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Holmes TC, Popp NM, Hintz CF, Dobrzycki I, Schmitz CJ, Schwichtenberg KA, Gonzalez-Rothi EJ, Sundberg CW, Streeter KA. Sex differences in spontaneous respiratory recovery following chronic C2 hemisection. J Appl Physiol (1985) 2024; 137:166-180. [PMID: 38867665 DOI: 10.1152/japplphysiol.00040.2024] [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: 01/16/2024] [Revised: 05/10/2024] [Accepted: 06/05/2024] [Indexed: 06/14/2024] Open
Abstract
Respiratory deficits after C2 hemisection (C2Hx) have been well documented through single-sex investigations. Although ovarian sex hormones enable enhanced respiratory recovery observed in females 2 wk post-C2Hx, it remains unknown if sex impacts spontaneous respiratory recovery at chronic time points. We conducted a longitudinal study to provide a comprehensive sex-based characterization of respiratory neuromuscular recovery for 8 wk after C2Hx. We recorded ventilation and chronic diaphragm electromyography (EMG) output in awake, behaving animals, phrenic motor output in anesthetized animals, and performed diaphragm muscle histology in chronically injured male and female rodents. Our results show that females expressed a greater recovery of tidal volume and minute ventilation compared with males during subacute and chronic time points. Eupneic diaphragm EMG amplitude during wakefulness and phrenic motor amplitude are similar between sexes at all time points after injury. Our data also suggest that females have a greater reduction in ipsilateral diaphragm EMG amplitude during spontaneous deep breaths (e.g., sighs) compared with males. Finally, we show evidence for atrophy and remodeling of the fast, fatigable fibers ipsilateral to injury in females, but not in males. To our knowledge, the data presented here represent the first study to report sex-dependent differences in spontaneous respiratory recovery and diaphragm muscle morphology following chronic C2Hx. These data highlight the need to study both sexes to inform evidence-based therapeutic interventions in respiratory recovery after spinal cord injury (SCI).NEW & NOTEWORTHY In response to chronic C2 hemisection, female rodents display increased tidal volume during eupneic breathing compared with males. Females show a greater reduction in diaphragm electromyography (EMG) amplitude during spontaneous deep breaths (e.g., sighs) and atrophy and remodeling of fast, fatigable diaphragm fibers. Given that most rehabilitative interventions occur in the subacute to chronic stages of injury, these results highlight the importance of considering sex when developing and evaluating therapeutics after spinal cord injury.
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Affiliation(s)
- Taylor C Holmes
- Exercise and Rehabilitation Science Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States
| | - Nicole M Popp
- Exercise and Rehabilitation Science Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States
| | - Carley F Hintz
- Exercise and Rehabilitation Science Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States
| | - Isabell Dobrzycki
- Exercise and Rehabilitation Science Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States
- Athletic and Human Performance Research Center, Marquette University, Milwaukee, Wisconsin, United States
| | - Carolyn J Schmitz
- Exercise and Rehabilitation Science Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States
| | - Kaylyn A Schwichtenberg
- Exercise and Rehabilitation Science Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States
| | - Elisa J Gonzalez-Rothi
- Department of Physical Therapy, University of Florida, Gainesville, Florida, United States
| | - Christopher W Sundberg
- Exercise and Rehabilitation Science Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States
- Athletic and Human Performance Research Center, Marquette University, Milwaukee, Wisconsin, United States
| | - Kristi A Streeter
- Exercise and Rehabilitation Science Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States
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Mickle AR, Peñaloza-Aponte JD, Coffey R, Hall NA, Baekey D, Dale EA. Closed-loop cervical epidural stimulation partially restores ipsilesional diaphragm EMG after acute C 2 hemisection. Respir Physiol Neurobiol 2024; 320:104182. [PMID: 37923238 PMCID: PMC11135909 DOI: 10.1016/j.resp.2023.104182] [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: 08/08/2023] [Revised: 10/22/2023] [Accepted: 10/22/2023] [Indexed: 11/07/2023]
Abstract
Cervical spinal cord injury creates lasting respiratory deficits which can require mechanical ventilation long-term. We have shown that closed-loop epidural stimulation (CL-ES) elicits respiratory plasticity in the form of increased phrenic network excitability (Malone et. al., E Neuro, Vol 9, 0426-21.2021, 2022); however, the ability of this treatment to create functional benefits for breathing function per se after injury has not been demonstrated. Here, we demonstrate in C2 hemisected anesthetized rats, a 20-minute bout of CL-ES administered at current amplitudes below the motor threshold restores paralyzed hemidiaphragm activity in-phase with breathing while potentiating contralesional activity. While this acute bout of stimulation did not elicit the increased network excitability seen in our chronic model, a subset of stimulated animals continued spontaneous ipsilesional diaphragm activity for several seconds after stopping stimulation. These results support the use of CL-ES as a therapeutic to rescue breathing after high cervical spinal cord injury, with the potential to lead to lasting recovery and device independence.
