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Nanayakkara B, McNamara S. Pathophysiology of Chronic Hypercapnic Respiratory Failure. Sleep Med Clin 2024; 19:379-389. [PMID: 39095137 DOI: 10.1016/j.jsmc.2024.04.001] [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] [Indexed: 08/04/2024]
Abstract
Chronic hypercapnic respiratory failure occurs in several conditions associated with hypoventilation. The mechanisms underlying the development of chronic hypercapnia include a combination of processes that increase metabolic CO2 production, reduce minute ventilation (V'e), or increase dead space fraction (Vd/Vt). Fundamental to the pathophysiology is a mismatch between increased load and a reduction in the capacity of the respiratory pump to compensate. Though neural respiratory drive may be decreased in a subset of central hypoventilation disorders, it is more commonly increased in attempting to maintain the load-capacity homeostatic balance.
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Affiliation(s)
- Budhima Nanayakkara
- Charles Sturt University, 346 Leeds Parade, Orange, NSW 2800, Australia; Department of Medicine, Orange Health Service, Orange, NSW 2800, Australia; University of Sydney, Camperdown, NSW 2006, Australia.
| | - Stephen McNamara
- Department of Respiratory & Sleep Medicine, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia
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2
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Aung O, Amorim MR, Mendelowitz D, Polotsky VY. Revisiting the Role of Serotonin in Sleep-Disordered Breathing. Int J Mol Sci 2024; 25:1483. [PMID: 38338762 PMCID: PMC10855456 DOI: 10.3390/ijms25031483] [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: 12/12/2023] [Revised: 01/22/2024] [Accepted: 01/24/2024] [Indexed: 02/12/2024] Open
Abstract
Serotonin or 5-hydroxytryptamine (5-HT) is a ubiquitous neuro-modulator-transmitter that acts in the central nervous system, playing a major role in the control of breathing and other physiological functions. The midbrain, pons, and medulla regions contain several serotonergic nuclei with distinct physiological roles, including regulating the hypercapnic ventilatory response, upper airway patency, and sleep-wake states. Obesity is a major risk factor in the development of sleep-disordered breathing (SDB), such as obstructive sleep apnea (OSA), recurrent closure of the upper airway during sleep, and obesity hypoventilation syndrome (OHS), a condition characterized by daytime hypercapnia and hypoventilation during sleep. Approximately 936 million adults have OSA, and 32 million have OHS worldwide. 5-HT acts on 5-HT receptor subtypes that modulate neural control of breathing and upper airway patency. This article reviews the role of 5-HT in SDB and the current advances in 5-HT-targeted treatments for SDB.
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Affiliation(s)
- O Aung
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA; (O.A.); (M.R.A.)
- Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Anesthesiology and Critical Care Medicine, George Washington University, Washington, DC 20037, USA
| | - Mateus R. Amorim
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA; (O.A.); (M.R.A.)
- Department of Anesthesiology and Critical Care Medicine, George Washington University, Washington, DC 20037, USA
| | - David Mendelowitz
- Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA;
| | - Vsevolod Y. Polotsky
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA; (O.A.); (M.R.A.)
- Department of Anesthesiology and Critical Care Medicine, George Washington University, Washington, DC 20037, USA
- Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA;
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3
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Amorim MR, Wang X, Aung O, Bevans-Fonti S, Anokye-Danso F, Ribeiro C, Escobar J, Freire C, Pho H, Dergacheva O, Branco LGS, Ahima RS, Mendelowitz D, Polotsky VY. Leptin signaling in the dorsomedial hypothalamus couples breathing and metabolism in obesity. Cell Rep 2023; 42:113512. [PMID: 38039129 PMCID: PMC10804286 DOI: 10.1016/j.celrep.2023.113512] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 10/25/2023] [Accepted: 11/14/2023] [Indexed: 12/03/2023] Open
Abstract
Mismatch between CO2 production (Vco2) and respiration underlies the pathogenesis of obesity hypoventilation. Leptin-mediated CNS pathways stimulate both metabolism and breathing, but interactions between these functions remain elusive. We hypothesized that LEPRb+ neurons of the dorsomedial hypothalamus (DMH) regulate metabolism and breathing in obesity. In diet-induced obese LeprbCre mice, chemogenetic activation of LEPRb+ DMH neurons increases minute ventilation (Ve) during sleep, the hypercapnic ventilatory response, Vco2, and Ve/Vco2, indicating that breathing is stimulated out of proportion to metabolism. The effects of chemogenetic activation are abolished by a serotonin blocker. Optogenetic stimulation of the LEPRb+ DMH neurons evokes excitatory postsynaptic currents in downstream serotonergic neurons of the dorsal raphe (DR). Administration of retrograde AAV harboring Cre-dependent caspase to the DR deletes LEPRb+ DMH neurons and abolishes metabolic and respiratory responses to leptin. These findings indicate that LEPRb+ DMH neurons match breathing to metabolism through serotonergic pathways to prevent obesity-induced hypoventilation.
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Affiliation(s)
- Mateus R Amorim
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA; Department of Anesthesiology and Critical Care Medicine, George Washington University, Washington, DC 20037, USA.
| | - Xin Wang
- Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA
| | - O Aung
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA
| | - Shannon Bevans-Fonti
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA; Department of Anesthesiology and Critical Care Medicine, George Washington University, Washington, DC 20037, USA
| | | | - Caitlin Ribeiro
- Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA
| | - Joan Escobar
- Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA
| | - Carla Freire
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA
| | - Huy Pho
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA
| | - Olga Dergacheva
- Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA
| | - Luiz G S Branco
- University of São Paulo, Ribeirão Preto, São Paulo 14040-904, Brazil
| | - Rexford S Ahima
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA
| | - David Mendelowitz
- Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA
| | - Vsevolod Y Polotsky
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA; Department of Anesthesiology and Critical Care Medicine, George Washington University, Washington, DC 20037, USA; Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA.
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4
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Lusk S, Ward CS, Chang A, Twitchell-Heyne A, Fattig S, Allen G, Jankowsky J, Ray R. An automated respiratory data pipeline for waveform characteristic analysis. J Physiol 2023; 601:4767-4806. [PMID: 37786382 PMCID: PMC10841337 DOI: 10.1113/jp284363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 08/11/2023] [Indexed: 10/04/2023] Open
Abstract
Comprehensive and accurate analysis of respiratory and metabolic data is crucial to modelling congenital, pathogenic and degenerative diseases converging on autonomic control failure. A lack of tools for high-throughput analysis of respiratory datasets remains a major challenge. We present Breathe Easy, a novel open-source pipeline for processing raw recordings and associated metadata into operative outcomes, publication-worthy graphs and robust statistical analyses including QQ and residual plots for assumption queries and data transformations. This pipeline uses a facile graphical user interface for uploading data files, setting waveform feature thresholds and defining experimental variables. Breathe Easy was validated against manual selection by experts, which represents the current standard in the field. We demonstrate Breathe Easy's utility by examining a 2-year longitudinal study of an Alzheimer's disease mouse model to assess contributions of forebrain pathology in disordered breathing. Whole body plethysmography has become an important experimental outcome measure for a variety of diseases with primary and secondary respiratory indications. Respiratory dysfunction, while not an initial symptom in many of these disorders, often drives disability or death in patient outcomes. Breathe Easy provides an open-source respiratory analysis tool for all respiratory datasets and represents a necessary improvement upon current analytical methods in the field. KEY POINTS: Respiratory dysfunction is a common endpoint for disability and mortality in many disorders throughout life. Whole body plethysmography in rodents represents a high face-value method for measuring respiratory outcomes in rodent models of these diseases and disorders. Analysis of key respiratory variables remains hindered by manual annotation and analysis that leads to low throughput results that often exclude a majority of the recorded data. Here we present a software suite, Breathe Easy, that automates the process of data selection from raw recordings derived from plethysmography experiments and the analysis of these data into operative outcomes and publication-worthy graphs with statistics. We validate Breathe Easy with a terabyte-scale Alzheimer's dataset that examines the effects of forebrain pathology on respiratory function over 2 years of degeneration.
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Affiliation(s)
- Savannah Lusk
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Christopher S. Ward
- Department of Integrative Physiology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Andersen Chang
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Shaun Fattig
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Genevera Allen
- Departments of Electrical and Computer Engineering, Statistics, and Computer Science, Rice University, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX 77030, USA
| | - Joanna Jankowsky
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
- Departments of Neurology, Neurosurgery, and Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Russell Ray
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
- McNair Medical Institute, Houston, TX 77030, USA
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Tamir-Hostovsky L, Ivanovska J, Parajón E, Patel R, Wang H, Biouss G, Ivanovski N, Belik J, Pierro A, Montandon G, Gauda EB. Maturational effect of leptin on CO 2 chemosensitivity in newborn rats. Pediatr Res 2023; 94:971-978. [PMID: 37185965 DOI: 10.1038/s41390-023-02604-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 03/28/2023] [Accepted: 04/01/2023] [Indexed: 05/17/2023]
Abstract
BACKGROUND Leptin augments central CO2 chemosensitivity and stabilizes breathing in adults. Premature infants have unstable breathing and low leptin levels. Leptin receptors are on CO2 sensitive neurons in the Nucleus Tractus Solitarius (NTS) and locus coeruleus (LC). We hypothesized that exogenous leptin improves hypercapnic respiratory response in newborn rats by improving central CO2 chemosensitivity. METHODS In rats at postnatal day (p)4 and p21, hyperoxic and hypercapnic ventilatory responses, and pSTAT and SOCS3 protein expression in the hypothalamus, NTS and LC were measured before and after treatment with exogenous leptin (6 µg/g). RESULTS Exogenous leptin increased the hypercapnic response in p21 but not in p4 rats (P ≤ 0.001). At p4, leptin increased pSTAT expression only in the LC, and SOCS3 expression in the NTS and LC; while at p21 pSTAT and SOCS3 levels were higher in the hypothalamus, NTS, and LC (P ≤ 0.05). CONCLUSIONS We describe the developmental profile of the effect of exogenous leptin on CO2 chemosensitivity. Exogenous leptin does not augment central CO2 sensitivity during the first week of life in newborn rats. The translational implication of these findings is that low plasma leptin levels in premature infants may not be contributing to respiratory instability. IMPACT Exogenous leptin does not augment CO2 sensitivity during the first week of life in newborn rats, similar to the developmental period when feeding behavior is resistant to leptin. Exogenous leptin increases CO2 chemosensitivity in newborn rats after the 3rd week of life and upregulates the expression of pSTAT and SOC3 in the hypothalamus, NTS and LC. Low plasma leptin levels in premature infants are unlikely contributors to respiratory instability via decreased CO2 sensitivity in premature infants. Thus, it is highly unlikely that exogenous leptin would alter this response.
