNED, 08193, Bellaterra, Spain
| | - Silvestro Micera
- The BioRobotics Institute, Scuola Superiore Sant'Anna, I-56127, Pisa, Italy; Translational Neural Engineering Laboratory, Center for Neuroprosthetics and Institute of Bioengineering, Ecole Polytechnique Federale De Lausanne, Lausanne, CH-1015, Switzerland.
| | - Xavier Navarro
- Institute of Neurosciences and Department of Cell Biology, Physiology and Immunology, Universitat Autònoma De Barcelona, CIBERNED, 08193, Bellaterra, Spain; Institut Guttmann De Neurorehabilitació, Badalona, Spain.
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11
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Abstract
The poor translational record of pain research has suggested to some observers that species differences in pain biology might be to blame. In this review, I consider the evidence for species similarity and differences in the pain research literature. Impressive feats of translation have been demonstrated in relation to certain genetic effects, social modulation of pain and pain memory. The degree to which pain biology in rodents predicts pain biology in humans has important implications both for evolutionary accounts of pain, but also the success of analgesic drug development going forward. This article is part of the Theo Murphy meeting issue 'Evolution of mechanisms and behaviour important for pain'.
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Affiliation(s)
- Jeffrey S Mogil
- Departments of Psychology and Anesthesia, McGill University, Montreal, Quebec, Canada H3A 1B1
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12
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Ackerley R, Watkins RH. Microneurography as a tool to study the function of individual C-fiber afferents in humans: responses from nociceptors, thermoreceptors, and mechanoreceptors. J Neurophysiol 2018; 120:2834-2846. [PMID: 30256737 DOI: 10.1152/jn.00109.2018] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The technique of microneurography-recording neural traffic from nerves in awake humans-has provided us with unrivaled insights into afferent and efferent processes in the peripheral nervous system for over 50 years. We review the use of microneurography to study single C-fiber afferents and provide an overview of the knowledge gained, with views to future investigations. C-fibers have slowly conducting, thin-diameter, unmyelinated axons and make up the majority of the fibers in peripheral nerves (~80%). With the use of microneurography in humans, C-fiber afferents have been differentiated into discrete subclasses that encode specific qualities of stimuli on the skin, and their functional roles have been investigated. Afferent somatosensory information provided by C-fibers underpins various positive and negative affective sensations from the periphery, including mechanical, thermal, and chemical pain (C-nociceptors), temperature (C-thermoreceptors), and positive affective aspects of touch (C-tactile afferents). Insights from microneurographic investigations have revealed the complexity of the C-fiber system, methods for delineating fundamental C-fiber populations in a translational manner, how C-fiber firing can be used to identify nerve deficits in pathological states, and how the responses from C-fibers may be modified to change sensory percepts, including decreasing pain. Understanding these processes may lead to future medical interventions to diagnose and treat C-fiber dysfunction. NEW & NOTEWORTHY The technique of microneurography allows us to directly investigate the functional roles of single C-fiber afferents in awake human beings. Here we outline and discuss the current field of C-fiber research on this heterogeneous population of afferents in healthy subjects, in pathological states, and from a translational perspective. We cover C-fibers encoding touch, temperature, and pain and provide perspectives on the future of C-fiber microneurography investigations in humans.
