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Zhang D, Turecek J, Choi S, Delisle M, Pamplona CL, Meltzer S, Ginty DD. C-LTMRs mediate wet dog shakes via the spinoparabrachial pathway. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.10.597395. [PMID: 38915692 PMCID: PMC11195135 DOI: 10.1101/2024.06.10.597395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Mammals perform rapid oscillations of their body- "wet dog shakes" -to remove water and irritants from their back hairy skin. The somatosensory mechanisms underlying this stereotypical behavior are unknown. We report that Piezo2-dependent mechanosensation mediates wet dog shakes evoked by water or oil droplets applied to hairy skin of mice. Unmyelinated low-threshold mechanoreceptors (C-LTMRs) were strongly activated by oil droplets and their optogenetic activation elicited wet dog shakes. Ablation of C-LTMRs attenuated this behavior. Moreover, C-LTMRs synaptically couple to spinoparabrachial (SPB) neurons, and optogenetically inhibiting SPB neuron synapses and excitatory neurons in the parabrachial nucleus impaired both oil droplet- and C-LTMR-evoked wet dog shakes. Thus, a C-LTMR- spinoparabrachial pathway mediates wet dog shakes for rapid and effective removal of foreign particles from back hairy skin.
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2
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Bell AM, Utting C, Dickie AC, Kucharczyk MW, Quillet R, Gutierrez-Mecinas M, Razlan ANB, Cooper AH, Lan Y, Hachisuka J, Weir GA, Bannister K, Watanabe M, Kania A, Hoon MA, Macaulay IC, Denk F, Todd AJ. Deep sequencing of Phox2a nuclei reveals five classes of anterolateral system neurons. Proc Natl Acad Sci U S A 2024; 121:e2314213121. [PMID: 38805282 PMCID: PMC11161781 DOI: 10.1073/pnas.2314213121] [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: 08/29/2023] [Accepted: 04/16/2024] [Indexed: 05/30/2024] Open
Abstract
The anterolateral system (ALS) is a major ascending pathway from the spinal cord that projects to multiple brain areas and underlies the perception of pain, itch, and skin temperature. Despite its importance, our understanding of this system has been hampered by the considerable functional and molecular diversity of its constituent cells. Here, we use fluorescence-activated cell sorting to isolate ALS neurons belonging to the Phox2a-lineage for single-nucleus RNA sequencing. We reveal five distinct clusters of ALS neurons (ALS1-5) and document their laminar distribution in the spinal cord using in situ hybridization. We identify three clusters of neurons located predominantly in laminae I-III of the dorsal horn (ALS1-3) and two clusters with cell bodies located in deeper laminae (ALS4 and ALS5). Our findings reveal the transcriptional logic that underlies ALS neuronal diversity in the adult mouse and uncover the molecular identity of two previously identified classes of projection neurons. We also show that these molecular signatures can be used to target groups of ALS neurons using retrograde viral tracing. Overall, our findings provide a valuable resource for studying somatosensory biology and targeting subclasses of ALS neurons.
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Affiliation(s)
- Andrew M. Bell
- Spinal Cord Group, School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, GlasgowG12 8QQ, United Kingdom
- Small Animal Clinical Sciences, School of Biodiversity, One Health and Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, GlasgowG12 8QQ, United Kingdom
| | | | - Allen C. Dickie
- Spinal Cord Group, School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, GlasgowG12 8QQ, United Kingdom
| | - Mateusz W. Kucharczyk
- The Wolfson Centre for Age-Related Diseases, King’s College London, LondonWC2R 2LS, United Kingdom
- Cancer Neurophysiology Group, Lukasiewicz-PORT, Polish Center for Technology Development, Wroclaw54-066, Poland
| | - Raphaëlle Quillet
- Spinal Cord Group, School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, GlasgowG12 8QQ, United Kingdom
| | - Maria Gutierrez-Mecinas
- Spinal Cord Group, School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, GlasgowG12 8QQ, United Kingdom
| | - Aimi N. B. Razlan
- Spinal Cord Group, School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, GlasgowG12 8QQ, United Kingdom
| | - Andrew H. Cooper
- Spinal Cord Group, School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, GlasgowG12 8QQ, United Kingdom
| | - Yuxuan Lan
- Earlham Institute, NorwichNRU 7UZ, United Kingdom
| | - Junichi Hachisuka
- Spinal Cord Group, School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, GlasgowG12 8QQ, United Kingdom
| | - Greg A. Weir
- Spinal Cord Group, School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, GlasgowG12 8QQ, United Kingdom
| | - Kirsty Bannister
- The Wolfson Centre for Age-Related Diseases, King’s College London, LondonWC2R 2LS, United Kingdom
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo060-8638, Japan
| | - Artur Kania
- Neural Circuit Development Research Unit, Institut de Recherches Cliniques de Montréal, Montréal, QCH2W 1R7, Canada
| | - Mark A. Hoon
- Molecular Genetics Section, National Institute of Dental and Craniofacial Research/NIH, Bethesda, MD 20892
| | | | - Franziska Denk
- The Wolfson Centre for Age-Related Diseases, King’s College London, LondonWC2R 2LS, United Kingdom
| | - Andrew J. Todd
- Spinal Cord Group, School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, GlasgowG12 8QQ, United Kingdom
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3
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Yarmolinsky DA, Zeng X, MacKinnon-Booth N, Greene C, Kim C, Woolf CJ. Selective modification of ascending spinal outputs in acute and neuropathic pain states. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.08.588581. [PMID: 38645252 PMCID: PMC11030409 DOI: 10.1101/2024.04.08.588581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
Pain hypersensitivity arises from the plasticity of peripheral and spinal somatosensory neurons, which modifies nociceptive input to the brain and alters pain perception. We utilized chronic calcium imaging of spinal dorsal horn neurons to determine how the representation of somatosensory stimuli in the anterolateral tract, the principal pathway transmitting nociceptive signals to the brain, changes between distinct pain states. In healthy conditions, we identify stable, narrowly tuned outputs selective for cooling or warming, and a neuronal ensemble activated by intense/noxious thermal and mechanical stimuli. Induction of an acute peripheral sensitization with capsaicin selectively and transiently retunes nociceptive output neurons to encode low-intensity stimuli. In contrast, peripheral nerve injury-induced neuropathic pain results in a persistent suppression of innocuous spinal outputs coupled with activation of a normally silent population of high-threshold neurons. These results demonstrate the differential modulation of specific spinal outputs to the brain during nociceptive and neuropathic pain states.
