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Jensen VN, Huffman EE, Jalufka FL, Pritchard AL, Baumgartner S, Walling I, C. Gibbs H, McCreedy DA, Alilain WJ, Crone SA. V2a neurons restore diaphragm function in mice following spinal cord injury. Proc Natl Acad Sci U S A 2024; 121:e2313594121. [PMID: 38442182 PMCID: PMC10945804 DOI: 10.1073/pnas.2313594121] [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: 08/07/2023] [Accepted: 01/15/2024] [Indexed: 03/07/2024] Open
Abstract
The specific roles that different types of neurons play in recovery from injury is poorly understood. Here, we show that increasing the excitability of ipsilaterally projecting, excitatory V2a neurons using designer receptors exclusively activated by designer drugs (DREADDs) restores rhythmic bursting activity to a previously paralyzed diaphragm within hours, days, or weeks following a C2 hemisection injury. Further, decreasing the excitability of V2a neurons impairs tonic diaphragm activity after injury as well as activation of inspiratory activity by chemosensory stimulation, but does not impact breathing at rest in healthy animals. By examining the patterns of muscle activity produced by modulating the excitability of V2a neurons, we provide evidence that V2a neurons supply tonic drive to phrenic circuits rather than increase rhythmic inspiratory drive at the level of the brainstem. Our results demonstrate that the V2a class of neurons contribute to recovery of respiratory function following injury. We propose that altering V2a excitability is a potential strategy to prevent respiratory motor failure and promote recovery of breathing following spinal cord injury.
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Affiliation(s)
- Victoria N. Jensen
- Neuroscience Graduate Program, University of Cincinnati College of Medicine, Cincinnati, OH45219
| | - Emily E. Huffman
- Department of Neuroscience, University of Kentucky College of Medicine, Lexington, KY40536
- Spinal Cord and Brain Injury Research Center, University of Kentucky College of Medicine, Lexington, KY40536
| | - Frank L. Jalufka
- Department of Biology, Texas A&M University, College Station, TX77843
| | - Anna L. Pritchard
- Department of Biomedical Engineering, Texas A&M University, College Station, TX77843
| | - Sarah Baumgartner
- Division of Neurosurgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH45229
| | - Ian Walling
- Neuroscience Graduate Program, University of Cincinnati College of Medicine, Cincinnati, OH45219
- Medical Scientist Training Program, University of Cincinnati College of Medicine, Cincinnati, OH45267
| | - Holly C. Gibbs
- Department of Biomedical Engineering, Texas A&M University, College Station, TX77843
- Microscopy and Imaging Center, Texas A&M University, College Station, TX77843
| | - Dylan A. McCreedy
- Department of Biology, Texas A&M University, College Station, TX77843
- Department of Biomedical Engineering, Texas A&M University, College Station, TX77843
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX77843
| | - Warren J. Alilain
- Department of Neuroscience, University of Kentucky College of Medicine, Lexington, KY40536
- Spinal Cord and Brain Injury Research Center, University of Kentucky College of Medicine, Lexington, KY40536
| | - Steven A. Crone
- Division of Neurosurgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH45229
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH45229
- Department of Neurosurgery, University of Cincinnati College of Medicine, Cincinnati, OH45267
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2
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Idlett-Ali S, Kloefkorn H, Goolsby W, Hochman S. Relating Spinal Injury-Induced Neuropathic Pain and Spontaneous Afferent Activity to Sleep and Respiratory Dysfunction. J Neurotrauma 2023; 40:2654-2666. [PMID: 37212274 PMCID: PMC11093096 DOI: 10.1089/neu.2022.0305] [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] [Indexed: 05/23/2023] Open
Abstract
Abstract Spinal cord injury (SCI) can induce dysfunction in a multitude of neural circuits including those that lead to impaired sleep, respiratory dysfunction, and neuropathic pain. We used a lower thoracic rodent contusion SCI model of neuropathic pain that has been shown to associate with increased spontaneous activity in primary afferents and hindlimb mechanosensory stimulus hypersensitivity. Here we paired capture of these variables with chronic capture of three state sleep and respiration to more broadly understand SCI-induced physiological dysfunction and to assess possible interrelations. Noncontact electric field sensors were embedded into home cages to non-invasively capture the temporal evolution of sleep and respiration changes for six weeks after SCI in naturally behaving mice. Hindlimb mechanosensitivity was assessed weekly, and terminal experiments measured primary afferent spontaneous activity in situ from intact lumbar dorsal root ganglia (DRG). We observed that SCI led to increased spontaneous primary afferent activity (both firing rate and the number of spontaneously active DRGs) that correlated with increased respiratory rate variability and measures of sleep fragmentation. This is the first study to measure and link sleep dysfunction and variability in respiratory rate in a SCI model of neuropathic pain, and thereby provide broader insight into the magnitude of overall stress burden initiated by neural circuit dysfunction after SCI.
