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Koucký V, Koucká P, Koucký M. Hyperoxic ventilatory response in infants is related to nocturnal hypoxaemia. ERJ Open Res 2024; 10:00512-2023. [PMID: 38333650 PMCID: PMC10851931 DOI: 10.1183/23120541.00512-2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 10/22/2023] [Indexed: 02/10/2024] Open
Abstract
Background The carotid bodies primarily serve as oxaemia sensors that affect tidal breathing. Their function has not yet been studied in infants with nocturnal hypoxaemia. This cross-sectional study aimed to characterise the hyperoxic ventilatory response (HVR) in infants and its relationship to nocturnal hypoxaemia. Methods The HVR was analysed in term infants aged <24 months with childhood interstitial lung disease (chILD), those with severe recurrent wheezing (wheeze), and nonrespiratory controls. The HVR timing was characterised using hyperoxia response time (HRT1), and HVR magnitude was characterised by the relative change in minute volume between normoxia and 30-s hyperoxia (VE_dH30). Time spent with an arterial haemoglobin oxygen saturation (SpO2) <90% during overnight monitoring (t90) was estimated. Results HVR data were available for 23 infants with chILD, 24 wheeze and 14 control infants. A significant decrease in minute volume under 30 s of hyperoxia was observed in all patients. HRT1 was shorter in chILD (5.6±1.2 s) and wheeze (5.9±1.5 s) groups than in the controls (12.6±5.5 s) (ANOVA p<0.001). VE_dH30 was increased in the chILD group (24.3±8.0%) compared with that in the controls (14.7±9.2%) (p=0.003). t90 was abnormal in the wheeze (8.0±5.0%) and chILD (32.7±25.8%) groups and higher in the chILD group than in the controls (p<0.001). HRT1 negatively correlated with t90 in all groups. Conclusion Significant differences in HVR timing and magnitude were noted in the chILD, wheeze and control groups. A relationship between nocturnal hypoxaemia and HRT1 was proposed. HVR characterisation may help identify patients with abnormal nocturnal SpO2.
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Affiliation(s)
- Václav Koucký
- Department of Paediatrics, 2nd Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Pavlína Koucká
- Department of Paediatrics, 2nd Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Miroslav Koucký
- Department of Mathematics, Faculty of Science, Humanities and Education, Technical University of Liberec, Liberec, Czech Republic
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2
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Lazarov NE, Atanasova DY. Carotid Body Dysfunction and Mechanisms of Disease. ADVANCES IN ANATOMY, EMBRYOLOGY, AND CELL BIOLOGY 2023; 237:123-138. [PMID: 37946080 DOI: 10.1007/978-3-031-44757-0_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
Emerging evidence shows that the carotid body (CB) dysfunction is implicated in various physiological and pathophysiological conditions. It has been revealed that the CB structure and neurochemical profile alter in certain human sympathetic-related and cardiometabolic diseases. Specifically, a tiny CB with a decrease of glomus cells and their dense-cored vesicles has been seen in subjects with sleep disordered breathing such as sudden infant death syndrome and obstructive sleep apnea patients and people with congenital central hypoventilation syndrome. Moreover, the CB degranulation is accompanied by significantly elevated levels of catecholamines and proinflammatory cytokines in such patients. The intermittent hypoxia stimulates the CB, eliciting augmented chemoreflex drive and enhanced cardiorespiratory and sympathetic responses. High CB excitability due to blood flow restrictions, oxidative stress, alterations in neurotransmitter gases and disruptions of local mediators is also observed in congestive heart failure conditions. On the other hand, the morpho-chemical changes in hypertension include an increase in the CB volume due to vasodilation, altered transmitter phenotype of chemoreceptor cells and elevated production of neurotrophic factors. Accordingly, in both humans and animal models CB denervation prevents the breathing instability and lowers blood pressure. Knowledge of the morphofunctional aspects of the CB, a better understanding of its role in disease and recent advances in human CB translational research would contribute to the development of new therapeutic strategies.
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Affiliation(s)
- Nikolai E Lazarov
- Department of Anatomy and Histology, Faculty of Medicine, Medical University of Sofia, Sofia, Bulgaria.
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3
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Rakoczy RJ, Schiebrel CM, Wyatt CN. Acute Oxygen-Sensing via Mitochondria-Generated Temperature Transients in Rat Carotid Body Type I Cells. Front Physiol 2022; 13:874039. [PMID: 35510145 PMCID: PMC9060449 DOI: 10.3389/fphys.2022.874039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 03/28/2022] [Indexed: 12/28/2022] Open
Abstract
The Carotid Bodies (CB) are peripheral chemoreceptors that detect changes in arterial oxygenation and, via afferent inputs to the brainstem, correct the pattern of breathing to restore blood gas homeostasis. Herein, preliminary evidence is presented supporting a novel oxygen-sensing hypothesis which suggests CB Type I cell “hypoxic signaling” may in part be mediated by mitochondria-generated thermal transients in TASK-channel-containing microdomains. Distances were measured between antibody-labeled mitochondria and TASK-potassium channels in primary rat CB Type I cells. Sub-micron distance measurements (TASK-1: 0.33 ± 0.04 µm, n = 47 vs TASK-3: 0.32 ± 0.03 µm, n = 54) provided evidence for CB Type I cell oxygen-sensing microdomains. A temperature-sensitive dye (ERthermAC) indicated that inhibition of mitochondrial activity in isolated cells caused a rapid and reversible inhibition of mitochondrial thermogenesis and thus temperature in these microdomains. Whole-cell perforated-patch current-clamp electrophysiological recordings demonstrated sensitivity of resting membrane potential (Vm) to temperature: lowering bath temperature from 37°C to 24°C induced consistent and reversible depolarizations (Vm at 37°C: 48.4 ± 4.11 mV vs 24°C: 31.0 ± 5.69 mV; n = 5; p < 0.01). These data suggest that hypoxic inhibition of mitochondrial thermogenesis may play an important role in oxygen chemotransduction in the CB. A reduction in temperature within cellular microdomains will inhibit plasma membrane ion channels, influence the balance of cellular phosphorylation–dephosphorylation, and may extend the half-life of reactive oxygen species. The characterization of a thermosensory chemotransduction mechanism, that may also be used by other oxygen-sensitive cell types and may impact multiple other chemotransduction mechanisms is critical if we are to fully understand how the CBs, and potentially other oxygen-sensitive cells, respond to hypoxia.