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4
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Serafin EK, Yoo JJ, Li J, Dong X, Baccei ML. Development and characterization of a Gucy2d-cre mouse to selectively manipulate a subset of inhibitory spinal dorsal horn interneurons. PLoS One 2024; 19:e0300282. [PMID: 38483883 PMCID: PMC10939219 DOI: 10.1371/journal.pone.0300282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 02/24/2024] [Indexed: 03/17/2024] Open
Abstract
Recent transcriptomic studies identified Gucy2d (encoding guanylate cyclase D) as a highly enriched gene within inhibitory dynorphin interneurons in the mouse spinal dorsal horn. To facilitate investigations into the role of the Gucy2d+ population in somatosensation, Gucy2d-cre transgenic mice were created to permit chemogenetic or optogenetic manipulation of this subset of spinal neurons. Gucy2d-cre mice created via CRISPR/Cas9 genomic knock-in were bred to mice expressing a cre-dependent reporter (either tdTomato or Sun1.GFP fusion protein), and the resulting offspring were characterized. Surprisingly, a much wider population of spinal neurons was labeled by cre-dependent reporter expression than previous mRNA-based studies would suggest. Although the cre-dependent reporter expression faithfully labeled ~75% of cells expressing Gucy2d mRNA in the adult dorsal horn, it also labeled a substantial number of additional inhibitory neurons in which no Gucy2d or Pdyn mRNA was detected. Moreover, cre-dependent reporter was also expressed in various regions of the brain, including the spinal trigeminal nucleus, cerebellum, thalamus, somatosensory cortex, and anterior cingulate cortex. Injection of AAV-CAG-FLEX-tdTomato viral vector into adult Gucy2d-cre mice produced a similar pattern of cre-dependent reporter expression in the spinal cord and brain, which excludes the possibility that the unexpected reporter-labeling of cells in the deep dorsal horn and brain was due to transient Gucy2d expression during early stages of development. Collectively, these results suggest that Gucy2d is expressed in a wider population of cells than previously thought, albeit at levels low enough to avoid detection with commonly used mRNA-based assays. Therefore, it is unlikely that these Gucy2d-cre mice will permit selective manipulation of inhibitory signaling mediated by spinal dynorphin interneurons, but this novel cre driver line may nevertheless be useful to target a broader population of inhibitory spinal dorsal horn neurons.
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Affiliation(s)
- Elizabeth K. Serafin
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Judy J. Yoo
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH, USA
- Medical Scientist Training Program, University of Cincinnati, Cincinnati, OH, USA
| | - Jie Li
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Xinzhong Dong
- Departments of Neuroscience, Neurosurgery and Dermatology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Mark L. Baccei
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH, USA
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5
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Torres-Rodriguez JM, Wilson TD, Singh S, Torruella-Suárez ML, Chaudhry S, Adke AP, Becker JJ, Neugebauer B, Lin JL, Martinez Gonzalez S, Soler-Cedeño O, Carrasquillo Y. The parabrachial to central amygdala pathway is critical to injury-induced pain sensitization in mice. Neuropsychopharmacology 2024; 49:508-520. [PMID: 37542159 PMCID: PMC10789863 DOI: 10.1038/s41386-023-01673-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 06/27/2023] [Accepted: 07/12/2023] [Indexed: 08/06/2023]
Abstract
The spino-ponto-amygdaloid pathway is a major ascending circuit relaying nociceptive information from the spinal cord to the brain. Potentiation of excitatory synaptic transmission in the parabrachial nucleus (PBN) to central amygdala (CeA) pathway has been reported in rodent models of persistent pain. However, the functional significance of this pathway in the modulation of the somatosensory component of pain was recently challenged by studies showing that spinal nociceptive neurons do not target CeA-projecting PBN cells and that manipulations of this pathway have no effect on reflexive-defensive somatosensory responses to peripheral noxious stimulation. Here, we showed that activation of CeA-projecting PBN neurons is critical to increase both stimulus-evoked and spontaneous nociceptive responses following an injury in male and female mice. Using optogenetic-assisted circuit mapping, we confirmed a functional excitatory projection from PBN→CeA that is independent of the genetic or firing identity of CeA cells. We then showed that peripheral noxious stimulation increased the expression of the neuronal activity marker Fos in CeA-projecting PBN neurons and that chemogenetic inactivation of these cells decreased behavioral hypersensitivity in models of neuropathic and inflammatory pain without affecting baseline nociception. Lastly, we showed that chemogenetic activation of CeA-projecting PBN neurons is sufficient to induced bilateral hypersensitivity without injury. Together, our results indicate that the PBN→CeA pathway is a key modulator of pain-related behaviors that can increase reflexive-defensive and affective-motivational responses to somatosensory stimulation in injured states without affecting nociception under normal physiological conditions.
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Affiliation(s)
- Jeitzel M Torres-Rodriguez
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Torri D Wilson
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Sudhuman Singh
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Maria L Torruella-Suárez
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Sarah Chaudhry
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Anisha P Adke
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Jordan J Becker
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Benjamin Neugebauer
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Jenny L Lin
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Santiago Martinez Gonzalez
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Omar Soler-Cedeño
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Yarimar Carrasquillo
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA.
- National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD, USA.
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6
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Bell AM, Utting C, Dickie AC, Kucharczyk MW, Quillet R, Gutierrez-Mecinas M, Razlan AN, Cooper AH, Lan Y, Hachisuka J, Weir GA, Bannister K, Watanabe M, Kania A, Hoon MA, Macaulay IC, Denk F, Todd AJ. Deep sequencing of Phox2a nuclei reveals five classes of anterolateral system neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.20.553715. [PMID: 37786726 PMCID: PMC10541585 DOI: 10.1101/2023.08.20.553715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
The anterolateral system (ALS) is a major ascending pathway from the spinal cord that projects to multiple brain areas and underlies the perception of pain, itch and skin temperature. Despite its importance, our understanding of this system has been hampered by the considerable functional and molecular diversity of its constituent cells. Here we use fluorescence-activated cell sorting to isolate ALS neurons belonging to the Phox2a-lineage for single-nucleus RNA sequencing. We reveal five distinct clusters of ALS neurons (ALS1-5) and document their laminar distribution in the spinal cord using in situ hybridization. We identify 3 clusters of neurons located predominantly in laminae I-III of the dorsal horn (ALS1-3) and two clusters with cell bodies located in deeper laminae (ALS4 & ALS5). Our findings reveal the transcriptional logic that underlies ALS neuronal diversity in the adult mouse and uncover the molecular identity of two previously identified classes of projection neurons. We also show that these molecular signatures can be used to target groups of ALS neurons using retrograde viral tracing. Overall, our findings provide a valuable resource for studying somatosensory biology and targeting subclasses of ALS neurons.
