1
|
Benevides ES, Thakre PP, Rana S, Sunshine MD, Jensen VN, Oweiss K, Fuller DD. Chemogenetic stimulation of phrenic motor output and diaphragm activity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.12.589188. [PMID: 38659846 PMCID: PMC11042184 DOI: 10.1101/2024.04.12.589188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Impaired diaphragm activation contributes to morbidity and mortality in many neurodegenerative diseases and neurologic injuries. We conducted experiments to determine if expression of an excitatory DREADD (designer receptors exclusively activation by designer drugs) in the mid-cervical spinal cord would enable respiratory-related activation of phrenic motoneurons to increase diaphragm activation. Wild type (C57/bl6) and ChAT-Cre mice received bilateral intraspinal (C4) injections of an adeno-associated virus (AAV) encoding the hM3D(Gq) excitatory DREADD. In wild type mice, this produced non-specific DREADD expression throughout the mid-cervical ventral horn. In ChAT-Cre mice, a Cre-dependent viral construct was used to drive DREADD expression in C4 ventral horn motoneurons, targeting the phrenic motoneuron pool. Diaphragm EMG was recorded during spontaneous breathing at 6-8 weeks post-AAV delivery. The selective DREADD ligand JHU37160 (J60) caused a bilateral, sustained (>1 hr) increase in inspiratory EMG bursting in both groups; the relative increase was greater in ChAT-Cre mice. Additional experiments in a ChAT-Cre rat model were conducted to determine if spinal DREADD activation could increase inspiratory tidal volume (VT) during spontaneous breathing without anesthesia. Three to four months after intraspinal (C4) injection of AAV driving Cre-dependent hM3D(Gq) expression, intravenous J60 resulted in a sustained (>30 min) increase in VT assessed using whole-body plethysmography. Subsequently, direct nerve recordings confirmed that J60 evoked a >50% increase in inspiratory phrenic output. The data show that mid-cervical spinal DREADD expression targeting the phrenic motoneuron pool enables ligand-induced, sustained increases in the neural drive to the diaphragm. Further development of this technology may enable application to clinical conditions associated with impaired diaphragm activation and hypoventilation.
Collapse
Affiliation(s)
- Ethan S Benevides
- Department of Physical Therapy, University of Florida, Gainesville, FL, 32601
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, 32601
| | - Prajwal P Thakre
- Department of Physical Therapy, University of Florida, Gainesville, FL, 32601
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, 32601
- McKnight Brain Institute, University of Florida, Gainesville, FL, 32601
| | - Sabhya Rana
- Department of Physical Therapy, University of Florida, Gainesville, FL, 32601
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, 32601
- McKnight Brain Institute, University of Florida, Gainesville, FL, 32601
| | - Michael D Sunshine
- Department of Physical Therapy, University of Florida, Gainesville, FL, 32601
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, 32601
- McKnight Brain Institute, University of Florida, Gainesville, FL, 32601
| | - Victoria N Jensen
- Department of Physical Therapy, University of Florida, Gainesville, FL, 32601
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, 32601
- McKnight Brain Institute, University of Florida, Gainesville, FL, 32601
| | - Karim Oweiss
- McKnight Brain Institute, University of Florida, Gainesville, FL, 32601
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL, 32601
| | - David D Fuller
- Department of Physical Therapy, University of Florida, Gainesville, FL, 32601
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, 32601
- McKnight Brain Institute, University of Florida, Gainesville, FL, 32601
| |
Collapse
|
2
|
Dominguez-Bajo A, Clotman F. Potential Roles of Specific Subclasses of Premotor Interneurons in Spinal Cord Function Recovery after Traumatic Spinal Cord Injury in Adults. Cells 2024; 13:652. [PMID: 38667267 PMCID: PMC11048910 DOI: 10.3390/cells13080652] [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: 03/01/2024] [Revised: 04/04/2024] [Accepted: 04/05/2024] [Indexed: 04/28/2024] Open
Abstract
The differential expression of transcription factors during embryonic development has been selected as the main feature to define the specific subclasses of spinal interneurons. However, recent studies based on single-cell RNA sequencing and transcriptomic experiments suggest that this approach might not be appropriate in the adult spinal cord, where interneurons show overlapping expression profiles, especially in the ventral region. This constitutes a major challenge for the identification and direct targeting of specific populations that could be involved in locomotor recovery after a traumatic spinal cord injury in adults. Current experimental therapies, including electrical stimulation, training, pharmacological treatments, or cell implantation, that have resulted in improvements in locomotor behavior rely on the modulation of the activity and connectivity of interneurons located in the surroundings of the lesion core for the formation of detour circuits. However, very few publications clarify the specific identity of these cells. In this work, we review the studies where premotor interneurons were able to create new intraspinal circuits after different kinds of traumatic spinal cord injury, highlighting the difficulties encountered by researchers, to classify these populations.
Collapse
Affiliation(s)
- Ana Dominguez-Bajo
- Université catholique de Louvain, Louvain Institute of Biomolecular Science and Technology (LIBST), Animal Molecular and Cellular Biology Group (AMCB), Place Croix du Sud 4–5, 1348 Louvain la Neuve, Belgium
| | - Frédéric Clotman
- Université catholique de Louvain, Louvain Institute of Biomolecular Science and Technology (LIBST), Animal Molecular and Cellular Biology Group (AMCB), Place Croix du Sud 4–5, 1348 Louvain la Neuve, Belgium
| |
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
Fogarty MJ, Zhan WZ, Mantilla CB, Sieck GC. Cervical spinal cord hemisection impacts sigh and the respiratory reset in male rats. Physiol Rep 2024; 12:e15973. [PMID: 38467570 DOI: 10.14814/phy2.15973] [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: 10/05/2023] [Revised: 02/28/2024] [Accepted: 02/29/2024] [Indexed: 03/13/2024] Open
Abstract
Cervical spinal cord injury impacts ventilatory and non-ventilatory functions of the diaphragm muscle (DIAm) and contributes to clinical morbidity and mortality in the afflicted population. Periodically, integrated brainstem neural circuit activity drives the DIAm to generate a markedly augmented effort or sigh-which plays an important role in preventing atelectasis and thus maintaining lung function. Across species, the general pattern of DIAm efforts during a normal sigh is variable in amplitude and the extent of post-sigh "apnea" (i.e., the post-sigh inter-breath interval). This post-sigh inter-breath interval acts as a respiratory reset, following the interruption of regular respiratory rhythm by sigh. We examined the impact of upper cervical (C2 ) spinal cord hemisection (C2 SH) on the transdiaphragmatic pressure (Pdi ) generated during sighs and the post-sigh respiratory reset in rats. Sighs were identified in Pdi traces by their characteristic biphasic pattern. We found that C2 SH results in a reduction of Pdi during both eupnea and sighs, and a decrease in the immediate post-sigh breath interval. These results are consistent with partial removal of descending excitatory synaptic inputs to phrenic motor neurons that results from C2 SH. Following cervical spinal cord injury, a reduction in the amplitude of Pdi during sighs may compromise the maintenance of normal lung function.