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Affiliation(s)
- Liran Tamir-Hostovsky
- Division of Neonatology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
| | - Julijana Ivanovska
- Division of Neonatology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
- Translational Program, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Eleana Parajón
- Cellular and Molecular Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Rachana Patel
- Division of Neonatology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Huanhuan Wang
- Division of Neonatology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - George Biouss
- Division of General and Thoracic Surgery, Developmental and Stem Cell Biology Program, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Nikola Ivanovski
- Division of Neonatology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
- Translational Program, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Jaques Belik
- Division of Neonatology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
- Translational Program, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Agostino Pierro
- Division of General and Thoracic Surgery, Developmental and Stem Cell Biology Program, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Gaspard Montandon
- Keenan Research Centre for Biomedical Sciences, St. Michael's Hospital, Unity Health Toronto, University of Toronto, Toronto, ON, Canada
| | - Estelle B Gauda
- Division of Neonatology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
- Translational Program, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
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Sands SA, Alex RM, Mann D, Vena D, Terrill PI, Gell LK, Zinchuk A, Sofer T, Patel SR, Taranto-Montemurro L, Azarbarzin A, Rueschman M, White DP, Wellman A, Redline S. Pathophysiology Underlying Demographic and Obesity Determinants of Sleep Apnea Severity. Ann Am Thorac Soc 2023; 20:440-449. [PMID: 36287615 PMCID: PMC9993145 DOI: 10.1513/annalsats.202203-271oc] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 10/14/2022] [Indexed: 11/20/2022] Open
Abstract
Rationale: Sleep apnea is the manifestation of key endotypic traits, including greater pharyngeal collapsibility, reduced dilator muscle compensation, and elevated chemoreflex loop gain. Objectives: We investigated how endotypic traits vary with obesity, age, sex, and race/ethnicity to influence sleep apnea disease severity (apnea-hypopnea index [AHI]). Methods: Endotypic traits were estimated from polysomnography in a diverse community-based cohort study (Multi-Ethnic Study of Atherosclerosis, N = 1,971; age range, 54-93 yr). Regression models assessed associations between each exposure (continuous variables per 2 standard deviations [SDs]) and endotypic traits (per SD) or AHI (events/h), independent of other exposures. Generalizability was assessed in two independent cohorts. Results: Greater AHI was associated with obesity (+19 events/h per 11 kg/m2 [2 SD]), male sex (+13 events/h vs. female), older age (+7 events/h per 20 yr), and Chinese ancestry (+5 events/h vs. White, obesity adjusted). Obesity-related increase in AHI was best explained by elevated collapsibility (+0.40 SD) and greater loop gain (+0.38 SD; percentage mediated, 26% [95% confidence interval (CI), 20-32%]). Male-related increase in AHI was explained by elevated collapsibility (+0.86 SD) and reduced compensation (-0.40 SD; percentage mediated, 57% [95% CI, 50-66%]). Age-related AHI increase was explained by elevated collapsibility (+0.37 SD) and greater loop gain (+0.15 SD; percentage mediated, 48% [95% CI, 34-63%]). Increased AHI with Chinese ancestry was explained by collapsibility (+0.57 SD; percentage mediated, 87% [95% CI, 57-100]). Black race was associated with reduced collapsibility (-0.30 SD) and elevated loop gain (+0.29 SD). Similar patterns were observed in the other cohorts. Conclusions: Different subgroups exhibit different underlying pathophysiological pathways to sleep apnea, highlighting the variability in mechanisms that could be targeted for intervention.
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Affiliation(s)
- Scott A. Sands
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Raichel M. Alex
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Dwayne Mann
- Institute for Social Science Research and
- School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, Queensland, Australia
| | - Daniel Vena
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Philip I. Terrill
- School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, Queensland, Australia
| | - Laura K. Gell
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Andrey Zinchuk
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Tamar Sofer
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Sanjay R. Patel
- Department of Medicine, Center for Sleep and Cardiovascular Outcomes Research, and
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Luigi Taranto-Montemurro
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Ali Azarbarzin
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Michael Rueschman
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - David P. White
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Andrew Wellman
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Susan Redline
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
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7
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Amorim MR, Aung O, Mokhlesi B, Polotsky VY. Leptin-mediated neural targets in obesity hypoventilation syndrome. Sleep 2022; 45:zsac153. [PMID: 35778900 PMCID: PMC9453616 DOI: 10.1093/sleep/zsac153] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 06/20/2022] [Indexed: 07/30/2023] Open
Abstract
Obesity hypoventilation syndrome (OHS) is defined as daytime hypercapnia in obese individuals in the absence of other underlying causes. In the United States, OHS is present in 10%-20% of obese patients with obstructive sleep apnea and is linked to hypoventilation during sleep. OHS leads to high cardiorespiratory morbidity and mortality, and there is no effective pharmacotherapy. The depressed hypercapnic ventilatory response plays a key role in OHS. The pathogenesis of OHS has been linked to resistance to an adipocyte-produced hormone, leptin, a major regulator of metabolism and control of breathing. Mechanisms by which leptin modulates the control of breathing are potential targets for novel therapeutic strategies in OHS. Recent advances shed light on the molecular pathways related to the central chemoreceptor function in health and disease. Leptin signaling in the nucleus of the solitary tract, retrotrapezoid nucleus, hypoglossal nucleus, and dorsomedial hypothalamus, and anatomical projections from these nuclei to the respiratory control centers, may contribute to OHS. In this review, we describe current views on leptin-mediated mechanisms that regulate breathing and CO2 homeostasis with a focus on potential therapeutics for the treatment of OHS.
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Affiliation(s)
- Mateus R Amorim
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - O Aung
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Babak Mokhlesi
- Department of Internal Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, Rush University Medical Center, Chicago, IL, USA
| | - Vsevolod Y Polotsky
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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8
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Mouradian GC, Liu P, Nakagawa P, Duffy E, Gomez Vargas J, Balapattabi K, Grobe JL, Sigmund CD, Hodges MR. Patch-to-Seq and Transcriptomic Analyses Yield Molecular Markers of Functionally Distinct Brainstem Serotonin Neurons. Front Synaptic Neurosci 2022; 14:910820. [PMID: 35844900 PMCID: PMC9280690 DOI: 10.3389/fnsyn.2022.910820] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 05/10/2022] [Indexed: 01/22/2023] Open
Abstract
Acute regulation of CO2 and pH homeostasis requires sensory feedback from peripheral (carotid body) and central (central) CO2/pH sensitive cells - so called respiratory chemoreceptors. Subsets of brainstem serotonin (5-HT) neurons in the medullary raphe are CO2 sensitive or insensitive based on differences in embryonic origin, suggesting these functionally distinct subpopulations may have unique transcriptional profiles. Here, we used Patch-to-Seq to determine if the CO2 responses in brainstem 5-HT neurons could be correlated to unique transcriptional profiles and/or unique molecular markers and pathways. First, firing rate changes with hypercapnic acidosis were measured in fluorescently labeled 5-HT neurons in acute brainstem slices from transgenic, Dahl SS (SSMcwi) rats expressing T2/ePet-eGFP transgene in Pet-1 expressing (serotonin) neurons (SS ePet1-eGFP rats). Subsequently, the transcriptomic and pathway profiles of CO2 sensitive and insensitive 5-HT neurons were determined and compared by single cell RNA (scRNAseq) and bioinformatic analyses. Low baseline firing rates were a distinguishing feature of CO2 sensitive 5-HT neurons. scRNAseq of these recorded neurons revealed 166 differentially expressed genes among CO2 sensitive and insensitive 5-HT neurons. Pathway analyses yielded novel predicted upstream regulators, including the transcription factor Egr2 and Leptin. Additional bioinformatic analyses identified 6 candidate gene markers of CO2 sensitive 5-HT neurons, and 2 selected candidate genes (CD46 and Iba57) were both expressed in 5-HT neurons determined via in situ mRNA hybridization. Together, these data provide novel insights into the transcriptional control of cellular chemoreception and provide unbiased candidate gene markers of CO2 sensitive 5-HT neurons. Methodologically, these data highlight the utility of the patch-to-seq technique in enabling the linkage of gene expression to specific functions, like CO2 chemoreception, in a single cell to identify potential mechanisms underlying functional differences in otherwise similar cell types.
