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Ó Murchú SC, O'Halloran KD. BREATHE DMD: boosting respiratory efficacy after therapeutic hypoxic episodes in Duchenne muscular dystrophy. J Physiol 2024. [PMID: 38837229 DOI: 10.1113/jp280280] [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: 03/08/2024] [Accepted: 05/12/2024] [Indexed: 06/07/2024] Open
Abstract
Duchenne muscular dystrophy (DMD) is a fatal genetic neuromuscular disorder, characterised by progressive decline in skeletal muscle function due to the secondary consequences of dystrophin deficiency. Weakness extends to the respiratory musculature, and cardiorespiratory failure is the leading cause of death in men with DMD. Intermittent hypoxia has emerged as a potential therapy to counteract ventilatory insufficiency by eliciting long-term facilitation of breathing. Mechanisms of sensory and motor facilitation of breathing have been well delineated in animal models. Various paradigms of intermittent hypoxia have been designed and implemented in human trials culminating in clinical trials in people with spinal cord injury and amyotrophic lateral sclerosis. Application of therapeutic intermittent hypoxia to DMD is considered together with discussion of the potential barriers to progression owing to the complexity of this devastating disease. Notwithstanding the considerable challenges and potential pitfalls of intermittent hypoxia-based therapies for DMD, we suggest it is incumbent on the research community to explore the potential benefits in pre-clinical models. Intermittent hypoxia paradigms should be implemented to explore the proclivity to express respiratory plasticity with the longer-term aim of preserving and potentiating ventilation in pre-clinical models and people with DMD.
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Affiliation(s)
- Seán C Ó Murchú
- Department of Physiology, University College Cork, Cork, Ireland
| | - Ken D O'Halloran
- Department of Physiology, University College Cork, Cork, Ireland
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2
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Marciante AB, Tadjalli A, Burrowes KA, Oberto JR, Luca EK, Seven YB, Nikodemova M, Watters JJ, Baker TL, Mitchell GS. Microglia regulate motor neuron plasticity via reciprocal fractalkine/adenosine signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.07.592939. [PMID: 38765982 PMCID: PMC11100694 DOI: 10.1101/2024.05.07.592939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Microglia are innate CNS immune cells that play key roles in supporting key CNS functions including brain plasticity. We now report a previously unknown role for microglia in regulating neuroplasticity within spinal phrenic motor neurons, the neurons driving diaphragm contractions and breathing. We demonstrate that microglia regulate phrenic long-term facilitation (pLTF), a form of respiratory memory lasting hours after repetitive exposures to brief periods of low oxygen (acute intermittent hypoxia; AIH) via neuronal/microglial fractalkine signaling. AIH-induced pLTF is regulated by the balance between competing intracellular signaling cascades initiated by serotonin vs adenosine, respectively. Although brainstem raphe neurons release the relevant serotonin, the cellular source of adenosine is unknown. We tested a model in which hypoxia initiates fractalkine signaling between phrenic motor neurons and nearby microglia that triggers extracellular adenosine accumulation. With moderate AIH, phrenic motor neuron adenosine 2A receptor activation undermines serotonin-dominant pLTF; in contrast, severe AIH drives pLTF by a unique, adenosine-dominant mechanism. Phrenic motor neuron fractalkine knockdown, cervical spinal fractalkine receptor inhibition on nearby microglia, and microglial depletion enhance serotonin-dominant pLTF with moderate AIH but suppress adenosine-dominant pLTF with severe AIH. Thus, microglia play novel functions in the healthy spinal cord, regulating hypoxia-induced neuroplasticity within the motor neurons responsible for breathing.
