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Ingram S, Chisholm KI, Wang F, De Koninck Y, Denk F, Goodwin GL. Assessing spontaneous sensory neuron activity using in vivo calcium imaging. Pain 2024; 165:1131-1141. [PMID: 38112748 PMCID: PMC11017743 DOI: 10.1097/j.pain.0000000000003116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 09/01/2023] [Accepted: 09/23/2023] [Indexed: 12/21/2023]
Abstract
ABSTRACT Heightened spontaneous activity in sensory neurons is often reported in individuals living with chronic pain. It is possible to study this activity in rodents using electrophysiology, but these experiments require great skill and can be prone to bias. Here, we have examined whether in vivo calcium imaging with GCaMP6s can be used as an alternative approach. We show that spontaneously active calcium transients can be visualised in the fourth lumbar dorsal root ganglion (L4 DRG) through in vivo imaging in a mouse model of inflammatory pain. Application of lidocaine to the nerve, between the inflamed site and the DRG, silenced spontaneous firing and revealed the true baseline level of calcium for spontaneously active neurons. We used these data to train a machine learning algorithm to predict when a neuron is spontaneously active. We show that our algorithm is accurate in 2 different models of pain: intraplantar complete Freund adjuvant and antigen-induced arthritis, with accuracies of 90.0% ±1.2 and 85.9% ±2.1, respectively, assessed against visual inspection by an experienced observer. The algorithm can also detect neuronal activity in imaging experiments generated in a different laboratory using a different microscope configuration (accuracy = 94.0% ±2.2). We conclude that in vivo calcium imaging can be used to assess spontaneous activity in sensory neurons and provide a Google Colaboratory Notebook to allow anyone easy access to our novel analysis tool, for the assessment of spontaneous neuronal activity in their own imaging setups.
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Affiliation(s)
- Sonia Ingram
- Sonia Ingram, Data Scientist, Contract Researcher for King's College London, London, United Kingdom
| | - Kim I. Chisholm
- Pain Centre Versus Arthritis, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Feng Wang
- CERVO Brain Research Centre, Québec Mental Health Institute, Quebec City, QC, Canada
- Faculty of Dentistry, Laval University, Quebec, Canada
| | - Yves De Koninck
- CERVO Brain Research Centre, Québec Mental Health Institute, Quebec City, QC, Canada
| | - Franziska Denk
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - George L. Goodwin
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
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2
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Jager SE, Goodwin G, Chisholm KI, Denk F. In vivo calcium imaging shows that satellite glial cells have increased activity in painful states. Brain Commun 2024; 6:fcae013. [PMID: 38638153 PMCID: PMC11024818 DOI: 10.1093/braincomms/fcae013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 11/22/2023] [Accepted: 01/17/2024] [Indexed: 04/20/2024] Open
Abstract
Satellite glial cells are important for proper neuronal function of primary sensory neurons for which they provide homeostatic support. Most research on satellite glial cell function has been performed with in vitro studies, but recent advances in calcium imaging and transgenic mouse models have enabled this first in vivo study of single-cell satellite glial cell function in mouse models of inflammation and neuropathic pain. We found that in naïve conditions, satellite glial cells do not respond in a time-locked fashion to neuronal firing. In painful inflammatory and neuropathic states, we detected time-locked signals in a subset of satellite glial cells, but only with suprathreshold stimulation of the sciatic nerve. Surprisingly, therefore, we conclude that most calcium signals in satellite glial cells seem to develop at arbitrary intervals not directly linked to neuronal activity patterns. More in line with expectations, our experiments also revealed that the number of active satellite glial cells was increased under conditions of inflammation or nerve injury. This could reflect the increased requirement for homeostatic support across dorsal root ganglion neuron populations, which are more active during such painful states.