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Affiliation(s)
- Shaquia Idlett-Ali
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA
- Department of Physiology, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Heidi Kloefkorn
- Department of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, Oregon, USA
| | - William Goolsby
- Department of Physiology, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Shawn Hochman
- Department of Physiology, School of Medicine, Emory University, Atlanta, Georgia, USA
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3
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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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4
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Randelman M, Zholudeva LV, Vinit S, Lane MA. Respiratory Training and Plasticity After Cervical Spinal Cord Injury. Front Cell Neurosci 2021; 15:700821. [PMID: 34621156 PMCID: PMC8490715 DOI: 10.3389/fncel.2021.700821] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 08/11/2021] [Indexed: 12/30/2022] Open
Abstract
While spinal cord injuries (SCIs) result in a vast array of functional deficits, many of which are life threatening, the majority of SCIs are anatomically incomplete. Spared neural pathways contribute to functional and anatomical neuroplasticity that can occur spontaneously, or can be harnessed using rehabilitative, electrophysiological, or pharmacological strategies. With a focus on respiratory networks that are affected by cervical level SCI, the present review summarizes how non-invasive respiratory treatments can be used to harness this neuroplastic potential and enhance long-term recovery. Specific attention is given to "respiratory training" strategies currently used clinically (e.g., strength training) and those being developed through pre-clinical and early clinical testing [e.g., intermittent chemical stimulation via altering inhaled oxygen (hypoxia) or carbon dioxide stimulation]. Consideration is also given to the effect of training on non-respiratory (e.g., locomotor) networks. This review highlights advances in this area of pre-clinical and translational research, with insight into future directions for enhancing plasticity and improving functional outcomes after SCI.
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Affiliation(s)
- Margo Randelman
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States.,Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Lyandysha V Zholudeva
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States.,Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, United States.,Gladstone Institutes, San Francisco, CA, United States
| | - Stéphane Vinit
- INSERM, END-ICAP, Université Paris-Saclay, UVSQ, Versailles, France
| | - Michael A Lane
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States.,Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, United States
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5
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Gonzalez-Rothi EJ, Lee KZ. Intermittent hypoxia and respiratory recovery in pre-clinical rodent models of incomplete cervical spinal cord injury. Exp Neurol 2021; 342:113751. [PMID: 33974878 DOI: 10.1016/j.expneurol.2021.113751] [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] [Received: 12/11/2020] [Revised: 04/24/2021] [Accepted: 05/06/2021] [Indexed: 10/21/2022]
Abstract
Impaired respiratory function is a common and devastating consequence of cervical spinal cord injury. Accordingly, the development of safe and effective treatments to restore breathing function is critical. Acute intermittent hypoxia has emerged as a promising therapeutic strategy to treat respiratory insufficiency in individuals with spinal cord injury. Since the original report by Bach and Mitchell (1996) concerning long-term facilitation of phrenic motor output elicited by brief, episodic exposure to reduced oxygen, a series of studies in animal models have led to the realization that acute intermittent hypoxia may have tremendous potential for inducing neuroplasticity and functional recovery in the injured spinal cord. Advances in our understanding of the neurobiology of acute intermittent hypoxia have prompted us to begin to explore its effects in human clinical studies. Here, we review the basic neurobiology of the control of breathing and the pathophysiology and respiratory consequences of two common experimental models of incomplete cervical spinal cord injury (i.e., high cervical hemisection and mid-cervical contusion). We then discuss the impact of acute intermittent hypoxia on respiratory motor function in these models: work that has laid the foundation for translation of this promising therapeutic strategy to clinical populations. Lastly, we examine the limitations of these animal models and intermittent hypoxia and discuss how future work in animal models may further advance the translation and therapeutic efficacy of this treatment.
