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Pisanski A, Prostebby M, Dickson CT, Pagliardini S. Mapping responses to focal injections of bicuculline in the lateral parafacial region identifies core regions for maximal generation of active expiration. eLife 2024; 13:RP94276. [PMID: 39017665 PMCID: PMC11254382 DOI: 10.7554/elife.94276] [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: 07/18/2024] Open
Abstract
The lateral parafacial area (pFL) is a crucial region involved in respiratory control, particularly in generating active expiration through an expiratory oscillatory network. Active expiration involves rhythmic abdominal (ABD) muscle contractions during late-expiration, increasing ventilation during elevated respiratory demands. The precise anatomical location of the expiratory oscillator within the ventral medulla's rostro-caudal axis is debated. While some studies point to the caudal tip of the facial nucleus (VIIc) as the oscillator's core, others suggest more rostral areas. Our study employed bicuculline (a γ-aminobutyric acid type A [GABA-A] receptor antagonist) injections at various pFL sites (-0.2 mm to +0.8 mm from VIIc) to investigate the impact of GABAergic disinhibition on respiration. These injections consistently elicited ABD recruitment, but the response strength varied along the rostro-caudal zone. Remarkably, the most robust and enduring changes in tidal volume, minute ventilation, and combined respiratory responses occurred at more rostral pFL locations (+0.6/+0.8 mm from VIIc). Multivariate analysis of the respiratory cycle further differentiated between locations, revealing the core site for active expiration generation with this experimental approach. Our study advances our understanding of neural mechanisms governing active expiration and emphasizes the significance of investigating the rostral pFL region.
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Affiliation(s)
| | - Mitchell Prostebby
- Neuroscience and Mental Health Institute, University of AlbertaEdmontonCanada
| | - Clayton T Dickson
- Department of Physiology, University of AlbertaEdmontonCanada
- Neuroscience and Mental Health Institute, University of AlbertaEdmontonCanada
- Department of Psychology, University of AlbertaEdmontonCanada
- Department of Anesthesiology and Pain Medicine, University of AlbertaEdmontonCanada
- Women and Children’s Health Research Institute, University of AlbertaEdmontonCanada
| | - Silvia Pagliardini
- Department of Physiology, University of AlbertaEdmontonCanada
- Neuroscience and Mental Health Institute, University of AlbertaEdmontonCanada
- Department of Anesthesiology and Pain Medicine, University of AlbertaEdmontonCanada
- Women and Children’s Health Research Institute, University of AlbertaEdmontonCanada
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2
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Bernardes-Ribeiro M, Patrone LGA, Cristina-Silva C, Bícego KC, Gargaglioni LH. Exercise derived myokine irisin as mediator of cardiorespiratory, metabolic and thermal adjustments during central and peripheral chemoreflex activation. Sci Rep 2024; 14:12262. [PMID: 38806563 PMCID: PMC11133352 DOI: 10.1038/s41598-024-62650-7] [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: 11/07/2023] [Accepted: 05/20/2024] [Indexed: 05/30/2024] Open
Abstract
Exercise elicits physiological adaptations, including hyperpnea. However, the mechanisms underlying exercise-induced hyperpnea remain unresolved. Skeletal muscle acts as a secretory organ, releasing irisin (IR) during exercise. Irisin can cross the blood-brain barrier, influencing muscle and tissue metabolism, as well as signaling in the central nervous system (CNS). We evaluated the effect of intracerebroventricular or intraperitoneal injection of IR in adult male rats on the cardiorespiratory and metabolic function during sleep-wake cycle under room air, hypercapnia and hypoxia. Central IR injection caused an inhibition on ventilation (VE) during wakefulness under normoxia, while peripheral IR reduced VE during sleep. Additionally, central IR exacerbates hypercapnic hyperventilation by increasing VE and reducing oxygen consumption. As to cardiovascular regulation, central IR caused an increase in heart rate (HR) across all conditions, while no change was observed following peripheral administration. Finally, central IR attenuated the hypoxia-induced regulated hypothermia and increase sleep episodes, while peripheral IR augmented CO2-induced hypothermia, during wakefulness. Overall, our results suggest that IR act mostly on CNS exerting an inhibitory effect on breathing under resting conditions, while stimulating the hypercapnic ventilatory response and increasing HR. Therefore, IR seems not to be responsible for the exercise-induced hyperpnea, but contributes to the increase in HR.
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Affiliation(s)
- Mariana Bernardes-Ribeiro
- Departamento de Morfologia e Fisiologia Animal, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP/FCAV), Via de Acesso Paulo Donato Castellane s/n, Jaboticabal, SP, 14870-000, Brazil
| | - Luis Gustavo A Patrone
- Departamento de Morfologia e Fisiologia Animal, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP/FCAV), Via de Acesso Paulo Donato Castellane s/n, Jaboticabal, SP, 14870-000, Brazil
| | - Caroline Cristina-Silva
- Departamento de Morfologia e Fisiologia Animal, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP/FCAV), Via de Acesso Paulo Donato Castellane s/n, Jaboticabal, SP, 14870-000, Brazil
| | - Kênia C Bícego
- Departamento de Morfologia e Fisiologia Animal, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP/FCAV), Via de Acesso Paulo Donato Castellane s/n, Jaboticabal, SP, 14870-000, Brazil
| | - Luciane H Gargaglioni
- Departamento de Morfologia e Fisiologia Animal, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP/FCAV), Via de Acesso Paulo Donato Castellane s/n, Jaboticabal, SP, 14870-000, Brazil.
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3
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Umezu HL, Bittencourt-Silva PG, Mourão FAG, Moreira FA, Moraes MFD, Santos VR, da Silva GSF. Respiratory activity during seizures induced by pentylenetetrazole. Respir Physiol Neurobiol 2024; 323:104229. [PMID: 38307440 DOI: 10.1016/j.resp.2024.104229] [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: 11/25/2023] [Revised: 01/27/2024] [Accepted: 01/29/2024] [Indexed: 02/04/2024]
Abstract
This study investigated the respiratory activity in adult Wistar rats across different behavioral seizure severity induced by pentylenetetrazole (PTZ). Animals underwent surgery for electrodes implantation, allowing simultaneous EEG and diaphragm EMG (DIAEMG) recordings and the respiratory frequency and DIAEMG amplitude were measured. Seizures were acutely induced through PTZ injection and classified based on a pre-established score, with absence-like seizures (spike wave discharge (SWD) events on EEG) representing the lowest score. The respiratory activity was grouped into the different seizure severities. During absence-like and myoclonic jerk seizures, the breathing frequency decreased significantly (∼50% decrease) compared to pre- and post-ictal periods. Pronounced changes occurred with more severe seizures (clonic and tonic) with periods of apnea, especially during tonic seizures. Apnea duration was significantly higher in tonic compared to clonic seizures. Notably, during PTZ-induced tonic seizures the apnea events were marked by tonic DIAEMG contraction (tonic-phase apnea). In the majority of animals (5 out of 7) this was a fatal event in which the seizure-induced respiratory arrest preceded the asystole. In conclusion, we provide an assessment of the respiratory activity in the PTZ-induced acute seizures and showed that breathing dysfunction is more pronounced in seizures with higher severity.
