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Barrett KT, Hasan SU, Scantlebury MH, Wilson RJA. Impaired cardiorespiratory responses to hypercapnia in neonatal mice lacking PAC1 but not VPAC2 receptors. Am J Physiol Regul Integr Comp Physiol 2021; 320:R116-R128. [PMID: 33146556 DOI: 10.1152/ajpregu.00161.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The evidence is mounting for a role for abnormal signaling of the stress peptide pituitary adenylate cyclase activating polypeptide (PACAP) and its canonical receptor PAC1 in the pathogenesis of sudden infant death syndrome. In this study, we investigated whether the PACAP receptors PAC1 or VPAC2 are involved in the neonatal cardiorespiratory response to hypercapnic stress. We used head-out plethysmography and surface ECG electrodes to assess cardiorespiratory responses to an 8% hypercapnic challenge in unanesthetized and spontaneously breathing 4-day-old PAC1 or VPAC2 knockout (KO) and wild-type mouse pups. We demonstrate that compared with WTs, breathing frequency (RR) and minute ventilation ([Formula: see text]) in PAC1 KO pups were significantly blunted in response to hypercapnia. Although heart rate was unaltered in PAC1 KO pups during hypercapnia, heart rate recovery posthypercapnia was impaired. In contrast, cardiorespiratory impairments in VPAC2 KO pups were limited to only an overall higher tidal volume (VT), independent of treatment. These findings suggest that PACAP signaling through the PAC1 receptor plays a more important role than signaling through the VPAC2 receptor in neonatal respiratory responses to hypercapnia. Thus deficits in PACAP signaling primarily via PAC1 may contribute to the inability of infants to mount an appropriate protective response to homeostatic stressors in childhood disorders such as 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, Alberta, Canada
| | - Shabih U Hasan
- Department of Pediatrics, Alberta Children's Hospital Research Institute, University of Calgary, Alberta, Canada
| | - Morris H Scantlebury
- Department of Pediatrics, Clinical Neuroscience, Alberta Children's Hospital Research Institute, University of 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, Alberta, Canada
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2
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Di Lascio S, Benfante R, Cardani S, Fornasari D. Advances in the molecular biology and pathogenesis of congenital central hypoventilation syndrome—implications for new therapeutic targets. Expert Opin Orphan Drugs 2018. [DOI: 10.1080/21678707.2018.1540978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Simona Di Lascio
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, Milan, Italy
| | - Roberta Benfante
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, Milan, Italy
- CNR- Neuroscience Institute, Milan, Italy
| | - Silvia Cardani
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, Milan, Italy
| | - Diego Fornasari
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, Milan, Italy
- CNR- Neuroscience Institute, Milan, Italy
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3
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Cerpa VJ, Wu Y, Bravo E, Teran FA, Flynn RS, Richerson GB. Medullary 5-HT neurons: Switch from tonic respiratory drive to chemoreception during postnatal development. Neuroscience 2016; 344:1-14. [PMID: 27619736 DOI: 10.1016/j.neuroscience.2016.09.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 08/30/2016] [Accepted: 09/01/2016] [Indexed: 01/27/2023]
Abstract
Serotonin (5-HT) neurons contribute to respiratory chemoreception in adult mice, but it is unclear whether they play a similar role in neonatal mice. We studied breathing during development in Lmx1bf/f/p mice, which lack 5-HT neurons. From postnatal days 1-7 (P1-P7), ventilation of Lmx1bf/f/p mice breathing room air was 50% of WT mice (p<0.001). By P12, baseline ventilation increased to a level equal to WT mice. In contrast, the hypercapnic ventilatory response (HCVR) of neonatal Lmx1bf/f/p and WT mice was equal to each other, but were both much less than adult WT mice. By P21 the HCVR of WT mice increased to near adult levels, but the HCVR of Lmx1bf/f/p mice had not changed, and was 42% less than WT mice. Primary cell cultures were prepared from the ventromedial medulla of neonatal mice, and patch-clamp recordings were made from neurons identified as serotonergic by expression of a reporter gene. In parallel with developmental changes of the HCVR in vivo, 5-HT neurons had little chemosensitivity to acidosis until 12days in vitro (DIV), after which their response increased to reach a plateau around 25 DIV. Neonatal Lmx1bf/f/p mice displayed high mortality and decreased growth rate, and this worsened in hypoxia. Mortality was decreased in hyperoxia. These results indicate that maturation of 5-HT neurons contributes to development of respiratory CO2/pH chemoreception during the first few weeks of life in mice in vivo. A defect in the 5-HT system in early postnatal life decreases survival due in part to hypoxia.
