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C Sekhar V, Gulia KK, Deepti A, Chakrapani PSB, Baby S, Viswanathan G. Protection by Nano-Encapsulated Bacoside A and Bacopaside I in Seizure Alleviation and Improvement in Sleep- In Vitro and In Vivo Evidences. Mol Neurobiol 2024; 61:3296-3313. [PMID: 37987958 DOI: 10.1007/s12035-023-03741-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 10/24/2023] [Indexed: 11/22/2023]
Abstract
Therapeutic options to contain seizures, a transitional stage of many neuropathologies, are limited due to the blood-brain barrier (BBB). Herbal nanoparticle formulations can be employed to enhance seizure prognosis. Bacoside A (BM3) and bacopaside I (BM4) were isolated from Bacopa monnieri and synthesized as nanoparticles (BM3NP and BM4NP, respectively) for an effective delivery system to alleviate seizures and associated conditions. After physicochemical characterization, cell viability was assessed on mouse neuronal stem cells (mNSC) and neuroblastoma cells (N2a). Thereafter, anti-seizure effects, mitochondrial membrane potential (MMP), apoptosis, immunostaining and epileptic marker mRNA expression were determined in vitro. The seizure-induced changes in the cortical electroencephalogram (EEG), electromyography (EMG), Non-Rapid Eye Movement (NREM) and Rapid Eye Movement (REM) sleep were monitored in vivo in a kainic acid (KA)-induced rat seizure model. The sizes of BM3NPs and BM4NPs were 165.5 nm and 689.6 nm, respectively. They were biocompatible and also aided in neuroplasticity in mNSC. BM3NPs and BM4NPs depicted more than 50% cell viability in N2a cells, with IC50 values of 1609 and 2962 µg/mL, respectively. Similarly, these nanoparticles reduced the cytotoxicity of N2a cells upon KA treatment. Nanoparticles decreased the expression of epileptic markers like fractalkine, HMGB1, FOXO3a and pro-inflammatory cytokines (P < 0.05). They protected neurons from apoptosis and restored MMP. After administration of BM3NPs and BM4NPs, KA-treated rats attained a significant reduction in the epileptic spikes, sleep latency and an increase in NREM sleep duration. Results indicate the potential of BM3NPs and BM4NPs in neutralizing the KA-induced excitotoxic seizures in neurons.
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Affiliation(s)
- Vini C Sekhar
- Phytochemistry and Phytopharmacology Division, KSCSTE-Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Pacha-Palode, Thiruvananthapuram, 695562, Kerala, India
- University of Kerala, Thiruvananthapuram, 695034, Kerala, India
| | - Kamalesh K Gulia
- Division of Sleep Research, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, 695011, India
| | - Ayswaria Deepti
- Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin, 682022, Kerala, India
| | - P S Baby Chakrapani
- Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin, 682022, Kerala, India
| | - Sabulal Baby
- Phytochemistry and Phytopharmacology Division, KSCSTE-Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Pacha-Palode, Thiruvananthapuram, 695562, Kerala, India
| | - Gayathri Viswanathan
- Phytochemistry and Phytopharmacology Division, KSCSTE-Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Pacha-Palode, Thiruvananthapuram, 695562, Kerala, India.
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Kaczmarski P, Sochal M, Strzelecki D, Białasiewicz P, Gabryelska A. Influence of glutamatergic and GABAergic neurotransmission on obstructive sleep apnea. Front Neurosci 2023; 17:1213971. [PMID: 37521710 PMCID: PMC10372424 DOI: 10.3389/fnins.2023.1213971] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 06/26/2023] [Indexed: 08/01/2023] Open
Abstract
Glutamate and γ-aminobutyric acid (GABA) are the two main neurotransmitters in the human brain. The balance between their excitatory and inhibitory functions is crucial for maintaining the brain's physiological functions. Disturbance of glutamatergic or GABAergic neurotransmission leads to serious health problems including neurodegeneration, affective and sleep disorders. Both GABA and glutamate are involved in the control of the sleep-wake cycle. The disturbances in their function may cause sleep and sleep-related disorders. Obstructive sleep apnea (OSA) is the most common sleep respiratory disorder and is characterized by repetitive collapse of the upper airway resulting in intermittent hypoxia and sleep fragmentation. The complex pathophysiology of OSA is the basis of the development of numerous comorbid diseases. There is emerging evidence that GABA and glutamate disturbances may be involved in the pathogenesis of OSA, as well as its comorbidities. Additionally, the GABA/glutamate targeted pharmacotherapy may also influence the course of OSA, which is important in the implementation of wildly used drugs including benzodiazepines, anesthetics, and gabapentinoids. In this review, we summarize current knowledge on the influence of disturbances in glutamatergic and GABAergic neurotransmission on obstructive sleep apnea.
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Affiliation(s)
- Piotr Kaczmarski
- Department of Sleep Medicine and Metabolic Disorders, Medical University of Łódź, Łódź, Poland
| | - Marcin Sochal
- Department of Sleep Medicine and Metabolic Disorders, Medical University of Łódź, Łódź, Poland
| | - Dominik Strzelecki
- Department of Affective and Psychotic Disorders, Medical University of Łódź, Łódź, Poland
| | - Piotr Białasiewicz
- Department of Sleep Medicine and Metabolic Disorders, Medical University of Łódź, Łódź, Poland
| | - Agata Gabryelska
- Department of Sleep Medicine and Metabolic Disorders, Medical University of Łódź, Łódź, Poland
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Gabryelska A, Turkiewicz S, Ditmer M, Sochal M. Neurotrophins in the Neuropathophysiology, Course, and Complications of Obstructive Sleep Apnea-A Narrative Review. Int J Mol Sci 2023; 24:ijms24031808. [PMID: 36768132 PMCID: PMC9916304 DOI: 10.3390/ijms24031808] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 12/04/2022] [Accepted: 01/11/2023] [Indexed: 01/18/2023] Open
Abstract
Obstructive sleep apnea (OSA) is a disorder characterized by chronic intermittent hypoxia and sleep fragmentation due to recurring airway collapse during sleep. It is highly prevalent in modern societies, and due to its pleiotropic influence on the organism and numerous sequelae, it burdens patients and physicians. Neurotrophins (NTs), proteins that modulate the functioning and development of the central nervous system, such as brain-derived neurotrophic factor (BDNF), have been associated with OSA, primarily due to their probable involvement in offsetting the decline in cognitive functions which accompanies OSA. However, NTs influence multiple aspects of biological functioning, such as immunity. Thus, extensive evaluation of their role in OSA might enlighten the mechanism behind some of its elusive features, such as the increased risk of developing an immune-mediated disease or the association of OSA with cardiovascular diseases. In this review, we examine the interactions between NTs and OSA and discuss their contribution to OSA pathophysiology, complications, as well as comorbidities.