Collapse
Affiliation(s)
- Matthew J Fogarty
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Wen-Zhi Zhan
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Carlos B Mantilla
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Gary C Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| |
Collapse
|
5
|
Xie Y, Zhang L, Guo S, Peng R, Gong H, Yang M. Changes in respiratory structure and function after traumatic cervical spinal cord injury: observations from spinal cord and brain. Front Neurol 2023; 14:1251833. [PMID: 37869136 PMCID: PMC10587692 DOI: 10.3389/fneur.2023.1251833] [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: 07/02/2023] [Accepted: 09/18/2023] [Indexed: 10/24/2023] Open
Abstract
Respiratory difficulties and mortality following severe cervical spinal cord injury (CSCI) result primarily from malfunctions of respiratory pathways and the paralyzed diaphragm. Nonetheless, individuals with CSCI can experience partial recovery of respiratory function through respiratory neuroplasticity. For decades, researchers have revealed the potential mechanism of respiratory nerve plasticity after CSCI, and have made progress in tissue healing and functional recovery. While most existing studies on respiratory plasticity after spinal cord injuries have focused on the cervical spinal cord, there is a paucity of research on respiratory-related brain structures following such injuries. Given the interconnectedness of the spinal cord and the brain, traumatic changes to the former can also impact the latter. Consequently, are there other potential therapeutic targets to consider? This review introduces the anatomy and physiology of typical respiratory centers, explores alterations in respiratory function following spinal cord injuries, and delves into the structural foundations of modified respiratory function in patients with CSCI. Additionally, we propose that magnetic resonance neuroimaging holds promise in the study of respiratory function post-CSCI. By studying respiratory plasticity in the brain and spinal cord after CSCI, we hope to guide future clinical work.
Collapse
Affiliation(s)
- Yongqi Xie
- School of Rehabilitation Medicine, Capital Medical University, Beijing, China
| | - Liang Zhang
- School of Rehabilitation Medicine, Capital Medical University, Beijing, China
| | - Shuang Guo
- School of Rehabilitation Medicine, Capital Medical University, Beijing, China
- Department of Rehabilitation, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Run Peng
- School of Rehabilitation Medicine, Capital Medical University, Beijing, China
| | - Huiming Gong
- School of Rehabilitation Medicine, Capital Medical University, Beijing, China
- Department of Spinal and Neural Functional Reconstruction, China Rehabilitation Research Center, Beijing, China
| | - Mingliang Yang
- School of Rehabilitation Medicine, Capital Medical University, Beijing, China
- Department of Spinal and Neural Functional Reconstruction, China Rehabilitation Research Center, Beijing, China
- Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
| |
Collapse
|
6
|
Baltin M, Smirnova V, Khamatnurova R, Sabirova D, Samigullin B, Sachenkov O, Baltina T. Functional State of the Motor Centers of the Lumbar Spine after Contusion (Th8-Th9) with Application of Methylprednisolone-Copolymer at the Site of Injury. Biomedicines 2023; 11:2026. [PMID: 37509665 PMCID: PMC10377350 DOI: 10.3390/biomedicines11072026] [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: 05/11/2023] [Revised: 07/06/2023] [Accepted: 07/10/2023] [Indexed: 07/30/2023] Open
Abstract
Spinal cord injuries must be treated as soon as possible. Studies of NASCIS protocols have questioned the use of methylprednisolone therapy. This study aimed to evaluate the effect of local delivery of methylprednisolone succinate in combination with a tri-block copolymer in rats with spinal cord injury. The experiments were conducted in accordance with the bioethical guidelines. We evaluated the state of the motor centers below the level of injury by assessing the amplitude of evoked motor responses in the hind limb muscles of rats during epidural stimulation. Kinematic analysis was performed to examine the stepping cycle in each rat. Trajectories of foot movements were plotted to determine the range of limb motion, maximum foot lift height, and lateral deviation of the foot in rats on the 21st day after spinal cord injury. We have shown that the local application of methylprednisolone succinate in combination with block copolymer leads to recovery of center excitability by 21 days after injury. In rats, they recovered weight-supported locomotion, directional control of walking, and balance. The proposed assessment method provides valuable information on gait disturbances following injury and can be utilized to evaluate the quality of therapeutic interventions.