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Affiliation(s)
- Sara E Jager
- Wolfson Centre for Age-related Diseases, King’s College London, Guy’s Campus, London SE1 1UL, UK
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - George Goodwin
- Wolfson Centre for Age-related Diseases, King’s College London, Guy’s Campus, London SE1 1UL, UK
| | - Kim I Chisholm
- Pain Centre Versus Arthritis, School of Life Sciences, University of Nottingham, Nottingham NG5 1PB, UK
| | - Franziska Denk
- Wolfson Centre for Age-related Diseases, King’s College London, Guy’s Campus, London SE1 1UL, UK
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3
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Chisholm KI, Finelli MJ. Enhancing research culture in academia: a spotlight on early career researchers. BMC Neurosci 2023; 24:46. [PMID: 37641034 PMCID: PMC10463509 DOI: 10.1186/s12868-023-00816-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 08/16/2023] [Indexed: 08/31/2023] Open
Abstract
This editorial highlights common challenges faced by early career researchers (ECRs) who play a crucial role in our research community. We propose that enhancing the experiences of ECRs will yield benefits to the entire scientific community and we give practical suggestions on how such improvements may be achieved.
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Affiliation(s)
- Kim I Chisholm
- Pain Centre Versus Arthritis, School of Life Sciences, University of Nottingham, Nottingham, UK.
| | - Mattéa J Finelli
- School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, UK.
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4
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Trendafilova T, Adhikari K, Schmid AB, Patel R, Polgár E, Chisholm KI, Middleton SJ, Boyle K, Dickie AC, Semizoglou E, Perez-Sanchez J, Bell AM, Ramirez-Aristeguieta LM, Khoury S, Ivanov A, Wildner H, Ferris E, Chacón-Duque JC, Sokolow S, Saad Boghdady MA, Herchuelz A, Faux P, Poletti G, Gallo C, Rothhammer F, Bedoya G, Zeilhofer HU, Diatchenko L, McMahon SB, Todd AJ, Dickenson AH, Ruiz-Linares A, Bennett DL. Sodium-calcium exchanger-3 regulates pain "wind-up": From human psychophysics to spinal mechanisms. Neuron 2022; 110:2571-2587.e13. [PMID: 35705078 PMCID: PMC7613464 DOI: 10.1016/j.neuron.2022.05.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 03/31/2022] [Accepted: 05/16/2022] [Indexed: 11/17/2022]
Abstract
Repeated application of noxious stimuli leads to a progressively increased pain perception; this temporal summation is enhanced in and predictive of clinical pain disorders. Its electrophysiological correlate is "wind-up," in which dorsal horn spinal neurons increase their response to repeated nociceptor stimulation. To understand the genetic basis of temporal summation, we undertook a GWAS of wind-up in healthy human volunteers and found significant association with SLC8A3 encoding sodium-calcium exchanger type 3 (NCX3). NCX3 was expressed in mouse dorsal horn neurons, and mice lacking NCX3 showed normal, acute pain but hypersensitivity to the second phase of the formalin test and chronic constriction injury. Dorsal horn neurons lacking NCX3 showed increased intracellular calcium following repetitive stimulation, slowed calcium clearance, and increased wind-up. Moreover, virally mediated enhanced spinal expression of NCX3 reduced central sensitization. Our study highlights Ca2+ efflux as a pathway underlying temporal summation and persistent pain, which may be amenable to therapeutic targeting.
