Influence of serotonin on the long-term muscle contraction of the Kohnstamm phenomenon

Influence of serotonin on the long-term muscle contraction of the Kohnstamm phenomenon | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Influence of serotonin on the long-term muscle contraction of the Kohnstamm phenomenon Annika Schmidt, Tobias Meindl, Alin Albu-Schäffer, David W. Franklin, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5423708/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 13 May, 2025 Read the published version in Scientific Reports → Version 1 posted 10 You are reading this latest preprint version Abstract Neuromodulation plays a central role in human movement control. An imbalance of neurotransmitters, especially dopamine and serotonin, can be associated with various neurological disorders causing tremors or spasms. Specifically, serotonin was shown to scale motoneuron excitability following intense muscle contractions, affecting short-latency reflexes. Likely, it may also influence motoneuron modulation in prolonged contractions, although this lacks experimental evidence. An intriguing test case for this hypothesis is presented by the Kohnstamm phenomenon, where sustained muscle contractions lead to prolonged amplified EMG activity and involuntary motions, aligning with the timescale of serotonergic amplification. The suspected serotonin influence on this effect was tested in a placebo-controlled human user study with 14 participants, where half were administered the serotonin antagonist Cyproheptadine and the other half a placebo. Comparing EMG and force responses after inducing the Kohnstamm phenomenon in the deltoid muscles, revealed statistically significant faster EMG decay with the serotonin antagonist, while decay remained consistent in the placebo group compared to the response of the same participant group without medication. The force measurements showed the same trend, although no significance. This provides new data-based evidence that serotonin contributes to long-term motoneuron modulation, extending previous findings about the dedicated role and influence of this neurotransmitter. Biological sciences/Neuroscience/Motor control Biological sciences/Neuroscience/Neuronal physiology/Excitability Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 13 May, 2025 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 17 Feb, 2025 Reviews received at journal 15 Feb, 2025 Reviewers agreed at journal 26 Jan, 2025 Reviews received at journal 26 Jan, 2025 Reviewers agreed at journal 09 Jan, 2025 Reviewers invited by journal 26 Nov, 2024 Editor assigned by journal 26 Nov, 2024 Editor invited by journal 22 Nov, 2024 Submission checks completed at journal 21 Nov, 2024 First submitted to journal 09 Nov, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5423708","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":376144143,"identity":"2367bbe2-edba-4fe2-b695-c394c2e18133","order_by":0,"name":"Annika Schmidt","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5ElEQVRIiWNgGAWjYJCCgw0gUoKB4QAPgw1jH4RNtJaENMY2YrQwwrQw8CQcJqyFf3bvwYMzahjs+Wd3Jx54++O8bJv0AcYbH/BokbhzLuHghmMMiTPunN1wcE7CbeM2vgRmyxn4rLmRY3DwARtDgoFE7obDPAm3E9t4GNikefDokAdr+cdgD9VyDqLlDx4tBiAtG9sYGDdAtByAaMHnLkOQlpl9EokzbuQC/ZKWbNzGw9hs2YNHi9yNHOOPPd9s7Pln5G7+8MbGTrafh/ngjR/4rIEAlIiAxNMoGAWjYBSMAgoAANldU1NXOxcrAAAAAElFTkSuQmCC","orcid":"","institution":"Technical University of Munich (TUM)","correspondingAuthor":true,"prefix":"","firstName":"Annika","middleName":"","lastName":"Schmidt","suffix":""},{"id":376144144,"identity":"cf32a96d-95b9-459d-81d9-490ddfecedf2","order_by":1,"name":"Tobias Meindl","email":"","orcid":"","institution":"Technical University of Munich (TUM)","correspondingAuthor":false,"prefix":"","firstName":"Tobias","middleName":"","lastName":"Meindl","suffix":""},{"id":376144145,"identity":"445a206e-8f2b-4b25-af8d-b8dbd3b9a521","order_by":2,"name":"Alin Albu-Schäffer","email":"","orcid":"","institution":"Technical University of Munich (TUM)","correspondingAuthor":false,"prefix":"","firstName":"Alin","middleName":"","lastName":"Albu-Schäffer","suffix":""},{"id":376144146,"identity":"046c391f-e907-40c1-9f56-27f0f46ec220","order_by":3,"name":"David W. 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