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Biniwale M, Ramanathan R, Minoo P. Should nasal respiratory support in preterm infants be tailored for physiologic maturity? Pediatr Res 2024; 95:1402-1403. [PMID: 38228743 PMCID: PMC11126376 DOI: 10.1038/s41390-023-03016-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Accepted: 12/15/2023] [Indexed: 01/18/2024]
Affiliation(s)
- Manoj Biniwale
- Division of Neonatology, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Rangasamy Ramanathan
- Division of Neonatology, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Parviz Minoo
- Division of Neonatology, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
- Hastings Center for Pulmonary Research, Los Angeles, CA, 90033, USA.
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2
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Elsedawi BF, Samson N, Nadeau C, Charette A, Lehoux A, Fortin-Pellerin É, Praud JP. Effects of Nasal Respiratory Support on Laryngeal and Esophageal Reflexes in Preterm Lambs. Pediatr Res 2024; 95:1493-1502. [PMID: 37938316 DOI: 10.1038/s41390-023-02883-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 09/27/2023] [Accepted: 10/18/2023] [Indexed: 11/09/2023]
Abstract
BACKGROUND Significant cardiorespiratory events can be triggered in preterm infants as part of laryngeal chemoreflexes (LCRs) and esophageal reflexes (ERs). We previously showed that nasal continuous positive airway pressure (nCPAP) blunted the cardiorespiratory inhibition induced with LCRs. Therefore, we aimed to compare the effects of nCPAP and high-flow nasal cannulas (HFNC) on the cardiorespiratory events induced during LCRs and ERs. The hypothesis is that nCPAP but not HFNC decreases the cardiorespiratory inhibition observed during LCRs and ERs. METHODS Eleven preterm lambs were instrumented to record respiration, ECG, oxygenation, and states of alertness. LCRs and ERs were induced during non-rapid eye movement sleep in a random order under these conditions: nCPAP 6 cmH2O, HFNC 7 L/min, high-flow nasal cannulas 7 L/min at a tracheal pressure of 6 cmH2O, and no respiratory support. RESULTS nCPAP 6 cmH2O decreased the cardiorespiratory inhibition induced with LCRs, but not with ERs in preterm lambs. This blunting effect was less marked with HFNC 7 L/min, even when the tracheal pressure was maintained at 6 cmH2O. CONCLUSIONS nCPAP might be a treatment for cardiorespiratory events related to LCRs in newborns, either in the context of laryngopharyngeal refluxes or swallowing immaturity. Our preclinical results merit to be confirmed through clinical studies. IMPACT Laryngeal chemoreflexes can be responsible for significant cardiorespiratory inhibition in newborns, especially preterm. Nasal continuous positive airway pressure at 6 cmH2O significantly decreased this cardiorespiratory inhibition. High-flow nasal cannulas at 7 L/min had a lesser effect than nasal continuous positive airway pressure. Esophageal stimulation was responsible for a smaller cardiorespiratory inhibition, which was not significantly modified by nasal continuous positive airway pressure or high-flow nasal cannulas. Nasal continuous positive airway pressure should be tested for its beneficial effect on cardiorespiratory events related to laryngeal chemoreflexes in preterm newborns.