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Affiliation(s)
- Gary C. Mouradian
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States,Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI, United States,*Correspondence: Gary C. Mouradian Jr.,
| | - Pengyuan Liu
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Pablo Nakagawa
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Erin Duffy
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Javier Gomez Vargas
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Kirthikaa Balapattabi
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Justin L. Grobe
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States,Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI, United States,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States,Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI, United States,Comprehensive Rodent Metabolic Phenotyping Core, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Curt D. Sigmund
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States,Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI, United States,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Matthew R. Hodges
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States,Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI, United States
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9
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Yu H, Shi L, Chen J, Jun S, Hao Y, Wang S, Fu C, Zhang X, Lu H, Wang S, Yuan F. A Neural Circuit Mechanism Controlling Breathing by Leptin in the Nucleus Tractus Solitarii. Neurosci Bull 2021; 38:149-165. [PMID: 34212297 PMCID: PMC8821766 DOI: 10.1007/s12264-021-00742-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 05/07/2021] [Indexed: 02/03/2023] Open
Abstract
Leptin, an adipocyte-derived peptide hormone, has been shown to facilitate breathing. However, the central sites and circuit mechanisms underlying the respiratory effects of leptin remain incompletely understood. The present study aimed to address whether neurons expressing leptin receptor b (LepRb) in the nucleus tractus solitarii (NTS) contribute to respiratory control. Both chemogenetic and optogenetic stimulation of LepRb-expressing NTS (NTSLepRb) neurons notably activated breathing. Moreover, stimulation of NTSLepRb neurons projecting to the lateral parabrachial nucleus (LPBN) not only remarkably increased basal ventilation to a level similar to that of the stimulation of all NTSLepRb neurons, but also activated LPBN neurons projecting to the preBötzinger complex (preBötC). By contrast, ablation of NTSLepRb neurons projecting to the LPBN notably eliminated the enhanced respiratory effect induced by NTSLepRb neuron stimulation. In brainstem slices, bath application of leptin rapidly depolarized the membrane potential, increased the spontaneous firing rate, and accelerated the Ca2+ transients in most NTSLepRb neurons. Therefore, leptin potentiates breathing in the NTS most likely via an NTS-LPBN-preBötC circuit.
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Affiliation(s)
- Hongxiao Yu
- grid.256883.20000 0004 1760 8442Department of Physiology, Hebei Medical University, Shijiazhuang, 050017 Hebei China
| | - Luo Shi
- grid.256883.20000 0004 1760 8442Department of Physiology, Hebei Medical University, Shijiazhuang, 050017 Hebei China
| | - Jinting Chen
- grid.256883.20000 0004 1760 8442Core Facilities and Centers, Institute of Medicine and Health, Hebei Medical University, Shijiazhuang, 050017 Hebei China
| | - Shirui Jun
- grid.256883.20000 0004 1760 8442Department of Physiology, Hebei Medical University, Shijiazhuang, 050017 Hebei China
| | - Yinchao Hao
- grid.256883.20000 0004 1760 8442Department of Physiology, Hebei Medical University, Shijiazhuang, 050017 Hebei China
| | - Shuang Wang
- grid.256883.20000 0004 1760 8442Department of Physiology, Hebei Medical University, Shijiazhuang, 050017 Hebei China
| | - Congrui Fu
- grid.256883.20000 0004 1760 8442School of Nursing, Hebei Medical University, Shijiazhuang, 050000 Hebei China
| | - Xiang Zhang
- grid.256883.20000 0004 1760 8442Department of Physiology, Hebei Medical University, Shijiazhuang, 050017 Hebei China
| | - Haiyan Lu
- grid.256883.20000 0004 1760 8442Department of Orthodontics, College of Stomatology, Hebei Medical University, Shijiazhuang, 050017 Hebei China
| | - Sheng Wang
- grid.256883.20000 0004 1760 8442Department of Physiology, Hebei Medical University, Shijiazhuang, 050017 Hebei China ,Hebei Key Laboratory of Neurophysiology, Shijiazhuang, 050017 Hebei China
| | - Fang Yuan
- grid.256883.20000 0004 1760 8442Department of Physiology, Hebei Medical University, Shijiazhuang, 050017 Hebei China ,Hebei Key Laboratory of Neurophysiology, Shijiazhuang, 050017 Hebei China
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Amorim MR, Dergacheva O, Fleury-Curado T, Pho H, Freire C, Mendelowitz D, Branco LGS, Polotsky VY. The Effect of DREADD Activation of Leptin Receptor Positive Neurons in the Nucleus of the Solitary Tract on Sleep Disordered Breathing. Int J Mol Sci 2021; 22:6742. [PMID: 34201760 PMCID: PMC8269100 DOI: 10.3390/ijms22136742] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 06/19/2021] [Indexed: 12/14/2022] Open
Abstract
Obstructive sleep apnea (OSA) is recurrent obstruction of the upper airway due to the loss of upper airway muscle tone during sleep. OSA is highly prevalent, especially in obesity. There is no pharmacotherapy for OSA. Previous studies have demonstrated the role of leptin, an adipose-tissue-produced hormone, as a potent respiratory stimulant. Leptin signaling via a long functional isoform of leptin receptor, LEPRb, in the nucleus of the solitary tract (NTS), has been implicated in control of breathing. We hypothesized that leptin acts on LEPRb positive neurons in the NTS to increase ventilation and maintain upper airway patency during sleep in obese mice. We expressed designer receptors exclusively activated by designer drugs (DREADD) selectively in the LEPRb positive neurons of the NTS of Leprb-Cre-GFP mice with diet-induced obesity (DIO) and examined the effect of DREADD ligand, J60, on tongue muscle activity and breathing during sleep. J60 was a potent activator of LEPRb positive NTS neurons, but did not stimulate breathing or upper airway muscles during NREM and REM sleep. We conclude that, in DIO mice, the stimulating effects of leptin on breathing during sleep are independent of LEPRb signaling in the NTS.
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Affiliation(s)
- Mateus R. Amorim
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA; (T.F.-C.); (H.P.); (C.F.)
- Dental School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo 14040-904, Brazil;
| | - Olga Dergacheva
- Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA; (O.D.); (D.M.)
| | - Thomaz Fleury-Curado
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA; (T.F.-C.); (H.P.); (C.F.)
| | - Huy Pho
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA; (T.F.-C.); (H.P.); (C.F.)
| | - Carla Freire
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA; (T.F.-C.); (H.P.); (C.F.)
| | - David Mendelowitz
- Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA; (O.D.); (D.M.)
| | - Luiz G. S. Branco
- Dental School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo 14040-904, Brazil;
| | - Vsevolod Y. Polotsky
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA; (T.F.-C.); (H.P.); (C.F.)
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11
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Pho H, Berger S, Freire C, Kim LJ, Shin MK, Streeter SR, Hosamane N, Cabassa ME, Anokye-Danso F, Dergacheva O, Amorim MR, Fleury-Curado T, Jun JC, Schwartz AR, Ahima RS, Mendelowitz D, Polotsky VY. Leptin receptor expression in the dorsomedial hypothalamus stimulates breathing during NREM sleep in db/db mice. Sleep 2021; 44:6149135. [PMID: 33624805 PMCID: PMC8193564 DOI: 10.1093/sleep/zsab046] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 02/06/2021] [Indexed: 12/12/2022] Open
Abstract
STUDY OBJECTIVES Obesity leads to obstructive sleep apnea (OSA), which is recurrent upper airway obstruction during sleep, and obesity hypoventilation syndrome (OHS), hypoventilation during sleep resulting in daytime hypercapnia. Impaired leptin signaling in the brain was implicated in both conditions, but mechanisms are unknown. We have previously shown that leptin stimulates breathing and treats OSA and OHS in leptin-deficient ob/ob mice and leptin-resistant diet-induced obese mice and that leptin's respiratory effects may occur in the dorsomedial hypothalamus (DMH). We hypothesized that leptin receptor LepRb-deficient db/db mice have obesity hypoventilation and that restoration of leptin signaling in the DMH will increase ventilation during sleep in these animals. METHODS We measured arterial blood gas in unanesthetized awake db/db mice. We subsequently infected these animals with Ad-LepRb or control Ad-mCherry virus into the DMH and measured ventilation during sleep as well as CO2 production after intracerebroventricular (ICV) infusions of phosphate-buffered saline or leptin. RESULTS Awake db/db mice had elevated CO2 levels in the arterial blood. Ad-LepRb infection resulted in LepRb expression in the DMH neurons in a similar fashion to wildtype mice. In LepRb-DMH db/db mice, ICV leptin shortened REM sleep and increased inspiratory flow, tidal volume, and minute ventilation during NREM sleep without any effect on the quality of NREM sleep or CO2 production. Leptin had no effect on upper airway obstruction in these animals. CONCLUSION Leptin stimulates breathing and treats obesity hypoventilation acting on LepRb-positive neurons in the DMH.
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Affiliation(s)
- Huy Pho
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Slava Berger
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Carla Freire
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Lenise J Kim
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Mi-Kyung Shin
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Stone R Streeter
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Nishitha Hosamane
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Meaghan E Cabassa
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Frederick Anokye-Danso
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Olga Dergacheva
- Department of Pharmacology and Physiology, George Washington University, Washington, DC, USA
| | - Mateus R Amorim
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Thomaz Fleury-Curado
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jonathan C Jun
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Alan R Schwartz
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Rexford S Ahima
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David Mendelowitz
- Department of Pharmacology and Physiology, George Washington University, Washington, DC, USA
| | - Vsevolod Y Polotsky
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Corresponding author. Vsevolod (Seva) Y. Polotsky, Division of Pulmonary and Critical Care Medicine, Department of Medicine, The Johns Hopkins University School of Medicine, 5501 Hopkins Bayview Circle, Johns Hopkins Asthma and Allergy Center, Rm 4B65, Baltimore, MD 21224.