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Development and validation of a metabolite index for obstructive sleep apnea across race/ethnicities. Sci Rep 2022; 12:21805. [PMID: 36526671 PMCID: PMC9758170 DOI: 10.1038/s41598-022-26321-9] [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] [Received: 07/16/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Obstructive sleep apnea (OSA) is a common disorder characterized by recurrent episodes of upper airway obstruction during sleep resulting in oxygen desaturation and sleep fragmentation, and associated with increased risk of adverse health outcomes. Metabolites are being increasingly used for biomarker discovery and evaluation of disease processes and progression. Studying metabolomic associations with OSA in a diverse community-based cohort may provide insights into the pathophysiology of OSA. We aimed to develop and replicate a metabolite index for OSA and identify individual metabolites associated with OSA. We studied 219 metabolites and their associations with the apnea hypopnea index (AHI) and with moderate-severe OSA (AHI ≥ 15) in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) (n = 3507) using two methods: (1) association analysis of individual metabolites, and (2) least absolute shrinkage and selection operator (LASSO) regression to identify a subset of metabolites jointly associated with OSA, which was used to develop a metabolite index for OSA. Results were validated in the Multi-Ethnic Study of Atherosclerosis (MESA) (n = 475). When assessing the associations with individual metabolites, we identified seven metabolites significantly positively associated with OSA in HCHS/SOL (FDR p < 0.05), of which four associations-glutamate, oleoyl-linoleoyl-glycerol (18:1/18:2), linoleoyl-linoleoyl-glycerol (18:2/18:2) and phenylalanine, were replicated in MESA (one sided-p < 0.05). The OSA metabolite index, composed of 14 metabolites, was associated with a 50% increased risk for moderate-severe OSA (OR = 1.50 [95% CI 1.21-1.85] per 1 SD of OSA metabolite index, p < 0.001) in HCHS/SOL and 55% increased risk (OR = 1.55 [95% CI 1.10-2.20] per 1 SD of OSA metabolite index, p = 0.013) in MESA, both adjusted for demographics, lifestyle, and comorbidities. Similar albeit less significant associations were observed for AHI. Replication of the metabolite index in an independent multi-ethnic dataset demonstrates the robustness of metabolomic-based OSA index to population heterogeneity. Replicated metabolite associations may provide insights into OSA-related molecular and metabolic mechanisms.
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Martineau-Dussault MÈ, André C, Daneault V, Baril AA, Gagnon K, Blais H, Petit D, Montplaisir JY, Lorrain D, Bastien C, Hudon C, Descoteaux M, Boré A, Theaud G, Thompson C, Legault J, Martinez Villar GE, Lafrenière A, Lafond C, Gilbert D, Carrier J, Gosselin N. Medial temporal lobe and obstructive sleep apnea: Effect of sex, age, cognitive status and free-water. Neuroimage Clin 2022; 36:103235. [PMID: 36272339 PMCID: PMC9668668 DOI: 10.1016/j.nicl.2022.103235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 09/23/2022] [Accepted: 10/15/2022] [Indexed: 11/06/2022]
Abstract
Medial temporal structures, namely the hippocampus, the entorhinal cortex and the parahippocampal gyrus, are particularly vulnerable to Alzheimer's disease and hypoxemia. Here, we tested the associations between obstructive sleep apnea (OSA) severity and medial temporal lobe volumes in 114 participants aged 55-86 years (35 % women). We also investigated the impact of sex, age, cognitive status, and free-water fraction correction on these associations. Increased OSA severity was associated with larger hippocampal and entorhinal cortex volumes in women, but not in men. Greater OSA severity also correlated with increased hippocampal volumes in participants with amnestic mild cognitive impairment, but not in cognitively unimpaired participants, regardless of sex. Using free-water corrected volumes eliminated all significant associations with OSA severity. Therefore, the increase in medial temporal subregion volumes may possibly be due to edema. Whether these structural manifestations further progress to neuronal death in non-treated OSA patients should be investigated.