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Affiliation(s)
- Hanna L Umezu
- Department of Physiology and Biophysics, Institute of Biological Science, Federal University of Minas Gerais (ICB/UFMG), Belo Horizonte, Brazil
| | - Paloma G Bittencourt-Silva
- Department of Physiology and Biophysics, Institute of Biological Science, Federal University of Minas Gerais (ICB/UFMG), Belo Horizonte, Brazil
| | - Flávio A G Mourão
- Department of Physiology and Biophysics, Institute of Biological Science, Federal University of Minas Gerais (ICB/UFMG), Belo Horizonte, Brazil; Graduate Program in Neuroscience, Institute of Biological Science, Federal University of Minas Gerais (ICB/UFMG), Belo Horizonte, Brazil
| | - Fabrício A Moreira
- Department of Pharmacology, Institute of Biological Science, Federal University of Minas Gerais (ICB/UFMG), Belo Horizonte, Brazil
| | - Márcio Flávio D Moraes
- Department of Physiology and Biophysics, Institute of Biological Science, Federal University of Minas Gerais (ICB/UFMG), Belo Horizonte, Brazil; Graduate Program in Neuroscience, Institute of Biological Science, Federal University of Minas Gerais (ICB/UFMG), Belo Horizonte, Brazil
| | - Victor R Santos
- Department of Morphology, Institute of Biological Science, Federal University of Minas Gerais (ICB/UFMG), Belo Horizonte, Brazil
| | - Glauber S F da Silva
- Department of Physiology and Biophysics, Institute of Biological Science, Federal University of Minas Gerais (ICB/UFMG), Belo Horizonte, Brazil.
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4
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Khurram OU, Mantilla CB, Sieck GC. Neuromotor control of spontaneous quiet breathing in awake rats evaluated by assessments of diaphragm EMG stationarity. J Neurophysiol 2023; 130:1344-1357. [PMID: 37877195 DOI: 10.1152/jn.00267.2023] [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: 07/10/2023] [Revised: 10/23/2023] [Accepted: 10/23/2023] [Indexed: 10/26/2023] Open
Abstract
The neuromotor control of the diaphragm muscle (DIAm) is dynamic. The activity of the DIAm can be recorded via electromyography (EMG), which represents the temporal summation of motor unit action potentials. Our goal in the present study was to investigate DIAm neuromotor control during quiet spontaneous breathing (eupnea) in awake rats by evaluating DIAm EMG at specific temporal locations defined by motor unit recruitment and derecruitment. We evaluated the nonstationarity of DIAm EMG activity to identify DIAm motor unit recruitment and derecruitment durations. Combined with assessments of root mean square (RMS) and sum of squares (SS) EMG, the durations of these phases provide physiological information about the temporal aspects of motor control. During eupnea in awake rats (n = 10), the duration of motor unit recruitment comprised 61 ± 19 ms of the onset-to-peak duration (214 ± 62 ms) of the DIAm RMS EMG. The peak-to-offset duration of DIAm EMG activity was 453 ± 96 ms, with a terminating period of derecruitment of 161 ± 44 ms. The burst duration was 673 ± 128 ms. Both the RMS EMG amplitude and the SS EMG were higher at the completion of motor unit recruitment than at the start of motor unit derecruitment, suggesting that offset discharge rates were lower than onset discharge rates. Our analyses provide novel insights into the time domain aspects of DIAm neuromotor control and allow indirect estimates of the contribution of recruitment and frequency to RMS EMG amplitude during eupnea in awake rats.NEW & NOTEWORTHY We characterized three phases of neuromotor control-motor unit recruitment, sustained activity, and derecruitment-based on statistical assessments of stationarity of the diaphragm muscle (DIAm) EMG activity in awake rats. Our findings may allow indirect estimates of the contribution of motor unit recruitment and frequency coding toward generating force and provide novel insights about the temporal aspects of DIAm neuromotor control and descending respiratory drive in unanesthetized animals.
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Affiliation(s)
- Obaid U Khurram
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, United States
| | - Carlos B Mantilla
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, United States
- Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Gary C Sieck
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, United States
- Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
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5
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Casarrubios AM, Pérez-Atencio LF, Martín C, Ibarz JM, Mañas E, Paul DL, Barrio LC. Neural bases for the genesis and CO 2 therapy of periodic Cheyne-Stokes breathing in neonatal male connexin-36 knockout mice. Front Neurosci 2023; 17:1045269. [PMID: 36845442 PMCID: PMC9944137 DOI: 10.3389/fnins.2023.1045269] [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: 09/15/2022] [Accepted: 01/16/2023] [Indexed: 02/11/2023] Open
Abstract
Periodic Cheyne-Stokes breathing (CSB) oscillating between apnea and crescendo-decrescendo hyperpnea is the most common central apnea. Currently, there is no proven therapy for CSB, probably because the fundamental pathophysiological question of how the respiratory center generates this form of breathing instability is still unresolved. Therefore, we aimed to determine the respiratory motor pattern of CSB resulting from the interaction of inspiratory and expiratory oscillators and identify the neural mechanism responsible for breathing regularization induced by the supplemental CO2 administration. Analysis of the inspiratory and expiratory motor pattern in a transgenic mouse model lacking connexin-36 electrical synapses, the neonatal (P14) Cx36 knockout male mouse, with a persistent CSB, revealed that the reconfigurations recurrent between apnea and hyperpnea and vice versa result from cyclical turn on/off of active expiration driven by the expiratory oscillator, which acts as a master pacemaker of respiration and entrains the inspiratory oscillator to restore ventilation. The results also showed that the suppression of CSB by supplemental 12% CO2 in inhaled air is due to the stabilization of coupling between expiratory and inspiratory oscillators, which causes the regularization of respiration. CSB rebooted after washout of CO2 excess when the inspiratory activity depressed again profoundly, indicating that the disability of the inspiratory oscillator to sustain ventilation is the triggering factor of CSB. Under these circumstances, the expiratory oscillator activated by the cyclic increase of CO2 behaves as an "anti-apnea" center generating the crescendo-decrescendo hyperpnea and periodic breathing. The neurogenic mechanism of CSB identified highlights the plasticity of the two-oscillator system in the neural control of respiration and provides a rationale base for CO2 therapy.