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Affiliation(s)
- Rochelle Ackerley
- Aix Marseille University, CNRS, LNSC (Laboratoire de Neurosciences Sensorielles et Cognitives - UMR 7260), Marseille, France.,Department of Physiology, University of Gothenburg , Gothenburg , Sweden
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Garcia-Perez E, Schönberger T, Sumalla M, Stierstorfer B, Solà R, Doods H, Serra J, Gorodetskaya N. Behavioural, morphological and electrophysiological assessment of the effects of type 2 diabetes mellitus on large and small nerve fibres in Zucker diabetic fatty, Zucker lean and Wistar rats. Eur J Pain 2018; 22:1457-1472. [DOI: 10.1002/ejp.1235] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/11/2018] [Indexed: 01/09/2023]
Affiliation(s)
| | - T. Schönberger
- Boehringer Ingelheim Pharma GmbH & Co. KG; Biberach an der Riss Germany
| | - M. Sumalla
- Neuroscience Technologies; Barcelona Spain
| | - B. Stierstorfer
- Boehringer Ingelheim Pharma GmbH & Co. KG; Biberach an der Riss Germany
| | - R. Solà
- Neuroscience Technologies; Barcelona Spain
| | - H. Doods
- Boehringer Ingelheim Pharma GmbH & Co. KG; Biberach an der Riss Germany
| | - J. Serra
- Neuroscience Technologies; Barcelona Spain
| | - N. Gorodetskaya
- Boehringer Ingelheim Pharma GmbH & Co. KG; Biberach an der Riss Germany
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Chen L, Ilham SJ, Guo T, Emadi S, Feng B. In vitro multichannel single-unit recordings of action potentials from mouse sciatic nerve. Biomed Phys Eng Express 2017; 3:045020. [PMID: 29568573 PMCID: PMC5858727 DOI: 10.1088/2057-1976/aa7efa] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Electrode arrays interfacing with peripheral nerves are essential for neuromodulation devices targeting peripheral organs to relieve symptoms. To modulate (i.e., single-unit recording and stimulating) individual peripheral nerve axons remains a technical challenge. Here, we report an in vitro setup to allow simultaneous single-unit recordings from multiple mouse sciatic nerve axons. The sciatic nerve (~30 mm) was harvested and transferred to a tissue chamber, the ~5mm distal end pulled into an adjacent recording chamber filled with paraffin oil. A custom-built multi-wire electrode array was used to interface with split fine nerve filaments. Single-unit action potentials were evoked by electrical stimulation and recorded from 186 axons, of which 49.5% were classed A-type with conduction velocities (CV) greater than 1 m/s and 50.5% were C-type (CV < 1 m/s). The single-unit recordings had no apparent bias towards A- or C-type axons, were robust and repeatable for over 60 minutes, and thus an ideal opportunity to assess different neuromodulation strategies targeting peripheral nerves. For instance, ultrasonic modulation of action potential transmission was assessed using the setup, indicating increased nerve conduction velocity following ultrasound stimulus. This setup can also be used to objectively assess the design of next-generation electrode arrays interfacing with peripheral nerves.
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Affiliation(s)
- L Chen
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
| | - S J Ilham
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
| | - T Guo
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
| | - S Emadi
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
| | - B Feng
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
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HCN2 ion channels: basic science opens up possibilities for therapeutic intervention in neuropathic pain. Biochem J 2016; 473:2717-36. [DOI: 10.1042/bcj20160287] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 05/18/2016] [Indexed: 01/22/2023]
Abstract
Nociception — the ability to detect painful stimuli — is an invaluable sense that warns against present or imminent damage. In patients with chronic pain, however, this warning signal persists in the absence of any genuine threat and affects all aspects of everyday life. Neuropathic pain, a form of chronic pain caused by damage to sensory nerves themselves, is dishearteningly refractory to drugs that may work in other types of pain and is a major unmet medical need begging for novel analgesics. Hyperpolarisation-activated cyclic nucleotide (HCN)-modulated ion channels are best known for their fundamental pacemaker role in the heart; here, we review data demonstrating that the HCN2 isoform acts in an analogous way as a ‘pacemaker for pain’, in that its activity in nociceptive neurons is critical for the maintenance of electrical activity and for the sensation of chronic pain in pathological pain states. Pharmacological block or genetic deletion of HCN2 in sensory neurons provides robust pain relief in a variety of animal models of inflammatory and neuropathic pain, without any effect on normal sensation of acute pain. We discuss the implications of these findings for our understanding of neuropathic pain pathogenesis, and we outline possible future opportunities for the development of efficacious and safe pharmacotherapies in a range of chronic pain syndromes.