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Affiliation(s)
- Marie-Ève Martineau-Dussault
- Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord-de-l’Ile-de-Montréal, Montreal, Canada,Department of Psychology, Université de Montréal, Montreal, Canada
| | - Claire André
- Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord-de-l’Ile-de-Montréal, Montreal, Canada,Department of Psychology, Université de Montréal, Montreal, Canada
| | - Véronique Daneault
- Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord-de-l’Ile-de-Montréal, Montreal, Canada,Centre de recherche de l’Institut universitaire de gériatrie de Montréal, CIUSSS du Centre-Sud-de l’Île-de-Montréal, Montreal, Canada
| | - Andrée-Ann Baril
- Department of Psychiatry, McGill University, Montreal, Canada,Douglas Mental Health University Institute, CIUSSS de l'Ouest-de-l'Ile-de-Montréal, Montreal, Canada
| | - Katia Gagnon
- Hôpital en santé mentale Rivière-des-Prairies, CIUSSS du Nord-de-l’Ile-de-Montréal, Montreal, Canada,Department of Psychiatry, Université de Montréal, Montreal, Canada
| | - Hélène Blais
- Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord-de-l’Ile-de-Montréal, Montreal, Canada
| | - Dominique Petit
- Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord-de-l’Ile-de-Montréal, Montreal, Canada,Department of Psychiatry, Université de Montréal, Montreal, Canada
| | - Jacques Y. Montplaisir
- Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord-de-l’Ile-de-Montréal, Montreal, Canada,Department of Psychiatry, Université de Montréal, Montreal, Canada
| | - Dominique Lorrain
- Research Center on Aging, Institut universitaire de gériatrie de Sherbrooke, CIUSSS de l’Estrie, Sherbrooke, Canada,Department of Psychology, Université de Sherbrooke, Sherbrooke, Canada
| | - Célyne Bastien
- CERVO Research Center, Quebec City, Canada,École de psychologie, Université Laval, Quebec City, Canada
| | - Carol Hudon
- CERVO Research Center, Quebec City, Canada,École de psychologie, Université Laval, Quebec City, Canada
| | - Maxime Descoteaux
- Sherbrooke Connectivity Imaging Laboratory (SCIL), Université de Sherbrooke, Sherbrooke, Canada,Imeka Solutions Inc, Sherbrooke, Canada
| | - Arnaud Boré
- Centre de recherche de l’Institut universitaire de gériatrie de Montréal, CIUSSS du Centre-Sud-de l’Île-de-Montréal, Montreal, Canada,Sherbrooke Connectivity Imaging Laboratory (SCIL), Université de Sherbrooke, Sherbrooke, Canada,Imeka Solutions Inc, Sherbrooke, Canada
| | - Guillaume Theaud
- Sherbrooke Connectivity Imaging Laboratory (SCIL), Université de Sherbrooke, Sherbrooke, Canada,Imeka Solutions Inc, Sherbrooke, Canada
| | - Cynthia Thompson
- Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord-de-l’Ile-de-Montréal, Montreal, Canada
| | - Julie Legault
- Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord-de-l’Ile-de-Montréal, Montreal, Canada,Department of Psychology, Université de Montréal, Montreal, Canada
| | - Guillermo E. Martinez Villar
- Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord-de-l’Ile-de-Montréal, Montreal, Canada,Department of Psychology, Université de Montréal, Montreal, Canada
| | - Alexandre Lafrenière
- Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord-de-l’Ile-de-Montréal, Montreal, Canada,Department of Psychology, Université de Montréal, Montreal, Canada
| | - Chantal Lafond
- Department of Medecine, Université de Montréal, Montreal, Canada,Department of Pneumonology, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord-de-l’Ile-de-Montréal, Montreal, Canada
| | - Danielle Gilbert
- Department of Radiology, Radio-oncology and Nuclear Medicine, Université de Montréal, Montreal, Canada,Department of Radiology, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord-de-l’Ile-de-Montréal, Canada
| | - Julie Carrier
- Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord-de-l’Ile-de-Montréal, Montreal, Canada,Department of Psychology, Université de Montréal, Montreal, Canada,Centre de recherche de l’Institut universitaire de gériatrie de Montréal, CIUSSS du Centre-Sud-de l’Île-de-Montréal, Montreal, Canada
| | - Nadia Gosselin
- Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord-de-l’Ile-de-Montréal, Montreal, Canada,Department of Psychology, Université de Montréal, Montreal, Canada,Corresponding author at: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montréal, CIUSSS du Nord-de l’Ile-de-Montréal, 5400 Gouin Blvd. West, Office J-5135, Montreal, Quebec H4J 1C5, Canada.
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Marciante AB, Howard J, Kelly MN, Santiago Moreno J, Allen LL, Gonzalez-Rothi EJ, Mitchell GS. Dose-dependent phosphorylation of endogenous Tau by intermittent hypoxia in rat brain. J Appl Physiol (1985) 2022; 133:561-571. [PMID: 35861520 PMCID: PMC9448341 DOI: 10.1152/japplphysiol.00332.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/11/2022] [Accepted: 07/13/2022] [Indexed: 11/22/2022] Open
Abstract
Intermittent hypoxia, or intermittent low oxygen interspersed with normal oxygen levels, has differential effects that depend on the "dose" of hypoxic episodes (duration, severity, number per day, and number of days). Whereas "low dose" daily acute intermittent hypoxia (dAIH) elicits neuroprotection and neuroplasticity, "high dose" chronic intermittent hypoxia (CIH) similar to that experienced during sleep apnea elicits neuropathology. Sleep apnea is comorbid in >50% of patients with Alzheimer's disease-a progressive, neurodegenerative disease associated with brain amyloid and chronic Tau dysregulation (pathology). Although patients with sleep apnea present with higher Tau levels, it is unknown if sleep apnea through attendant CIH contributes to onset of Tau pathology. We hypothesized CIH characteristic of moderate sleep apnea would increase dysregulation of phosphorylated Tau (phospho-Tau) species in Sprague-Dawley rat hippocampus and prefrontal cortex. Conversely, we hypothesized that dAIH, a promising neurotherapeutic, has minimal impact on Tau phosphorylation. We report a dose-dependent intermittent hypoxia effect, with region-specific increases in 1) phospho-Tau species associated with human Tauopathies in the soluble form and 2) accumulated phospho-Tau in the insoluble fraction. The latter observation was particularly evident with higher CIH intensities. This important and novel finding is consistent with the idea that sleep apnea and attendant CIH have the potential to accelerate the progression of Alzheimer's disease and/or other Tauopathies.NEW & NOTEWORTHY Sleep apnea is highly prevalent in people with Alzheimer's disease, suggesting the potential to accelerate disease onset and/or progression. These studies demonstrate that intermittent hypoxia (IH) induces dose-dependent, region-specific Tau phosphorylation, and are the first to indicate that higher IH "doses" elicit both endogenous, (rat) Tau hyperphosphorylation and accumulation in the hippocampus. These findings are essential for development and implementation of new treatment strategies that minimize sleep apnea and its adverse impact on neurodegenerative diseases.