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Affiliation(s)
| | - Kaustubh Adhikari
- School of Mathematics and Statistics, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, UK; Department of Genetics, Evolution and Environment, University College London, London, UK; Department of Cell and Developmental Biology, University College London, London, UK
| | - Annina B Schmid
- Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UK
| | - Ryan Patel
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Erika Polgár
- School of Psychology and Neuroscience, University of Glasgow, Glasgow, UK
| | - Kim I Chisholm
- Wolfson Centre for Age-Related Diseases, King's College London, London, UK
| | - Steven J Middleton
- Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UK
| | - Kieran Boyle
- School of Psychology and Neuroscience, University of Glasgow, Glasgow, UK
| | - Allen C Dickie
- School of Psychology and Neuroscience, University of Glasgow, Glasgow, UK
| | | | | | - Andrew M Bell
- School of Psychology and Neuroscience, University of Glasgow, Glasgow, UK
| | | | - Samar Khoury
- McGill University and Genome Quebec Innovation Centre, Montreal, QC, Canada
| | - Aleksandar Ivanov
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Hendrik Wildner
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Eleanor Ferris
- Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UK
| | - Juan-Camilo Chacón-Duque
- Department of Genetics, Evolution and Environment, University College London, London, UK; Centre for Palaeogenetics, Stockholm, Sweden; Department of Archaeology and Classical Studies, Stockholm University, Stockholm, Sweden
| | - Sophie Sokolow
- Laboratoire de Pharmacodynamie et de Thérapeutique Faculté de Médecine Université Libre de Bruxelles, Brussels, Belgium; School of Nursing, University of California, Los Angeles, Los Angeles, CA, USA
| | | | - André Herchuelz
- Laboratoire de Pharmacodynamie et de Thérapeutique Faculté de Médecine Université Libre de Bruxelles, Brussels, Belgium
| | - Pierre Faux
- CNRS, EFS, ADES, Aix-Marseille Université, Marseille, France
| | - Giovanni Poletti
- Unidad de Neurobiologia Molecular y Genética, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Carla Gallo
- Unidad de Neurobiologia Molecular y Genética, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | | | - Gabriel Bedoya
- GENMOL (Genética Molecular), Universidad de Antioquia, Medellin, Colombia
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland; Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Luda Diatchenko
- McGill University and Genome Quebec Innovation Centre, Montreal, QC, Canada
| | - Stephen B McMahon
- Wolfson Centre for Age-Related Diseases, King's College London, London, UK
| | - Andrew J Todd
- School of Psychology and Neuroscience, University of Glasgow, Glasgow, UK
| | - Anthony H Dickenson
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Andres Ruiz-Linares
- Department of Genetics, Evolution and Environment, University College London, London, UK; CNRS, EFS, ADES, Aix-Marseille Université, Marseille, France; Ministry of Education Key Laboratory of Contemporary Anthropology and Collaborative Innovation Center of Genetics and Development, School of Life Sciences and Human Phenome Institute, Fudan University, Shanghai, China.
| | - David L Bennett
- Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UK.
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Chisholm KI, Lo Re L, Polgár E, Gutierrez-Mecinas M, Todd AJ, McMahon SB. Encoding of cutaneous stimuli by lamina I projection neurons. Pain 2021; 162:2405-2417. [PMID: 33769365 PMCID: PMC8374708 DOI: 10.1097/j.pain.0000000000002226] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 12/11/2020] [Accepted: 01/04/2021] [Indexed: 11/26/2022]
Abstract
ABSTRACT Lamina I of the dorsal horn, together with its main output pathway, lamina I projection neurons, has long been implicated in the processing of nociceptive stimuli, as well as the development of chronic pain conditions. However, the study of lamina I projection neurons is hampered by technical challenges, including the low throughput and selection biases of traditional electrophysiological techniques. Here we report on a technique that uses anatomical labelling strategies and in vivo imaging to simultaneously study a network of lamina I projection neurons in response to electrical and natural stimuli. Although we were able to confirm the nociceptive involvement of this group of cells, we also describe an unexpected preference for innocuous cooling stimuli. We were able to characterize the thermal responsiveness of these cells in detail and found cooling responses decline when exposed to stable cold temperatures maintained for more than a few seconds, as well as to encode the intensity of the end temperature, while heating responses showed an unexpected reliance on adaptation temperatures.
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Affiliation(s)
- Kim I. Chisholm
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Laure Lo Re
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Erika Polgár
- Spinal Cord Group, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Maria Gutierrez-Mecinas
- Spinal Cord Group, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Andrew J. Todd
- Spinal Cord Group, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Stephen B. McMahon
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
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6
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Lloyd JO, Chisholm KI, Oehle B, Jones MG, Okine BN, Al-Kaisy A, Lambru G, McMahon SB, Andreou AP. Cortical Mechanisms of Single-Pulse Transcranial Magnetic Stimulation in Migraine. Neurotherapeutics 2020; 17:1973-1987. [PMID: 32632772 PMCID: PMC7851313 DOI: 10.1007/s13311-020-00879-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Single-pulse transcranial magnetic stimulation (sTMS) of the occipital cortex is an effective migraine treatment. However, its mechanism of action and cortical effects of sTMS in migraine are yet to be elucidated. Using calcium imaging and GCaMP-expressing mice, sTMS did not depolarise neurons and had no effect on vascular tone. Pre-treatment with sTMS, however, significantly affected some characteristics of the cortical spreading depression (CSD) wave, the correlate of migraine aura. sTMS inhibited spontaneous neuronal firing in the visual cortex in a dose-dependent manner and attenuated L-glutamate-evoked firing, but not in the presence of GABAA/B antagonists. In the CSD model, sTMS increased the CSD electrical threshold, but not in the presence of GABAA/B antagonists. We first report here that sTMS at intensities similar to those used in the treatment of migraine, unlike traditional sTMS applied in other neurological fields, does not excite cortical neurons but it reduces spontaneous cortical neuronal activity and suppresses the migraine aura biological substrate, potentially by interacting with GABAergic circuits.