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Affiliation(s)
- Andrew M. Bell
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
- School of Biodiversity, One Health and Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | | | - Allen C. Dickie
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Mateusz W. Kucharczyk
- The Wolfson Centre for Age-Related Diseases, King’s College London, London WC2R 2LS, UK
- Laboratory of Neurophysiology, Department of Biochemical Toxicology, Faculty of Pharmacy, Jagiellonian University Medical College, PL30-668 Krakow, Poland
| | - Raphaëlle Quillet
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Maria Gutierrez-Mecinas
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Aimi N.B. Razlan
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Andrew H. Cooper
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | | | - Junichi Hachisuka
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Greg A. Weir
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Kirsty Bannister
- The Wolfson Centre for Age-Related Diseases, King’s College London, London WC2R 2LS, UK
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo 060-8638, Japan
| | - Artur Kania
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, QC, H2W 1R7, Canada
| | - Mark A. Hoon
- Molecular Genetics Section, National Institute of Dental and Craniofacial Research/NIH, Bethesda, MD, USA
| | | | - Franziska Denk
- The Wolfson Centre for Age-Related Diseases, King’s College London, London WC2R 2LS, UK
| | - Andrew J. Todd
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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7
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Li J, Serafin EK, Baccei ML. Intrinsic and synaptic properties of adult mouse spinoperiaqueductal gray neurons and the influence of neonatal tissue damage. Pain 2023; 164:905-917. [PMID: 36149785 PMCID: PMC10033328 DOI: 10.1097/j.pain.0000000000002787] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 09/09/2022] [Indexed: 11/26/2022]
Abstract
ABSTRACT The periaqueductal gray (PAG) represents a key target of projection neurons residing in the spinal dorsal horn. In comparison to lamina I spinoparabrachial neurons, little is known about the intrinsic and synaptic properties governing the firing of spino-PAG neurons, or whether such activity is modulated by neonatal injury. In this study, this issue was addressed using ex vivo whole-cell patch clamp recordings from lamina I spino-PAG neurons in adult male and female FVB mice after hindpaw incision at postnatal day (P)3. Spino-PAG neurons were classified as high output, medium output, or low output based on their action potential discharge after dorsal root stimulation. The high-output subgroup exhibited prevalent spontaneous burst firing and displayed initial burst or tonic patterns of intrinsic firing, whereas low-output neurons showed little spontaneous activity. Interestingly, the level of dorsal root-evoked firing significantly correlated with the resting potential and membrane resistance but not with the strength of primary afferent-mediated glutamatergic drive. Neonatal incision failed to alter the pattern of monosynaptic sensory input, with most spino-PAG neurons receiving direct connections from low-threshold C-fibers. Furthermore, primary afferent-evoked glutamatergic input and action potential discharge in adult spino-PAG neurons were unaltered by neonatal surgical injury. Finally, Hebbian long-term potentiation at sensory synapses, which significantly increased afferent-evoked firing, was similar between P3-incised and naive littermates. Collectively, these data suggest that the functional response of lamina I spino-PAG neurons to sensory input is largely governed by their intrinsic membrane properties and appears resistant to the persistent influence of neonatal tissue damage.
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Affiliation(s)
- Jie Li
- Department of Anesthesiology, Pain Research Center, University of Cincinnati Medical Center, Cincinnati, OH, United States
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8
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Torres-Rodriguez JM, Wilson TD, Singh S, Chaudhry S, Adke AP, Becker JJ, Lin JL, Martinez Gonzalez S, Soler-Cedeño O, Carrasquillo Y. The parabrachial to central amygdala circuit is a key mediator of injury-induced pain sensitization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.08.527340. [PMID: 36945586 PMCID: PMC10028796 DOI: 10.1101/2023.02.08.527340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The spino-ponto-amygdaloid pathway is a major ascending circuit relaying nociceptive information from the spinal cord to the brain. Potentiation of excitatory synaptic transmission in the parabrachial nucleus (PbN) to central amygdala (CeA) pathway has been reported in rodent models of persistent pain. At the behavioral level, the PbN→CeA pathway has been proposed to serve as a general alarm system to potential threats that modulates pain-related escape behaviors, threat memory, aversion, and affective-motivational (but not somatosensory) responses to painful stimuli. Increased sensitivity to previously innocuous somatosensory stimulation is a hallmark of chronic pain. Whether the PbN→CeA circuit contributes to heightened peripheral sensitivity following an injury, however, remains unknown. Here, we demonstrate that activation of CeA-projecting PbN neurons contributes to injury-induced behavioral hypersensitivity but not baseline nociception in male and female mice. Using optogenetic assisted circuit mapping, we confirmed a functional excitatory projection from PbN→CeA that is independent of the genetic or firing identity of CeA cells. We then showed that peripheral noxious stimulation increases the expression of the neuronal activity marker c-Fos in CeA-projecting PbN neurons and chemogenetic inactivation of these cells reduces behavioral hypersensitivity in models of neuropathic and inflammatory pain without affecting baseline nociception. Lastly, we show that chemogenetic activation of CeA-projecting PbN neurons is sufficient to induce bilateral hypersensitivity without injury. Together, our results demonstrate that the PbN→CeA pathway is a key modulator of pain-related behaviors that can amplify responses to somatosensory stimulation in pathological states without affecting nociception under normal physiological conditions. Significance Statement Early studies identified the spino-ponto-amygdaloid pathway as a major ascending circuit conveying nociceptive inputs from the spinal cord to the brain. The functional significance of this circuit to injury-induced hypersensitivity, however, remains unknown. Here, we addressed this gap in knowledge using viral-mediated anatomical tracers, ex-vivo electrophysiology and chemogenetic intersectional approaches in rodent models of persistent pain. We found that activation of this pathway contributes to injury-induced hypersensitivity, directly demonstrating a critical function of the PbN→CeA circuit in pain modulation.