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Affiliation(s)
- Alexandria B Marciante
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, Florida
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
| | - John Howard
- Department of Neuroscience, University of Florida, Gainesville, Florida
- Center for Translational Research in Neurodegenerative Diseases, University of Florida, Gainesville, Florida
| | - Mia N Kelly
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, Florida
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
| | - Juan Santiago Moreno
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, Florida
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
| | - Latoya L Allen
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, Florida
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
| | - Elisa J Gonzalez-Rothi
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, Florida
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
| | - Gordon S Mitchell
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, Florida
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
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Neuroprotective strategies for acute ischemic stroke: Targeting oxidative stress and prolyl hydroxylase domain inhibition in synaptic signalling. BRAIN DISORDERS 2022. [DOI: 10.1016/j.dscb.2022.100030] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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Yiangou A, Mitchell JL, Nicholls M, Chong YJ, Vijay V, Wakerley BR, Lavery GG, Tahrani AA, Mollan SP, Sinclair AJ. Obstructive sleep apnoea in women with idiopathic intracranial hypertension: a sub-study of the idiopathic intracranial hypertension weight randomised controlled trial (IIH: WT). J Neurol 2021; 269:1945-1956. [PMID: 34420064 PMCID: PMC8940816 DOI: 10.1007/s00415-021-10700-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/02/2021] [Accepted: 07/03/2021] [Indexed: 12/15/2022]
Abstract
Objective Obesity is a risk factor for idiopathic intracranial hypertension (IIH) and obstructive sleep apnoea (OSA). We aimed to determine the prevalence of OSA in IIH and evaluate the diagnostic performance of OSA screening tools in IIH. Additionally, we evaluated the relationship between weight loss, OSA and IIH over 12 months. Methods A sub-study of a multi-centre, randomised controlled parallel group trial comparing the impact of bariatric surgery vs. community weight management intervention (CWI) on IIH-related outcomes over 12 months (IIH:WT). OSA was assessed using home-based polygraphy (ApneaLink Air, ResMed) at baseline and 12 months. OSA was defined as an apnoea–hypopnoea index (AHI) ≥ 15 or ≥ 5 with excessive daytime sleepiness (Epworth Sleepiness Scale ≥11 ). Results Of the 66 women in the IIH: WT trial, 46 were included in the OSA sub-study. OSA prevalence was 47% (n = 19). The STOP-BANG had the highest sensitivity (84%) compared to the Epworth Sleepiness Scale (69%) and Berlin (68%) to detect OSA. Bariatric surgery resulted in greater reductions in AHI vs. CWI (median [95%CI] AHI reduction of – 2.8 [ – 11.9, 0.7], p = 0.017). Over 12 months there was a positive association between changes in papilloedema and AHI (r = 0.543, p = 0.045), despite adjustment for changes in the body mass index (R2 = 0.522, p = 0.017). Conclusion OSA is common in IIH and the STOP-BANG questionnaire was the most sensitive screening tool. Bariatric surgery improved OSA in patients with IIH. The improvement in AHI was associated with improvement in papilloedema independent of weight loss. Whether OSA treatment has beneficial impact on papilloedema warrants further evaluation. Trial registration number IIH: WT is registered as ISRCTN40152829 and on ClinicalTrials.gov as NCT02124486 (28/04/2014). Supplementary Information The online version contains supplementary material available at 10.1007/s00415-021-10700-9.
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Affiliation(s)
- Andreas Yiangou
- Metabolic Neurology, Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, B15 2TH, UK.,Department of Neurology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, B15 2TH, UK
| | - James L Mitchell
- Metabolic Neurology, Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, B15 2TH, UK.,Department of Neurology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, B15 2TH, UK
| | - Matthew Nicholls
- Metabolic Neurology, Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, B15 2TH, UK
| | - Yu Jeat Chong
- Birmingham Neuro-Ophthalmology, Ophthalmology Department, University Hospitals Birmingham NHS Foundation Trust, Birmingham, Birmingham, B15 2TH, UK
| | - Vivek Vijay
- Metabolic Neurology, Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, B15 2TH, UK.,Department of Neurology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, B15 2TH, UK
| | - Benjamin R Wakerley
- Department of Neurology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, B15 2TH, UK
| | - Gareth G Lavery
- Metabolic Neurology, Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, B15 2TH, UK.,Department of Neurology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, B15 2TH, UK
| | - Abd A Tahrani
- Metabolic Neurology, Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, B15 2TH, UK.,Department of Endocrinology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, B15 2TH, UK
| | - Susan P Mollan
- Birmingham Neuro-Ophthalmology, Ophthalmology Department, University Hospitals Birmingham NHS Foundation Trust, Birmingham, Birmingham, B15 2TH, UK
| | - Alexandra J Sinclair
- Metabolic Neurology, Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK. .,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, B15 2TH, UK. .,Department of Neurology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, B15 2TH, UK.
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9
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Intermittent Hypoxia and Effects on Early Learning/Memory: Exploring the Hippocampal Cellular Effects of Pediatric Obstructive Sleep Apnea. Anesth Analg 2021; 133:93-103. [PMID: 33234943 DOI: 10.1213/ane.0000000000005273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
This review provides an update on the neurocognitive phenotype of pediatric obstructive sleep apnea (OSA). Pediatric OSA is associated with neurocognitive deficits involving memory, learning, and executive functioning. Adenotonsillectomy (AT) is presently accepted as the first-line surgical treatment for pediatric OSA, but the executive function deficits do not resolve postsurgery, and the timeline for recovery remains unknown. This finding suggests that pediatric OSA potentially causes irreversible damage to multiple areas of the brain. The focus of this review is the hippocampus, 1 of the 2 major sites of postnatal neurogenesis, where new neurons are formed and integrated into existing circuitry and the mammalian center of learning/memory functions. Here, we review the clinical phenotype of pediatric OSA, and then discuss existing studies of OSA on different cell types in the hippocampus during critical periods of development. This will set the stage for future study using preclinical models to understand the pathogenesis of persistent neurocognitive dysfunction in pediatric OSA.