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Behavioral and electrophysiological abnormalities in two rat models of antiretroviral drug-induced neuropathy. Pain 2015; 156:1729-1736. [DOI: 10.1097/j.pain.0000000000000205] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Microneurographic recording from unmyelinated nerve fibers in neurological disorders: An update. Clin Neurophysiol 2015; 126:437-45. [DOI: 10.1016/j.clinph.2014.10.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/25/2014] [Accepted: 10/06/2014] [Indexed: 12/14/2022]
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Gore RK, Choi Y, Bellamkonda R, English A. Functional recordings from awake, behaving rodents through a microchannel based regenerative neural interface. J Neural Eng 2015; 12:016017. [PMID: 25605627 DOI: 10.1088/1741-2560/12/1/016017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVE Neural interface technologies could provide controlling connections between the nervous system and external technologies, such as limb prosthetics. The recording of efferent, motor potentials is a critical requirement for a peripheral neural interface, as these signals represent the user-generated neural output intended to drive external devices. Our objective was to evaluate structural and functional neural regeneration through a microchannel neural interface and to characterize potentials recorded from electrodes placed within the microchannels in awake and behaving animals. APPROACH Female rats were implanted with muscle EMG electrodes and, following unilateral sciatic nerve transection, the cut nerve was repaired either across a microchannel neural interface or with end-to-end surgical repair. During a 13 week recovery period, direct muscle responses to nerve stimulation proximal to the transection were monitored weekly. In two rats repaired with the neural interface, four wire electrodes were embedded in the microchannels and recordings were obtained within microchannels during proximal stimulation experiments and treadmill locomotion. MAIN RESULTS In these proof-of-principle experiments, we found that axons from cut nerves were capable of functional reinnervation of distal muscle targets, whether regenerating through a microchannel device or after direct end-to-end repair. Discrete stimulation-evoked and volitional potentials were recorded within interface microchannels in a small group of awake and behaving animals and their firing patterns correlated directly with intramuscular recordings during locomotion. Of 38 potentials extracted, 19 were identified as motor axons reinnervating tibialis anterior or soleus muscles using spike triggered averaging. SIGNIFICANCE These results are evidence for motor axon regeneration through microchannels and are the first report of in vivo recordings from regenerated motor axons within microchannels in a small group of awake and behaving animals. These unique findings provide preliminary evidence that efferent, volitional motor potentials can be recorded from the microchannel-based peripheral neural interface; a critical requirement for any neural interface intended to facilitate direct neural control of external technologies.
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Affiliation(s)
- Russell K Gore
- Department of Neurology, Emory University School of Medicine, 550 Peachtree Street NE, 9th Floor MOT, Atlanta, GA 30308, USA. Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory School of Medicine, 1760 Haygood Drive NE, Atlanta, GA 30322, USA
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Abstract
This unit provides an overview of the principal electrophysiological techniques commonly used for the study of ionic currents and the ion channels that mediate them. These techniques include electroencephalograms (EEGs), electrocardiograms (ECGs), single- and multiunit extracellular recording, multielectrode arrays, transepithelial recording, impedance measurements, and current-clamp, voltage-clamp, patch-clamp, and lipid bilayer recording. The unit also discusses recent advances in high-throughput, automated electrophysiological techniques for drug discovery and the use of stem cells as a tissue source.