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Affiliation(s)
| | - Torri D. Wilson
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | - Sudhuman Singh
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | - Sarah Chaudhry
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | - Anisha P. Adke
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | - Jordan J. Becker
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | - Jenny L. Lin
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | | | - Omar Soler-Cedeño
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | - Yarimar Carrasquillo
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
- National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD, United States
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9
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Albisetti GW, Ganley RP, Pietrafesa F, Werynska K, Magalhaes de Sousa M, Sipione R, Scheurer L, Bösl MR, Pelczar P, Wildner H, Zeilhofer HU. Inhibitory Kcnip2 neurons of the spinal dorsal horn control behavioral sensitivity to environmental cold. Neuron 2023; 111:92-105.e5. [PMID: 36323322 PMCID: PMC9831669 DOI: 10.1016/j.neuron.2022.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 08/16/2022] [Accepted: 10/04/2022] [Indexed: 11/12/2022]
Abstract
Proper sensing of ambient temperature is of utmost importance for the survival of euthermic animals, including humans. While considerable progress has been made in our understanding of temperature sensors and transduction mechanisms, the higher-order neural circuits processing such information are still only incompletely understood. Using intersectional genetics in combination with circuit tracing and functional neuron manipulation, we identified Kcnip2-expressing inhibitory (Kcnip2GlyT2) interneurons of the mouse spinal dorsal horn as critical elements of a neural circuit that tunes sensitivity to cold. Diphtheria toxin-mediated ablation of these neurons increased cold sensitivity without affecting responses to other somatosensory modalities, while their chemogenetic activation reduced cold and also heat sensitivity. We also show that Kcnip2GlyT2 neurons become activated preferentially upon exposure to cold temperatures and subsequently inhibit spinal nociceptive output neurons that project to the lateral parabrachial nucleus. Our results thus identify a hitherto unknown spinal circuit that tunes cold sensitivity.
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Affiliation(s)
- Gioele W. Albisetti
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Robert P. Ganley
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Francesca Pietrafesa
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Karolina Werynska
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | | | - Rebecca Sipione
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Louis Scheurer
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Michael R. Bösl
- Institute of Experimental Biomedicine I, University Hospital Würzburg, and Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Pawel Pelczar
- Center for Transgenic Models, University of Basel, 4001 Basel, Switzerland
| | - Hendrik Wildner
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland,Corresponding author
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland,Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zürich, 8093 Zürich, Switzerland,Center for Neuroscience Zurich (ZNZ), 8057 Zürich, Switzerland,Drug Discovery Network Zurich (DDNZ), 8057 Zürich, Switzerland,Corresponding author
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10
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Warwick C, Salsovic J, Hachisuka J, Smith KM, Sheahan TD, Chen H, Ibinson J, Koerber HR, Ross SE. Cell type-specific calcium imaging of central sensitization in mouse dorsal horn. Nat Commun 2022; 13:5199. [PMID: 36057681 PMCID: PMC9440908 DOI: 10.1038/s41467-022-32608-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 08/08/2022] [Indexed: 01/12/2023] Open
Abstract
Allodynia is a state in which pain is elicited by innocuous stimuli. Capsaicin applied to the skin results in an allodynia that extends to a broad region beyond the application site. This sensitization is thought to be mediated by spinal networks; however, we do not have a clear picture of which spinal neurons mediate this phenomenon. To address this gap, we used two-photon calcium imaging of excitatory interneurons and spinal projection neurons in the mouse spinal dorsal horn. To distinguish among neuronal subtypes, we developed CICADA, a cell profiling approach to identify cell types during calcium imaging. We then identified capsaicin-responsive and capsaicin-sensitized neuronal populations. Capsaicin-sensitized neurons showed emergent responses to innocuous input and increased receptive field sizes consistent with psychophysical reports. Finally, we identified spinal output neurons that showed enhanced responses from innocuous input. These experiments provide a population-level view of central sensitization and a framework with which to model somatosensory integration in the dorsal horn.
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Affiliation(s)
- Charles Warwick
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA
| | - Joseph Salsovic
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA
| | - Junichi Hachisuka
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA
- Spinal Cord Group, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
| | - Kelly M Smith
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tayler D Sheahan
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA
| | - Haichao Chen
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA
- School of Medicine, Tsinghua University, Beijing, China
| | - James Ibinson
- Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - H Richard Koerber
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA.
| | - Sarah E Ross
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA.
- Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA, USA.
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11
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Spinal ascending pathways for somatosensory information processing. Trends Neurosci 2022; 45:594-607. [PMID: 35701247 DOI: 10.1016/j.tins.2022.05.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 04/19/2022] [Accepted: 05/14/2022] [Indexed: 12/27/2022]
Abstract
The somatosensory system processes diverse types of information including mechanical, thermal, and chemical signals. It has an essential role in sensory perception and body movement and, thus, is crucial for organism survival. The neural network for processing somatosensory information comprises multiple key nodes. Spinal projection neurons represent the key node for transmitting somatosensory information from the periphery to the brain. Although the anatomy of spinal ascending pathways has been characterized, the mechanisms underlying somatosensory information processing by spinal ascending pathways are incompletely understood. Recent studies have begun to reveal the diversity of spinal ascending pathways and their functional roles in somatosensory information processing. Here, we review the anatomic, molecular, and functional characteristics of spinal ascending pathways.
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12
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Wang H, Chen W, Dong Z, Xing G, Cui W, Yao L, Zou WJ, Robinson HL, Bian Y, Liu Z, Zhao K, Luo B, Gao N, Zhang H, Ren X, Yu Z, Meixiong J, Xiong WC, Mei L. A novel spinal neuron connection for heat sensation. Neuron 2022; 110:2315-2333.e6. [PMID: 35561677 DOI: 10.1016/j.neuron.2022.04.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 03/14/2022] [Accepted: 04/19/2022] [Indexed: 12/30/2022]
Abstract
Heat perception enables acute avoidance responses to prevent tissue damage and maintain body thermal homeostasis. Unlike other modalities, how heat signals are processed in the spinal cord remains unclear. By single-cell gene profiling, we identified ErbB4, a transmembrane tyrosine kinase, as a novel marker of heat-sensitive spinal neurons in mice. Ablating spinal ErbB4+ neurons attenuates heat sensation. These neurons receive monosynaptic inputs from TRPV1+ nociceptors and form excitatory synapses onto target neurons. Activation of ErbB4+ neurons enhances the heat response, while inhibition reduces the heat response. We showed that heat sensation is regulated by NRG1, an activator of ErbB4, and it involves dynamic activity of the tyrosine kinase that promotes glutamatergic transmission. Evidence indicates that the NRG1-ErbB4 signaling is also engaged in hypersensitivity of pathological pain. Together, these results identify a spinal neuron connection consisting of ErbB4+ neurons for heat sensation and reveal a regulatory mechanism by the NRG1-ErbB4 signaling.
