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Kim TH, Lee H, Woo S, Lee H, Park J, Fond G, Boyer L, Hahn JW, Kang J, Yon DK. Prenatal and postnatal factors associated with sudden infant death syndrome: an umbrella review of meta-analyses. World J Pediatr 2024; 20:451-460. [PMID: 38684567 DOI: 10.1007/s12519-024-00806-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 03/11/2024] [Indexed: 05/02/2024]
Abstract
BACKGROUND Comprehensive quantitative evidence on the risk and protective factors for sudden infant death syndrome (SIDS) effects is lacking. We investigated the risk and protective factors related to SIDS. METHODS We conducted an umbrella review of meta-analyses of observational and interventional studies assessing SIDS-related factors. PubMed/MEDLINE, Embase, EBSCO, and Google Scholar were searched from inception until January 18, 2023. Data extraction, quality assessment, and certainty of evidence were assessed by using A Measurement Tool Assessment Systematic Reviews 2 following PRISMA guidelines. According to observational evidence, credibility was graded and classified by class and quality of evidence (CE; convincing, highly suggestive, suggestive, weak, or not significant). Our study protocol was registered with PROSPERO (CRD42023458696). The risk and protective factors related to SIDS are presented as equivalent odds ratios (eORs). RESULTS We identified eight original meta-analyses, including 152 original articles, covering 12 unique risk and protective factors for SIDS across 21 countries/regions and five continents. Several risk factors, including prenatal drug exposure [eOR = 7.84 (95% CI = 4.81-12.79), CE = highly suggestive], prenatal opioid exposure [9.55 (95% CI = 4.87-18.72), CE = suggestive], prenatal methadone exposure [9.52 (95% CI = 3.34-27.10), CE = weak], prenatal cocaine exposure [4.38 (95% CI = 1.95-9.86), CE = weak], prenatal maternal smoking [2.25 (95% CI = 1.95-2.60), CE = highly suggestive], postnatal maternal smoking [1.97 (95% CI = 1.75-2.22), CE = weak], bed sharing [2.89 (95% CI = 1.81-4.60), CE = weak], and infants found with heads covered by bedclothes after last sleep [11.01 (95% CI = 5.40-22.45), CE = suggestive], were identified. On the other hand, three protective factors, namely, breastfeeding [0.57 (95% CI = 0.39-0.83), CE = non-significant], supine sleeping position [0.48 (95% CI = 0.37-0.63), CE = suggestive], and pacifier use [0.44 (95% CI = 0.30-0.65), CE = weak], were also identified. CONCLUSIONS Based on the evidence, we propose several risk and protective factors for SIDS. This study suggests the need for further studies on SIDS-related factors supported by weak credibility, no association, or a lack of adequate research.
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Affiliation(s)
- Tae Hyeon Kim
- Department of Medicine, Kyung Hee University College of Medicine, Seoul, South Korea
| | - Hyeri Lee
- Center for Digital Health, Medical Science Research Institute, Kyung Hee University College of Medicine, Seoul, South Korea
- Department of Regulatory Science, Kyung Hee University, Seoul, South Korea
| | - Selin Woo
- Center for Digital Health, Medical Science Research Institute, Kyung Hee University College of Medicine, Seoul, South Korea
| | - Hayeon Lee
- Center for Digital Health, Medical Science Research Institute, Kyung Hee University College of Medicine, Seoul, South Korea
- Department of Biomedical Engineering, Kyung Hee University, Yongin, South Korea
| | - Jaeyu Park
- Center for Digital Health, Medical Science Research Institute, Kyung Hee University College of Medicine, Seoul, South Korea
- Department of Regulatory Science, Kyung Hee University, Seoul, South Korea
| | - Guillaume Fond
- CEReSS-Health Service Research and Quality of Life Center, Assistance Publique des Hôpitaux de Marseille, Aix-Marseille University, Marseille, France
| | - Laurent Boyer
- CEReSS-Health Service Research and Quality of Life Center, Assistance Publique des Hôpitaux de Marseille, Aix-Marseille University, Marseille, France
| | - Jong Woo Hahn
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, South Korea
- Department of Pediatrics, Seoul National University Bundang Hospital, Seongnam, South Korea
| | - Jiseung Kang
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, 149 13th Street, Room 4140, Charlestown, Boston, MA, USA.
- Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA.
| | - Dong Keon Yon
- Department of Medicine, Kyung Hee University College of Medicine, Seoul, South Korea.
- Center for Digital Health, Medical Science Research Institute, Kyung Hee University College of Medicine, Seoul, South Korea.
- Department of Regulatory Science, Kyung Hee University, Seoul, South Korea.
- Department of Pediatrics, Kyung Hee University Medical Center, Kyung Hee University College of Medicine, 23 Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, South Korea.
- Department of Precision Medicine, Kyung Hee University College of Medicine, Seoul, South Korea.
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Vincent A, Chu NT, Shah A, Avanthika C, Jhaveri S, Singh K, Limaye OM, Boddu H. Sudden Infant Death Syndrome: Risk Factors and Newer Risk Reduction Strategies. Cureus 2023; 15:e40572. [PMID: 37465778 PMCID: PMC10351748 DOI: 10.7759/cureus.40572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2023] [Indexed: 07/20/2023] Open
Abstract
Sudden infant death syndrome (SIDS) continues to be one of the top causes of infant death in the U.S. Despite significant public health initiatives focused on high-risk populations to enhance sleep environments and techniques. The SIDS rate has remained stable in recent years. Risk factors and newer risk reduction strategies for SIDS are the focus of this review article. We conducted a comprehensive literature search on Medline, Cochrane, Embase, and Google Scholar until July 2022. The following search strings and Medical Subject Heading (MeSH) terms were used: "SIDS," "Sudden Infant Death" and "SUID". We explored the literature on SIDS for its epidemiology, pathophysiology, the role of various etiologies and their influence, associated complications leading to SIDS, and preventive and treatment modalities. Despite a more than 50% drop-in rates since the start of the "Back to Sleep" campaign in 1994, sudden infant death syndrome (SIDS) continues to be the top cause of post-neonatal mortality in the United States, despite continued educational initiatives that support safe sleep and other risk reduction strategies. The new American Academy of Pediatrics guidelines for lowering the risk of SIDS include a lot of emphasis on sleeping habits, bedding, and environment but also include elements that are frequently ignored (i.e., prenatal care, smoking, alcohol and drug use, and childhood vaccinations). This study highlights these less-frequently discussed aspects and identifies treatments that have produced beneficial behavioral shifts that benefit newborns as well as their mothers' health and wellbeing.
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Affiliation(s)
- Anita Vincent
- Medicine and Surgery, Karnataka Institute of Medical Sciences, Hubli, IND
| | - Ngan Thy Chu
- Paediatrics, City Children's Hospital, Ho Chi Minh city, VNM
| | - Aashka Shah
- Paediatrics and Child Health, Pramukhswami Medical College, Karamsad, Anand, IND
| | - Chaithanya Avanthika
- Pediatrics, Icahn School of Medicine at Mount Sinai, Queens Hospital Center, New York City, USA
- Medicine and Surgery, Karnataka Institute of Medical Sciences, Hubli, IND
| | - Sharan Jhaveri
- Medicine and Surgery, Smt. Nathiba Hargovandas Lakhmichand Municipal Medical College (NHLMMC), Ahmedabad, IND
| | - Kunika Singh
- Paediatrics, Xinjiang Medical University, Xinjiang, CHN
| | - Om M Limaye
- Paediatrics, Lokmanya Tilak Municipal Medical College and Sion Hospital, Mumbai, IND
| | - Himasaila Boddu
- Paediatrics, Dr. Pinnamaneni Siddartha Institute of Medical Sciences and Research Foundation, Krishna, IND
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3
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Heller NA, Shrestha H, Morrison DG, Daigle KM, Logan BA, Paul JA, Brown MS, Hayes MJ. Neonatal sleep development and early learning in infants with prenatal opioid exposure. ADVANCES IN CHILD DEVELOPMENT AND BEHAVIOR 2021; 60:199-228. [PMID: 33641794 DOI: 10.1016/bs.acdb.2020.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The aim of this chapter is to examine the role of sleep and cognition in the context of the cumulative risk model examining samples of at-risk infants and maternal-infant dyads. The cumulative risk model posits that non-optimal developmental outcomes are the result of multiple factors in a child's life including, but not limited to, prenatal teratogenic exposures, premature birth, family socioeconomic status, parenting style and cognitions as well as the focus of this volume, sleep. We highlight poor neonatal sleep as both an outcome of perinatal risk as well as a risk factor to developing attentional and cognitive capabilities during early childhood. Outcomes associated with and contributing to poor sleep and cognition during infancy are examined in relation to other known risks in our clinical population. Implications of this research and recommendations for interventions for this population are provided.
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Affiliation(s)
- Nicole A Heller
- Department of Psychology, Siena College, Loudonville, NY, United States
| | - Hira Shrestha
- Department of Pediatrics, Boston Medical Center, Boston, MA, United States
| | - Deborah G Morrison
- Department of Psychiatry, University of Florida, Gainesville, FL, United States
| | - Katrina M Daigle
- Department of Psychology, Suffolk University, Boston, MA, United States
| | - Beth A Logan
- Hillman Center for Pediatric Transplantation, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, United States
| | - Jonathan A Paul
- Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, ME, United States
| | - Mark S Brown
- Department of Pediatrics, Northern Light Eastern Maine Medical Center, Bangor, ME, United States
| | - Marie J Hayes
- Department of Psychology and Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, ME, United States.
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4
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Stonebridge R, Taliano RJ, Velilla TD, Anthony DC. Hypertrophy of the Anterior External Arcuate Fasciculus: A Rare Variant With Implications for the Development of the Arcuate Nucleus. Front Neuroanat 2020; 14:595500. [PMID: 33328906 PMCID: PMC7729007 DOI: 10.3389/fnana.2020.595500] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 10/27/2020] [Indexed: 11/17/2022] Open
Abstract
A rare anatomic variant of a markedly enlarged anterior external arcuate fasciculus (AEAF) on the ventral medullary surface is reported and compared to two controls. The hypertrophic AEAF was nine times larger in diameter than normal, whereas the arcuate nucleus (AN) and inferior olivary nucleus (ION) appeared histologically normal in size and neuronal distribution, and morphometric analysis of the AN confirmed that it was within the normal range. Calbindin-2 (calretinin, CALB2) expression was identified in the AN and in the fibers of the normal AEAF. The hypertrophic AEAF did not contain calbindin-2–expressing fibers. CALB2 expression was also present in the ventrolateral portion of the ION, both in the index case and in one of the control cases. The origin of the additional fibers was not identified; however, the potential origin of these fibers and its implications for the development of the AEAF are discussed.
