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Ramirez JM, Carroll MS, Burgraff N, Rand CM, Weese-Mayer DE. A narrative review of the mechanisms and consequences of intermittent hypoxia and the role of advanced analytic techniques in pediatric autonomic disorders. Clin Auton Res 2023; 33:287-300. [PMID: 37326924 DOI: 10.1007/s10286-023-00958-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 05/25/2023] [Indexed: 06/17/2023]
Abstract
Disorders of autonomic functions are typically characterized by disturbances in multiple organ systems. These disturbances are often comorbidities of common and rare diseases, such as epilepsy, sleep apnea, Rett syndrome, congenital heart disease or mitochondrial diseases. Characteristic of many autonomic disorders is the association with intermittent hypoxia and oxidative stress, which can cause or exaggerate a variety of other autonomic dysfunctions, making the treatment and management of these syndromes very complex. In this review we discuss the cellular mechanisms by which intermittent hypoxia can trigger a cascade of molecular, cellular and network events that result in the dysregulation of multiple organ systems. We also describe the importance of computational approaches, artificial intelligence and the analysis of big data to better characterize and recognize the interconnectedness of the various autonomic and non-autonomic symptoms. These techniques can lead to a better understanding of the progression of autonomic disorders, ultimately resulting in better care and management.
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Affiliation(s)
- Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, 1900 Ninth Avenue, Seattle, WA, 98101, USA.
- Departments of Neurological Surgery and Pediatrics, University of Washington School of Medicine, 1900 Ninth Avenue, Seattle, WA, 98101, USA.
| | - Michael S Carroll
- Data Analytics and Reporting, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
- Division of Autonomic Medicine, Stanley Manne Children's Research Institute at Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Nicholas Burgraff
- Center for Integrative Brain Research, Seattle Children's Research Institute, 1900 Ninth Avenue, Seattle, WA, 98101, USA
| | - Casey M Rand
- Division of Autonomic Medicine, Stanley Manne Children's Research Institute at Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Debra E Weese-Mayer
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
- Division of Autonomic Medicine, Stanley Manne Children's Research Institute at Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
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2
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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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3
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Paton JFR, Machado BH, Moraes DJA, Zoccal DB, Abdala AP, Smith JC, Antunes VR, Murphy D, Dutschmann M, Dhingra RR, McAllen R, Pickering AE, Wilson RJA, Day TA, Barioni NO, Allen AM, Menuet C, Donnelly J, Felippe I, St-John WM. Advancing respiratory-cardiovascular physiology with the working heart-brainstem preparation over 25 years. J Physiol 2022; 600:2049-2075. [PMID: 35294064 PMCID: PMC9322470 DOI: 10.1113/jp281953] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 03/04/2022] [Indexed: 11/24/2022] Open
Abstract
Twenty‐five years ago, a new physiological preparation called the working heart–brainstem preparation (WHBP) was introduced with the claim it would provide a new platform allowing studies not possible before in cardiovascular, neuroendocrine, autonomic and respiratory research. Herein, we review some of the progress made with the WHBP, some advantages and disadvantages along with potential future applications, and provide photographs and technical drawings of all the customised equipment used for the preparation. Using mice or rats, the WHBP is an in situ experimental model that is perfused via an extracorporeal circuit benefitting from unprecedented surgical access, mechanical stability of the brain for whole cell recording and an uncompromised use of pharmacological agents akin to in vitro approaches. The preparation has revealed novel mechanistic insights into, for example, the generation of distinct respiratory rhythms, the neurogenesis of sympathetic activity, coupling between respiration and the heart and circulation, hypothalamic and spinal control mechanisms, and peripheral and central chemoreceptor mechanisms. Insights have been gleaned into diseases such as hypertension, heart failure and sleep apnoea. Findings from the in situ preparation have been ratified in conscious in vivo animals and when tested have translated to humans. We conclude by discussing potential future applications of the WHBP including two‐photon imaging of peripheral and central nervous systems and adoption of pharmacogenetic tools that will improve our understanding of physiological mechanisms and reveal novel mechanisms that may guide new treatment strategies for cardiorespiratory diseases.