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Affiliation(s)
- Basma F Elsedawi
- Neonatal Respiratory Research Unit, Departments of Pediatrics and Pharmacology-Physiology, University of Sherbrooke, Sherbrooke, QC, J1H 5N4, Canada
- Department of Human Anatomy and Embryology, Faculty of Medicine, Zagazig University, Zagazig, Sharkia, Arab Republic of Egypt
| | - Nathalie Samson
- Neonatal Respiratory Research Unit, Departments of Pediatrics and Pharmacology-Physiology, University of Sherbrooke, Sherbrooke, QC, J1H 5N4, Canada
| | - Charlène Nadeau
- Neonatal Respiratory Research Unit, Departments of Pediatrics and Pharmacology-Physiology, University of Sherbrooke, Sherbrooke, QC, J1H 5N4, Canada
| | - Arianne Charette
- Neonatal Respiratory Research Unit, Departments of Pediatrics and Pharmacology-Physiology, University of Sherbrooke, Sherbrooke, QC, J1H 5N4, Canada
| | - Angélique Lehoux
- Neonatal Respiratory Research Unit, Departments of Pediatrics and Pharmacology-Physiology, University of Sherbrooke, Sherbrooke, QC, J1H 5N4, Canada
| | - Étienne Fortin-Pellerin
- Neonatal Respiratory Research Unit, Departments of Pediatrics and Pharmacology-Physiology, University of Sherbrooke, Sherbrooke, QC, J1H 5N4, Canada
| | - Jean-Paul Praud
- Neonatal Respiratory Research Unit, Departments of Pediatrics and Pharmacology-Physiology, University of Sherbrooke, Sherbrooke, QC, J1H 5N4, Canada.
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3
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Elliot-Portal E, Arias-Reyes C, Laouafa S, Tam R, Kinkead R, Soliz J. Cerebral Erythropoietin Prevents Sex-Dependent Disruption of Respiratory Control Induced by Early Life Stress. Front Physiol 2021; 12:701344. [PMID: 34987412 PMCID: PMC8720854 DOI: 10.3389/fphys.2021.701344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 11/22/2021] [Indexed: 11/29/2022] Open
Abstract
Injuries that occur early in life are often at the root of adult illness. Neonatal maternal separation (NMS) is a form of early life stress that has persistent and sex-specific effects on the development of neural networks, including those that regulate breathing. The release of stress hormones during a critical period of development contributes to the deleterious consequences of NMS, but the role of increased corticosterone (CORT) in NMS-induced respiratory disturbance is unknown. Because erythropoietin (EPO) is a potent neuroprotectant that prevents conditions associated with hyperactivation of the stress neuroaxis in a sex-specific manner, we hypothesized that EPO reduces the sex-specific alteration of respiratory regulation induced by NMS in adult mice. Animals were either raised under standard conditions (controls) or exposed to NMS 3 h/day from postnatal days 3–12. We tested the efficacy of EPO in preventing the effects of NMS by comparing wild-type mice with transgenic mice that overexpress EPO only in the brain (Tg21). In 7-days-old pups, NMS augmented CORT levels ~2.5-fold by comparison with controls but only in males; this response was reduced in Tg21 mice. Respiratory function was assessed using whole-body plethysmography. Apneas were detected during sleep; the responsiveness to stimuli was measured by exposing mice to hypoxia (10% O2; 15 min) and hypercapnia (5% CO2; 10 min). In wild-type, NMS increased the number of apneas and the hypercapnic ventilatory response (HcVR) only in males; with no effect on Tg21. In wild-type males, the incidence of apneas was positively correlated with HcVR and inversely related to the tachypneic response to hypoxia. We conclude that neural EPO reduces early life stress-induced respiratory disturbances observed in males.