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Affiliation(s)
- Renee Stonebridge
- Department of Pathology and Laboratory Medicine, Lifespan Academic Medical Center, Providence, RI, United States.,Department of Pathology and Laboratory Medicine, Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - Ross J Taliano
- Department of Pathology and Laboratory Medicine, Lifespan Academic Medical Center, Providence, RI, United States.,Department of Pathology and Laboratory Medicine, Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - Terra D Velilla
- Department of Pathology and Laboratory Medicine, Lifespan Academic Medical Center, Providence, RI, United States
| | - Douglas C Anthony
- Department of Pathology and Laboratory Medicine, Lifespan Academic Medical Center, Providence, RI, United States.,Department of Pathology and Laboratory Medicine, Warren Alpert Medical School of Brown University, Providence, RI, United States.,Department of Neurology, Warren Alpert Medical School of Brown University, Providence, RI, United States
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5
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Erickson JT. Central serotonin and autoresuscitation capability in mammalian neonates. Exp Neurol 2020; 326:113162. [DOI: 10.1016/j.expneurol.2019.113162] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 11/04/2019] [Accepted: 12/23/2019] [Indexed: 01/08/2023]
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Abstract
A wide variety of neuropathological abnormalities have been investigated in infants who have died of sudden infant death syndrome (SIDS). Issues which detracted from early studies included failure to use uniform definitions of SIDS and lack of appropriately matched control populations. Development of the triple risk model focused attention on the concept of an inherent susceptibility to unexpected death in certain infants, with research demonstrating a role for the neurotransmitter serotonin within the brainstem. However, it now appears that neuropathological abnormalities in SIDS infants are more complex than a simple serotonergic deficiency in certain medullary nuclei but instead could involve failure of an integrated network of neurochemical transmitters in a variety of subcortical locations. The following overview examines recent research developments looking particularly at the potential role of the peptide neurotransmitter substance P and its neurokinin-1 receptor in multiple nuclei within the brainstem, asymmetry and microdysgenesis of the hippocampus, and decreased orexin levels within dorsomedial, perifornical, and lateral levels in the hypothalamus. Whether such research will lead to identifiable biomarker for infants at risk of SIDS is yet to be established. Use of standardized and consistent methods of classifying and categorizing infant deaths will be pivotal in generating reproducible research results.
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Affiliation(s)
- Fiona M Bright
- 1 School of Medicine, University of Adelaide, Adelaide, South Australia, Australia
| | - Robert Vink
- 2 Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, Australia
| | - Roger W Byard
- 1 School of Medicine, University of Adelaide, Adelaide, South Australia, Australia
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7
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McIntosh C, Trenholme A, Stewart J, Vogel A. Evaluation of a sudden unexpected death in infancy intervention programme aimed at improving parental awareness of risk factors and protective infant care practices. J Paediatr Child Health 2018; 54:377-382. [PMID: 29125216 DOI: 10.1111/jpc.13772] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Revised: 08/23/2017] [Accepted: 09/03/2017] [Indexed: 11/29/2022]
Abstract
AIM Sudden unexpected death in infancy (SUDI) rates for Māori and Pacific infants remain higher than for other ethnic groups in New Zealand and bed-sharing is a major risk factor when there is smoking exposure in pregnancy. Sleep space programmes of education and Pēpi-Pod baby beds require evaluation. METHODS Two hundred and forty Māori and Pacific women and infants were randomised 1:1, to the Pēpi-Pod sleep space programme, or to a control group with 'usual care'. When infants were under 2 weeks of age, baseline interviews occurred, followed up by interviews at 2 and 4 months of age to assess safe sleep knowledge, infant care practices and Pēpi-Pod use and acceptability. All participants were offered a New Zealand Standard approved portable cot. RESULTS At baseline, 25% of babies did not have a baby bed. Knowledge of smoking and bed-sharing as SUDI risks improved at follow-up in both groups. One quarter regularly bed-shared at follow-up in both groups. Intention to bed-share was a strong predictor of subsequent behaviour. Pēpi-Pods were regularly used by 46% at 2 months and 16% at 4 months follow-up. CONCLUSIONS Bed-sharing and knowledge improvement were similar irrespective of group. It is likely that the impact of the intervention was reduced because the control group received better support than 'usual care' and all participants had a baby bed. New Zealand SUDI rates have declined since sleep space programmes have been available. Sleep space programmes should be prioritised for those with modifiable SUDI risk.
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Affiliation(s)
- Christine McIntosh
- Primary Health and Community Services, Counties Manukau Health, Auckland, New Zealand.,Department of Paediatrics: Child and Youth Health, University of Auckland, Auckland, New Zealand
| | - Adrian Trenholme
- Department of Paediatrics: Child and Youth Health, University of Auckland, Auckland, New Zealand.,Department of Paediatrics, Counites Manukau Health, Auckland, New Zealand
| | | | - Alison Vogel
- Department of Paediatrics, Counites Manukau Health, Auckland, New Zealand
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8
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Langer TM, Neumueller SE, Crumley E, Burgraff NJ, Talwar S, Hodges MR, Pan L, Forster HV. Ventilation and neurochemical changes during µ-opioid receptor activation or blockade of excitatory receptors in the hypoglossal motor nucleus of goats. J Appl Physiol (1985) 2017; 123:1532-1544. [PMID: 28839004 DOI: 10.1152/japplphysiol.00592.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Neuromodulator interdependence posits that changes in one or more neuromodulators are compensated by changes in other modulators to maintain stability in the respiratory control network. Herein, we studied compensatory neuromodulation in the hypoglossal motor nucleus (HMN) after chronic implantation of microtubules unilaterally ( n = 5) or bilaterally ( n = 5) into the HMN. After recovery, receptor agonists or antagonists in mock cerebrospinal fluid (mCSF) were dialyzed during the awake and non-rapid eye movement (NREM) sleep states. During day studies, dialysis of the µ-opioid inhibitory receptor agonist [d-Ala2, N-MePhe4, Gly-ol]enkephalin (DAMGO; 100 µM) decreased pulmonary ventilation (V̇i), breathing frequency ( f), and genioglossus (GG) muscle activity but did not alter neuromodulators measured in the effluent mCSF. However, neither unilateral dialysis of a broad spectrum muscarinic receptor antagonist (atropine; 50 mM) nor unilateral or bilateral dialysis of a mixture of excitatory receptor antagonists altered V̇i or GG activity, but all of these did increase HMN serotonin (5-HT) levels. Finally, during night studies, DAMGO and excitatory receptor antagonist decreased ventilatory variables during NREM sleep but not during wakefulness. These findings contrast with previous dialysis studies in the ventral respiratory column (VRC) where unilateral DAMGO or atropine dialysis had no effects on breathing and bilateral DAMGO or unilateral atropine increased V̇i and f and decreased GABA or increased 5-HT, respectively. Thus we conclude that the mechanisms of compensatory neuromodulation are less robust in the HMN than in the VRC under physiological conditions in adult goats, possibly because of site differences in the underlying mechanisms governing neuromodulator release and consequently neuronal activity, and/or responsiveness of receptors to compensatory neuromodulators. NEW & NOTEWORTHY Activation of inhibitory µ-opioid receptors in the hypoglossal motor nucleus decreased ventilation under physiological conditions and did not affect neurochemicals in effluent dialyzed mock cerebral spinal fluid. These findings contrast with studies in the ventral respiratory column where unilateral [d-Ala2, N-MePhe4, Gly-ol]enkephalin (DAMGO) had no effects on ventilation and bilateral DAMGO or unilateral atropine increased ventilation and decreased GABA or increased serotonin, respectively. Our data support the hypothesis that mechanisms that govern local compensatory neuromodulation within the brain stem are site specific under physiological conditions.
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Affiliation(s)
- Thomas M Langer
- Department of Physiology, Medical College of Wisconsin , Milwaukee, Wisconsin
| | | | - Emma Crumley
- Department of Physiology, Medical College of Wisconsin , Milwaukee, Wisconsin
| | - Nicholas J Burgraff
- Department of Physiology, Medical College of Wisconsin , Milwaukee, Wisconsin
| | - Sawan Talwar
- Department of Physiology, Medical College of Wisconsin , Milwaukee, Wisconsin
| | - Matthew R Hodges
- Department of Physiology, Medical College of Wisconsin , Milwaukee, Wisconsin.,Neuroscience Research Center, Medical College of Wisconsin , Milwaukee, Wisconsin
| | - Lawrence Pan
- Department of Physical Therapy, Marquette University , Milwaukee, Wisconsin
| | - Hubert V Forster
- Department of Physiology, Medical College of Wisconsin , Milwaukee, Wisconsin.,Neuroscience Research Center, Medical College of Wisconsin , Milwaukee, Wisconsin.,Zablocki Veterans Affairs Medical Center , Milwaukee, Wisconsin
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Bright FM, Byard RW, Vink R, Paterson DS. Medullary Serotonin Neuron Abnormalities in an Australian Cohort of Sudden Infant Death Syndrome. J Neuropathol Exp Neurol 2017; 76:864-873. [PMID: 28922849 DOI: 10.1093/jnen/nlx071] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Serotonin (5-hydroxytryptamine [5-HT]) neurons in the medulla oblongata project extensively to key autonomic and respiratory nuclei in the brainstem and spinal cord regulating critical homeostatic functions. Multiple abnormalities in markers of 5-HT function in the medulla in sudden infant death syndrome (SIDS) have been reported, informing the hypothesis that at least a subset of SIDS cases is caused by deficits in 5-HT function resulting in impaired homeostatic responses to potentially life-threatening events during sleep. To investigate medullary 5-HT defects in SIDS further, we undertook qualitative analysis immunohistochemical assessment of 5-HT neuron expression within the medulla of SIDS infants (n41) and nonSIDS controls (n = 28) in an independent cohort from Forensic Science South Australia. Compared with controls SIDS cases had significantly higher 5-HT neuron numbers and density in addition to significantly altered 5-HT neuron morphology. Thus, for the first time, we replicated and corroborated previous observations of a significant abnormality in medullary 5-HT neuron expression in SIDS in a separate independent SIDS cohort. This study further supports the hypothesis that medullary 5-HT defects contribute to the pathogenesis of a subset of SIDS victims and provides additional evidence of a more complex abnormality in 5-HT neuron dysfunction specifically within the different caudal and rostral medullary 5-HT domains.
