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Mavanji V, Pomonis BL, Shekels L, Kotz CM. Interactions between Lateral Hypothalamic Orexin and Dorsal Raphe Circuitry in Energy Balance. Brain Sci 2024; 14:464. [PMID: 38790443 PMCID: PMC11117928 DOI: 10.3390/brainsci14050464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 04/30/2024] [Accepted: 05/04/2024] [Indexed: 05/26/2024] Open
Abstract
Orexin/hypocretin terminals innervate the dorsal raphe nucleus (DRN), which projects to motor control areas important for spontaneous physical activity (SPA) and energy expenditure (EE). Orexin receptors are expressed in the DRN, and obesity-resistant (OR) rats show higher expression of these receptors in the DRN and elevated SPA/EE. We hypothesized that orexin-A in the DRN enhances SPA/EE and that DRN-GABA modulates the effect of orexin-A on SPA/EE. We manipulated orexin tone in the DRN either through direct injection of orexin-A or through the chemogenetic activation of lateral-hypothalamic (LH) orexin neurons. In the orexin neuron activation experiment, fifteen minutes prior to the chemogenetic activation of orexin neurons, the mice received either the GABA-agonist muscimol or antagonist bicuculline injected into the DRN, and SPA/EE was monitored for 24 h. In a separate experiment, orexin-A was injected into the DRN to study the direct effect of DRN orexin on SPA/EE. We found that the activation of orexin neurons elevates SPA/EE, and manipulation of GABA in the DRN does not alter the SPA response to orexin neuron activation. Similarly, intra-DRN orexin-A enhanced SPA and EE in the mice. These results suggest that orexin-A in the DRN facilitates negative energy balance by increasing physical activity-induced EE, and that modulation of DRN orexin-A is a potential strategy to promote SPA and EE.
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Affiliation(s)
- Vijayakumar Mavanji
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Brianna L. Pomonis
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Laurie Shekels
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Catherine M. Kotz
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
- Geriatric Research, Education and Clinical Center, Minneapolis VA Health Care System, Minneapolis, MN 55417, USA
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2
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Orssatto LBR, Thorstensen JR, Scott D, Daly RM. Are we underestimating the potential of neuroactive drugs to augment neuromotor function in sarcopenia? Metabolism 2024; 154:155816. [PMID: 38364901 DOI: 10.1016/j.metabol.2024.155816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 02/01/2024] [Accepted: 02/09/2024] [Indexed: 02/18/2024]
Affiliation(s)
- Lucas B R Orssatto
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Faculty of Health, Deakin University, Geelong, Australia.
| | - Jacob R Thorstensen
- Faculty of Health Sciences & Medicine, Bond University, Gold Coast, Australia; School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, Australia
| | - David Scott
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Faculty of Health, Deakin University, Geelong, Australia; School of Clinical Sciences at Monash Health, Monash University, Clayton, Australia
| | - Robin M Daly
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Faculty of Health, Deakin University, Geelong, Australia
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3
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Shi C, Liang Z, Li T, Hao Q, Xiang H, Xie Q. Metabolome and microbiome analyses of the anti-fatigue mechanism of Acanthopanax senticosus leaves. Food Funct 2024; 15:3791-3809. [PMID: 38511300 DOI: 10.1039/d3fo05311c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
Acanthopanax senticosus leaves, widely used as a vegetable and tea, are reported to be beneficial in treating neurological disorders. At present, their anti-fatigue effect remains to be established. In this study, we analyzed the composition of the extracts from A. senticosus leaves and confirmed their antioxidant and anti-inflammatory properties at the cellular level. In mice subjected to exhaustive running on a treadmill, supplementation with A. senticosus leaf extracts enhanced exercise performance and alleviated fatigue via the reversal of exercise-induced 5-HT elevation, metabolic waste accumulation, organ damage, and glucose metabolism-related gene expression. The collective findings from microbiome and metabolomic analyses indicate that A. senticosus leaf extracts increase α-diversity, regulate microbial composition, and reverse exercise-mediated disruption of carbohydrate, creatine, amino acid, and trimethylamine metabolism. This study provides preliminary evidence for the utility of A. senticosus leaves as a promising anti-fatigue food and offers insights into the underlying mechanism.
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Affiliation(s)
- Chao Shi
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, P.R. China.
- School of Life Sciences, Jilin University, Changchun 130012, P.R. China
| | - Zehua Liang
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, P.R. China.
- School of Life Sciences, Jilin University, Changchun 130012, P.R. China
| | - Ting Li
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, P.R. China.
- School of Life Sciences, Jilin University, Changchun 130012, P.R. China
| | - Qi Hao
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, P.R. China.
- School of Life Sciences, Jilin University, Changchun 130012, P.R. China
| | - Hongyu Xiang
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, P.R. China.
- School of Life Sciences, Jilin University, Changchun 130012, P.R. China
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, School of Life Sciences, Jilin University, Changchun 130012, P.R. China
- Institute of Changbai Mountain Resource and Health, Jilin University, Fusong 134504, P.R. China
| | - Qiuhong Xie
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, P.R. China.
- School of Life Sciences, Jilin University, Changchun 130012, P.R. China
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, School of Life Sciences, Jilin University, Changchun 130012, P.R. China
- Institute of Changbai Mountain Resource and Health, Jilin University, Fusong 134504, P.R. China
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Henderson TT, Taylor JL, Thorstensen JR, Kavanagh JJ. Excitatory drive to spinal motoneurones is necessary for serotonin to modulate motoneurone excitability via 5-HT 2 receptors in humans. Eur J Neurosci 2024; 59:17-35. [PMID: 37994250 DOI: 10.1111/ejn.16190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 09/14/2023] [Accepted: 10/25/2023] [Indexed: 11/24/2023]
Abstract
Serotonin modulates corticospinal excitability, motoneurone firing rates and contractile strength via 5-HT2 receptors. However, the effects of these receptors on cortical and motoneurone excitability during voluntary contractions have not been explored in humans. Therefore, the purpose of this study was to investigate how 5-HT2 antagonism affects corticospinal and motoneuronal excitability with and without descending drive to motoneurones. Twelve individuals (aged 24 ± 4 years) participated in a double-blind, placebo-controlled, crossover study, whereby the 5-HT2 antagonist cyproheptadine was administered. Transcranial magnetic stimulation (TMS) was delivered to the motor cortex to produce motor evoked potentials (MEPs), and electrical stimulation at the cervicomedullary junction was used to generate cervicomedullary motor evoked potentials (CMEPs) in the biceps brachii at rest and during a range of submaximal elbow flexions. Evoked potentials were also obtained after a conditioning TMS pulse to produce conditioned MEPs and CMEPs (100 ms inter-stimulus interval). 5-HT2 antagonism reduced maximal torque (p < 0.001), and compared to placebo, reduced unconditioned MEP amplitude at rest (p = 0.003), conditioned MEP amplitude at rest (p = 0.033) and conditioned MEP amplitude during contractions (p = 0.020). 5-HT2 antagonism also increased unconditioned CMEP amplitude during voluntary contractions (p = 0.041) but not at rest. Although 5-HT2 antagonism increased long-interval intracortical inhibition, net corticospinal excitability was unaffected during voluntary contractions. Given that spinal motoneurone excitability was only affected when descending drive to motoneurones was present, the current study indicates that excitatory drive is necessary for 5-HT2 receptors to regulate motoneurone excitability but not intracortical circuits.