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Affiliation(s)
- Julian F R Paton
- Manaaki Manawa - The Centre for Heart Research, Faculty of Medical & Health Science, University of Auckland, Park Road, Grafton, Auckland, 1142, New Zealand
| | - Benedito H Machado
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Davi J A Moraes
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Daniel B Zoccal
- Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University, Araraquara, São Paulo, Brazil
| | - Ana P Abdala
- School of Physiology, Pharmacology and Neuroscience, Faculty of Biomedical Sciences, University of Bristol, Bristol, England, BS8 1TD, UK
| | - Jeffrey C Smith
- Cellular and Systems Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Vagner R Antunes
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - David Murphy
- Molecular Neuroendocrinology Research Group, Bristol Medical School: Translational Health Sciences, University of Bristol, Bristol, UK
| | - Mathias Dutschmann
- Florey institute of Neuroscience and Mental Health, University of Melbourne, 30, Royal Parade, Parkville, Victoria, 3052, Australia
| | - Rishi R Dhingra
- Florey institute of Neuroscience and Mental Health, University of Melbourne, 30, Royal Parade, Parkville, Victoria, 3052, Australia
| | - Robin McAllen
- Florey institute of Neuroscience and Mental Health, University of Melbourne, 30, Royal Parade, Parkville, Victoria, 3052, Australia
| | - Anthony E Pickering
- School of Physiology, Pharmacology and Neuroscience, Faculty of Biomedical Sciences, University of Bristol, Bristol, England, BS8 1TD, UK
| | - Richard J A Wilson
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Trevor A Day
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Nicole O Barioni
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Andrew M Allen
- Department of Anatomy & Physiology, The University of Melbourne, Victoria, 3010, Australia
| | - Clément Menuet
- Institut de Neurobiologie de la Méditerranée, INMED UMR1249, INSERM, Aix-Marseille Université, Marseille, France
| | - Joseph Donnelly
- Department of Medicine, Faculty of Medical and Health Sciences, The University of Auckland, New Zealand
| | - Igor Felippe
- Manaaki Manawa - The Centre for Heart Research, Faculty of Medical & Health Science, University of Auckland, Park Road, Grafton, Auckland, 1142, New Zealand
| | - Walter M St-John
- Emeritus Professor, Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Dartmouth, New Hampshire, USA
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4
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Zoccal DB. The nature of sympathetic rhythmicity. J Physiol 2022; 600:2537-2539. [DOI: 10.1113/jp282863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 03/09/2022] [Indexed: 11/08/2022] Open
Affiliation(s)
- Daniel B. Zoccal
- Department of Physiology and Pathology School of Dentistry of Araraquara São Paulo State University
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5
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Abstract
Much of biology is rhythmical and comprises oscillators that can couple. These have optimized energy efficiency and have been preserved during evolution. The respiratory and cardiovascular systems contain numerous oscillators, and importantly, they couple. This coupling is dynamic but essential for an efficient transmission of neural information critical for the precise linking of breathing and oxygen delivery while permitting adaptive responses to changes in state. The respiratory pattern generator and the neural network responsible for sympathetic and cardiovagal (parasympathetic) tone generation interact at many levels ensuring that cardiac output and regional blood flow match oxygen delivery to the lungs and tissues efficiently. The most classic manifestations of these interactions are respiratory sinus arrhythmia and the respiratory modulation of sympathetic nerve activity. These interactions derive from shared somatic and cardiopulmonary afferent inputs, reciprocal interactions between brainstem networks and inputs from supra-pontine regions. Disrupted respiratory-cardiovascular coupling can result in disease, where it may further the pathophysiological sequelae and be a harbinger of poor outcomes. This has been well documented by diminished respiratory sinus arrhythmia and altered respiratory sympathetic coupling in animal models and/or patients with myocardial infarction, heart failure, diabetes mellitus, and neurological disorders as stroke, brain trauma, Parkinson disease, or epilepsy. Future research needs to assess the therapeutic potential for ameliorating respiratory-cardiovascular coupling in disease.
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Affiliation(s)
- James P Fisher
- Manaaki Manawa-The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, Auckland, New Zealand
| | - Tymoteusz Zera
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Warsaw, Poland
| | - Julian F R Paton
- Manaaki Manawa-The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, Auckland, New Zealand.