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Xu L, Yang Y, Chen J. The role of reactive oxygen species in cognitive impairment associated with sleep apnea. Exp Ther Med 2020; 20:4. [PMID: 32934669 PMCID: PMC7471880 DOI: 10.3892/etm.2020.9132] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 02/07/2020] [Indexed: 02/07/2023] Open
Abstract
Obstructive sleep apnea (OSA), a common breathing and sleeping disorder, is associated with a broad range of neurocognitive difficulties. Intermittent hypoxia (IH), one major characteristic of OSA, has been shown to impair learning and memory due to increased levels of reactive oxygen species (ROS). Under normal conditions, ROS are produced in low concentrations and act as signaling molecules in different processes. However, IH treatment leads to elevated ROS production via multiple pathways, including mitochondrial electron transport chain dysfunction and in particular complex I dysfunction, and induces oxidative tissue damage. Moreover, elevated ROS results in the accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) and increased activity of peroxisomes, such as NADPH oxidase, xanthine oxidase and phospholipase A2. Furthermore, oxidative tissue damage has been found in regions of the brains of patients with OSA, including the cortex and hippocampus, which are associated with memory and executive function. Furthermore, increased ROS levels in these regions of the brain induce damage via inflammation, apoptosis, ER stress and neuronal activity disturbance. The present review focuses on the mechanism of excessive ROS production in an OSA model and the relationship between ROS and cognitive impairment.
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Affiliation(s)
- Linhao Xu
- Department of Cardiology, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310006, P.R. China.,Department of Pathology, School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, Zhejiang 310053, P.R. China.,Translational Medicine Research Center, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310006, P.R. China
| | - Yibo Yang
- College of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 201424, P.R. China
| | - Jian Chen
- Department of Pathology, School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, Zhejiang 310053, P.R. China
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11
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Flores KR, Viccaro F, Aquilini M, Scarpino S, Ronchetti F, Mancini R, Di Napoli A, Scozzi D, Ricci A. Protective role of brain derived neurotrophic factor (BDNF) in obstructive sleep apnea syndrome (OSAS) patients. PLoS One 2020; 15:e0227834. [PMID: 31951637 PMCID: PMC6968866 DOI: 10.1371/journal.pone.0227834] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 12/30/2019] [Indexed: 02/06/2023] Open
Abstract
Obstructive sleep apnea syndrome (OSAS) is a common disorder characterized by repeated episodes of upper airways collapse during the sleep. The following intermittent hypoxia triggers a state of chronic inflammation, which also interests the nervous system leading to neuronal damage and increased risk of cognitive impairment. Brain derived neurotrophic factor (BDNF) is a growth factor often associated with neuroplasticity and neuroprotection whose levels increase in several condition associated with neuronal damage. However, whether patients affected by OSAS have altered BDNF levels and whether such alteration may be reflective of their cognitive impairment is still controversial. Here we show that, when compared to healthy control volunteers, OSAS patients have increased serum levels of BDNF. Moreover, OSAS patients with the higher levels of BDNF also have reduced neurocognitive impairment as measured by The Montreal Cognitive Assessment (MoCA) questionnaire. Treatment with standard non-invasive mechanical ventilation (CPAP) also was able to ameliorate the level of cognitive impairment. Altogether our results indicate that BDNF levels represent a neuroprotective response to intermittent hypoxia in OSAS patients.
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Affiliation(s)
- Krisstopher Richard Flores
- Department of Clinical and Molecular Medicine, Division of Respiratory Diseases, Sant’Andrea Hospital, Sapienza University, Rome, Italy
| | - Fausta Viccaro
- Department of Clinical and Molecular Medicine, Division of Respiratory Diseases, Sant’Andrea Hospital, Sapienza University, Rome, Italy
| | - Mauro Aquilini
- Department of Clinical and Molecular Medicine, Division of Respiratory Diseases, Sant’Andrea Hospital, Sapienza University, Rome, Italy
| | - Stefania Scarpino
- Department of Clinical and Molecular Medicine, Division of Respiratory Diseases, Sant’Andrea Hospital, Sapienza University, Rome, Italy
| | - Francesco Ronchetti
- Department of Clinical and Molecular Medicine, Division of Respiratory Diseases, Sant’Andrea Hospital, Sapienza University, Rome, Italy
| | - Rita Mancini
- Department of Clinical and Molecular Medicine, Division of Respiratory Diseases, Sant’Andrea Hospital, Sapienza University, Rome, Italy
| | - Arianna Di Napoli
- Department of Clinical and Molecular Medicine, Division of Respiratory Diseases, Sant’Andrea Hospital, Sapienza University, Rome, Italy
| | - Davide Scozzi
- Department of Surgery, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Alberto Ricci
- Department of Clinical and Molecular Medicine, Division of Respiratory Diseases, Sant’Andrea Hospital, Sapienza University, Rome, Italy
- * E-mail:
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12
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Li W, Yang S, Yu FY, Zhao Y, Sun ZM, An JR, Ji E. Hydrogen ameliorates chronic intermittent hypoxia-induced neurocognitive impairment via inhibiting oxidative stress. Brain Res Bull 2018; 143:225-233. [DOI: 10.1016/j.brainresbull.2018.09.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 09/13/2018] [Accepted: 09/18/2018] [Indexed: 12/21/2022]
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13
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Macey PM, Prasad JP, Ogren JA, Moiyadi AS, Aysola RS, Kumar R, Yan-Go FL, Woo MA, Albert Thomas M, Harper RM. Sex-specific hippocampus volume changes in obstructive sleep apnea. NEUROIMAGE-CLINICAL 2018; 20:305-317. [PMID: 30101062 PMCID: PMC6083433 DOI: 10.1016/j.nicl.2018.07.027] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 07/05/2018] [Accepted: 07/25/2018] [Indexed: 01/24/2023]
Abstract
Introduction Obstructive sleep apnea (OSA) patients show hippocampal-related autonomic and neurological symptoms, including impaired memory and depression, which differ by sex, and are mediated in distinct hippocampal subfields. Determining sites and extent of hippocampal sub-regional injury in OSA could reveal localized structural damage linked with OSA symptoms. Methods High-resolution T1-weighted images were collected from 66 newly-diagnosed, untreated OSA (mean age ± SD: 46.3 ± 8.8 years; mean AHI ± SD: 34.1 ± 21.5 events/h;50 male) and 59 healthy age-matched control (46.8 ± 9.0 years;38 male) participants. We added age-matched controls with T1-weighted scans from two datasets (IXI, OASIS-MRI), for 979 controls total (426 male/46.5 ± 9.9 years). We segmented the hippocampus and analyzed surface structure with “FSL FIRST” software, scaling volumes for brain size, and evaluated group differences with ANCOVA (covariates: total-intracranial-volume, sex; P < .05, corrected). Results In OSA relative to controls, the hippocampus showed small areas larger volume bilaterally in CA1 (surface displacement ≤0.56 mm), subiculum, and uncus, and smaller volume in right posterior CA3/dentate (≥ − 0.23 mm). OSA vs. control males showed higher bilateral volume (≤0.61 mm) throughout CA1 and subiculum, extending to head and tail, with greater right-sided increases; lower bilateral volumes (≥ − 0.45 mm) appeared in mid- and posterior-CA3/dentate. OSA vs control females showed only right-sided effects, with increased CA1 and subiculum/uncus volumes (≤0.67 mm), and decreased posterior CA3/dentate volumes (≥ − 0.52 mm). Unlike males, OSA females showed volume decreases in the right hippocampus head and tail. Conclusions The hippocampus shows lateralized and sex-specific, OSA-related regional volume differences, which may contribute to sex-related expression of symptoms in the sleep disorder. Volume increases suggest inflammation and glial activation, whereas volume decreases suggest long-lasting neuronal injury; both processes may contribute to dysfunction in OSA. The hippocampus in OSA shows areas of increased and decreased volume. The injury is sex-specific, in subregions related to symptoms in females and males. Injury may be inflammation (volume increases) or cell death (volume decreases).