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Affiliation(s)
- Elisa J Gonzalez-Rothi
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Kun-Ze Lee
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan; Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, Taiwan.
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6
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Jesus I, Michel-Flutot P, Deramaudt TB, Paucard A, Vanhee V, Vinit S, Bonay M. Effects of aerobic exercise training on muscle plasticity in a mouse model of cervical spinal cord injury. Sci Rep 2021; 11:112. [PMID: 33420246 PMCID: PMC7794462 DOI: 10.1038/s41598-020-80478-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 12/21/2020] [Indexed: 02/06/2023] Open
Abstract
Cervical spinal cord injury (SCI) results in permanent life-altering motor and respiratory deficits. Other than mechanical ventilation for respiratory insufficiency secondary to cervical SCI, effective treatments are lacking and the development of animal models to explore new therapeutic strategies are needed. The aim of this work was to demonstrate the feasibility of using a mouse model of partial cervical spinal hemisection at the second cervical metameric segment (C2) to investigate the impact of 6 weeks training on forced exercise wheel system on locomotor/respiratory plasticity muscles. To measure run capacity locomotor and respiratory functions, incremental exercise tests and diaphragmatic electromyography were done. In addition, muscle fiber type composition and capillary distribution were assessed at 51 days following chronic C2 injury in diaphragm, extensor digitorum communis (EDC), tibialis anterior (TA) and soleus (SOL) muscles. Six-week exercise training increased the running capacity of trained SCI mice. Fiber type composition in EDC, TA and SOL muscles was not modified by our protocol of exercise. The vascularization was increased in all muscle limbs in SCI trained group. No increase in diaphragmatic electromyography amplitude of the diaphragm muscle on the side of SCI was observed, while the contraction duration was significantly decreased in sedentary group compared to trained group. Cross-sectional area of type IIa myofiber in the contralateral diaphragm side of SCI was smaller in trained group. Fiber type distribution between contralateral and ipsilateral diaphragm in SCI sedentary group was affected, while no difference was observed in trained group. In addition, the vascularization of the diaphragm side contralateral to SCI was increased in trained group. All these results suggest an increase in fatigue resistance and a contribution to the running capacity in SCI trained group. Our exercise protocol could be a promising non-invasive strategy to sustain locomotor and respiratory muscle plasticity following SCI.
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Affiliation(s)
- Isley Jesus
- Inserm, END-ICAP, Université Paris-Saclay, UVSQ, 78000, Versailles, France
| | | | | | - Alexia Paucard
- Inserm, END-ICAP, Université Paris-Saclay, UVSQ, 78000, Versailles, France
| | - Valentin Vanhee
- Inserm, END-ICAP, Université Paris-Saclay, UVSQ, 78000, Versailles, France
| | - Stéphane Vinit
- Inserm, END-ICAP, Université Paris-Saclay, UVSQ, 78000, Versailles, France
| | - Marcel Bonay
- Inserm, END-ICAP, Université Paris-Saclay, UVSQ, 78000, Versailles, France.
- Service de Physiologie-Explorations Fonctionnelles; Hôpital Ambroise Paré, Assistance Publique-Hôpitaux de Paris, Boulogne, France.
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7
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Receno CN, Eassa BE, Cunningham CM, DeRuisseau LR. Young and middle-aged mouse breathing behavior during the light and dark cycles. Physiol Rep 2020; 7:e14060. [PMID: 31004390 PMCID: PMC6474843 DOI: 10.14814/phy2.14060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 03/13/2019] [Indexed: 12/21/2022] Open
Abstract
Unrestrained barometric plethysmography is a common method used for characterizing breathing patterns in small animals. One source of variation between unrestrained barometric plethysmography studies is the segment of baseline. Baseline may be analyzed as a predetermined time‐point, or using tailored segments when each animal is visually calm. We compared a quiet, minimally active (no sniffing/grooming) breathing segment to a predetermined time‐point at 1 h for baseline measurements in young and middle‐aged mice during the dark and light cycles. Additionally, we evaluated the magnitude of change for gas challenges based on these two baseline segments. C57BL/6JEiJ x C3Sn.BliA‐Pde6b+/DnJ male mice underwent unrestrained barometric plethysmography with the following baselines used to determine breathing frequency, tidal volume (VT) and minute ventilation (VE): (1) 30‐sec of quiet breathing and (2) a 10‐min period from 50 to 60 min. Animals were also exposed to 10 min of hypoxic (10% O2, balanced N2), hypercapnic (5% CO2, balanced air) and hypoxic hypercapnic (10% O2, 5% CO2, balanced N2) gas. Both frequency and VE were higher during the predetermined 10‐min baseline versus the 30‐sec baseline, while VT was lower (P < 0.05). However, VE/VO2 was similar between the baseline time segments (P > 0.05) in an analysis of one cohort. During baseline, dark cycle testing had increased VT values versus those in the light (P < 0.05). For gas challenges, both frequency and VE showed higher percent change from the 30‐sec baseline compared to the predetermined 10‐min baseline (P < 0.05), while VT showed a greater change from the 10‐min baseline (P < 0.05). Dark cycle hypoxic exposure resulted in larger percent change in breathing frequency versus the light cycle (P < 0.05). Overall, light and dark cycle pattern of breathing differences emerged along with differences between the 30‐sec behavior observational method versus a predetermined time segment for baseline.
