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Synaptic mechanisms underlying modulation of locomotor-related motoneuron output by premotor cholinergic interneurons

  1. Filipe Nascimento
  2. Matthew James Broadhead
  3. Efstathia Tetringa
  4. Eirini Tsape
  5. Laskaro Zagoraiou
  6. Gareth Miles  Is a corresponding author
  1. University of St Andrews, United Kingdom
  2. Biomedical Research Foundation of the Academy of Athens, Greece
Research Article
  • Cited 2
  • Views 1,614
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Cite this article as: eLife 2020;9:e54170 doi: 10.7554/eLife.54170

Abstract

Spinal motor networks are formed by diverse populations of interneurons that set the strength and rhythmicity of behaviors such as locomotion. A small cluster of cholinergic interneurons, expressing the transcription factor Pitx2, modulates the intensity of muscle activation via 'C-bouton' inputs to motoneurons. However, the synaptic mechanisms underlying this neuromodulation remain unclear. Here, we confirm in mice that Pitx2+ interneurons are active during fictive locomotion and that their chemogenetic inhibition reduces the amplitude of motor output. Furthermore, after genetic ablation of cholinergic Pitx2+ interneurons, M2 receptor-dependent regulation of the intensity of locomotor output is lost. Conversely, chemogenetic stimulation of Pitx2+ interneurons leads to activation of M2 receptors on motoneurons, regulation of Kv2.1 channels and greater motoneuron output due to an increase in the inter-spike afterhyperpolarization and a reduction in spike half-width. Our findings elucidate synaptic mechanisms by which cholinergic spinal interneurons modulate the final common pathway for motor output.

Data availability

All of the data presented in this study are included in the manuscript and supporting files

Article and author information

Author details

  1. Filipe Nascimento

    School of Psychology and Neuroscience, University of St Andrews, St Andrews, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-9426-2807
  2. Matthew James Broadhead

    School of Psychology and Neuroscience, University of St Andrews, St Andrews, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-4078-5581
  3. Efstathia Tetringa

    Center of Basic Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
    Competing interests
    The authors declare that no competing interests exist.
  4. Eirini Tsape

    Center of Basic Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
    Competing interests
    The authors declare that no competing interests exist.
  5. Laskaro Zagoraiou

    Center of Basic Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
    Competing interests
    The authors declare that no competing interests exist.
  6. Gareth Miles

    School of Psychology and Neuroscience, University of St Andrews, St Andrews, United Kingdom
    For correspondence
    gbm4@st-andrews.ac.uk
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-8624-4625

Funding

Alfred Dunhil Links Foundation

  • Filipe Nascimento

Biotechnology and Biological Sciences Research Council (BB/M021793/1)

  • Matthew James Broadhead
  • Gareth Miles

Foundation Sante

  • Eirini Tsape
  • Laskaro Zagoraiou

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

Ethics

Animal experimentation: All the procedures performed on animals were conducted in accordance with the UK Animals (Scientific Procedures) Act 1986 and were approved by the University of St Andrews Animal Welfare Ethics Committee. Experiments on animals performed in the Biomedical Research Foundation of the Academy of Athens were approved by the competent veterinary service of the Prefecture of Athens, Greece in accordance with the existing legal framework. The facility is registered as a 'breeding' and 'user' establishment by the Veterinary Service of the Prefecture of Athens according to the Presidential Decree 56/2013 in harmonization with the European Directive 2010/63/EU for the protection of animals used for scientific purposes.

Reviewing Editor

  1. Claire Wyart, Institut du Cerveau et la Moelle épinière, Hôpital Pitié-Salpêtrière, Sorbonne Universités, UPMC Univ Paris 06, Inserm, CNRS, France

Publication history

  1. Received: December 4, 2019
  2. Accepted: February 20, 2020
  3. Accepted Manuscript published: February 21, 2020 (version 1)
  4. Version of Record published: March 9, 2020 (version 2)

Copyright

© 2020, Nascimento 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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