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Affiliation(s)
- Veronica J Cerpa
- Department of Neurology, Yale University, New Haven, CT 06510, United States; Department of Neurology, University of Iowa, Iowa City, IA 52242, United States
| | - Yuanming Wu
- Department of Neurology, Yale University, New Haven, CT 06510, United States; Department of Neurology, University of Iowa, Iowa City, IA 52242, United States
| | - Eduardo Bravo
- Department of Neurology, University of Iowa, Iowa City, IA 52242, United States.
| | - Frida A Teran
- Department of Neurology, University of Iowa, Iowa City, IA 52242, United States
| | - Rachel S Flynn
- Department of Neurology, Yale University, New Haven, CT 06510, United States
| | - George B Richerson
- Department of Neurology, Yale University, New Haven, CT 06510, United States; Department of Neurology, University of Iowa, Iowa City, IA 52242, United States; Department of Molecular Physiology & Biophysics, University of Iowa, Iowa City, IA 52242, United States; Veterans Affairs Medical Center, Iowa City, IA 52242, United States
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4
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Bourgeois T, Delezoide AL, Zhao W, Guimiot F, Adle-Biassette H, Durand E, Ringot M, Gallego J, Storme T, Le Guellec C, Kassaï B, Turner MA, Jacqz-Aigrain E, Matrot B. Safety study of Ciprofloxacin in newborn mice. Regul Toxicol Pharmacol 2016; 74:161-9. [DOI: 10.1016/j.yrtph.2015.11.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 11/05/2015] [Indexed: 01/08/2023]
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5
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Bollen B, Ramanantsoa N, Naert A, Matrot B, Van den Bergh O, D'Hooge R, Gallego J. Emotional disorders in adult mice heterozygous for the transcription factor Phox2b. Physiol Behav 2015; 141:120-6. [PMID: 25582512 DOI: 10.1016/j.physbeh.2015.01.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Revised: 01/06/2015] [Accepted: 01/08/2015] [Indexed: 12/16/2022]
Abstract
Phox2b is an essential transcription factor for the development of the autonomic nervous system. Mice carrying one invalidated Phox2b allele (Phox2b(+/-)) show mild autonomic disorders including sleep apneas, and impairments in chemosensitivity and thermoregulation that recover within 10days of postnatal age. Because Phox2b is not expressed above the pons nor in the cerebellum, this mutation is not expected to affect brain development and cognitive functioning directly. However, the transient physiological disorders in Phox2b(+/-) mice might impair neurodevelopment. To examine this possibility, we conducted a behavioral test battery of emotional, motor, and cognitive functioning in adult Phox2b(+/-) mice and their wildtype littermates (Phox2b(+/+)). Adult Phox2b(+/-) mice showed altered exploratory behavior in the open field and in the elevated plus maze, both indicative of anxiety. Phox2b(+/-) mice did not show cognitive or motor impairments. These results suggest that also mild autonomic control deficits may disturb long-term emotional development.