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Abstract
The carotid body (CB) is a bilateral arterial chemoreceptor located in the carotid artery bifurcation with an essential role in cardiorespiratory homeostasis. It is composed of highly perfused cell clusters, or glomeruli, innervated by sensory fibers. Glomus cells, the most abundant in each glomerulus, are neuron-like multimodal sensory elements able to detect and integrate changes in several physical and chemical parameters of the blood, in particular O2 tension, CO2 and pH, as well as glucose, lactate, or blood flow. Activation of glomus cells (e.g., during hypoxia or hypercapnia) stimulates the afferent fibers which impinge on brainstem neurons to elicit rapid compensatory responses (hyperventilation and sympathetic activation). This chapter presents an updated view of the structural organization of the CB and the mechanisms underlying the chemosensory responses of glomus cells, with special emphasis on the molecular processes responsible for acute O2 sensing. The properties of the glomus cell-sensory fiber synapse as well as the organization of CB output are discussed. The chapter includes the description of recently discovered CB stem cells and progenitor cells, and their role in CB growth during acclimatization to hypoxemia. Finally, the participation of the CB in the mechanisms of disease is briefly discussed.
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Affiliation(s)
- José López-Barneo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Sevilla, Seville, Spain; Biomedical Research Center for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.
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5
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Iturriaga R, Alcayaga J, Chapleau MW, Somers VK. Carotid body chemoreceptors: physiology, pathology, and implications for health and disease. Physiol Rev 2021; 101:1177-1235. [PMID: 33570461 PMCID: PMC8526340 DOI: 10.1152/physrev.00039.2019] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The carotid body (CB) is the main peripheral chemoreceptor for arterial respiratory gases O2 and CO2 and pH, eliciting reflex ventilatory, cardiovascular, and humoral responses to maintain homeostasis. This review examines the fundamental biology underlying CB chemoreceptor function, its contribution to integrated physiological responses, and its role in maintaining health and potentiating disease. Emphasis is placed on 1) transduction mechanisms in chemoreceptor (type I) cells, highlighting the role played by the hypoxic inhibition of O2-dependent K+ channels and mitochondrial oxidative metabolism, and their modification by intracellular molecules and other ion channels; 2) synaptic mechanisms linking type I cells and petrosal nerve terminals, focusing on the role played by the main proposed transmitters and modulatory gases, and the participation of glial cells in regulation of the chemosensory process; 3) integrated reflex responses to CB activation, emphasizing that the responses differ dramatically depending on the nature of the physiological, pathological, or environmental challenges, and the interactions of the chemoreceptor reflex with other reflexes in optimizing oxygen delivery to the tissues; and 4) the contribution of enhanced CB chemosensory discharge to autonomic and cardiorespiratory pathophysiology in obstructive sleep apnea, congestive heart failure, resistant hypertension, and metabolic diseases and how modulation of enhanced CB reactivity in disease conditions may attenuate pathophysiology.
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Affiliation(s)
- Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile, and Centro de Excelencia en Biomedicina de Magallanes, Universidad de Magallanes, Punta Arenas, Chile
| | - Julio Alcayaga
- Laboratorio de Fisiología Celular, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Mark W Chapleau
- Department of Internal Medicine, University of Iowa and Department of Veterans Affairs Medical Center, Iowa City, Iowa
| | - Virend K Somers
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
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Ortega-Sáenz P, Moreno-Domínguez A, Gao L, López-Barneo J. Molecular Mechanisms of Acute Oxygen Sensing by Arterial Chemoreceptor Cells. Role of Hif2α. Front Physiol 2020; 11:614893. [PMID: 33329066 PMCID: PMC7719705 DOI: 10.3389/fphys.2020.614893] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 11/03/2020] [Indexed: 01/28/2023] Open
Abstract
Carotid body glomus cells are multimodal arterial chemoreceptors able to sense and integrate changes in several physical and chemical parameters in the blood. These cells are also essential for O2 homeostasis. Glomus cells are prototypical peripheral O2 sensors necessary to detect hypoxemia and to elicit rapid compensatory responses (hyperventilation and sympathetic activation). The mechanisms underlying acute O2 sensing by glomus cells have been elusive. Using a combination of mouse genetics and single-cell optical and electrophysiological techniques, it has recently been shown that activation of glomus cells by hypoxia relies on the generation of mitochondrial signals (NADH and reactive oxygen species), which modulate membrane ion channels to induce depolarization, Ca2+ influx, and transmitter release. The special sensitivity of glomus cell mitochondria to changes in O2 tension is due to Hif2α-dependent expression of several atypical mitochondrial subunits, which are responsible for an accelerated oxidative metabolism and the strict dependence of mitochondrial complex IV activity on O2 availability. A mitochondrial-to-membrane signaling model of acute O2 sensing has been proposed, which explains existing data and provides a solid foundation for future experimental tests. This model has also unraveled new molecular targets for pharmacological modulation of carotid body activity potentially relevant in the treatment of highly prevalent medical conditions.
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Affiliation(s)
- Patricia Ortega-Sáenz
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain.,Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Alejandro Moreno-Domínguez
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain.,Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
| | - Lin Gao
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain.,Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - José López-Barneo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain.,Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
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Bednarczuk N, Milner A, Greenough A. The Role of Maternal Smoking in Sudden Fetal and Infant Death Pathogenesis. Front Neurol 2020; 11:586068. [PMID: 33193050 PMCID: PMC7644853 DOI: 10.3389/fneur.2020.586068] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 09/14/2020] [Indexed: 12/18/2022] Open
Abstract
Maternal smoking is a risk factor for both sudden infant death syndrome (SIDS) and sudden intrauterine unexplained death syndrome (SIUDS). Both SIDS and SIUDS are more frequently observed in infants of smoking mothers. The global prevalence of smoking during pregnancy is 1.7% and up to 8.1% of women in Europe smoke during pregnancy and worldwide 250 million women smoke during pregnancy. Infants born to mothers who smoke have an abnormal response to hypoxia and hypercarbia and they also have reduced arousal responses. The harmful effects of tobacco smoke are mainly mediated by release of carbon monoxide and nicotine. Nicotine can enter the fetal circulation and affect multiple developing organs including the lungs, adrenal glands and the brain. Abnormalities in brainstem nuclei crucial to respiratory control, the cerebral cortex and the autonomic nervous system have been demonstrated. In addition, hypodevelopment of the intermediolateral nucleus in the spinal cord has been reported. It initiates episodic respiratory movements that facilitate lung development. Furthermore, abnormal maturation and transmitter levels in the carotid bodies have been described which would make infants more vulnerable to hypoxic challenges. Unfortunately, smoking cessation programs do not appear to have significantly reduced the number of pregnant women who smoke.