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Affiliation(s)
- Tyler T Henderson
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Janet L Taylor
- Centre for Human Performance, School of Medical and Health Sciences, Edith Cowan University, Perth, Australia
- Neuroscience Research Australia, Sydney, Australia
| | - Jacob R Thorstensen
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
| | - Justin J Kavanagh
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
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Thorstensen JR, Henderson TT, Kavanagh JJ. Serotonergic and noradrenergic contributions to motor cortical and spinal motoneuronal excitability in humans. Neuropharmacology 2024; 242:109761. [PMID: 37838337 DOI: 10.1016/j.neuropharm.2023.109761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 10/05/2023] [Accepted: 10/11/2023] [Indexed: 10/16/2023]
Abstract
Animal models indicate that motor behaviour is shaped by monoamine neuromodulators released diffusely throughout the brain and spinal cord. As an alternative to conducting a single study to explore the effects of neuromodulators on the human motor system, we have identified and collated human experiments investigating motor effects of well-characterised drugs that act on serotonergic and noradrenergic networks. In doing so, we present strong neuropharmacology evidence that human motor pathways are affected by neuromodulators across both healthy and clinical populations, insight that cannot be determined from a single reductionist experiment. We have focused our review on the effects that monoaminergic drugs have on muscle responses to non-invasive stimulation of the motor cortex and peripheral nerves, and other closely related tests of motoneuron excitability, and discuss how these measurement techniques elucidate the effects of neuromodulators at motor cortical and spinal motoneuronal levels. Although there is some heterogeneity in study methods, we find drugs acting to enhance extracellular concentrations of serotonin tend to reduce the excitability of the human motor cortex, and enhanced extracellular concentrations of noradrenaline increases motor cortical excitability by enhancing intracortical facilitation and reducing inhibition. Both monoamines tend to enhance the excitability of spinal motoneurons. Overall, this review details the importance of neuromodulators for the output of human motor pathways and suggests that commonly prescribed monoaminergic drugs target the motor system in addition to their typical psychiatric/neurological indications.
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Affiliation(s)
- Jacob R Thorstensen
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia.
| | - Tyler T Henderson
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Justin J Kavanagh
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
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Zhou Y, Chu Z, Luo Y, Yang F, Cao F, Luo F, Lin Q. Dietary Polysaccharides Exert Anti-Fatigue Functions via the Gut-Muscle Axis: Advances and Prospectives. Foods 2023; 12:3083. [PMID: 37628082 PMCID: PMC10453516 DOI: 10.3390/foods12163083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/11/2023] [Accepted: 08/11/2023] [Indexed: 08/27/2023] Open
Abstract
Due to today's fast-paced lifestyle, most people are in a state of sub-health and face "unexplained fatigue", which can seriously affect their health, work efficiency, and quality of life. Fatigue is also a common symptom of several serious diseases such as Parkinson's, Alzheimer's, cancer, etc. However, the contributing mechanisms are not clear, and there are currently no official recommendations for the treatment of fatigue. Some dietary polysaccharides are often used as health care supplements; these have been reported to have specific anti-fatigue effects, with minor side effects and rich pharmacological activities. Dietary polysaccharides can be activated during food processing or during gastrointestinal transit, exerting unique effects. This review aims to comprehensively summarize and evaluate the latest advances in the biological processes of exercise-induced fatigue, to understand dietary polysaccharides and their possible molecular mechanisms in alleviating exercise-induced fatigue, and to systematically elaborate the roles of gut microbiota and the gut-muscle axis in this process. From the perspective of the gut-muscle axis, investigating the relationship between polysaccharides and fatigue will enhance our understanding of fatigue and may lead to a significant breakthrough regarding the molecular mechanism of fatigue. This paper will provide new perspectives for further research into the use of polysaccharides in food science and food nutrition, which could help develop potential anti-fatigue agents and open up novel therapies for sub-health conditions.
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Affiliation(s)
- Yaping Zhou
- National Engineering Research Center of Deep Process of Rice and Byproducts, Hunan Key Laboratory of Grain-Oil Deep Process and Quality Control, College of Food Science and Engineering, Central South University of Forestry and Technology, No. 498, Shaoshan Road, Changsha 410004, China; (Y.Z.); (Z.C.); (F.Y.); (F.L.)
| | - Zhongxing Chu
- National Engineering Research Center of Deep Process of Rice and Byproducts, Hunan Key Laboratory of Grain-Oil Deep Process and Quality Control, College of Food Science and Engineering, Central South University of Forestry and Technology, No. 498, Shaoshan Road, Changsha 410004, China; (Y.Z.); (Z.C.); (F.Y.); (F.L.)
| | - Yi Luo
- Department of Clinical Medicine, Medical College of Xiangya, Central South University, Changsha 410008, China;
| | - Feiyan Yang
- National Engineering Research Center of Deep Process of Rice and Byproducts, Hunan Key Laboratory of Grain-Oil Deep Process and Quality Control, College of Food Science and Engineering, Central South University of Forestry and Technology, No. 498, Shaoshan Road, Changsha 410004, China; (Y.Z.); (Z.C.); (F.Y.); (F.L.)
| | - Fuliang Cao
- Co-Innovation Center for the Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing 210037, China;
| | - Feijun Luo
- National Engineering Research Center of Deep Process of Rice and Byproducts, Hunan Key Laboratory of Grain-Oil Deep Process and Quality Control, College of Food Science and Engineering, Central South University of Forestry and Technology, No. 498, Shaoshan Road, Changsha 410004, China; (Y.Z.); (Z.C.); (F.Y.); (F.L.)
| | - Qinlu Lin
- National Engineering Research Center of Deep Process of Rice and Byproducts, Hunan Key Laboratory of Grain-Oil Deep Process and Quality Control, College of Food Science and Engineering, Central South University of Forestry and Technology, No. 498, Shaoshan Road, Changsha 410004, China; (Y.Z.); (Z.C.); (F.Y.); (F.L.)
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Yunoki T, Zang K, Hatano K, Matsuura R, Ohtsuka Y. Relationship between disturbances of CO 2 homeostasis and force output characteristics during isometric knee extension. Respir Physiol Neurobiol 2023; 315:104119. [PMID: 37468055 DOI: 10.1016/j.resp.2023.104119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Revised: 06/30/2023] [Accepted: 07/14/2023] [Indexed: 07/21/2023]
Abstract
To determine whether disturbances of CO2 homeostasis alter force output characteristics of lower limb muscles, participants performed four isometric knee extension trials (MVC30%, 10s each with 20-s rest intervals) in three CO2 conditions (normocapnia [NORM], hypercapnia [HYPER], and hypocapnia [HYPO]). Respiratory frequency and tidal volume were matched between CO2 conditions. In each MVC30%, the participants exerted a constant force (30% of maximum voluntary contraction [MVC]). The force coefficient of variation (Fcv) during each MVC30% and MVC before and after the four MVC30% trials were measured. For the means of the four trials, Fcv was significantly lower in HYPER than in HYPO. However, within HYPER, a significant positive correlation was found between the increase in end-tidal CO2 partial pressure and the increase in Fcv. MVCs in NORM and HYPO decreased significantly over the four trials, while no such reduction was observed in HYPER. These results suggest that perturbed CO2 homeostasis influences the force output characteristics independently of breathing pattern variables.
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Affiliation(s)
- Takahiro Yunoki
- Department of Health and Physical Education, Graduate School of Education, Hokkaido University, Sapporo, Japan.
| | - Kejun Zang
- Department of Health and Physical Education, Graduate School of Education, Hokkaido University, Sapporo, Japan
| | - Kei Hatano
- Japan Institute of Sports Sciences, Japan
| | - Ryouta Matsuura
- Graduate School of Education, Joetsu University of Education, Japan
| | - Yoshinori Ohtsuka
- Department of Sports and Human Studies, Sapporo International University, Japan
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Marzouk M, McKeown DJ, Borg DN, Headrick J, Kavanagh JJ. Perceptions of fatigue and neuromuscular measures of performance fatigability during prolonged low-intensity elbow flexions. Exp Physiol 2023; 108:465-479. [PMID: 36763088 PMCID: PMC10103868 DOI: 10.1113/ep090981] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 01/24/2023] [Indexed: 02/11/2023]
Abstract
NEW FINDINGS What is the central question of this study? What is the predictive relationship between self-reported scales to quantify perceptions of fatigue during exercise and gold standard measures used to quantify the development of neuromuscular fatigue? What is the main finding and its importance? No scale was determined to be substantively more effective than another. However, the number of ongoing contractions performed was shown to be a better predictor of fatigue in the motor system than any of the subjective scales. ABSTRACT The purpose of this study was to determine the relationship between transcranial magnetic stimulation (TMS) measures of performance fatigability and commonly used scales that quantify perceptions of fatigue during exercise. Twenty healthy participants (age 23 ± 3 years, 10 female) performed 10 submaximal isometric elbow flexions at 20% maximal voluntary contraction (MVC) for 2 min, separated by 45 s of rest. Biceps brachii muscle electromyography and elbow flexion torque responses to single-pulse TMS were obtained at the end of each contraction to assess central factors of performance fatigability. A rating of perceived exertion (RPE) scale, Omnibus Resistance scale, Likert scale, Rating of Fatigue scale and a visual analogue scale (VAS) were used to assess perceptions of fatigue at the end of each contraction. The RPE (root mean square error (RMSE) = 0.144) and Rating of Fatigue (RMSE = 0.145) scales were the best predictors of decline in MVC torque, whereas the Likert (RMSE= 0.266) and RPE (RMSE= 0.268) scales were the best predictors of electromyographic amplitude. Although the Likert (RMSE = 7.6) and Rating of Fatigue (RMSE = 7.6) scales were the best predictors of voluntary muscle activation of any scale, the number of contractions performed during the protocol was a better predictor (RMSE = 7.3). The ability of the scales to predict TMS measures of performance fatigability were in general similar. Interestingly, the number of contractions performed was a better predictor of TMS measures than the scales themselves.