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Affiliation(s)
- Elizabeth Elliot-Portal
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec City, QC, Canada
| | - Christian Arias-Reyes
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec City, QC, Canada
| | - Sofien Laouafa
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec City, QC, Canada
| | - Rose Tam
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec City, QC, Canada
| | - Richard Kinkead
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec City, QC, Canada
| | - Jorge Soliz
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec City, QC, Canada
- High Altitude Pulmonary and Pathology Institute (HAPPI–IPPA), La Paz, Bolivia
- *Correspondence: Jorge Soliz,
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4
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Tenorio-Lopes L, Kinkead R. Sex-Specific Effects of Stress on Respiratory Control: Plasticity, Adaptation, and Dysfunction. Compr Physiol 2021; 11:2097-2134. [PMID: 34107062 DOI: 10.1002/cphy.c200022] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
As our understanding of respiratory control evolves, we appreciate how the basic neurobiological principles of plasticity discovered in other systems shape the development and function of the respiratory control system. While breathing is a robust homeostatic function, there is growing evidence that stress disrupts respiratory control in ways that predispose to disease. Neonatal stress (in the form of maternal separation) affects "classical" respiratory control structures such as the peripheral O2 sensors (carotid bodies) and the medulla (e.g., nucleus of the solitary tract). Furthermore, early life stress disrupts the paraventricular nucleus of the hypothalamus (PVH), a structure that has emerged as a primary determinant of the intensity of the ventilatory response to hypoxia. Although underestimated, the PVH's influence on respiratory function is a logical extension of the hypothalamic control of metabolic demand and supply. In this article, we review the functional and anatomical links between the stress neuroendocrine axis and the medullary network regulating breathing. We then present the persistent and sex-specific effects of neonatal stress on respiratory control in adult rats. The similarities between the respiratory phenotype of stressed rats and clinical manifestations of respiratory control disorders such as sleep-disordered breathing and panic attacks are remarkable. These observations are in line with the scientific consensus that the origins of adult disease are often found among developmental and biological disruptions occurring during early life. These observations bring a different perspective on the structural hierarchy of respiratory homeostasis and point to new directions in our understanding of the etiology of respiratory control disorders. © 2021 American Physiological Society. Compr Physiol 11:1-38, 2021.
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Affiliation(s)
- Luana Tenorio-Lopes
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta, Canada
| | - Richard Kinkead
- Département de Pédiatrie, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada
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5
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Tenorio-Lopes L, Fournier S, Henry MS, Bretzner F, Kinkead R. Disruption of estradiol regulation of orexin neurons: a novel mechanism in excessive ventilatory response to CO 2 inhalation in a female rat model of panic disorder. Transl Psychiatry 2020; 10:394. [PMID: 33173029 PMCID: PMC7656265 DOI: 10.1038/s41398-020-01076-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/01/2020] [Accepted: 10/20/2020] [Indexed: 12/27/2022] Open
Abstract
Panic disorder (PD) is ~2 times more frequent in women. An excessive ventilatory response to CO2 inhalation is more likely during the premenstrual phase. While ovarian hormones appear important in the pathophysiology of PD, their role remains poorly understood as female animals are rarely used in pre-clinical studies. Using neonatal maternal separation (NMS) to induce a "PD-like" respiratory phenotype, we tested the hypothesis that NMS disrupts hormonal regulation of the ventilatory response to CO2 in female rats. We then determined whether NMS attenuates the inhibitory actions of 17-β estradiol (E2) on orexin neurons (ORX). Pups were exposed to NMS (3 h/day; postnatal day 3-12). The ventilatory response to CO2-inhalation was tested before puberty, across the estrus cycle, and following ovariectomy. Plasma E2 and hypothalamic ORXA were measured. The effect of an ORX1 antagonist (SB334867; 15 mg/kg) on the CO2 response was tested. Excitatory postsynaptic currents (EPSCs) were recorded from ORX neurons using whole-cell patch-clamp. NMS-related increase in the CO2 response was observed only when ovaries were functional; the largest ventilation was observed during proestrus. SB334867 blocked this effect. NMS augmented levels of ORXA in hypothalamus extracts. EPSC frequency varied according to basal plasma E2 levels across the estrus cycle in controls but not NMS. NMS reproduces developmental and cyclic changes of respiratory manifestations of PD. NMS disrupts the inhibitory actions of E2 on the respiratory network. Impaired E2-related inhibition of ORX neurons during proestrus is a novel mechanism in respiratory manifestations of PD in females.
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Affiliation(s)
- Luana Tenorio-Lopes
- Hotchkiss Brain Institute; Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Stéphanie Fournier
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec. Département de Pédiatrie. Université Laval, Québec, QC, Canada
| | - Mathilde S Henry
- INRAE, Université de Bordeaux, Bordeaux INP, Nutrineuro, UMR 1286, F-33000, Bordeaux, France
| | - Frédéric Bretzner
- Centre de Recherche du CHU de Québec-Université Laval, Axe Neurosciences. Département de Psychiatrie et de Neurosciences, Université Laval, Québec, QC, Canada
| | - Richard Kinkead
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec. Département de Pédiatrie. Université Laval, Québec, QC, Canada.