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Affiliation(s)
- Joseph O Lloyd
- Headache Research-Wolfson CARD, Guy's Campus, King's College London, London, UK
| | - Kim I Chisholm
- Department of Neurorestoration, Wolfson Centre for Age-Related Diseases, King's College London, London, UK
| | - Beatrice Oehle
- Department of Neurorestoration, Wolfson Centre for Age-Related Diseases, King's College London, London, UK
| | - Martyn G Jones
- Department of Neurorestoration, Wolfson Centre for Age-Related Diseases, King's College London, London, UK
- Zenith Neurotech Ltd, London, UK
| | - Bright N Okine
- Headache Research-Wolfson CARD, Guy's Campus, King's College London, London, UK
| | - Adnan Al-Kaisy
- Pain Management and Neuromodulation Centre, Guy's and St Thomas's NHS Foundation Trust, King's Health Partners, London, UK
| | - Giorgio Lambru
- Headache Research-Wolfson CARD, Guy's Campus, King's College London, London, UK
- Headache Centre, Guy's and St Thomas's NHS Foundation Trust, King's Health Partners, London, UK
| | - Stephen B McMahon
- Department of Neurorestoration, Wolfson Centre for Age-Related Diseases, King's College London, London, UK
| | - Anna P Andreou
- Headache Research-Wolfson CARD, Guy's Campus, King's College London, London, UK.
- Headache Centre, Guy's and St Thomas's NHS Foundation Trust, King's Health Partners, London, UK.
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7
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Kucharczyk MW, Chisholm KI, Denk F, Dickenson AH, Bannister K, McMahon SB. The impact of bone cancer on the peripheral encoding of mechanical pressure stimuli. Pain 2020; 161:1894-1905. [PMID: 32701848 PMCID: PMC7365668 DOI: 10.1097/j.pain.0000000000001880] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 02/25/2020] [Accepted: 03/23/2020] [Indexed: 11/25/2022]
Abstract
Skeletal metastases are frequently accompanied by chronic pain that is mechanoceptive in nature. Mechanistically, cancer-induced bone pain (CIBP) is mediated by peripheral sensory neurons innervating the cancerous site, the cell bodies of which are housed in the dorsal root ganglia (DRG). How these somatosensory neurons encode sensory information in CIBP remains only partly explained. Using a validated rat model, we first confirmed cortical bone destruction in CIBP but not sham-operated rats (day 14 after surgery, designated "late"-stage bone cancer). This occurred with behavioural mechanical hypersensitivity (Kruskal-Wallis H for independent samples; CIBP vs sham-operated, day 14; P < 0.0001). Next, hypothesising that the proportion and phenotype of primary afferents would be altered in the disease state, dorsal root ganglia in vivo imaging of genetically encoded calcium indicators and Markov Cluster Analysis were used to analyse 1748 late-stage CIBP (n = 10) and 757 sham-operated (n = 9), neurons. Distinct clusters of responses to peripheral stimuli were revealed. In CIBP rats, upon knee compression of the leg ipsilateral to the tumour, (1) 3 times as many sensory afferents responded (repeated-measures analysis of variance: P < 0.0001 [vs sham]); (2) there were significantly more small neurons responding (Kruskal-Wallis for independent samples (vs sham): P < 0.0001); and (3) approximately 13% of traced tibial cavity afferents responded (no difference observed between CIBP and sham-operated animals). We conclude that an increased sensory afferent response is present in CIBP rats, and this is likely to reflect afferent recruitment from outside of the bone rather than increased intraosseous afferent activity.
