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Li X, Prudente AS, Prato V, Guo X, Hao H, Jones F, Figoli S, Mullen P, Wang Y, Tonnello R, Lee SH, Shah S, Maffei B, Berta T, Du X, Gamper N. Peripheral gating of pain by glial endozepine. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.20.567848. [PMID: 38045227 PMCID: PMC10690183 DOI: 10.1101/2023.11.20.567848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
We report that diazepam binding inhibitor (DBI) is a glial messenger mediating satellite glia-sensory neuron crosstalk in the dorsal root ganglion (DRG). DBI is highly and specifically expressed in satellite glia cells (SGCs) of mice, rat and human, but not in sensory neurons or other DRG-resident cells. Knockdown of DBI results in a robust mechanical hypersensitivity without significant effects on other sensory modalities. In vivo overexpression of DBI in SGCs reduces sensitivity to mechanical stimulation and alleviates mechanical allodynia in neuropathic and inflammatory pain models. We further show that DBI acts as a partial agonist and positive allosteric modulator at the neuronal GABAA receptors, particularly strongly effecting those with a high-affinity benzodiazepine binding site. Such receptors are selectively expressed by a subpopulation of mechanosensitive DRG neurons and these are also more enwrapped with DBI-expressing glia, as compared to other DRG neurons, suggesting a mechanism for specific effect of DBI on mechanosensation. These findings identified a new, peripheral neuron-glia communication mechanism modulating pain signalling, which can be targeted therapeutically.
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Affiliation(s)
- Xinmeng Li
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Arthur Silveira Prudente
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Vincenzo Prato
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Xianchuan Guo
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Han Hao
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Frederick Jones
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK
- Department of Life Sciences, Manchester Metropolitan University, Manchester, UK
| | - Sofia Figoli
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Pierce Mullen
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Yujin Wang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Raquel Tonnello
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Sang Hoon Lee
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Shihab Shah
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Benito Maffei
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Temugin Berta
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Xiaona Du
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Nikita Gamper
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK
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Yang J, Prescott SA. Homeostatic regulation of neuronal function: importance of degeneracy and pleiotropy. Front Cell Neurosci 2023; 17:1184563. [PMID: 37333893 PMCID: PMC10272428 DOI: 10.3389/fncel.2023.1184563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 05/16/2023] [Indexed: 06/20/2023] Open
Abstract
Neurons maintain their average firing rate and other properties within narrow bounds despite changing conditions. This homeostatic regulation is achieved using negative feedback to adjust ion channel expression levels. To understand how homeostatic regulation of excitability normally works and how it goes awry, one must consider the various ion channels involved as well as the other regulated properties impacted by adjusting those channels when regulating excitability. This raises issues of degeneracy and pleiotropy. Degeneracy refers to disparate solutions conveying equivalent function (e.g., different channel combinations yielding equivalent excitability). This many-to-one mapping contrasts the one-to-many mapping described by pleiotropy (e.g., one channel affecting multiple properties). Degeneracy facilitates homeostatic regulation by enabling a disturbance to be offset by compensatory changes in any one of several different channels or combinations thereof. Pleiotropy complicates homeostatic regulation because compensatory changes intended to regulate one property may inadvertently disrupt other properties. Co-regulating multiple properties by adjusting pleiotropic channels requires greater degeneracy than regulating one property in isolation and, by extension, can fail for additional reasons such as solutions for each property being incompatible with one another. Problems also arise if a perturbation is too strong and/or negative feedback is too weak, or because the set point is disturbed. Delineating feedback loops and their interactions provides valuable insight into how homeostatic regulation might fail. Insofar as different failure modes require distinct interventions to restore homeostasis, deeper understanding of homeostatic regulation and its pathological disruption may reveal more effective treatments for chronic neurological disorders like neuropathic pain and epilepsy.