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Affiliation(s)
- Nadja Bednarczuk
- Department of Women and Children's Health, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, London, United Kingdom
| | - Anthony Milner
- Department of Women and Children's Health, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, London, United Kingdom
| | - Anne Greenough
- Department of Women and Children's Health, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, London, United Kingdom.,The Asthma UK Centre for Allergic Mechanisms of Asthma, King's College London, London, United Kingdom.,National Institute for Health Research (NIHR) Biomedical Research Centre at Guy's & St Thomas' National Health Service (NHS) Foundation Trust and King's College London, London, United Kingdom
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8
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Blood and urine biomarkers associated with long-term respiratory dysfunction following neonatal hyperoxia exposure: Implications for prematurity and risk of SIDS. Respir Physiol Neurobiol 2020; 279:103465. [PMID: 32450147 DOI: 10.1016/j.resp.2020.103465] [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: 02/28/2020] [Revised: 05/06/2020] [Accepted: 05/20/2020] [Indexed: 12/15/2022]
Abstract
Former preterm infants, many of whom required supplemental O2 support, exhibit sleep disordered breathing and attenuated ventilatory responses to acute hypoxia (HVR) beyond their NICU stay. There is an increasing awareness that early detection of biomarkers in biological fluids may be useful predictors/identifiers of short- and long-term morbidities. In the present study, we identified serotonin (5-HT), dopamine (DA) and hyaluronan (HA) as three potential biomarkers that may be increased by neonatal hyperoxia and tested whether they would be associated with an impaired HVR in a rat model of supplemental O2 exposure. Neonatal rats (postnatal age (P) 6 days, P6) exposed to hyperoxia (40% FIO2, 24 h/day between P1-P5 days of age) exhibited an attenuated early (1 min), but not the late (4-5 min) phase of the HVR compared to normoxia control rats; the attenuated early phase HVR was associated with increased levels of DA (urine and serum), 5-HT (platelet poor plasma only, PPP), and HA (serum only). At P21, both the early and late phases of the HVR were attenuated, but serum and urine levels of all 3 biomarkers were similar to age-matched control rats. These data indicate that changes in several serum and/or urine biomarkers (5-HT, DA, and HA) following short-term (days) neonatal hyperoxia can signify long-term (weeks) respiratory control dysfunction. Further studies are needed to determine whether early detection of similar biomarkers could be convenient predictors of increased risk of abnormalities in respiratory control including sleep disordered breathing in former preterm infants who had received prior supplemental O2 and who might also be at increased risk of SIDS.
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9
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Ventilatory and carotid body responses to acute hypoxia in rats exposed to chronic hypoxia during the first and second postnatal weeks. Respir Physiol Neurobiol 2020; 275:103400. [PMID: 32006667 DOI: 10.1016/j.resp.2020.103400] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 12/20/2019] [Accepted: 01/27/2020] [Indexed: 01/24/2023]
Abstract
Chronic hypoxia (CH) during postnatal development causes a blunted hypoxic ventilatory response (HVR) in neonatal mammals. The magnitude of the HVR generally increases with age, so CH could blunt the HVR by delaying this process. Accordingly, we predicted that CH would have different effects on the respiratory control of neonatal rats if initiated at birth versus initiated later in postnatal development (i.e., after the HVR has had time to mature). Rats had blunted ventilatory and carotid body responses to hypoxia whether CH (12 % O2) occurred for the first postnatal week (P0 to P7) or second postnatal week (P7 to P14). However, if initiated at P0, CH also caused the HVR to retain the "biphasic" shape characteristic of newborn mammals; CH during the second postnatal week did not result in a biphasic HVR. CH from birth delayed the transition from a biphasic HVR to a sustained HVR until at least P9-11, but the HVR attained a sustained (albeit blunted) phenotype by P13-15. Since delayed maturation of the HVR did not completely explain the blunted HVR, we tested the alternative hypothesis that the blunted HVR was caused by an inflammatory response to CH. Daily administration of the anti-inflammatory drug ibuprofen (4 mg kg-1, i.p.) did not alter the effects of CH on the HVR. Collectively, these data suggest that CH blunts the HVR in neonatal rats by impairing carotid body responses to hypoxia and by delaying (but not preventing) postnatal maturation of the biphasic HVR. The mechanisms underlying this plasticity require further investigation.
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10
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Zera T, Moraes DJA, da Silva MP, Fisher JP, Paton JFR. The Logic of Carotid Body Connectivity to the Brain. Physiology (Bethesda) 2020; 34:264-282. [PMID: 31165684 DOI: 10.1152/physiol.00057.2018] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The carotid body has emerged as a therapeutic target for cardio-respiratory-metabolic diseases. With the expansive functions of the chemoreflex, we sought mechanisms to explain differential control of individual responses. We purport a remarkable correlation between phenotype of a chemosensory unit (glomus cell-sensory afferent) with a distinct component of the reflex response. This logic could permit differential modulation of distinct chemoreflex responses, a strategy ideal for therapeutic exploitation.