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Affiliation(s)
- Fiona M Bright
- Faculty of Health and Medical Science, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia; Department of Pathology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts; Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, Australia
| | - Roger W Byard
- Faculty of Health and Medical Science, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia; Department of Pathology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts; Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, Australia
| | - Robert Vink
- Faculty of Health and Medical Science, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia; Department of Pathology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts; Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, Australia
| | - David S Paterson
- Faculty of Health and Medical Science, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia; Department of Pathology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts; Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, Australia
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10
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Wang X, Guo R, Zhao W, Pilowsky PM. Medullary mediation of the laryngeal adductor reflex: A possible role in sudden infant death syndrome. Respir Physiol Neurobiol 2016; 226:121-7. [PMID: 26774498 DOI: 10.1016/j.resp.2016.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 01/08/2016] [Accepted: 01/10/2016] [Indexed: 10/22/2022]
Abstract
The laryngeal adductor reflex (LAR) is a laryngeal protective reflex. Vagal afferent polymodal sensory fibres that have cell bodies in the nodose ganglion, originate in the sub-glottal area of the larynx and upper trachea. These polymodal sensory fibres respond to mechanical or chemical stimuli. The central axons of these sensory vagal neurons terminate in the dorsolateral subnuclei of the tractus solitarius in the medulla oblongata. The LAR is a critical, reflex in the pathways that play a protective role in the process of ventilation, and the sychronisation of ventilation with other activities that are undertaken by the oropharyngeal systems including: eating, speaking and singing. Failure of the LAR to operate properly at any time after birth can lead to SIDS, pneumonia or death. Despite the critical nature of this reflex, very little is known about the central pathways and neurotransmitters involved in the management of the LAR and any disorders associated with its failure to act properly. Here, we review current knowledge concerning the medullary nuclei and neurochemicals involved in the LAR and propose a potential neural pathway that may facilitate future SIDS research.
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Affiliation(s)
- Xiaolu Wang
- Institute of Clinical Pharmacology, Qilu Hospital of Shandong University, Jinan, China
| | - Ruichen Guo
- Institute of Clinical Pharmacology, Qilu Hospital of Shandong University, Jinan, China
| | - Wenjing Zhao
- Heart Research Institute, University of Sydney,7 Eliza St., Newtown, Australia
| | - Paul M Pilowsky
- Heart Research Institute, University of Sydney,7 Eliza St., Newtown, Australia.
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11
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Fleming PJ, Blair PS, Pease A. Sudden unexpected death in infancy: aetiology, pathophysiology, epidemiology and prevention in 2015. Arch Dis Child 2015; 100:984-8. [PMID: 25699563 DOI: 10.1136/archdischild-2014-306424] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 01/28/2015] [Indexed: 11/04/2022]
Abstract
Despite the fall in numbers of unexpected infant deaths that followed the 'Back to Sleep' campaigns in the early 1990 s in the UK and many other countries, such deaths remain one of the largest single groups of deaths in the postneonatal period in many Western countries. Changes in the ways in which unexpected infant deaths are categorised by pathologists and coroners, and increasing reluctance to use the term 'sudden infant death syndrome', make assessment of nationally and internationally collected data on incidence potentially inaccurate and confusing. In this paper, we review current understanding of the epidemiology and aetiology of unexpected deaths in infancy, and current hypotheses on the pathophysiology of the processes that may lead to death. We also review interventions that have been adopted, with variable degrees of effectiveness in efforts to reduce the numbers of deaths, and new approaches that offer the possibility of prevention in the future.
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Affiliation(s)
- Peter J Fleming
- Centre for Child and Adolescent Health, University of Bristol. St Michaels Hospital, Bristol, UK
| | - Peter S Blair
- Centre for Child and Adolescent Health, University of Bristol. St Michaels Hospital, Bristol, UK
| | - Anna Pease
- Centre for Child and Adolescent Health, University of Bristol. St Michaels Hospital, Bristol, UK
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12
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Effect of Systemic Application of 5-Hydroxytryptamine on Hypoglossal Nerve Discharge in Anesthetized Rats. J Mol Neurosci 2015; 57:435-45. [DOI: 10.1007/s12031-015-0590-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 05/25/2015] [Indexed: 01/12/2023]
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13
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Ostrowski TD, Ostrowski D, Hasser EM, Kline DD. Depressed GABA and glutamate synaptic signaling by 5-HT1A receptors in the nucleus tractus solitarii and their role in cardiorespiratory function. J Neurophysiol 2014; 111:2493-504. [PMID: 24671532 PMCID: PMC4044435 DOI: 10.1152/jn.00764.2013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 03/19/2014] [Indexed: 11/22/2022] Open
Abstract
Serotonin (5-HT), and its 5-HT1A receptor (5-HT1AR) subtype, is a powerful modulator of the cardiorespiratory system and its sensory reflexes. The nucleus tractus solitarii (nTS) serves as the first central station for visceral afferent integration and is critical for cardiorespiratory reflex responses. However, the physiological and synaptic role of 5-HT1ARs in the nTS is relatively unknown. In the present study, we examined the distribution and modulation of 5-HT1ARs on cardiorespiratory and synaptic parameters in the nTS. 5-HT1ARs were widely distributed to cell bodies within the nTS but not synaptic terminals. In anesthetized rats, activation of 5-HT1ARs by microinjection of the 5-HT1AR agonist 8-OH-DPAT into the caudal nTS decreased minute phrenic neural activity via a reduction in phrenic amplitude. In brain stem slices, 8-OH-DPAT decreased the amplitude of glutamatergic tractus solitarii-evoked excitatory postsynaptic currents, and reduced overall spontaneous excitatory nTS network activity. These effects persisted in the presence of GABAA receptor blockade and were antagonized by coapplication of 5-HT1AR blocker WAY-100135. 5-HT1AR blockade alone had no effect on tractus solitarii-evoked excitatory postsynaptic currents, but increased excitatory network activity. On the other hand, GABAergic nTS-evoked inhibitory postsynaptic currents did not change by activation of the 5-HT1ARs, but spontaneous inhibitory nTS network activity decreased. Blocking 5-HT1ARs tended to increase nTS-evoked inhibitory postsynaptic currents and inhibitory network activity. Taken together, 5-HT1ARs in the caudal nTS decrease breathing, likely via attenuation of afferent transmission, as well as overall nTS network activity.
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Affiliation(s)
- Tim D Ostrowski
- Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Daniela Ostrowski
- Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Eileen M Hasser
- Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - David D Kline
- Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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The physiological determinants of sudden infant death syndrome. Respir Physiol Neurobiol 2013; 189:288-300. [PMID: 23735486 DOI: 10.1016/j.resp.2013.05.032] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 05/19/2013] [Accepted: 05/27/2013] [Indexed: 01/08/2023]
Abstract
It is well-established that environmental and biological risk factors contribute to Sudden Infant Death Syndrome (SIDS). There is also growing consensus that SIDS requires the intersection of multiple risk factors that result in the failure of an infant to overcome cardio-respiratory challenges. Thus, the critical next steps in understanding SIDS are to unravel the physiological determinants that actually cause the sudden death, to synthesize how these determinants are affected by the known risk factors, and to develop novel ideas for SIDS prevention. In this review, we will examine current and emerging perspectives related to cardio-respiratory dysfunctions in SIDS. Specifically, we will review: (1) the role of the preBötzinger complex (preBötC) as a multi-functional network that is critically involved in the failure to adequately respond to hypoxic and hypercapnic challenges; (2) the potential involvement of the preBötC in the gender and age distributions that are characteristic for SIDS; (3) the link between SIDS and prematurity; and (4) the potential relationship between SIDS, auditory function, and central chemosensitivity. Each section underscores the importance of marrying the epidemiological and pathological data to experimental data in order to understand the physiological determinants of this syndrome. We hope that a better understanding will lead to novel ways to reduce the risk to succumb to SIDS.
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15
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Rand CM, Patwari PP, Carroll MS, Weese-Mayer DE. Congenital central hypoventilation syndrome and sudden infant death syndrome: disorders of autonomic regulation. Semin Pediatr Neurol 2013; 20:44-55. [PMID: 23465774 DOI: 10.1016/j.spen.2013.01.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Long considered a rare and unique disorder of respiratory control, congenital central hypoventilation syndrome has recently been further distinguished as a disorder of autonomic regulation. Similarly, more recent evidence suggests that sudden infant death syndrome is also a disorder of autonomic regulation. Congenital central hypoventilation syndrome typically presents in the newborn period with alveolar hypoventilation, symptoms of autonomic dysregulation and, in a subset of cases, Hirschsprung disease or tumors of neural crest origin or both. Genetic investigation identified PHOX2B, a crucial gene during early autonomic development, as disease defining for congenital central hypoventilation syndrome. Although sudden infant death syndrome is most likely defined by complex multifactorial genetic and environmental interactions, it is also thought to result from central deficits in the control of breathing and autonomic regulation. The purpose of this article is to review the current understanding of these autonomic disorders and discuss the influence of this information on clinical practice and future research directions.
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Affiliation(s)
- Casey M Rand
- Center for Autonomic Medicine in Pediatrics, Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
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16
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O'Leary CM, Jacoby PJ, Bartu A, D'Antoine H, Bower C. Maternal alcohol use and sudden infant death syndrome and infant mortality excluding SIDS. Pediatrics 2013; 131:e770-8. [PMID: 23439895 DOI: 10.1542/peds.2012-1907] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Improvements in the rate of infant mortality (death in first year of life) have not occurred in recent years. This study investigates the association between maternal alcohol-use disorder and sudden infant death syndrome (SIDS) and infant mortality not classified as SIDS using linked, population-based health and mortality data. METHODS Exposed mothers were identified through the presence of an International Classification of Diseases 9/10 alcohol diagnosis, a proxy for alcohol-use disorder, recorded on health, mental health, and/or drug and alcohol datasets (1983-2005). Comparison mothers without an alcohol diagnosis were frequency matched to exposed mothers on maternal age within maternal race and year of birth of their children. All offspring with their birth recorded on the Midwives Notification System compose the exposed (n = 21 841) and comparison (n = 56 054) cohorts. Cases of SIDS (n = 303) and infant mortality excluding SIDS (n = 598) were identified through linkage with the Western Australian Mortality Register. Analyses were conducted by using Cox regression and results presented as adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs). RESULTS The highest risk of SIDS occurred when a maternal alcohol diagnosis was recorded during pregnancy (aHR 6.92, 95% CI 4.02-11.90) or within 1 year postpregnancy (aHR 8.61, 95% CI 5.04-14.69). An alcohol diagnosis recorded during pregnancy more than doubled the risk of infant deaths (excluding SIDS) (aHR 2.35, 95% CI 1.45-3.83). Maternal alcohol-use disorder is attributable for at least 16.41% (95% CI 9.73%-23.69%) of SIDS and 3.40% (95% CI 2.28%-4.67%) of infant deaths not classified as SIDS. CONCLUSIONS Maternal alcohol-use disorder is a significant risk factor for SIDS and infant mortality excluding SIDS.
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Affiliation(s)
- Colleen M O'Leary
- Centre for Population Health Research, Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia.