Collapse
Affiliation(s)
- Maxim Baltin
- Research Laboratory "Mechanobiology", Institute of Fundamental Medicine and Biology, Kazan Federal University, 420015 Kazan, Russia
- Research Institute of Sports Reserve Training Technologies, Volga State University of Physical Culture, Sports and Tourism, Universiade Village, 35, 420010 Kazan, Russia
| | - Victoriya Smirnova
- N.I. Lobachevsky Institute of Mathematics and Mechanics, Kazan Federal University, 420008 Kazan, Russia
| | - Regina Khamatnurova
- Interdisciplinary Neuroscience Faculty, Goethe-Universität Frankfurt am Main, 60323 Frankfurt am Main, Germany
| | - Diana Sabirova
- N.I. Lobachevsky Institute of Mathematics and Mechanics, Kazan Federal University, 420008 Kazan, Russia
- Department of Human and Animal Physiology, Institute of Fundamental Medicine and Biology, Kazan Federal University, 76 K. Marx St., 420015 Kazan, Russia
| | - Bulat Samigullin
- Research Laboratory "Mechanobiology", Institute of Fundamental Medicine and Biology, Kazan Federal University, 420015 Kazan, Russia
- NeuroStart Medical Center, 420049 Kazan, Russia
| | - Oskar Sachenkov
- N.I. Lobachevsky Institute of Mathematics and Mechanics, Kazan Federal University, 420008 Kazan, Russia
- Department Machines Science and Engineering Graphics, Tupolev Kazan National Research Technical University, 420111 Kazan, Russia
| | - Tatyana Baltina
- Research Laboratory "Mechanobiology", Institute of Fundamental Medicine and Biology, Kazan Federal University, 420015 Kazan, Russia
- Department of Human and Animal Physiology, Institute of Fundamental Medicine and Biology, Kazan Federal University, 76 K. Marx St., 420015 Kazan, Russia
| |
Collapse
|
7
|
Fogarty MJ, Zhan WZ, Simmon VF, Vanderklish PW, Sarraf ST, Sieck GC. Novel regenerative drug, SPG302 promotes functional recovery of diaphragm muscle activity after cervical spinal cord injury. J Physiol 2023; 601:2513-2532. [PMID: 36815402 PMCID: PMC10404468 DOI: 10.1113/jp284004] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 02/17/2023] [Indexed: 02/24/2023] Open
Abstract
Spinal cord hemisection at C2 (C2 SH), sparing the dorsal column is widely used to investigate the effects of reduced phrenic motor neuron (PhMN) activation on diaphragm muscle (DIAm) function, with reduced DIAm activity on the injured side during eupnoea. Following C2 SH, recovery of DIAm EMG activity may occur spontaneously over subsequent days/weeks. Various strategies have been effective at improving the incidence and magnitude of DIAm recovery during eupnoea, but little is known about the effects of C2 SH on transdiaphragmatic pressure (Pdi ) during other ventilatory and non-ventilatory behaviours. We employ SPG302, a novel type of pegylated benzothiazole derivative, to assess whether enhancing synaptogenesis (i.e., enhancing spared local connections) will improve the incidence and the magnitude of recovery of DIAm EMG activity and Pdi function 14 days post-C2 SH. In anaesthetised Sprague-Dawley rats, DIAm EMG and Pdi were assessed during eupnoea, hypoxia/hypercapnia and airway occlusion prior to surgery (C2 SH or sham), immediately post-surgery and at 14 days post-surgery. In C2 SH rats, 14 days of DMSO (vehicle) or SPG302 treatments (i.p. injection) occurred. At the terminal experiment, maximum Pdi was evoked by bilateral phrenic nerve stimulation. We show that significant EMG and Pdi deficits are apparent in C2 SH compared with sham rats immediately after surgery. In C2 SH rats treated with SPG302, recovery of eupneic, hypoxia/hypercapnia and occlusion DIAm EMG was enhanced compared with vehicle rats after 14 days. Treatment with SPG302 also ameliorated Pdi deficits following C2 SH. In summary, SPG302 is an exciting new therapy to explore for use in spinal cord injuries. KEY POINTS: Despite advances in our understanding of the effects of cervical hemisection (C2 SH) on diaphragm muscle (DIAm) EMG activity, very little is understood about the impact of C2 SH on the gamut of ventilatory and non-ventilatory transdiaphragmatic pressures (Pdi ). Recovery of DIAm activity following C2 SH is improved using a variety of approaches, but very few pharmaceuticals have been shown to be effective. One way of improving DIAm recovery is to enhance the amount of latent local spared connections onto phrenic motor neurons. A novel pegylated benzothiazole derivative enhances synaptogenesis in a variety of neurodegenerative conditions. Here, using a novel therapeutic SPG302, we show that 14 days of treatment with SPG302 ameliorated DIAm EMG and Pdi deficits compared with vehicle controls. Our results show that SPG302 is a compound with very promising potential for use in improving functional outcomes post-spinal cord injury.
Collapse
Affiliation(s)
- Matthew J. Fogarty
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Wen-Zhi Zhan
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Vincent F. Simmon
- Spinogenix Inc, 4225 Executive Square, Suite 600 La Jolla, California, USA
| | | | - Stella T. Sarraf
- Spinogenix Inc, 4225 Executive Square, Suite 600 La Jolla, California, USA
| | - Gary C. Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| |
Collapse
|
8
|
Lee KZ. Neuropathology of distinct diaphragm areas following mid-cervical spinal cord contusion in the rat. Spine J 2022; 22:1726-1741. [PMID: 35680014 DOI: 10.1016/j.spinee.2022.05.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 05/17/2022] [Accepted: 05/26/2022] [Indexed: 02/03/2023]
Abstract
BACKGROUND The diaphragm is innervated by phrenic motoneurons distributed from the third to fifth cervical spinal cord. The rostral to caudal phrenic motoneuron pool segmentally innervates the ventral, medial, and dorsal diaphragm. PURPOSE The present study was designed to investigate the physiological and transcriptomic mechanism of neuropathology of distinct diaphragm areas following mid-cervical spinal cord injury. STUDY DESIGN In vivo animal study. METHODS Electromyograms and transcriptome of the ventral, medial, and dorsal diaphragm were examined in rats that received cervical laminectomy or mid-cervical spinal cord contusion in the acute (ie, 1-3 days) or subchronic (ie, ∼14 days) injury stages. RESULTS Mid-cervical spinal cord contusion significantly attenuated the inspiratory bursting amplitude of the dorsal diaphragm but not the ventral or medial diaphragm. Moreover, the discharge onset of the dorsal diaphragm was significantly delayed compared with that of the ventral and medial diaphragm in contused rats. Transcriptomic analysis revealed a robust change in gene expression in the ventral diaphragm compared with that in the dorsal diaphragm. Specifically, enrichment analysis of differentially expressed genes demonstrated that the cell cycle and immune response were significantly upregulated, whereas several metabolic pathways were downregulated, in the ventral diaphragm of acutely contused rats. However, no significant Kyoto Encyclopedia of Genes and Genomes pathway was altered in the dorsal diaphragm. CONCLUSIONS These results suggest that mid-cervical spinal cord injury has different impacts on the physiological and transcriptomic responses of distinct diaphragm areas. CLINICAL SIGNIFICANCE Future therapeutic strategies can consider applying different therapies to distinct diaphragm areas following cervical spinal cord injury. Additionally, confirmation of activities across different diaphragm areas may provide a critical reference for the placement of diaphragmatic pacing electrodes.