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Affiliation(s)
- Monica Marzouk
- Neural Control of Movement LaboratoryMenzies Health Institute QueenslandGriffith UniversityGold CoastQueenslandAustralia
| | - Daniel J. McKeown
- Neural Control of Movement LaboratoryMenzies Health Institute QueenslandGriffith UniversityGold CoastQueenslandAustralia
| | - David N. Borg
- The Australian Centre for Health Services Innovation and Centre for Healthcare Transformation, School of Public Health and Social WorkQueensland University of TechnologyBrisbaneQueenslandAustralia
| | - Jonathon Headrick
- Neural Control of Movement LaboratoryMenzies Health Institute QueenslandGriffith UniversityGold CoastQueenslandAustralia
| | - Justin J. Kavanagh
- Neural Control of Movement LaboratoryMenzies Health Institute QueenslandGriffith UniversityGold CoastQueenslandAustralia
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Goodlich BI, Del Vecchio A, Horan SA, Kavanagh JJ. Blockade of 5-HT 2 receptors suppresses motor unit firing and estimates of persistent inward currents during voluntary muscle contraction in humans. J Physiol 2023; 601:1121-1138. [PMID: 36790076 DOI: 10.1113/jp284164] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 02/10/2023] [Indexed: 02/16/2023] Open
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. KEY POINTS: Activation of 5-HT receptors on the soma and dendrites of motoneurones regulates their excitability. Previous work using chlorpromazine and cyproheptadine has demonstrated that the 5-HT2 receptor regulates motoneurone activity in humans with chronic spinal cord injury and non-injured control subjects. It is not known how the 5-HT2 receptor directly influences motor unit (MU) discharge and MU recruitment in larger populations of human motoneurones during voluntary contractions of differing intensity. Despite the absence of change in force during maximal voluntary dorsiflexions, 5-HT2 receptor antagonism caused a reduction in MU discharge rate during submaximal steady-state muscle contraction, in addition to an increase in MU derecruitment threshold, irrespective of the submaximal contraction intensity. Reductions in estimates of persistent inward currents after 5-HT2 receptor antagonism support the viewpoint that the 5-HT2 receptor plays a crucial role in regulating motor activity, whereby a persistent inward current-based mechanism is involved in regulating the excitability of human motoneurones.
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Affiliation(s)
- Benjamin I Goodlich
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
| | - Alessandro Del Vecchio
- Department of Artificial Intelligence in Biomedical Engineering, Friedrich-Alexander University (FAU), Erlangen-Nuremberg, Erlangen, Germany
| | - Sean A Horan
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
| | - Justin J Kavanagh
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
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Mackay Phillips K, Orssatto LBR, Polman R, Van der Pols JC, Trajano GS. The effects of α-lactalbumin supplementation and handgrip contraction on soleus motoneuron excitability. Eur J Appl Physiol 2023; 123:395-404. [PMID: 36443491 DOI: 10.1007/s00421-022-05101-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 11/16/2022] [Indexed: 12/03/2022]
Abstract
INTRODUCTION We tested two strategies that hypothetically increase serotonin availability (α-lactalbumin consumption and a remote submaximal handgrip contraction) on estimates of persistent inward currents (PICs) amplitude of soleus muscle in healthy participants. METHODS With a randomised, double-blind, and cross-over design, 13 healthy participants performed triangular-shaped ramp contractions with their plantar flexors (20% of maximal torque), followed by a 30-s handgrip sustained contraction (40% of maximal force) and consecutive repeated triangular-shaped contractions. This was performed before and after the consumption of either 40 g of α-lactalbumin, an isonitrogenous beverage (Zein) or an isocaloric beverage (Corn-starch). Soleus motor units discharge rates were analysed from high-density surface electromyography signals. PICs were estimated by calculating the delta frequency (ΔF) of motor unit train spikes using the paired motor unit technique. RESULTS ΔF (0.19 pps; p = 0.001; d = 0.30) and peak discharge rate (0.20 pps; p < 0.001; d = 0.37) increased after the handgrip contraction, irrespective of the consumed supplement. No effects of α-lactalbumin were observed. CONCLUSIONS Our results indicate that 40 g of α-lactalbumin was unable to modify intrinsic motoneuron excitability. However, performing a submaximal handgrip contraction before the plantar flexion triangular contraction was capable of increasing ΔF and discharge rates on soleus motor units. These findings highlight the diffused effects of serotonergic input, its effects on motoneuron discharge behaviour, and suggest a cross-effector effect within human motoneurons.
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Affiliation(s)
- Karen Mackay Phillips
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), 149 Victoria Park Rd, Kelvin Grove, Brisbane, QLD, 4059, Australia.
| | - Lucas B R Orssatto
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), 149 Victoria Park Rd, Kelvin Grove, Brisbane, QLD, 4059, Australia
| | - Remco Polman
- Institute of Health and Wellbeing, Federation University, Berwick, Australia
| | - Jolieke C Van der Pols
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), 149 Victoria Park Rd, Kelvin Grove, Brisbane, QLD, 4059, Australia
| | - Gabriel S Trajano
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), 149 Victoria Park Rd, Kelvin Grove, Brisbane, QLD, 4059, Australia
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Amann M, Sidhu SK, McNeil CJ, Gandevia SC. Critical considerations of the contribution of the corticomotoneuronal pathway to central fatigue. J Physiol 2022; 600:5203-5214. [PMID: 36326193 PMCID: PMC9772161 DOI: 10.1113/jp282564] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022] Open
Abstract
Neural drive originating in higher brain areas reaches exercising limb muscles through the corticospinal-motoneuronal pathway, which links the motor cortex and spinal motoneurones. The properties of this pathway have frequently been observed to change during fatiguing exercise in ways that could influence the development of central fatigue (i.e. the progressive reduction in voluntary muscle activation). However, based on differences in motor cortical and motoneuronal excitability between exercise modalities (e.g. single-joint vs. locomotor exercise), there is no characteristic response that allows for a categorical conclusion about the effect of these changes on functional impairments and performance limitations. Despite the lack of uniformity in findings during fatigue, there is strong evidence for marked 'inhibition' of motoneurones as a direct result of voluntary drive. Endogenous forms of neuromodulation, such as via serotonin released from neurones, can directly affect motoneuronal output and central fatigue. Exogenous forms of neuromodulation, such as brain stimulation, may achieve a similar effect, although the evidence is weak. Non-invasive transcranial direct current stimulation can cause transient or long-lasting changes in cortical excitability; however, variable results across studies cast doubt on its claimed capacity to enhance performance. Furthermore, with these studies, it is difficult to establish a cause-and-effect relationship between brain responsiveness and exercise performance. This review briefly summarizes changes in the corticomotoneuronal pathway during various types of exercise, and considers the relevance of these changes for the development of central fatigue, as well as the potential of non-invasive brain stimulation to enhance motor cortical excitability, motoneuronal output and, ultimately, exercise performance.