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6
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Kuypers K, Martherus T, Lamberska T, Dekker J, Hooper SB, Te Pas AB. Reflexes that impact spontaneous breathing of preterm infants at birth: a narrative review. Arch Dis Child Fetal Neonatal Ed 2020; 105:675-679. [PMID: 32350064 DOI: 10.1136/archdischild-2020-318915] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 03/17/2020] [Accepted: 03/30/2020] [Indexed: 02/06/2023]
Abstract
Some neural circuits within infants are not fully developed at birth, especially in preterm infants. Therefore, it is unclear whether reflexes that affect breathing may or may not be activated during the neonatal stabilisation at birth. Both sensory reflexes (eg, tactile stimulation) and non-invasive ventilation (NIV) can promote spontaneous breathing at birth, but the application of NIV can also compromise breathing by inducing facial reflexes that inhibit spontaneous breathing. Applying an interface could provoke the trigeminocardiac reflex (TCR) by stimulating the trigeminal nerve resulting in apnoea and a reduction in heart rate. Similarly, airflow within the nasopharynx can elicit the TCR and/or laryngeal chemoreflex (LCR), resulting in glottal closure and ineffective ventilation, whereas providing pressure via inflations could stimulate multiple receptors that affect breathing. Stimulating the fast adapting pulmonary receptors may activate Head's paradoxical reflex to stimulate spontaneous breathing. In contrast, stimulating the slow adapting pulmonary receptors or laryngeal receptors could induce the Hering-Breuer inflation reflex or LCR, respectively, and thereby inhibit spontaneous breathing. As clinicians are most often unaware that starting primary care might affect the breathing they intend to support, this narrative review summarises the currently available evidence on (vagally mediated) reflexes that might promote or inhibit spontaneous breathing at birth.
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Affiliation(s)
- Kristel Kuypers
- Neonatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Tessa Martherus
- Neonatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Tereza Lamberska
- Neonatology, General University Hospital in Prague, Prague, Czech Republic
| | - Janneke Dekker
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Stuart B Hooper
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Arjan B Te Pas
- Neonatology, Leiden University Medical Center, Leiden, The Netherlands
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7
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Beyeler SA, Hodges MR, Huxtable AG. Impact of inflammation on developing respiratory control networks: rhythm generation, chemoreception and plasticity. Respir Physiol Neurobiol 2020; 274:103357. [PMID: 31899353 DOI: 10.1016/j.resp.2019.103357] [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] [Received: 07/31/2019] [Revised: 11/17/2019] [Accepted: 12/02/2019] [Indexed: 10/25/2022]
Abstract
The respiratory control network in the central nervous system undergoes critical developmental events early in life to ensure adequate breathing at birth. There are at least three "critical windows" in development of respiratory control networks: 1) in utero, 2) newborn (postnatal day 0-4 in rodents), and 3) neonatal (P10-13 in rodents, 2-4 months in humans). During these critical windows, developmental processes required for normal maturation of the respiratory control network occur, thereby increasing vulnerability of the network to insults, such as inflammation. Early life inflammation (induced by LPS, chronic intermittent hypoxia, sustained hypoxia, or neonatal maternal separation) acutely impairs respiratory rhythm generation, chemoreception and increases neonatal risk of mortality. These early life impairments are also greater in young males, suggesting sex-specific impairments in respiratory control. Further, neonatal inflammation has a lasting impact on respiratory control by impairing adult respiratory plasticity. This review focuses on how inflammation alters respiratory rhythm generation, chemoreception and plasticity during each of the three critical windows. We also highlight the need for additional mechanistic studies and increased investigation into how glia (such as microglia and astrocytes) play a role in impaired respiratory control after inflammation. Understanding how inflammation during critical windows of development disrupt respiratory control networks is essential for developing better treatments for vulnerable neonates and preventing adult ventilatory control disorders.