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Affiliation(s)
- Hongsheng Wang
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Wenbing Chen
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Zhaoqi Dong
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Guanglin Xing
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Wanpeng Cui
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Lingling Yao
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Wen-Jun Zou
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Heath L Robinson
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Yaoyao Bian
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Zhipeng Liu
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Kai Zhao
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Bin Luo
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Nannan Gao
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Hongsheng Zhang
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Xiao Ren
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Zheng Yu
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - James Meixiong
- Solomon H. Snyder Department of Neuroscience and Medical Scientist Training Program, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Wen-Cheng Xiong
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH 44106, USA
| | - Lin Mei
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH 44106, USA.
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13
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Skorput AGJ, Gore R, Schorn R, Riedl MS, Marron Fernandez de Velasco E, Hadlich B, Kitto KF, Fairbanks CA, Vulchanova L. Targeting the somatosensory system with AAV9 and AAV2retro viral vectors. PLoS One 2022; 17:e0264938. [PMID: 35271639 PMCID: PMC8912232 DOI: 10.1371/journal.pone.0264938] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 02/19/2022] [Indexed: 12/17/2022] Open
Abstract
Adeno-associated viral (AAV) vectors allow for site-specific and time-dependent genetic manipulation of neurons. However, for successful implementation of AAV vectors, major consideration must be given to the selection of viral serotype and route of delivery for efficient gene transfer into the cell type being investigated. Here we compare the transduction pattern of neurons in the somatosensory system following injection of AAV9 or AAV2retro in the parabrachial complex of the midbrain, the spinal cord dorsal horn, the intrathecal space, and the colon. Transduction was evaluated based on Cre-dependent expression of tdTomato in transgenic reporter mice, following delivery of AAV9 or AAV2retro carrying identical constructs that drive the expression of Cre/GFP. The pattern of distribution of tdTomato expression indicated notable differences in the access of the two AAV serotypes to primary afferent neurons via peripheral delivery in the colon and to spinal projections neurons via intracranial delivery within the parabrachial complex. Additionally, our results highlight the superior sensitivity of detection of neuronal transduction based on reporter expression relative to expression of viral products.
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Affiliation(s)
- Alexander G. J. Skorput
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Reshma Gore
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Rachel Schorn
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Maureen S. Riedl
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota, United States of America
| | | | - Bailey Hadlich
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Kelley F. Kitto
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Carolyn A. Fairbanks
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota, United States of America
- Department of Pharmacology, Medical School, University of Minnesota, Minneapolis, Minnesota, United States of America
- Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Lucy Vulchanova
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota, United States of America
- * E-mail:
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14
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Kókai É, Alsulaiman WAA, Dickie AC, Bell AM, Goffin L, Watanabe M, Gutierrez-Mecinas M, Todd AJ. Characterisation of deep dorsal horn projection neurons in the spinal cord of the Phox2a::Cre mouse line. Mol Pain 2022; 18:17448069221119614. [PMID: 36000342 PMCID: PMC9445510 DOI: 10.1177/17448069221119614] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 07/20/2022] [Accepted: 07/27/2022] [Indexed: 11/16/2022] Open
Abstract
Projection neurons belonging to the anterolateral system (ALS) underlie the perception of pain, skin temperature and itch. Many ALS cells are located in laminae III-V of the dorsal horn and the adjacent lateral white matter. However, relatively little is known about the excitatory synaptic input to these deep ALS cells, and therefore about their engagement with the neuronal circuitry of the region. We have used a recently developed mouse line, Phox2a::Cre, to investigate a population of deep dorsal horn ALS neurons known as "antenna cells", which are characterised by dense innervation from peptidergic nociceptors, and to compare these with other ALS cells in the deep dorsal horn and lateral white matter. We show that these two classes differ, both in the density of excitatory synapses, and in the source of input at these synapses. Peptidergic nociceptors account for around two-thirds of the excitatory synapses on the antenna cells, but for only a small proportion of the input to the non-antenna cells. Conversely, boutons with high levels of VGLUT2, which are likely to originate mainly from glutamatergic spinal neurons, account for only ∼5% of the excitatory synapses on antenna cells, but for a much larger proportion of the input to the non-antenna cells. VGLUT1 is expressed by myelinated low-threshold mechanoreceptors and corticospinal axons, and these innervate both antenna and non-antenna cells. However, the density of VGLUT1 input to the non-antenna cells is highly variable, consistent with the view that these neurons are functionally heterogeneous.
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Affiliation(s)
- Éva Kókai
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Wafa AA Alsulaiman
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Allen C Dickie
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Andrew M Bell
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Luca Goffin
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo, Japan
| | - Maria Gutierrez-Mecinas
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Andrew J Todd
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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15
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Characterisation of lamina I anterolateral system neurons that express Cre in a Phox2a-Cre mouse line. Sci Rep 2021; 11:17912. [PMID: 34504158 PMCID: PMC8429737 DOI: 10.1038/s41598-021-97105-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/10/2021] [Indexed: 11/13/2022] Open
Abstract
A recently developed Phox2a::Cre mouse line has been shown to capture anterolateral system (ALS) projection neurons. Here, we used this line to test whether Phox2a-positive cells represent a distinct subpopulation among lamina I ALS neurons. We show that virtually all lamina I Phox2a cells can be retrogradely labelled from injections targeted on the lateral parabrachial area (LPb), and that most of those in the cervical cord also belong to the spinothalamic tract. Phox2a cells accounted for ~ 50–60% of the lamina I cells retrogradely labelled from LPb or thalamus. Phox2a was preferentially associated with smaller ALS neurons, and with those showing relatively weak neurokinin 1 receptor expression. The Phox2a cells were also less likely to project to the ipsilateral LPb. Although most Phox2a cells phosphorylated extracellular signal-regulated kinases following noxious heat stimulation, ~ 20% did not, and these were significantly smaller than the activated cells. This suggests that those ALS neurons that respond selectively to skin cooling, which have small cell bodies, may be included among the Phox2a population. Previous studies have defined neurochemical populations among the ALS cells, based on expression of Tac1 or Gpr83. However, we found that the proportions of Phox2a cells that expressed these genes were similar to the proportions reported for all lamina I ALS neurons, suggesting that Phox2a is not differentially expressed among cells belonging to these populations. Finally, we used a mouse line that resulted in membrane labelling of the Phox2a cells and showed that they all possess dendritic spines, although at a relatively low density. However, the distribution of the postsynaptic protein Homer revealed that dendritic spines accounted for a minority of the excitatory synapses on these cells. Our results confirm that Phox2a-positive cells in lamina I are ALS neurons, but show that the Phox2a::Cre line preferentially captures specific types of ALS cells.