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Affiliation(s)
- Candace N Receno
- Department of Biological Sciences, Le Moyne College, Syracuse, New York
| | - Brianna E Eassa
- Department of Biological Sciences, Le Moyne College, Syracuse, New York
| | - Caitlin M Cunningham
- Department of Mathematics, Statistics and Computer Science, Le Moyne College, Syracuse, New York
| | - Lara R DeRuisseau
- Department of Biological Sciences, Le Moyne College, Syracuse, New York
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8
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Wu MJ, Vinit S, Chen CL, Lee KZ. 5-HT7 Receptor Inhibition Transiently Improves Respiratory Function Following Daily Acute Intermittent Hypercapnic-Hypoxia in Rats With Chronic Midcervical Spinal Cord Contusion. Neurorehabil Neural Repair 2020; 34:333-343. [DOI: 10.1177/1545968320905806] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Background. Intermittent hypoxia can induce respiratory neuroplasticity to enhance respiratory motor outputs following hypoxic treatment. This type of respiratory neuroplasticity is primarily mediated by the activation of Gq-protein-coupled 5-HT2 receptors and constrained by Gs-protein-coupled 5-HT7 receptors. Objective. The present study hypothesized that the blockade of 5-HT7 receptors can potentiate the effect of intermittent hypercapnic-hypoxia on respiratory function after cervical spinal cord contusion injury. Methods. The ventilatory behaviors of unanesthetized rats with midcervical spinal cord contusions were measured before, during, and after daily acute intermittent hypercapnic-hypoxia (10 episodes of 5 minutes of hypoxia [10% O2, 4% CO2, 86% N2] with 5 minutes of normoxia intervals for 5 days) at 8 weeks postinjury. On a daily basis, 5 minutes before intermittent hypercapnic-hypoxia, rats received either a 5-HT7 receptor antagonist (SB269970, 4 mg/kg, intraperitoneal) or a vehicle (dimethyl sulfoxide). Results. Treatment with intermittent hypercapnic-hypoxia induced a similar increase in tidal volume between rats that received SB269970 and those that received dimethyl sulfoxide within 60 minutes post-hypoxia on the first day. However, after 2 to 3 days of daily acute intermittent hypercapnic-hypoxia, the baseline tidal volumes of rats treated with SB269970 increased significantly. Conclusions. These results suggest that inhibiting the 5-HT7 receptor can transiently improve daily intermittent hypercapnic-hypoxia–induced tidal volume increase in midcervical spinal contused animals. Therefore, combining pharmacological treatment with rehabilitative intermittent hypercapnic-hypoxia training may be an effective strategy for synergistically enhancing respiratory neuroplasticity to improve respiratory function following chronic cervical spinal cord injury.
