Journal article
Blockade of 5-HT2 receptors suppresses rate of torque development and motor unit discharge rate during rapid contractions
Journal of Neurophysiology, Vol.127(1), pp.150-160
2022
PMID: 34936830
Abstract
Serotonin (5-HT) is a neuromodulator that is critical for regulating the excitability of spinal motoneurons and the generation of muscle torque. However, the role of 5-HT in modulating human motor unit activity during rapid contractions has yet to be assessed. Nine healthy participants (23.7 ± 2.2 yr) ingested 8 mg of the competitive 5-HT2 antagonist cyproheptadine in a double-blinded, placebo-controlled, repeated-measures experiment. Rapid dorsiflexion contractions were performed at 30%, 50%, and 70% of maximal voluntary contraction (MVC), where motor unit activity was assessed by high-density surface electromyographic decomposition. A second protocol was performed where a sustained, fatigue-inducing dorsiflexion contraction was completed before undertaking the same 30%, 50%, and 70% MVC rapid contractions and motor unit analysis. Motor unit discharge rate (P < 0.001) and rate of torque development (RTD; P = 0.019) for the unfatigued muscle were both significantly lower for the cyproheptadine condition. Following the fatigue inducing contraction, cyproheptadine reduced motor unit discharge rate (P < 0.001) and RTD (P = 0.024), whereas the effects of cyproheptadine on motor unit discharge rate and RTD increased with increasing contraction intensity. Overall, these results support the viewpoint that serotonergic effects in the central nervous system occur fast enough to regulate motor unit discharge rate during rapid powerful contractions.
Details
- Title
- Blockade of 5-HT2 receptors suppresses rate of torque development and motor unit discharge rate during rapid contractions
- Authors
- Benjamin Goodlich (Corresponding Author) - Griffith UniversitySean A. Horan - Griffith UniversityJustin J. Kavanagh - Griffith University
- Publication details
- Journal of Neurophysiology, Vol.127(1), pp.150-160
- Publisher
- American Physiological Society
- Date published
- 2022
- DOI
- 10.1152/jn.00470.2021
- ISSN
- 1522-1598
- PMID
- 34936830
- Organisation Unit
- School of Health - Sports & Exercise Science
- Language
- English
- Record Identifier
- 991081292202621
- Output Type
- Journal article
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