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6
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Guyenet PG, Stornetta RL. Rostral ventrolateral medulla, retropontine region and autonomic regulations. Auton Neurosci 2021; 237:102922. [PMID: 34814098 DOI: 10.1016/j.autneu.2021.102922] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 11/08/2021] [Accepted: 11/15/2021] [Indexed: 12/17/2022]
Abstract
The rostral half of the ventrolateral medulla (RVLM) and adjacent ventrolateral retropontine region (henceforth RVLMRP) have been divided into various sectors by neuroscientists interested in breathing or autonomic regulations. The RVLMRP regulates respiration, glycemia, vigilance and inflammation, in addition to blood pressure. It contains interoceptors that respond to acidification, hypoxia and intracranial pressure and its rostral end contains the retrotrapezoid nucleus (RTN) which is the main central respiratory chemoreceptor. Acid detection by the RTN is an intrinsic property of the principal neurons that is enhanced by paracrine influences from surrounding astrocytes and CO2-dependent vascular constriction. RTN mediates the hypercapnic ventilatory response via complex projections to the respiratory pattern generator (CPG). The RVLM contributes to autonomic response patterns via differential recruitment of several subtypes of adrenergic (C1) and non-adrenergic neurons that directly innervate sympathetic and parasympathetic preganglionic neurons. The RVLM also innervates many brainstem and hypothalamic nuclei that contribute, albeit less directly, to autonomic responses. All lower brainstem noradrenergic clusters including the locus coeruleus are among these targets. Sympathetic tone to the circulatory system is regulated by subsets of presympathetic RVLM neurons whose activity is continuously restrained by the baroreceptors and modulated by the respiratory CPG. The inhibitory input from baroreceptors and the excitatory input from the respiratory CPG originate from neurons located in or close to the rhythm generating region of the respiratory CPG (preBötzinger complex).
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Affiliation(s)
- Patrice G Guyenet
- University of Virginia School of Medicine, Department of Pharmacology, 1340 Jefferson Park Avenue, Charlottesville, VA 22908-0735, USA.
| | - Ruth L Stornetta
- University of Virginia School of Medicine, Department of Pharmacology, 1340 Jefferson Park Avenue, Charlottesville, VA 22908-0735, USA.
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7
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Peng YJ, Su X, Wang B, Matthews T, Nanduri J, Prabhakar NR. Role of olfactory receptor78 in carotid body-dependent sympathetic activation and hypertension in murine models of chronic intermittent hypoxia. J Neurophysiol 2021; 125:2054-2067. [PMID: 33909496 DOI: 10.1152/jn.00067.2021] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic intermittent hypoxia (CIH) is a hallmark manifestation of obstructive sleep apnea (OSA), a widespread breathing disorder. CIH-treated rodents exhibit activation of the sympathetic nervous system and hypertension. Heightened carotid body (CB) activity has been implicated in CIH-induced hypertension. CB expresses high abundance of olfactory receptor (Olfr) 78, a G-protein coupled receptor. Olfr 78 null mice exhibit impaired CB sensory nerve response to acute hypoxia. Present study examined whether Olfr78 participates in CB-dependent activation of the sympathetic nervous system and hypertension in CIH-treated mice and in hemeoxygenase (HO)-2 null mice experiencing CIH as a consequence of naturally occurring OSA. CIH-treated wild-type (WT) mice showed hypertension, biomarkers of sympathetic nerve activation, and enhanced CB sensory nerve response to hypoxia and sensory long-term facilitation (sLTF), and these responses were absent in CIH-treated Olfr78 null mice. HO-2 null mice showed higher apnea index (AI) (58 ± 1.2 apneas/h) than WT mice (AI = 8 ± 0.8 apneas/h) and exhibited elevated blood pressure (BP), elevated plasma norepinephrine (NE) levels, and heightened CB sensory nerve response to hypoxia and sLTF. The magnitude of hypertension correlated with AI in HO-2 null mice. In contrast, HO-2/Olfr78 double null mice showed absence of elevated BP and plasma NE levels and augmented CB response to hypoxia and sLTF. These results demonstrate that Olfr78 participates in sympathetic nerve activation and hypertension and heightened CB activity in two murine models of CIH.NEW & NOTEWORTHY Carotid body (CB) sensory nerve activation is essential for sympathetic nerve excitation and hypertension in rodents treated with chronic intermittent hypoxia (CIH) simulating blood O2 profiles during obstructive sleep apnea (OSA). Here, we report that CIH-treated mice and hemeoxygenase (HO)-2-deficient mice, which show OSA phenotype, exhibit sympathetic excitation, hypertension, and CB activation. These effects are absent in Olfr78 null and Olfr78/HO-2 double null mice.