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12
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Moreira TS, Sobrinho CR, Falquetto B, Oliveira LM, Lima JD, Mulkey DK, Takakura AC. The retrotrapezoid nucleus and the neuromodulation of breathing. J Neurophysiol 2020; 125:699-719. [PMID: 33427575 DOI: 10.1152/jn.00497.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Breathing is regulated by a host of arousal and sleep-wake state-dependent neuromodulators to maintain respiratory homeostasis. Modulators such as acetylcholine, norepinephrine, histamine, serotonin (5-HT), adenosine triphosphate (ATP), substance P, somatostatin, bombesin, orexin, and leptin can serve complementary or off-setting functions depending on the target cell type and signaling mechanisms engaged. Abnormalities in any of these modulatory mechanisms can destabilize breathing, suggesting that modulatory mechanisms are not overly redundant but rather work in concert to maintain stable respiratory output. The present review focuses on the modulation of a specific cluster of neurons located in the ventral medullary surface, named retrotrapezoid nucleus, that are activated by changes in tissue CO2/H+ and regulate several aspects of breathing, including inspiration and active expiration.
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Affiliation(s)
- Thiago S Moreira
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Cleyton R Sobrinho
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Barbara Falquetto
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Luiz M Oliveira
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Janayna D Lima
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut
| | - Ana C Takakura
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
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13
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A Leptin-Mediated Neural Mechanism Linking Breathing to Metabolism. Cell Rep 2020; 33:108358. [PMID: 33176139 DOI: 10.1016/j.celrep.2020.108358] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 08/27/2020] [Accepted: 10/16/2020] [Indexed: 01/10/2023] Open
Abstract
Breathing is coupled to metabolism. Leptin, a peptide mainly secreted in proportion to adipose tissue mass, increases energy expenditure with a parallel increase in breathing. We demonstrate that optogenetic activation of LepRb neurons in the nucleus of the solitary tract (NTS) mimics the respiratory stimulation after systemic leptin administration. We show that leptin activates the sodium leak channel (NALCN), thereby depolarizing a subset of glutamatergic (VGluT2) LepRb NTS neurons expressing galanin. Mice with selective deletion of NALCN in LepRb neurons have increased breathing irregularity and central apneas. On a high-fat diet, these mice gain weight with an associated depression of minute ventilation and tidal volume, which are not detected in control littermates. Anatomical mapping reveals LepRb NTS-originating glutamatergic axon terminals in a brainstem inspiratory premotor region (rVRG) and dorsomedial hypothalamus. These findings directly link a defined subset of NTS LepRb cells to the matching of ventilation to energy balance.
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14
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Gauda EB, Conde S, Bassi M, Zoccal DB, Almeida Colombari DS, Colombari E, Despotovic N. Leptin: Master Regulator of Biological Functions that Affects Breathing. Compr Physiol 2020; 10:1047-1083. [PMID: 32941688 DOI: 10.1002/cphy.c190031] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Obesity is a global epidemic in developed countries accounting for many of the metabolic and cardiorespiratory morbidities that occur in adults. These morbidities include type 2 diabetes, sleep-disordered breathing (SDB), obstructive sleep apnea, chronic intermittent hypoxia, and hypertension. Leptin, produced by adipocytes, is a master regulator of metabolism and of many other biological functions including central and peripheral circuits that control breathing. By binding to receptors on cells and neurons in the brainstem, hypothalamus, and carotid body, leptin links energy and metabolism to breathing. In this comprehensive article, we review the central and peripheral locations of leptin's actions that affect cardiorespiratory responses during health and disease, with a particular focus on obesity, SDB, and its effects during early development. Obesity-induced hyperleptinemia is associated with centrally mediated hypoventilation with decrease CO2 sensitivity. On the other hand, hyperleptinemia augments peripheral chemoreflexes to hypoxia and induces sympathoexcitation. Thus, "leptin resistance" in obesity is relative. We delineate the circuits responsible for these divergent effects, including signaling pathways. We review the unique effects of leptin during development on organogenesis, feeding behavior, and cardiorespiratory responses, and how undernutrition and overnutrition during critical periods of development can lead to cardiorespiratory comorbidities in adulthood. We conclude with suggestions for future directions to improve our understanding of leptin dysregulation and associated clinical diseases and possible therapeutic targets. Lastly, we briefly discuss the yin and the yang, specifically the contribution of relative adiponectin deficiency in adults with hyperleptinemia to the development of metabolic and cardiovascular disease. © 2020 American Physiological Society. Compr Physiol 10:1047-1083, 2020.
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Affiliation(s)
- Estelle B Gauda
- Division of Neonatology, Department of Pediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Silvia Conde
- CEDOC, NOVA Medical School, Faculdade de Ciências Médicas, Lisboa, Portugal
| | - Mirian Bassi
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, São Paulo, Brazil
| | - Daniel B Zoccal
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, São Paulo, Brazil
| | - Debora Simoes Almeida Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, São Paulo, Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, São Paulo, Brazil
| | - Nikola Despotovic
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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15
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Disordered Leptin signaling in the retrotrapezoid nucleus is associated with the impaired hypercapnic ventilatory response in obesity. Life Sci 2020; 257:117994. [PMID: 32569780 DOI: 10.1016/j.lfs.2020.117994] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/15/2020] [Accepted: 06/18/2020] [Indexed: 12/16/2022]
Abstract
Sleep-disordered breathing is characterized by disruptions of normal breathing patterns during sleep. Obesity is closely related to hypoventilation or apnea and becomes a primary risk factor for sleep-disordered breathing. Leptin, a peptide secreted by adipose tissue, has been implicated in central control of breathing. Activation of the retrotrapezoid nucleus (RTN) neurons, a critical central respiratory chemoreceptor candidate, potentiates a central drive to breathing. Here, we ask whether the disordered leptin signaling in the RTN is responsible for obesity-related hypoventilation. In a diet induced obesity (DIO) mouse model, the hypercapnic ventilatory response (HCVR) was assessed and the cellular leptin signaling in the RTN was examined. Our main findings demonstrate that DIO mice exhibit overweight, hypercapnia, high levels of serum and cerebrospinal leptin. During exposure to room air, DIO mice manifest basal hypoventilation with a rapid and shallow breathing pattern. Exposure to CO2 elicits the impaired HCVR in DIO mice. In addition, both the number of CO2-activated neurons and expression of TASK-2 channels in the RTN are dramatically reduced in DIO mice. Moreover, there is leptin signaling disorder in RTN neurons in DIO mice, including a significant decrease in leptin-activated RTN neurons, downregulation of phosphorylated STAT3 and upregulation of SOCS3. Altogether, we suggest that the disordered leptin/STAT3/SOCS3 signaling pathway in the RTN plays a role in obesity-related hypoventilation.
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16
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Shin MK, Kim LJ, Caballero-Eraso C, Polotsky VY. Experimental Approach to Examine Leptin Signaling in the Carotid Bodies and its Effects on Control of Breathing. J Vis Exp 2019. [PMID: 31710041 DOI: 10.3791/60298] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
An adipocyte-produced hormone leptin is a potent respiratory stimulant, which may play an important role in defending respiratory function in obesity. The carotid bodies (CB), a key organ of peripheral hypoxic sensitivity, express the long functional isoform of leptin receptor (LepRb) but the role of leptin signaling in control of breathing has not been fully elucidated. We examined the hypoxic ventilatory response (HVR) (1) in C57BL/6J mice before and after leptin infusion at baseline and after CB denervation; (2) in LepRb-deficient obese db/db mice at baseline and after LepRb overexpression in CBs. In C57BL/6J mice, leptin increased HVR and effects of leptin on HVR were abolished by CB denervation. In db/db mice, LepRb expression in CB augmented the HVR. Therefore, we conclude that leptin acts in CB to augment responses to hypoxia.
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Affiliation(s)
| | - Lenise J Kim
- Department of Medicine, Johns Hopkins University
| | - Candela Caballero-Eraso
- Instituto de Biomedicina de Sevilla (IBiS), Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Hospital Universitario Virgen del Rocío/Universidad de Sevilla
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17
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Speretta GF, Lemes EV, Vendramini RC, Menani JV, Zoccal DB, Colombari E, Colombari DSA, Bassi M. High-fat diet increases respiratory frequency and abdominal expiratory motor activity during hypercapnia. Respir Physiol Neurobiol 2018; 258:32-39. [PMID: 30308245 PMCID: PMC6317333 DOI: 10.1016/j.resp.2018.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 10/05/2018] [Accepted: 10/06/2018] [Indexed: 11/24/2022]
Abstract
Breathing disorders are commonly observed in association with obesity. Here we tested whether high-fat diet (HFD) impairs the chemoreflex ventilatory response. Male Holtzman rats (300-320 g) were fed with standard chow diet (SD) or HFD for 12 weeks. Then, tidal volume (VT), respiratory frequency (fR) and pulmonary ventilation (VE) were determined in conscious rats during basal condition, hypercapnia (7% or 10% CO2) or hypoxia (7% O2). The mean arterial pressure (MAP), heart rate (HR) and baroreflex sensitivity were also evaluated in conscious rats. A group of anesthetized rats was used for the measurements of the activity of inspiratory (diaphragm) and expiratory (abdominal) muscles under the same gas conditions. Baseline fR, VT and VE were similar between SD and HFD rats. During hypercapnia, the increase of fR was exacerbated in conscious HFD rats (60 ± 3, vs. SD: 47 ± 3 Δ breaths.min-1, P < 0.05). In anesthetized rats, hypercapnia strongly increased abdominal muscle activity in HFD group (238 ± 27, vs. basal condition: 100 ± 0.3%; P < 0.05), without significant change in SD group (129 ± 2.1, vs. basal condition: 100 ± 0.8%; P = 0.34). The ventilatory responses to hypoxia were similar between groups. In conscious HFD rats, MAP and HR were elevated and the baroreflex function was impaired (P < 0.05). These data demonstrated that 12 weeks of HFD exaggerate the ventilatory response activated by hypercapnia. The mechanisms involved in these responses need more investigation in future studies.