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Affiliation(s)
- Tymoteusz Zera
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw , Warsaw , Poland
| | - Davi J A Moraes
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo , São Paulo , Brazil
| | - Melina P da Silva
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo , São Paulo , Brazil
| | - James P Fisher
- Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland , Auckland , New Zealand
| | - Julian F R Paton
- Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland , Auckland , New Zealand
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11
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Barrett KT, Hasan SU, Scantlebury MH, Wilson RJA. Impaired neonatal cardiorespiratory responses to hypoxia in mice lacking PAC1 or VPAC2 receptors. Am J Physiol Regul Integr Comp Physiol 2019; 316:R594-R606. [PMID: 30758978 DOI: 10.1152/ajpregu.00250.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The stress peptide pituitary adenylate cyclase activating polypeptide (PACAP) and its specific receptor PACAP type 1 receptor (PAC1) have been implicated in sudden infant death syndrome (SIDS). PACAP is also critical to the neonatal cardiorespiratory response to homeostatic stressors identified in SIDS, including hypoxia. However, which of PACAP's three receptors, PAC1, vasoactive intestinal peptide receptor type 1 (VPAC1), and/or vasoactive intestinal peptide receptor type 2 (VPAC2), are involved is unknown. In this study, we hypothesized that PAC1, but not VPAC2, is involved in mediating the cardiorespiratory response to hypoxia during neonatal development. To test this hypothesis, head-out plethysmography and surface ECG electrodes were used to assess the cardiorespiratory variables of unanesthetized postnatal day 4 PAC1 and VPAC2-knockout (KO) and wild-type (WT) mice in response to a 10% hypoxic challenge. Our results demonstrate that compared with WT pups, the early and late hypoxic rate of expired CO2 (V̇co2), V̇co2 and ventilatory responses were blunted in PAC1-KO neonates, and during the posthypoxic period, minute ventilation (V̇e), V̇co2 and heart rate were increased, while the increase in apneas normally associated with the posthypoxic period was reduced. Consistent with impaired cardiorespiratory control in these animals, the V̇e/V̇co2 slope was reduced in PAC1-KO pups, suggesting that breathing was inappropriately matched to metabolism. In contrast, VPAC2-KO pups exhibited elevated heart rate variability during hypoxia compared with WT littermates, but the effects of the VPAC2-KO genotype on breathing were minimal. These findings suggest that PAC1 plays the principal role in mediating the cardiorespiratory effects of PACAP in response to hypoxic stress during neonatal development and that defective PACAP signaling via PAC1 may contribute to the pathogenesis of SIDS.
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Affiliation(s)
- Karlene T Barrett
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, University of Calgary , Calgary, Alberta , Canada
| | - Shabih U Hasan
- Department of Pediatrics, Alberta Children's Hospital Research Institute, University of Calgary , Calgary, Alberta , Canada
| | - Morris H Scantlebury
- Department of Pediatrics, Clinical Neuroscience, Alberta Children's Hospital Research Institute, University of Calgary , Calgary, Alberta , Canada
| | - Richard J A Wilson
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, University of Calgary , Calgary, Alberta , Canada
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12
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Sobrino V, Annese V, Pardal R. Progenitor Cell Heterogeneity in the Adult Carotid Body Germinal Niche. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1123:19-38. [PMID: 31016593 DOI: 10.1007/978-3-030-11096-3_3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Somatic stem cells confer plasticity to adult tissues, permitting their maintenance, repair and adaptation to a changing environment. Adult germinal niches supporting somatic stem cells have been thoroughly characterized throughout the organism, including in central and peripheral nervous systems. Stem cells do not reside alone within their niches, but they are rather accompanied by multiple progenitor cells that not only contribute to the progression of stem cell lineage but also regulate their behavior. Understanding the mechanisms underlying these interactions within the niche is crucial to comprehend associated pathologies and to use stem cells in cell therapy. We have described a stunning germinal niche in the adult peripheral nervous system: the carotid body. This is a chemoreceptor organ with a crucial function during physiological adaptation to hypoxia. We have shown the presence of multipotent stem cells within this niche, escorted by multiple restricted progenitor cell types that contribute to niche physiology and hence organismal adaptation to the lack of oxygen. Herein, we discuss new and existing data about the nature of all these stem and progenitor cell types present in the carotid body germinal niche, discussing their role in physiology and their clinical relevance for the treatment of diverse pathologies.
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Affiliation(s)
- Verónica Sobrino
- Dpto. de Fisiología Médica y Biofísica, Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - Valentina Annese
- Dpto. de Fisiología Médica y Biofísica, Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - Ricardo Pardal
- Dpto. de Fisiología Médica y Biofísica, Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain.
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Porzionato A, Macchi V, De Caro R. Central and peripheral chemoreceptors in sudden infant death syndrome. J Physiol 2018; 596:3007-3019. [PMID: 29645275 PMCID: PMC6068209 DOI: 10.1113/jp274355] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 03/20/2018] [Indexed: 11/08/2022] Open
Abstract
The pathogenesis of sudden infant death syndrome (SIDS) has been ascribed to an underlying biological vulnerability to stressors during a critical period of development. This paper reviews the main data in the literature supporting the role of central (e.g. retrotrapezoid nucleus, serotoninergic raphe nuclei, locus coeruleus, orexinergic neurons, ventral medullary surface, solitary tract nucleus) and peripheral (e.g. carotid body) chemoreceptors in the pathogenesis of SIDS. Clinical and experimental studies indicate that central and peripheral chemoreceptors undergo critical development during the initial postnatal period, consistent with the age range of SIDS (<1 year). Most of the risk factors for SIDS (gender, genetic factors, prematurity, hypoxic/hyperoxic stimuli, inflammation, perinatal exposure to cigarette smoke and/or substance abuse) may structurally and functionally affect the developmental plasticity of central and peripheral chemoreceptors, strongly suggesting the involvement of these structures in the pathogenesis of SIDS. Morphometric and neurochemical changes have been found in the carotid body and brainstem respiratory chemoreceptors of SIDS victims, together with functional signs of chemoreception impairment in some clinical studies. However, the methodological problems of SIDS research will have to be addressed in the future, requiring large and highly standardized case series. Up-to-date autopsy protocols should be produced, involving substantial, and exhaustive sampling of all potentially involved structures (including peripheral arterial chemoreceptors). Morphometric approaches should include unbiased stereological methods with three-dimensional probes. Prospective clinical studies addressing functional tests and risk factors (including genetic traits) would probably be the gold standard, allowing markers of intrinsic or acquired vulnerability to be properly identified.