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Affiliation(s)
- Ying-Jie Peng
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, University of Chicago, Chicago, Illinois
| | - Xiaoyu Su
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, University of Chicago, Chicago, Illinois
| | - Benjamin Wang
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, University of Chicago, Chicago, Illinois
| | - Timothy Matthews
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, University of Chicago, Chicago, Illinois
| | - Jayasri Nanduri
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, University of Chicago, Chicago, Illinois
| | - Nanduri R Prabhakar
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, University of Chicago, Chicago, Illinois
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8
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Guyenet PG, Stornetta RL, Souza GMPR, Abbott SBG, Brooks VL. Neuronal Networks in Hypertension: Recent Advances. Hypertension 2020; 76:300-311. [PMID: 32594802 DOI: 10.1161/hypertensionaha.120.14521] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neurogenic hypertension is associated with excessive sympathetic nerve activity to the kidneys and portions of the cardiovascular system. Here we examine the brain regions that cause heightened sympathetic nerve activity in animal models of neurogenic hypertension, and we discuss the triggers responsible for the changes in neuronal activity within these regions. We highlight the limitations of the evidence and, whenever possible, we briefly address the pertinence of the findings to human hypertension. The arterial baroreflex reduces arterial blood pressure variability and contributes to the arterial blood pressure set point. This set point can also be elevated by a newly described cerebral blood flow-dependent and astrocyte-mediated sympathetic reflex. Both reflexes converge on the presympathetic neurons of the rostral medulla oblongata, and both are plausible causes of neurogenic hypertension. Sensory afferent dysfunction (reduced baroreceptor activity, increased renal, or carotid body afferent) contributes to many forms of neurogenic hypertension. Neurogenic hypertension can also result from activation of brain nuclei or sensory afferents by excess circulating hormones (leptin, insulin, Ang II [angiotensin II]) or sodium. Leptin raises blood vessel sympathetic nerve activity by activating the carotid bodies and subsets of arcuate neurons. Ang II works in the lamina terminalis and probably throughout the brain stem and hypothalamus. Sodium is sensed primarily in the lamina terminalis. Regardless of its cause, the excess sympathetic nerve activity is mediated to some extent by activation of presympathetic neurons located in the rostral ventrolateral medulla or the paraventricular nucleus of the hypothalamus. Increased activity of the orexinergic neurons also contributes to hypertension in selected models.
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Affiliation(s)
- Patrice G Guyenet
- From the Department of Pharmacology, University of Virginia, Charlottesville (P.G.G., R.L.S., G.M.P.R.S., S.B.G.A.)
| | - Ruth L Stornetta
- From the Department of Pharmacology, University of Virginia, Charlottesville (P.G.G., R.L.S., G.M.P.R.S., S.B.G.A.)
| | - George M P R Souza
- From the Department of Pharmacology, University of Virginia, Charlottesville (P.G.G., R.L.S., G.M.P.R.S., S.B.G.A.)
| | - Stephen B G Abbott
- From the Department of Pharmacology, University of Virginia, Charlottesville (P.G.G., R.L.S., G.M.P.R.S., S.B.G.A.)
| | - Virginia L Brooks
- Department of Chemical Physiology and Biochemistry, Oregon Health & Sciences University, Portland (V.L.B.)