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Affiliation(s)
- Markus Amann
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Simranjit K. Sidhu
- School of Biomedicine, The University of Adelaide, South Australia, Australia
| | - Chris J McNeil
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - Simon C Gandevia
- Neuroscience Research Australia and University of New South Wales, Sydney, Australia
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12
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Pethick J, Tallent J. The Neuromuscular Fatigue-Induced Loss of Muscle Force Control. Sports (Basel) 2022; 10:184. [PMID: 36422953 PMCID: PMC9694672 DOI: 10.3390/sports10110184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 11/14/2022] [Accepted: 11/17/2022] [Indexed: 11/22/2022] Open
Abstract
Neuromuscular fatigue is characterised not only by a reduction in the capacity to generate maximal muscle force, but also in the ability to control submaximal muscle forces, i.e., to generate task-relevant and precise levels of force. This decreased ability to control force is quantified according to a greater magnitude and lower complexity (temporal structure) of force fluctuations, which are indicative of decreased force steadiness and adaptability, respectively. The "loss of force control" is affected by the type of muscle contraction used in the fatiguing exercise, potentially differing between typical laboratory tests of fatigue (e.g., isometric contractions) and the contractions typical of everyday and sporting movements (e.g., dynamic concentric and eccentric contractions), and can be attenuated through the use of ergogenic aids. The loss of force control appears to relate to a fatigue-induced increase in common synaptic input to muscle, though the extent to which various mechanisms (afferent feedback, neuromodulatory pathways, cortical/reticulospinal pathways) contribute to this remains to be determined. Importantly, this fatigue-induced loss of force control could have important implications for task performance, as force control is correlated with performance in a range of tasks that are associated with activities of daily living, occupational duties, and sporting performance.
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Affiliation(s)
- Jamie Pethick
- School of Sport, Rehabilitation and Exercise Sciences, University of Essex, Colchester CO4 3SQ, UK
| | - Jamie Tallent
- School of Sport, Rehabilitation and Exercise Sciences, University of Essex, Colchester CO4 3SQ, UK
- Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Science, Monash University, Melbourne 3800, Australia
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13
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Zhu H, Wang C, Cheng Y, Guo Y, Qian H, Liu Y. Brassica rapa L. (Tibetan turnip) prevents sleep-deprivation induced cognitive deficits via the inhibition of neuroinflammation and mitochondrial depolarization. Food Funct 2022; 13:10610-10622. [PMID: 36168843 DOI: 10.1039/d2fo02649j] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Brassica rapa L., an edible, feeding and medicinal plant cultivated on the Tibetan plateau with altitudes above 3800 m, has several pharmacological effects. However, its therapeutic effects against memory impairment and central fatigue have yet to be conclusively established. In this study, the Y-maze and Morris water maze tasks revealed that Brassica rapa L. aqueous extract (BE) significantly ameliorated cognitive deficits of sleep deprivation (SD)-treated mice. Moreover, BE treatment partially alleviated SD-induced reductions in the levels of peripheral energy metabolism, and significantly decreased inflammatory factor levels in serum and hippocampus. In addition, BE treatment significantly relieved central fatigue and stabilized the excitability as well as activities of neurons by regulating the levels of hypothalamus tryptophan metabolites and striatum neurotransmitters. The neuroprotective effects of BE were also confirmed using glutamate-treated HT22 cells, whereby BE pretreatment significantly attenuated intracellular ROS production and mitochondrial depolarization via adenosine 5'-monophosphate activated protein kinase/peroxisome proliferators-activated receptors (AMPK/PPAR-γ) signaling pathways. Thus, BE might probably prevent SD-induced learning and memory deficits by inhibiting neuroinflammation and restoring mitochondrial energy metabolism in the hippocampus. These findings imply that BE is a potential complementary therapy for those suffering from deficient sleep or neurometabolic disorders, although this needs verification by prospective clinical studies.
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Affiliation(s)
- Hongkang Zhu
- State Key Laboratory of Food Science and Technology, Jiangnan University, China. .,Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, Jiangnan University, China.,School of Food Science and Technology, Jiangnan University, No. 1800 Lihu Avenue, Wuxi, Jiangsu Province, 214122, China
| | - Cheng Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, China. .,Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, Jiangnan University, China.,School of Food Science and Technology, Jiangnan University, No. 1800 Lihu Avenue, Wuxi, Jiangsu Province, 214122, China
| | - Yuliang Cheng
- State Key Laboratory of Food Science and Technology, Jiangnan University, China. .,Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, Jiangnan University, China.,School of Food Science and Technology, Jiangnan University, No. 1800 Lihu Avenue, Wuxi, Jiangsu Province, 214122, China
| | - Yahui Guo
- State Key Laboratory of Food Science and Technology, Jiangnan University, China. .,Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, Jiangnan University, China.,School of Food Science and Technology, Jiangnan University, No. 1800 Lihu Avenue, Wuxi, Jiangsu Province, 214122, China
| | - He Qian
- State Key Laboratory of Food Science and Technology, Jiangnan University, China. .,Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, Jiangnan University, China.,School of Food Science and Technology, Jiangnan University, No. 1800 Lihu Avenue, Wuxi, Jiangsu Province, 214122, China
| | - Yu Liu
- Wuxi 9th People's Hospital Affiliated to Soochow University, China.
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14
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Henderson TT, Taylor JL, Thorstensen JR, Tucker MG, Kavanagh JJ. Enhanced availability of serotonin limits muscle activation during high-intensity, but not low-intensity, fatiguing contractions. J Neurophysiol 2022; 128:751-762. [PMID: 36001790 DOI: 10.1152/jn.00182.2022] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Serotonin (5-HT) modulates motoneuron excitability during muscle contractions, where the release of 5-HT in the central nervous system (CNS) is linked to the intensity of physical activity. Although there is evidence that enhanced availability of 5-HT can exacerbate fatigue, these effects on the development of fatigue during different contraction intensities are largely unknown. The purpose of this study was to investigate how enhanced 5-HT availability affects voluntary muscle activation and corticospinal excitability during fatigue-inducing contractions. Two experiments were performed. In the first experiment (n = 11), twelve isometric elbow flexions at 20% maximal voluntary contractions (MVC) were performed for 2-min each with 40-s rest periods. In the second experiment (n = 14), twelve maximal isometric elbow flexions were held for 10-s each with 40-s rest periods. In both experiments, the selective serotonin reuptake inhibitor (20 mg paroxetine), or a placebo, was administered in a two-way crossover-design. Muscle responses to transcranial magnetic stimulation (TMS) of the motor cortex (both experiments 1 and 2), as well as motor point stimulation of the elbow flexors (experiment 2) were assessed. Paroxetine reduced both motor cortical (p = 0.018) and motor point voluntary activation (p = 0.036) during the maximal contraction protocol. Paroxetine also reduced exercise-induced lengthening of the TMS silent period during the submaximal (p = 0.037) and maximal (p = 0.002) contraction protocols. Activation of inhibitory 5-HT1A receptors on motoneurons likely exacerbated exercise-induced reductions in voluntarily drive to the elbow flexors. However, 5-HT modulation of motor activity also appeared at the supraspinal level.
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Affiliation(s)
- Tyler T Henderson
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Janet L Taylor
- School of Medical and Health Sciences, Edith Cowan University, Perth, Australia.,Neuroscience Research Australia, Sydney, Australia
| | - Jacob R Thorstensen
- Child Health Research Centre, The University of Queensland, Brisbane, Australia
| | - Murray G Tucker
- Barwon Health, University Hospital Geelong, Geelong, Australia
| | - Justin J Kavanagh
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
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15
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Kavanagh JJ, Taylor JL. Voluntary activation of muscle in humans: does serotonergic neuromodulation matter? J Physiol 2022; 600:3657-3670. [PMID: 35864781 PMCID: PMC9541597 DOI: 10.1113/jp282565] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 07/12/2022] [Indexed: 11/08/2022] Open
Abstract
Ionotropic inputs to motoneurones have the capacity to depolarise and hyperpolarise the motoneurone, whereas neuromodulatory inputs control the state of excitability of the motoneurone. Intracellular recordings of motoneurones from in vitro and in situ animal preparations have provided extraordinary insight into the mechanisms that underpin how neuromodulators regulate neuronal excitability. However, far fewer studies have attempted to translate the findings from cellular and molecular studies into a human model. In this review, we focus on the role that serotonin (5-HT) plays in muscle activation in humans. 5-HT is a potent regulator of neuronal firing rates, which can influence the force that can be generated by muscles during voluntary contractions. We firstly outline structural and functional characteristics of the serotonergic system, and then describe how motoneurone discharge can be facilitated and suppressed depending on the 5-HT receptor subtype that is activated. We then provide a narrative on how 5-HT effects can influence voluntary activation during muscle contractions in humans, and detail how 5-HT may be a mediator of exercise-induced fatigue that arises from the central nervous system.