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Affiliation(s)
- Andrea Porzionato
- Section of Anatomy, Department of NeuroscienceUniversity of PadovaItaly
| | - Veronica Macchi
- Section of Anatomy, Department of NeuroscienceUniversity of PadovaItaly
| | - Raffaele De Caro
- Section of Anatomy, Department of NeuroscienceUniversity of PadovaItaly
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Porzionato A, Macchi V, Stecco C, De Caro R. The Carotid Sinus Nerve-Structure, Function, and Clinical Implications. Anat Rec (Hoboken) 2018; 302:575-587. [PMID: 29663677 DOI: 10.1002/ar.23829] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Revised: 06/24/2017] [Accepted: 08/01/2017] [Indexed: 12/12/2022]
Abstract
Interest has been renewed in the anatomy and physiology of the carotid sinus nerve (CSN) and its targets (carotid sinus and carotid body, CB), due to recent proposals of surgical procedures for a series of common pathologies, such as carotid sinus syndrome, hypertension, heart failure, and insulin resistance. The CSN originates from the glossopharyngeal nerve soon after its appearance from the jugular foramen. It shows frequent communications with the sympathetic trunk (usually at the level of the superior cervical ganglion) and the vagal nerve (main trunk, pharyngeal branches, or superior laryngeal nerve). It courses on the anterior aspect of the internal carotid artery to reach the carotid sinus, CB, and/or intercarotid plexus. In the carotid sinus, type I (dynamic) carotid baroreceptors have larger myelinated A-fibers; type II (tonic) baroreceptors show smaller A- and unmyelinated C-fibers. In the CB, afferent fibers are mainly stimulated by acetylcholine and ATP, released by type I cells. The neurons are located in the petrosal ganglion, and centripetal fibers project on to the solitary tract nucleus: chemosensory inputs to the commissural subnucleus, and baroreceptor inputs to the commissural, medial, dorsomedial, and dorsolateral subnuclei. The baroreceptor component of the CSN elicits sympatho-inhibition and the chemoreceptor component stimulates sympatho-activation. Thus, in refractory hypertension and heart failure (characterized by increased sympathetic activity), baroreceptor electrical stimulation, and CB removal have been proposed. Instead, denervation of the carotid sinus has been proposed for the "carotid sinus syndrome." Anat Rec, 302:575-587, 2019. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Andrea Porzionato
- Department of Neuroscience, Institute of Human Anatomy, University of Padova, Padova, Italy
| | - Veronica Macchi
- Department of Neuroscience, Institute of Human Anatomy, University of Padova, Padova, Italy
| | - Carla Stecco
- Department of Neuroscience, Institute of Human Anatomy, University of Padova, Padova, Italy
| | - Raffaele De Caro
- Department of Neuroscience, Institute of Human Anatomy, University of Padova, Padova, Italy
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Varga I, Bódi I, Mešťanová V, Kováč M, Klein M. Association between histological alterations in the thymus and sudden infant death syndrome. J Forensic Leg Med 2018; 55:8-13. [PMID: 29438849 DOI: 10.1016/j.jflm.2018.02.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Revised: 02/01/2018] [Accepted: 02/07/2018] [Indexed: 12/23/2022]
Abstract
INTRODUCTION Sudden infant death syndrome (SIDS) involves the death of an infant during the first year of life and it is among the leading causes of infant mortality worldwide. One hypothesis regarding the pathogenesis of SIDS is that it results from a combination of three independent factors: endogenous vulnerability, a critical time window during postnatal development, and exogenous stressors. This hypothesis is known as the "triple-risk model". METHODS In this study, we used an immunohistological approach to compare the cellular microenvironments of thymuses from 19 infants whose sudden death was classified as SIDS and a control group, which consisted of thymuses from age-matched children undergoing surgery for various congenital heart defects. We hypothesized that morphological signs of stress-related thymic involution would be present. RESULTS Based on our observations, we found evidence that the proliferation and maturation of T-lymphocytes in the thymuses of infants with SIDS were suppressed. We observed enhanced macrophage activity, suggesting an increase in the apoptosis of lymphocytes and decrease in number of thymic dendritic cells and myoid cells. Significant apoptosis of thymic lymphocytes without cell regeneration typically leads to atrophy of the thymus. All cellular events we observed resemble the initial stage of stress-related thymic involution. CONCLUSION These results support the "triple-risk model," suggesting that certain exogenous stressors might be involved in the pathogenesis of SIDS. This was probably not recognized during the autopsies of infants who died suddenly.
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Affiliation(s)
- Ivan Varga
- Institute of Histology and Embryology, Faculty of Medicine, Comenius University, Bratislava, Slovakia.
| | - Ildikó Bódi
- Department of Anatomy, Histology, and Embryology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Veronika Mešťanová
- Institute of Histology and Embryology, Jessenius Faculty of Medicine, Comenius University, Martin, Slovakia
| | - Martin Kováč
- Department of Forensic Medicine, Health Care Surveillance Authority, Prešov, Slovakia
| | - Martin Klein
- Institute of Histology and Embryology, Faculty of Medicine, Comenius University, Bratislava, Slovakia
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Iturriaga R. Translating carotid body function into clinical medicine. J Physiol 2017; 596:3067-3077. [PMID: 29114876 DOI: 10.1113/jp275335] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 10/18/2017] [Indexed: 12/12/2022] Open
Abstract
The carotid body (CB) is considered the main O2 chemoreceptor, which contributes to cardiorespiratory homeostasis and ventilatory acclimatization. In clinical medicine, the most common pathologies associated with the CB are tumours. However, a growing body of evidence supports the novel idea that an enhanced CB chemosensory discharge contributes to the autonomic dysfunction and pathological consequences in obstructive sleep apnoea (OSA), hypertension, systolic heart failure (HF) and cardiometabolic diseases. Heightened CB chemosensory reactivity elicited by oxidative stress has been involved in sympathetic hyperactivity, cardiorespiratory instability, hypertension and insulin resistance. CB ablation, which reduces sympathetic hyperactivity, decreases hypertension in animal models of OSA and hypertension, eliminates breathing instability and improves animal survival in HF, and restores insulin tolerance in cardiometabolic models. Thus, data obtained from preclinical studies highlight the importance of the CB in the progression of sympathetic-related diseases, supporting the idea that appeasing the enhanced CB chemosensory drive may be useful in improving cardiovascular, respiratory and endocrine alterations. Accordingly, CB ablation has been proposed and used as a treatment for moderating resistant hypertension and HF-induced sympathetic hyperactivity in humans. First-in-human studies have shown that CB ablation reduces sympathetic overactivity, transiently reduces severe hypertension and improves quality of life in HF patients. Thus, CB ablation would be a useful therapy to reverse sympathetic overactivation in HF and severe hypertension, but caution is required before it is widely used due to the crucial physiological function played by the CB. Further studies in preclinical models are required to assess side-effects of CB ablation.