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Affiliation(s)
- Guilherme F Speretta
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil.
| | - Eduardo Vieira Lemes
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Regina C Vendramini
- Department of Clinical Analysis, School of Pharmaceutical Sciences, UNESP, Araraquara, SP, Brazil
| | - José V Menani
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Daniel B Zoccal
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Eduardo Colombari
- 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
| | - Mirian Bassi
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil.
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18
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Caballero-Eraso C, Shin MK, Pho H, Kim LJ, Pichard LE, Wu ZJ, Gu C, Berger S, Pham L, Yeung HYB, Shirahata M, Schwartz AR, Tang WYW, Sham JSK, Polotsky VY. Leptin acts in the carotid bodies to increase minute ventilation during wakefulness and sleep and augment the hypoxic ventilatory response. J Physiol 2018; 597:151-172. [PMID: 30285278 DOI: 10.1113/jp276900] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 10/03/2018] [Indexed: 01/10/2023] Open
Abstract
KEY POINTS Leptin is a potent respiratory stimulant. A long functional isoform of leptin receptor, LepRb , was detected in the carotid body (CB), a key peripheral hypoxia sensor. However, the effect of leptin on minute ventilation (VE ) and the hypoxic ventilatory response (HVR) has not been sufficiently studied. We report that LepRb is present in approximately 74% of the CB glomus cells. Leptin increased carotid sinus nerve activity at baseline and in response to hypoxia in vivo. Subcutaneous infusion of leptin increased VE and HVR in C57BL/6J mice and this effect was abolished by CB denervation. Expression of LepRb in the carotid bodies of LepRb deficient obese db/db mice increased VE during wakefulness and sleep and augmented the HVR. We conclude that leptin acts on LepRb in the CBs to stimulate breathing and HVR, which may protect against sleep disordered breathing in obesity. ABSTRACT Leptin is a potent respiratory stimulant. The carotid bodies (CB) express the long functional isoform of leptin receptor, LepRb , but the role of leptin in CB has not been fully elucidated. The objectives of the current study were (1) to examine the effect of subcutaneous leptin infusion on minute ventilation (VE ) and the hypoxic ventilatory response to 10% O2 (HVR) in C57BL/6J mice before and after CB denervation; (2) to express LepRb in CB of LepRb -deficient obese db/db mice and examine its effects on breathing during sleep and wakefulness and on HVR. We found that leptin enhanced carotid sinus nerve activity at baseline and in response to 10% O2 in vivo. In C57BL/6J mice, leptin increased VE from 1.1 to 1.5 mL/min/g during normoxia (P < 0.01) and from 3.6 to 4.7 mL/min/g during hypoxia (P < 0.001), augmenting HVR from 0.23 to 0.31 mL/min/g/Δ F I O 2 (P < 0.001). The effects of leptin on VE and HVR were abolished by CB denervation. In db/db mice, LepRb expression in CB increased VE from 1.1 to 1.3 mL/min/g during normoxia (P < 0.05) and from 2.8 to 3.2 mL/min/g during hypoxia (P < 0.02), increasing HVR. Compared to control db/db mice, LepRb transfected mice showed significantly higher VE throughout non-rapid eye movement (20.1 vs. -27.7 mL/min respectively, P < 0.05) and rapid eye movement sleep (16.5 vs 23.4 mL/min, P < 0.05). We conclude that leptin acts in CB to augment VE and HVR, which may protect against sleep disordered breathing in obesity.
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Affiliation(s)
- Candela Caballero-Eraso
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Unidad Médico-Quirúrgica de Enfermedades Respiratorias, Instituto de Biomedicina de Sevilla (IBiS), Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Hospital Universitario Virgen del Rocío/Universidad de Sevilla, Sevilla, Spain
| | - Mi-Kyung Shin
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Huy Pho
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Lenise J Kim
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Departamento de Psicobiologia, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Luis E Pichard
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Zhi-Juan Wu
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Chenjuan Gu
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Slava Berger
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Luu Pham
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ho-Yee Bonnie Yeung
- Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Machiko Shirahata
- Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Alan R Schwartz
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Wan-Yee Winnie Tang
- Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - James S K Sham
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Vsevolod Y Polotsky
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Abstract
Leptin is a peptide hormone produced mainly in white adipose tissue. It is known to regulate energy homeostasis, inflammation, metabolism, and sympathetic nerve activity. Increasing evidence suggests it has a role in ventilatory function and upper airway obstruction. Leptin levels correlate positively with measurements of adiposity and can potentially provide important insights into the pathophysiology of diseases associated with obesity. Obesity is a strong risk factor for obstructive sleep apnea, a disease characterized by periodic upper airway occlusion during sleep. The neuromuscular activity that maintains upper airway patency during sleep and the anatomy of upper airway are key factors involved in its pathogenesis. Experimental studies using animal models of a low leptin state such as leptin deficiency have shown that leptin regulates sleep architecture, upper airway patency, ventilatory function, and hypercapnic ventilatory response. However, findings from human studies do not consistently support the data from the animal models. The effect of leptin on the pathophysiology of obstructive sleep apnea is being investigated, but the results of studies have been confounded by leptin's diurnal variation and the short-term effects of feeding, adiposity, age, and sex. Improved study design and methods of assessing functional leptin levels, specifically their central versus peripheral effects, will improve understanding of the role of leptin in sleep apnea.
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Angel C, Glovak ZT, Alami W, Mihalko S, Price J, Jiang Y, Baghdoyan HA, Lydic R. Buprenorphine Depresses Respiratory Variability in Obese Mice with Altered Leptin Signaling. Anesthesiology 2018; 128:984-991. [PMID: 29394163 PMCID: PMC5903969 DOI: 10.1097/aln.0000000000002073] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Opiate-induced respiratory depression is sexually dimorphic and associated with increased risk among the obese. The mechanisms underlying these associations are unknown. The present study evaluated the two-tailed hypothesis that sex, leptin status, and obesity modulate buprenorphine-induced changes in breathing. METHODS Mice (n = 40 male and 40 female) comprising four congenic lines that differ in leptin signaling and body weight were injected with saline and buprenorphine (0.3 mg/kg). Whole-body plethysmography was used to quantify the effects on minute ventilation. The data were evaluated using three-way analysis of variance, regression, and Poincaré analyses. RESULTS Relative to B6 mice with normal leptin, buprenorphine decreased minute ventilation in mice with diet-induced obesity (37.2%; P < 0.0001), ob/ob mice that lack leptin (62.6%; P < 0.0001), and db/db mice with dysfunctional leptin receptors (65.9%; P < 0.0001). Poincaré analyses showed that buprenorphine caused a significant (P < 0.0001) collapse in minute ventilation variability that was greatest in mice with leptin dysfunction. There was no significant effect of sex or body weight on minute ventilation. CONCLUSIONS The results support the interpretation that leptin status but not body weight or sex contributed to the buprenorphine-induced decrease in minute ventilation. Poincaré plots illustrate that the buprenorphine-induced decrease in minute ventilation variability was greatest in mice with impaired leptin signaling. This is relevant because normal respiratory variability is essential for martialing a compensatory response to ventilatory challenges imposed by disease, obesity, and surgical stress.
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Affiliation(s)
- Chelsea Angel
- Department of Anesthesiology, University of Tennessee, Knoxville, TN
| | - Zachary T. Glovak
- Department of Anesthesiology, University of Tennessee, Knoxville, TN
- Department of Psychology, University of Tennessee, Knoxville, TN
| | - Wateen Alami
- Department of Anesthesiology, University of Tennessee, Knoxville, TN
| | - Sara Mihalko
- Department of Anesthesiology, University of Tennessee, Knoxville, TN
| | - Josh Price
- Department of Information Technology, University of Tennessee, Knoxville, TN
| | - Yandong Jiang
- Department of Anesthesiology, Vanderbilt University, Nashville, TN
| | - Helen A. Baghdoyan
- Department of Anesthesiology, University of Tennessee, Knoxville, TN
- Department of Psychology, University of Tennessee, Knoxville, TN
- Oak Ridge National Laboratory, Oak Ridge, TN
| | - Ralph Lydic
- Department of Anesthesiology, University of Tennessee, Knoxville, TN
- Department of Psychology, University of Tennessee, Knoxville, TN
- Oak Ridge National Laboratory, Oak Ridge, TN
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21
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Yuan F, Wang H, Feng J, Wei Z, Yu H, Zhang X, Zhang Y, Wang S. Leptin Signaling in the Carotid Body Regulates a Hypoxic Ventilatory Response Through Altering TASK Channel Expression. Front Physiol 2018; 9:249. [PMID: 29636698 PMCID: PMC5881163 DOI: 10.3389/fphys.2018.00249] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 03/06/2018] [Indexed: 11/23/2022] Open
Abstract
Leptin is an adipose-derived hormone that plays an important role in the regulation of breathing. It has been demonstrated that obesity-related hypoventilation or apnea is closely associated with leptin signaling pathways. Perturbations of leptin signaling probably contribute to the reduced sensitivity of respiratory chemoreceptors to hypoxia/hypercapnia. However, the underlying mechanism remains incompletely understood. The present study is to test the hypothesis that leptin signaling contributes to modulating a hypoxic ventilatory response. The respiratory function was assessed in conscious obese Zucker rats or lean littermates treated with an injection of leptin. During exposure to hypoxia, the change in minute ventilation was lower in obese Zucker rats than chow-fed lean littermates or high fat diet-fed littermates. Such a change was abolished in all groups after carotid body denervation. In addition, the expression of phosphorylated signal transducers and activators of transcription 3 (pSTAT3), as well as putative O2-sensitive K+ channels including TASK-1, TASK-3 and TASK-2 in the carotid body, was significantly reduced in obese Zucker rats compared with the other two phenotype littermates. Chronic administration of leptin in chow-fed lean Zucker rats failed to alter basal ventilation but vigorously increased tidal volume, respiratory frequency, and therefore minute volume during exposure to hypoxia. Likewise, carotid body denervation abolished such an effect. In addition, systemic leptin elicited enhanced expression of pSTAT3 and TASK channels. In conclusion, these data demonstrate that leptin signaling facilitates hypoxic ventilatory responses probably through upregulation of pSTAT3 and TASK channels in the carotid body. These findings may help to better understand the pathogenic mechanism of obesity-related hypoventilation or apnea.