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Affiliation(s)
- Ana M. Casarrubios
- Units of Experimental Neurology and Sleep Apnea, Hospital “Ramón y Cajal” (IRYCIS), Madrid, Spain,Ph.D. Program in Neuroscience, Autonoma de Madrid University-Cajal Institute, Madrid, Spain
| | - Leonel F. Pérez-Atencio
- Units of Experimental Neurology and Sleep Apnea, Hospital “Ramón y Cajal” (IRYCIS), Madrid, Spain
| | - Cristina Martín
- Units of Experimental Neurology and Sleep Apnea, Hospital “Ramón y Cajal” (IRYCIS), Madrid, Spain
| | - José M. Ibarz
- Units of Experimental Neurology and Sleep Apnea, Hospital “Ramón y Cajal” (IRYCIS), Madrid, Spain
| | - Eva Mañas
- Sleep Apnea Unit, Respiratory Department, Hospital “Ramón y Cajal” (IRYCIS), Madrid, Spain
| | - David L. Paul
- Department of Neurobiology, Medical School, Harvard University, Boston, MA, United States
| | - Luis C. Barrio
- Units of Experimental Neurology and Sleep Apnea, Hospital “Ramón y Cajal” (IRYCIS), Madrid, Spain,Center for Biomedical Technology, Universidad Politécnica de Madrid, Madrid, Spain,*Correspondence: Luis C. Barrio, ; orcid.org/0000-0002-9016-3510
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6
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Toledo C, Andrade DC, Diaz-Jara E, Ortolani D, Bernal-Santander I, Schwarz KG, Ortiz FC, Marcus NJ, Oliveira LM, Takakura AC, Moreira TS, Del Rio R. Cardiorespiratory alterations following intermittent photostimulation of RVLM C1 neurons: Implications for long-term blood pressure, breathing and sleep regulation in freely moving rats. Acta Physiol (Oxf) 2022; 236:e13864. [PMID: 35959519 DOI: 10.1111/apha.13864] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 01/29/2023]
Abstract
AIM Sympathoexcitation and sleep-disordered breathing are common contributors for disease progression. Catecholaminergic neurons from the rostral ventrolateral medulla (RVLM-C1) modulate sympathetic outflow and have anatomical projections to respiratory neurons; however, the contribution of highly selective activation of RVLM-C1 neurons on long-term autonomic and breathing (dys)regulation remains to be understood. METHODS To explore this relationship, a lentiviral vector carrying the light-sensitive cation channel channelrhodopsin-2 (LVV-PRSX8-ChR2-YFP) was unilaterally injected into the RVLM of healthy rats. On the contralateral side, LVV-PRSX8-ChR2-YFP was co-injected with a specific immunotoxin (DβH-SAP) targeted to eliminate C1 neurons. RESULTS Intermittent photostimulation of RVLM-C1 in vivo, in unrestrained freely moving rats, elicited long-term facilitation of the sympathetic drive, a rise in blood pressure and sympatho-respiratory coupling. In addition, photoactivation of RVLM-C1 induced long-lasting ventilatory instability, characterized by oscillations in tidal volume and increased breathing variability, but only during non-rapid eye movement sleep. These effects were not observed when photostimulation of the RVLM was performed in the presence of DβH-SAP toxin. CONCLUSIONS The finding that intermittent activation of RVLM-C1 neurons induces autonomic and breathing dysfunction suggest that episodic stimulation of RVLM-C1 may serve as a pathological substrate for the long-term development of cardiorespiratory disorders.
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Affiliation(s)
- Camilo Toledo
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - David C Andrade
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Fisiología y Medicina de Altura, Departamento Biomedico, Facultad de Ciencias de la Salud, Universidad de Antofagasta, Antofagasta, Chile
| | - Esteban Diaz-Jara
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Domiziana Ortolani
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Ignacio Bernal-Santander
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Karla G Schwarz
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Fernando C Ortiz
- Mechanisms of Myelin Formation and Repair Laboratory, Facultad de Ciencias de la Salud, Instituto de Ciencias Biomédicas, Universidad, Autónoma de Chile, Santiago, Chile
| | - Noah J Marcus
- Department of Physiology and Pharmacology, Des Moines University, Des Moines, Iowa, USA
| | - Luiz M Oliveira
- Department of Pharmacology, Institute of Biomedical Science, University of Sao Paulo, Sao Paulo, Brazil
| | - Ana C Takakura
- Department of Pharmacology, Institute of Biomedical Science, University of Sao Paulo, Sao Paulo, Brazil
| | - Thiago S Moreira
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of Sao Paulo, Sao Paulo, Brazil
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Envejecimiento y Regeneración (CARE), Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile
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7
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Bhandare A, van de Wiel J, Roberts R, Braren I, Huckstepp R, Dale N. Analyzing the brainstem circuits for respiratory chemosensitivity in freely moving mice. eLife 2022; 11:e70671. [PMID: 36300918 PMCID: PMC9643001 DOI: 10.7554/elife.70671] [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: 05/25/2021] [Accepted: 10/12/2022] [Indexed: 11/13/2022] Open
Abstract
Regulation of systemic PCO2 is a life-preserving homeostatic mechanism. In the medulla oblongata, the retrotrapezoid nucleus (RTN) and rostral medullary Raphe are proposed as CO2 chemosensory nuclei mediating adaptive respiratory changes. Hypercapnia also induces active expiration, an adaptive change thought to be controlled by the lateral parafacial region (pFL). Here, we use GCaMP6 expression and head-mounted mini-microscopes to image Ca2+ activity in these nuclei in awake adult mice during hypercapnia. Activity in the pFL supports its role as a homogenous neuronal population that drives active expiration. Our data show that chemosensory responses in the RTN and Raphe differ in their temporal characteristics and sensitivity to CO2, raising the possibility these nuclei act in a coordinated way to generate adaptive ventilatory responses to hypercapnia. Our analysis revises the understanding of chemosensory control in awake adult mouse and paves the way to understanding how breathing is coordinated with complex non-ventilatory behaviours.
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Affiliation(s)
- Amol Bhandare
- School of Life Sciences, University of WarwickCoventryUnited Kingdom
| | | | - Reno Roberts
- School of Life Sciences, University of WarwickCoventryUnited Kingdom
| | - Ingke Braren
- University Medical Center Eppendorf, Vector Facility, Institute of Experimental Pharmacology and ToxicologyHamburgGermany
| | - Robert Huckstepp
- School of Life Sciences, University of WarwickCoventryUnited Kingdom
| | - Nicholas Dale
- School of Life Sciences, University of WarwickCoventryUnited Kingdom
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8
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da Silva MP, Spiller PF, Paton JFR, Moraes DJA. Peripheral chemoreflex activation induces expiratory but not inspiratory excitation of C1 pre-sympathetic neurones of rats. Acta Physiol (Oxf) 2022; 235:e13853. [PMID: 35722749 DOI: 10.1111/apha.13853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 06/10/2022] [Accepted: 06/16/2022] [Indexed: 11/30/2022]
Abstract
AIMS Stimulation of peripheral chemoreceptors, as during hypoxia, increases breathing and respiratory-related sympathetic bursting. Activation of catecholaminergic C1 neurones induces sympathoexcitation, while its ablation reduces the chemoreflex sympathoexcitatory response. However, no study has determined the respiratory phase(s) in which the pre-sympathetic C1 neurones are recruited by peripheral chemoreceptor and whether C1 neurone activation affects all phases of respiratory modulation of sympathetic activity. We addressed these unknowns by testing the hypothesis that peripheral chemoreceptor activation excites pre-sympathetic C1 neurones during inspiration and expiration. METHODS Using the in situ preparation of rat, we made intracellular recordings from baroreceptive pre-sympathetic C1 neurones during peripheral chemoreflex stimulation. We optogenetically activated C1 neurones selectively and compared any respiratory-phase-related increases in sympathetic activity with that which occurs following stimulation of the peripheral chemoreflex. RESULTS Activation of peripheral chemoreceptors using cytotoxic hypoxia (potassium cyanide) increased the firing frequency of C1 neurones and both the frequency and amplitude of their excitatory post-synaptic currents during the phase of expiration only. In contrast, optogenetic stimulation of C1 neurones activates inspiratory neurones, which secondarily inhibit expiratory neurones, but produced comparable increases in sympathetic activity across all phases of respiration. CONCLUSION Our data reveal that the peripheral chemoreceptor-mediated expiratory-related sympathoexcitation is mediated through excitation of expiratory neurones antecedent to C1 pre-sympathetic neurones; these may be found in the Kölliker-Fuse nucleus. Despite peripheral chemoreceptor excitation of inspiratory neurones, these do not trigger C1 neurone-mediated increases in sympathetic activity. These studies provide compelling novel insights into the functional organization of respiratory-sympathetic neural networks.