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9
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Menuet C, Connelly AA, Bassi JK, Melo MR, Le S, Kamar J, Kumar NN, McDougall SJ, McMullan S, Allen AM. PreBötzinger complex neurons drive respiratory modulation of blood pressure and heart rate. eLife 2020; 9:57288. [PMID: 32538785 PMCID: PMC7326498 DOI: 10.7554/elife.57288] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 06/14/2020] [Indexed: 12/14/2022] Open
Abstract
Heart rate and blood pressure oscillate in phase with respiratory activity. A component of these oscillations is generated centrally, with respiratory neurons entraining the activity of pre-sympathetic and parasympathetic cardiovascular neurons. Using a combination of optogenetic inhibition and excitation in vivo and in situ in rats, as well as neuronal tracing, we demonstrate that preBötzinger Complex (preBötC) neurons, which form the kernel for inspiratory rhythm generation, directly modulate cardiovascular activity. Specifically, inhibitory preBötC neurons modulate cardiac parasympathetic neuron activity whilst excitatory preBötC neurons modulate sympathetic vasomotor neuron activity, generating heart rate and blood pressure oscillations in phase with respiration. Our data reveal yet more functions entrained to the activity of the preBötC, with a role in generating cardiorespiratory oscillations. The findings have implications for cardiovascular pathologies, such as hypertension and heart failure, where respiratory entrainment of heart rate is diminished and respiratory entrainment of blood pressure exaggerated.
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Affiliation(s)
- Clément Menuet
- Department of Physiology, University of Melbourne, Victoria, Australia.,Institut de Neurobiologie de la Méditerranée, INMED UMR1249, INSERM, Aix-Marseille Université, Marseille, France
| | - Angela A Connelly
- Department of Physiology, University of Melbourne, Victoria, Australia
| | - Jaspreet K Bassi
- Department of Physiology, University of Melbourne, Victoria, Australia
| | - Mariana R Melo
- Department of Physiology, University of Melbourne, Victoria, Australia
| | - Sheng Le
- Faculty of Medicine & Health Sciences, Macquarie University, NSW, Australia
| | - Jessica Kamar
- Department of Physiology, University of Melbourne, Victoria, Australia
| | - Natasha N Kumar
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, NSW, Australia
| | - Stuart J McDougall
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
| | - Simon McMullan
- Faculty of Medicine & Health Sciences, Macquarie University, NSW, Australia
| | - Andrew M Allen
- Department of Physiology, University of Melbourne, Victoria, Australia.,Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
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10
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Magalhães KS, de Britto AA, Paton JFR, Moraes DJA. A6 neurons simultaneously modulate active expiration and upper airway resistance in rats. Exp Physiol 2019; 105:53-64. [PMID: 31675759 DOI: 10.1113/ep088164] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 10/23/2019] [Indexed: 12/30/2022]
Abstract
NEW FINDINGS What is the central question of this study? Do A6 neurons modulate active expiratory and airway responses evoked by hypercapnia/acidosis? What is the main finding and its importance? Acute inhibition of A6 neurons reduced active expiratory, inspiratory and the associated oropharyngeal and laryngeal motor responses to hypercapnia/acidosis. A6 neurons provide excitatory synaptic drive contributing to the central generation of inspiratory and expiratory motor activity as well as the control of upper airway resistance. ABSTRACT During rest, inspiration is an active phenomenon, whereas expiration is passive. Under conditions of high chemical drive, such as hypercapnia/acidosis, there is an increase in inspiratory activity, expiration becomes active and upper airway resistance is reduced. The locus coeruleus noradrenergic neurons (A6 neurons) are activated when exposed to elevated CO2 /[H+ ] levels and modulate respiratory brainstem neurons regulating ventilation. However, the role of A6 neurons in the control of upper airway resistance is not fully understood. We tested the hypothesis that A6 neurons contribute to the central generation of active inspiratory and expiratory responses and the associated changes in the motor nerves controlling upper airway resistance during hypercapnia/acidosis in rats. Using a perfused brainstem-spinal cord preparation, we inhibited A6 neurons using pharmacogenetics and evaluated the active expiratory (abdominal nerve), laryngeal (cervical vagus nerve), oropharyngeal (hypoglossal nerve) and inspiratory (phrenic nerve) motor nerve responses to hypercapnia/acidosis. Acute inhibition of A6 neurons did not produce significant changes in the respiratory pattern in normocapnia. However, the hypercapnia/acidosis-induced active expiratory response and the associated changes in the motor nerves responsible for control of oropharyngeal and laryngeal resistance, as well as the inspiratory response were all reduced after inhibition of A6 neurons. Our data demonstrate that A6 neurons exert an important excitatory synaptic drive to the central generation of both active inspiratory and expiratory activities and modulate the control of upper airway resistance during hypercapnia/acidosis.