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17
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Stéphan-Blanchard E, Bach V, Telliez F, Chardon K. Perinatal nicotine/smoking exposure and carotid chemoreceptors during development. Respir Physiol Neurobiol 2012; 185:110-9. [PMID: 22743051 DOI: 10.1016/j.resp.2012.06.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Revised: 06/19/2012] [Accepted: 06/20/2012] [Indexed: 11/26/2022]
Abstract
Tobacco smoking is still a common habit during pregnancy and is the most important preventable cause of many adverse perinatal outcomes. Prenatal smoking exposure can produce direct actions of nicotine in the fetus with the disruption of body and brain development, and actions on the maternal-fetal unit by causing repeated episodes of hypoxia and exposure to many toxic smoke products (such as carbon monoxide). Specifically, nicotine through binding to nicotinic acetylcholine receptors have ubiquitous effects and can affect carotid chemoreception development through structural, functional and neuroregulatory alterations of the neural circuits involved in the chemoafferent pathway, as well as by interfering with the postnatal resetting of the carotid bodies. Reduced carotid body chemosensitivity and tonic activity have thus been reported by the majority of the human and animal studies. This review focuses on the effects of perinatal exposure to tobacco smoke and nicotine on carotid chemoreceptor function during the developmental period. A description of the effects of smoking and nicotine on the control of breathing related to carotid body activity, and of the possible physiopathological mechanisms at the origin of these disturbances is presented.
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Affiliation(s)
- E Stéphan-Blanchard
- PériTox-INERIS Laboratory, Jules Verne University of Picardy, Amiens, France.
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18
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Tang S, Machaalani R, Waters KA. Expression of brain-derived neurotrophic factor and TrkB receptor in the sudden infant death syndrome brainstem. Respir Physiol Neurobiol 2011; 180:25-33. [PMID: 22020324 DOI: 10.1016/j.resp.2011.10.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 10/07/2011] [Accepted: 10/08/2011] [Indexed: 12/23/2022]
Abstract
This study compared the expression of BDNF (proBDNF and rhBDNF forms) and its receptor TrkB, in the medulla of sudden infant death syndrome (SIDS) infants and infants who died from known causes (non-SIDS). This study also evaluated these markers in association with SIDS clinical risk factors including, sleep position, cigarette smoke exposure and gender. Brainstem tissue was immunohistochemically stained and quantitative analyses were made for eight nuclei of the caudal and rostral medulla. Compared to non-SIDS, SIDS infants had lower rhBDNF in the caudal nucleus of the solitary tract and higher TrkB in the caudal dorsal motor nucleus of the vagus. Within the SIDS cohort, prone sleep position was associated with lower rhBDNF in the caudal arcuate nucleus, and cigarette smoke exposure was associated with lower rhBDNF and TrkB in the inferior olivary nucleus. Abnormal expression of BDNF and TrkB suggests that neuroprotective functions of the BDNF/TrkB system may be reduced in respiratory-related nuclei of SIDS infants.
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Affiliation(s)
- Samantha Tang
- Department of Paediatrics and Child Health, University of Sydney, NSW 2006, Australia; Bosch Institute, The University of Sydney, NSW 2006, Australia
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19
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Viemari JC, Garcia AJ, Doi A, Ramirez JM. Activation of alpha-2 noradrenergic receptors is critical for the generation of fictive eupnea and fictive gasping inspiratory activities in mammals in vitro. Eur J Neurosci 2011; 33:2228-37. [PMID: 21615559 DOI: 10.1111/j.1460-9568.2011.07706.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Biogenic amines are not just 'modulators', they are often essential for the execution of behaviors. Here, we explored the role of biogenic amines acting on the pre-Bötzinger complex (pre-BötC), an area located in the ventrolateral medulla which is critical for the generation of different forms of breathing. Isolated in transverse slices from mice, this region continues to spontaneously generate rhythmic activities that resemble normal (eupneic) inspiratory activity in normoxia and gasping in hypoxia. We refer to these as 'fictive eupneic' and 'fictive gasping' activity. When exposed to hypoxia, the pre-BötC transitions from a network state relying on calcium-activated nonspecific cation currents (I(CAN)) and persistent sodium currents (I(Nap)) to one that primarily depends on the I(Nap) current. Here we show that in inspiratory neurons I(Nap)-dependent bursting, blocked by riluzole, but not I(CAN) -dependent bursting, required endogenously released norepinephrine acting on alpha2-noradrenergic receptors (α2-NR). At the network level, fictive eupneic activity persisted while fictive gasping ceased following the blockade of α2-NR. Blockade of α2-NR eliminated fictive gasping even in slice preparations as well as in inspiratory island preparations. Blockade of fictive gasping by α2-NR antagonists was prevented by activation of 5-hydroxytryptamine type 2A receptors (5-HT2A). Our data suggest that gasping depends on the converging aminergic activation of 5-HT2AR and α2-NR acting on riluzole-sensitive mechanisms that have been shown to be crucial for gasping.
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Affiliation(s)
- Jean-Charles Viemari
- Laboratoire Plasticité et Physio-Pathologie de la motricité, CNRS UMR 6196, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
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20
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Liu J, Wei X, Zhao C, Hu S, Duan J, Ju G, Wong-Riley MTT, Liu Y. 5-HT induces enhanced phrenic nerve activity via 5-HT(2A) receptor/PKC mechanism in anesthetized rats. Eur J Pharmacol 2011; 657:67-75. [PMID: 21296069 DOI: 10.1016/j.ejphar.2011.01.048] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Revised: 01/06/2011] [Accepted: 01/20/2011] [Indexed: 10/18/2022]
Abstract
Respiratory behavior expresses diverse forms of plasticity by altering breathing patterns. Failure of respiratory neuroplasticity often leads to malfunctions. Long-term facilitation (LTF), the most frequently studied model induced by episodic hypoxia to produce long-lasting enhancement of phrenic motor output, is thought to be serotonin 2A (5-HT(2A)) receptor-dependent. Previous studies have described 5-HT-induced prompt apnea in intact animals. However, the role of exogenous 5-HT in mediating respiratory neuroplasticity is less attended in vivo study. We hypothesized that an in vivo 5-HT challenge contributes to respiratory neuroplasticity. Here, we found that systemic bolus administration of 5-HT exerted an initial transient inhibition followed by marked facilitation, forming a biphasic pattern of phrenic nerve activity in artificially ventilated, midcervically vagotomized, and anesthetized adult rats. The facilitatory phase corresponded to the enhanced phrenic nerve activity that lasted for at least one hour after drug exposure, characterized as phrenic LTF (pLTF). The 5-HT-induced biphasic pattern and pLTF were 5-HT(2A) receptor-dependent and coupled to protein kinase C (PKC) activation. The initial inhibition of phrenic nerve activity was found to be nodose ganglion-associated, whereas the subsequent facilitation was carotid body-associated, establishing a peripheral inhibitory-facilitatory afferent balance. Immunoreactive expressions of 5-HT/5-HT(2A) receptors and phospho-PKC isoforms/PKC substrate provide morphological evidence of existence of a 5-HT/5-HT(2A) receptor/PKC mechanism in the nodose ganglion and the carotid body. We speculate that 5-HT challenge in vivo may contribute to respiratory neuroplasticity, to yield pLTF or augmented pLTF in animals with reduced or absent peripheral inhibitory inputs.
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Affiliation(s)
- Jinping Liu
- Institute of Neurosciences, The Fourth Military Medical University, Xi'an, PR China.
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21
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Weber MA, Sebire NJ. Post-mortem Investigation of Sudden Unexpected Death in Infancy: Role of Autopsy in Classification of Death. FORENSIC PATHOLOGY REVIEWS 2011. [DOI: 10.1007/978-1-61779-249-6_2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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22
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Liu Q, Wong-Riley MTT. Postnatal changes in tryptophan hydroxylase and serotonin transporter immunoreactivity in multiple brainstem nuclei of the rat: implications for a sensitive period. J Comp Neurol 2010; 518:1082-97. [PMID: 20127812 DOI: 10.1002/cne.22265] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Previously, we found that the brainstem neuronal network in normal rats undergoes abrupt neurochemical, metabolic, and physiological changes around postnatal days (P) 12-13, a critical period when the animal's response to hypoxia is also the weakest. This has special implications for sudden infant death syndrome (SIDS), insofar as seemingly normal infants succumb to SIDS when exposed to respiratory stressors (e.g., hypoxia) during a narrow postnatal window. Because an abnormal serotonergic system has recently been implicated in SIDS, we conducted a large-scale investigation of the 5-HT-synthesizing enzyme tryptophan hydroxylase (TPH) and serotonin transporter (SERT) with semiquantitative immunohistochemistry in multiple brainstem nuclei of normal rats aged P2-21. We found that 1) TPH and SERT immunoreactivity in neurons of raphé magnus, obscurus, and pallidus and SERT in the neuropil of the pre-Bötzinger complex, nucleus ambiguus, and retrotrapezoid nucleus were high at P2-11 but decreased markedly at P12 and plateaued thereafter until P21; 2) SERT labeling in neurons of the lateral paragigantocellular nucleus (LPGi) and parapyramidal region (pPy) was high at P2-9 but fell significantly at P10, followed by a gradual decline until P21; 3) TPH labeling in neurons of the ventrolateral medullary surface was stable except for a significant fall at P12; and 4) TPH and SERT immunoreactivity in a number of other nuclei was relatively stable from P2 to P21. Thus, multiple brainstem nuclei exhibited a significant decline in TPH and SERT immunoreactivity during the critical period, suggesting that such normal development can contribute to a narrow window of vulnerability in postnatal animals.
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Affiliation(s)
- Qiuli Liu
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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23
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Yiallourou SR, Sands SA, Walker AM, Horne RSC. Postnatal development of baroreflex sensitivity in infancy. J Physiol 2010; 588:2193-203. [PMID: 20421281 DOI: 10.1113/jphysiol.2010.187070] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Baroreflex sensitivity (BRS) using spontaneous sequence analysis in the time domain is not fully applicable in infancy, as the time delay for heart period to change (heart period delay, HPD) after an arterial pressure change is unknown. We estimated and compared HPD and BRS in the frequency (BRS(sp), HPD(sp)) and time domains (BRS(seq), HPD(seq)) from systolic blood pressure (SBP) and heart period fluctuations. Continuous SBP, using photoplethysmography, and heart period measurements were performed on 30 term infants at 2-4 weeks, 2-3 months and 5-6 months postnatal age. Cross-spectral analysis between SBP and heart period fluctuations was used to estimate BRS(sp) and HPD(sp). Spontaneous sequence analysis was used to estimate BRS using a fixed beat delay of 1-12 beats (BRS(seq)) or a variable delay identified by a novel method accounting for epoch-epoch variability in HPD (BRS(seqvar)). HPD(sp) averaged 3.4 s (approximately 7 beats); BRS(sp) averaged 11.4 ms mmHg(1). BRS(seq) and BRS(seqvar) were consistently lower than BRS(sp) (P < 0.05), but the three BRS estimates were strongly correlated using a HPD of approximately 5-6 beats. BRS(seqvar) resulted in the average estimate (8.9 ms mmHg(1)) closest to BRS(sp) and overall had the strongest correlation with BRS(sp) (R(2) = 0.61; P < 0.001). All three BRS estimates increased progressively with postnatal age, with BRS(sp) averaging 6.4, 10.5 and 16.0 ms mmHg(1) at 2-4 weeks, 2-3 months and 5-6 months, respectively (P < 0.05). Accounting for the HPD of infancy provides estimates of BRS in the time domain that closely parallel spectral estimates, and provides a novel analytical tool to assess normal development and dysfunction of the baroreflex in infants.