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Affiliation(s)
- Paul M Macey
- UCLA School of Nursing, University of California at Los Angeles, Los Angeles, CA 90095, United States; Brain Research Institute, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States.
| | - Janani P Prasad
- UCLA School of Nursing, University of California at Los Angeles, Los Angeles, CA 90095, United States
| | - Jennifer A Ogren
- Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States
| | - Ammar S Moiyadi
- Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States
| | - Ravi S Aysola
- Medicine-Division of Pulmonary and Critical Care, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States
| | - Rajesh Kumar
- Brain Research Institute, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States; Anesthesiology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States; Radiological Sciences, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States
| | - Frisca L Yan-Go
- Department of Neurology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States
| | - Mary A Woo
- UCLA School of Nursing, University of California at Los Angeles, Los Angeles, CA 90095, United States
| | - M Albert Thomas
- Radiological Sciences, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States
| | - Ronald M Harper
- Brain Research Institute, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States; Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States
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14
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Macey PM, Sarma MK, Prasad JP, Ogren JA, Aysola R, Harper RM, Thomas MA. Obstructive sleep apnea is associated with altered midbrain chemical concentrations. Neuroscience 2017; 363:76-86. [PMID: 28893651 PMCID: PMC5983363 DOI: 10.1016/j.neuroscience.2017.09.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 08/25/2017] [Accepted: 09/03/2017] [Indexed: 12/28/2022]
Abstract
Obstructive sleep apnea (OSA) is accompanied by altered structure and function in cortical, limbic, brainstem, and cerebellar regions. The midbrain is relatively unexamined, but contains many integrative nuclei which mediate physiological functions that are disrupted in OSA. We therefore assessed the chemistry of the midbrain in OSA in this exploratory study. We used a recently developed accelerated 2D magnetic resonance spectroscopy (2D-MRS) technique, compressed sensing-based 4D echo-planar J-resolved spectroscopic imaging (4D-EP-JRESI), to measure metabolites in the midbrain of 14 OSA (mean age±SD:54.6±10.6years; AHI:35.0±19.4; SAO2 min:83±7%) and 26 healthy control (50.7±8.5years) subjects. High-resolution T1-weighted scans allowed voxel localization. MRS data were processed with custom MATLAB-based software, and metabolite ratios calculated with respect to the creatine peak using a prior knowledge fitting (ProFit) algorithm. The midbrain in OSA showed decreased N-acetylaspartate (NAA; OSA:1.24±0.43, Control:1.47±0.41; p=0.03; independent samples t-test), a marker of neuronal viability. Increased levels in OSA over control subjects appeared in glutamate (Glu; OSA:1.23±0.57, Control:0.98±0.33; p=0.03), ascorbate (Asc; OSA:0.56±0.28, Control:0.42±0.20; (50.7±8.5years; p=0.03), and myo-inositol (mI; OSA:0.96±0.48, Control:0.72±0.35; p=0.03). No differences between groups appeared in γ-aminobutyric acid (GABA) or taurine. The midbrain in OSA patients shows decreased NAA, indicating neuronal injury or dysfunction. Higher Glu levels may reflect excitotoxic processes and astrocyte activation, and higher mI is also consistent with glial activation. Higher Asc levels may result from oxidative stress induced by intermittent hypoxia in OSA. Additionally, Asc and Glu are involved with glutamatergic processes, which are likely upregulated in the midbrain nuclei of OSA patients. The altered metabolite levels help explain dysfunction and structural deficits in the midbrain of OSA patients.
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Key Words
- Asc, ascorbate
- Asp, aspartate
- Ch, choline
- GABA, gamma-aminobutyric acid
- GPC, glycerophosphorylcholine
- GSH, glutathione
- Gln, glutamine
- Glu, glutamate
- Gly, glycine
- NAA, N-acetylaspartate
- NAAG, N-acetylaspartate glutamate
- PCh, phosphocholine
- PE, phosphoethanolamine
- Scy, scyllo-inositol
- Tau, taurine
- Thr, threonine
- autonomic
- intermittent hypoxia
- mI, myo-inositol
- magnetic resonance spectroscopy
- periaqueductal gray
- respiration
- sleep-disordered breathing
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Affiliation(s)
- Paul M Macey
- School of Nursing, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States; Brain Research Institute, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States.