Collapse
Affiliation(s)
- 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.
| |
Collapse
|
9
|
Brown AD, Fogarty MJ, Davis LA, Dasgupta D, Mantilla CB, Sieck GC. Mitochondrial adaptations to inactivity in diaphragm muscle fibers. J Appl Physiol (1985) 2022; 133:191-204. [PMID: 35678745 PMCID: PMC9291409 DOI: 10.1152/japplphysiol.00090.2022] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Type I and IIa diaphragm muscle (DIAm) fibers comprise slow and fast fatigue-resistant motor units that are recruited to accomplish breathing and thus have a high duty cycle. In contrast, type IIx/IIb fibers comprise more fatigable fast motor units that are infrequently recruited for airway protective and straining behaviors. We hypothesize that mitochondrial structure and function in type I and IIa DIAm fibers adapt in response to inactivity imposed by spinal cord hemisection at C2 (C2SH). At 14 days after C2SH, the effect of inactivity on mitochondrial structure and function was assessed in DIAm fibers. Mitochondria in DIAm fibers were labeled using MitoTracker Green (Thermo Fisher Scientific), imaged in three-dimensions (3-D) by fluorescence confocal microscopy, and images were analyzed for mitochondrial volume density (MVD) and complexity. DIAm homogenate from either side was assessed for PGC1α, Parkin, MFN2, and DRP1 using Western blot. In alternate serial sections of the same DIAm fibers, the maximum velocity of the succinate dehydrogenase reaction (SDHmax) was determined using a quantitative histochemical technique. In all groups and both sides of the DIAm, type I and IIa DIAm fibers exhibited higher MVD, with more filamentous mitochondria and had higher SDHmax normalized to both fiber volume and mitochondrial volume compared with type IIx/IIb Diam fibers. In the inactive right side of the DIAm, mitochondria became fragmented and MVD decreased in all fiber types compared with the intact side and sham controls, consistent with the observed reduction in PGC1α and increased Parkin and DRP1 expression. In the inactive side of the DIAm, the reduction in SDHmax was found only for type I and IIa fibers. These results show that there are intrinsic fiber-type-dependent differences in the structure and function of mitochondria in DIAm fibers. Following C2SH-induced inactivity, mitochondrial structure (MVD and fragmentation) and function (SDHmax) were altered, indicating that inactivity influences all DIAm fiber types, but inactivity disproportionately affected SDHmax in the more intrinsically active type I and IIa fibers.NEW & NOTEWORTHY Two weeks of diaphragm (DIAm) inactivity imposed by C2SH caused reduced mitochondrial volume density, mitochondrial fragmentation, and a concomitant reduction of SDHmax in type I and IIa DIAm fibers on the lesioned side. Type I and IIa DIAm fibers were far more sensitive to inactivation than type IIx/IIb fibers, which exhibited little pathology. Our results indicate that mitochondria in DIAm fibers are plastic in response to varying levels of activity.
Collapse
|
10
|
Benevides ES, Sunshine MD, Rana S, Fuller DD. Optogenetic activation of the diaphragm. Sci Rep 2022; 12:6503. [PMID: 35444167 PMCID: PMC9021282 DOI: 10.1038/s41598-022-10240-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 04/04/2022] [Indexed: 11/10/2022] Open
Abstract
Impaired diaphragm activation is common in many neuromuscular diseases. We hypothesized that expressing photoreceptors in diaphragm myofibers would enable light stimulation to evoke functional diaphragm activity, similar to endogenous bursts. In a mouse model, adeno-associated virus (AAV) encoding channelrhodopsin-2 (AAV9-CAG-ChR2-mVenus, 6.12 × 1011 vg dose) was delivered to the diaphragm using a minimally invasive method of microinjection to the intrapleural space. At 8-18 weeks following AAV injection, mice were anesthetized and studied during spontaneous breathing. We first showed that diaphragm electromyographic (EMG) potentials could be evoked with brief presentations of light, using a 473 nm high intensity LED. Evoked potential amplitude increased with intensity or duration of the light pulse. We next showed that in a paralyzed diaphragm, trains of light pulses evoked diaphragm EMG activity which resembled endogenous bursting, and this was sufficient to generate respiratory airflow. Light-evoked diaphragm EMG bursts showed no diminution after up to one hour of stimulation. Histological evaluation confirmed transgene expression in diaphragm myofibers. We conclude that intrapleural delivery of AAV9 can drive expression of ChR2 in the diaphragm and subsequent photostimulation can evoke graded compound diaphragm EMG activity similar to endogenous inspiratory bursting.
Collapse
Affiliation(s)
- Ethan S Benevides
- Rehabilitation Science PhD Program, University of Florida, Gainesville, Florida, USA.,Department of Physical Therapy, University of Florida, Gainesville, Florida, USA.,Breathing Research and Therapeutics Center, University of Florida, Gainesville, Florida, USA.,McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - Michael D Sunshine
- Department of Physical Therapy, University of Florida, Gainesville, Florida, USA.,Breathing Research and Therapeutics Center, University of Florida, Gainesville, Florida, USA.,McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - Sabhya Rana
- Department of Physical Therapy, University of Florida, Gainesville, Florida, USA.,Breathing Research and Therapeutics Center, University of Florida, Gainesville, Florida, USA.,McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - David D Fuller
- Department of Physical Therapy, University of Florida, Gainesville, Florida, USA. .,Breathing Research and Therapeutics Center, University of Florida, Gainesville, Florida, USA. .,McKnight Brain Institute, University of Florida, Gainesville, Florida, USA.
| |
Collapse
|
11
|
Effects of Chronic High-Frequency rTMS Protocol on Respiratory Neuroplasticity Following C2 Spinal Cord Hemisection in Rats. BIOLOGY 2022; 11:biology11030473. [PMID: 35336846 PMCID: PMC8945729 DOI: 10.3390/biology11030473] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/14/2022] [Accepted: 03/16/2022] [Indexed: 11/22/2022]
Abstract
Simple Summary High spinal cord injuries (SCIs) are known to lead to permanent diaphragmatic paralysis, and to induce deleterious post-traumatic inflammatory processes following cervical spinal cord injury. We used a noninvasive therapeutic tool (repetitive transcranial magnetic stimulation (rTMS)), to harness plasticity in spared descending respiratory circuit and reduce the inflammatory processes. Briefly, the results obtained in this present study suggest that chronic high-frequency rTMS can ameliorate respiratory dysfunction and elicit neuronal plasticity with a reduction in deleterious post-traumatic inflammatory processes in the cervical spinal cord post-SCI. Thus, this therapeutic tool could be adopted and/or combined with other therapeutic interventions in order to further enhance beneficial outcomes. Abstract High spinal cord injuries (SCIs) lead to permanent diaphragmatic paralysis. The search for therapeutics to induce functional motor recovery is essential. One promising noninvasive therapeutic tool that could harness plasticity in a spared descending respiratory circuit is repetitive transcranial magnetic stimulation (rTMS). Here, we tested the effect of chronic high-frequency (10 Hz) rTMS above the cortical areas in C2 hemisected rats when applied for 7 days, 1 month, or 2 months. An increase in intact hemidiaphragm electromyogram (EMG) activity and excitability (diaphragm motor evoked potentials) was observed after 1 month of rTMS application. Interestingly, despite no real functional effects of rTMS treatment on the injured hemidiaphragm activity during eupnea, 2 months of rTMS treatment strengthened the existing crossed phrenic pathways, allowing the injured hemidiaphragm to increase its activity during the respiratory challenge (i.e., asphyxia). This effect could be explained by a strengthening of respiratory descending fibers in the ventrolateral funiculi (an increase in GAP-43 positive fibers), sustained by a reduction in inflammation in the C1–C3 spinal cord (reduction in CD68 and Iba1 labeling), and acceleration of intracellular plasticity processes in phrenic motoneurons after chronic rTMS treatment. These results suggest that chronic high-frequency rTMS can ameliorate respiratory dysfunction and elicit neuronal plasticity with a reduction in deleterious post-traumatic inflammatory processes in the cervical spinal cord post-SCI. Thus, this therapeutic tool could be adopted and/or combined with other therapeutic interventions in order to further enhance beneficial outcomes.