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Shinzawa G, Sato D, Kusunoki M, Karimata T, Sasaki H, Nakamura R, Feng Z, Nishina A, Nakamura T. Characteristics of spike rate of peripheral sympathetic nervous signal in streptozotocin-induced diabetic rats. Auton Neurosci 2013; 179:23-7. [PMID: 23830533 DOI: 10.1016/j.autneu.2013.06.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 05/27/2013] [Accepted: 06/14/2013] [Indexed: 11/25/2022]
Abstract
Although streptozotocin-administered (STZ) rats were widely used as an experimental diabetic neuropathy model, sympathetic nerve activity (SNA) in STZ rats has not been microneurographically evaluated so far. In the present study, we investigated the multi-unit, compound sympathetic signal from the sciatic nerve of rats 3 weeks after the administration of streptozotocin, and compared the signal with that of normal (control) rats. After obtaining the sympathetic signal, glucose was intravenously administered to make a transient increase in the blood glucose level to cause SNA change. The sympathetic burst rate did not show any statistical difference between groups at steady state. Even after the glucose administration, it changed little in each group. On the other hand, the firing rate of action potentials (AP-rate) in STZ group was significantly lower than that in control group before glucose administration (p<0.05). In addition, AP-rate was increased in control animals after glucose administration, but not in STZ rats. The results suggest a lower sympathetic tone and poorer response to glucose load under high blood glucose and low plasma insulin condition, and that the AP-rate may be useful for the evaluation of microneurographically measured, peripheral sympathetic activity.
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Affiliation(s)
- Go Shinzawa
- Department of Biomedical Information Engineering, Graduate School of Medical Science, Yamagata University, 2-2-2, Iida-nishi, Yamagata 990-9585, Japan
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Zotova EG, Arezzo JC. NON-INVASIVE EVALUATION OF NERVE CONDUCTION IN SMALL DIAMETER FIBERS IN THE RAT. PHYSIOLOGY JOURNAL 2013; 2013:254789. [PMID: 23580940 PMCID: PMC3620683 DOI: 10.1155/2013/254789] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A novel non-invasive technique was applied to measure velocity within slow conducting axons in the distal extreme of the sciatic nerve (i.e., digital nerve) in a rat model. The technique is based on the extraction of rectified multiple unit activity (MUA) from in vivo whole nerve compound responses. This method reliably identifies compound action potentials in thinly myelinated fibers conducting at a range of 9-18 m/s (Aδ axons), as well as in a subgroup of unmylinated C fibers conducting at approximately 1-2 m/s. The sensitivity of the method to C-fiber conduction was confirmed by the progressive decrement of the responses in the 1-2 m/s range over a 20-day period following the topical application of capsaicin (ANOVA p<0.03). Increasing the frequency of applied repetitive stimulation over a range of 0.75 Hz to 6.0 Hz produced slowing of conduction and a significant decrease in the magnitude of the compound C-fiber response (ANOVA p<0.01). This technique offers a unique opportunity for the non-invasive, repeatable, and quantitative assessment of velocity in the subsets of Aδ and C fibers in parallel with evaluation of fast nerve conduction.
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Affiliation(s)
- Elena G. Zotova
- Department of Neurology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - Joseph C. Arezzo
- Department of Neurology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
- Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
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Serra J. Microneurography: towards a biomarker of spontaneous pain. Pain 2012; 153:1989-1990. [PMID: 22820023 DOI: 10.1016/j.pain.2012.07.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 06/26/2012] [Accepted: 07/05/2012] [Indexed: 11/28/2022]
Affiliation(s)
- Jordi Serra
- MC Mutual, Barcelona, Spain Neuroscience Technologies, Barcelona, Spain Neuroscience Technologies, London, UK
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Luo J, Boosalis BJ, Thoreson WB, Margalit E. A comparison of optical and electrophysiological methods for recording retinal ganglion cells during electrical stimulation. Curr Eye Res 2012; 37:218-27. [PMID: 22335809 DOI: 10.3109/02713683.2011.652756] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE/AIM To compare the efficacy of optical techniques with electrophysiological recordings for mapping retinal activity in response to electrical stimulation. MATERIALS AND METHODS Whole cell patch clamp, Ca(2+) imaging (Fluo-4-AM), and Na(+) imaging (CoroNa Green-AM) techniques were used to detect responses of neurons from mouse and salamander retina to electrical stimulation. RESULTS Synaptic currents were observed in ≥23% of retinal ganglion cells (RGCs), indicating presynaptic Ca(2+) increases in the inner plexiform layer (IPL). Modest depolarization with 20-30 mM K(+) consistently evoked Ca(2+) responses measured with Fluo4, but Ca(2+) responses were almost never evoked by epiretinal stimulation. In salamander retina, responses were seen in the inner nuclear layer (INL) and IPL. In mouse retina, responses were also sometimes seen in the outer pexiform layer (OPL). OPL responses showed a longer latency than IPL responses, suggesting that outer retinal circuits do not trigger synaptic responses of RGCs. Simultaneous Ca(2+) imaging and electrophysiological recording of synaptic currents confirmed that Fluo4-loaded retinas remained responsive to stimulation. Epiretinal stimulation evoked action potentials in ≥67% of RGCs. CoroNa Green detected Na(+) changes stimulated by 20 mM K(+), but epiretinal stimulation did not evoke detectable Na(+) responses. Simultaneous imaging and electrophysiological recording confirmed the health of CoroNa Green-loaded retinas. We confirmed stimulation efficacy by simultaneously recording Na(+) changes and electrophysiological responses. CONCLUSIONS These data demonstrate that electrophysiological recordings show greater sensitivity than Na(+) or Ca(2+) imaging in response to electrical stimulation. The paucity of Ca(2+) responses is consistent with limited risk for Ca(2+)-mediated cell damage during electrical stimulation.