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Affiliation(s)
- Jane Yang
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON, Canada
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Steven A. Prescott
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON, Canada
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
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Hao H, Ramli R, Wang C, Liu C, Shah S, Mullen P, Lall V, Jones F, Shao J, Zhang H, Jaffe DB, Gamper N, Du X. Dorsal root ganglia control nociceptive input to the central nervous system. PLoS Biol 2023; 21:e3001958. [PMID: 36603052 PMCID: PMC9847955 DOI: 10.1371/journal.pbio.3001958] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 01/18/2023] [Accepted: 12/13/2022] [Indexed: 01/06/2023] Open
Abstract
Accumulating observations suggest that peripheral somatosensory ganglia may regulate nociceptive transmission, yet direct evidence is sparse. Here, in experiments on rats and mice, we show that the peripheral afferent nociceptive information undergoes dynamic filtering within the dorsal root ganglion (DRG) and suggest that this filtering occurs at the axonal bifurcations (t-junctions). Using synchronous in vivo electrophysiological recordings from the peripheral and central processes of sensory neurons (in the spinal nerve and dorsal root), ganglionic transplantation of GABAergic progenitor cells, and optogenetics, we demonstrate existence of tonic and dynamic filtering of action potentials traveling through the DRG. Filtering induced by focal application of GABA or optogenetic GABA release from the DRG-transplanted GABAergic progenitor cells was specific to nociceptive fibers. Light-sheet imaging and computer modeling demonstrated that, compared to other somatosensory fiber types, nociceptors have shorter stem axons, making somatic control over t-junctional filtering more efficient. Optogenetically induced GABA release within DRG from the transplanted GABAergic cells enhanced filtering and alleviated hypersensitivity to noxious stimulation produced by chronic inflammation and neuropathic injury in vivo. These findings support "gating" of pain information by DRGs and suggest new therapeutic approaches for pain relief.
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Affiliation(s)
- Han Hao
- Department of Pharmacology, Hebei Medical University; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Shijiazhuang, China
| | - Rosmaliza Ramli
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
- School of Dental Sciences, Universiti Sains Malaysia, Kelantan, Malaysia
| | - Caixue Wang
- Department of Pharmacology, Hebei Medical University; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Shijiazhuang, China
| | - Chao Liu
- Department of Animal Care, Hebei Medical University; The Key Laboratory of Experimental Animal, Hebei Province; Shijiazhuang, China
| | - Shihab Shah
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Pierce Mullen
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Varinder Lall
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Frederick Jones
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Jicheng Shao
- Department of Pharmacology, Hebei Medical University; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Shijiazhuang, China
| | - Hailin Zhang
- Department of Pharmacology, Hebei Medical University; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Shijiazhuang, China
| | - David B. Jaffe
- Department of Neuroscience, Developmental and Regenerative Biology, The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Nikita Gamper
- Department of Pharmacology, Hebei Medical University; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Shijiazhuang, China
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Xiaona Du
- Department of Pharmacology, Hebei Medical University; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Shijiazhuang, China
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Yang J, Shakil H, Ratté S, Prescott SA. Minimal requirements for a neuron to co-regulate many properties and the implications for ion channel correlations and robustness. eLife 2022; 11:72875. [PMID: 35293858 PMCID: PMC8986315 DOI: 10.7554/elife.72875] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 03/03/2022] [Indexed: 11/13/2022] Open
Abstract
Neurons regulate their excitability by adjusting their ion channel levels. Degeneracy – achieving equivalent outcomes (excitability) using different solutions (channel combinations) – facilitates this regulation by enabling a disruptive change in one channel to be offset by compensatory changes in other channels. But neurons must coregulate many properties. Pleiotropy – the impact of one channel on more than one property – complicates regulation because a compensatory ion channel change that restores one property to its target value often disrupts other properties. How then does a neuron simultaneously regulate multiple properties? Here, we demonstrate that of the many channel combinations producing the target value for one property (the single-output solution set), few combinations produce the target value for other properties. Combinations producing the target value for two or more properties (the multioutput solution set) correspond to the intersection between single-output solution sets. Properties can be effectively coregulated only if the number of adjustable channels (nin) exceeds the number of regulated properties (nout). Ion channel correlations emerge during homeostatic regulation when the dimensionality of solution space (nin − nout) is low. Even if each property can be regulated to its target value when considered in isolation, regulation as a whole fails if single-output solution sets do not intersect. Our results also highlight that ion channels must be coadjusted with different ratios to regulate different properties, which suggests that each error signal drives modulatory changes independently, despite those changes ultimately affecting the same ion channels.