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Affiliation(s)
- Justin J. Kavanagh
- Neural Control of Movement laboratoryMenzies Health Institute QueenslandGriffith UniversityGold CoastAustralia
| | - Janet L. Taylor
- Centre for Human Performance, School of Medical and Health SciencesEdith Cowan UniversityPerthAustralia
- Neuroscience Research AustraliaSydneyAustralia
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16
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Thorstensen JR, Taylor JL, Kavanagh JJ. 5-HT 2 receptor antagonism reduces human motoneuron output to antidromic activation but not to stimulation of corticospinal axons. Eur J Neurosci 2022; 56:3674-3686. [PMID: 35445439 PMCID: PMC9543143 DOI: 10.1111/ejn.15672] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 03/19/2022] [Accepted: 04/07/2022] [Indexed: 12/01/2022]
Abstract
The intrinsic electrical properties of motoneurons strongly affect motoneuron excitability to fast-acting excitatory ionotropic inputs. Serotonin (5-HT) is a neurochemical that alters the intrinsic properties of motoneurons, whereby animal models and in vitro experiments indicate that 5-HT increases motoneuron excitability by activating 5-HT2 receptors on the somato-dendritic compartment. In the current study, we examined how antagonism of the 5-HT2 receptor affects motoneuron excitability in humans. We hypothesised that motoneuron excitability would be reduced. The 5-HT2 antagonist cyproheptadine was administered to ten healthy participants in a double-blinded, placebo-controlled, crossover trial. Electrical cervicomedullary stimulation was used to deliver a synchronised excitatory volley to motoneurons to elicit cervicomedullary motor evoked potentials (CMEPs) in the surface electromyography (EMG) signal of the resting biceps brachii. Likewise, electrical peripheral nerve stimulation was used to generate antidromic spikes in motoneurons and cause recurrent discharges, which were recorded with surface EMG as F-waves in a resting hand muscle. Compared to placebo, we found that 5-HT2 antagonism reduced the amplitude and persistence of F-waves but did not affect CMEP amplitude. 5-HT2 antagonism also reduced maximal contraction strength. The reduced recurrent discharge of motoneurons with 5-HT2 antagonism suggests that 5-HT2 receptors modulate the electrical properties of the initial segment or soma to promote excitability. Conversely, as cyproheptadine did not affect motoneuron excitability to brief synaptic input, but affected maximal contractions requiring sustained input, it seems likely that the 5-HT2 mediated amplification of synaptic input at motoneuron dendrites is functionally significant only when excitatory input activates persistent inward currents.
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Affiliation(s)
- Jacob R Thorstensen
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Janet L Taylor
- School of Medical and Health Sciences, Edith Cowan University, Perth, Australia.,Neuroscience Research Australia, Sydney, Australia
| | - Justin J Kavanagh
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
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17
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Central and Peripheral Fatigue in Physical Exercise Explained: A Narrative Review. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19073909. [PMID: 35409591 PMCID: PMC8997532 DOI: 10.3390/ijerph19073909] [Citation(s) in RCA: 46] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 03/16/2022] [Accepted: 03/21/2022] [Indexed: 02/07/2023]
Abstract
The study of the origin and implications of fatigue in exercise has been widely investigated, but not completely understood given the complex multifactorial mechanisms involved. Then, it is essential to understand the fatigue mechanism to help trainers and physicians to prescribe an adequate training load. The present narrative review aims to analyze the multifactorial factors of fatigue in physical exercise. To reach this aim, a consensus and critical review were performed using both primary sources, such as scientific articles, and secondary ones, such as bibliographic indexes, web pages, and databases. The main search engines were PubMed, SciELO, and Google Scholar. Central and peripheral fatigue are two unison constructs part of the Integrative Governor theory, in which both psychological and physiological drives and requirements are underpinned by homeostatic principles. The relative activity of each one is regulated by dynamic negative feedback activity, as the fundamental general operational controller. Fatigue is conditioned by factors such as gender, affecting men and women differently. Sleep deprivation or psychological disturbances caused, for example, by stress, can affect neural activation patterns, realigning them and slowing down simple mental operations in the context of fatigue. Then, fatigue can have different origins not only related with physiological factors. Therefore, all these prisms must be considered for future approaches from sport and clinical perspectives.
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18
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Zhu H, Wang R, Hua H, Cheng Y, Guo Y, Qian H, Du P. The macamide relieves fatigue by acting as inhibitor of inflammatory response in exercising mice: From central to peripheral. Eur J Pharmacol 2022; 917:174758. [PMID: 35026191 DOI: 10.1016/j.ejphar.2022.174758] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 01/07/2022] [Accepted: 01/07/2022] [Indexed: 12/31/2022]
Abstract
Macamides are the major and unique bioactive compounds of Lepidium meyenii (Walp.) or Maca. N-benzyl-(9Z, 12Z)-octadecadienamide (N-benzyl-linoleamide) is one of the most biologically active macamides with various pharmacological activities - anti-fatigue, neuroprotective, antioxidant, anti-tumoral activities, anti-inflammatory, and analgesic. In this study, the anti-fatigue properties of N-benzyl-(9Z, 12Z)-octadecadienamide were further evaluated by a weight-loaded forced swimming test. Results indicated N-benzyl-(9Z, 12Z)-octadecadienamide supplementation increased the forelimb grip strength of mice and exercising time remaining on the Rota-rod test. Furthermore, significant decreases in pro-inflammatory factors and reactive oxygen species (ROS) contents were observed in mice receiving N-benzyl-(9Z, 12Z)-octadecadienamide treatment after a 30 min swimming test, which was equivalent to that of caffeine. Histological analysis also indicated that N-benzyl-(9Z, 12Z)-octadecadienamide attenuated damage to the liver in mice by up-regulating the expression of heme oxygenase-1 (HO-1) and inhibiting the expression of Interleukin (IL)-1β during exercise. Pearson correlation analysis suggested peripheral fatigue indexes, including energy sources, metabolites were significantly correlated with inflammatory factors and ROS levels. Likewise, central fatigue parameters are also associated, including hippocampal inflammatory response and hypothalamic neurotransmitters. Hence, macamides can be considered to have great potential as a natural drug with high efficiency and low side effects for fatigue management.
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Affiliation(s)
- Hongkang Zhu
- School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
| | - Ruoyong Wang
- Air Force Medical Center, Beijing, 100142, China
| | - Hanyi Hua
- School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
| | - Yuliang Cheng
- School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
| | - Yahui Guo
- School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
| | - He Qian
- School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.
| | - Peng Du
- Air Force Medical Center, Beijing, 100142, China.
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19
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Hirschbeck A, Leao DS, Wagner E, Hasan A, Roeh A. Psychiatric medication and physical performance parameters - Are there implications for treatment? Front Psychiatry 2022; 13:985983. [PMID: 36147967 PMCID: PMC9488519 DOI: 10.3389/fpsyt.2022.985983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 08/16/2022] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION The impact of psychiatric medications and their enhancing or impairing effects on physical performance remains inconclusive. Therefore, with this systematic review we provide a comprehensive overview of frequently used psychotropic drugs and their effects on physical performance for the purpose of providing empirical information and deriving prescription and therapy recommendations for clinical practice. METHODS We systematically searched PubMed, PsycInfo, and Cochrane databases and extracted human studies investigating the effect of psychotropic drugs on parameters associated with the level of physical performance, such as exercise time, oxygen consumption, heart rate, muscle contraction or blood lactate concentration in physically healthy participants. 36 studies - comprising a broad range of psychotropic agents, such as antidepressants, antipsychotics, sedatives, and stimulants - were selected for final analyses. RESULTS Most studies (N = 32) were randomized controlled trials (RCT) with a double-blind crossover design. Antidepressants (N = 21) were the most frequently studied drug class, with contradictory results e.g., performance enhancement in warm environment but not in temperate conditions for bupropion or inconsistent findings between studies for other antidepressants. Antipsychotics (N = 3) mainly showed impairing effects on physical performance, while stimulants (N = 4) were often performance-enhancing. Sedatives (N = 9) may cause a hangover effect. CONCLUSION The examined studies with heterogeneous design showed different effects of psychiatric medications on physical performance. Antipsychotics seemed to be performance impairing, while the findings for antidepressants and sedatives were more inconsistent. Stimulants were the only group with consistent performance-enhancing effects. However, most studies were conducted with a small sample size (N < 10), mostly in well-trained subjects rather than in patients with psychiatric disorders, and most studies used single-dose designs. These issues impede the formulation of generalized conclusions for treatment regimes and should therefore be considered in further longitudinal studies for clinically reliable statements. Nevertheless, answering our research question is quite relevant for clinical practice and therapeutic prescription and should be further investigated especially considering the high drop-out rates in drug treatment. SYSTEMATIC REVIEW REGISTRATION [https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=276103], identifier [CRD42021276103].