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Affiliation(s)
- Bieke Bollen
- Laboratory of Biological Psychology, University of Leuven, Belgium; INSERM, U1141, Hôpital Robert Debré, 75019 Paris, France
| | - Nelina Ramanantsoa
- INSERM, U1141, Hôpital Robert Debré, 75019 Paris, France; Université Paris Diderot, Sorbonne Paris Cité, 75019 Paris, France
| | - Arne Naert
- Laboratory of Biological Psychology, University of Leuven, Belgium
| | - Boris Matrot
- INSERM, U1141, Hôpital Robert Debré, 75019 Paris, France; Université Paris Diderot, Sorbonne Paris Cité, 75019 Paris, France
| | | | - Rudi D'Hooge
- Laboratory of Biological Psychology, University of Leuven, Belgium
| | - Jorge Gallego
- INSERM, U1141, Hôpital Robert Debré, 75019 Paris, France; Université Paris Diderot, Sorbonne Paris Cité, 75019 Paris, France.
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6
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Gallego J. Genetic diseases: congenital central hypoventilation, Rett, and Prader-Willi syndromes. Compr Physiol 2013; 2:2255-79. [PMID: 23723037 DOI: 10.1002/cphy.c100037] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The present review summarizes current knowledge on three rare genetic disorders of respiratory control, congenital central hypoventilation syndrome (CCHS), Rett syndrome (RTT), and Prader-Willi syndrome (PWS). CCHS is characterized by lack of ventilatory chemosensitivity caused by PHOX2B gene abnormalities consisting mainly of alanine expansions. RTT is associated with episodes of tachypneic and irregular breathing intermixed with breathholds and apneas and is caused by mutations in the X-linked MECP2 gene encoding methyl-CpG-binding protein. PWS manifests as sleep-disordered breathing with apneas and episodes of hypoventilation and is caused by the loss of a group of paternally inherited genes on chromosome 15. CCHS is the most specific disorder of respiratory control, whereas the breathing disorders in RTT and PWS are components of a more general developmental disorder. The main clinical features of these three disorders are reviewed with special emphasis on the associated brain abnormalities. In all three syndromes, disease-causing genetic defects have been identified, allowing the development of genetically engineered mouse models. New directions for future therapies based on these models or, in some cases, on clinical experience are delineated. Studies of CCHS, RTT, and PWS extend our knowledge of the molecular and cellular aspects of respiratory rhythm generation and suggest possible pharmacological approaches to respiratory control disorders. This knowledge is relevant for the clinical management of many respiratory disorders that are far more prevalent than the rare diseases discussed here.
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Affiliation(s)
- Jorge Gallego
- Inserm U676 and University of Paris Diderot, Paris, France.
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7
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Ramanantsoa N, Gallego J. Congenital central hypoventilation syndrome. Respir Physiol Neurobiol 2013; 189:272-9. [PMID: 23692929 DOI: 10.1016/j.resp.2013.05.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 05/03/2013] [Accepted: 05/14/2013] [Indexed: 10/26/2022]
Abstract
Congenital central hypoventilation syndrome (CCHS) is characterized by hypoventilation during sleep and impaired ventilatory responses to hypercapnia and hypoxemia. Most cases are sporadic and caused by de novo PHOX2B gene mutations, which are usually polyalanine repeat expansions. Physiological and neuroanatomical studies of genetically engineered mice and analyses of cellular responses to mutated Phox2b have shed light on the pathophysiological mechanisms of CCHS. Findings in Phox2b(27Ala/+) knock-in mice consisted of unstable breathing with apneas, absence of the ventilatory response to hypercapnia, death within a few hours after birth, and absence of the retrotrapezoid nucleus (RTN). Conditional mouse mutants in which Phox2b(27Ala) was targeted to the RTN also lacked the ventilatory response to hypercapnia at birth but survived to adulthood and developed a partial hypercapnia response. The therapeutic effects of desogestrel are being evaluated in clinical trials, and recent analyses of cellular responses to polyAla Phox2b aggregates have suggested new pharmacological approaches designed to counteract the toxic effects of mutated Phox2b.