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Affiliation(s)
- Mateusz W. Kucharczyk
- Central Modulation of Pain Group, Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, United Kingdom
| | - Kim I. Chisholm
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Franziska Denk
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Anthony H. Dickenson
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, United Kingdom
| | - Kirsty Bannister
- Central Modulation of Pain Group, Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Stephen B. McMahon
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
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8
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Chisholm KI, Khovanov N, Lopes DM, La Russa F, McMahon SB. Large Scale In Vivo Recording of Sensory Neuron Activity with GCaMP6. eNeuro 2018; 5:ENEURO.0417-17.2018. [PMID: 29662940 PMCID: PMC5898788 DOI: 10.1523/eneuro.0417-17.2018] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 01/22/2018] [Accepted: 01/30/2018] [Indexed: 12/19/2022] Open
Abstract
Greater emphasis on the study of intact cellular networks in their physiological environment has led to rapid advances in intravital imaging of the central nervous system (CNS), while the peripheral system remains largely unexplored. To assess large networks of sensory neurons, we selectively label primary afferents with GCaMP6s in male and female C57bl/6 mice and visualize their functional responses to peripheral stimulation in vivo. We show that we are able to monitor the activity of hundreds of sensory neurons simultaneously, with sufficient sensitivity to detect, in most cases, single action potentials with a typical rise time of around 200 ms, and an exponential decay with a time constant of approximately 700 ms. With this technique we are able to characterize the responses of large populations of sensory neurons to innocuous and noxious mechanical and thermal stimuli under normal and inflammatory conditions. We demonstrate that the majority of primary afferents are polymodal with between 50-80% of thermally sensitive DRG neurons responding also to noxious mechanical stimulation. We also specifically assess the small population of peripheral cold neurons and demonstrate significant sensitization to cooling after a model of sterile and persistent inflammation, with significantly increased sensitivity already at decreases of 5°C when compared to uninflamed responses. This not only reveals interesting new insights into the (patho)physiology of the peripheral nervous system but also demonstrates the sensitivity of this imaging technique to physiological changes in primary afferents.
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Affiliation(s)
- Kim I Chisholm
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, London SE1 1UL, United Kingdom
| | - Nikita Khovanov
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, London SE1 1UL, United Kingdom
| | - Douglas M Lopes
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, London SE1 1UL, United Kingdom
| | - Federica La Russa
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, London SE1 1UL, United Kingdom
| | - Stephen B McMahon
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, London SE1 1UL, United Kingdom
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Lopes DM, Denk F, Chisholm KI, Suddason T, Durrieux C, Thakur M, Gentry C, McMahon SB. Peripheral inflammatory pain sensitisation is independent of mast cell activation in male mice. Pain 2017; 158:1314-1322. [PMID: 28394852 PMCID: PMC5472008 DOI: 10.1097/j.pain.0000000000000917] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 03/23/2017] [Accepted: 03/27/2017] [Indexed: 01/06/2023]
Abstract
The immune and sensory systems are known for their close proximity and interaction. Indeed, in a variety of pain states, a myriad of different immune cells are activated and recruited, playing a key role in neuronal sensitisation. During inflammatory pain it is thought that mast cells (MC) are one of the immune cell types involved in this process, but so far the evidence outlining their direct effect on neuronal cells remains unclear. To clarify whether MC are involved in inflammatory pain states, we used a transgenic mouse line (Mctp5Cre-iDTR) in which MC could be depleted in an inducible manner by administration of diphtheria toxin. Our results show that ablation of MC in male mice did not result in any change in mechanical and thermal hypersensitivity in the CFA model of inflammatory pain. Similarly, edema and temperature triggered by CFA inflammation at the injection site remained identical in MC depleted mice compared with their littermate controls. In addition, we show that Mctp5Cre-iDTR mice display normal levels of mechanical hypersensitivity after local injection of nerve growth factor (NGF), a factor well characterised to produce peripheral sensitisation and for being upregulated upon injury and inflammation. We also demonstrate that NGF treatment in vitro does not lead to an increased level of tumor necrosis factor-α in bone marrow-derived MC. Furthermore, our qRT-PCR data reveal that MC express negligible levels of NGF receptors, thereby explaining the lack of response to NGF. Together, our data suggest that MC do not play a direct role in peripheral sensitisation during inflammatory conditions.