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Affiliation(s)
- Alyssa R Mickle
- Department of Neuroscience, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; Breathing Research and Therapeutics Center, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; McKnight Brain Institute, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States.
| | - Jesús D Peñaloza-Aponte
- Department of Neuroscience, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; Breathing Research and Therapeutics Center, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; McKnight Brain Institute, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States
| | - Richard Coffey
- Department of Physiology and Aging, University of Florida, 1600 SW Archer Rd M552, Gainesville, FL 32603, United States
| | - Natale A Hall
- Department of Physiology and Aging, University of Florida, 1600 SW Archer Rd M552, Gainesville, FL 32603, United States
| | - David Baekey
- Department of Neuroscience, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; Breathing Research and Therapeutics Center, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; McKnight Brain Institute, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States
| | - Erica A Dale
- Department of Neuroscience, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; Breathing Research and Therapeutics Center, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; McKnight Brain Institute, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; Department of Physiology and Aging, University of Florida, 1600 SW Archer Rd M552, Gainesville, FL 32603, United States
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Huang R, Worrell J, Garner E, Wang S, Homsey T, Xu B, Galer EL, Zhou Y, Tavakol S, Daneshvar M, Le T, Vinters HV, Salamon N, McArthur DL, Nuwer MR, Wu I, Leiter JC, Lu DC. Epidural electrical stimulation of the cervical spinal cord opposes opioid-induced respiratory depression. J Physiol 2022; 600:2973-2999. [PMID: 35639046 DOI: 10.1113/jp282664] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 03/25/2022] [Indexed: 02/02/2023] Open
Abstract
Opioid overdose suppresses brainstem respiratory circuits, causes apnoea and may result in death. Epidural electrical stimulation (EES) at the cervical spinal cord facilitated motor activity in rodents and humans, and we hypothesized that EES of the cervical spinal cord could antagonize opioid-induced respiratory depression in humans. Eighteen patients requiring surgical access to the dorsal surface of the spinal cord between C2 and C7 received EES or sham stimulation for up to 90 s at 5 or 30 Hz during complete (OFF-State) or partial suppression (ON-State) of respiration induced by remifentanil. During the ON-State, 30 Hz EES at C4 and 5 Hz EES at C3/4 increased tidal volume and decreased the end-tidal carbon dioxide level compared to pre-stimulation control levels. EES of 5 Hz at C5 and C7 increased respiratory frequency compared to pre-stimulation control levels. In the OFF-State, 30 Hz cervical EES at C3/4 terminated apnoea and induced rhythmic breathing. In cadaveric tissue obtained from a brain bank, more neurons expressed both the neurokinin 1 receptor (NK1R) and somatostatin (SST) in the cervical spinal levels responsive to EES (C3/4, C6 and C7) compared to a region non-responsive to EES (C2). Thus, the capacity of cervical EES to oppose opioid depression of respiration may be mediated by NK1R+/SST+ neurons in the dorsal cervical spinal cord. This study provides proof of principle that cervical EES may provide a novel therapeutic approach to augment respiratory activity when the neural function of the central respiratory circuits is compromised by opioids or other pathological conditions. KEY POINTS: Epidural electrical stimulation (EES) using an implanted spinal cord stimulator (SCS) is an FDA-approved method to manage chronic pain. We tested the hypothesis that cervical EES facilitates respiration during administration of opioids in 18 human subjects who were treated with low-dose remifentanil that suppressed respiration (ON-State) or high-dose remifentanil that completely inhibited breathing (OFF-State) during the course of cervical surgery. Dorsal cervical EES of the spinal cord augmented the respiratory tidal volume or increased the respiratory frequency, and the response to EES varied as a function of the stimulation frequency (5 or 30 Hz) and the cervical level stimulated (C2-C7). Short, continuous cervical EES restored a cyclic breathing pattern (eupnoea) in the OFF-State, suggesting that cervical EES reversed the opioid-induced respiratory depression. These findings add to our understanding of respiratory pattern modulation and suggest a novel mechanism to oppose the respiratory depression caused by opioids.
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Affiliation(s)
- Ruyi Huang
- Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.,Neuromotor Recovery and Rehabilitation Center, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.,Interdepartmental Program in Neuroscience, University of California, Los Angeles, CA, USA
| | - Jason Worrell
- Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.,Neuromotor Recovery and Rehabilitation Center, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Eric Garner
- Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Stephanie Wang
- Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.,Neuromotor Recovery and Rehabilitation Center, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Tali Homsey
- Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.,Neuromotor Recovery and Rehabilitation Center, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Bo Xu
- Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.,Neuromotor Recovery and Rehabilitation Center, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Erika L Galer
- Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.,Neuromotor Recovery and Rehabilitation Center, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.,Molecular, Cellular, Integrated Physiology Program, University of California, Los Angeles, CA, USA
| | - Yan Zhou
- Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.,Neuromotor Recovery and Rehabilitation Center, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Sherwin Tavakol
- Department of Neurosurgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Meelod Daneshvar
- University of California Fresno, Department of Surgery, Fresno, CA, USA
| | - Timothy Le
- Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.,Neuromotor Recovery and Rehabilitation Center, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Harry V Vinters
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.,Brain Research Institute, University of California, Los Angeles, CA, USA
| | - Noriko Salamon
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - David L McArthur
- Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Marc R Nuwer
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Irene Wu
- Department of Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - James C Leiter
- Department of Molecular and Systems Biology, Geisel School of Medicine, Lebanon, NH, USA
| | - Daniel C Lu
- Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.,Neuromotor Recovery and Rehabilitation Center, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.,Interdepartmental Program in Neuroscience, University of California, Los Angeles, CA, USA.,Brain Research Institute, University of California, Los Angeles, CA, USA
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