Collapse
|
12
|
Le Ray D, Guayasamin M. How Does the Central Nervous System for Posture and Locomotion Cope With Damage-Induced Neural Asymmetry? Front Syst Neurosci 2022; 16:828532. [PMID: 35308565 PMCID: PMC8927091 DOI: 10.3389/fnsys.2022.828532] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 02/07/2022] [Indexed: 12/28/2022] Open
Abstract
In most vertebrates, posture and locomotion are achieved by a biomechanical apparatus whose effectors are symmetrically positioned around the main body axis. Logically, motor commands to these effectors are intrinsically adapted to such anatomical symmetry, and the underlying sensory-motor neural networks are correspondingly arranged during central nervous system (CNS) development. However, many developmental and/or life accidents may alter such neural organization and acutely generate asymmetries in motor operation that are often at least partially compensated for over time. First, we briefly present the basic sensory-motor organization of posturo-locomotor networks in vertebrates. Next, we review some aspects of neural plasticity that is implemented in response to unilateral central injury or asymmetrical sensory deprivation in order to substantially restore symmetry in the control of posturo-locomotor functions. Data are finally discussed in the context of CNS structure-function relationship.
Collapse
|
13
|
Malone IG, Kelly MN, Nosacka RL, Nash MA, Yue S, Xue W, Otto KJ, Dale EA. Closed-Loop, Cervical, Epidural Stimulation Elicits Respiratory Neuroplasticity after Spinal Cord Injury in Freely Behaving Rats. eNeuro 2022; 9:ENEURO.0426-21.2021. [PMID: 35058311 PMCID: PMC8856702 DOI: 10.1523/eneuro.0426-21.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 12/08/2021] [Accepted: 12/24/2021] [Indexed: 11/28/2022] Open
Abstract
Over half of all spinal cord injuries (SCIs) are cervical, which can lead to paralysis and respiratory compromise, causing significant morbidity and mortality. Effective treatments to restore breathing after severe upper cervical injury are lacking; thus, it is imperative to develop therapies to address this. Epidural stimulation has successfully restored motor function after SCI for stepping, standing, reaching, grasping, and postural control. We hypothesized that closed-loop stimulation triggered via healthy hemidiaphragm EMG activity has the potential to elicit functional neuroplasticity in spinal respiratory pathways after cervical SCI (cSCI). To test this, we delivered closed-loop, electrical, epidural stimulation (CLES) at the level of the phrenic motor nucleus (C4) for 3 d after C2 hemisection (C2HS) in freely behaving rats. A 2 × 2 Latin Square experimental design incorporated two treatments, C2HS injury and CLES therapy resulting in four groups of adult, female Sprague Dawley rats: C2HS + CLES (n = 8), C2HS (n = 6), intact + CLES (n = 6), intact (n = 6). In stimulated groups, CLES was delivered for 12-20 h/d for 3 d. After C2HS, 3 d of CLES robustly facilitated the slope of stimulus-response curves of ipsilesional spinal motor evoked potentials (sMEPs) versus nonstimulated controls. To our knowledge, this is the first demonstration of CLES eliciting respiratory neuroplasticity after C2HS in freely behaving animals. These findings suggest CLES as a promising future therapy to address respiratory deficiency associated with cSCI.
Collapse
Affiliation(s)
- Ian G Malone
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL 32611
| | - Mia N Kelly
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL 32611
- Department of Physical Therapy, University of Florida, Gainesville, FL 32611
| | - Rachel L Nosacka
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL 32611
| | - Marissa A Nash
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL 32611
| | - Sijia Yue
- Department of Biostatistics, University of Florida, Gainesville, FL 32611
| | - Wei Xue
- Department of Biostatistics, University of Florida, Gainesville, FL 32611
| | - Kevin J Otto
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL 32611
- McKnight Brain Institute, University of Florida, Gainesville, FL 32611
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611
- Department of Neurology, University of Florida, Gainesville, FL 32611
- Department of Neuroscience, University of Florida, Gainesville, FL 32611
| | - Erica A Dale
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL 32611
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL 32611
- McKnight Brain Institute, University of Florida, Gainesville, FL 32611
| |
Collapse
|
14
|
Allen LL, Nichols NL, Asa ZA, Emery AT, Ciesla MC, Santiago JV, Holland AE, Mitchell GS, Gonzalez-Rothi EJ. Phrenic motor neuron survival below cervical spinal cord hemisection. Exp Neurol 2021; 346:113832. [PMID: 34363808 PMCID: PMC9065093 DOI: 10.1016/j.expneurol.2021.113832] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 07/31/2021] [Accepted: 08/02/2021] [Indexed: 02/04/2023]
Abstract
Cervical spinal cord injury (cSCI) severs bulbospinal projections to respiratory motor neurons, paralyzing respiratory muscles below the injury. C2 spinal hemisection (C2Hx) is a model of cSCI often used to study spontaneous and induced plasticity and breathing recovery post-injury. One key assumption is that C2Hx dennervates motor neurons below the injury, but does not affect their survival. However, a recent study reported substantial bilateral motor neuron death caudal to C2Hx. Since phrenic motor neuron (PMN) death following C2Hx would have profound implications for therapeutic strategies designed to target spared neural circuits, we tested the hypothesis that C2Hx minimally impacts PMN survival. Using improved retrograde tracing methods, we observed no loss of PMNs at 2- or 8-weeks post-C2Hx. We also observed no injury-related differences in ChAT or NeuN immunolabeling within labelled PMNs. Although we found no evidence of PMN loss following C2Hx, we cannot rule out neuronal loss in other motor pools. These findings address an essential prerequisite for studies that utilize C2Hx as a model to explore strategies for inducing plasticity and/or regeneration within the phrenic motor system, as they provide important insights into the viability of phrenic motor neurons as therapeutic targets after high cervical injury.