| | - Manoj K Sarma
- Department of Radiological Sciences, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States
| | - Janani P Prasad
- School of Nursing, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States
| | - Jennifer A Ogren
- Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States
| | - Ravi Aysola
- Department of Medicine (Division of Pulmonary and Critical Care), David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States
| | - Ronald M Harper
- Brain Research Institute, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States; Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States
| | - M Albert Thomas
- Department of Radiological Sciences, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, United States
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15
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The Effects of Obstructive Sleep Apnea Syndrome on the Dentate Gyrus and Learning and Memory in Children. J Neurosci 2017; 37:4280-4288. [PMID: 28320844 DOI: 10.1523/jneurosci.3583-16.2017] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 02/15/2017] [Accepted: 02/17/2017] [Indexed: 11/21/2022] Open
Abstract
Obstructive sleep apnea syndrome (OSAS) is associated with intermittent hypoxia and sleep loss. In children, impairments of cognitive function are important manifestations, but the underlying pathology is unknown. We hypothesized that OSAS would affect the dentate gyrus, a hippocampal subdivision essential to neurogenesis and cognition, and that this impact would further affect cognitive function in children. In children with OSAS (n = 11) and control subjects (n = 12; age and sex matched), we performed diffusion tensor imaging and structural MRI, polysomnography, and neuropsychological assessments. We found that OSAS was associated with decreased mean diffusivity of the left dentate gyrus (p = 0.002; false discovery rate corrected; adjusting for sex, age, and body mass index), showing a large effect size (partial η2 = 0.491), but not with any other structural measures across the brain. Decreased dentate gyrus mean diffusivity correlated with a higher apnea hypopnea index (Spearman's r = -0.50, p = 0.008) and a greater arousal index (r = -0.44, p = 0.017). OSAS did not significantly affect neuropsychological measures (p values >0.5); however, a lower verbal learning score correlated with lower dentate gyrus mean diffusivity (r = 0.54, p = 0.004). Path analysis demonstrated that dentate gyrus mean diffusivity mediates the impact of OSAS on verbal learning capacity. Finally, the diagnostic accuracy of a regression model based on dentate gyrus mean diffusivity reached 85.8% (cross validated). This study demonstrates a likely pathway of effects of OSAS on neurocognitive function in children, as well as potential utility of the dentate gyrus mean diffusivity as an early marker of brain pathology in children with OSAS.SIGNIFICANCE STATEMENT In this study we investigate the relationships between dentate gyrus structure, hippocampus-dependent cognition, and obstructive sleep apnea syndrome (OSAS). We demonstrate lower mean diffusivity of the dentate gyrus in children with OSAS, which correlates with a lower verbal learning and memory score. This study provides new evidence of disrupted microstructure of the dentate gyrus in children with OSAS that may help explain some of the neurocognitive deficits described in these children.
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16
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Lipford MC, Ramar K, Liang YJ, Lin CW, Chao YT, An J, Chiu CH, Tsai YJ, Shu CH, Lee FP, Chiang RPY. Serotnin as a possible biomarker in obstructive sleep apnea. Sleep Med Rev 2016; 28:125-32. [DOI: 10.1016/j.smrv.2015.08.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 08/07/2015] [Accepted: 08/07/2015] [Indexed: 01/21/2023]
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17
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Xu LH, Xie H, Shi ZH, Du LD, Wing YK, Li AM, Ke Y, Yung WH. Critical Role of Endoplasmic Reticulum Stress in Chronic Intermittent Hypoxia-Induced Deficits in Synaptic Plasticity and Long-Term Memory. Antioxid Redox Signal 2015; 23:695-710. [PMID: 25843188 PMCID: PMC4580307 DOI: 10.1089/ars.2014.6122] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
AIMS This study examined the role of endoplasmic reticulum (ER) stress in mediating chronic intermittent hypoxia (IH)-induced neurocognitive deficits. We designed experiments to demonstrate that ER stress is initiated in the hippocampus under chronic IH and determined its role in apoptotic cell death, impaired synaptic structure and plasticity, and memory deficits. RESULTS Two weeks of IH disrupted ER fine structure and upregulated ER stress markers, glucose-regulated protein 78, caspase-12, and C/EBP homologous protein, in the hippocampus, which could be suppressed by ER stress inhibitors, tauroursodeoxycholic acid (TUDCA) and 4-phenylbutyric acid. Meanwhile, ER stress induced apoptosis via decreased Bcl-2, promoted reactive oxygen species production, and increased malondialdehyde formation and protein carbonyl, as well as suppressed mitochondrial function. These effects were largely prevented by ER stress inhibitors. On the other hand, suppression of oxidative stress could reduce ER stress. In addition, the length of the synaptic active zone and number of mature spines were reduced by IH. Long-term recognition memory and spatial memory were also impaired, which was accompanied by reduced long-term potentiation in the Schaffer collateral pathway. These effects were prevented by coadministration of the TUDCA. INNOVATION AND CONCLUSION These results show that ER stress plays a critical role in underlying memory deficits in obstructive sleep apnea (OSA)-associated IH. Attenuators of ER stress may serve as novel adjunct therapeutic agents for ameliorating OSA-induced neurocognitive impairment.