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16
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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: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [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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17
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Gucy2d selectively marks inhibitory dynorphin neurons in the spinal dorsal horn but is dispensable for pain and itch sensitivity. Pain Rep 2021; 6:e947. [PMID: 34296052 PMCID: PMC8291471 DOI: 10.1097/pr9.0000000000000947] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 06/08/2021] [Indexed: 11/26/2022] Open
Abstract
Introduction Inhibitory neurons in the spinal dorsal horn can be classified based on expression of neurochemical marker genes. However, these marker genes are often expressed throughout the central nervous system, which poses challenges for manipulating genetically identified spinal neurons without undesired off-target effects. Objectives We investigated whether Gucy2d, previously identified as a highly selective marker of dynorphin-lineage neurons in the dorsal horn, is expressed in other locations within the adult mouse spinal cord, dorsal root ganglia (DRG), or brain. In addition, we sought to molecularly characterize Gucy2d-expressing dorsal horn neurons and investigate whether the disruption of Gucy2d gene expression affects sensitivity to itch or pain. Methods In situ hybridization experiments assessed Gucy2d mRNA expression in the adult mouse spinal cord, DRG, and brain, and its colocalization with Pax2, Bhlhb5, and Pde2a in dorsal horn neurons. Knockout mice lacking Gucy2d expression were compared with littermate controls to assess sensitivity to chloroquine-induced itch and dry skin-mediated chronic itch, as well as heat, cold, or mechanical stimuli. Results Gucy2d is selectively expressed in dynorphin-lineage neurons in lamina I-III of the adult mouse spinal cord but not in the brain or DRG. Spinal Gucy2d-expressing neurons are inhibitory neurons that also express the transcription factor Bhlhb5 and the cGMP-dependent phosphodiesterase Pde2a. Gucy2d knockout mice did not exhibit altered responses to itch or pain. Conclusions The selective expression of Gucy2d within a subpopulation of inhibitory dorsal horn neurons may yield a means to selectively manipulate inhibitory signaling at the level of the spinal cord without effects on the brain.
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18
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Wercberger R, Braz JM, Weinrich JA, Basbaum AI. Pain and itch processing by subpopulations of molecularly diverse spinal and trigeminal projection neurons. Proc Natl Acad Sci U S A 2021; 118:e2105732118. [PMID: 34234018 PMCID: PMC8285968 DOI: 10.1073/pnas.2105732118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
A remarkable molecular and functional heterogeneity of the primary sensory neurons and dorsal horn interneurons transmits pain- and or itch-relevant information, but the molecular signature of the projection neurons that convey the messages to the brain is unclear. Here, using retro-TRAP (translating ribosome affinity purification) and RNA sequencing, we reveal extensive molecular diversity of spino- and trigeminoparabrachial projection neurons. Among the many genes identified, we highlight distinct subsets of Cck+ -, Nptx2+ -, Nmb+ -, and Crh+ -expressing projection neurons. By combining in situ hybridization of retrogradely labeled neurons with Fos-based assays, we also demonstrate significant functional heterogeneity, including both convergence and segregation of pain- and itch-provoking inputs into molecularly diverse subsets of NK1R- and non-NK1R-expressing projection neurons.
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Affiliation(s)
- Racheli Wercberger
- Department of Anatomy, University of California, San Francisco, CA 94158
| | - Joao M Braz
- Department of Anatomy, University of California, San Francisco, CA 94158
| | - Jarret A Weinrich
- Department of Anatomy, University of California, San Francisco, CA 94158
| | - Allan I Basbaum
- Department of Anatomy, University of California, San Francisco, CA 94158
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19
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Browne TJ, Smith KM, Gradwell MA, Iredale JA, Dayas CV, Callister RJ, Hughes DI, Graham BA. Spinoparabrachial projection neurons form distinct classes in the mouse dorsal horn. Pain 2021; 162:1977-1994. [PMID: 33779126 PMCID: PMC8208100 DOI: 10.1097/j.pain.0000000000002194] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 12/16/2020] [Accepted: 12/21/2020] [Indexed: 11/29/2022]
Abstract
ABSTRACT Projection neurons in the spinal dorsal horn relay sensory information to higher brain centres. The activation of these populations is shaped by afferent input from the periphery, descending input from the brain, and input from local interneuron circuits. Much of our recent understanding of dorsal horn circuitry comes from studies in transgenic mice; however, information on projection neurons is still based largely on studies in monkey, cat, and rat. We used viral labelling to identify and record from mouse parabrachial nucleus (PBN) projecting neurons located in the dorsal horn of spinal cord slices. Overall, mouse lamina I spinoparabrachial projection neurons (SPBNs) exhibit many electrophysiological and morphological features that overlap with rat. Unbiased cluster analysis distinguished 4 distinct subpopulations of lamina I SPBNs, based on their electrophysiological properties that may underlie different sensory signalling features in each group. We also provide novel information on SPBNs in the deeper lamina (III-V), which have not been previously studied by patch clamp analysis. These neurons exhibited higher action potential discharge frequencies and received weaker excitatory synaptic input than lamina I SPBNs, suggesting this deeper population produces different sensory codes destined for the PBN. Mouse SPBNs from both regions (laminae I and III-V) were often seen to give off local axon collaterals, and we provide neuroanatomical evidence they contribute to excitatory input to dorsal horn circuits. These data provide novel information to implicate excitatory input from parabrachial projection neuron in dorsal horn circuit activity during processing of nociceptive information, as well as defining deep dorsal horn projection neurons that provide an alternative route by which sensory information can reach the PBN.