Collapse
Affiliation(s)
- Latoya L Allen
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Nicole L Nichols
- Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, USA
| | - Zachary A Asa
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | | | - Marissa C Ciesla
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Juliet V Santiago
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Ashley E Holland
- 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
| | - Elisa J Gonzalez-Rothi
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA.
| |
Collapse
|
15
|
Yin Y, Yang X, Tian Y, Zhang Y, Zhang P, Jia Y, Yao Y, Du X, Li T, Li X. Synchronized and integrated prehospital treatment for acute cervical spinal cord injury. Am J Transl Res 2021; 13:7008-7014. [PMID: 34306456 PMCID: PMC8290651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 02/21/2021] [Indexed: 06/13/2023]
Abstract
OBJECTIVE To explore the effect of synchronized and integrated prehospital treatment strategies for on-site first aid, rescue transport and prehospital first aid in patients with acute cervical spinal cord injury. METHODS A prospective non-randomized controlled study was designed to include patients with acute cervical spinal cord injury. A total of 50 patients were included in a Control group (before the implementation of synchronized and integrated prehospital treatment), and 50 patients were included in an Observation Group (after the implementation of synchronized and integrated prehospital treatment). We compared the timeliness of prehospital treatment, the proportion of patients received methylprednisolone treatment within 3 h after injury, the changes in Japanese Orthopaedic Association (JOA) score during transport, the incidence of adverse events, the clinical outcomes, the number of prehospital deaths, the case number of paralysis and the recovery of postoperative neural function between the two groups. RESULTS Compared with the Control group, the Observation group showed significantly shorter time from injury to admission, from injury to receiving methylprednisolone pulse therapy, as well as from injury to receiving dehydrating agents and diuretics (all P<0.001). The proportion of patients received methylprednisolone treatment within 3 h after injury was significantly higher in the Observation group than that in the Control group (P<0.05). There was no significant change in the JOA score in the Observation group before and after the transport, while the score was significantly lower in the Control group after the transport (P<0.001). The JOA score was higher in the Observation group than that in the Control group at admission (P<0.001). The Observation group also showed decreased incidences of adverse events, mortality, and paralysis rate (all P<0.05) as well as better recovery of postoperative neural function (P<0.001) when compared with the Control group. CONCLUSION Synchronized and integrated prehospital treatment has a significant effect in patients with acute cervical spinal cord injury through shortening the admission time, reducing the risk of adverse events, and improving the rescue effect and the prognosis of neural function.
Collapse
Affiliation(s)
- Yanlin Yin
- Department of Orthopedics, The First Affiliated Hospital of Hebei North UniversityZhangjiakou, Hebei Province, China
| | - Xinming Yang
- Department of Orthopedics, The First Affiliated Hospital of Hebei North UniversityZhangjiakou, Hebei Province, China
| | - Ye Tian
- Department of Orthopedics, The First Affiliated Hospital of Hebei North UniversityZhangjiakou, Hebei Province, China
| | - Ying Zhang
- Department of Orthopedics, The First Affiliated Hospital of Hebei North UniversityZhangjiakou, Hebei Province, China
| | - Peinan Zhang
- Department of Orthopedics, The First Affiliated Hospital of Hebei North UniversityZhangjiakou, Hebei Province, China
| | - Yongli Jia
- Department of Orthopedics, The First Affiliated Hospital of Hebei North UniversityZhangjiakou, Hebei Province, China
| | - Yao Yao
- Department of Orthopedics, The First Affiliated Hospital of Hebei North UniversityZhangjiakou, Hebei Province, China
| | - Xiuyu Du
- Department of Trauma, The First Affiliated Hospital of Hebei North UniversityZhangjiakou, Hebei Province, China
| | - Tianmin Li
- Department of General Practice, The First Affiliated Hospital of Hebei North UniversityZhangjiakou, Hebei Province, China
| | - Xiaodong Li
- Department of Imaging, The First Affiliated Hospital of Hebei North UniversityZhangjiakou, Hebei Province, China
| |
Collapse
|
16
|
Zhang P, Yang X, Yin Y, Zhang Z, Yao Y. Effects of multidisciplinary model of damage control on acute cervical spinal cord injury in winter Olympic sports. Am J Transl Res 2021; 13:5051-5058. [PMID: 34150091 PMCID: PMC8205732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 02/02/2021] [Indexed: 06/12/2023]
Abstract
PURPOSE To investigate the feasibility of multidisciplinary model of damage control (MMDC) in patients with acute cervical spinal cord injury (ACSCI) in winter Olympic sports. METHODS A total of 110 patients with ACSCI who participated in winter Olympic sports were selected as the study subjects, and were divided into the study group (SG, n=60, MMDC) and the control group (CG, n=50, conventional intervention) according to the intervention mode. The clinical effects of intervention, changes in neurological function and muscle tone before and after intervention, the changes in motor function and activity of daily living during intervention, and patient satisfaction towards intervention were compared between the two groups. RESULTS The effective rate of intervention in the SG was 98.33%, higher than 88.00% in the CG (P < 0.05), and the percentage of patients with Grade E injuries in the SG after intervention was 30.00%, significantly higher than 12.00% in the CG (P < 0.05). The scores of all dimensions of Ashworth scale in the SG were lower than those in the CG (P < 0.05). The patients in the SG exhibited higher FMA scale and modified Barthel index (MBI) scores than the CG from 1 to 6 months of intervention (P < 0.05). CONCLUSION MMDC showed better efficacy, the patients' neurological function, muscle tone and motor function could be better restored, and patients' abilities of daily activities were improved after intervention.
Collapse
Affiliation(s)
- Peinan Zhang
- The First Department of Orthopedics, The First Affiliated Hospital of Hebei North UniversityZhangjiakou 075000, Hebei Province, China
| | - Xinming Yang
- The First Department of Orthopedics, The First Affiliated Hospital of Hebei North UniversityZhangjiakou 075000, Hebei Province, China
| | - Yanlin Yin
- The First Department of Orthopedics, The First Affiliated Hospital of Hebei North UniversityZhangjiakou 075000, Hebei Province, China
| | - Zhenliang Zhang
- Department of Emergency Surgery, The First Affiliated Hospital of Hebei North UniversityZhangjiakou 075000, Hebei Province, China
| | - Yao Yao
- The First Department of Orthopedics, The First Affiliated Hospital of Hebei North UniversityZhangjiakou 075000, Hebei Province, China
| |
Collapse
|
17
|
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.