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Affiliation(s)
- Stephanie R Yiallourou
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Victoria, Australia
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24
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Viemari JC, Tryba AK. Bioaminergic neuromodulation of respiratory rhythm in vitro. Respir Physiol Neurobiol 2009; 168:69-75. [PMID: 19538922 DOI: 10.1016/j.resp.2009.03.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 03/25/2009] [Accepted: 03/25/2009] [Indexed: 11/28/2022]
Abstract
Bioamines, such as norepinephrine and serotonin are key neurotransmitters implicated in multiple physiological and pathological brain mechanisms. Evolutionarily, the bioaminergic neuromodulatory system is widely distributed throughout the brain and is among the earliest neurotransmitters to arise within the hindbrain. In both vertebrates and invertebrates, monoamines play a critical role in the control of respiration. In mammals, both norepinephrine and serotonin are involved in the maturation of the respiratory network, as well as in the neuromodulation of intrinsic and synaptic properties, that not only differentially alters the activity of individual respiratory neurons but also the activity of the network during normoxic and hypoxic conditions. Here, we review the basic noradrenergic and serotonergic pathways and their impact on the activity of the pre-Bötzinger Complex inspiratory neurons and network activity.
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Affiliation(s)
- Jean-Charles Viemari
- Laboratoire Plasticité et Physio-Pathologie de la Motricité (P3M), UMR 6196-CNRS, Aix-Marseille Université, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
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25
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Krous HF, Haas E, Hampton CF, Chadwick AE, Stanley C, Langston C. Pulmonary arterial medial smooth muscle thickness in sudden infant death syndrome: an analysis of subsets of 73 cases. Forensic Sci Med Pathol 2009; 5:261-8. [PMID: 19946769 PMCID: PMC2800176 DOI: 10.1007/s12024-009-9116-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/13/2009] [Indexed: 11/26/2022]
Abstract
Previous studies addressing pulmonary artery morphology have compared cases of sudden infant death syndrome (SIDS) to controls but none have compared demographic profiles, exposure to potentially hypoxic risk factors and other pathologic variables in SIDS cases grouped according to pulmonary artery medial smooth muscle thickness. Aims: To compare the relative medial thickness (RMT) in alveolar wall arteries (AW) in SIDS cases with that in age-matched controls and 2. Compare demographic, clinical, and pathologic characteristics among three subsets of SIDS cases based upon alveolar wall (AW) RMT. Retrospective morphometric planimetry of all muscularized arteries in standardized right apical lung sections in 73 SIDS cases divided into three groups based on increasing AW RMT as well as 19 controls age-matched to 19 of the SIDS cases. SIDS and age-matched control cases did not differ with respect to AW RMT or other demographic variables. The SIDS group with the thickest AW RMT had significantly more males and premature birth than the other groups, but the groups did not differ for known clinical risk factors that would potentially expose them to hypoxia. Pathologic variables, including pulmonary inflammation, gastric aspiration, intra-alveolar siderophages, cardiac valve circumferences, and heart and liver weights, were not different between groups. Age was not significantly correlated with RMT of alveolar wall and pre-acinar arteries but was significant at p = .018 for small intra-acinar arteries. The groups were different for RMT of small pre-acinar and intra-acinar arteries, which increased with increasing AW RMT. Statistical differences should not necessarily be equated with clinical importance, however future research incorporating more quantified historical data is recommended.
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Affiliation(s)
- Henry F Krous
- Department of Pathology, Rady Children's Hospital-San Diego, CA 92123, USA.
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26
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Postmortem investigation of sudden unexpected death in infancy: current issues and autopsy protocol. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.mpdhp.2009.08.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Liu Q, Wong-Riley MTT. Postnatal changes in the expressions of serotonin 1A, 1B, and 2A receptors in ten brain stem nuclei of the rat: implication for a sensitive period. Neuroscience 2009; 165:61-78. [PMID: 19800944 DOI: 10.1016/j.neuroscience.2009.09.078] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 09/25/2009] [Accepted: 09/28/2009] [Indexed: 01/08/2023]
Abstract
A critical period in respiratory network development occurs in the rat around postnatal days (P) 12-13, when abrupt neurochemical, metabolic, and physiological changes were evident. As serotonin and its receptors are involved in respiratory modulation, and serotonergic abnormality is implicated in sudden infant death syndrome, we hypothesized that 5-HT receptors are significantly downregulated during the critical period. This was documented recently for 5-HT(2A)R in several respiratory nuclei. The present study represents a comprehensive analysis of postnatal development of 5-HT(1A)R and 5-HT(1B)R in 10 brain stem nuclei and 5-HT(2A)R in six nuclei not previously examined. Optical densitometric analysis of immunohistochemically-reacted neurons from P2 to P21 indicated four developmental patterns of expression: (1) Pattern I: a high level of expression at P2-P11, an abrupt and significant reduction at P12, followed by a plateau until P21 (5-HT(1A)R and 5-HT(1B)R in raphé magnus [RM], raphé obscurus [ROb], raphé pallidus [RP], pre-Bötzinger complex [PBC], nucleus ambiguus [Amb], and hypoglossal nucleus [XII; 5-HT(1A)R only]). (2) Pattern II: a high level at P2-P9, a gradual decline from P9 to P12, followed by a plateau until P21 (5-HT(1A)R and 5-HT(1B)R in the retrotrapezoid nucleus (RTN)/parafacial respiratory group (pFRG)). (3) Pattern III: a high level at P2-P11, followed by a gradual decline until P21 (5-HT(1A)R in the ventrolateral subnucleus of solitary tract nucleus [NTS(VL)] and the non-respiratory cuneate nucleus [CN]). (4) Pattern IV: a relatively constant level maintained from P2 to P21 (5-HT(1A)R in the commissural subnucleus of solitary tract nucleus (NTS(COM)); 5-HT(1B)R in XII, NTS(VL), NTS(COM), and CN; and 5-HT(2A)R in RM, ROb, RP, RTN/pFRG, NTS(VL), and NTS(COM)). Thus, a significant reduction in the expression of 5-HT(1A)R, 5-HT(1B)R, and 5-HT(2A)R in multiple respiratory-related nuclei at P12 is consistent with reduced serotonergic transmission during the critical period, thereby rendering the animals less able to respond adequately to ventilatory distress.
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Affiliation(s)
- Q Liu
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, 53226, USA
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28
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Interleukin-6 and the serotonergic system of the medulla oblongata in the sudden infant death syndrome. Acta Neuropathol 2009; 118:519-30. [PMID: 19396608 DOI: 10.1007/s00401-009-0535-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 04/05/2009] [Accepted: 04/06/2009] [Indexed: 10/20/2022]
Abstract
Mild infection may trigger sudden death in the vulnerable infant by cytokine interactions with a compromised medullary serotonergic (5-HT) system, leading to disrupted cardiorespiratory regulation and sleep-related sudden death. The cytokine interleukin (IL)-6 is elevated in the cerebrospinal fluid in SIDS. We tested the hypothesis that the expression of IL-6 receptors (IL-6R) and/or gp130 (involved in IL-6R signaling) is altered in the medullary 5-HT system in SIDS. Immunohistochemistry of IL-6R and gp130 was performed on medullae from 25 SIDS infants, 20 infectious deaths, and 14 controls using a semi-quantitative grading system. In the SIDS cases, mean IL-6R intensity grade in the arcuate nucleus (major component of medullary 5-HT system) was significantly higher than in the control group (2.00 +/- 0.07 vs. 1.77 +/- 0.08, P = 0.04), with no other differences in IL-6R or gp130 expression at any other site. Arcuate 5-HT neurons expressed IL-6R, indicating a site of IL-6/5-HT interaction. In SIDS, IL-6R expression is abnormal in the arcuate nucleus, the putative human homolog of rodent ventral medullary chemosensitivity sites involving 5-HT. Aberrant interactions between IL-6 and the arcuate nucleus may contribute to impaired responses to hypercapnia generated by infection (hyper-metabolism) combined with rebreathing.
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29
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Duncan JR, Garland M, Myers MM, Fifer WP, Yang M, Kinney HC, Stark RI. Prenatal nicotine-exposure alters fetal autonomic activity and medullary neurotransmitter receptors: implications for sudden infant death syndrome. J Appl Physiol (1985) 2009; 107:1579-90. [PMID: 19729586 DOI: 10.1152/japplphysiol.91629.2008] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During pregnancy, exposure to nicotine and other compounds in cigarette smoke increases the risk of the sudden infant death syndrome (SIDS) two- to fivefold. Serotonergic (5-HT) abnormalities are found, in infants who die of SIDS, in regions of the medulla oblongata known to modulate cardiorespiratory function. Using a baboon model, we tested the hypothesis that prenatal exposure to nicotine alters 5-HT receptor and/or transporter binding in the fetal medullary 5-HT system in association with cardiorespiratory dysfunction. At 87 (mean) days gestation (dg), mothers were continuously infused with saline (n = 5) or nicotine (n = 5) at 0.5 mg/h. Fetuses were surgically instrumented at 129 dg for cardiorespiratory monitoring. Cesarean section delivery and retrieval of fetal medulla were performed at 161 (mean) dg for autoradiographic analyses of nicotinic and 5-HT receptor and transporter binding. In nicotine-exposed fetuses, high-frequency heart rate variability was increased 55%, possibly reflecting increases in the parasympathetic control of heart rate. This effect was more pronounced with greater levels of fetal breathing and age. These changes in heart rate variability were associated with increased 5-HT(1A) receptor binding in the raphé obscurus (P = 0.04) and increased nicotinic receptor binding in the raphé obscurus and vagal complex (P < 0.05) in the nicotine-exposed animals compared with controls (n = 6). The shift in autonomic balance in the fetal primate toward parasympathetic predominance with chronic exposure to nicotine may be related, in part, to abnormal 5-HT-nicotine alterations in the raphé obscurus. Thus increased risk for SIDS due to maternal smoking may be partly related to the effects of nicotine on 5-HT and/or nicotinic receptors.
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Affiliation(s)
- Jhodie R Duncan
- Dept. of Pathology, Enders 1112.1, Children's Hospital Boston, 300 Longwood Ave., Boston, MA 02115, USA
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Kinney HC. Brainstem mechanisms underlying the sudden infant death syndrome: evidence from human pathologic studies. Dev Psychobiol 2009; 51:223-33. [PMID: 19235901 DOI: 10.1002/dev.20367] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The brainstem hypothesis is one of the leading hypotheses concerning the sudden infant death syndrome (SIDS). It states that SIDS, or an important subset of SIDS, is due to abnormal brainstem mechanisms in the control of respiration, chemosensitivity, autonomic regulation, and/or arousal which impairs the infant's response to life-threatening, but often occurring, stressors during sleep (e.g., hypoxia, hypercarbia, asphyxia, hyperthermia) and leads to sudden death in a vulnerable developmental period. In this review, we summarize neuropathologic evidence from SIDS cases that support this hypothesis, beginning with the seminal report of subtle brainstem gliosis three decades ago. We focus upon recent neurochemical studies in our laboratory concerning the neurotransmitter serotonin (5-HT) and its key role in mediating protective responses to homeostatic stressors via medullary circuits. The possible fetal origin of brainstem defects in SIDS is reviewed, including evidence for adverse effects of prenatal exposure to maternal cigarette smoking and alcohol upon the postnatal development of human brainstem 5-HT pathways.