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Affiliation(s)
- Sarah A Beyeler
- Department of Human Physiology, University of Oregon, Eugene, OR, 97403, United States
| | - Matthew R Hodges
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Adrianne G Huxtable
- Department of Human Physiology, University of Oregon, Eugene, OR, 97403, United States.
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8
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Wei W, Gao X, Zhao L, Zhuang J, Jiao Y, Xu F. Liquiritin apioside attenuates laryngeal chemoreflex but not mechanoreflex in rat pups. Am J Physiol Lung Cell Mol Physiol 2020; 318:L89-L97. [PMID: 31617735 PMCID: PMC6985871 DOI: 10.1152/ajplung.00306.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 10/10/2019] [Accepted: 10/10/2019] [Indexed: 02/08/2023] Open
Abstract
Liquiritin apioside (LA), a main flavonoid component of licorice, reportedly suppresses cough responses to inhalation of aerosolized capsaicin [CAP; a stimulant to transient receptor potential vanilloid 1 (TRPV1)] in conscious guinea pigs via acting on peripheral nerves. However, the evidence of LA having a direct effect on airway sensory fibers is lacking. Considering the important role laryngeal chemoreceptors and mechanoreceptors play in triggering apnea and cough, we studied whether LA suppressed the apneic responses to stimulation of these receptors via directly acting on the superior laryngeal nerve (SLN). Intralaryngeal delivery of chemical [CAP, HCl, and distilled water (DW)] and mechanical [an air-pulse (AP)] stimulations was applied in anesthetized rat pups to evoke the apnea. These stimuli were repeated after intralaryngeal LA treatment or peri-SLN LA treatment to determine the direct effect of LA on the SLN. Our results showed that all stimuli triggered an immediate apnea. Intralaryngeal LA treatment significantly attenuated the apneic response to chemical but not mechanical stimulations. The same attenuation was observed after peri-SLN LA treatment. Owing that TRPV1 receptors of laryngeal C fibers are responsible for the CAP-triggered apneas, the LA impact on the activity of laryngeal C neurons retrogradely traced by DiI was subsequently studied using a patch-clamp approach. LA pretreatment significantly altered the electrophysiological kinetics of CAP-induced currents in laryngeal C neurons by reducing their amplitudes, increasing the rise times, and prolonging the decay times. In conclusion, our results, for the first time, reveal that LA suppresses the laryngeal chemoreceptor-mediated apnea by directly acting on the SLN (TRPV1 receptors of laryngeal C fibers).
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Affiliation(s)
- Wan Wei
- Pathophysiology Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
- Graduate School, Beijing University of Chinese Medicine, Beijing, China
| | - Xiuping Gao
- Pathophysiology Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Lei Zhao
- Pathophysiology Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Jianguo Zhuang
- Pathophysiology Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Yang Jiao
- Dongfang Hospital Affiliated to Beijing University of Chinese Medicine, Beijing, China
| | - Fadi Xu
- Pathophysiology Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
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9
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Janes TA, Rousseau JP, Fournier S, Kiernan EA, Harris MB, Taylor BE, Kinkead R. Development of central respiratory control in anurans: The role of neurochemicals in the emergence of air-breathing and the hypoxic response. Respir Physiol Neurobiol 2019; 270:103266. [PMID: 31408738 PMCID: PMC7476778 DOI: 10.1016/j.resp.2019.103266] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 07/10/2019] [Accepted: 08/05/2019] [Indexed: 01/08/2023]
Abstract
Physiological and environmental factors impacting respiratory homeostasis vary throughout the course of an animal's lifespan from embryo to adult and can shape respiratory development. The developmental emergence of complex neural networks for aerial breathing dates back to ancestral vertebrates, and represents the most important process for respiratory development in extant taxa ranging from fish to mammals. While substantial progress has been made towards elucidating the anatomical and physiological underpinnings of functional respiratory control networks for air-breathing, much less is known about the mechanisms establishing these networks during early neurodevelopment. This is especially true of the complex neurochemical ensembles key to the development of air-breathing. One approach to this issue has been to utilize comparative models such as anuran amphibians, which offer a unique perspective into early neurodevelopment. Here, we review the developmental emergence of respiratory behaviours in anuran amphibians with emphasis on contributions of neurochemicals to this process and highlight opportunities for future research.