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Affiliation(s)
- Jianmin Luo
- Department of Ophthalmology and Visual Science, University of Nebraska Medical Center, Omaha, NE 68198, USA
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Microneurographic identification of spontaneous activity in C-nociceptors in neuropathic pain states in humans and rats. Pain 2011; 153:42-55. [PMID: 21993185 DOI: 10.1016/j.pain.2011.08.015] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 07/11/2011] [Accepted: 08/15/2011] [Indexed: 12/21/2022]
Abstract
C-nociceptors do not normally fire action potentials unless challenged by adequate noxious stimuli. However, in pathological states nociceptors may become hyperexcitable and may generate spontaneous ectopic discharges. The aim of this study was to compare rat neuropathic pain models and to assess their suitability to model the spontaneous C-nociceptor activity found in neuropathic pain patients. Studies were performed in normal rats (n=40), healthy human subjects (n=15), peripheral neuropathic pain patients (n=20), and in five rat neuropathic pain models: nerve crush (n=24), suture (n=14), chronic constriction injury (n=12), STZ-induced diabetic neuropathy (n=56), and ddC-induced neuropathy (n=15). Microneurographic recordings were combined with electrical stimulation to monitor activity in multiple C fibers. Stimulation at 0.25 Hz allowed spontaneous impulses to be identified by fluctuations in baseline latency. Abnormal latency fluctuations could be produced by several mechanisms, and spontaneous activity was most reliably identified by the presence of unexplained latency increases corresponding to two or more additional action potentials. Spontaneous activity was present in a proportion of mechano-insensitive C-nociceptors in the patients and all rat models. The three focal traumatic nerve injury models provided the highest proportion (59.5%), whereas the two polyneuropathy models had fewer (18.6%), and the patients had an intermediate proportion (33.3%). Spontaneously active mechano-sensitive C-nociceptors were not recorded. Microneurographic recordings of spontaneous activity in diseased C-nociceptors may be useful for both short- and long-term drug studies, both in animals and in humans.