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Affiliation(s)
- Anna Hirschbeck
- Department of Psychiatry, Psychotherapy and Psychosomatics, Bezirkskrankenhaus Augsburg, Medical Faculty, University of Augsburg, Augsburg, Germany
| | - Douglas Silva Leao
- Department of Psychiatry, Psychotherapy and Psychosomatics, Bezirkskrankenhaus Augsburg, Medical Faculty, University of Augsburg, Augsburg, Germany
| | - Elias Wagner
- Department of Psychiatry and Psychotherapy, University Hospital, Ludwig Maximilian University of Munich, Munich, Germany
| | - Alkomiet Hasan
- Department of Psychiatry, Psychotherapy and Psychosomatics, Bezirkskrankenhaus Augsburg, Medical Faculty, University of Augsburg, Augsburg, Germany
| | - Astrid Roeh
- Department of Psychiatry, Psychotherapy and Psychosomatics, Bezirkskrankenhaus Augsburg, Medical Faculty, University of Augsburg, Augsburg, Germany
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20
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Henderson TT, Thorstensen JR, Morrison S, Tucker MG, Kavanagh JJ. Physiological tremor is suppressed and force steadiness is enhanced with increased availability of serotonin regardless of muscle fatigue. J Neurophysiol 2022; 127:27-37. [PMID: 34851768 DOI: 10.1152/jn.00403.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Although there is evidence that 5-HT acts as an excitatory neuromodulator to enhance maximal force generation, it is largely unknown how 5-HT activity influences the ability to sustain a constant force during steady-state contractions. A total of 22 healthy individuals participated in the study, where elbow flexion force was assessed during brief isometric contractions at 10% maximal voluntary contraction (MVC), 60% MVC, MVC, and during a sustained MVC. The selective serotonin reuptake inhibitor, paroxetine, suppressed physiological tremor and increased force steadiness when performing the isometric contractions. In particular, a main effect of drug was detected for peak power of force within the 8-12 Hz range (P = 0.004) and the coefficient of variation (CV) of force (P < 0.001). A second experiment was performed where intermittent isometric elbow flexions (20% MVC sustained for 2 min) were repeatedly performed so that serotonergic effects on physiological tremor and force steadiness could be assessed during the development of fatigue. Main effects of drug were once again detected for peak power of force in the 8-12 Hz range (P = 0.002) and CV of force (P = 0.003), where paroxetine suppressed physiological tremor and increased force steadiness when the elbow flexors were fatigued. The findings of this study suggest that enhanced availability of 5-HT in humans has a profound influence of maintaining constant force during steady-state contractions. The action of 5-HT appears to suppress fluctuations in force regardless of the fatigue state of the muscle.NEW & NOTEWORTHY Converging lines of research indicate that enhanced serotonin availability increases maximal force generation. However, it is largely unknown how serotonin influences the ability to sustain a constant force. We performed two experiments to assess physiological tremor and force steadiness in unfatigued and fatigued muscle when serotonin availability was enhanced in the central nervous system. Enhanced availability of serotonin reduced physiological tremor amplitude and improved steadiness regardless of muscle fatigue.
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Affiliation(s)
- T T Henderson
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
| | - J R Thorstensen
- Child Health Research Centre, The University of Queensland, Brisbane, Queensland, Australia
| | - S Morrison
- School of Rehabilitation Sciences, Old Dominion University, Norfolk, Virginia
| | - M G Tucker
- Barwon Health, University Hospital Geelong, Melbourne, Victoria, Australia
| | - J J Kavanagh
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
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21
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Marcon M, Zanella P. The effect of branched-chain amino acids supplementation in physical exercise: A systematic review of human randomized controlled trials. Sci Sports 2022. [DOI: 10.1016/j.scispo.2021.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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22
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Goodlich BI, Horan SA, Kavanagh JJ. Blockade of 5-HT 2 receptors suppresses rate of torque development and motor unit discharge rate during rapid contractions. J Neurophysiol 2021; 127:150-160. [PMID: 34936830 DOI: 10.1152/jn.00470.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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 prior to 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), where 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.
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Affiliation(s)
| | - Sean A Horan
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Justin J Kavanagh
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
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23
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Bai T, Wu F, Yan S, Zhang F, Xu X. Construction and Evaluation of a Rat Model of Postpartum Fatigue. Gynecol Obstet Invest 2021; 86:370-378. [PMID: 34455407 DOI: 10.1159/000517997] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 06/18/2021] [Indexed: 11/19/2022]
Abstract
OBJECTIVES The aim of the study was to construct and evaluate a rat model of postpartum fatigue. DESIGN This is an article about animal model building. METHODS Sprague-Dawley rats on the 1st day after delivery were randomized into control group and fatigue group. The deep sleep of rats was interfered with by forcing them to stand in water, to make the rats experience mental and physical fatigue. To maintain galactosis and lactation, rats and pups were caged for 90 min after every 3 h of separation. The control group was separated routinely without any stimulus. The model was evaluated from mental and physical fatigue on the 8th day and 15th day. The mental fatigue was evaluated by a water maze test and the rat's 5-hydroxytryptamine (5-HT) level in hippocampus, while the physical fatigue was evaluated using lactic acid level in serum and duration of weight-loaded forced swimming. RESULTS Among the 7-day and 14-day modeling groups, compared with the control group, the success rate of water maze landing was significantly decreased, the time for water maze landing was significantly prolonged and 5-HT level in hippocampus significantly decreased in the fatigue group. With respect to physical fatigue, among the 7-day and 14-day modeling groups, the lactic acid level in serum in the fatigue group was significantly increased, and the duration of exhaustive swimming of rats was significantly shortened. LIMITATIONS A small sample size was the main limitation of this study. CONCLUSIONS We have successfully constructed a rat model of postpartum fatigue by forcing postpartum rats to stand in water, which was similar to a level of stress that contributes to the development of postpartum fatigue. Our model opens the door for future studies evaluating the effectiveness of pharmacological and behavioral therapies.
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Affiliation(s)
- Ting Bai
- Medical College of Nantong University, Nantong, China
| | - Fan Wu
- Medical College of Nantong University, Nantong, China
| | - Shuhan Yan
- Medical College of Nantong University, Nantong, China
| | - Feng Zhang
- Medical College of Nantong University, Nantong, China
| | - Xujuan Xu
- Nursing Research Institute of Affiliated Hospital of Nantong University, Nantong, China
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24
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Zeugin D, Ionta S. Anatomo-Functional Origins of the Cortical Silent Period: Spotlight on the Basal Ganglia. Brain Sci 2021; 11:705. [PMID: 34071742 PMCID: PMC8227635 DOI: 10.3390/brainsci11060705] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/17/2021] [Accepted: 05/25/2021] [Indexed: 02/06/2023] Open
Abstract
The so-called cortical silent period (CSP) refers to the temporary interruption of electromyographic signal from a muscle following a motor-evoked potential (MEP) triggered by transcranial magnetic stimulation (TMS) over the primary motor cortex (M1). The neurophysiological origins of the CSP are debated. Previous evidence suggests that both spinal and cortical mechanisms may account for the duration of the CSP. However, contextual factors such as cortical fatigue, experimental procedures, attentional load, as well as neuropathology can also influence the CSP duration. The present paper summarizes the most relevant evidence on the mechanisms underlying the duration of the CSP, with a particular focus on the central role of the basal ganglia in the "direct" (excitatory), "indirect" (inhibitory), and "hyperdirect" cortico-subcortical pathways to manage cortical motor inhibition. We propose new methods of interpretation of the CSP related, at least partially, to the inhibitory hyperdirect and indirect pathways in the basal ganglia. This view may help to explain the respective shortening and lengthening of the CSP in various neurological disorders. Shedding light on the complexity of the CSP's origins, the present review aims at constituting a reference for future work in fundamental research, technological development, and clinical settings.