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Affiliation(s)
- N Ramanantsoa
- INSERM, U676, Hôpital Robert Debré, 75019 Paris, France; Université Paris Diderot, Paris, France
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8
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Zehendner CM, Luhmann HJ, Yang JW. A simple and novel method to monitor breathing and heart rate in awake and urethane-anesthetized newborn rodents. PLoS One 2013; 8:e62628. [PMID: 23658756 PMCID: PMC3643944 DOI: 10.1371/journal.pone.0062628] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 03/22/2013] [Indexed: 11/18/2022] Open
Abstract
Rodents are most useful models to study physiological and pathophysiological processes in early development, because they are born in a relatively immature state. However, only few techniques are available to monitor non-invasively heart frequency and respiratory rate in neonatal rodents without restraining or hindering access to the animal. Here we describe experimental procedures that allow monitoring of heart frequency by electrocardiography (ECG) and breathing rate with a piezoelectric transducer (PZT) element without hindering access to the animal. These techniques can be easily installed and are used in the present study in unrestrained awake and anesthetized neonatal C57/Bl6 mice and Wistar rats between postnatal day 0 and 7. In line with previous reports from awake rodents we demonstrate that heart rate in rats and mice increases during the first postnatal week. Respiratory frequency did not differ between both species, but heart rate was significantly higher in mice than in rats. Further our data indicate that urethane, an agent that is widely used for anesthesia, induces a hypoventilation in neonates whilst heart rate remains unaffected at a dose of 1 g per kg body weight. Of note, hypoventilation induced by urethane was not detected in rats at postnatal 0/1. To verify the detected hypoventilation we performed blood gas analyses. We detected a respiratory acidosis reflected by a lower pH and elevated level in CO2 tension (pCO2) in both species upon urethane treatment. Furthermore we found that metabolism of urethane is different in P0/1 mice and rats and between P0/1 and P6/7 in both species. Our findings underline the usefulness of monitoring basic cardio-respiratory parameters in neonates during anesthesia. In addition our study gives information on developmental changes in heart and breathing frequency in newborn mice and rats and the effects of urethane in both species during the first postnatal week.
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Affiliation(s)
- Christoph M. Zehendner
- Institute of Physiology and Pathophysiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Heiko J. Luhmann
- Institute of Physiology and Pathophysiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Jenq-Wei Yang
- Institute of Physiology and Pathophysiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
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10
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Ramanantsoa N, Matrot B, Vardon G, Lajard AM, Voituron N, Dauger S, Denjean A, Hilaire G, Gallego J. Impaired ventilatory and thermoregulatory responses to hypoxic stress in newborn phox2b heterozygous knock-out mice. Front Physiol 2011; 2:61. [PMID: 21977017 PMCID: PMC3178811 DOI: 10.3389/fphys.2011.00061] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 08/30/2011] [Indexed: 11/17/2022] Open
Abstract
The Phox2b genesis necessary for the development of the autonomic nervous system, and especially, of respiratory neuronal circuits. In the present study, we examined the role of Phox2b in ventilatory and thermoregulatory responses to hypoxic stress, which are closely related in the postnatal period. Hypoxic stress was generated by strong thermal stimulus, combined or not with reduced inspired O(2). To this end, we exposed 6-day-old Phox2b(+/-) pups and their wild-type littermates (Phox2b(+/+)) to hypoxia (10% O(2)) or hypercapnia (8% CO(2)) under thermoneutral (33°C) or cold (26°C) conditions. We found that Phox2b(+/-) pups showed less normoxic ventilation (V(E)) in the cold than Phox2b(+/+) pups. Phox2b(+/-) pups also showed lower oxygen consumption (VO(2)) in the cold, reflecting reduced thermogenesis and a lower body temperature. Furthermore, while the cold depressed ventilatory responses to hypoxia and hypercapnia in both genotype groups, this effect was less pronounced in Phox2b(+/-) pups. Finally, because serotonin (5-HT) neurons are pivotal to respiratory and thermoregulatory circuits and depend on Phox2b for their differentiation, we studied 5-HT metabolism using high pressure liquid chromatography, and found that it was altered in Phox2b(+/-) pups. We conclude that Phox2b haploinsufficiency alters the ability of newborns to cope with metabolic challenges, possibly due to 5-HT signaling impairments.