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Affiliation(s)
- Tyler J. Browne
- School of Biomedical Sciences and Pharmacy, Faculty of Health, University of Newcastle, Callaghan, New South Wales, Australia
- Hunter Medical Research Institute (HMRI), New Lambton Heights, New South Wales, Australia
| | - Kelly M. Smith
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Mark A. Gradwell
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, United States
- W.M. Keck Center for Collaborative Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, United States
| | - Jacqueline A. Iredale
- School of Biomedical Sciences and Pharmacy, Faculty of Health, University of Newcastle, Callaghan, New South Wales, Australia
- Hunter Medical Research Institute (HMRI), New Lambton Heights, New South Wales, Australia
| | - Christopher V. Dayas
- School of Biomedical Sciences and Pharmacy, Faculty of Health, University of Newcastle, Callaghan, New South Wales, Australia
- Hunter Medical Research Institute (HMRI), New Lambton Heights, New South Wales, Australia
| | - Robert J. Callister
- School of Biomedical Sciences and Pharmacy, Faculty of Health, University of Newcastle, Callaghan, New South Wales, Australia
- Hunter Medical Research Institute (HMRI), New Lambton Heights, New South Wales, Australia
| | - David I. Hughes
- Institute of Neuroscience Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Brett A. Graham
- School of Biomedical Sciences and Pharmacy, Faculty of Health, University of Newcastle, Callaghan, New South Wales, Australia
- Hunter Medical Research Institute (HMRI), New Lambton Heights, New South Wales, Australia
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20
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Abstract
Inhibitory interneurons in the adult spinal dorsal horn (DH) can be neurochemically classified into subpopulations that regulate distinct somatosensory modalities. Although inhibitory networks in the rodent DH undergo dramatic remodeling over the first weeks of life, little is known about the maturation of identified classes of GABAergic interneurons, or whether their role in somatosensation shifts during development. We investigated age-dependent changes in the connectivity and function of prodynorphin (DYN)-lineage neurons in the mouse DH that suppress mechanosensation and itch during adulthood. In vitro patch clamp recordings revealed a developmental increase in primary afferent drive to DYN interneurons and a transition from exclusive C-fiber monosynaptic input to mixed A-fiber and C-fiber innervation. Although most adult DYN interneurons exhibited tonic firing as expected from their inhibitory phenotype, neonatal and adolescent DYN cells were predominantly classified as phasic or single-spiking. Importantly, we also found that most of the inhibitory presynaptic terminals contacting lamina I spinoparabrachial projection neurons (PNs) originate from DYN neurons. Furthermore, inhibitory synaptic input from DYN interneurons onto PNs was weaker during the neonatal period, likely reflecting a lower number of GABAergic terminals and a reduced probability of GABA release compared to adults. Finally, spinal DYN interneurons attenuated mechanical sensitivity throughout development, but this population dampened acute nonhistaminergic itch only during adulthood. Collectively, these findings suggest that the spinal "gates" controlling sensory transmission to the brain may emerge in a modality-selective manner during early life due to the postnatal tuning of inhibitory synaptic circuits within the DH.
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21
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Spinal Inhibitory Interneurons: Gatekeepers of Sensorimotor Pathways. Int J Mol Sci 2021; 22:ijms22052667. [PMID: 33800863 PMCID: PMC7961554 DOI: 10.3390/ijms22052667] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 02/26/2021] [Accepted: 03/04/2021] [Indexed: 12/20/2022] Open
Abstract
The ability to sense and move within an environment are complex functions necessary for the survival of nearly all species. The spinal cord is both the initial entry site for peripheral information and the final output site for motor response, placing spinal circuits as paramount in mediating sensory responses and coordinating movement. This is partly accomplished through the activation of complex spinal microcircuits that gate afferent signals to filter extraneous stimuli from various sensory modalities and determine which signals are transmitted to higher order structures in the CNS and to spinal motor pathways. A mechanistic understanding of how inhibitory interneurons are organized and employed within the spinal cord will provide potential access points for therapeutics targeting inhibitory deficits underlying various pathologies including sensory and movement disorders. Recent studies using transgenic manipulations, neurochemical profiling, and single-cell transcriptomics have identified distinct populations of inhibitory interneurons which express an array of genetic and/or neurochemical markers that constitute functional microcircuits. In this review, we provide an overview of identified neural components that make up inhibitory microcircuits within the dorsal and ventral spinal cord and highlight the importance of inhibitory control of sensorimotor pathways at the spinal level.
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22
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Nguyen E, Lim G, Ding H, Hachisuka J, Ko MC, Ross SE. Morphine acts on spinal dynorphin neurons to cause itch through disinhibition. Sci Transl Med 2021; 13:13/579/eabc3774. [DOI: 10.1126/scitranslmed.abc3774] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 08/13/2020] [Indexed: 12/18/2022]
Abstract
Morphine-induced itch is a very common and debilitating side effect that occurs in laboring women who receive epidural analgesia and in patients who receive spinal morphine for relief of perioperative pain. Although antihistamines are still widely prescribed for the treatment of morphine-induced itch, their use is controversial because the cellular basis for morphine-induced itch remains unclear. Here, we used animal models and show that neuraxial morphine causes itch through neurons and not mast cells. In particular, we found that spinal dynorphin (Pdyn) neurons are both necessary and sufficient for morphine-induced itch in mice. Agonism of the kappa-opioid receptor alleviated morphine-induced itch in mice and nonhuman primates. Thus, our findings not only reveal that morphine causes itch through a mechanism of disinhibition but also challenge the long-standing use of antihistamines, thereby informing the treatment of millions worldwide.