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Affiliation(s)
- Jane Yang
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Canada
| | - Husain Shakil
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Canada
| | - Stéphanie Ratté
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Canada
| | - Steven Alec Prescott
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Canada
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Middleton SJ, Perez-Sanchez J, Dawes JM. The structure of sensory afferent compartments in health and disease. J Anat 2021; 241:1186-1210. [PMID: 34528255 PMCID: PMC9558153 DOI: 10.1111/joa.13544] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 08/12/2021] [Accepted: 08/30/2021] [Indexed: 12/20/2022] Open
Abstract
Primary sensory neurons are a heterogeneous population of cells able to respond to both innocuous and noxious stimuli. Like most neurons they are highly compartmentalised, allowing them to detect, convey and transfer sensory information. These compartments include specialised sensory endings in the skin, the nodes of Ranvier in myelinated axons, the cell soma and their central terminals in the spinal cord. In this review, we will highlight the importance of these compartments to primary afferent function, describe how these structures are compromised following nerve damage and how this relates to neuropathic pain.
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Affiliation(s)
- Steven J Middleton
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | | | - John M Dawes
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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Interactions among diameter, myelination, and the Na/K pump affect axonal resilience to high-frequency spiking. Proc Natl Acad Sci U S A 2021; 118:2105795118. [PMID: 34353911 PMCID: PMC8364126 DOI: 10.1073/pnas.2105795118] [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] [Indexed: 01/09/2023] Open
Abstract
The reliability of spike propagation in axons is determined by complex interactions among ionic currents, ion pumps, and morphological properties. We use compartment-based modeling to reveal that interactions of diameter, myelination, and the Na/K pump determine the reliability of high-frequency spike propagation. By acting as a “reservoir” of nodal Na+ influx, myelinated compartments efficiently increase propagation reliability. Although spike broadening was thought to oppose fast spiking, its effect on spike propagation is complicated, depending on the balance of Na+ channel inactivation gate recovery, Na+ influx, and axial charge. Our findings suggest that slow Na+ removal influences axonal resilience to high-frequency spike propagation and that different strategies may be required to overcome this constraint in different neurons. Axons reliably conduct action potentials between neurons and/or other targets. Axons have widely variable diameters and can be myelinated or unmyelinated. Although the effect of these factors on propagation speed is well studied, how they constrain axonal resilience to high-frequency spiking is incompletely understood. Maximal firing frequencies range from ∼1 Hz to >300 Hz across neurons, but the process by which Na/K pumps counteract Na+ influx is slow, and the extent to which slow Na+ removal is compatible with high-frequency spiking is unclear. Modeling the process of Na+ removal shows that large-diameter axons are more resilient to high-frequency spikes than are small-diameter axons, because of their slow Na+ accumulation. In myelinated axons, the myelinated compartments between nodes of Ranvier act as a “reservoir” to slow Na+ accumulation and increase the reliability of axonal propagation. We now find that slowing the activation of K+ current can increase the Na+ influx rate, and the effect of minimizing the overlap between Na+ and K+ currents on spike propagation resilience depends on complex interactions among diameter, myelination, and the Na/K pump density. Our results suggest that, in neurons with different channel gating kinetic parameters, different strategies may be required to improve the reliability of axonal propagation.
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