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Affiliation(s)
- Nelina Ramanantsoa
- INSERM, UMR 676, Robert Debré HospitalParis, France
- Faculty of Medicine, University Denis DiderotParis, France
| | - Boris Matrot
- INSERM, UMR 676, Robert Debré HospitalParis, France
- Faculty of Medicine, University Denis DiderotParis, France
| | - Guy Vardon
- Faculty of Medicine, University of AmiensAmiens, France
| | - Anne-Marie Lajard
- CNRS, UMR 6231, Faculty Saint Jérôme, Research Center of Neurobiology and Neurophysiology of Marseille, University of Aix-Marseille II and IIIMarseille, France
| | - Nicolas Voituron
- CNRS, UMR 6231, Faculty Saint Jérôme, Research Center of Neurobiology and Neurophysiology of Marseille, University of Aix-Marseille II and IIIMarseille, France
| | - Stéphane Dauger
- INSERM, UMR 676, Robert Debré HospitalParis, France
- Faculty of Medicine, University Denis DiderotParis, France
- Pediatric Intensive Care Unit, AP–HP, Robert Debré HospitalParis, France
| | - André Denjean
- INSERM, UMR 676, Robert Debré HospitalParis, France
- Faculty of Medicine, University Denis DiderotParis, France
- Physiology Department, AP–HP, Robert Debré HospitalParis, France
| | - Gérard Hilaire
- CNRS, UMR 6231, Faculty Saint Jérôme, Research Center of Neurobiology and Neurophysiology of Marseille, University of Aix-Marseille II and IIIMarseille, France
| | - Jorge Gallego
- INSERM, UMR 676, Robert Debré HospitalParis, France
- Faculty of Medicine, University Denis DiderotParis, France
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11
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Favrais G, van de Looij Y, Fleiss B, Ramanantsoa N, Bonnin P, Stoltenburg-Didinger G, Lacaud A, Saliba E, Dammann O, Gallego J, Sizonenko S, Hagberg H, Lelièvre V, Gressens P. Systemic inflammation disrupts the developmental program of white matter. Ann Neurol 2011; 70:550-65. [PMID: 21796662 DOI: 10.1002/ana.22489] [Citation(s) in RCA: 296] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 05/11/2011] [Accepted: 05/13/2011] [Indexed: 12/23/2022]
Abstract
OBJECTIVE Perinatal inflammation is a major risk factor for neurological deficits in preterm infants. Several experimental studies have shown that systemic inflammation can alter the programming of the developing brain. However, these studies do not offer detailed pathophysiological mechanisms, and they rely on relatively severe infectious or inflammatory stimuli that most likely do not reflect the levels of systemic inflammation observed in many human preterm infants. The goal of the present study was to test the hypothesis that moderate systemic inflammation is sufficient to alter white matter development. METHODS Newborn mice received twice-daily intraperitoneal injections of interleukin-1β (IL-1β) over 5 days and were studied for myelination, oligodendrogenesis, and behavior and with magnetic resonance imaging (MRI). RESULTS Mice exposed to IL-1β had a long-lasting myelination defect that was characterized by an increased number of nonmyelinated axons. They also displayed a reduction of the diameter of the myelinated axons. In addition, IL-1β induced a significant reduction of the density of myelinating oligodendrocytes accompanied by an increased density of oligodendrocyte progenitors, suggesting a partial blockade in the oligodendrocyte maturation process. Accordingly, IL-1β disrupted the coordinated expression of several transcription factors known to control oligodendrocyte maturation. These cellular and molecular abnormalities were correlated with a reduced white matter fractional anisotropy on diffusion tensor imaging and with memory deficits. INTERPRETATION Moderate perinatal systemic inflammation alters the developmental program of the white matter. This insult induces a long-lasting myelination deficit accompanied by cognitive defects and MRI abnormalities, further supporting the clinical relevance of the present data.