Collapse
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.
| |
Collapse
|
18
|
Zholudeva LV, Abraira VE, Satkunendrarajah K, McDevitt TC, Goulding MD, Magnuson DSK, Lane MA. Spinal Interneurons as Gatekeepers to Neuroplasticity after Injury or Disease. J Neurosci 2021; 41:845-854. [PMID: 33472820 PMCID: PMC7880285 DOI: 10.1523/jneurosci.1654-20.2020] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 12/15/2020] [Accepted: 12/17/2020] [Indexed: 12/15/2022] Open
Abstract
Spinal interneurons are important facilitators and modulators of motor, sensory, and autonomic functions in the intact CNS. This heterogeneous population of neurons is now widely appreciated to be a key component of plasticity and recovery. This review highlights our current understanding of spinal interneuron heterogeneity, their contribution to control and modulation of motor and sensory functions, and how this role might change after traumatic spinal cord injury. We also offer a perspective for how treatments can optimize the contribution of interneurons to functional improvement.
Collapse
Affiliation(s)
| | - Victoria E Abraira
- Department of Cell Biology & Neuroscience, Rutgers University, The State University of New Jersey, New Jersey, 08854
| | - Kajana Satkunendrarajah
- Departments of Neurosurgery and Physiology, Medical College of Wisconsin, Wisconsin, 53226
- Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, 53295
| | - Todd C McDevitt
- Gladstone Institutes, San Francisco, California, 94158
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California, 94143
| | | | - David S K Magnuson
- University of Louisville, Kentucky Spinal Cord Injury Research Center, Louisville, Kentucky, 40208
| | - Michael A Lane
- Department of Neurobiology and Anatomy, and the Marion Murray Spinal Cord Research Center, Drexel University, Philadelphia, Pennsylvania, 19129
| |
Collapse
|
19
|
Cheng L, Sami A, Ghosh B, Urban MW, Heinsinger NM, Liang SS, Smith GM, Wright MC, Li S, Lepore AC. LAR inhibitory peptide promotes recovery of diaphragm function and multiple forms of respiratory neural circuit plasticity after cervical spinal cord injury. Neurobiol Dis 2020; 147:105153. [PMID: 33127470 PMCID: PMC7726004 DOI: 10.1016/j.nbd.2020.105153] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 09/14/2020] [Accepted: 10/25/2020] [Indexed: 12/18/2022] Open
Abstract
Chondroitin sulfate proteoglycans (CSPGs), up-regulated in and around the lesion after traumatic spinal cord injury (SCI), are key extracellular matrix inhibitory molecules that limit axon growth and consequent recovery of function. CSPG-mediated inhibition occurs via interactions with axonal receptors, including leukocyte common antigen- related (LAR) phosphatase. We tested the effects of a novel LAR inhibitory peptide in rats after hemisection at cervical level 2, a SCI model in which bulbospinal inspiratory neural circuitry originating in the medullary rostral ventral respiratory group (rVRG) becomes disconnected from phrenic motor neuron (PhMN) targets in cervical spinal cord, resulting in persistent partial-to-complete diaphragm paralysis. LAR peptide was delivered by a soaked gelfoam, which was placed directly over the injury site immediately after C2 hemisection and replaced at 1 week post-injury. Axotomized rVRG axons originating in ipsilateral medulla or spared rVRG fibers originating in contralateral medulla were separately assessed by anterograde tracing via AAV2-mCherry injection into rVRG. At 8 weeks post-hemisection, LAR peptide significantly improved ipsilateral hemidiaphragm function, as assessed in vivo with electromyography recordings. LAR peptide promoted robust regeneration of ipsilateral-originating rVRG axons into and through the lesion site and into intact caudal spinal cord to reach PhMNs located at C3-C5 levels. Furthermore, regenerating rVRG axons re-established putative monosynaptic connections with their PhMNs targets. In addition, LAR peptide stimulated robust sprouting of both modulatory serotonergic axons and contralateral-originating rVRG fibers within the PhMN pool ipsilateral/ caudal to the hemisection. Our study demonstrates that targeting LAR-based axon growth inhibition promotes multiple forms of respiratory neural circuit plasticity and provides a new peptide-based therapeutic strategy to ameliorate the devastating respiratory consequences of SCI.
Collapse
Affiliation(s)
- Lan Cheng
- Department of Neuroscience, Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - Armin Sami
- Department of Neuroscience, Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - Biswarup Ghosh
- Department of Neuroscience, Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - Mark W Urban
- Department of Neuroscience, Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - Nicolette M Heinsinger
- Department of Neuroscience, Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - Sophia S Liang
- Department of Neuroscience, Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - George M Smith
- Department of Neuroscience, Shriners Hospitals for Pediatric Research Center, Temple University School of Medicine, 3500 North Broad Street, Philadelphia, PA 19140-5104, United States of America
| | - Megan C Wright
- Department of Biology, Arcadia University, Glenside, PA 19038, United States of America
| | - Shuxin Li
- Department of Anatomy and Cell Biology, Shriners Hospitals for Pediatric Research Center, Temple University School of Medicine, 3500 North Broad Street, Philadelphia, PA 19140-5104, United States of America
| | - Angelo C Lepore
- Department of Neuroscience, Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA 19107, United States of America.