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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
| | - Alan A de Britto
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Julian F R Paton
- Cardiovascular Autonomic Research Cluster, 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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11
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Integration of hindbrain and carotid body mechanisms that control the autonomic response to cardiorespiratory and glucoprivic insults. Respir Physiol Neurobiol 2019; 265:83-91. [DOI: 10.1016/j.resp.2018.08.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 08/01/2018] [Accepted: 08/29/2018] [Indexed: 01/08/2023]
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12
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Lindsey BG, Nuding SC, Segers LS, Morris KF. Carotid Bodies and the Integrated Cardiorespiratory Response to Hypoxia. Physiology (Bethesda) 2019; 33:281-297. [PMID: 29897299 DOI: 10.1152/physiol.00014.2018] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Advances in our understanding of brain mechanisms for the hypoxic ventilatory response, coordinated changes in blood pressure, and the long-term consequences of chronic intermittent hypoxia as in sleep apnea, such as hypertension and heart failure, are giving impetus to the search for therapies to "erase" dysfunctional memories distributed in the carotid bodies and central nervous system. We review current network models, open questions, sex differences, and implications for translational research.
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Affiliation(s)
- Bruce G Lindsey
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida , Tampa, Florida
| | - Sarah C Nuding
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida , Tampa, Florida
| | - Lauren S Segers
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida , Tampa, Florida
| | - Kendall F Morris
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida , Tampa, Florida
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13
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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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14
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Zoccal DB, Silva JN, Barnett WH, Lemes EV, Falquetto B, Colombari E, Molkov YI, Moreira TS, Takakura AC. Interaction between the retrotrapezoid nucleus and the parafacial respiratory group to regulate active expiration and sympathetic activity in rats. Am J Physiol Lung Cell Mol Physiol 2018; 315:L891-L909. [PMID: 30188747 DOI: 10.1152/ajplung.00011.2018] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The retrotrapezoid nucleus (RTN) contains chemosensitive cells that distribute CO2-dependent excitatory drive to the respiratory network. This drive facilitates the function of the respiratory central pattern generator (rCPG) and increases sympathetic activity. It is also evidenced that during hypercapnia, the late-expiratory (late-E) oscillator in the parafacial respiratory group (pFRG) is activated and determines the emergence of active expiration. However, it remains unclear the microcircuitry responsible for the distribution of the excitatory signals to the pFRG and the rCPG in conditions of high CO2. Herein, we hypothesized that excitatory inputs from chemosensitive neurons in the RTN are necessary for the activation of late-E neurons in the pFRG. Using the decerebrated in situ rat preparation, we found that lesions of neurokinin-1 receptor-expressing neurons in the RTN region with substance P-saporin conjugate suppressed the late-E activity in abdominal nerves (AbNs) and sympathetic nerves (SNs) and attenuated the increase in phrenic nerve (PN) activity induced by hypercapnia. On the other hand, kynurenic acid (100 mM) injections in the pFRG eliminated the late-E activity in AbN and thoracic SN but did not modify PN response during hypercapnia. Iontophoretic injections of retrograde tracer into the pFRG of adult rats revealed labeled phox2b-expressing neurons within the RTN. Our findings are supported by mathematical modeling of chemosensitive and late-E populations within the RTN and pFRG regions as two separate but interacting populations in a way that the activation of the pFRG late-E neurons during hypercapnia require glutamatergic inputs from the RTN neurons that intrinsically detect changes in CO2/pH.
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Affiliation(s)
- Daniel B Zoccal
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University , São Paulo , Brazil
| | - Josiane N Silva
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo , São Paulo , Brazil
| | - William H Barnett
- Deptartment of Mathematics and Statistics, Georgia State University , Atlanta, Georgia
| | - Eduardo V Lemes
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University , São Paulo , Brazil
| | - Barbara Falquetto
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo , São Paulo , Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University , São Paulo , Brazil
| | - Yaroslav I Molkov
- Deptartment of Mathematics and Statistics, Georgia State University , Atlanta, Georgia.,Neuroscience Institute, Georgia State University , Atlanta, Georgia
| | - Thiago S Moreira
- Department of Physiology and Biophysics, 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
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