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Affiliation(s)
- Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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Sex-dependent differences in the in vivo respiratory phenotype of the TASK-1 potassium channel knockout mouse. Respir Physiol Neurobiol 2017; 245:13-28. [DOI: 10.1016/j.resp.2016.11.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Revised: 11/04/2016] [Accepted: 11/07/2016] [Indexed: 11/19/2022]
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Ramirez S, Allen T, Villagracia L, Chae Y, Ramirez JM, Rubens DD. Inner ear lesion and the differential roles of hypoxia and hypercarbia in triggering active movements: Potential implication for the Sudden Infant Death Syndrome. Neuroscience 2016; 337:9-16. [PMID: 27634772 DOI: 10.1016/j.neuroscience.2016.08.054] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 08/29/2016] [Accepted: 08/31/2016] [Indexed: 01/12/2023]
Abstract
Infants that succumb to Sudden Infant Death Syndrome (SIDS) have been identified with inner ear dysfunction (IED) at birth and on autopsy. We previously investigated whether IED could play a mechanistic role in SIDS. We discovered that animals with IED displayed significant suppression of movement arousal to a hypoxic-hypercarbic gas mixture under light anesthesia. In the current study we investigated the role of each gas in triggering movements and the response to hypercarbia during natural sleep without anesthesia. Seventeen-day-old CD-1 mice received intra-tympanic gentamicin (IT-Gent) injections to precipitate IED. The movement response to hypercarbia, hypoxia and hypoxia-hypercarbia was compared to controls under light anesthesia. Hypercarbia did not stimulate vigorous movements in any animals under either sleep condition. Hypoxia triggered vigorous movements in controls (p<0.05) and a decreased response in IT-Gent animals under light anesthesia. This contrasted with combined hypoxia-hypercarbia, in which IT-Gent animals displaced significantly suppressed movements compared to controls (p<0.05). Our findings portray that a degree of intact inner ear function is necessary for instigating the movement response. Additionally, hypoxia is the trigger for the movement response while carbon dioxide (CO2) suppresses it. The finding that carbon dioxide did not stimulate movement during natural sleep is an important finding. This contrasts with other studies that have identified hypercarbia as an arousal stimulus with EEG. Further studies are warranted to evaluate the precise role of the inner ear in the movement response and potential association with SIDS. The early detection of IED in SIDS predisposed cases could be invaluable.
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Affiliation(s)
- Sanja Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, 1900 Ninth Avenue, Seattle, WA 98101, United States
| | - Travis Allen
- Department of Anesthesia, Seattle Children's Hospital, 4800 Sandpoint Way NE, Seattle, WA 98105, United States; Center for Integrative Brain Research, Seattle Children's Research Institute, 1900 Ninth Avenue, Seattle, WA 98101, United States; Department of Anesthesia, University of Washington, Seattle, WA, United States
| | - Lindsay Villagracia
- Center for Integrative Brain Research, Seattle Children's Research Institute, 1900 Ninth Avenue, Seattle, WA 98101, United States
| | - Yooree Chae
- Center for Integrative Brain Research, Seattle Children's Research Institute, 1900 Ninth Avenue, Seattle, WA 98101, United States
| | - Jan M Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, 1900 Ninth Avenue, Seattle, WA 98101, United States; Department of Pediatrics, University of Washington, Seattle, WA, United States
| | - Daniel D Rubens
- Department of Anesthesia, Seattle Children's Hospital, 4800 Sandpoint Way NE, Seattle, WA 98105, United States; Center for Integrative Brain Research, Seattle Children's Research Institute, 1900 Ninth Avenue, Seattle, WA 98101, United States; Department of Anesthesia, University of Washington, Seattle, WA, United States.
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Porzionato A, Macchi V, Stecco C, Loukas M, Tubbs RS, De Caro R. Forensic clinical anatomy: A new field of study with application to medicolegal issues. Clin Anat 2016; 30:2-5. [PMID: 27646460 DOI: 10.1002/ca.22796] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Accepted: 09/12/2016] [Indexed: 11/11/2022]
Abstract
Forensic clinical anatomy is a new practical application of the discipline of Clinical Anatomy for ascertaining and evaluating medicolegal questions. In particular, individual anatomy (normal anatomy, anatomical variations, age-, disease-, or surgery-related modifications) can acquire significant relevance in various fields of legal medicine such as child abuse, sudden death, medical responsibility and/or liability, personal injury and damage. Anatomical data of forensic interest frequently arise from the correct application of methods of ascertainment; anatomical methods may then be required for further comprehensive analysis. The rigorous interpretation of anatomical data, derived from the ascertainment phase and analyzed on the basis of pertinent literature, can be pivotal for the correct application of evaluation criteria in various forensic contexts. Clin. Anat. 30:2-5, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
| | | | - Carla Stecco
- Section of Anatomy, University of Padova, Padova, Italy
| | - Marios Loukas
- Department of Anatomical Sciences, St. George's University, True Blue, Grenada, West Indies
| | - R Shane Tubbs
- Department of Anatomical Sciences, St. George's University, True Blue, Grenada, West Indies.,Seattle Science Foundation, Seattle, Washington
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MacFarlane PM, Mayer CA, Litvin DG. Microglia modulate brainstem serotonergic expression following neonatal sustained hypoxia exposure: implications for sudden infant death syndrome. J Physiol 2016; 594:3079-94. [PMID: 26659585 DOI: 10.1113/jp271845] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Accepted: 12/07/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Neonatal sustained hypoxia exposure modifies brainstem microglia and serotonin expression. The altered brainstem neurochemistry is associated with impaired ventilatory responses to acute hypoxia and mortality. The deleterious effects of sustained hypoxia exposure can be prevented by an inhibitor of activated microglia. These observations demonstrate a potential cause of the brainstem serotonin abnormalities thought to be involved in sudden infant death syndrome. ABSTRACT We showed previously that the end of the second postnatal week (days P11-15) represents a period of development during which the respiratory neural control system exhibits a heightened vulnerability to sustained hypoxia (SH, 11% O2 , 5 days) exposure. In the current study, we investigated whether the vulnerability to SH during the same developmental time period is associated with changes in brainstem serotonin (5-HT) expression and whether it can be prevented by the microglia inhibitor minocycline. Using whole-body plethysmography, SH attenuated the acute (5 min) hypoxic ventilatory response (HVR) and caused a high incidence of mortality compared to normoxia rats. SH also increased microglia cell numbers and decreased 5-HT immunoreactivity in the nucleus of the solitary tract (nTS) and dorsal motor nucleus of the vagus (DMNV). The attenuated HVR, mortality, and changes in nTS and DMNV immunoreactivity was prevented by minocycline (25 mg kg(-1) /2 days during SH). These data demonstrate that the 5-HT abnormalities in distinct respiratory neural control regions can be initiated by prolonged hypoxia exposure and may be modulated by microglia activity. These observations share several commonalities with the risk factors thought to underlie the aetiology of sudden infant death syndrome, including: (1) a vulnerable neonate; (2) a critical period of development; (3) evidence of hypoxia; (4) brainstem gliosis (particularly the nTS and DMNV); and (5) 5-HT abnormalities.