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Affiliation(s)
- Hannah C Kinney
- Department of Pathology, Children's Hospital Boston and Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
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Krous HF, Ferandos C, Masoumi H, Arnold J, Haas EA, Stanley C, Grossfeld PD. Myocardial inflammation, cellular death, and viral detection in sudden infant death caused by SIDS, suffocation, or myocarditis. Pediatr Res 2009; 66:17-21. [PMID: 19287341 DOI: 10.1203/pdr.0b013e3181a290a7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The significance of minor myocardial inflammatory infiltrates and viral detection in SIDS is controversial. We retrospectively compared the demographic profiles, myocardial inflammation, cardiomyocyte necrosis, and myocardial virus detection in infants who died of SIDS in a safe sleep environment, accidental suffocation, or myocarditis. Formalin-fixed, paraffin-embedded myocardial sections were semiquantitatively assessed for CD3 lymphocytes and CD68 macrophages using immunohistochemistry and for cardiomyocyte cell death in H&E-stained sections. Enteroviruses and adenoviruses were searched for using PCR technology. The means of lymphocytes, macrophages, and necrotic cardiomyocytes were not statistically different in SIDS and suffocation cases. Enterovirus, not otherwise specified, was detected in one suffocation case and was the only virus detected in the three groups. Very mild myocardial lymphocyte and macrophage infiltration and scattered necrotic cardiomyocytes in SIDS are not pathologic, but may occur after the developing heart is exposed to environmental pathogens, including viruses.
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Affiliation(s)
- Henry F Krous
- Department of Pathology, University of California-San Diego, La Jolla, CA 92037, USA
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Hoogstraate SR, Lequin MH, Huysman MA, Ahmed S, Govaert PP. Apnoea in relation to neonatal temporal lobe haemorrhage. Eur J Paediatr Neurol 2009; 13:356-61. [PMID: 18757218 DOI: 10.1016/j.ejpn.2008.07.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 07/01/2008] [Accepted: 07/09/2008] [Indexed: 10/21/2022]
Abstract
BACKGROUND Six term newborns presented with apnoea and temporal lobe haemorrhage. AIM In this observational study, we described involvement of the limbic system in apnoeic term newborns with temporal lobe injury. METHODS Six term newborns presented to the neonatal care unit with apnoea within the first 2 days of life. Ultrasound (US) and MRI of the brain were obtained in the first week of life. RESULTS Apnoea was related to temporal lobe haemorrhage in all. During apnoeic periods four had focal epileptic activity on EEG. All lesions were detected first with US. On MRI, haemorrhages were located in the parenchyma, the subdural and/or subarachnoid space. Three haemorrhages were surrounded by infarction in the temporal lobe. In three infants hippocampus and mesial temporal cortex were affected. In two basal temporal cortex only was involved. Vascular anomalies were excluded by MRA, serial MRI or serial US with Doppler imaging. CONCLUSION Term infants with seizure associated apnoea may present with haemorrhage and/or infarction to hippocampus, mesial and basal temporal cortex. This study supports the existence and possible disruption of descending influences from the temporal cortex and/or amygdala on brainstem breathing centres in the term newborn.
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Affiliation(s)
- Sander R Hoogstraate
- Department of Radiology, Albert Schweitzer Ziekenhuis, loc Dordwijk, Dordrecht, The Netherlands.
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Abstract
Neuroscientists have long sought to understand how circuits in the nervous system are organized to generate the precise neural outputs that underlie particular behaviors. Recent studies deepened our understanding of the mechanisms responsible for the generation of the rhythmic output for breathing. Here, the author focuses on issues that are pertinent for the respiratory network and considers its organization and how it derives the functional output. The author discusses pacemaker and network mechanisms of rhythm generation, which are now combined into a novel concept of emergent network activity due to coherent excitation of pacemaker groups. He discusses subcellular basis of this hypothesis and possible mechanisms of synchronization within respiratory network. These new findings in respiratory neuroscience are further applied to explain modifications in breathing during hypoxia and possible origins of respiratory disorders that may be acquired during neural development and aging.
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Affiliation(s)
- Sergej Mironov
- DFG-Center of Molecular Physiology of the Brain, Department of Neuro- and Sensory Physiology, Georg-August University, Göttingen, Germany.
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Campos M, Bravo E, Eugenín J. Respiratory dysfunctions induced by prenatal nicotine exposure. Clin Exp Pharmacol Physiol 2009; 36:1205-17. [PMID: 19473189 DOI: 10.1111/j.1440-1681.2009.05214.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. Maternal tobacco smoking is the principal risk factor associated with sudden infant death syndrome (SIDS), a leading cause of death of infants under 1 year of age. Victims of SIDS show a higher incidence of respiratory control abnormalities, including central apnoeas, delayed arousal responses and diminished ventilatory chemoreflexes. 2. Nicotine is likely the link between maternal tobacco smoking and SIDS. Prenatal nicotine exposure can alter the breathing pattern and can reduce hypoxia- and hypercarbia-induced ventilatory chemoreflexes. In vitro approaches have revealed that prenatal nicotine exposure impairs central chemosensitivity, switching the cholinergic contribution from a muscarinic to a nicotinic receptor-based drive. In addition, serotonergic, noradrenergic, GABAergic, glycinergic and glutamatergic, among others, are affected by prenatal nicotine. 3. Here we propose that prenatal nicotine affects the respiratory network through two main processes: (i) reorganization of neurotransmitter systems; and (ii) remodelling of neural circuits. These changes make breathing more vulnerable to fail in early postnatal life, which could be related to the pathogenesis of SIDS.
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Affiliation(s)
- Marlys Campos
- Laboratory of Neural Systems, Department of Biology, Universidad de Santiago, USACH, Santiago, Chile
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Doi A, Ramirez JM. Neuromodulation and the orchestration of the respiratory rhythm. Respir Physiol Neurobiol 2009; 164:96-104. [PMID: 18602029 DOI: 10.1016/j.resp.2008.06.007] [Citation(s) in RCA: 172] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Revised: 06/05/2008] [Accepted: 06/06/2008] [Indexed: 10/22/2022]
Abstract
The respiratory system is continuously modulated by numerous aminergic and peptidergic substances that act at all levels of integration: from the sensory level to the level of central networks and motor nuclei. The same neuronal networks receive inputs from multiple modulators released locally as well as from distal nuclei. All parameters of respiratory control are controlled by multiple neuromodulators. By partly converging onto similar G-proteins and second messenger systems, acetylcholine, norepinephrine, histamine, serotonin (5-HT), dopamine, ATP, substance P, cholecystokinin (CCK) can increase frequency, regularity and amplitude of respiratory activity. Yet, the same modulator can also exert differential effects on respiratory activity by acting on different receptors partly in the same neurons. In the pre-Bötzinger complex (pre-BötC) modulators can differentially modulate frequency and amplitude in different types of pacemaker neurons. Similarly motoneurons located in different motor nuclei receive differential amplitude modulation from different modulators. Thus, modulators are capable of orchestrating and modulating different parameters of respiratory activity by differentially targeting different cellular targets. A disturbance in modulatory control may lead to Sudden Infant Death Syndrome (SIDS) and erratic breathing.
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Affiliation(s)
- Atsushi Doi
- Department of Organismal Biology and Anatomy, The University of Chicago, 1027 East 57th Street, Chicago, IL 60637, USA.
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Serotoninergic receptor 1A in the sudden infant death syndrome brainstem medulla and associations with clinical risk factors. Acta Neuropathol 2009; 117:257-65. [PMID: 19052756 DOI: 10.1007/s00401-008-0468-x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Revised: 11/04/2008] [Accepted: 11/26/2008] [Indexed: 10/21/2022]
Abstract
The immunoreactivity of the serotoninergic receptor subtype 1A (5HT(1A)R) was quantitatively analyzed in the human infant brainstem medulla (caudal and rostral levels). We hypothesized that immunoreactivity of 5HT(1A)R would be reduced in infants diagnosed with sudden infant death syndrome (SIDS). In particular that those infants with known clinical risk factors (including cigarette smoke exposure, bed sharing and sleep position) would have greater changes than those without clinical risks. Comparing SIDS (n = 67) to infants who died suddenly with another diagnosis (non-SIDS, n = 25), we found decreased 5HT(1A)R immunoreactivity in the majority of the nuclei studied at the rostral medulla level including dorsal motor nucleus of the vagus (DMNV), nucleus of the solitary tract, vestibular, and inferior olivary nucleus (ION). There was a significant relationship with all risk factors for 5HT(1A)R, especially for DMNV, suggesting that 5HT(1A)Rs are highly vulnerable to various insults within the SIDS DMNV. This study not only provides further evidence of abnormalities within the brainstem serotoninergic system of SIDS infants, but also shows that these changes may be associated with exposure to clinical risk factors.
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Leptomeningeal neurons are a common finding in infants and are increased in sudden infant death syndrome. Acta Neuropathol 2009; 117:275-82. [PMID: 19205709 DOI: 10.1007/s00401-009-0489-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 01/11/2009] [Accepted: 01/22/2009] [Indexed: 10/21/2022]
Abstract
Developmental abnormalities of the brain, in particular, the brainstem potentially affecting centers for breathing, circulation and sleep regulation, are thought to be involved in the etiology of sudden infant death syndrome (SIDS). In order to investigate whether leptomeningeal neurons could serve as morphological indicators for a developmental failure or retardation in cerebral maturation, we evaluated the density of isolated leptomeningeal neurons (without associated glia) in 15 brain regions of 24 SIDS and 8 control cases, representing part of the German Study on sudden infant death. Leptomeningeal neurons were encountered in 79% of SIDS and 68% of control cases. More leptomeningeal neurons in SIDS versus control cases were found in lower pons (p = 0.002), upper pons (p = 0.016), cerebellar hemispheres (p = 0.012), lower medulla oblongata (p = 0.039), and temporal lobe (p = 0.041). Summarizing the data according to gross anatomical region of origin (i.e., brainstem, cerebellum or cerebrum), higher numbers of leptomeningeal neurons in SIDS cases were only found in the brainstem (p = 0.006 vs. 0.13 and 0.19, respectively). Our data show that single leptomeningeal neurons are present in most normal infantile brains. The age-dependent increase of leptomeningeal neurons among SIDS cases may either (a) represent a delayed maturation or retardation, i.e., a later or slower reduction of neurons or a delayed peak in occurrence (shift toward an older age), or (b) may be interpreted as a generally increased occurrence of leptomeningeal neurons among SIDS cases as a result of a diffuse developmental abnormality during central nervous system maturation.