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Affiliation(s)
- Ming-Jane Wu
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Stéphane Vinit
- Université de Versailles Saint-Quentin-en-Yvelines, Montigny-le-Bretonneux, France
| | - Chun-Lin Chen
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Kun-Ze Lee
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
- Center for Neuroscience, National Sun Yat-sen University, Kaohsiung, Taiwan
- Institute of Medical Science and Technology, National Sun Yat-sen University, Kaohsiung, Taiwan
- Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, Taiwan
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9
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Mateika JH, Komnenov D, Pop A, Kuhn DM. Genetic depletion of 5-HT increases central apnea frequency and duration and dampens arousal but does not impact the circadian modulation of these variables. J Appl Physiol (1985) 2019; 126:1-10. [DOI: 10.1152/japplphysiol.00724.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We examined the impact of serotonin (5-HT) on the frequency and duration of central apneic events and the frequency of accompanying arousals during nonrapid and rapid eye movement (NREM and REM, respectively) sleep across the light/dark cycle. Electroencephalography, electromyography, core body temperature, and activity were recorded for 24 h following implantation of telemeters in wild-type (Tph2+/+) and tryptophan hydroxylase 2 knockout (Tph2−/−) male mice. The frequency and duration of central apneic events were increased, the number of apneic events coupled to an arousal was decreased, and the ventilatory sensitivity to hypoxia and hypercapnia was decreased in the Tph2−/− compared with the Tph2+/+ mice during NREM sleep. Apnea frequency and duration were similar in the Tph2−/− and Tph2+/+ mice during REM sleep. The duration of apneic events during REM compared with NREM sleep was similar in the Tph2−/− mice. In contrast, the duration was greater during REM sleep in the Tph2+/+ mice. Our results also revealed that apnea frequency was greater during the light compared with the dark cycle. Circadian modulation of this variable was evident in both the Tph2−/− and Tph2+/+ mice during NREM and REM sleep. We conclude that depletion of 5-HT increases the frequency and duration of central apneic events, dampens arousal, and blunts the ventilatory response to hypoxia and hypercapnia during NREM sleep but is not essential for the circadian modulation of these variables. NEW & NOTEWORTHY The presence of serotonin (5-HT) in the central nervous system diminishes the frequency of central apneic events. This neuromodulator also moderates the duration of central apneic events and promotes arousal from central events if they occur during nonrapid eye movement (NREM) sleep. However, 5-HT is not responsible for the circadian modulation of apnea frequency, which we found was greater during NREM sleep in the light compared with the dark cycle.
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Affiliation(s)
- Jason H. Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
- Department of Internal Medicine, Wayne State University School of Medicine, Detroit, Michigan
| | - Dragana Komnenov
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Alexandru Pop
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Donald M. Kuhn
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan
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10
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Mateika JH, Panza G, Alex R, El-Chami M. The impact of intermittent or sustained carbon dioxide on intermittent hypoxia initiated respiratory plasticity. What is the effect of these combined stimuli on apnea severity? Respir Physiol Neurobiol 2017; 256:58-66. [PMID: 29097171 DOI: 10.1016/j.resp.2017.10.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 10/13/2017] [Accepted: 10/21/2017] [Indexed: 11/28/2022]
Abstract
The following review explores the effect that intermittent or sustained hypercapnia coupled to intermittent hypoxia has on respiratory plasticity. The review explores published work which suggests that intermittent hypercapnia leads to long-term depression of respiration when administered in isolation and prevents the initiation of long-term facilitation when administered in combination with intermittent hypoxia. The review also explores the impact that sustained hypercapnia alone and in combination with intermittent hypoxia has on the magnitude of long-term facilitation. After exploring the outcomes linked to intermittent hypoxia/hypercapnia and intermittent hypoxia/sustained hypercapnia the translational relevance of the outcomes as it relates to breathing stability during sleep is addressed. The likelihood that naturally induced cycles of intermittent hypoxia, coupled to oscillations in carbon dioxide that range between hypocapnia and hypercapnia, do not initiate long-term facilitation is addressed. Moreover, the conditions under which intermittent hypoxia/sustained hypercapnia could serve to improve breathing stability and mitigate co-morbidities associated with sleep apnea are considered.
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Affiliation(s)
- Jason H Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States; Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI, 48201, United States.