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Affiliation(s)
- Melina P da Silva
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil.,Department of Biophysics, Paulista School of Medicine, Federal University of São Paulo, São Paulo, SP, Brazil
| | - Pedro F Spiller
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Julian F R Paton
- Manaaki Manawa, The Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Davi J A Moraes
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
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9
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Abstract
Brain PCO2 is sensed primarily via changes in [H+]. Small pH changes are detected in the medulla oblongata and trigger breathing adjustments that help maintain arterial PCO2 constant. Larger perturbations of brain CO2/H+, possibly also sensed elsewhere in the CNS, elicit arousal, dyspnea, and stress, and cause additional breathing modifications. The retrotrapezoid nucleus (RTN), a rostral medullary cluster of glutamatergic neurons identified by coexpression of Phoxb and Nmb transcripts, is the lynchpin of the central respiratory chemoreflex. RTN regulates breathing frequency, inspiratory amplitude, and active expiration. It is exquisitely responsive to acidosis in vivo and maintains breathing autorhythmicity during quiet waking, slow-wave sleep, and anesthesia. The RTN response to [H+] is partly an intrinsic neuronal property mediated by proton sensors TASK-2 and GPR4 and partly a paracrine effect mediated by astrocytes and the vasculature. The RTN also receives myriad excitatory or inhibitory synaptic inputs including from [H+]-responsive neurons (e.g., serotonergic). RTN is silenced by moderate hypoxia. RTN inactivity (periodic or sustained) contributes to periodic breathing and, likely, to central sleep apnea. RTN development relies on transcription factors Egr2, Phox2b, Lbx1, and Atoh1. PHOX2B mutations cause congenital central hypoventilation syndrome; they impair RTN development and consequently the central respiratory chemoreflex.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, VA, United States.
| | - Douglas A Bayliss
- Department of Pharmacology, University of Virginia, Charlottesville, VA, United States
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10
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Saini JK, Janes TA, MacLean JE, Pagliardini S. Expiratory activity during sleep in children. J Sleep Res 2021; 31:e13539. [PMID: 34921704 DOI: 10.1111/jsr.13539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 12/02/2021] [Accepted: 12/02/2021] [Indexed: 11/29/2022]
Abstract
Sleep irregularities and respiratory events (apnea, O2 desaturation or a combination thereof) are often present in the infant population. While inspiration is the main active process in the act of breathing, expiration is generally thought to occur passively. Although commonly considered as quiet during sleep, expiratory abdominal muscles have been proposed to be recruited to promote ventilation, facilitate gas exchange, and reduce the work of breathing during conditions of increased respiratory drive, exercise, or airway obstruction. In this study, we investigated the occurrence of expiratory abdominal muscle activity in polysomnographic studies of subjects (aged 0-2 years) suspected of sleep disordered breathing. Our results indicate that abdominal muscle activation occurs during sleep, most frequently during non-rapid eye movement and rapid-eye movement states compared to slow-wave sleep. Furthermore, abdominal muscle activity was present during regular breathing or associated with respiratory events (apneas or O2 desaturation). In the latter case, abdominal muscle recruitment more frequently followed the onset of respiratory events and terminated with recovery from blood O2 desaturation events. We conclude that expiratory abdominal muscle activity contributes to the pattern of respiratory muscle recruitment during sleep in infants and given its temporal relationship with respiratory events, we propose that its recruitment could facilitate proper ventilation by counteracting airway resistance and O2 desaturation in infancy across different stages of sleep.
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Affiliation(s)
- Jasmeen K Saini
- Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry University of Alberta, Edmonton, Alberta, Canada.,Women and Children's Health Research Institute, Faculty of Medicine and Dentistry University of Alberta, Edmonton, Alberta, Canada
| | - Tara A Janes
- Women and Children's Health Research Institute, Faculty of Medicine and Dentistry University of Alberta, Edmonton, Alberta, Canada.,Department of Pediatrics, Faculty of Medicine and Dentistry University of Alberta, Edmonton, Alberta, Canada
| | - Joanna E MacLean
- Women and Children's Health Research Institute, Faculty of Medicine and Dentistry University of Alberta, Edmonton, Alberta, Canada.,Department of Pediatrics, Faculty of Medicine and Dentistry University of Alberta, Edmonton, Alberta, Canada.,Stollery Children's Hospital, Edmonton, Alberta, Canada
| | - Silvia Pagliardini
- Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry University of Alberta, Edmonton, Alberta, Canada.,Women and Children's Health Research Institute, Faculty of Medicine and Dentistry University of Alberta, Edmonton, Alberta, Canada.,Department of Physiology, Faculty of Medicine and Dentistry University of Alberta, Edmonton, Alberta, Canada
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11
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Pérez‐Atencio LF, Casarrubios AM, Ibarz JM, Barios JA, Medrano C, Pestaña D, Paul DL, Barrio LC. Respiratory disturbances and high risk of sudden death in the neonatal connexin-36 knockout mouse. Physiol Rep 2021; 9:e15109. [PMID: 34755471 PMCID: PMC8579078 DOI: 10.14814/phy2.15109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 10/10/2021] [Indexed: 11/24/2022] Open
Abstract
Neural circuits at the brainstem involved in the central generation of the motor patterns of respiration and cardiorespiratory chemoreflexes organize as cell assemblies connected by chemical and electrical synapses. However, the role played by the electrical connectivity mainly mediated by connexin36 (Cx36), which expression reaches peak value during the postnatal period, is still unknown. To address this issue, we analyzed here the respiratory phenotype of a mouse strain devoid constitutively of Cx36 at P14. Male Cx36-knockout mice at rest showed respiratory instability of variable degree, including a periodic Cheyne-Stokes breathing. Moreover, mice lacking Cx36 exhibited exacerbated chemoreflexes to normoxic and hypoxic hypercapnia characterized by a stronger inspiratory/expiratory coupling due to an increased sensitivity to CO2 . Deletion of Cx36 also impaired the generation of the recurrent episodes of transient bradycardia (ETBs) evoked during hypercapnic chemoreflexes; these EBTs constituted a powerful mechanism of cardiorespiratory coupling capable of improving alveolar gaseous exchange under hypoxic hypercapnia conditions. Approximately half of the homo- and heterozygous Cx36KO, but none WT, mice succumbed by respiratory arrest when submitted to hypoxia-hypercapnia, the principal exogenous stressor causing sudden infant death syndrome (SIDS). The early suppression of EBTs, which worsened arterial O2 saturation, and the generation of a paroxysmal generalized clonic-tonic activity, which provoked the transition from eupneic to gasping respiration, were the critical events causing sudden death in the Cx36KO mice. These results indicate that Cx36 expression plays a pivotal role in respiratory control, cardiorespiratory coordination, and protection against SIDS at the postnatal period.