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Erickson JT, Sposato BC. Autoresuscitation responses to hypoxia-induced apnea are delayed in newborn 5-HT-deficient Pet-1 homozygous mice. J Appl Physiol (1985) 2009; 106:1785-92. [PMID: 19213929 DOI: 10.1152/japplphysiol.90729.2008] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Autoresuscitation is a critical survival-promoting mechanism in mammals that allows recovery from primary apnea via hypoxia-induced gasping. Here we show, using head-out plethysmography, that gasping behavior is altered during autoresuscitation, and the autoresuscitation response is delayed, in neonatal 5-hydroxytryptamine (5-HT) neuron-deficient Pet-1 homozygous (Pet-1(-/-)) mice. When exposed to 97% N(2)-3% CO(2) on postnatal day 4.5, unanesthetized Pet-1(-/-) mice required over four times longer than age-matched wild-type controls to initiate gasping following primary apnea. When oxygen was made available before the first gasp, allowing autoresuscitation to occur, gasping frequency was decreased and the duration of the gasping period was extended in the Pet-1 mutants compared with wild type, resulting in a nearly threefold increase in the time needed for successful autoresuscitation. However, when the exposure to anoxia was unrelenting, gasping frequency, the form of the gasps, the total number of gasps produced, the duration of the gasping period, and time to last gasp were comparable to controls. Plethysmographic testing of the same mutants on postnatal day 9.5 revealed that their autoresuscitation responses, although improved compared with day 4.5, remained significantly longer than in wild-type controls. Our data indicate that despite a severe deficiency of central 5-HT neurons, Pet-1(-/-) neonatal mice are capable of gasping, but their gasping pattern is altered during autoresuscitation, leading to a prolongation of the time required to recover from hypoxia-induced apnea.
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Duncan JR, Paterson DS, Kinney HC. The development of nicotinic receptors in the human medulla oblongata: inter-relationship with the serotonergic system. Auton Neurosci 2008; 144:61-75. [PMID: 18986852 DOI: 10.1016/j.autneu.2008.09.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Revised: 09/17/2008] [Accepted: 09/23/2008] [Indexed: 02/05/2023]
Abstract
Maternal cigarette smoking during pregnancy adversely affects fetal development and increases the risk for the sudden infant death syndrome (SIDS). In SIDS we have reported abnormalities in the medullary serotonergic (5-HT) system, which is vital for homeostatic control. In this study we analyzed the inter-relationship between nicotinic receptors (nAChRs), to which nicotine in cigarette smoke bind, and the medullary 5-HT system in the human fetus and infant as a step towards determining the mechanisms whereby smoking increases SIDS risk in infants with 5-HT defects. Immunohistochemistry for the alpha4 nAChR subunit and 5-HT neurons was applied in fetal and infant medullae (15-92 postconceptional weeks, n=9). The distribution of different nAChRs was determined from 39-82 postconceptional weeks (n=5) using tissue autoradiography for 3H-nicotine, 3H-epibatidine, 3H-cytisine, and 125I-bungarotoxin; the findings were compared to laboratory 5-HT1A and 5-HT transporter binding data, and 5-HT neuronal density. Alpha4 immunoreactivity was ubiquitously expressed in medullary nuclei related to homeostatic functions from 15 weeks on, including rhombic lip germinal cells. At all ages, alpha4 co-localized with 5-HT neurons, indicating a potential site of interaction whereby exogenous nicotine may adversely affect 5-HT neuronal development and function. Binding for heteromeric nAChRs was highest in the inferior olive, and for homomeric nAChRs, in the vagal complex. In the paragigantocellularis lateralis, 5-HT1A receptor binding simultaneously increased as alpha7 binding decreased across infancy. This study indicates parallel dynamic and complex changes in the medullary nicotinic and 5-HT systems throughout early life, i.e., the period of risk for SIDS.
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Affiliation(s)
- Jhodie R Duncan
- Department of Pathology, Children's Hospital Boston and Harvard Medical School, Boston, Massachusetts 02115, USA.
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Larkin EK, Patel SR, Elston RC, Gray-McGuire C, Zhu X, Redline S. Using linkage analysis to identify quantitative trait loci for sleep apnea in relationship to body mass index. Ann Hum Genet 2008; 72:762-73. [PMID: 18754839 DOI: 10.1111/j.1469-1809.2008.00472.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
To understand the genetics of sleep apnea, we evaluated the relationship between the apnea hypopnea index (AHI) and body mass index (BMI) through linkage analysis to identify genetic loci that may influence AHI and BMI jointly and AHI independent of BMI. Haseman-Elston sibling regression was conducted on AHI, AHI adjusted for BMI and BMI in African-American and European-American pedigrees. A comparison of the magnitude of linkage peaks was used to assess the relationship between AHI and BMI. In EAs, the strongest evidence for linkage to AHI was on 6q23-25 and 10q24-q25, both decreasing after BMI adjustment, suggesting loci with pleiotropic effects. Also, a promising area of linkage to AHI but not BMI was observed on 6p11-q11 near the orexin-2 receptor, suggesting BMI independent pathways. In AAs the strongest evidence of linkage for AHI after adjusting for BMI was on chromosome 8p21.3 with linkage increasing after BMI adjustment and on 8q24.1 with linkage decreasing after BMI adjustment. Novel linkage peaks were also observed in AAs to both BMI and AHI on chromosome 13 near the serotonin-2a receptor. These analyses suggest genetic loci for sleep apnea that operate both independently of BMI and through BMI-related pathways.
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Affiliation(s)
- E K Larkin
- Center for Clinical Investigation, Case Western Reserve University, School of Medicine, Cleveland, OH 44106-6083, USA.
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Hodges MR, Richerson GB. Interaction between defects in ventilatory and thermoregulatory control in mice lacking 5-HT neurons. Respir Physiol Neurobiol 2008; 164:350-7. [PMID: 18775520 DOI: 10.1016/j.resp.2008.08.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 08/08/2008] [Accepted: 08/11/2008] [Indexed: 11/28/2022]
Abstract
We have previously shown that mice with near-complete absence of 5-HT neurons (Lmx1bf/f/p) display a blunted hypercapnic ventilatory response (HCVR) and impaired cold-induced thermogenesis, but have normal baseline ventilation (), core body temperature (TCore) and hypoxic ventilatory responses (HVR) at warm ambient temperatures (TAmb; 30 degrees C). These results suggest that 5-HT neurons are an important site for integration of ventilatory, metabolic and temperature control. To better define this integrative role, we now determine how a moderate cold stress (TAmb of 25 degrees C) influences ventilatory control in adult Lmx1bf/f/p mice. During whole animal plethysmographic recordings at 25 degreesC, baseline , metabolic rate , and TCore of Lmx1bf/f/p mice were reduced (P < 0.001) compared to wild type (WT) mice. Additionally, the HCVR was reduced in Lmx1bf/f/p mice during normoxic (-33.1%) and hyperoxic (-40.9%) hypercapnia. However, in Lmx1bf/f/p mice was equal to that in WT mice while breathing 10% CO2, indicating that non-5-HT neurons may play a dominant role during extreme hypercapnia. Additionally, ventilation was decreased during hypoxia in Lmx1bf/f/p mice compared to WT mice at 25 degrees C due to decreased TCore. These data suggest that a moderate cold stress in Lmx1bf/f/p mice leads to further dysfunction in ventilatory control resulting from failure to adequately maintain TCore. We conclude that 5-HT neurons contribute to the hypercapnic ventilatory response under physiologic, more than during extreme levels of CO2, and that mild cold stress further compromises ventilatory control in Lmx1bf/f/p mice as a result of defective thermogenesis.
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Affiliation(s)
- Matthew R Hodges
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, United States.
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Apolipoprotein E e4 and its prevalence in early childhood death due to sudden infant death syndrome or to recognised causes. Early Hum Dev 2008; 84:549-54. [PMID: 18280677 DOI: 10.1016/j.earlhumdev.2008.01.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Accepted: 01/08/2008] [Indexed: 11/23/2022]
Abstract
BACKGROUND Specific genetic polymorphisms have been shown to be more common in unexplained infant death. The APOE genotype exhibits opposite effects at the extremes of age with protective effects of e4 on perinatal mortality but detrimental effects as age progresses. OBJECTIVE To determine whether the APOE e4 allele is associated with early childhood (1 week-2 years) unexplained death ('sudden infant death syndrome', SIDS) or with recognised causes (non-SIDS) and to compare these cohorts with published perinatal and adult data. METHODS DNA was extracted from spleen tissue of children dying in South East Scotland between 1990 and 2002. APOE alleles (e2, e3, e4) were determined using PCR. Comparisons of allele frequencies between groups were made. RESULTS There were 167 SIDS cases and 117 non-SIDS cases. Allele distributions of SIDS cases were similar to healthy newborns. Allele distributions of non-SIDS cases were more similar to adults than to healthy newborns. The percentage of children with at least one e4 allele was significantly lower in non-SIDS compared to SIDS (p = 0.016). Non-SIDS cases had a higher frequency of e3 compared to SIDS cases (p = 0.01) and to healthy newborns (0.005). CONCLUSIONS Children dying from identified causes have different APOE allele distributions from SIDS cases, but are similar to adults. Children dying from SIDS have an allele distribution comparable to healthy newborns. The prevalence of e4 in SIDS is not of an order to contribute significantly to the age-related decline in e4.
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Abstract
AIM To investigate polymorphisms in the serotonin transporter (5-HTT) gene in cases of sudden infant death syndrome (SIDS) and controls, and further to elucidate a possible relationship between 5-HTT genotypes and external risk factors for SIDS. METHOD The subjects investigated consist of 163 SIDS cases and 243 controls. Polymorphisms in both the promoter and intron 2 of the 5-HTT gene were investigated, and the genotypes were determined using polymerase chain reaction (PCR) and gel electrophoresis. RESULTS In the promoter, there was a tendency for the L allele and L/L genotype to be found more often in the SIDS cases than in the controls (p=0.05 and p=0.07, respectively). Regarding the intron 2 polymorphism, there were no differences between the groups, and the SIDS cases were not found to have a higher frequency of either the L/L-12/12 genotype or the L-12 haplotype than the controls. When investigating possible correlations between genotype and risk factors for SIDS, there was a tendency towards different distribution of the promoter genotypes in cases found dead prone compared to cases found dead in other sleeping positions (p=0.06). CONCLUSION Polymorphisms in the promoter of the 5-HTT gene may be of importance with regard to SIDS.
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Affiliation(s)
- Siri Hauge Opdal
- Institute of Forensic Medicine, University of Oslo, Pathology Clinic, Rikshospitalet University Hospital, Oslo, Norway.