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Affiliation(s)
- Alexandria B. Marciante
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida; Gainesville, FL, USA 32610
| | - Arash Tadjalli
- Current Address: Nova Southeastern University, College of Allopathic Medicine (NSU MD), Department of Medical Education, 3200 South University Drive, Fort Lauderdale, FL 33328-2018
| | - Kayla A. Burrowes
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida; Gainesville, FL, USA 32610
| | - Jose R. Oberto
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida; Gainesville, FL, USA 32610
| | - Edward K. Luca
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida; Gainesville, FL, USA 32610
| | - Yasin B. Seven
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida; Gainesville, FL, USA 32610
| | - Maria Nikodemova
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida; Gainesville, FL, USA 32610
| | - Jyoti J. Watters
- Current Address: Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Drive, Madison, WI 53706
| | - Tracy L. Baker
- Current Address: Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Drive, Madison, WI 53706
| | - Gordon S. Mitchell
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida; Gainesville, FL, USA 32610
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3
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Burtscher J, Citherlet T, Camacho-Cardenosa A, Camacho-Cardenosa M, Raberin A, Krumm B, Hohenauer E, Egg M, Lichtblau M, Müller J, Rybnikova EA, Gatterer H, Debevec T, Baillieul S, Manferdelli G, Behrendt T, Schega L, Ehrenreich H, Millet GP, Gassmann M, Schwarzer C, Glazachev O, Girard O, Lalande S, Hamlin M, Samaja M, Hüfner K, Burtscher M, Panza G, Mallet RT. Mechanisms underlying the health benefits of intermittent hypoxia conditioning. J Physiol 2023. [PMID: 37860950 DOI: 10.1113/jp285230] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Accepted: 10/11/2023] [Indexed: 10/21/2023] Open
Abstract
Intermittent hypoxia (IH) is commonly associated with pathological conditions, particularly obstructive sleep apnoea. However, IH is also increasingly used to enhance health and performance and is emerging as a potent non-pharmacological intervention against numerous diseases. Whether IH is detrimental or beneficial for health is largely determined by the intensity, duration, number and frequency of the hypoxic exposures and by the specific responses they engender. Adaptive responses to hypoxia protect from future hypoxic or ischaemic insults, improve cellular resilience and functions, and boost mental and physical performance. The cellular and systemic mechanisms producing these benefits are highly complex, and the failure of different components can shift long-term adaptation to maladaptation and the development of pathologies. Rather than discussing in detail the well-characterized individual responses and adaptations to IH, we here aim to summarize and integrate hypoxia-activated mechanisms into a holistic picture of the body's adaptive responses to hypoxia and specifically IH, and demonstrate how these mechanisms might be mobilized for their health benefits while minimizing the risks of hypoxia exposure.
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Affiliation(s)
- Johannes Burtscher
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Tom Citherlet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Alba Camacho-Cardenosa
- Department of Physical Education and Sports, Faculty of Sports Science, Sport and Health University Research Institute (iMUDS), University of Granada, Granada, Spain
| | - Marta Camacho-Cardenosa
- Clinical Management Unit of Endocrinology and Nutrition - GC17, Maimónides Biomedical Research Institute of Cordoba (IMIBIC), Reina Sofía University Hospital, Córdoba, Spain
| | - Antoine Raberin
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Bastien Krumm
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Erich Hohenauer
- Rehabilitation and Exercise Science Laboratory (RES lab), Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart, Switzerland
- International University of Applied Sciences THIM, Landquart, Switzerland
- Department of Neurosciences and Movement Science, University of Fribourg, Fribourg, Switzerland
| | - Margit Egg
- Institute of Zoology, University of Innsbruck, Innsbruck, Austria
| | - Mona Lichtblau
- Department of Pulmonology, University Hospital Zurich, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
| | - Julian Müller
- Department of Pulmonology, University Hospital Zurich, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
| | - Elena A Rybnikova
- Pavlov Institute of Physiology, Russian Academy of Sciences, St Petersburg, Russia
| | - Hannes Gatterer
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
- Institute for Sports Medicine, Alpine Medicine and Health Tourism (ISAG), UMIT TIROL-Private University for Health Sciences and Health Technology, Hall in Tirol, Austria
| | - Tadej Debevec
- Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia
- Department of Automatics, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Sebastien Baillieul