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Affiliation(s)
| | - Ana M. Casarrubios
- Unit of Experimental Neurology“Ramón y Cajal” Hospital (IRYCIS)MadridSpain
| | - José M. Ibarz
- Unit of Experimental Neurology“Ramón y Cajal” Hospital (IRYCIS)MadridSpain
| | - Juan A. Barios
- Biomedical Neuroengineering Research Group (nBio)Systems Engineering and Automation Department of Miguel Hernández UniversityElcheSpain
| | - Cristina Medrano
- Anesthesiology Service“Ramón y Cajal” Hospital (IRYCIS)MadridSpain
| | - David Pestaña
- Anesthesiology Service“Ramón y Cajal” Hospital (IRYCIS)MadridSpain
| | - David L. Paul
- Department of NeurobiologyHarvard Medical SchoolBostonMassachusettsUSA
| | - Luis C. Barrio
- Unit of Experimental Neurology“Ramón y Cajal” Hospital (IRYCIS)MadridSpain
- Centro de Tecnología Biomédica de la Universidad PolitécnicaMadridSpain
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12
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Takakura AC, Malheiros-Lima MR, Moreira TS. Excitatory and inhibitory modulation of parafacial respiratory neurons in the control of active expiration. Respir Physiol Neurobiol 2021; 289:103657. [PMID: 33781931 DOI: 10.1016/j.resp.2021.103657] [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: 12/09/2020] [Revised: 02/22/2021] [Accepted: 03/21/2021] [Indexed: 01/21/2023]
Abstract
In order to increase ventilation, the respiratory system engages active expiration through recruitment of abdominal muscles. Here, we reviewed the new advances in the modulation of parafacial respiratory (pF) region to trigger active expiration. In addition, we also made a comprehensive discussion of experiments indicating that the lateral aspect of the pF (pFL) is anatomically and functionally distinct from the adjacent and partially overlapping chemosensitive neurons of the ventral aspect of the pF (pFV) also named the retrotrapezoid nucleus. Recent evidence suggest a complex network responsible for the generation of active expiration and neuromodulatory systems that influence its activity. The activity of the pFL is tonically inhibited by inhibitory inputs and also receives excitatory inputs from chemoreceptors (central x peripheral) as well as from catecholaminergic C1 neurons. Therefore, the modulatory inputs and the physiological conditions under which these mechanisms are used to recruit active expiration and increase ventilation need further investigation.
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Affiliation(s)
- Ana C Takakura
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, 05508-000, São Paulo, SP, Brazil.
| | - Milene R Malheiros-Lima
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, 05508-000, São Paulo, SP, Brazil
| | - Thiago S Moreira
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, 05508-000, São Paulo, SP, Brazil.
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13
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Leirão IP, Colombari DSA, da Silva GSF, Zoccal DB. Lesion of Serotonergic Afferents to the Retrotrapezoid Nucleus Impairs the Tachypneic Response to Hypercapnia in Unanesthetized Animals. Neuroscience 2020; 452:63-77. [PMID: 33212216 DOI: 10.1016/j.neuroscience.2020.11.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 10/30/2020] [Accepted: 11/03/2020] [Indexed: 12/17/2022]
Abstract
Hypercapnia promotes an increase in pulmonary ventilation due to the stimulation of brainstem chemosensory cells that are connected to the respiratory network. Among these cells are the raphe serotonergic neurons which widely send projections to distinct central respiratory compartments. Nevertheless, the physiological role of specific raphe serotonergic projections to other chemosensitive sites on the emergence of hypercapnia ventilatory response in vivo still remains to be elucidated. Here we investigated whether the ventilatory response to hypercapnia requires serotonergic inputs to the chemosensitive cells of the retrotrapezoid nucleus (RTN) in the ventrolateral medulla. To test this, pulmonary ventilation was evaluated under baseline conditions and during hypercapnia (7% CO2) in unanesthetized juvenile Holtzman rats (60-90 g) that received bilateral microinjections of either vehicle (control) or anti-SERT-SAP (0.1 mM, 10 pmol/100 nl) toxin in the RTN to retrogradely destroy serotonergic afferents to this region. Fifteen days after microinjections, baseline ventilation was not different between anti-SERT-SAP (n = 8) and control animals (n = 9). In contrast, the ablation of RTN-projecting serotonergic neurons markedly attenuated the hypercapnia-induced increase in respiratory frequency which was correlated with reduced numbers of serotonergic neurons in the raphe obscurus and magnus, but not in the raphe pallidus. The increase in tidal volume during hypercapnia was not significantly affected by anti-SERT-SAP microinjections in the RTN. Our data indicate that serotoninergic neurons that send projections to the RTN region are required for the processing of ventilatory reflex response during exposure to high CO2 in unanesthetized conditions.
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Affiliation(s)
- Isabela P Leirão
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Débora S A Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Glauber S F da Silva
- Department of Physiology and Biophysics. Institute of Biological Sciences, Federal University of Minas Gerais (ICB/UFMG), Belo Horizonte, MG, Brazil
| | - Daniel B Zoccal
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil.
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14
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Leirão IP, Zoccal DB, Gargaglioni LH, da Silva GSF. Differential modulation of active expiration during hypercapnia by the medullary raphe in unanesthetized rats. Pflugers Arch 2020; 472:1563-1576. [PMID: 32914212 DOI: 10.1007/s00424-020-02455-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 07/30/2020] [Accepted: 08/27/2020] [Indexed: 11/26/2022]
Abstract
Active expiration represents an important mechanism to improve ventilation in conditions of augmented ventilatory demand, such as hypercapnia. While a rostral ventromedullary region, the parafacial respiratory group (pFRG), has been identified as a conditional expiratory oscillator, little is known about how central chemosensitive sites contribute to modulate active expiration under hypercapnia. In this study, we investigated the influence of the medullary raphe in the emergence of phasic expiratory abdominal activity during hypercapnia in unanesthetized adult male rats, in a state-dependent manner. To do so, reverse microdialysis of muscimol (GABAA receptor agonist, 1 mM) or 8-OH-DPAT (5-HT1A agonist, 1 mM) was applied in the MR during sleep and wakefulness periods, both in normocapnic (room air) and hypercapnic conditions (7% CO2). Electromyography (EMG) of diaphragm and abdominal muscles was performed to measure inspiratory and expiratory motor outputs. We found that active expiration did not occur in room air exposure during wakefulness or sleep. However, hypercapnia did recruit active expiration, and differential effects were observed with the drug dialyses in the medullary raphe. Muscimol increased the diaphragm inspiratory motor output and also increased the amplitude and frequency of abdominal expiratory rhythmic activity during hypercapnia in wakefulness periods. On the other hand, the microdialysis of 8-OH-DPAT attenuated hypercapnia-induced active expiration in a state-dependent manner. Our data suggest that the medullary raphe can either inhibit or potentiate respiratory motor activity during hypercapnia, and the balance of these inhibitory or excitatory outputs may determine the expression of active expiration.
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Affiliation(s)
- Isabela P Leirão
- Department of Physiology and Pathology, School of Dentistry of Araraquara (FOAR), São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Daniel B Zoccal
- Department of Physiology and Pathology, School of Dentistry of Araraquara (FOAR), São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Luciane H Gargaglioni
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University (FCAV-UNESP), Jaboticabal, SP, Brazil
| | - Glauber S F da Silva
- Department of Physiology and Biophysics. Institute of Biological Sciences, Federal University of Minas Gerais (ICB/UFMG), Belo Horizonte, MG, Brazil.
- Departamento de Fisiologia e Biofísica, ICB/UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG, 31270-901, Brazil.