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Liu Q, Wong-Riley MTT. Postnatal changes in the expression of serotonin 2A receptors in various brain stem nuclei of the rat. J Appl Physiol (1985) 2008; 104:1801-8. [PMID: 18420721 DOI: 10.1152/japplphysiol.00057.2008] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Previously, we reported a critical period [around postnatal day (P) 12-13 in the rat] in respiratory network development when distinct neurochemical, metabolic, and physiological changes occur. Since serotonin 2A (5-HT(2A)) receptors play an important role in respiratory modulation, we hypothesized that they may undergo developmental adjustments during the critical period. Semi-quantitative immunohistochemical analyses were conducted in labeled neurons in a number of brain stem nuclei with or without known respiratory functions from P2 to P21 in rats. Our data indicate that the expressions of 5-HT(2A) receptors in neurons of the pre-Bötzinger complex, the nucleus ambiguus, and the hypoglossal nucleus were maintained within a relatively narrow range between P2 and P21, with a dip at P3-P4 and a significant reduction only at P12. This change was not observed in the nonrespiratory cuneate nucleus. These results suggest that reduced expressions of 5-HT(2A) receptors at P12 contributes to neurochemical imbalance within brain stem respiratory nuclei at that time and may be involved in decreased hypoxic ventilatory response at this critical period of development.
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Affiliation(s)
- Qiuli Liu
- Dept. of Cell Biology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Brown JW, Sirlin EA, Benoit AM, Hoffman JM, Darnall RA. Activation of 5-HT1A receptors in medullary raphé disrupts sleep and decreases shivering during cooling in the conscious piglet. Am J Physiol Regul Integr Comp Physiol 2008; 294:R884-94. [DOI: 10.1152/ajpregu.00655.2007] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Activation of 5-HT1A receptors in the medullary raphé decreases sympathetically mediated brown adipose tissue (BAT) thermogenesis and peripheral vasoconstriction when previously activated with leptin, LPS, prostaglandins, or cooling. It is not known whether shivering is also modulated by medullary raphé 5-HT1A receptors. We previously showed in conscious piglets that activation of 5-HT1A receptors with (±)-8-hydroxy-2-(dipropylamino)-tetralin (8-OH-DPAT) in the paragigantocellularis lateralis (PGCL), a medullary region lateral to the raphé that contains substantial numbers of 5-HT neurons, eliminates rapid eye movement (REM) sleep and decreases shivering in a cold environment, but does not attenuate peripheral vasoconstriction. Hoffman JM, Brown JW, Sirlin EA, Benoit AM, Gill WH, Harris MB, Darnall RA. Am J Physiol Regul Integr Comp Physiol 293: R518–R527, 2007. We hypothesized that, during cooling, activation of 5-HT1A receptors in the medullary raphé would also eliminate REM sleep and, in contrast to activation of 5-HT1A receptors in the PGCL, would attenuate both shivering and peripheral vasoconstriction. In a continuously cool environment, dialysis of 8-OH-DPAT into the medullary raphé resulted in alternating brief periods of non-REM sleep and wakefulness and eliminated REM sleep, as observed when 8-OH-DPAT is dialyzed into the PGCL. Moreover, both shivering and peripheral vasoconstriction were significantly attenuated after 8-OH-DPAT dialysis into the medullary raphé. The effects of 8-OH-DPAT were prevented after dialysis of the selective 5-HT1A receptor antagonist WAY-100635. We conclude that, during cooling, exogenous activation of 5-HT1A receptors in the medullary raphé decreases both shivering and peripheral vasoconstriction. Our data are consistent with the hypothesis that neurons expressing 5-HT1A receptors in the medullary raphé facilitate spinal motor circuits involved in shivering, as well as sympathetic stimulation of other thermoregulatory effector mechanisms.
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Wiemann M, Frede S, Tschentscher F, Kiwull-Schöne H, Kiwull P, Bingmann D, Brinkmann B, Bajanowski T. NHE3 in the Human Brainstem: Implication for the Pathogenesis of the Sudden Infant Death Syndrome (SIDS)? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 605:508-13. [DOI: 10.1007/978-0-387-73693-8_89] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
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Malloy MH. Size for gestational age at birth: impact on risk for sudden infant death and other causes of death, USA 2002. Arch Dis Child Fetal Neonatal Ed 2007; 92:F473-8. [PMID: 17314115 PMCID: PMC2675379 DOI: 10.1136/adc.2006.107094] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Small for gestational age (SGA) infants have been reported to be at higher risk for sudden infant death syndrome (SIDS). OBJECTIVE To compare the risk of SIDS among SGA and large for gestational age (LGA) infants with that of death from other causes of sudden unexpected deaths in infancy (SUDI) and the residual "other" causes of infant death. METHODS The 2002 US period infant birth and death certificate linked file was used to identify infant deaths classified as SIDS (ICD-10 code R95), SUDI (ICD-10 codes R00-Y84 excluding R95) or all other residual codes. The 2002 race and sex-specific birth cohorts were used to generate the 10th and 90th percentiles of birth weight for each gestational age week from 24 to 42 weeks' gestation. Demographic variables previously identified as associated with SIDS were used in multiple logistic regression equations to determine the risk for death among SGA and LGA infants (birth weight <10th percentile and >90th percentile, respectively) independent of other potentially confounding variables. RESULTS Complete data on 1956 SIDS deaths, 2012 SUDI, and 11 592 other deaths were available. The adjusted OR for SIDS, SUDI and "other" causes for SGA infants was 1.65 (95% CI 1.47 to 1.85), 1.78 (1.59 to 2.00) and 4.68 (4.49 to 4.88), respectively. The adjusted OR for LGA infants was reduced for SIDS (0.73 (0.60 to 0.89)), SUDI (0.81 (0.68 to 0.98)) and "other" (0.42 (0.38 to 0.46)). CONCLUSION Although SGA infants seem to be at slightly increased risk for SIDS or SUDI their risk for "other" residual causes is about 2.5 times higher. LGA infants seem to be at reduced risk of mortality for all causes. The mechanisms by which restricted intrauterine growth increases risk of mortality and excessive intrauterine growth offers protective effects are uncertain.
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Affiliation(s)
- Michael H Malloy
- Department of Pediatrics, University of Texas Medical Branch, 301 University Blvd, Galveston, Texas, USA.
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Kahlert C, Rudin C, Kind C. Sudden infant death syndrome in infants born to HIV-infected and opiate-using mothers. Arch Dis Child 2007; 92:1005-8. [PMID: 17556395 PMCID: PMC2083611 DOI: 10.1136/adc.2007.117192] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVE This study was undertaken to determine the role of opiate use during pregnancy as a predisposing factor for sudden infant death syndrome (SIDS) in infants born to HIV-infected mothers. METHODS In order to identify all infant deaths and their cause and association with maternal opiate use, the data of a nationwide prospective cohort study of HIV-infected mothers and their children were extracted and analysed for a 13-year period. RESULTS 24 (5.1%) infant deaths were observed out of 466 infants followed up until death or at least 12 months of life. 3 (0.6%) of them were due to non-accidental trauma and were not associated with maternal opiate use. 7 (1.5%) died due to SIDS, which was confirmed by autopsy. All SIDS cases occurred in infants born to mothers reporting use of opiates during pregnancy (n = 124). The relative risk of SIDS compared to the general population was 18 (95% CI 9 to 38) for all infants of HIV-infected mothers, and 69 (95% CI 33 to 141) for those with intrauterine opiate exposure (p<0.001). CONCLUSIONS Compared to the Swiss general population, the risk for SIDS in this cohort of infants born to HIV-infected mothers was greatly increased, but only for mothers reporting opiate use during pregnancy. This effect appeared not to be mediated by prematurity, low birth weight, perinatal HIV infection or antiretroviral drug exposure.
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Cutz E, Yeger H, Pan J. Pulmonary neuroendocrine cell system in pediatric lung disease-recent advances. Pediatr Dev Pathol 2007; 10:419-35. [PMID: 18001162 DOI: 10.2350/07-04-0267.1] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Accepted: 09/04/2007] [Indexed: 11/20/2022]
Abstract
The airway epithelium of human and animal lungs contains highly specialized pulmonary neuroendocrine cells (PNEC), distributed as solitary cells and as innervated clusters, neuroepithelial bodies (NEB). The designation "PNEC system" stems from the expression of both neural and endocrine cell phenotypes, including the synthesis and release of amine (serotonin, 5-HT) and a variety of neuropeptides (that is, bombesin). The role and function of PNEC in the lung have remained a subject of speculation for many years. During the last decade, studies using modern techniques of cellular and molecular biology revealed a complex functional role for PNEC, beginning during the early stages of lung development as modulators of fetal lung growth and differentiation and at the time of birth as airway O2 sensors involved in neonatal adaptation. Postnatally and beyond, PNEC/NEB are providers of a lung stem cell niche that is important in airway epithelial regeneration and lung carcinogenesis. The focus of this review is to present and discuss recent findings pertaining to the responses of PNEC to intrauterine environmental stimuli, ontogeny and molecular regulation of PNEC differentiation, innervation of NEB, and their role as airway chemoreceptors, including mechanisms of O2 sensing and chemotransmission of hypoxia stimulus. Abnormalities of PNEC/NEB have been reported in a variety of pediatric pulmonary disorders but the clinical significance or the mechanisms involved are unknown. The discussion on the possible role of PNEC/NEB in the pathogenesis and pathobiology of pediatric lung diseases includes congenital lung disorders, bronchopulmonary dysplasia, disorders of respiratory control, neuroendocrine hyperplasia of infancy, cystic fibrosis, bronchial asthma, and pulmonary hypertension.
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Affiliation(s)
- Ernest Cutz
- Department of Pediatric Laboratory Medicine, The Hospital for Sick Children, University of Toronto, Toronto,ON, Canada.
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Krous HF, Chadwick AE, Haas E, Masoumi H, Stanley C. Sudden infant death while awake. Forensic Sci Med Pathol 2007; 4:40-6. [PMID: 19291468 DOI: 10.1007/s12024-007-9003-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/08/2007] [Indexed: 12/01/2022]
Abstract
Epidemiologic data suggest that SIDS is related to the sleep state, but exiguous literature has addressed infants who had been awake at the time of sudden catastrophic deterioration and subsequent death. The aims of this study are to: (1) Report five infants who were awake at the onset of the lethal event, and (2) Discuss potential lethal pathophysiological events that may lead to these circumstances. The demographic and pathologic profiles of these cases are similar to SIDS. Altered responses to severe hypotension, bradycardia, and apnea, perhaps elicited by aspiration and mediated by cerebellar and vestibular structures, might be involved in the pathogenesis of these deaths. Comprehensive medical history review, investigation of the circumstances of death, thorough postmortem examination with ancillary studies, and preservation of tissues for gene testing, are crucial to explaining these deaths. Careful attention should be given to the awake or sleep state immediately prior to the sudden clinical collapse, and death of infants; those who were awake should be reported to enhance understanding of this phenomenon.
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Affiliation(s)
- Henry F Krous
- Department of Pathology, Rady Children's Hospital and Health Center, 3020 Children's Way, MC5007, San Diego, CA 92123, USA.
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