- Service Universitaire de Pneumologie Physiologie, University of Grenoble Alpes, Inserm, Grenoble, France
| | | | - Tom Behrendt
- Chair Health and Physical Activity, Department of Sport Science, Institute III, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Lutz Schega
- Chair Health and Physical Activity, Department of Sport Science, Institute III, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Hannelore Ehrenreich
- Clinical Neuroscience, University Medical Center and Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Grégoire P Millet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Max Gassmann
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zürich, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- Universidad Peruana Cayetano Heredia (UPCH), Lima, Peru
| | - Christoph Schwarzer
- Institute of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - Oleg Glazachev
- Department of Normal Physiology, N.V. Sklifosovsky Institute of Clinical Medicine, I. M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Olivier Girard
- School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Crawley, Western Australia, Australia
| | - Sophie Lalande
- Department of Kinesiology and Health Education, University of Texas at Austin, Austin, TX, USA
| | - Michael Hamlin
- Department of Tourism, Sport and Society, Lincoln University, Christchurch, New Zealand
| | - Michele Samaja
- Department of Health Science, University of Milan, Milan, Italy
| | - Katharina Hüfner
- Department of Psychiatry, Psychotherapy, Psychosomatics and Medical Psychology, University Hospital for Psychiatry II, Medical University of Innsbruck, Innsbruck, Austria
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Gino Panza
- The Department of Health Care Sciences, Program of Occupational Therapy, Wayne State University, Detroit, MI, USA
- John D. Dingell VA Medical Center Detroit, Detroit, MI, USA
| | - Robert T Mallet
- Department of Physiology & Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
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4
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Panza GS, Kissane DM, Puri S, Mateika JH. The hypoxic ventilatory response and hypoxic burden are predictors of the magnitude of ventilatory long-term facilitation in humans. J Physiol 2023; 601:4611-4623. [PMID: 37641466 PMCID: PMC11006398 DOI: 10.1113/jp285192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 08/16/2023] [Indexed: 08/31/2023] Open
Abstract
Mild intermittent hypoxia initiates progressive augmentation (PA) and ventilatory long-term facilitation (vLTF) in humans. The magnitude of these forms of plasticity might be influenced by anthropometric and physiological variables, as well as protocol elements. However, the impact of many of these variables on the magnitude of respiratory plasticity has not been established in humans. A meta-analysis was completed using anthropometric and physiological variables obtained from 124 participants that completed one of three intermittent hypoxia protocols. Simple correlations between the aggregate variables and the magnitude of PA and vLTF standardized to baseline was completed. Thereafter, the variables correlated to PA or vLTF were input into a multilinear regression equation. Baseline measures of the hypoxic ventilatory response was the sole predictor of PA (R = 0.370, P = 0.012). Similarly, this variable along with the hypoxic burden predicted the magnitude of vLTF (R = 0.546, P < 0.006 for both variables). In addition, the magnitude of PA was strongly correlated to vLTF (R = 0.617, P < 0.001). Anthropometric measures do not predict the magnitude of PA and vLTF in humans. Alternatively, the hypoxic ventilatory response was the sole predictor of PA, and in combination with the hypoxic burden, predicted the magnitude of vLTF. These influences should be considered in the design of mild intermittent hypoxia protocol studies in humans. Moreover, the strong correlation between PA and vLTF suggests that a common mechanistic pathway may have a role in the initiation of these forms of plasticity. KEY POINTS: Mild intermittent hypoxia initiates progressive augmentation (PA) and ventilatory long-term facilitation (vLTF) in humans. Many of the anthropometric and physiological variables that could impact the magnitude of these forms of plasticity are unknown. Anthropometric and physiological variables were measured from a total of 124 participants that completed one of three distinct intermittent hypoxia protocols. The variables correlated to PA or vLTF were input into a multilinear regression analysis. The hypoxic ventilatory response was the sole predictor of PA, while this variable in addition to the average hypoxic burden predicted the magnitude of vLTF. A strong correlation between PA and vLTF was also revealed. These influences should be considered in the design of mild intermittent hypoxia protocol studies in humans. Moreover, the strong correlation between PA and vLTF suggests that a common mechanistic pathway may have a role in the initiation of these forms of plasticity.