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Affiliation(s)
| | - Silvio Ionta
- Sensory-Motor Laboratory (SeMoLa), Jules-Gonin Eye Hospital/Fondation Asile des Aveugles, Department of Ophthalmology, University of Lausanne, 1002 Lausanne, Switzerland
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25
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Brownstein CG, Espeit L, Royer N, Ansdell P, Škarabot J, Souron R, Lapole T, Millet GY. Reductions in motoneuron excitability during sustained isometric contractions are dependent on stimulus and contraction intensity. J Neurophysiol 2021; 125:1636-1646. [PMID: 33788627 DOI: 10.1152/jn.00070.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cervicomedullary stimulation provides a means of assessing motoneuron excitability. Previous studies demonstrated that during low-intensity sustained contractions, small cervicomedullary evoked potentials (CMEPs) conditioned using transcranial magnetic stimulation (TMS-CMEPs) are reduced, whereas large TMS-CMEPs are less affected. As small TMS-CMEPs recruit motoneurons most active during low-intensity contractions whereas large TMS-CMEPs recruit a high proportion of motoneurons inactive during the task, these results suggest that reductions in motoneuron excitability could be dependent on repetitive activation. To further test this hypothesis, this study assessed changes in small and large TMS-CMEPs across low- and high-intensity contractions. Twelve participants performed a sustained isometric contraction of the elbow flexor for 4.5 min at the electromyography (EMG) level associated with 20% maximal voluntary contraction force (MVC; low intensity) and 70% MVC (high intensity). Small and large TMS-CMEPs with amplitudes of ∼15% and ∼50% Mmax at baseline, respectively, were delivered every minute throughout the tasks. Recovery measures were taken at 1-, 2.5- and 4-min postexercise. During the low-intensity trial, small TMS-CMEPs were reduced at 2-4 min (P ≤ 0.049) by up to -10% Mmax, whereas large TMS-CMEPs remained unchanged (P ≥ 0.16). During the high-intensity trial, small and large TMS-CMEPs were reduced at all time points (P < 0.01) by up to -14% and -33% Mmax, respectively, and remained below baseline during all recovery measures (P ≤ 0.02). TMS-CMEPs were unchanged relative to baseline during recovery following the low-intensity trial (P ≥ 0.24). These results provide novel insight into motoneuron excitability during and following sustained contractions at different intensities and suggest that contraction-induced reductions in motoneuron excitability depend on repetitive activation.NEW & NOTEWORTHY This study measured motoneuron excitability using cervicomedullary evoked potentials conditioned using transcranial magnetic stimulation (TMS-CMEPs) of both small and large amplitudes during sustained low- and high-intensity contractions of the elbow flexors. During the low-intensity task, only the small TMS-CMEP was reduced. During the high-intensity task, both small and large TMS-CMEPs were substantially reduced. These results indicate that repetitively active motoneurons are specifically reduced in excitability compared with less active motoneurons in the same pool.
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Affiliation(s)
- Callum G Brownstein
- Inter-university Laboratory of Human Movement Science, University Lyon, Université Jean Monnet (UJM)-Saint-Etienne, Saint-Etienne, France
| | - Loïc Espeit
- Inter-university Laboratory of Human Movement Science, University Lyon, Université Jean Monnet (UJM)-Saint-Etienne, Saint-Etienne, France
| | - Nicolas Royer
- Inter-university Laboratory of Human Movement Science, University Lyon, Université Jean Monnet (UJM)-Saint-Etienne, Saint-Etienne, France
| | - Paul Ansdell
- Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Jakob Škarabot
- School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, United Kingdom
| | - Robin Souron
- Laboratory of Impact of Physical Activity on Health (IAPS), University of Toulon, France
| | - Thomas Lapole
- Inter-university Laboratory of Human Movement Science, University Lyon, Université Jean Monnet (UJM)-Saint-Etienne, Saint-Etienne, France
| | - Guillaume Y Millet
- Inter-university Laboratory of Human Movement Science, University Lyon, Université Jean Monnet (UJM)-Saint-Etienne, Saint-Etienne, France.,Institut Universitaire de France (IUF)
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26
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Thorstensen JR, Taylor JL, Kavanagh JJ. Human corticospinal-motoneuronal output is reduced with 5-HT 2 receptor antagonism. J Neurophysiol 2021; 125:1279-1288. [PMID: 33596722 DOI: 10.1152/jn.00698.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Animal models indicate that serotonin (5-HT) release onto motoneurons facilitates motor output, particularly during strong motor activities. However, evidence for 5-HT effects during human movement are limited. This study examined how antagonism of the 5-HT2 receptor, which is a 5-HT receptor that promotes motoneuron excitability, affects human movement. Ten healthy participants (24.2 ± 1.9 yr) ingested 8 mg of cyproheptadine (competitive 5-HT2 antagonist) in a double-blinded, placebo-controlled, repeated-measures design. Transcranial magnetic stimulation (TMS) of the motor cortex was used to elicit motor evoked potentials (MEPs) from biceps brachii. First, stimulus-response curves (90%-160% active motor threshold) were obtained during very weak elbow flexions (10% of maximal). Second, to determine if 5-HT effects are scaled to the intensity of muscle contraction, TMS at a fixed intensity was applied during elbow flexions of 20%, 40%, 60%, 80%, and 100% of maximal. Cyproheptadine reduced the size of MEPs across the stimulus-response curves (P = 0.045). Notably, MEP amplitude was 22.3% smaller for the cyproheptadine condition for the strongest TMS intensity. In addition, cyproheptadine reduced maximal torque (P = 0.045), lengthened the biceps silent period during maximal elbow flexions (P = 0.037), and reduced superimposed twitch amplitude during moderate-intensity elbow flexions (P = 0.035). This study presents novel evidence that 5-HT2 receptors influence corticospinal-motoneuronal output, which was particularly evident when a large number of descending inputs to motoneurons were active. Although it is likely that antagonism of 5-HT2 receptors reduces motoneuron gain to ionotropic inputs, supraspinal mechanisms may have also contributed to the study findings.NEW & NOTEWORTHY Voluntary contractions and responses to magnetic stimulation of the motor cortex are dependent on serotonin activity in the central nervous system. 5-HT2 antagonism decreased evoked potential size to high-intensity stimulation, and reduced torque and lengthened inhibitory silent periods during maximal contractions. We provide novel evidence that 5-HT2 receptors are involved in muscle activation, where 5-HT effects are strongest when a large number of descending inputs activate motoneurons.
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Affiliation(s)
- Jacob R Thorstensen
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
| | - Janet L Taylor
- School of Medical and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia.,Neuroscience Research Australia (NeuRA), Sydney, New South Wales, Australia
| | - Justin J Kavanagh
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
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27
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Ortelli P, Ferrazzoli D, Sebastianelli L, Engl M, Romanello R, Nardone R, Bonini I, Koch G, Saltuari L, Quartarone A, Oliviero A, Kofler M, Versace V. Neuropsychological and neurophysiological correlates of fatigue in post-acute patients with neurological manifestations of COVID-19: Insights into a challenging symptom. J Neurol Sci 2020; 420:117271. [PMID: 33359928 PMCID: PMC7834526 DOI: 10.1016/j.jns.2020.117271] [Citation(s) in RCA: 148] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/09/2020] [Accepted: 12/11/2020] [Indexed: 01/08/2023]
Abstract
More than half of patients who recover from COVID-19 experience fatigue. We studied fatigue using neuropsychological and neurophysiological investigations in post-COVID-19 patients and healthy subjects. Neuropsychological assessment included: Fatigue Severity Scale (FSS), Fatigue Rating Scale, Beck Depression Inventory, Apathy Evaluation Scale, cognitive tests, and computerized tasks. Neurophysiological examination was assessed before (PRE) and 2 min after (POST) a 1-min fatiguing isometric pinching task and included: maximum compound muscle action potential (CMAP) amplitude in first dorsal interosseous muscle (FDI) following ulnar nerve stimulation, resting motor threshold, motor evoked potential (MEP) amplitude and silent period (SP) duration in right FDI following transcranial magnetic stimulation of the left motor cortex. Maximum pinch strength was measured. Perceived exertion was assessed with the Borg-Category-Ratio scale. Patients manifested fatigue, apathy, executive deficits, impaired cognitive control, and reduction in global cognition. Perceived exertion was higher in patients. CMAP and MEP were smaller in patients both PRE and POST. CMAP did not change in either group from PRE to POST, while MEP amplitudes declined in controls POST. SP duration did not differ between groups PRE, increased in controls but decreased in patients POST. Patients' change of SP duration from PRE to POST was negatively correlated to FSS. Abnormal SP shortening and lack of MEP depression concur with a reduction in post-exhaustion corticomotor inhibition, suggesting a possible GABAB-ergic dysfunction. This impairment might be related to the neuropsychological alterations. COVID-19-associated inflammation might lead to GABAergic impairment, possibly representing the basis of fatigue and explaining apathy and executive deficits.