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Affiliation(s)
- Fang Yuan
- Department of Physiology, Hebei Medical University, Shijiazhuang, China.,Hebei Key Laboratory of Vascular Homeostasis and Hebei Collaborative Innovation Center for Cardio-Cerebrovascular Disease, Shijiazhuang, China
| | - Hanqiao Wang
- Department of Sleep, Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Jiaqi Feng
- Department of Physiology, Hebei Medical University, Shijiazhuang, China
| | - Ziqian Wei
- Department of Physiology, Hebei Medical University, Shijiazhuang, China
| | - Hongxiao Yu
- Department of Physiology, Hebei Medical University, Shijiazhuang, China
| | - Xiangjian Zhang
- Hebei Key Laboratory of Vascular Homeostasis and Hebei Collaborative Innovation Center for Cardio-Cerebrovascular Disease, Shijiazhuang, China.,Department of Neurology, Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Yi Zhang
- Department of Physiology, Hebei Medical University, Shijiazhuang, China.,Hebei Key Laboratory of Vascular Homeostasis and Hebei Collaborative Innovation Center for Cardio-Cerebrovascular Disease, Shijiazhuang, China
| | - Sheng Wang
- Department of Physiology, Hebei Medical University, Shijiazhuang, China.,Hebei Key Laboratory of Vascular Homeostasis and Hebei Collaborative Innovation Center for Cardio-Cerebrovascular Disease, Shijiazhuang, China
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22
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Kaczyńska K, Zając D, Wojciechowski P, Kogut E, Szereda-Przestaszewska M. Neuropeptides and breathing in health and disease. Pulm Pharmacol Ther 2017; 48:217-224. [PMID: 29223509 DOI: 10.1016/j.pupt.2017.12.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 11/20/2017] [Accepted: 12/05/2017] [Indexed: 12/18/2022]
Abstract
Regulatory neuropeptides control and regulate breathing in physiological and pathophysiological conditions. While they have been identified in the neurons of major respiratory areas, they can be active not only at the central level, but also at the periphery via chemoreceptors, vagal afferents, or locally within lungs and airways. Some neuropeptides, such as leptin or substance P, are respiratory stimulants; others, such as neurotensin, produce variable effects on respiration depending on the site of application. Some neuropeptides have been implicated in pathological states, such as obstructive sleep apnea or asthma. This article provides a concise review of the possible role and functions of several selected neuropeptides in the process of breathing in health and disease and in lung pathologies.
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Affiliation(s)
- Katarzyna Kaczyńska
- Laboratory of Respiration Physiology, Mossakowski Medical Research Centre Polish Academy of Sciences, Warsaw, Poland.
| | - Dominika Zając
- Laboratory of Respiration Physiology, Mossakowski Medical Research Centre Polish Academy of Sciences, Warsaw, Poland
| | - Piotr Wojciechowski
- Laboratory of Respiration Physiology, Mossakowski Medical Research Centre Polish Academy of Sciences, Warsaw, Poland
| | - Ewelina Kogut
- Laboratory of Respiration Physiology, Mossakowski Medical Research Centre Polish Academy of Sciences, Warsaw, Poland
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23
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Costa-Silva JH, Simões-Alves AC, Fernandes MP. Developmental Origins of Cardiometabolic Diseases: Role of the Maternal Diet. Front Physiol 2016; 7:504. [PMID: 27899895 PMCID: PMC5110566 DOI: 10.3389/fphys.2016.00504] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Accepted: 10/14/2016] [Indexed: 01/21/2023] Open
Abstract
Developmental origins of cardiometabolic diseases have been related to maternal nutritional conditions. In this context, the rising incidence of arterial hypertension, diabetes type II, and dyslipidemia has been attributed to genetic programming. Besides, environmental conditions during perinatal development such as maternal undernutrition or overnutrition can program changes in the integration among physiological systems leading to cardiometabolic diseases. This phenomenon can be understood in the context of the phenotypic plasticity and refers to the adjustment of a phenotype in response to environmental input without genetic change, following a novel, or unusual input during development. Experimental studies indicate that fetal exposure to an adverse maternal environment may alter the morphology and physiology that contribute to the development of cardiometabolic diseases. It has been shown that both maternal protein restriction and overnutrition alter the central and peripheral control of arterial pressure and metabolism. This review will address the new concepts on the maternal diet induced-cardiometabolic diseases that include the potential role of the perinatal malnutrition.
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Affiliation(s)
- João H Costa-Silva
- Departamento de Educação Física e Ciências do Esporte, Centro Acadêmico de Vitória, Universidade Federal de Pernambuco Pernambuco, Brazil
| | - Aiany C Simões-Alves
- Departamento de Educação Física e Ciências do Esporte, Centro Acadêmico de Vitória, Universidade Federal de Pernambuco Pernambuco, Brazil
| | - Mariana P Fernandes
- Departamento de Educação Física e Ciências do Esporte, Centro Acadêmico de Vitória, Universidade Federal de Pernambuco Pernambuco, Brazil
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24
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Yao Q, Pho H, Kirkness J, Ladenheim EE, Bi S, Moran TH, Fuller DD, Schwartz AR, Polotsky VY. Localizing Effects of Leptin on Upper Airway and Respiratory Control during Sleep. Sleep 2016; 39:1097-106. [PMID: 26951402 DOI: 10.5665/sleep.5762] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 02/01/2016] [Indexed: 12/30/2022] Open
Abstract
STUDY OBJECTIVES Obesity hypoventilation and obstructive sleep apnea are common complications of obesity linked to defects in respiratory pump and upper airway neural control. Leptin-deficient ob/ob mice have impaired ventilatory control and inspiratory flow limitation during sleep, which are both reversed with leptin. We aimed to localize central nervous system (CNS) site(s) of leptin action on respiratory and upper airway neuroventilatory control. METHODS We localized the effect of leptin to medulla versus hypothalamus by administering intracerbroventricular leptin (10 μg/2 μL) versus vehicle to the lateral (n = 14) versus fourth ventricle (n = 11) of ob/ob mice followed by polysomnographic recording. Analyses were stratified for effects on respiratory (nonflow-limited breaths) and upper airway (inspiratory flow limitation) functions. CNS loci were identified by (1) leptin-induced signal transducer and activator of transcription 3 (STAT3) phosphorylation and (2) projections of respiratory and upper airway motoneurons with a retrograde transsynaptic tracer (pseudorabies virus). RESULTS Both routes of leptin administration increased minute ventilation during nonflow-limited breathing in sleep. Phrenic motoneurons were synaptically coupled to the nucleus of the solitary tract, which also showed STAT3 phosphorylation, but not to the hypothalamus. Inspiratory flow limitation and obstructive hypopneas were attenuated by leptin administration to the lateral but not to the fourth cerebral ventricle. Upper airway motoneurons were synaptically coupled with the dorsomedial hypothalamus, which exhibited STAT3 phosphorylation. CONCLUSIONS Leptin relieves upper airway obstruction in sleep apnea by activating the forebrain, possibly in the dorsomedial hypothalamus. In contrast, leptin upregulates ventilatory control through hindbrain sites of action, possibly in the nucleus of the solitary tract.
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Affiliation(s)
- Qiaoling Yao
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD.,Department of Physiology; Preclinical School, Xinjiang Medical University, Xinjiang, China
| | - Huy Pho
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Jason Kirkness
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Ellen E Ladenheim
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Sheng Bi
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Timothy H Moran
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD
| | - David D Fuller
- Departments of Physical Therapy, University of Florida, Gainesville, FL.,McKnight Brain Institute, University of Florida, Gainesville, FL
| | - Alan R Schwartz
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Vsevolod Y Polotsky
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
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25
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Bassi M, Furuya WI, Zoccal DB, Menani JV, Colombari DSA, Mulkey DK, Colombari E. Facilitation of breathing by leptin effects in the central nervous system. J Physiol 2016; 594:1617-25. [PMID: 26095748 PMCID: PMC4799963 DOI: 10.1113/jp270308] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 05/13/2015] [Indexed: 01/01/2023] Open
Abstract
With the global epidemic of obesity, breathing disorders associated with excess body weight have markedly increased. Respiratory dysfunctions caused by obesity were originally attributed to mechanical factors; however, recent studies have suggested a pathophysiological component that involves the central nervous system (CNS) and hormones such as leptin produced by adipocytes as well as other cells. Leptin is suggested to stimulate breathing and leptin deficiency causes an impairment of the chemoreflex, which can be reverted by leptin therapy. This facilitation of the chemoreflex may depend on the action of leptin in the hindbrain areas involved in the respiratory control such as the nucleus of the solitary tract (NTS), a site that receives chemosensory afferents, and the ventral surface of the medulla that includes the retrotrapezoid nucleus (RTN), a central chemosensitive area, and the rostral ventrolateral medulla (RVLM). Although the mechanisms and pathways activated by leptin to facilitate breathing are still not completely clear, evidence suggests that the facilitatory effects of leptin on breathing require the brain melanocortin system, including the POMC-MC4R pathway, a mechanism also activated by leptin to modulate blood pressure. The results of all the studies that have investigated the effect of leptin on breathing suggest that disruption of leptin signalling as caused by obesity-induced reduction of central leptin function (leptin resistance) is a relevant mechanism that may contribute to respiratory dysfunctions associated with obesity.