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Affiliation(s)
- Gino S Panza
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, USA
- Department of Health Care Sciences, Program of Occupational Therapy, Wayne State University, Detroit, MI, USA
| | - Dylan M Kissane
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, USA
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Shipra Puri
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, USA
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Jason H Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, USA
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
- Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI, USA
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5
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Marciante AB, Seven YB, Kelly MN, Perim RR, Mitchell GS. Magnitude and Mechanism of Phrenic Long-term Facilitation Shift Between Daily Rest Versus Active Phase. FUNCTION 2023; 4:zqad041. [PMID: 37753182 PMCID: PMC10519274 DOI: 10.1093/function/zqad041] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 09/28/2023] Open
Abstract
Plasticity is a fundamental property of the neural system controlling breathing. One key example of respiratory motor plasticity is phrenic long-term facilitation (pLTF), a persistent increase in phrenic nerve activity elicited by acute intermittent hypoxia (AIH). pLTF can arise from distinct cell signaling cascades initiated by serotonin versus adenosine receptor activation, respectively, and interact via powerful cross-talk inhibition. Here, we demonstrate that the daily rest/active phase and the duration of hypoxic episodes within an AIH protocol have profound impact on the magnitude and mechanism of pLTF due to shifts in serotonin/adenosine balance. Using the historical "standard" AIH protocol (3, 5-min moderate hypoxic episodes), we demonstrate that pLTF magnitude is unaffected by exposure in the midactive versus midrest phase, yet the mechanism driving pLTF shifts from serotonin-dominant (midrest) to adenosine-dominant (midactive). This mechanistic "flip" results from combined influences of hypoxia-evoked adenosine release and daily fluctuations in basal spinal adenosine. Since AIH evokes less adenosine with shorter (15, 1-min) hypoxic episodes, midrest pLTF is amplified due to diminished adenosine constraint on serotonin-driven plasticity; in contrast, elevated background adenosine during the midactive phase suppresses serotonin-dominant pLTF. These findings demonstrate the importance of the serotonin/adenosine balance in regulating the amplitude and mechanism of AIH-induced pLTF. Since AIH is emerging as a promising therapeutic modality to restore respiratory and nonrespiratory movements in people with spinal cord injury or ALS, knowledge of how time-of-day and hypoxic episode duration impact the serotonin/adenosine balance and the magnitude and mechanism of pLTF has profound biological, experimental, and translational implications.
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Affiliation(s)
- Alexandria B Marciante
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Yasin B Seven
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Mia N Kelly
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Raphael R Perim
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Gordon S Mitchell
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
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6
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Michel-Flutot P, Lane MA, Lepore AC, Vinit S. Therapeutic Strategies Targeting Respiratory Recovery after Spinal Cord Injury: From Preclinical Development to Clinical Translation. Cells 2023; 12:1519. [PMID: 37296640 PMCID: PMC10252981 DOI: 10.3390/cells12111519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 05/15/2023] [Accepted: 05/29/2023] [Indexed: 06/12/2023] Open
Abstract
High spinal cord injuries (SCIs) lead to permanent functional deficits, including respiratory dysfunction. Patients living with such conditions often rely on ventilatory assistance to survive, and even those that can be weaned continue to suffer life-threatening impairments. There is currently no treatment for SCI that is capable of providing complete recovery of diaphragm activity and respiratory function. The diaphragm is the main inspiratory muscle, and its activity is controlled by phrenic motoneurons (phMNs) located in the cervical (C3-C5) spinal cord. Preserving and/or restoring phMN activity following a high SCI is essential for achieving voluntary control of breathing. In this review, we will highlight (1) the current knowledge of inflammatory and spontaneous pro-regenerative processes occurring after SCI, (2) key therapeutics developed to date, and (3) how these can be harnessed to drive respiratory recovery following SCIs. These therapeutic approaches are typically first developed and tested in relevant preclinical models, with some of them having been translated into clinical studies. A better understanding of inflammatory and pro-regenerative processes, as well as how they can be therapeutically manipulated, will be the key to achieving optimal functional recovery following SCIs.
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Affiliation(s)
- Pauline Michel-Flutot
- END-ICAP, UVSQ, Inserm, Université Paris-Saclay, 78000 Versailles, France;
- Department of Neuroscience, Jefferson Synaptic Biology Center, Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA;
| | - Michael A. Lane
- Marion Murray Spinal Cord Research Center, Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA;
| | - Angelo C. Lepore
- Department of Neuroscience, Jefferson Synaptic Biology Center, Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA;
| | - Stéphane Vinit
- END-ICAP, UVSQ, Inserm, Université Paris-Saclay, 78000 Versailles, France;
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7
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Ostrowski D, Heesch CM, Kline DD, Hasser EM. Nucleus tractus solitarii is required for the development and maintenance of phrenic and sympathetic long-term facilitation after acute intermittent hypoxia. Front Physiol 2023; 14:1120341. [PMID: 36846346 PMCID: PMC9949380 DOI: 10.3389/fphys.2023.1120341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 01/26/2023] [Indexed: 02/11/2023] Open
Abstract
Exposure to acute intermittent hypoxia (AIH) induces prolonged increases (long term facilitation, LTF) in phrenic and sympathetic nerve activity (PhrNA, SNA) under basal conditions, and enhanced respiratory and sympathetic responses to hypoxia. The mechanisms and neurocircuitry involved are not fully defined. We tested the hypothesis that the nucleus tractus solitarii (nTS) is vital to augmentation of hypoxic responses and the initiation and maintenance of elevated phrenic (p) and splanchnic sympathetic (s) LTF following AIH. nTS neuronal activity was inhibited by nanoinjection of the GABAA receptor agonist muscimol before AIH exposure or after development of AIH-induced LTF. AIH but not sustained hypoxia induced pLTF and sLTF with maintained respiratory modulation of SSNA. nTS muscimol before AIH increased baseline SSNA with minor effects on PhrNA. nTS inhibition also markedly blunted hypoxic PhrNA and SSNA responses, and prevented altered sympathorespiratory coupling during hypoxia. Inhibiting nTS neuronal activity before AIH exposure also prevented the development of pLTF during AIH and the elevated SSNA after muscimol did not increase further during or following AIH exposure. Furthermore, nTS neuronal inhibition after the development of AIH-induced LTF substantially reversed but did not eliminate the facilitation of PhrNA. Together these findings demonstrate that mechanisms within the nTS are critical for initiation of pLTF during AIH. Moreover, ongoing nTS neuronal activity is required for full expression of sustained elevations in PhrNA following exposure to AIH although other regions likely also are important. Together, the data indicate that AIH-induced alterations within the nTS contribute to both the development and maintenance of pLTF.
