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The Journal of Physiology - 2023 - Goodlich - Blockade of 5‐HT2 receptors suppresses motor unit firing and estimates of2.55 MB
Published VersionCC BY V4.0, Open Access
Journal article
Blockade of 5‐HT2 receptors suppresses motor unit firing and estimates of persistent inward currents during voluntary muscle contraction in humans
The Journal of Physiology, Vol.601(6), pp.1121-1138
2023
PMID: 36790076
Abstract
Serotonergic neuromodulation contributes to enhanced voluntary muscle activation. However, it is not known how the likely motoneurone receptor candidate (5-HT2) influences the firing rate and activation threshold of motor units (MUs) in humans. The purpose of this study was to determine whether 5-HT2 receptor activity contributes to human MU behaviour during voluntary ramped contractions of differing intensity. High-density surface EMG (HDsEMG) of the tibialis anterior was assessed during ramped isometric dorsiflexions at 10, 30, 50 and 70% of maximal voluntary contraction (MVC). MU characteristics were successfully extracted from HDsEMG of 11 young adults (four female) pre- and post-ingestion of 8 mg cyproheptadine or a placebo. Antagonism of 5-HT2 receptors caused a reduction in MU discharge rate during steady-state muscle activation that was independent of the level of contraction intensity [P < 0.001; estimated mean difference (∆) = 1.06 pulses/s], in addition to an increase in MU derecruitment threshold (P < 0.013, ∆ = 1.23% MVC), without a change in force during MVC (P = 0.652). A reduction in estimates of persistent inward current amplitude was observed at 10% MVC (P < 0.001, ∆ = 0.99 Hz) and 30% MVC (P = 0.003, ∆ = 0.75 Hz) that aligned with 5-HT changes in MU firing behaviour attributable to 5-HT2 antagonism. Overall, these findings indicate that 5-HT2 receptor activity has a role in regulating the discharge rate in populations of spinal motoneurones when performing voluntary contractions. This study provides evidence of a direct link between MU discharge properties, persistent inward current activity and 5-HT2 receptor activity in humans.
Details
- Title
- Blockade of 5‐HT2 receptors suppresses motor unit firing and estimates of persistent inward currents during voluntary muscle contraction in humans
- Authors
- Benjamin I. Goodlich (Corresponding Author) - Griffith UniversityAlessandro Del Vecchio - Friedrich-Alexander-Universität Erlangen-NürnbergSean A. Horan - Griffith UniversityJustin J. Kavanagh - Griffith University
- Publication details
- The Journal of Physiology, Vol.601(6), pp.1121-1138
- Publisher
- Wiley-Blackwell Publishing Ltd.
- Date published
- 2023
- DOI
- 10.1113/JP284164
- ISSN
- 1469-7793; 0022-3751
- PMID
- 36790076
- Copyright note
- © 2023 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
- Data Availability
- The data that support the findings of this study are available on request from the corresponding author.
- Organisation Unit
- School of Health - Sports & Exercise Science
- Language
- English
- Record Identifier
- 991081292302621
- Output Type
- Journal article
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web Of Science research areas
- Neurosciences
- Physiology