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Affiliation(s)
- P M MacFarlane
- Department of Pediatrics, Rainbow Babies & Children's Hospital, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - C A Mayer
- Department of Pediatrics, Rainbow Babies & Children's Hospital, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - D G Litvin
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106, USA
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21
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Oxygen-sensing by arterial chemoreceptors: Mechanisms and medical translation. Mol Aspects Med 2016; 47-48:90-108. [DOI: 10.1016/j.mam.2015.12.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 12/01/2015] [Indexed: 12/30/2022]
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22
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Lonsdale D. Sudden infant death syndrome and abnormal metabolism of thiamin. Med Hypotheses 2015; 85:922-6. [DOI: 10.1016/j.mehy.2015.09.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 09/09/2015] [Indexed: 11/25/2022]
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Abstract
Recent advances have clarified how the brain detects CO2 to regulate breathing (central respiratory chemoreception). These mechanisms are reviewed and their significance is presented in the general context of CO2/pH homeostasis through breathing. At rest, respiratory chemoreflexes initiated at peripheral and central sites mediate rapid stabilization of arterial PCO2 and pH. Specific brainstem neurons (e.g., retrotrapezoid nucleus, RTN; serotonergic) are activated by PCO2 and stimulate breathing. RTN neurons detect CO2 via intrinsic proton receptors (TASK-2, GPR4), synaptic input from peripheral chemoreceptors and signals from astrocytes. Respiratory chemoreflexes are arousal state dependent whereas chemoreceptor stimulation produces arousal. When abnormal, these interactions lead to sleep-disordered breathing. During exercise, central command and reflexes from exercising muscles produce the breathing stimulation required to maintain arterial PCO2 and pH despite elevated metabolic activity. The neural circuits underlying central command and muscle afferent control of breathing remain elusive and represent a fertile area for future investigation.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, VA 22908-0735, USA.
| | - Douglas A Bayliss
- Department of Pharmacology, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, VA 22908-0735, USA
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Macías D, Fernández-Agüera MC, Bonilla-Henao V, López-Barneo J. Deletion of the von Hippel-Lindau gene causes sympathoadrenal cell death and impairs chemoreceptor-mediated adaptation to hypoxia. EMBO Mol Med 2015; 6:1577-92. [PMID: 25385837 PMCID: PMC4287976 DOI: 10.15252/emmm.201404153] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Mutations of the von Hippel–Lindau (VHL) gene are associated with pheochromocytomas and paragangliomas, but the role of VHL in sympathoadrenal homeostasis is unknown. We generated mice lacking Vhl in catecholaminergic cells. They exhibited atrophy of the carotid body (CB), adrenal medulla, and sympathetic ganglia. Vhl-null animals had an increased number of adult CB stem cells, although the survival of newly generated neuron-like glomus cells was severely compromised. The effects of Vhl deficiency were neither prevented by pharmacological inhibition of prolyl hydroxylases or selective genetic down-regulation of prolyl hydroxylase-3, nor phenocopied by hypoxia inducible factor overexpression. Vhl-deficient animals appeared normal in normoxia but survived for only a few days in hypoxia, presenting with pronounced erythrocytosis, pulmonary edema, and right cardiac hypertrophy. Therefore, in the normal sympathoadrenal setting, Vhl deletion does not give rise to tumors but impairs development and plasticity of the peripheral O2-sensing system required for survival in hypoxic conditions.
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Affiliation(s)
- David Macías
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Mary Carmen Fernández-Agüera
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Victoria Bonilla-Henao
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - José López-Barneo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
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Samarasinghe TD, Sands SA, Skuza EM, Joshi MS, Nold-Petry CA, Berger PJ. The effect of prenatal maternal infection on respiratory function in mouse offspring: evidence for enhanced chemosensitivity. J Appl Physiol (1985) 2015; 119:299-307. [PMID: 26023231 DOI: 10.1152/japplphysiol.01105.2014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 05/26/2015] [Indexed: 11/22/2022] Open
Abstract
Systemic maternal inflammation is implicated in preterm birth and bronchopulmonary dysplasia (BPD) and may induce morbidities including reduced pulmonary function, sleep-disordered breathing, and cardiovascular disorders. Here we test the hypothesis that antenatal maternal inflammation per se causes altered alveolar development and increased chemoreflex sensitivity that persists beyond infancy. Pregnant C57BL/6 mice were administered lipopolysaccharide (LPS) (150 μg/kg ip) to induce maternal inflammation or saline (SHAM) at embryonic day 16 (randomized). Pups were weighed daily. On days 7, 28, and 60 (D07, D28, and D60), unrestrained wholebody plethysmography quantified ventilation and chemoreflex responses to hypoxia (10%), hypercapnia (7%), and asphyxia (hypoxic hypercapnia). Lungs were harvested to quantify alveolar number, size, and septal thickness. LPS pups had reduced baseline ventilation per unit bodyweight (∼40%, P < 0.001) vs. SHAM. LPS increased ventilatory responses to hypoxia (D07: 66% vs. 28% increase in ventilation; P < 0.001) hypercapnia (170% vs. 88%; P < 0.001), and asphyxia (249% vs. 154%; P < 0.001); hypersensitive hypoxic responsiveness persisted until D60 (P < 0.001). LPS also increased apnea frequency (P < 0.01). LPS caused thicker alveolar septae (D07, P < 0.001), diminished alveolar number (D28, P < 0.001) vs. SHAM, but effects were minimal by D60. Pups delivered from mothers exposed to antenatal inflammation exhibit deficits in lung structure and hypersensitive responses to respiratory stimuli that persist beyond the newborn period. Antenatal inflammation may contribute to impaired gas exchange and unstable breathing in newborn infants and adversely affect long-term health.