| | - Gino Panza
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States
| | - Raichel Alex
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States
| | - Mohamad El-Chami
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States
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11
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Baillieul S, Chacaroun S, Doutreleau S, Detante O, Pépin JL, Verges S. Hypoxic conditioning and the central nervous system: A new therapeutic opportunity for brain and spinal cord injuries? Exp Biol Med (Maywood) 2017; 242:1198-1206. [PMID: 28585890 DOI: 10.1177/1535370217712691] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Central nervous system diseases are among the most disabling in the world. Neuroprotection and brain recovery from either acute or chronic neurodegeneration still represent a challenge in neurology and neurorehabilitation as pharmacology treatments are often insufficiently effective. Conditioning the central nervous system has been proposed as a potential non-pharmacological neuro-therapeutic. Conditioning refers to a procedure by which a potentially deleterious stimulus is applied near to but below the threshold of damage to the organism to increase resistance to the same or even different noxious stimuli given above the threshold of damage. Hypoxic conditioning has been investigated in several cellular and preclinical models and is now recognized as inducing endogenous mechanisms of neuroprotection. Ischemic, traumatic, or chronic neurodegenerative diseases can benefit from hypoxic conditioning strategies aiming at preventing the deleterious consequences or reducing the severity of the pathological condition (preconditioning) or aiming at inducing neuroplasticity and recovery (postconditioning) following central nervous system injury. Hypoxic conditioning can consist in single (sustained) or cyclical (intermittent, interspersed by short period of normoxia) hypoxia stimuli which duration range from few minutes to several hours and that can be repeated over several days or weeks. This mini-review addresses the existing evidence regarding the use of hypoxic conditioning as a potential innovating neuro-therapeutic modality to induce neuroprotection, neuroplasticity and brain recovery. This mini-review also emphasizes issues which remain to be clarified and future researches to be performed in the field. Impact statement Neuroprotection and brain recovery from either acute or chronic neurodegeneration still represent a challenge in neurology and neurorehabilitation. Hypoxic conditioning may represent a harmless and efficient non-pharmacological new therapeutic modality in the field of neuroprotection and neuroplasticity, as supported by many preclinical data. Animal studies provide clear evidence for neuroprotection and neuroplasticity induced by hypoxic conditioning in several models of neurological disorders. These studies show improved functional outcomes when hypoxic conditioning is applied and provides important information to translate this intervention to clinical practice. Some studies in humans provide encouraging data regarding the tolerance and therapeutic effects of hypoxic conditioning strategies. The main issues to address in future research include the definition of the appropriate hypoxic dose and pattern of exposure, the determination of relevant physiological biomarkers to assess the effects of the treatment and the evaluation of combined strategies involving hypoxic conditioning and other pharmacological or non-pharmacological treatments.
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Affiliation(s)
- S Baillieul
- 1 CHU Grenoble Alpes, Physiology, Sleep and Exercise Department, Grenoble F-38042, France.,2 INSERM, U1042, Grenoble F-38042, France.,3 HP2 Laboratory, Univ. Grenoble Alpes, Grenoble F-38042, France
| | - S Chacaroun
- 2 INSERM, U1042, Grenoble F-38042, France.,3 HP2 Laboratory, Univ. Grenoble Alpes, Grenoble F-38042, France
| | - S Doutreleau
- 1 CHU Grenoble Alpes, Physiology, Sleep and Exercise Department, Grenoble F-38042, France.,2 INSERM, U1042, Grenoble F-38042, France.,3 HP2 Laboratory, Univ. Grenoble Alpes, Grenoble F-38042, France
| | - O Detante
- 4 CHU Grenoble Alpes, Pôle Psychiatrie Neurologie, Stroke Unit, Grenoble F-38042, France.,5 Inserm U 836, Grenoble Institute of Neurosciences, Grenoble F-38042, France
| | - J L Pépin
- 1 CHU Grenoble Alpes, Physiology, Sleep and Exercise Department, Grenoble F-38042, France.,2 INSERM, U1042, Grenoble F-38042, France.,3 HP2 Laboratory, Univ. Grenoble Alpes, Grenoble F-38042, France
| | - S Verges
- 2 INSERM, U1042, Grenoble F-38042, France.,3 HP2 Laboratory, Univ. Grenoble Alpes, Grenoble F-38042, France
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12
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Zholudeva LV, Karliner JS, Dougherty KJ, Lane MA. Anatomical Recruitment of Spinal V2a Interneurons into Phrenic Motor Circuitry after High Cervical Spinal Cord Injury. J Neurotrauma 2017; 34:3058-3065. [PMID: 28548606 DOI: 10.1089/neu.2017.5045] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
More than half of all spinal cord injuries (SCIs) occur at the cervical level, often resulting in impaired respiration. Despite this devastating outcome, there is substantial evidence for endogenous neuroplasticity after cervical SCI. Spinal interneurons are widely recognized as being an essential anatomical component of this plasticity by contributing to novel neuronal pathways that can result in functional improvement. The identity of spinal interneurons involved with respiratory plasticity post-SCI, however, has remained largely unknown. Using a transgenic Chx10-eGFP mouse line (Strain 011391-UCD), the present study is the first to demonstrate the recruitment of excitatory interneurons into injured phrenic circuitry after a high cervical SCI. Diaphragm electromyography and anatomical analysis were used to confirm lesion-induced functional deficits and document extent of the lesion, respectively. Transneuronal tracing with pseudorabies virus (PRV) was used to identify interneurons within the phrenic circuitry. There was a robust increase in the number of PRV-labeled V2a interneurons ipsilateral to the C2 hemisection, demonstrating that significant numbers of these excitatory spinal interneurons were anatomically recruited into the phrenic motor pathway two weeks after injury, a time known to correspond with functional phrenic plasticity. Understanding this anatomical spinal plasticity and the neural substrates associated with functional compensation or recovery post-SCI in a controlled, experimental setting may help shed light onto possible cellular therapeutic candidates that can be targeted to enhance spontaneous recovery.