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Affiliation(s)
- Daniela Ostrowski
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, United States,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States,Department of Biology, Truman State University, Kirksville, MO, United States
| | - Cheryl M. Heesch
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, United States,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States
| | - David D. Kline
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, United States,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States,Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, United States
| | - Eileen M. Hasser
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, United States,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States,Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, United States,*Correspondence: Eileen M. Hasser,
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8
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Yang L, Cheng Y, Zhu Y, Cui L, Li X. The Serotonergic System and Amyotrophic Lateral Sclerosis: A Review of Current Evidence. Cell Mol Neurobiol 2023:10.1007/s10571-023-01320-0. [PMID: 36729314 DOI: 10.1007/s10571-023-01320-0] [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: 08/03/2022] [Accepted: 01/18/2023] [Indexed: 02/03/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the premature death of motor neurons. Serotonin (5-HT) is a crucial neurotransmitter, and its dysfunction, whether as a contributor or by-product, has been implicated in ALS pathogenesis. Here, we summarize current evidence linking serotonergic alterations to ALS, including results from post-mortem and neuroimaging studies, biofluid testing, and studies of ALS animal models. We also discuss the possible role of 5-HT in modulating some important mechanisms of ALS (i.e. glutamate excitotoxity and neuroinflammation) and in regulating ALS phenotypes (i.e. breathing dysfunction and metabolic defects). Finally, we discuss the promise and limitations of the serotonergic system as a target for the development of ALS biomarkers and therapeutic approaches. However, due to a relative paucity of data and standardized methodologies in previous studies, proper interpretation of existing results remains a challenge. Future research is needed to unravel the mechanisms linking serotonergic pathways and ALS and to provide valid, reproducible, and translatable findings.
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Affiliation(s)
- Lu Yang
- Department of Neurology, Peking Union Medical College Hospital (PUMCH), The Transformation Medical Center of PUMC, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, 100005, China
| | - Yanfei Cheng
- Department of Neurology, Peking Union Medical College Hospital (PUMCH), The Transformation Medical Center of PUMC, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, 100005, China
| | - Yicheng Zhu
- Department of Neurology, Peking Union Medical College Hospital (PUMCH), The Transformation Medical Center of PUMC, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, 100005, China.,Neuroscience Center, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, China
| | - Liying Cui
- Department of Neurology, Peking Union Medical College Hospital (PUMCH), The Transformation Medical Center of PUMC, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, 100005, China.,Neuroscience Center, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, China
| | - Xiaoguang Li
- Department of Neurology, Peking Union Medical College Hospital (PUMCH), The Transformation Medical Center of PUMC, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, 100005, China. .,Neuroscience Center, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, China.