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Affiliation(s)
- Eileen Nguyen
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
- Medical Scientist Training Program, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Grace Lim
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Huiping Ding
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Junichi Hachisuka
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
| | - Mei-Chuan Ko
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Sarah E. Ross
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
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23
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Serafin EK, Paranjpe A, Brewer CL, Baccei ML. Single-nucleus characterization of adult mouse spinal dynorphin-lineage cells and identification of persistent transcriptional effects of neonatal hindpaw incision. Pain 2021; 162:203-218. [PMID: 33045156 PMCID: PMC7744314 DOI: 10.1097/j.pain.0000000000002007] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Neonatal tissue damage can have long-lasting effects on nociceptive processing in the central nervous system, which may reflect persistent injury-evoked alterations to the normal balance between synaptic inhibition and excitation in the spinal dorsal horn. Spinal dynorphin-lineage (pDyn) neurons are part of an inhibitory circuit which limits the flow of nociceptive input to the brain and is disrupted by neonatal tissue damage. To identify the potential molecular underpinnings of this disruption, an unbiased single-nucleus RNAseq analysis of adult mouse spinal pDyn cells characterized this population in depth and then identified changes in gene expression evoked by neonatal hindpaw incision. The analysis revealed 11 transcriptionally distinct subpopulations (ie, clusters) of dynorphin-lineage cells, including both inhibitory and excitatory neurons. Investigation of injury-evoked differential gene expression identified 15 genes that were significantly upregulated or downregulated in adult pDyn neurons from neonatally incised mice compared with naive littermate controls, with both cluster-specific and pan-neuronal transcriptional changes observed. Several of the identified genes, such as Oxr1 and Fth1 (encoding ferritin), were related to the cellular stress response. However, the relatively low number of injury-evoked differentially expressed genes also suggests that posttranscriptional regulation within pDyn neurons may play a key role in the priming of developing nociceptive circuits by early-life injury. Overall, the findings reveal novel insights into the molecular heterogeneity of a key population of dorsal horn interneurons that has previously been implicated in the suppression of mechanical pain and itch.
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Affiliation(s)
- Elizabeth K Serafin
- Department of Anesthesiology, Pain Research Center, University of Cincinnati Medical Center, Cincinnati, OH, United States . Dr. Brewer is now with the Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, United States
| | - Aditi Paranjpe
- Division of Biomedical Informatics, Bioinformatics Collaborative Services, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - Chelsie L Brewer
- Department of Anesthesiology, Pain Research Center, University of Cincinnati Medical Center, Cincinnati, OH, United States . Dr. Brewer is now with the Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, United States
- Neuroscience Graduate Program, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Mark L Baccei
- Department of Anesthesiology, Pain Research Center, University of Cincinnati Medical Center, Cincinnati, OH, United States . Dr. Brewer is now with the Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, United States
- Neuroscience Graduate Program, University of Cincinnati College of Medicine, Cincinnati, OH, United States
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24
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Harding EK, Fung SW, Bonin RP. Insights Into Spinal Dorsal Horn Circuit Function and Dysfunction Using Optical Approaches. Front Neural Circuits 2020; 14:31. [PMID: 32595458 PMCID: PMC7303281 DOI: 10.3389/fncir.2020.00031] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 05/01/2020] [Indexed: 12/13/2022] Open
Abstract
Somatosensation encompasses a variety of essential modalities including touch, pressure, proprioception, temperature, pain, and itch. These peripheral sensations are crucial for all types of behaviors, ranging from social interaction to danger avoidance. Somatosensory information is transmitted from primary afferent fibers in the periphery into the central nervous system via the dorsal horn of the spinal cord. The dorsal horn functions as an intermediary processing center for this information, comprising a complex network of excitatory and inhibitory interneurons as well as projection neurons that transmit the processed somatosensory information from the spinal cord to the brain. It is now known that there can be dysfunction within this spinal cord circuitry in pathological pain conditions and that these perturbations contribute to the development and maintenance of pathological pain. However, the complex and heterogeneous network of the spinal dorsal horn has hampered efforts to further elucidate its role in somatosensory processing. Emerging optical techniques promise to illuminate the underlying organization and function of the dorsal horn and provide insights into the role of spinal cord sensory processing in shaping the behavioral response to somatosensory input that we ultimately observe. This review article will focus on recent advances in optogenetics and fluorescence imaging techniques in the spinal cord, encompassing findings from both in vivo and in vitro preparations. We will also discuss the current limitations and difficulties of employing these techniques to interrogate the spinal cord and current practices and approaches to overcome these challenges.
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Affiliation(s)
- Erika K Harding
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Samuel Wanchi Fung
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada
| | - Robert P Bonin
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada.,University of Toronto Centre for the Study of Pain, University of Toronto, Toronto, ON, Canada
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25
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Neonatal Injury Evokes Persistent Deficits in Dynorphin Inhibitory Circuits within the Adult Mouse Superficial Dorsal Horn. J Neurosci 2020; 40:3882-3895. [PMID: 32291327 DOI: 10.1523/jneurosci.0029-20.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 03/18/2020] [Accepted: 04/04/2020] [Indexed: 12/22/2022] Open
Abstract
Neonatal tissue damage induces long-term deficits in inhibitory synaptic transmission within the spinal superficial dorsal horn (SDH) that include a reduction in primary afferent-evoked, feedforward inhibition onto adult projection neurons. However, the subpopulations of mature GABAergic interneurons which are compromised by early-life injury have yet to be identified. The present research illuminates the persistent effects of neonatal surgical injury on the function of inhibitory SDH interneurons derived from the prodynorphin (DYN) lineage, a population that synapses directly onto lamina I spinoparabrachial neurons and is known to suppress mechanical pain and itch in adults. The results demonstrate that hindpaw incision at postnatal day 3 (P3) significantly decreased the strength of primary afferent-evoked glutamatergic drive onto DYN neurons within the adult mouse SDH while increasing the appearance of afferent-evoked inhibition onto the same population. Neonatal injury also dampened the intrinsic membrane excitability of mature DYN neurons, and reduced their action potential discharge in response to sensory input, compared with naive littermate controls. Furthermore, P3 incision decreased the efficacy of inhibitory DYN synapses onto adult spinoparabrachial neurons, which reflected a prolonged reduction in the probability of GABA release. Collectively, the data suggest that early-life tissue damage may persistently constrain the ability of spinal DYN interneurons to limit ascending nociceptive transmission to the adult brain. This is predicted to contribute to the loss of feedforward inhibition onto mature projection neurons, and the "priming" of nociceptive circuits in the developing spinal cord, following injuries during the neonatal period.SIGNIFICANCE STATEMENT Neonatal injury has lasting effects on pain processing in the adult CNS, including a reduction in feedforward inhibition onto ascending projection neurons in the spinal dorsal horn. While it is clear that spinal GABAergic interneurons are comprised of multiple subpopulations that play distinct roles in somatosensation, the identity of those interneurons which are compromised by tissue damage during early life remains unknown. Here we document persistent deficits in spinal inhibitory circuits involving dynorphin-lineage interneurons previously implicated in gating mechanical pain and itch. Notably, neonatal injury reduced the strength of dynorphin-lineage inhibitory synapses onto mature lamina I spinoparabrachial neurons, a major output of the spinal nociceptive network, which could contribute to the priming of pain pathways by early tissue damage.
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