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Affiliation(s)
- Géraldine Favrais
- INSERM U676, Denis Diderot Faculty of Medicine, University of Paris 7, Paris, France
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12
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Arousal response to hypoxia in newborns: Insights from animal models. Biol Psychol 2010; 84:39-45. [DOI: 10.1016/j.biopsycho.2009.12.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 11/30/2009] [Accepted: 12/02/2009] [Indexed: 11/24/2022]
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13
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Amiel J, Dubreuil V, Ramanantsoa N, Fortin G, Gallego J, Brunet JF, Goridis C. PHOX2B in respiratory control: Lessons from congenital central hypoventilation syndrome and its mouse models. Respir Physiol Neurobiol 2009; 168:125-32. [DOI: 10.1016/j.resp.2009.03.005] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 03/03/2009] [Accepted: 03/04/2009] [Indexed: 11/24/2022]
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14
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Gallego J, Dauger S. PHOX2B mutations and ventilatory control. Respir Physiol Neurobiol 2009; 164:49-54. [PMID: 18675942 DOI: 10.1016/j.resp.2008.07.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Revised: 07/07/2008] [Accepted: 07/09/2008] [Indexed: 01/08/2023]
Abstract
The transcription factor PHOX2B is essential for the development of the autonomic nervous system. In humans, polyalanine expansion mutations in PHOX2B cause Congenital Central Hypoventilation Syndrome (CCHS), a rare life-threatening disorder characterized by hypoventilation during sleep and impaired chemosensitivity. CCHS is combined with comparatively less severe impairments of autonomic functions including thermoregulation, cardiac rhythm, and digestive motility. Respiratory phenotype analyses of mice carrying an invalidated Phox2b allele (Phox2b+/- mutant mice) or the Phox2b mutation (+7 alanine expansion) found in patients with CCHS (Phox2b(27Ala/+) mice) have shed light on the role for PHOX2B in breathing control and on the pathophysiological mechanisms underlying CCHS. Newborn mice that lacked one Phox2b allele (Phox2b+/-) had sleep apneas and depressed sensitivity to hypercapnia. However, these impairments resolved rapidly, whereas the CCHS phenotype is irreversible. Heterozygous Phox2b(27Ala/+) pups exhibited a lack of responsiveness to hypercapnia and unstable breathing; they died within the first few postnatal hours. The generation of mouse models of CCHS provides tools for evaluating treatments aimed at alleviating both the respiratory symptoms and all other autonomic symptoms of CCHS.
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Affiliation(s)
- Jorge Gallego
- INSERM, U676, Hôpital Robert Debré, 48 Bd Sérurier, 75019 Paris, France.
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15
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Dauger S, Ramanantsoa N. [Abnormal control of breathing in pediatrics]. Arch Pediatr 2008; 15:617-9. [PMID: 18582691 DOI: 10.1016/s0929-693x(08)71852-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- S Dauger
- Service de Réanimation et Surveillance Continue Pédiatriques, Pôle de Pédiatrie Aiguë et Médecine Interne, Hôpital Robert-Debré, Assistance Publique-Hôpitaux de Paris, France.
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16
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Gaultier C, Gallego J. Neural control of breathing: insights from genetic mouse models. J Appl Physiol (1985) 2008; 104:1522-30. [DOI: 10.1152/japplphysiol.01266.2007] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Recent studies described the in vivo ventilatory phenotype of mutant newborn mice with targeted deletions of genes involved in the organization and development of the respiratory-neuron network. Whole body flow barometric plethysmography is the noninvasive method of choice for studying unrestrained newborn mice. Breathing-pattern abnormalities with apneas occur in mutant newborn mice that lack genes involved in the development and modulation of rhythmogenesis. Studies of deficits in ventilatory responses to hypercapnia and/or hypoxia helped to identify genes involved in chemosensitivity to oxygen and carbon dioxide. Combined studies in mutant newborn mice and in humans have shed light on the pathogenesis of genetically determined respiratory-control abnormalities such as congenital central hypoventilation syndrome, Rett syndrome, and Prader-Willi syndrome. The development of mouse models has opened up the field of research into new treatments for respiratory-control disorders in humans.
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