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9
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Mitchell GS, Baker TL. Respiratory neuroplasticity: Mechanisms and translational implications of phrenic motor plasticity. HANDBOOK OF CLINICAL NEUROLOGY 2022; 188:409-432. [PMID: 35965036 DOI: 10.1016/b978-0-323-91534-2.00016-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Widespread appreciation that neuroplasticity is an essential feature of the neural system controlling breathing has emerged only in recent years. In this chapter, we focus on respiratory motor plasticity, with emphasis on the phrenic motor system. First, we define related but distinct concepts: neuromodulation and neuroplasticity. We then focus on mechanisms underlying two well-studied models of phrenic motor plasticity: (1) phrenic long-term facilitation following brief exposure to acute intermittent hypoxia; and (2) phrenic motor facilitation after prolonged or recurrent bouts of diminished respiratory neural activity. Advances in our understanding of these novel and important forms of plasticity have been rapid and have already inspired translation in multiple respects: (1) development of novel therapeutic strategies to preserve/restore breathing function in humans with severe neurological disorders, such as spinal cord injury and amyotrophic lateral sclerosis; and (2) the discovery that similar plasticity also occurs in nonrespiratory motor systems. Indeed, the realization that similar plasticity occurs in respiratory and nonrespiratory motor neurons inspired clinical trials to restore leg/walking and hand/arm function in people living with chronic, incomplete spinal cord injury. Similar application may be possible to other clinical disorders that compromise respiratory and non-respiratory movements.
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Affiliation(s)
- Gordon S Mitchell
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL, United States.
| | - Tracy L Baker
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI, United States
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10
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Dempsey JA, Neder JA, Phillips DB, O'Donnell DE. The physiology and pathophysiology of exercise hyperpnea. HANDBOOK OF CLINICAL NEUROLOGY 2022; 188:201-232. [PMID: 35965027 DOI: 10.1016/b978-0-323-91534-2.00001-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In health, the near-eucapnic, highly efficient hyperpnea during mild-to-moderate intensity exercise is driven by three obligatory contributions, namely, feedforward central command from supra-medullary locomotor centers, feedback from limb muscle afferents, and respiratory CO2 exchange (V̇CO2). Inhibiting each of these stimuli during exercise elicits a reduction in hyperpnea even in the continuing presence of the other major stimuli. However, the relative contribution of each stimulus to the hyperpnea remains unknown as does the means by which V̇CO2 is sensed. Mediation of the hyperventilatory response to exercise in health is attributed to the multiple feedback and feedforward stimuli resulting from muscle fatigue. In patients with COPD, diaphragm EMG amplitude and its relation to ventilatory output are used to decipher mechanisms underlying the patients' abnormal ventilatory responses, dynamic lung hyperinflation and dyspnea during exercise. Key contributions to these exercise-limiting responses across the spectrum of COPD severity include high dead space ventilation, an excessive neural drive to breathe and highly fatigable limb muscles, together with mechanical constraints on ventilation. Major controversies concerning control of exercise hyperpnea are discussed along with the need for innovative research to uncover the link of metabolism to breathing in health and disease.
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Affiliation(s)
- Jerome A Dempsey
- John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, University of Wisconsin-Madison, Madison, WI, United States.
| | - J Alberto Neder
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Campus, Kingston, ON, Canada
| | - Devin B Phillips
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Campus, Kingston, ON, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Campus, Kingston, ON, Canada
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Sandhu MS, Rymer WZ. Brief exposure to systemic hypoxia enhances plasticity of the central nervous system in spinal cord injured animals and man. Curr Opin Neurol 2021; 34:819-824. [PMID: 34545014 DOI: 10.1097/wco.0000000000000990] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW We have known for many decades that animals that sustain injuries to the neuraxis, which result in respiratory impairment, are able to develop rapid neural compensation for these injuries. This compensation, which is linked to the systemic hypoxia resulting from damage to the respiratory apparatus, is a potent manifestation of neural plasticity. Hypoxia-induced plasticity is also applicable to somatic neural systems that regulate motor activity in extremity muscles. We report on recent developments in our understanding of the mechanisms underlying this seemingly beneficial action of acute intermittent hypoxia (AIH). RECENT FINDINGS AIH improves breathing in animal models of spinal cord injury, and increases strength and endurance in individuals with incomplete spinal injuries. The role of AIH as a therapeutic intervention remains to be confirmed but it has proved to be well tolerated for use in humans with no adverse effects reported to date. The effects of AIH emerge rapidly and persist for several hours raising the possibility that the intervention may serve as a priming mechanism for facilitating rehabilitation and promoting recovery after neurologic injury in man. SUMMARY AIH is emerging as a potent and relatively inexpensive modality for inducing neuroplasticity, so it may prove feasible to use AIH in a clinical setting.