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15
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Biancardi V, Saini J, Pageni A, Prashaad M. H, Funk GD, Pagliardini S. Mapping of the excitatory, inhibitory, and modulatory afferent projections to the anatomically defined active expiratory oscillator in adult male rats. J Comp Neurol 2020; 529:853-884. [DOI: 10.1002/cne.24984] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/29/2020] [Accepted: 07/05/2020] [Indexed: 01/21/2023]
Affiliation(s)
- Vivian Biancardi
- Department of Physiology University of Alberta Edmonton Canada
- Women and Children's Health Research Institute, Faculty of Medicine and Dentistry University of Alberta Edmonton Canada
| | - Jashan Saini
- Department of Physiology University of Alberta Edmonton Canada
| | - Anileen Pageni
- Department of Physiology University of Alberta Edmonton Canada
| | | | - Gregory D. Funk
- Department of Physiology University of Alberta Edmonton Canada
- Women and Children's Health Research Institute, Faculty of Medicine and Dentistry University of Alberta Edmonton Canada
- Neuroscience and Mental Health Institute University of Alberta Edmonton Canada
| | - Silvia Pagliardini
- Department of Physiology University of Alberta Edmonton Canada
- Women and Children's Health Research Institute, Faculty of Medicine and Dentistry University of Alberta Edmonton Canada
- Neuroscience and Mental Health Institute University of Alberta Edmonton Canada
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16
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Flor KC, Barnett WH, Karlen-Amarante M, Molkov YI, Zoccal DB. Inhibitory control of active expiration by the Bötzinger complex in rats. J Physiol 2020; 598:4969-4994. [PMID: 32621515 DOI: 10.1113/jp280243] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 06/21/2020] [Indexed: 12/20/2022] Open
Abstract
KEY POINTS Contraction of abdominal muscles at the end of expiration during metabolic challenges (such as hypercapnia and hypoxia) improves pulmonary ventilation. The emergence of this active expiratory pattern requires the recruitment of the expiratory oscillator located on the ventral surface of the medulla oblongata. Here we show that an inhibitory circuitry located in the Bötzinger complex is an important source of inhibitory drive to the expiratory oscillator. This circuitry, mediated by GABAergic and glycinergic synapses, provides expiratory inhibition that restrains the expiratory oscillator under resting condition and regulates the formation of abdominal expiratory activity during active expiration. By combining experimental and modelling approaches, we propose the organization and connections within the respiratory network that control the changes in the breathing pattern associated with elevated metabolic demand. ABSTRACT The expiratory neurons of the Bötzinger complex (BötC) provide inhibitory inputs to the respiratory network, which, during eupnoea, are critically important for respiratory phase transition and duration control. Here, we investigated how the BötC neurons interact with the expiratory oscillator located in the parafacial respiratory group (pFRG) and control the abdominal activity during active expiration. Using the decerebrated, arterially perfused in situ preparations of juvenile rats, we recorded the activity of expiratory neurons and performed pharmacological manipulations of the BötC and pFRG during hypercapnia or after the exposure to short-term sustained hypoxia - conditions that generate active expiration. The experimental data were integrated in a mathematical model to gain new insights into the inhibitory connectome within the respiratory central pattern generator. Our results indicate that the BötC neurons may establish mutual connections with the pFRG, providing expiratory inhibition during the first stage of expiration and receiving excitatory inputs during late expiration. Moreover, we found that application of GABAergic and glycinergic antagonists in the BötC caused opposing effects on abdominal expiratory activity, suggesting complex inhibitory circuitry within the BötC. Using mathematical modelling, we propose that the BötC network organization and its interactions with the pFRG restrain abdominal activity under resting conditions and contribute to abdominal expiratory pattern formation during active expiration observed during hypercapnia or after the exposure to short-term sustained hypoxia.
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Affiliation(s)
- Karine C Flor
- Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University (UNESP), Araraquara, Brazil
| | - William H Barnett
- Department of Mathematics and Statistics, Georgia State University, Atlanta, GA, USA
| | - Marlusa Karlen-Amarante
- Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University (UNESP), Araraquara, Brazil
| | - Yaroslav I Molkov
- Department of Mathematics and Statistics, Georgia State University, Atlanta, GA, USA.,Neuroscience Institute, Georgia State University, Atlanta, GA, USA
| | - Daniel B Zoccal
- Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University (UNESP), Araraquara, Brazil
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17
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Pisanski A, Ding X, Koch NA, Pagliardini S. Chemogenetic modulation of the parafacial respiratory group influences the recruitment of abdominal activity during REM sleep. Sleep 2020; 43:5634373. [PMID: 31747042 DOI: 10.1093/sleep/zsz283] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 11/01/2019] [Indexed: 12/21/2022] Open
Abstract
Current theories on respiratory control postulate that the respiratory rhythm is generated by oscillatory networks in the medulla: preBötzinger complex (preBötC) is the master oscillator responsible for generating inspiration, while parafacial respiratory group (pFRG) drives active expiration through recruitment of expiratory abdominal (ABD) muscle activity. Research addressing the role of pFRG in ventilation and rhythm generation across sleep states is limited. We recently reported the occurrence of ABD recruitment occurring despite the induction of muscle paralysis during REM sleep. This ABD recruitment was associated with increased tidal volume and regularization of the respiratory period in rats. As pFRG generates active expiration through the engagement of ABD muscles, we hypothesized that the expiratory oscillator is also responsible for the ABD recruitment observed during REM sleep. To test this hypothesis, we inhibited and activated pFRG using chemogenetics (i.e. designer receptors exclusively activated by designer drugs) while recording EEG and respiratory muscle EMG activities across sleep-wake cycles in male Sprague-Dawley rats. Our results suggest that inhibition of pFRG reduced the number of REM events expressing ABD recruitment, in addition to the intensity and prevalence of these events. Conversely, activation of pFRG resulted in an increase in the number of REM events in which ABD recruitment was observed, as well as the intensity and prevalence of ABD recruitment. Interestingly, modulation of pFRG activity did not affect ABD recruitment during NREM sleep or wakefulness. These results suggest that the occurrence of ABD recruitment during sleep is dependent on pFRG activity and is state dependent.
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Affiliation(s)
- Annette Pisanski
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada.,Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Xiuqing Ding
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Nils A Koch
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Silvia Pagliardini
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada.,Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
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18
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Malheiros-Lima MR, Silva JN, Souza FC, Takakura AC, Moreira TS. C1 neurons are part of the circuitry that recruits active expiration in response to the activation of peripheral chemoreceptors. eLife 2020; 9:52572. [PMID: 31971507 PMCID: PMC7010411 DOI: 10.7554/elife.52572] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 01/21/2020] [Indexed: 12/18/2022] Open
Abstract
Breathing results from the interaction of two distinct oscillators: the pre-Bötzinger Complex (preBötC), which drives inspiration; and the lateral parafacial region (pFRG), which drives active expiration. The pFRG is silent at rest and becomes rhythmically active during the stimulation of peripheral chemoreceptors, which also activates adrenergic C1 cells. We postulated that the C1 cells and the pFRG may constitute functionally distinct but interacting populations for controlling expiratory activity during hypoxia. We found in rats that: a) C1 neurons are activated by hypoxia and project to the pFRG region; b) active expiration elicited by hypoxia was blunted after blockade of ionotropic glutamatergic receptors at the level of the pFRG; and c) selective depletion of C1 neurons eliminated the active expiration elicited by hypoxia. These results suggest that C1 cells may regulate the respiratory cycle, including active expiration, under hypoxic conditions.
