Calretinin positive neurons form an excitatory amplifier network in the spinal cord dorsal horn

Abstract

Nociceptive information is relayed through the spinal cord dorsal horn, a critical area in sensory processing. The neuronal circuits in this region that underpin sensory perception must be clarified to better understand how dysfunction can lead to pathological pain. This study used an optogenetic approach to selectively activate spinal interneurons that express the calcium-binding protein calretinin (CR). We show that these interneurons form an interconnected network that can initiate and sustain enhanced excitatory signaling, and directly relay signals to lamina I projection neurons. Photoactivation of CR interneurons in vivo resulted in a significant nocifensive behavior that was morphine sensitive, caused a conditioned place aversion, and was enhanced by spared nerve injury. Furthermore, halorhodopsin-mediated inhibition of these interneurons elevated sensory thresholds. Our results suggest that dorsal horn circuits that involve excitatory CR neurons are important for the generation and amplification of pain and identify these interneurons as a future analgesic target.

Data availability

All data generated or analysed during this study are included in the manuscript and supporting files.

Article and author information

Author details

  1. Kelly M Smith

    School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-3039-5002
  2. Tyler J Browne

    School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia
    Competing interests
    The authors declare that no competing interests exist.
  3. Olivia C Davis

    Institute of Neuroscience Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-8792-7324
  4. A Coyle

    Institute of Neuroscience Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  5. Kieran A Boyle

    Institute of Neuroscience Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  6. Masahiko Watanabe

    Department of Anatomy, Hokkaido University School of Medicine, Sapporo, Japan
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-5037-7138
  7. Sally A Dickinson

    School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia
    Competing interests
    The authors declare that no competing interests exist.
  8. Jacqueline A Iredale

    School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia
    Competing interests
    The authors declare that no competing interests exist.
  9. Mark A Gradwell

    School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia
    Competing interests
    The authors declare that no competing interests exist.
  10. Phillip Jobling

    School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia
    Competing interests
    The authors declare that no competing interests exist.
  11. Robert J Callister

    School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia
    Competing interests
    The authors declare that no competing interests exist.
  12. Christopher V Dayas

    School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia
    For correspondence
    christopher.dayas@newcastle.edu.au
    Competing interests
    The authors declare that no competing interests exist.
  13. David I Hughes

    Institute of Neuroscience Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
    For correspondence
    David.I.Hughes@glasgow.ac.uk
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-1260-3362
  14. Brett A Graham

    School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia
    For correspondence
    brett.graham@newcastle.edu.au
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-8070-0503

Funding

National Health and Medical Research Council (631000)

  • Robert J Callister
  • Brett A Graham

National Health and Medical Research Council (1043933)

  • Robert J Callister
  • David I Hughes
  • Brett A Graham

Biotechnology and Biological Sciences Research Council (BB/J000620/1)

  • David I Hughes

Biotechnology and Biological Sciences Research Council (BB/P007996/1)

  • David I Hughes

National Health and Medical Research Council (1144638)

  • Robert J Callister
  • Christopher V Dayas
  • David I Hughes
  • Brett A Graham

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Allan Basbaum, University of California, San Francisco, United States

Ethics

Animal experimentation: All studies carried out in Glasgow were in accordance with the European Community directive 86/609/EEC and UK Animals (Scientific Procedures) Act 1986. All studies carried out at University of Newcastle were in accordance with the Animal Research Act 1985 (NSW), under the guidelines of the National Health and Medical Research Council Code for the Care and Use of Animals for Scientific Purposes in Australia (2013). All animal handling and experimental procedures were performed under approved institutional animal care and ethics committee protocols (University of Newcastle: A-2013-312 and A2016-603; University of Glasgow)

Version history

  1. Received: June 10, 2019
  2. Accepted: November 9, 2019
  3. Accepted Manuscript published: November 12, 2019 (version 1)
  4. Version of Record published: December 12, 2019 (version 2)

Copyright

© 2019, Smith et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Kelly M Smith
  2. Tyler J Browne
  3. Olivia C Davis
  4. A Coyle
  5. Kieran A Boyle
  6. Masahiko Watanabe
  7. Sally A Dickinson
  8. Jacqueline A Iredale
  9. Mark A Gradwell
  10. Phillip Jobling
  11. Robert J Callister
  12. Christopher V Dayas
  13. David I Hughes
  14. Brett A Graham
(2019)
Calretinin positive neurons form an excitatory amplifier network in the spinal cord dorsal horn
eLife 8:e49190.
https://doi.org/10.7554/eLife.49190

Share this article

https://doi.org/10.7554/eLife.49190

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