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Affiliation(s)
| | - Scott A Sands
- Division of Sleep Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts; Department of Allergy Immunology and Respiratory Medicine and Central Clinical School, The Alfred and Monash University, Melbourne, Victoria, Australia; and
| | - Elizabeth M Skuza
- Ritchie Centre, MIMR-PHI Institute of Medical Research, Clayton, Victoria, Australia
| | - Mandar S Joshi
- Kentucky Children's Hospital/UK Healthcare, Department of Pediatrics, University of Kentucky College of Medicine, Lexington, Kentucky
| | - Claudia A Nold-Petry
- Ritchie Centre, MIMR-PHI Institute of Medical Research, Clayton, Victoria, Australia
| | - Philip J Berger
- Ritchie Centre, MIMR-PHI Institute of Medical Research, Clayton, Victoria, Australia;
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Porzionato A, Sfriso MM, Mazzatenta A, Macchi V, De Caro R, Di Giulio C. Effects of hyperoxic exposure on signal transduction pathways in the lung. Respir Physiol Neurobiol 2015; 209:106-14. [DOI: 10.1016/j.resp.2014.12.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 11/26/2014] [Accepted: 12/01/2014] [Indexed: 12/18/2022]
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Abstract
Lung ventilation fluctuates widely with behavior but arterial PCO2 remains stable. Under normal conditions, the chemoreflexes contribute to PaCO2 stability by producing small corrective cardiorespiratory adjustments mediated by lower brainstem circuits. Carotid body (CB) information reaches the respiratory pattern generator (RPG) via nucleus solitarius (NTS) glutamatergic neurons which also target rostral ventrolateral medulla (RVLM) presympathetic neurons thereby raising sympathetic nerve activity (SNA). Chemoreceptors also regulate presympathetic neurons and cardiovagal preganglionic neurons indirectly via inputs from the RPG. Secondary effects of chemoreceptors on the autonomic outflows result from changes in lung stretch afferent and baroreceptor activity. Central respiratory chemosensitivity is caused by direct effects of acid on neurons and indirect effects of CO2 via astrocytes. Central respiratory chemoreceptors are not definitively identified but the retrotrapezoid nucleus (RTN) is a particularly strong candidate. The absence of RTN likely causes severe central apneas in congenital central hypoventilation syndrome. Like other stressors, intense chemosensory stimuli produce arousal and activate circuits that are wake- or attention-promoting. Such pathways (e.g., locus coeruleus, raphe, and orexin system) modulate the chemoreflexes in a state-dependent manner and their activation by strong chemosensory stimuli intensifies these reflexes. In essential hypertension, obstructive sleep apnea and congestive heart failure, chronically elevated CB afferent activity contributes to raising SNA but breathing is unchanged or becomes periodic (severe CHF). Extreme CNS hypoxia produces a stereotyped cardiorespiratory response (gasping, increased SNA). The effects of these various pathologies on brainstem cardiorespiratory networks are discussed, special consideration being given to the interactions between central and peripheral chemoreflexes.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia
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28
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Guyenet PG, Abbott SBG. Chemoreception and asphyxia-induced arousal. Respir Physiol Neurobiol 2013; 188:333-43. [PMID: 23608705 PMCID: PMC3749262 DOI: 10.1016/j.resp.2013.04.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/02/2013] [Accepted: 04/06/2013] [Indexed: 02/07/2023]
Abstract
Arousal protects against the adverse and potentially fatal effects of asphyxia during sleep. Asphyxia stimulates the carotid bodies and central chemoreceptors but the sequence of events leading to arousal is uncertain. In this review, the theoretical mechanisms leading to arousal from sleep are briefly summarized and the issue of whether central respiratory chemoreceptors (CRCs) or other types of CO2-responsive CNS neurons contribute to asphyxia-induced arousal is discussed. We focus on the role of the retrotrapezoid nucleus, the raphe and the locus coeruleus and emphasize the anatomical and neurophysiological evidence which suggests that these putative central chemoreceptors could contribute to arousal independently of their effects on breathing. Finally, we describe recent attempts to test the contribution of specific brainstem pathways to asphyxia-induced arousal using optogenetic and other tools and the possible contribution of a group of hypoxia-sensitive brainstem neurons (the C1 cells) to breathing and arousal.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, United States.
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29
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Porzionato A, Macchi V, De Caro R, Di Giulio C. Inflammatory and immunomodulatory mechanisms in the carotid body. Respir Physiol Neurobiol 2013; 187:31-40. [PMID: 23485800 DOI: 10.1016/j.resp.2013.02.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 02/05/2013] [Accepted: 02/19/2013] [Indexed: 10/27/2022]
Abstract
Evidence is available about the role of inflammatory/immunological factors in the physiology and plasticity of the carotid body, with potential clinical implications in obstructive sleep apnea syndrome and sudden infant death syndrome. In humans, lymphomonocytic aggregations (chronic carotid glomitis) have been reported in aging and opiate addiction. Glomus cells produce prostaglandin E2 and the cytokines interleukin 1β, interleukin 6 and TNF-α, with corresponding receptors. These factors modulate glomus cell excitability, catecholamine release and/or chemoreceptor discharge. The above cytokines are up-regulated in chronic sustained or intermittent hypoxia, and prevention of these changes, with ibuprofen or dexamethasone, may modulate hypoxia-induced changes in carotid body chemosensitivity. The main transcription factors considered to be involved are NF-kB and HIFs. Circulating immunogens (lipopolysaccharide) and cytokines may also affect peripheral arterial chemoreception, with the carotid body exerting an immunosensing function.
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Affiliation(s)
- Andrea Porzionato
- Section of Anatomy, Department of Molecular Medicine, University of Padova, Padova, Italy.
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Carroll JL, Donnelly DF, Bairam A. Foreword. Development of the carotid body. Respir Physiol Neurobiol 2013; 185:1-2. [PMID: 23078973 DOI: 10.1016/j.resp.2012.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 10/09/2012] [Indexed: 11/29/2022]
Affiliation(s)
- John L Carroll
- Division of Pediatric Pulmonary Medicine, Department of Pediatrics, University of Arkansas for Medical Sciences, Arkansas Children's Hospital, 1 Children's Way, Little Rock, AR 72202, USA.
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