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Tulleuda A, Cokic B, Callejo G, Saiani B, Serra J, Gasull X. TRESK channel contribution to nociceptive sensory neurons excitability: modulation by nerve injury. Mol Pain 2011; 7:30. [PMID: 21527011 PMCID: PMC3095542 DOI: 10.1186/1744-8069-7-30] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 04/28/2011] [Indexed: 01/01/2023] Open
Abstract
Background Neuronal hyperexcitability is a crucial phenomenon underlying spontaneous and evoked pain. In invertebrate nociceptors, the S-type leak K+ channel (analogous to TREK-1 in mammals) plays a critical role of in determining neuronal excitability following nerve injury. Few data are available on the role of leak K2P channels after peripheral axotomy in mammals. Results Here we describe that rat sciatic nerve axotomy induces hyperexcitability of L4-L5 DRG sensory neurons and decreases TRESK (K2P18.1) expression, a channel with a major contribution to total leak current in DRGs. While the expression of other channels from the same family did not significantly change, injury markers ATF3 and Cacna2d1 were highly upregulated. Similarly, acute sensory neuron dissociation (in vitro axotomy) produced marked hyperexcitability and similar total background currents compared with neurons injured in vivo. In addition, the sanshool derivative IBA, which blocked TRESK currents in transfected HEK293 cells and DRGs, increased intracellular calcium in 49% of DRG neurons in culture. Most IBA-responding neurons (71%) also responded to the TRPV1 agonist capsaicin, indicating that they were nociceptors. Additional evidence of a biological role of TRESK channels was provided by behavioral evidence of pain (flinching and licking), in vivo electrophysiological evidence of C-nociceptor activation following IBA injection in the rat hindpaw, and increased sensitivity to painful pressure after TRESK knockdown in vivo. Conclusions In summary, our results clearly support an important role of TRESK channels in determining neuronal excitability in specific DRG neurons subpopulations, and show that axonal injury down-regulates TRESK channels, therefore contributing to neuronal hyperexcitability.
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Affiliation(s)
- Astrid Tulleuda
- Neurophysiology Lab, Dept, Physiological Sciences I, Medical School, University of Barcelona-Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
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Truini A, Leone C, Di Stefano G, Biasiotta A, La Cesa S, Teofoli P, Padua L, Cruccu G. Topographical distribution of warmth, burning and itch sensations in healthy humans. Neurosci Lett 2011; 494:165-8. [DOI: 10.1016/j.neulet.2011.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Revised: 02/09/2011] [Accepted: 03/02/2011] [Indexed: 11/25/2022]
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Serra J, Solà R, Aleu J, Quiles C, Navarro X, Bostock H. Double and triple spikes in C-nociceptors in neuropathic pain states: An additional peripheral mechanism of hyperalgesia. Pain 2011; 152:343-353. [DOI: 10.1016/j.pain.2010.10.039] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Revised: 09/20/2010] [Accepted: 10/27/2010] [Indexed: 10/18/2022]
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Valls-Sole J, Castillo CD, Casanova-Molla J, Costa J. Clinical consequences of reinnervation disorders after focal peripheral nerve lesions. Clin Neurophysiol 2010; 122:219-28. [PMID: 20656551 DOI: 10.1016/j.clinph.2010.06.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 06/27/2010] [Accepted: 06/28/2010] [Indexed: 12/12/2022]
Abstract
Axonal regeneration and organ reinnervation are the necessary steps for functional recovery after a nerve lesion. However, these processes are frequently accompanied by collateral events that may not be beneficial, such as: (1) Uncontrolled branching of growing axons at the lesion site. (2) Misdirection of axons and target organ reinnervation errors, (3) Enhancement of excitability of the parent neuron, and (4) Compensatory activity in non-damaged nerves. Each one of those possible problems or a combination of them can be the underlying pathophysiological mechanism for some clinical conditions seen as a consequence of a nerve lesion. Reinnervation-related motor disorders are more likely to occur with lesions affecting nerves which innervate muscles with antagonistic functions, such as the facial, the laryngeal and the ulnar nerves. Motor disorders are better demonstrated than sensory disturbances, which might follow similar patterns. In some instances, the available examination methods give only scarce evidence for the positive diagnosis of reinnervation-related disorders in humans and the diagnosis of such condition can only be based on clinical observation. Whatever the lesion, though, the restitution of complex functions such as fine motor control and sensory discrimination would require not only a successful regeneration process but also a central nervous system reorganization in order to integrate the newly formed peripheral nerve structure into the prepared motor programs and sensory patterns.
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Affiliation(s)
- Josep Valls-Sole
- Department of Neurology, Hospital Clínic, Universitat de Barcelona, IDIBAPS (Institut d'Investigació Biomèdica August Pi i Sunyer), Spain.
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