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Affiliation(s)
- M. Bassi
- Department of Physiology and Pathology, School of DentistrySão Paulo State University (UNESP)AraraquaraSPBrazil
| | - W. I. Furuya
- Department of Physiology and Pathology, School of DentistrySão Paulo State University (UNESP)AraraquaraSPBrazil
| | - D. B. Zoccal
- Department of Physiology and Pathology, School of DentistrySão Paulo State University (UNESP)AraraquaraSPBrazil
| | - J. V. Menani
- Department of Physiology and Pathology, School of DentistrySão Paulo State University (UNESP)AraraquaraSPBrazil
| | - D. S. A. Colombari
- Department of Physiology and Pathology, School of DentistrySão Paulo State University (UNESP)AraraquaraSPBrazil
| | - D. K. Mulkey
- Department of Physiology and NeurobiologyUniversity of ConnecticutStorrsCTUSA
| | - E. Colombari
- Department of Physiology and Pathology, School of DentistrySão Paulo State University (UNESP)AraraquaraSPBrazil
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26
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Pho H, Hernandez AB, Arias RS, Leitner EB, Van Kooten S, Kirkness JP, Schneider H, Smith PL, Polotsky VY, Schwartz AR. The effect of leptin replacement on sleep-disordered breathing in the leptin-deficient ob/ob mouse. J Appl Physiol (1985) 2015; 120:78-86. [PMID: 26472867 DOI: 10.1152/japplphysiol.00494.2015] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 10/13/2015] [Indexed: 12/27/2022] Open
Abstract
Obese leptin-deficient (ob/ob) mice demonstrate defects in upper airway structural and neuromuscular control. We hypothesized that these defects predispose to upper airway obstruction during sleep, and improve with leptin administration. High-fidelity polysomnographic recordings were conducted to characterize sleep and breathing patterns in conscious, unrestrained ob/ob mice (23 wk, 67.2 ± 4.1 g, n = 13). In a parallel-arm crossover study, we compared responses to subcutaneous leptin (1 μg/h) vs. vehicle on respiratory parameters during NREM and REM sleep. Upper airway obstruction was defined by the presence of inspiratory airflow limitation (IFL), as characterized by an early inspiratory plateau in airflow at a maximum level (V̇Imax) with increasing effort. The severity of upper airway obstruction (V̇Imax) was assessed along with minute ventilation (V̇E), tidal volume (VT), respiratory rate (RR), inspiratory duty cycle, and mean inspiratory flow at each time point. IFL occurred more frequently in REM sleep (37.6 ± 0.2% vs. 1.1 ± 0.0% in NREM sleep, P < 0.001), and leptin did not alter its frequency. V̇Imax (3.7 ± 1.1 vs. 2.7 ± 0.8 ml/s, P < 0.001) and V̇E increased (55.4 ± 22.0 vs. 39.8 ± 16.4 ml/min, P < 0.001) with leptin vs. vehicle administration. The increase in V̇E was due to a significant increase in VT (0.20 ± 0.06 vs. 0.16 ± 0.05 ml, P < 0.01) rather than RR. Increases in V̇E were attributable to increases in mean inspiratory flow (2.5 ± 0.8 vs. 1.8 ± 0.6 ml/s, P < 0.001) rather than inspiratory duty cycle. Similar increases in V̇E and its components were observed in non-flow-limited breaths during NREM and REM sleep. These responses suggest that leptin stabilized pharyngeal patency and increased drive to both the upper airway and diaphragm during sleep.
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Affiliation(s)
- H Pho
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - A B Hernandez
- Department of Pulmonary, Critical Care, and Sleep Medicine, Mount Sinai Hospital, New York, New York
| | - R S Arias
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - E B Leitner
- University of Michigan Medical School, Ann Arbor, Michigan; and
| | - S Van Kooten
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - J P Kirkness
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - H Schneider
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - P L Smith
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - V Y Polotsky
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - A R Schwartz
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland;
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27
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Bassi M, Nakamura NB, Furuya WI, Colombari DSA, Menani JV, do Carmo JM, da Silva AA, Hall JE, Colombari E. Activation of the brain melanocortin system is required for leptin-induced modulation of chemorespiratory function. Acta Physiol (Oxf) 2015; 213:893-901. [PMID: 25207799 DOI: 10.1111/apha.12394] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 07/08/2014] [Accepted: 09/05/2014] [Indexed: 10/24/2022]
Abstract
UNLABELLED Melanocortin receptors (MC3/4R) mediate most of the metabolic and cardiovascular actions of leptin. AIM Here, we tested if MC4R also contributes to leptin's effects on respiratory function. METHODS After control measurements, male Holtzman rats received daily microinjections of leptin, SHU9119 (MC3/4R antagonist) or SHU9119 combined with leptin infused into the brain lateral ventricle for 7 days. On the 6th day of treatment, tidal volume (VT ), respiratory frequency (fR ) and pulmonary ventilation (VE ) were measured by whole-body plethysmography during normocapnia or hypercapnia (7% CO2 ). Baseline mean arterial pressure (MAP), heart rate (HR) and metabolic rate were also measured. VE , VT and fR were also measured in mice with leptin receptor deletion in the entire central nervous system (LepR/Nestin-cre) or only in proopiomelanocortin neurones (LepR/POMC-cre) and in MC4R knockout (MC4R(-/-) ) and wild-type mice. RESULTS Leptin (5 μg day(-1) ) reduced body weight (~17%) and increased ventilatory response to hypercapnia, whereas SHU9119 (0.6 nmol day(-1) ) increased body weight (~18%) and reduced ventilatory responses compared with control-PBS group (Lep: 2119 ± 90 mL min(-1) kg(-1) and SHU9119: 997 ± 67 mL min(-1) kg(-1) , vs. PBS: 1379 ± 91 mL min(-1) kg(-1) ). MAP increased after leptin treatment (130 ± 2 mmHg) compared to PBS (106 ± 3 mmHg) or SHU9119 alone (109 ± 3 mmHg). SHU9119 prevented the effects of leptin on body weight, MAP (102 ± 3 mmHg) and ventilatory response to hypercapnia (1391 ± 137 mL min(-1) kg(-1) ). The ventilatory response to hypercapnia was attenuated in the LepR/Nestin-cre, LepR/POMC-cre and MC4R(-/-) mice. CONCLUSION These results suggest that central MC4R mediate the effects of leptin on respiratory response to hypercapnia.
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Affiliation(s)
- M. Bassi
- Department of Physiology and Pathology; School of Dentistry; São Paulo State University (UNESP); Araraquara Brazil
| | - N. B. Nakamura
- Department of Physiology and Pathology; School of Dentistry; São Paulo State University (UNESP); Araraquara Brazil
| | - W. I. Furuya
- Department of Physiology and Pathology; School of Dentistry; São Paulo State University (UNESP); Araraquara Brazil
| | - D. S. A. Colombari
- Department of Physiology and Pathology; School of Dentistry; São Paulo State University (UNESP); Araraquara Brazil
| | - J. V. Menani
- Department of Physiology and Pathology; School of Dentistry; São Paulo State University (UNESP); Araraquara Brazil
| | - J. M. do Carmo
- Department of Physiology and Biophysics; University of Mississippi Medical Center; Jackson MS USA
| | - A. A. da Silva
- Department of Physiology and Biophysics; University of Mississippi Medical Center; Jackson MS USA
| | - J. E. Hall
- Department of Physiology and Biophysics; University of Mississippi Medical Center; Jackson MS USA
| | - E. Colombari
- Department of Physiology and Pathology; School of Dentistry; São Paulo State University (UNESP); Araraquara Brazil
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28
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Bassi M, Furuya WI, Zoccal DB, Menani JV, Colombari E, Hall JE, da Silva AA, do Carmo JM, Colombari DSA. Control of respiratory and cardiovascular functions by leptin. Life Sci 2015; 125:25-31. [PMID: 25645056 PMCID: PMC4355938 DOI: 10.1016/j.lfs.2015.01.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 12/19/2014] [Accepted: 01/23/2015] [Indexed: 01/29/2023]
Abstract
Leptin, a peptide hormone produced by adipose tissue, acts in brain centers that control critical physiological functions such as metabolism, breathing and cardiovascular regulation. The importance of leptin for respiratory control is evident by the fact that leptin deficient mice exhibit impaired ventilatory responses to carbon dioxide (CO2), which can be corrected by intracerebroventricular leptin replacement therapy. Leptin is also recognized as an important link between obesity and hypertension. Humans and animal models lacking either leptin or functional leptin receptors exhibit many characteristics of the metabolic syndrome, including hyperinsulinemia, insulin resistance, hyperglycemia, dyslipidemia and visceral adiposity, but do not exhibit increased sympathetic nerve activity (SNA) and have normal to lower blood pressure (BP) compared to lean controls. Even though previous studies have extensively focused on the brain sites and intracellular signaling pathways involved in leptin effects on food intake and energy balance, the mechanisms that mediate the actions of leptin on breathing and cardiovascular function are only beginning to be elucidated. This mini-review summarizes recent advances on the effects of leptin on cardiovascular and respiratory control with emphasis on the neural control of respiratory function and autonomic activity.