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Affiliation(s)
- Milene R Malheiros-Lima
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Josiane N Silva
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Felipe C Souza
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Ana C Takakura
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Thiago S Moreira
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil
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19
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de Britto AA, Magalhães KS, da Silva MP, Paton JFR, Moraes DJA. Active expiratory oscillator regulates nasofacial and oral motor activities in rats. Exp Physiol 2020; 105:379-392. [PMID: 31820827 DOI: 10.1113/ep088046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 12/06/2019] [Indexed: 12/11/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does the parafacial respiratory group (pFRG), which mediates active expiration, recruit nasofacial and oral motoneurons to coordinate motor activities that engage muscles controlling airways in rats during active expiration. What is the main finding and its importance? Hypercapnia/acidosis or pFRG activation evoked active expiration and stimulated the motoneurons and nerves responsible for the control of nasofacial and oral airways patency simultaneously. Bilateral pFRG inhibition abolished active expiration and the simultaneous nasofacial and oral motor activities induced by hypercapnia/acidosis. The pFRG is more than a rhythmic oscillator for expiratory pump muscles: it also coordinates nasofacial and oral motor commands that engage muscles controlling airways. ABSTRACT Active expiration is mediated by an expiratory oscillator located in the parafacial respiratory group (pFRG). Active expiration requires more than contracting expiratory muscles as multiple cranial nerves are recruited to stabilize the naso- and oropharyngeal airways. We tested the hypothesis that activation of the pFRG recruits facial and trigeminal motoneurons to coordinate nasofacial and oral motor activities that engage muscles controlling airways in rats during active expiration. Using a combination of electrophysiological and pharmacological approaches, we identified brainstem circuits that phase-lock active expiration, nasofacial and oral motor outputs in an in situ preparation of rat. We found that either high chemical drive (hypercapnia/acidosis) or unilateral excitation (glutamate microinjection) of the pFRG evoked active expiration and stimulated motoneurons (facial and trigeminal) and motor nerves responsible for the control of nasofacial (buccal and zygomatic branches of the facial nerve) and oral (mylohyoid nerve) motor outputs simultaneously. Bilateral pharmacological inhibition (GABAergic and glycinergic receptor activation) of the pFRG abolished active expiration and the simultaneous nasofacial and oral motor activities induced by hypercapnia/acidosis. We conclude that the pFRG provides the excitatory drive to phase-lock rhythmic nasofacial and oral motor circuits during active expiration in rats. Therefore, the pFRG is more than a rhythmic oscillator for expiratory pump muscles: it also coordinates nasofacial and oral motor commands that engage muscles controlling airways in rats during active expiration.
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Affiliation(s)
- Alan A de Britto
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Karolyne S Magalhães
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Melina P da Silva
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Julian F R Paton
- Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, Park Road, Grafton, Auckland, New Zealand
| | - Davi J A Moraes
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
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20
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Furuya WI, Bassi M, Menani JV, Colombari E, Zoccal DB, Colombari DSA. Modulation of hypercapnic respiratory response by cholinergic transmission in the commissural nucleus of the solitary tract. Pflugers Arch 2019; 472:49-60. [PMID: 31884528 DOI: 10.1007/s00424-019-02341-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 11/28/2019] [Accepted: 12/11/2019] [Indexed: 01/16/2023]
Abstract
The nucleus of the solitary tract (NTS) is an important area of the brainstem that receives and integrates afferent cardiorespiratory sensorial information, including those from arterial chemoreceptors and baroreceptors. It was described that acetylcholine (ACh) in the commissural subnucleus of the NTS (cNTS) promotes an increase in the phrenic nerve activity (PNA) and antagonism of nicotinic receptors in the same region reduces the magnitude of tachypneic response to peripheral chemoreceptor stimulation, suggesting a functional role of cholinergic transmission within the cNTS in the chemosensory control of respiratory activity. In the present study, we investigated whether cholinergic receptor antagonism in the cNTS modifies the sympathetic and respiratory reflex responses to hypercapnia. Using an arterially perfused in situ preparation of juvenile male Holtzman rats, we found that the nicotinic antagonist (mecamylamine, 5 mM), but not the muscarinic antagonist (atropine, 5 mM), into the cNTS attenuated the hypercapnia-induced increase of hypoglossal activity. Furthermore, mecamylamine in the cNTS potentiated the generation of late-expiratory (late-E) activity in abdominal nerve induced by hypercapnia. None of the cholinergic antagonists microinjected in the cNTS changed either the sympathetic or the phrenic nerve responses to hypercapnia. Our data provide evidence for the role of cholinergic transmission in the cNTS, acting on nicotinic receptors, modulating the hypoglossal and abdominal responses to hypercapnia.
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Affiliation(s)
- Werner I Furuya
- Department of Physiology and Pathology, School of Dentistry, UNESP - São Paulo State University, Araraquara, SP, Brazil
| | - Mirian Bassi
- Department of Physiology and Pathology, School of Dentistry, UNESP - São Paulo State University, Araraquara, SP, Brazil
| | - José V Menani
- Department of Physiology and Pathology, School of Dentistry, UNESP - São Paulo State University, Araraquara, SP, Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, School of Dentistry, UNESP - São Paulo State University, Araraquara, SP, Brazil
| | - Daniel B Zoccal
- Department of Physiology and Pathology, School of Dentistry, UNESP - São Paulo State University, Araraquara, SP, Brazil
| | - Débora S A Colombari
- Department of Physiology and Pathology, School of Dentistry, UNESP - São Paulo State University, Araraquara, SP, Brazil.
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21
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Silva JN, Oliveira LM, Souza FC, Moreira TS, Takakura AC. Distinct pathways to the parafacial respiratory group to trigger active expiration in adult rats. Am J Physiol Lung Cell Mol Physiol 2019; 317:L402-L413. [DOI: 10.1152/ajplung.00467.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Active expiration (AE) is part of the breathing phase; it is conditional and occurs when we increase our metabolic demand, such as during hypercapnia, hypoxia, or exercise. The parafacial respiratory group (pFRG) is involved in AE. Data from the literature suggest that excitatory and the absence of inhibitory inputs to the pFRG are necessary to determine AE. However, the source of the inputs to the pFRG that trigger AE remains unclear. We show in adult urethane-anesthetized Wistar rats that the pharmacological inhibition of the medial aspect of the nucleus of the solitary tract (mNTS) or the rostral aspect of the pedunculopontine tegmental nucleus (rPPTg) is able to generate AE. In addition, direct inhibitory projection from the mNTS or indirect cholinergic projection from the rPPTg is able to contact pFRG to trigger AE. The inhibition of the mNTS or the rPPTg under conditions of high metabolic demand, such as hypercapnia (9–10% CO2), did not affect the AE. The present results suggest for the first time that inhibitory sources from the mNTS and a cholinergic pathway from the rPPTg, involving M2/M4 muscarinic receptors, could be important sources to modulate and sustain AE.