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Affiliation(s)
- Milap S Sandhu
- Shirley Ryan AbilityLab
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois, USA
| | - William Z Rymer
- Shirley Ryan AbilityLab
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois, USA
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Nanduri J, Wang N, Wang BL, Prabhakar NR. Lysine demethylase KDM6B regulates HIF-1α-mediated systemic and cellular responses to intermittent hypoxia. Physiol Genomics 2021; 53:385-394. [PMID: 34297635 PMCID: PMC8887999 DOI: 10.1152/physiolgenomics.00045.2021] [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: 02/02/2023] Open
Abstract
Intermittent hypoxia (IH) is a hallmark manifestation of obstructive sleep apnea (OSA). Rodents treated with IH exhibit hypertension. Hypoxia-inducible factor (HIF)-1-dependent transcriptional activation of NADPH oxidases (Nox) and the resulting increase in reactive oxygen species (ROS) levels is a major molecular mechanism underlying IH/OSA-induced hypertension. Jumanji C (JmjC)-containing histone lysine demethylases (JmjC-KDMs) are coactivators of HIF-1-dependent transcriptional activation. In the present study, we tested the hypothesis that JmjC-KDMs are required for IH-evoked HIF-1 transcriptional activation of Nox4 and the ensuing hypertension. Studies were performed on pheochromocytoma (PC)12 cells and rats. IH increased KDM6B protein and enzyme activity in PC12 cells in an HIF-1-independent manner as evidenced by unaltered KDM6B activation by IH in HIF-1α shRNA-treated cells. Cells treated with IH showed increased HIF-1-dependent Nox4 transcription as indicated by increased HIF-1α binding to hypoxia-responsive element (HRE) sequence of the Nox4 gene promoter demonstrated by chromatin immunoprecipitation (ChiP) assay. Pharmacological blockade of KDM6B with GSKJ4, a specific KDM6 inhibitor, or genetic silencing of KDM6B with shRNA abolished IH-induced Nox4 transcriptional activation by blocking HIF-1α binding to the promoter of the Nox4 gene. Treating IH-exposed rats with GSKJ4 showed: 1) absence of KDM6B activation and HIF-1-dependent Nox4 transcription in the adrenal medullae, and 2) absence of elevated plasma catecholamines and hypertension. Collectively, these findings indicate that KDM6B functions as a coactivator of HIF-1-mediated Nox4 transactivation and demonstrates a hitherto uncharacterized role for KDMs in IH-induced hypertension by HIF-1.
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Affiliation(s)
- Jayasri Nanduri
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, The University of Chicago, Chicago, Illinois
| | - Ning Wang
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, The University of Chicago, Chicago, Illinois
| | - Benjamin L. Wang
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, The University of Chicago, Chicago, Illinois
| | - Nanduri R. Prabhakar
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, The University of Chicago, Chicago, Illinois
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Acute intermittent hypoxia evokes ventilatory long-term facilitation and active expiration in unanesthetized rats. Respir Physiol Neurobiol 2021; 294:103768. [PMID: 34343692 DOI: 10.1016/j.resp.2021.103768] [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: 02/06/2021] [Revised: 07/23/2021] [Accepted: 07/29/2021] [Indexed: 11/23/2022]
Abstract
Acute intermittent hypoxia (AIH) modifies the functioning of the respiratory network, causing respiratory motor facilitation in anesthetized animals and a compensatory increase in pulmonary ventilation in freely behaving animals. However, it is still unclear whether the ventilatory facilitation induced by AIH in unanesthetized animals is associated with changes in the respiratory pattern. We found that Holtzman male rats (80-150 g) exposed to AIH (10 × 6% O2 for 30-40 s every 5 min, n = 9) exhibited a prolonged (30 min) increase in baseline minute ventilation (P < 0.05) compared to control animals (n = 13), combined with the occurrence of late expiratory peak flow events, suggesting the presence of active expiration. The increase in ventilation after AIH was also accompanied by reductions in arterial CO2 and body temperature (n = 5-6, P < 0.05). The systemic treatment with ketanserin (a 5-HT2 receptor antagonist) before AIH prevented the changes in ventilation and active expiration (n = 11) but potentiated the hypothermic response (n = 5, P < 0.05) when compared to appropriate control rats (n = 13). Our findings indicate that the ventilatory long-term facilitation elicited by AIH exposure in unanesthetized rats is linked to the generation of active expiration by mechanisms that may depend on the activation of serotonin receptors. In contrast, the decrease in body temperature induced by AIH may not require 5-HT2 receptor activation.
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