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Affiliation(s)
- Douglas M. Lopes
- Wolfson Centre for Age-Related Diseases, King's College London, United Kingdom
| | - Franziska Denk
- Wolfson Centre for Age-Related Diseases, King's College London, United Kingdom
| | - Kim I. Chisholm
- Wolfson Centre for Age-Related Diseases, King's College London, United Kingdom
| | - Tesha Suddason
- Wolfson Centre for Age-Related Diseases, King's College London, United Kingdom
| | - Camille Durrieux
- Wolfson Centre for Age-Related Diseases, King's College London, United Kingdom
| | - Matthew Thakur
- Wolfson Centre for Age-Related Diseases, King's College London, United Kingdom
| | - Clive Gentry
- Wolfson Centre for Age-Related Diseases, King's College London, United Kingdom
| | - Stephen B. McMahon
- Wolfson Centre for Age-Related Diseases, King's College London, United Kingdom
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10
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Chisholm KI, Ida KK, Davies AL, Tachtsidis I, Papkovsky DB, Dyson A, Singer M, Duchen MR, Smith KJ. Hypothermia protects brain mitochondrial function from hypoxemia in a murine model of sepsis. J Cereb Blood Flow Metab 2016; 36:1955-1964. [PMID: 26661160 PMCID: PMC5094296 DOI: 10.1177/0271678x15606457] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 07/14/2015] [Indexed: 11/17/2022]
Abstract
Sepsis is commonly associated with brain dysfunction, but the underlying mechanisms remain unclear, although mitochondrial dysfunction and microvascular abnormalities have been implicated. We therefore assessed whether cerebral mitochondrial dysfunction during systemic endotoxemia in mice increased mitochondrial sensitivity to a further bioenergetic insult (hyoxemia), and whether hypothermia could improve outcome. Mice (C57bl/6) were injected intraperitoneally with lipopolysaccharide (LPS) (5 mg/kg; n = 85) or saline (0.01 ml/g; n = 47). Six, 24 and 48 h later, we used confocal imaging in vivo to assess cerebral mitochondrial redox potential and cortical oxygenation in response to changes in inspired oxygen. The fraction of inspired oxygen (FiO2) at which the cortical redox potential changed was compared between groups. In a subset of animals, spontaneous hypothermia was maintained or controlled hypothermia induced during imaging. Decreasing FiO2 resulted in a more reduced cerebral redox state around veins, but preserved oxidation around arteries. This pattern appeared at a higher FiO2 in LPS-injected animals, suggesting an increased sensitivity of cortical mitochondria to hypoxemia. This increased sensitivity was accompanied by a decrease in cortical oxygenation, but was attenuated by hypothermia. These results suggest that systemic endotoxemia influences cortical oxygenation and mitochondrial function, and that therapeutic hypothermia can be protective.
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Affiliation(s)
| | - Keila K Ida
- Institute of Neurology, University College London, UK.,Anaesthesiology LIM-8, Medical School, University of São Paulo, Brazil
| | | | - Ilias Tachtsidis
- Medical Physics and Biomedical Engineering, University College London, UK
| | - Dmitri B Papkovsky
- School of Biochemistry and Cell Biology, University College Cork, Ireland
| | - Alex Dyson
- Bloomsbury Institute of Intensive Care Medicine, University College London, UK
| | - Mervyn Singer
- Bloomsbury Institute of Intensive Care Medicine, University College London, UK
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Ida KK, Malbouisson LMS, Otsuki DA, Chisholm KI, Dyson A, Singer M, Duchen MR, Smith KJ. 0036. Confocal imaging of impaired mitochondrial function in the cerebral cortex of rats during haemorrhagic shock in vivo. Intensive Care Med Exp 2014. [PMCID: PMC4797095 DOI: 10.1186/2197-425x-2-s1-o9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Chisholm KI, Davies AL, Singer M, Dyson A, Ida KK, Tachtsidis I, Duchen MR, Smith KJ. 0033. Hypothermia protects brain mitochondrial function from hypoxia in sepsis. Intensive Care Med Exp 2014. [PMCID: PMC4797910 DOI: 10.1186/2197-425x-2-s1-o6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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