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Affiliation(s)
- M Bassi
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil.
| | - W I Furuya
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - D B Zoccal
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - J V Menani
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - E Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - J E Hall
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA
| | - A A da Silva
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA
| | - J M do Carmo
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA
| | - D S A Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
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29
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Ciriello J, Caverson MM. Carotid chemoreceptor afferent projections to leptin receptor containing neurons in nucleus of the solitary tract. Peptides 2014; 58:30-5. [PMID: 24905621 DOI: 10.1016/j.peptides.2014.05.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 05/26/2014] [Accepted: 05/27/2014] [Indexed: 11/23/2022]
Abstract
Neurons expressing the leptin receptor (Ob-R) exist within the caudal nucleus of the solitary tract (NTS). Additionally, afferent neurons expressing the Ob-R have been identified within the nodose ganglion and NTS. Furthermore, systemic injections or focal injections of leptin directly into NTS potentiate the response of NTS neurons to carotid chemoreceptor activation. However, the distribution of carotid body afferents in relation to Ob-R containing neurons within NTS is not known. In this study, chemoreceptor afferent fibers were labeled following microinjection of the anterograde tract tracer biotinylated dextran amine (BDA) into the carotid body or petrosal/nodose ganglion of Wistar rats. After a survival period of 10-14 days, the NTS was processed for BDA and Ob-R immunoreactivity. Afferent axons originating in the carotid body were found to project to the lateral (Slt), gelantinosa (Sg), and medial (Sm) subnuclei of the NTS complex. A similar, but more robust distribution of BDA labeled fibers was observed in the NTS complex after injections into the petrosal/nodose ganglion. Carotid body BDA labeled fibers were observed in close apposition to Ob-R immunoreactive neurons in the region of Slt, Sg and Sm. In addition, a small number of carotid body afferents were found to contain both BDA and express Ob-R-like immunoreactivity within the regions of Slt, Sg and Sm. Taken together, these data suggest that leptin may modulate carotid chemoreceptor function not only through direct effects on NTS neurons, but also through a direct effect on carotid body primary afferent fibers that innervate NTS neurons.
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Affiliation(s)
- John Ciriello
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada N6A 5C1.
| | - Monica M Caverson
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada N6A 5C1
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Zoccal DB, Furuya WI, Bassi M, Colombari DSA, Colombari E. The nucleus of the solitary tract and the coordination of respiratory and sympathetic activities. Front Physiol 2014; 5:238. [PMID: 25009507 PMCID: PMC4070480 DOI: 10.3389/fphys.2014.00238] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 06/09/2014] [Indexed: 12/15/2022] Open
Abstract
It is well known that breathing introduces rhythmical oscillations in the heart rate and arterial pressure levels. Sympathetic oscillations coupled to the respiratory activity have been suggested as an important homeostatic mechanism optimizing tissue perfusion and blood gas uptake/delivery. This respiratory-sympathetic coupling is strengthened in conditions of blood gas challenges (hypoxia and hypercapnia) as a result of the synchronized activation of brainstem respiratory and sympathetic neurons, culminating with the emergence of entrained cardiovascular and respiratory reflex responses. Studies have proposed that the ventrolateral region of the medulla oblongata is a major site of synaptic interaction between respiratory and sympathetic neurons. However, other brainstem regions also play a relevant role in the patterning of respiratory and sympathetic motor outputs. Recent findings suggest that the neurons of the nucleus of the solitary tract (NTS), in the dorsal medulla, are essential for the processing and coordination of respiratory and sympathetic responses to hypoxia. The NTS is the first synaptic station of the cardiorespiratory afferent inputs, including peripheral chemoreceptors, baroreceptors and pulmonary stretch receptors. The synaptic profile of the NTS neurons receiving the excitatory drive from afferent inputs is complex and involves distinct neurotransmitters, including glutamate, ATP and acetylcholine. In the present review we discuss the role of the NTS circuitry in coordinating sympathetic and respiratory reflex responses. We also analyze the neuroplasticity of NTS neurons and their contribution for the development of cardiorespiratory dysfunctions, as observed in neurogenic hypertension, obstructive sleep apnea and metabolic disorders.
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Affiliation(s)
- Daniel B Zoccal
- Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University (UNESP) Araraquara, Brazil
| | - Werner I Furuya
- Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University (UNESP) Araraquara, Brazil
| | - Mirian Bassi
- Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University (UNESP) Araraquara, Brazil
| | - Débora S A Colombari
- Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University (UNESP) Araraquara, Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University (UNESP) Araraquara, Brazil
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Bassi M, Furuya WI, Menani JV, Colombari DSA, do Carmo JM, da Silva AA, Hall JE, Moreira TS, Wenker IC, Mulkey DK, Colombari E. Leptin into the ventrolateral medulla facilitates chemorespiratory response in leptin-deficient (ob/ob) mice. Acta Physiol (Oxf) 2014; 211:240-8. [PMID: 24521430 PMCID: PMC4365783 DOI: 10.1111/apha.12257] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 01/18/2014] [Accepted: 02/07/2014] [Indexed: 12/27/2022]
Abstract
AIM Leptin, an adipocyte-derived hormone, is suggested to participate in the central control of breathing. We hypothesized that leptin may facilitate ventilatory responses to chemoreflex activation by acting on respiratory nuclei of the ventrolateral medulla. The baseline ventilation and the ventilatory responses to CO2 were evaluated before and after daily injections of leptin into the retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG) for 3 days in obese leptin-deficient (ob/ob) mice. METHODS Male ob/ob mice (40-45 g, n = 7 per group) received daily microinjections of vehicle or leptin (1 μg per 100 nL) for 3 days into the RTN/pFRG. Respiratory responses to CO2 were measured by whole-body plethysmography. RESULTS Unilateral microinjection of leptin into the RTN/pFRG in ob/ob mice increased baseline ventilation (VE ) from 1447 ± 96 to 2405 ± 174 mL min(-1) kg(-1) by increasing tidal volume (VT ) from 6.4 ± 0.4 to 9.1 ± 0.8 mL kg(-1) (P < 0.05). Leptin also enhanced ventilatory responses to 7% CO2 (Δ = 2172 ± 218 mL min(-1) kg(-1) , vs. control: Δ = 1255 ± 105 mL min(-1) kg(-1) ), which was also due to increased VT (Δ = 4.71 ± 0.51 mL kg(-1) , vs. control: Δ = 2.27 ± 0.20 mL kg(-1) ), without changes in respiratory frequency. Leptin treatment into the RTN/pFRG or into the surrounding areas decreased food intake (83 and 70%, respectively), without significantly changing body weight. CONCLUSION The present results suggest that leptin acting in the respiratory nuclei of the ventrolateral medulla improves baseline VE and VT and facilitates respiratory responses to hypercapnia in ob/ob mice.
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Affiliation(s)
- M. Bassi
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - W. I. Furuya
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - J. V. Menani
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - D. S. A. Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - J. M. do Carmo
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA
| | - A. A. da Silva
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA
| | - J. E. Hall
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA
| | - T. S. Moreira
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of São Paulo (USP), São Paulo, SP, Brazil
| | - I. C. Wenker
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - D. K. Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - E. Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
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Chang Z, Ballou E, Jiao W, McKenna KE, Morrison SF, McCrimmon DR. Systemic leptin produces a long-lasting increase in respiratory motor output in rats. Front Physiol 2013; 4:16. [PMID: 23408476 PMCID: PMC3569609 DOI: 10.3389/fphys.2013.00016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 01/22/2013] [Indexed: 11/21/2022] Open
Abstract
Leptin decreases food intake and increases energy expenditure. Leptin administration into the CNS of mice or rats increases alveolar ventilation and dysfunction in leptin signaling has been implicated in the hypoventilation that can accompany obesity. An increase in CO2 chemosensitivity has been implicated in this response but it is unclear whether ventilation is augmented when PCO2 is maintained constant. We examined the effects of intravenous leptin to test the hypothesis that systemic leptin administration in isoflurane anesthetized, mechanically ventilated and vagotomized rats would lead to a sustained increase in respiratory motor output that was independent of changes in end-tidal PCO2, body temperature or lung inflation pressure (an indicator of overall lung and chest wall compliance). In anesthetized Sprague-Dawley rats with end-tidal PCO2, lung compliance and rectal temperature maintained constant, injection of a bolus of leptin (0.25 mg, 0.5 mg/ml, i.v.), followed over the next 1 h by the intravenous infusion of an additional 0.25 mg, elicited a progressive increase in the peak amplitude of integrated phrenic nerve discharge lasting at least 1 h beyond the end of the infusion. The increase peaked at 90 min at 58.3 ± 5.7% above baseline. There was an associated increase in the slope of the phrenic response to increasing inspired CO2. There was also a moderate and sustained decrease in arterial pressure 9 ± 1.3 mmHg at 120 min, with no associated change in heart rate. These data indicate that leptin elicits a sustained increase in respiratory motor output that outlasts the administration leptin via a mechanism that does not require alterations in arterial PCO2, body temperature, or systemic afferent feedback via the vagus nerves. This stimulation may help to prevent obesity-related hypoventilation.
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Affiliation(s)
- Zheng Chang
- Department of Physiology, Feinberg School of Medicine, Northwestern University Chicago, IL, USA
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