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Affiliation(s)
- Tara A Janes
- Department of Pediatrics, Université Laval & Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, QC, Canada
| | - Jean-Philippe Rousseau
- Department of Pediatrics, Université Laval & Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, QC, Canada
| | - Stéphanie Fournier
- Department of Pediatrics, Université Laval & Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, QC, Canada
| | - Elizabeth A Kiernan
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison Wisconsin, USA
| | - Michael B Harris
- Department of Biological Sciences, California State University Long Beach, California, USA
| | - Barbara E Taylor
- Department of Biological Sciences, California State University Long Beach, California, USA
| | - Richard Kinkead
- Department of Pediatrics, Université Laval & Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, QC, Canada.
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10
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Maternal thyroid hormone deficiency and cardiorespiratory disorder in rat pups. Exp Neurol 2019; 320:112960. [DOI: 10.1016/j.expneurol.2019.112960] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 05/08/2019] [Accepted: 05/16/2019] [Indexed: 11/17/2022]
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11
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Ramirez SC, Koschnitzky JE, Youngquist TM, Baertsch NA, Smith CV, Ramirez JM. Perinatal Breathing Patterns and Survival in Mice Born Prematurely and at Term. Front Physiol 2019; 10:1113. [PMID: 31543825 PMCID: PMC6728753 DOI: 10.3389/fphys.2019.01113] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 08/12/2019] [Indexed: 11/29/2022] Open
Abstract
Infants born prematurely, often associated with maternal infection, frequently exhibit breathing instabilities that require resuscitation. We hypothesized that breathing patterns during the first hour of life would be predictive of survival in an animal model of prematurity. Using plethysmography, we measured breathing patterns during the first hour after birth in mice born at term (Term 19.5), delivered prematurely on gestational day 18.5 following administration of low-dose lipopolysaccharide (LPS; 0.14 mg/kg) to pregnant dams (LPS 18.5), or delivered on gestational day 18.7 or 17.5 by caesarian section (C-S 18.5 and C-S 17.5, respectively). Our experimental approach allowed us to dissociate effects caused by inflammation, from effects due to premature birth in the absence of an inflammatory response. C-S 17.5 mice did not survive, whereas mortality was not increased in C-S 18.5 mice. However, in premature pups born at the same gestational age (day 18.5) in response to maternal LPS injection, mortality was significantly increased. Overall, mice that survived had higher birth weights and showed eupneic or gasping activity that was able to transition to normal breathing. Some mice also exhibited a “saw tooth” breathing pattern that was able to transition into eupnea during the first hour of life. In contrast, mice that did not survive showed distinct, large amplitude, long-lasting breaths that occurred at low frequency and did not transition into eupnea. This breathing pattern was only observed during the first hour of life and was more prevalent in LPS 18.5 and C-S 18.5 mice. Indeed, breath tidal volumes were higher in inflammation-induced premature pups than in pups delivered via C-section at equivalent gestational ages, whereas breathing frequencies were low in both LPS-induced and C-section-induced premature pups. We conclude that a breathing pattern characterized by low frequency and large tidal volume is a predictor for the failure to survive, and that these characteristics are more often seen when prematurity occurs in the context of maternal inflammation. Further insights into the mechanisms that generate these breathing patterns and how they transition to normal breathing may facilitate development of novel strategies to manage premature birth in humans.