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Affiliation(s)
- Lyandysha V Zholudeva
- 1 Department of Neurobiology and Anatomy, College of Medicine, Drexel University , Philadelphia, Pennsylvania.,2 The Spinal Cord Research Center, College of Medicine, Drexel University , Philadelphia, Pennsylvania
| | - Jordyn S Karliner
- 1 Department of Neurobiology and Anatomy, College of Medicine, Drexel University , Philadelphia, Pennsylvania.,2 The Spinal Cord Research Center, College of Medicine, Drexel University , Philadelphia, Pennsylvania.,3 Department of Neuroscience, Ursinus College , Collegeville, Pennsylvania
| | - Kimberly J Dougherty
- 1 Department of Neurobiology and Anatomy, College of Medicine, Drexel University , Philadelphia, Pennsylvania.,2 The Spinal Cord Research Center, College of Medicine, Drexel University , Philadelphia, Pennsylvania
| | - Michael A Lane
- 1 Department of Neurobiology and Anatomy, College of Medicine, Drexel University , Philadelphia, Pennsylvania.,2 The Spinal Cord Research Center, College of Medicine, Drexel University , Philadelphia, Pennsylvania
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13
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Lee KZ, Chiang SC, Li YJ. Mild Acute Intermittent Hypoxia Improves Respiratory Function in Unanesthetized Rats With Midcervical Contusion. Neurorehabil Neural Repair 2016; 31:364-375. [DOI: 10.1177/1545968316680494] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Background. Mild intermittent hypoxia has been considered a potential approach to induce respiratory neuroplasticity. Objective. The purpose of the present study was to investigate whether mild acute intermittent hypoxia can improve breathing function in a clinically relevant spinal cord injury animal model. Methods. Adult male rats received laminectomy or unilateral contusion at the C3-C4 spinal cord using a MASCIS Impactor (height: 6.25 or 12.5 mm). At 4 weeks postinjury, the breathing patterns of unanesthetized rats were measured by whole body plethysmography before, during and after 10 episodes of 5 minutes of hypoxia (10% O2, 4% CO2, balance N2) with 5 minutes of normoxia intervals. Results. The results demonstrated that cervical contusion resulted in reduction in breathing capacity and number of phrenic motoneurons. Acute hypoxia induced significant increases in frequency and tidal volume in sham surgery and contused animals. In addition, there was a progressive decline in the magnitude of hypoxic ventilatory response during intermittent hypoxia. Further, the tidal volume was significantly enhanced in contused but not sham surgery rats at 15 and 30 minutes postintermittent hypoxia, suggesting intermittent hypoxia can bring about long-term facilitation of tidal volume following cervical spinal contusion. Conclusions. These results suggest that mild acute intermittent hypoxia can elicit differential forms of respiratory plasticity in sham surgery versus contused animals, and may be a promising neurorehabilitation approach to improve respiratory function after cervical spinal cord injury.
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Affiliation(s)
- Kun-Ze Lee
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
- Center for Neuroscience, National Sun Yat-sen University, Kaohsiung, Taiwan
- Institute of Medical Science and Technology, National Sun Yat-sen University, Kaohsiung, Taiwan
- Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University and Academia Sinica, Taiwan
- Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Shu-Chi Chiang
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Yu-Jie Li
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
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