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Affiliation(s)
- Paola Ortelli
- Department of Neurorehabilitation, Hospital of Vipiteno (SABES-ASDAA), Vipiteno-Sterzing, Italy.
| | - Davide Ferrazzoli
- Department of Neurorehabilitation, Hospital of Vipiteno (SABES-ASDAA), Vipiteno-Sterzing, Italy
| | - Luca Sebastianelli
- Department of Neurorehabilitation, Hospital of Vipiteno (SABES-ASDAA), Vipiteno-Sterzing, Italy
| | - Michael Engl
- Medical Director, Hospital of Vipiteno (SABES-ASDAA), Vipiteno-Sterzing, Italy
| | - Roberto Romanello
- Department of Neurorehabilitation, Hospital of Vipiteno (SABES-ASDAA), Vipiteno-Sterzing, Italy
| | - Raffaele Nardone
- Department of Neurology, Franz Tappeiner Hospital (SABES-ASDAA), Merano-Meran, Italy; Department of Neurology, Christian Doppler Medical Center, Paracelsus University Salzburg, Austria
| | - Ilenia Bonini
- Department of Neurorehabilitation, Hospital of Vipiteno (SABES-ASDAA), Vipiteno-Sterzing, Italy
| | - Giacomo Koch
- Non-Invasive Brain Stimulation Unit/Department of Behavioral and Clinical Neurology, Santa Lucia Foundation IRCCS, Rome, Italy
| | - Leopold Saltuari
- Department of Neurorehabilitation, Hospital of Vipiteno (SABES-ASDAA), Vipiteno-Sterzing, Italy
| | - Angelo Quartarone
- Department of Biomedical Science and Morphological and Functional Images, University of Messina, Italy; IRCCS Centro "Bonino Pulejo", Messina, Italy
| | - Antonio Oliviero
- FENNSI Group, Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla La Mancha, Toledo, Spain
| | - Markus Kofler
- Department of Neurology, Hochzirl Hospital, Zirl, Austria
| | - Viviana Versace
- Department of Neurorehabilitation, Hospital of Vipiteno (SABES-ASDAA), Vipiteno-Sterzing, Italy
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28
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Martinez-Valdes E, Negro F, Falla D, Dideriksen JL, Heckman CJ, Farina D. Inability to increase the neural drive to muscle is associated with task failure during submaximal contractions. J Neurophysiol 2020; 124:1110-1121. [DOI: 10.1152/jn.00447.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Motor unit firing and contractile properties during a submaximal contraction until failure were assessed with a new tracking technique. Two distinct phases in firing behavior were observed, which compensated for changes in twitch area and predicted time to failure. However, the late increase in firing rate was below the rates attained in the absence of fatigue, which points to an inability of the central nervous system to sufficiently increase the neural drive to muscle with fatigue.
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Affiliation(s)
- Eduardo Martinez-Valdes
- Centre of Precision Rehabilitation for Spinal Pain (CPR Spine), School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Francesco Negro
- Department of Clinical and Experimental Sciences, Research Centre for Neuromuscular Function and Adapted Physical Activity “Teresa Camplani,” Università degli Studi di Brescia, Brescia, Italy
| | - Deborah Falla
- Centre of Precision Rehabilitation for Spinal Pain (CPR Spine), School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Jakob Lund Dideriksen
- Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - C. J. Heckman
- Department of Physiology, Northwestern University, Chicago, Illinois
| | - Dario Farina
- Department of Bioengineering, Imperial College London, Royal School of Mines, London, United Kingdom
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29
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Brownstein CG, Espeit L, Royer N, Lapole T, Millet GY. Fatigue-induced changes in short-interval intracortical inhibition and the silent period with stimulus intensities evoking maximal versus submaximal responses. J Appl Physiol (1985) 2020; 129:205-217. [PMID: 32584668 DOI: 10.1152/japplphysiol.00282.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
During fatiguing exercise, previous studies have employed transcranial magnetic stimulation (TMS) paradigms eliciting either maximal or submaximal short-interval intracortical inhibition (SICI) and silent period (SP) durations. However, the effect of using either approach on the change in these variables with fatigue is unknown. This study examined the effects of using conditioning stimulus (CS, experiment A) and single-pulse TMS intensities (experiment B) that elicit maximal and submaximal SICI and SP duration (MaxSICI vs. SubmaxSICI in experiment A, MaxSP vs. SubmaxSP in experiment B) on the change in these measures with fatigue. In both experiments, participants performed a 10-min sustained isometric knee-extension contraction at a constant level of EMG, with measurements taken with maximal and submaximal intensities at baseline and every 2.5 min throughout the task. Immediately after the 10-min contraction (i.e., without recovery), responses were also measured at the same absolute force level as at baseline. In experiment A, no change in SICI was observed with either CS intensity throughout the EMG task (P > 0.05). However, an 18% decrease in SICI (i.e., less inhibition) was observed at the same absolute force only with the MaxSICI CS intensity (P < 0.01), with no change in SubmaxSICI (P = 0.72). In experiment B, the magnitude of increase in SP with fatigue was similar for both stimulus intensities (stimulus × time interaction: P = 0.44). These results suggest that CS intensities eliciting maximum SICI are more sensitive in detecting fatigue-induced reductions in SICI, whereas increases in SP are detectable with TMS intensities evoking maximal or submaximal SPs.NEW & NOTEWORTHY This study compared the change in silent period (SP) and short-interval intracortical inhibition (SICI) with conditioning stimulus and single-pulse transcranial magnetic stimulation (TMS) intensities (for SICI and SP, respectively) eliciting maximal and submaximal SICI and SP during fatiguing exercise. The results showed that changes in SICI were only detectable with intensities evoking maximal responses, with no difference between intensities for SP. These findings highlight the importance of maximizing SICI with appropriate intensities before measuring SICI during fatiguing exercise.
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Affiliation(s)
- Callum G Brownstein
- Inter-University Laboratory of Human Movement Science, Université Claude Bernard Lyon 1 and Université Jean Monnet-Saint-Etienne, EA 7424, Saint-Etienne, France
| | - Loïc Espeit
- Inter-University Laboratory of Human Movement Science, Université Claude Bernard Lyon 1 and Université Jean Monnet-Saint-Etienne, EA 7424, Saint-Etienne, France
| | - Nicolas Royer
- Inter-University Laboratory of Human Movement Science, Université Claude Bernard Lyon 1 and Université Jean Monnet-Saint-Etienne, EA 7424, Saint-Etienne, France
| | - Thomas Lapole
- Inter-University Laboratory of Human Movement Science, Université Claude Bernard Lyon 1 and Université Jean Monnet-Saint-Etienne, EA 7424, Saint-Etienne, France
| | - Guillaume Y Millet
- Inter-University Laboratory of Human Movement Science, Université Claude Bernard Lyon 1 and Université Jean Monnet-Saint-Etienne, EA 7424, Saint-Etienne, France
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30
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Pearcey GEP, Heckman CJ. Serotonin affects our perception of fatigue when performing submaximal efforts - but is it all in our heads? J Physiol 2020; 598:2533-2534. [PMID: 32390162 DOI: 10.1113/jp279883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Gregory E P Pearcey
- Physiology, Physical Medicine and Rehabilitation, Physical Therapy and Human Movement Sciences, Shirley Ryan AbilityLab, Northwestern University, Chicago, IL, USA
| | - C J Heckman
- Physiology, Physical Medicine and Rehabilitation, Physical Therapy and Human Movement Sciences, Shirley Ryan AbilityLab, Northwestern University, Chicago, IL, USA
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