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Affiliation(s)
- Sanja C Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Jenna E Koschnitzky
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Tiffany M Youngquist
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Nathan A Baertsch
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Charles V Smith
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States.,Department of Neurological Surgery, University of Washington School of Medicine, Seattle, WA, United States
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12
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Baldy C, Fournier S, Boisjoly-Villeneuve S, Tremblay MÈ, Kinkead R. The influence of sex and neonatal stress on medullary microglia in rat pups. Exp Physiol 2018; 103:1192-1199. [PMID: 29920821 DOI: 10.1113/ep087088] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 06/13/2018] [Indexed: 12/16/2022]
Abstract
NEW FINDINGS What is the central question of the study? Does neonatal stress, in the form of neonatal maternal separation, influence the maturation of microglial density, morphology and neuronal signalling in medullary regions regulating cardiorespiratory function in rat pups? What is the main finding and its importance? Using Iba-1 immunohistochemistry, we show that neonatal maternal separation augments microglial density and the proportion of cells with an amoeboid morphology in the medulla. Although the current understanding of the effect of early life stress on medullary development is relatively limited, these data show that within this area, microglia are affected by neonatal stress. Microglia could therefore be important effectors in cardiorespiratory disorders resulting from maternal separation. ABSTRACT Neonatal stress has wide-ranging consequences for the developing brain, including the medullary cardiorespiratory network. In rat pups, the reflexive cardiorespiratory inhibition triggered by the presence of liquids near the larynx is augmented by neonatal maternal separation (NMS), especially in males. Sex-specific enhancement of synaptic connectivity by NMS might explain this cardiorespiratory dysfunction. Microglia influence the formation, maturation, activity and elimination of developing synapses, but their role in the wiring of medullary networks is unknown. Owing to their sensitivity to sex hormones and stress hormones, microglial dysfunction could contribute to the abnormal cardiorespiratory phenotype observed in NMS pups. Here, we first used ionized calcium-binding adapter molecule-1 (Iba-1) immunolabelling to compare the density and morphology of microglia in the medulla of male versus female rat pups (14-15 days old) that were either undisturbed or subjected to NMS (3 h day-1 ; postnatal days 3-12). Neonatal maternal separation augmented the density of Iba-1+ cells (caudal region of the NTS), increased the size of the soma and reduced the arborization area (especially in the dorsal motor nucleus of the vagus). Sex-based differences were not observed. Given that the actions of microglia are regulated by neuronal fractalkine (CX3 CL1 ), we then used western blot analysis to compare the expression of CX3 CL1 and its microglial receptor (CX3 CR1 ) in medullary homogenates from control and NMS pups. Although CX3 CR1 expression was 59% greater in males versus females, NMS had no effect on CX3 CL1 /CX3 CR1 signalling. Given that an amoeboid morphology reflects an immature phenotype in developing microglia, NMS could interfere with synaptic pruning via a different mechanism.
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Affiliation(s)
- Cécile Baldy
- Département de Pédiatrie, Centre de Recherche de l'Institut Universitaire de Cardiologie et Pneumologie de Québec, Université Laval, Québec, QC, Canada
| | - Stéphanie Fournier
- Département de Pédiatrie, Centre de Recherche de l'Institut Universitaire de Cardiologie et Pneumologie de Québec, Université Laval, Québec, QC, Canada
| | - Samuel Boisjoly-Villeneuve
- Département de Pédiatrie, Centre de Recherche de l'Institut Universitaire de Cardiologie et Pneumologie de Québec, Université Laval, Québec, QC, Canada.,Département de Médecine Moléculaire, Centre de Recherche du CHU de Québec, Université Laval, Québec, QC, Canada
| | - Marie-Ève Tremblay
- Département de Médecine Moléculaire, Centre de Recherche du CHU de Québec, Université Laval, Québec, QC, Canada
| | - Richard Kinkead
- Département de Pédiatrie, Centre de Recherche de l'Institut Universitaire de Cardiologie et Pneumologie de Québec, Université Laval, Québec, QC, Canada
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