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Affiliation(s)
- Josiane N. Silva
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo, Sao Paulo, Brazil
| | - Luiz M. Oliveira
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo, Sao Paulo, Brazil
| | - Felipe C. Souza
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo, Sao Paulo, Brazil
| | - Thiago S. Moreira
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of São Paulo, Sao Paulo, Brazil
| | - Ana C. Takakura
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo, Sao Paulo, Brazil
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22
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Bazilio DS, Bonagamba LGH, Moraes DJA, Machado BH. Cardiovascular and respiratory profiles during the sleep-wake cycle of rats previously submitted to chronic intermittent hypoxia. Exp Physiol 2019; 104:1408-1419. [PMID: 31099915 DOI: 10.1113/ep087784] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 05/15/2019] [Indexed: 12/22/2022]
Abstract
NEW FINDINGS What is the central question of this study? Chronic intermittent hypoxia (CIH) causes increased arterial pressure (AP), sympathetic overactivity and changes in expiratory modulation of sympathetic activity. However, changes in the short-term sleep-wake cycle pattern after CIH and their potential impact on cardiorespiratory parameters have not been reported previously. What is the main finding and its importance? Exposure to CIH for 10 days elevates AP in wakefulness and sleep but does not cause major changes in short-term sleep-wake cycle pattern. A higher incidence of muscular expiratory activity was observed in rats exposed to CIH only during wakefulness, indicating that active expiration is not required for the increase in AP in rats submitted to CIH. ABSTRACT Chronic intermittent hypoxia (CIH) increases arterial pressure (AP) and changes sympathetic-respiratory coupling. However, the alterations in the sleep-wake cycle after CIH and their potential impact on cardiorespiratory parameters remain unknown. Here, we evaluated whether CIH-exposed rats present changes in their short-term sleep-wake cycle pattern and in cardiorespiratory parameters. Male Wistar rats (∼250 g) were divided into CIH and control groups. The CIH rats were exposed to 8 h day-1 of cycles of normoxia (fraction of inspired O2 = 0.208, 5 min) followed by hypoxia (fraction of inspired O2 = 0.06, 30-40 s) for 10 days. One day after CIH, electrocorticographic activity, cervical EMG, AP and heart rate were recorded for 3 h. Plethysmographic recordings were collected for 2 h. A subgroup of control and CIH rats also had the diaphragm and oblique abdominal muscle activities recorded. Chronic intermittent hypoxia did not alter the time for sleep onset, total time awake, durations of rapid eye movement (REM) and non-REM (NREM) sleep and number of REM episodes in the 3 h recordings. However, a significant increase in the duration of REM episodes was observed. The AP and heart rate were increased in all phases of the cycle in rats exposed to CIH. Respiratory frequency and ventilation were similar between groups in all phases, but tidal volume was increased during NREM and REM sleep in rats exposed to CIH. An increase in the incidence of active expiration during wakefulness was observed in rats exposed to CIH. The data show that CIH-related hypertension is not caused by changes in the sleep-wake cycle and suggest that active expiration is not required for the increase in AP in freely moving rats exposed to CIH.
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Affiliation(s)
- Darlan S Bazilio
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Leni G H Bonagamba
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Davi J A Moraes
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Benedito H Machado
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
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Magalhães KS, Spiller PF, da Silva MP, Kuntze LB, Paton JFR, Machado BH, Moraes DJA. Locus Coeruleus as a vigilance centre for active inspiration and expiration in rats. Sci Rep 2018; 8:15654. [PMID: 30353035 PMCID: PMC6199338 DOI: 10.1038/s41598-018-34047-w] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 10/08/2018] [Indexed: 01/05/2023] Open
Abstract
At rest, inspiration is an active process while expiration is passive. However, high chemical drive (hypercapnia or hypoxia) activates central and peripheral chemoreceptors triggering reflex increases in inspiration and active expiration. The Locus Coeruleus contains noradrenergic neurons (A6 neurons) that increase their firing frequency when exposed to hypercapnia and hypoxia. Using recently developed neuronal hyperpolarising technology in conscious rats, we tested the hypothesis that A6 neurons are a part of a vigilance centre for controlling breathing under high chemical drive and that this includes recruitment of active inspiration and expiration in readiness for flight or fight. Pharmacogenetic inhibition of A6 neurons was without effect on resting and on peripheral chemoreceptors-evoked inspiratory, expiratory and ventilatory responses. On the other hand, the number of sighs evoked by systemic hypoxia was reduced. In the absence of peripheral chemoreceptors, inhibition of A6 neurons during hypercapnia did not affect sighing, but reduced both the magnitude and incidence of active expiration, and the frequency and amplitude of inspiration. These changes reduced pulmonary ventilation. Our data indicated that A6 neurons exert a CO2-dependent modulation of expiratory drive. The data also demonstrate that A6 neurons contribute to the CO2-evoked increases in the inspiratory motor output and hypoxia-evoked sighing.
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Affiliation(s)
- Karolyne S Magalhães
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Pedro F Spiller
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Melina P da Silva
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Luciana B Kuntze
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Julian F R Paton
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences, University of Bristol, Bristol, UK.,Cardiovascular Autonomic Research Cluster, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Benedito H Machado
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Davi J A Moraes
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil.
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24
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Barnett WH, Jenkin SEM, Milsom WK, Paton JFR, Abdala AP, Molkov YI, Zoccal DB. The Kölliker-Fuse nucleus orchestrates the timing of expiratory abdominal nerve bursting. J Neurophysiol 2017; 119:401-412. [PMID: 29070631 DOI: 10.1152/jn.00499.2017] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Coordination of respiratory pump and valve muscle activity is essential for normal breathing. A hallmark respiratory response to hypercapnia and hypoxia is the emergence of active exhalation, characterized by abdominal muscle pumping during the late one-third of expiration (late-E phase). Late-E abdominal activity during hypercapnia has been attributed to the activation of expiratory neurons located within the parafacial respiratory group (pFRG). However, the mechanisms that control emergence of active exhalation, and its silencing in restful breathing, are not completely understood. We hypothesized that inputs from the Kölliker-Fuse nucleus (KF) control the emergence of late-E activity during hypercapnia. Previously, we reported that reversible inhibition of the KF reduced postinspiratory (post-I) motor output to laryngeal adductor muscles and brought forward the onset of hypercapnia-induced late-E abdominal activity. Here we explored the contribution of the KF for late-E abdominal recruitment during hypercapnia by pharmacologically disinhibiting the KF in in situ decerebrate arterially perfused rat preparations. These data were combined with previous results and incorporated into a computational model of the respiratory central pattern generator. Disinhibition of the KF through local parenchymal microinjections of gabazine (GABAA receptor antagonist) prolonged vagal post-I activity and inhibited late-E abdominal output during hypercapnia. In silico, we reproduced this behavior and predicted a mechanism in which the KF provides excitatory drive to post-I inhibitory neurons, which in turn inhibit late-E neurons of the pFRG. Although the exact mechanism proposed by the model requires testing, our data confirm that the KF modulates the formation of late-E abdominal activity during hypercapnia. NEW & NOTEWORTHY The pons is essential for the formation of the three-phase respiratory pattern, controlling the inspiratory-expiratory phase transition. We provide functional evidence of a novel role for the Kölliker-Fuse nucleus (KF) controlling the emergence of abdominal expiratory bursts during active expiration. A computational model of the respiratory central pattern generator predicts a possible mechanism by which the KF interacts indirectly with the parafacial respiratory group and exerts an inhibitory effect on the expiratory conditional oscillator.
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Affiliation(s)
- William H Barnett
- Department of Mathematics and Statistics, Georgia State University , Atlanta, Georgia
| | - Sarah E M Jenkin
- Department of Zoology, University of British Columbia , Vancouver, British Columbia , Canada
| | - William K Milsom
- Department of Zoology, University of British Columbia , Vancouver, British Columbia , Canada
| | - Julian F R Paton
- School of Physiology, Pharmacology and Neuroscience, Faculty of Biomedical Sciences, University of Bristol , Bristol , United Kingdom.,Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland , Auckland , New Zealand
| | - Ana P Abdala
- School of Physiology, Pharmacology and Neuroscience, Faculty of Biomedical Sciences, University of Bristol , Bristol , United Kingdom
| | - Yaroslav I Molkov
- Department of Mathematics and Statistics, Georgia State University , Atlanta, Georgia.,Neuroscience Institute, Georgia State University , Atlanta, Georgia
| | - Daniel B Zoccal
- Department of Physiology and Pathology, São Paulo State University , Araraquara , Brazil
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Affiliation(s)
- Ken D O'Halloran
- Department of Physiology, School of Medicine, University College Cork, Ireland
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