| |
Collapse
|
20
|
Wollman LB, Streeter KA, Fusco AF, Gonzalez-Rothi EJ, Sandhu MS, Greer JJ, Fuller DD. Ampakines stimulate phrenic motor output after cervical spinal cord injury. Exp Neurol 2020; 334:113465. [PMID: 32949571 DOI: 10.1016/j.expneurol.2020.113465] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 08/31/2020] [Accepted: 09/14/2020] [Indexed: 12/21/2022]
Abstract
Activation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors increases phrenic motor output. Ampakines are a class of drugs that are positive allosteric modulators of AMPA receptors. We hypothesized that 1) ampakines can stimulate phrenic activity after incomplete cervical spinal cord injury (SCI), and 2) pairing ampakines with brief hypoxia could enable sustained facilitation of phrenic bursting. Phrenic activity was recorded ipsilateral (IL) and contralateral (CL) to C2 spinal cord hemisection (C2Hx) in anesthetized adult rats. Two weeks after C2Hx, ampakine CX717 (15 mg/kg, i.v.) increased IL (61 ± 46% baseline, BL) and CL burst amplitude (47 ± 26%BL) in 8 of 8 rats. After 90 min, IL and CL bursting remained above baseline (BL) in 7 of 8 rats. Pairing ampakine with a single bout of acute hypoxia (5-min, arterial partial pressure of O2 ~ 50 mmHg) had a variable impact on phrenic bursting, with some rats showing a large facilitation that exceeded the response of the ampakine alone group. At 8 weeks post-C2Hx, 7 of 8 rats increased IL (115 ± 117%BL) and CL burst amplitude (45 ± 27%BL) after ampakine. The IL burst amplitude remained above BL for 90-min in 7 of 8 rats; CL bursting remained elevated in 6 of 8 rats. The sustained impact of ampakine at 8 weeks was not enhanced by hypoxia exposure. Intravenous vehicle (10% 2-Hydroxypropyl-β-cyclodextrin) did not increase phrenic bursting at either time point. We conclude that ampakines effectively stimulate neural drive to the diaphragm after cervical SCI. Pairing ampakines with a single hypoxic exposure did not consistently enhance phrenic motor facilitation.
Collapse
Affiliation(s)
- L B Wollman
- Department of Physical Therapy, University of Florida, Gainesville, FL 32610, United States of America; Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL 32610, United States of America
| | - K A Streeter
- Department of Physical Therapy, University of Florida, Gainesville, FL 32610, United States of America; Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL 32610, United States of America
| | - A F Fusco
- Department of Physical Therapy, University of Florida, Gainesville, FL 32610, United States of America
| | - E J Gonzalez-Rothi
- Department of Physical Therapy, University of Florida, Gainesville, FL 32610, United States of America; McKnight Brain Institute, University of Florida, Gainesville, Florida 32610, United States of America; Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL 32610, United States of America
| | - M S Sandhu
- Department of Physical Therapy, University of Florida, Gainesville, FL 32610, United States of America
| | - J J Greer
- Department of Physiology, University of Alberta, Edmonton, AB T6G2SE, Canada
| | - D D Fuller
- Department of Physical Therapy, University of Florida, Gainesville, FL 32610, United States of America; McKnight Brain Institute, University of Florida, Gainesville, Florida 32610, United States of America; Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL 32610, United States of America.
| |
Collapse
|
21
|
Sunshine MD, Sutor TW, Fox EJ, Fuller DD. Targeted activation of spinal respiratory neural circuits. Exp Neurol 2020; 328:113256. [PMID: 32087253 DOI: 10.1016/j.expneurol.2020.113256] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 01/31/2020] [Accepted: 02/18/2020] [Indexed: 12/30/2022]
Abstract
Spinal interneurons which discharge in phase with the respiratory cycle have been repeatedly described over the last 50 years. These spinal respiratory interneurons are part of a complex propriospinal network that is synaptically coupled with respiratory motoneurons. This article summarizes current knowledge regarding spinal respiratory interneurons and emphasizes chemical, electrical and physiological methods for activating spinal respiratory neural circuits. Collectively, the work reviewed here shows that activating spinal interneurons can have a powerful impact on spinal respiratory motor output, and can even drive rhythmic bursting in respiratory motoneuron pools under certain conditions. We propose that the primary functions of spinal respiratory neurons include 1) shaping the respiratory pattern into the final efferent motor output from the spinal respiratory nerves; 2) coordinating respiratory muscle activation across the spinal neuraxis; 3) coordinating postural, locomotor and respiratory movements, and 4) enabling plasticity of respiratory motor output in health and disease.
Collapse
Affiliation(s)
- Michael D Sunshine
- Department of Physical Therapy, University of Florida, United States of America; McKnight Brain Institute, University of Florida, United States of America; Rehabilitation Science PhD Program, University of Florida, United States of America; Center for Respiratory Research and Rehabilitation, University of Florida, United States of America
| | - Tommy W Sutor
- Department of Physical Therapy, University of Florida, United States of America; Rehabilitation Science PhD Program, University of Florida, United States of America; Center for Respiratory Research and Rehabilitation, University of Florida, United States of America
| | - Emily J Fox
- Department of Physical Therapy, University of Florida, United States of America; Center for Respiratory Research and Rehabilitation, University of Florida, United States of America; Clinical Research Center, Brooks Rehabilitation, Jacksonville, FL, United States of America
| | - David D Fuller
- Department of Physical Therapy, University of Florida, United States of America; McKnight Brain Institute, University of Florida, United States of America; Center for Respiratory Research and Rehabilitation, University of Florida, United States of America.
| |
Collapse
|
22
|
Jensen VN, Alilain WJ, Crone SA. Role of Propriospinal Neurons in Control of Respiratory Muscles and Recovery of Breathing Following Injury. Front Syst Neurosci 2020; 13:84. [PMID: 32009911 PMCID: PMC6978673 DOI: 10.3389/fnsys.2019.00084] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 12/16/2019] [Indexed: 12/20/2022] Open
Abstract
Respiratory motor failure is the leading cause of death in spinal cord injury (SCI). Cervical injuries disrupt connections between brainstem neurons that are the primary source of excitatory drive to respiratory motor neurons in the spinal cord and their targets. In addition to direct connections from bulbospinal neurons, respiratory motor neurons also receive excitatory and inhibitory inputs from propriospinal neurons, yet their role in the control of breathing is often overlooked. In this review, we will present evidence that propriospinal neurons play important roles in patterning muscle activity for breathing. These roles likely include shaping the pattern of respiratory motor output, processing and transmitting sensory afferent information, coordinating ventilation with motor activity, and regulating accessory and respiratory muscle activity. In addition, we discuss recent studies that have highlighted the importance of propriospinal neurons for recovery of respiratory muscle function following SCI. We propose that molecular genetic approaches to target specific developmental neuron classes in the spinal cord would help investigators resolve the many roles of propriospinal neurons in the control of breathing. A better understanding of how spinal circuits pattern breathing could lead to new treatments to improve breathing following injury or disease.
Collapse
Affiliation(s)
- Victoria N. Jensen
- Neuroscience Graduate Program, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Warren J. Alilain
- Spinal Cord and Brain Injury Research Center, University of Kentucky College of Medicine, Lexington, KY, United States,Department of Neuroscience, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Steven A. Crone
- Division of Neurosurgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States,Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States,Department of Neurosurgery, University of Cincinnati College of Medicine, Cincinnati, OH, United States,*Correspondence: Steven A. Crone
| |
Collapse
|