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Affiliation(s)
- Lin-Hao Xu
- 1 Faculty of Medicine, School of Biomedical Sciences, The Chinese University of Hong Kong , Shatin, Hong Kong, China
| | - Hui Xie
- 1 Faculty of Medicine, School of Biomedical Sciences, The Chinese University of Hong Kong , Shatin, Hong Kong, China
| | - Zhi-Hui Shi
- 1 Faculty of Medicine, School of Biomedical Sciences, The Chinese University of Hong Kong , Shatin, Hong Kong, China
| | - Li-Da Du
- 1 Faculty of Medicine, School of Biomedical Sciences, The Chinese University of Hong Kong , Shatin, Hong Kong, China
| | - Yun-Kwok Wing
- 2 Department of Psychiatry, Prince of Wales Hospital , Shatin, Hong Kong, China
| | - Albert M Li
- 3 Department of Pediatrics, Prince of Wales Hospital , Shatin, Hong Kong, China
| | - Ya Ke
- 1 Faculty of Medicine, School of Biomedical Sciences, The Chinese University of Hong Kong , Shatin, Hong Kong, China
| | - Wing-Ho Yung
- 1 Faculty of Medicine, School of Biomedical Sciences, The Chinese University of Hong Kong , Shatin, Hong Kong, China
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18
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Baril AA, Gagnon K, Arbour C, Soucy JP, Montplaisir J, Gagnon JF, Gosselin N. Regional Cerebral Blood Flow during Wakeful Rest in Older Subjects with Mild to Severe Obstructive Sleep Apnea. Sleep 2015; 38:1439-49. [PMID: 25761981 DOI: 10.5665/sleep.4986] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 01/31/2015] [Indexed: 11/03/2022] Open
Abstract
OBJECTIVES To evaluate changes in regional cerebral blood flow (rCBF) during wakeful rest in older subjects with mild to severe obstructive sleep apnea (OSA) and healthy controls, and to identify markers of OSA severity that predict altered rCBF. DESIGN High-resolution (99m)Tc-HMPAO SPECT imaging during wakeful rest. SETTING Research sleep laboratory affiliated with a University hospital. PARTICIPANTS Fifty untreated OSA patients aged between 55 and 85 years, divided into mild, moderate, and severe OSA, and 20 age-matched healthy controls. INTERVENTIONS N/A. MEASUREMENTS Using statistical parametric mapping, rCBF was compared between groups and correlated with clinical, respiratory, and sleep variables. RESULTS Whereas no rCBF change was observed in mild and moderate groups, participants with severe OSA had reduced rCBF compared to controls in the left parietal lobules, left precentral gyrus, bilateral postcentral gyri, and right precuneus. Reduced rCBF in these regions and in areas of the bilateral frontal and left temporal cortex was associated with more hypopneas, snoring, hypoxemia, and sleepiness. Higher apnea, microarousal, and body mass indexes were correlated to increased rCBF in the basal ganglia, insula, and limbic system. CONCLUSIONS While older individuals with severe obstructive sleep apnea (OSA) had hypoperfusion in the sensorimotor and parietal areas, respiratory variables and subjective sleepiness were correlated with extended regions of hypoperfusion in the lateral cortex. Interestingly, OSA severity, sleep fragmentation, and obesity correlated with increased perfusion in subcortical and medial cortical regions. Anomalies with such a distribution could result in cognitive deficits and reflect impaired vascular regulation, altered neuronal integrity, and/or undergoing neurodegenerative processes.
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Affiliation(s)
- Andrée-Ann Baril
- Center for Advanced Research in Sleep Medicine (CARSM), Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, Canada.,Université de Montréal, Department of Psychiatry, Montreal, Quebec, Canada
| | - Katia Gagnon
- Center for Advanced Research in Sleep Medicine (CARSM), Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, Canada.,Université du Québec à Montréal, Department of Psychology, Montreal, Quebec, Canada
| | - Caroline Arbour
- Center for Advanced Research in Sleep Medicine (CARSM), Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, Canada.,Université de Montréal, Department of Psychology, Montreal, Quebec, Canada
| | - Jean-Paul Soucy
- McGill University, McConnell Brain Imaging Centre, Montreal, Quebec, Canada
| | - Jacques Montplaisir
- Center for Advanced Research in Sleep Medicine (CARSM), Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, Canada.,Université de Montréal, Department of Psychiatry, Montreal, Quebec, Canada
| | - Jean-François Gagnon
- Center for Advanced Research in Sleep Medicine (CARSM), Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, Canada.,Université du Québec à Montréal, Department of Psychology, Montreal, Quebec, Canada
| | - Nadia Gosselin
- Center for Advanced Research in Sleep Medicine (CARSM), Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, Canada.,Université de Montréal, Department of Psychology, Montreal, Quebec, Canada
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Bahia CMCDS, Pereira JS. Obstructive sleep apnea and neurodegenerative diseases: A bidirectional relation. Dement Neuropsychol 2015; 9:9-15. [PMID: 29213936 PMCID: PMC5618986 DOI: 10.1590/s1980-57642015dn91000003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 09/10/2014] [Indexed: 12/11/2022] Open
Abstract
Sleep disorders are common during the clinical course of the main neurodegenerative diseases. Among these disorders, obstructive sleep apnea has been extensively studied in the last decade and recent knowledge regarding its relationship with the neurodegenerative process points a bidirectional relationship. Neurodegenerative diseases can lead to functional changes in the respiratory system that facilitate the emergence of apnea. On the other hand, obstructive sleep apnea itself can lead to acceleration of neuronal death due to intermittent hypoxia. Considering that obstructive sleep apnea is a potentially treatable condition, its early identification and intervention could have a positive impact on the management of patients with neurodegenerative diseases.
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Affiliation(s)
- Christianne Martins Corrêa da Silva Bahia
- Setor de Distúrbios do Movimento/ Neurologia/
Hospital Universitário Pedro Ernesto/ Universidade do Estado do Rio de
Janeiro(UERJ)
- Pós Graduação Stricto Sensu em
Ciências Médicas/Faculdade de Ciências Médicas/
Universidade do Estado do Rio de Janeiro
- Serviço Interdisciplinar de Medicina do
Sono/Hospital Universitário Pedro Ernesto/ Universidade do Estado do Rio de
Janeiro
| | - João Santos Pereira
- Setor de Distúrbios do Movimento/ Neurologia/
Hospital Universitário Pedro Ernesto/ Universidade do Estado do Rio de
Janeiro(UERJ)
- Pós Graduação Stricto Sensu em
Ciências Médicas/Faculdade de Ciências Médicas/
Universidade do Estado do Rio de Janeiro
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20
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Akhan G, Songu M, Ayik SO, Altay C, Kalemci S. Correlation between hippocampal sulcus width and severity of obstructive sleep apnea syndrome. Eur Arch Otorhinolaryngol 2014; 272:3763-8. [PMID: 25502740 DOI: 10.1007/s00405-014-3422-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 11/28/2014] [Indexed: 12/28/2022]
Abstract
The aim of the present study was to evaluate the relationship between obstructive sleep apnea syndrome (OSAS) severity and the hippocampal sulcus width in a cohort of subjects with OSAS and controls. A total of 149 OSAS patients and 60 nonapneic controls were included in the study. Overnight polysomnograpy was performed in all patients. Hippocampal sulcus width of the patients was measured by a radiologist blinded to the diagnosis of the patients. Other variables noted for each patient were as follows: gender, age, body mass index, apnea hypopnea index, Epworth sleepiness scale, sleep efficacy, mean saturation, lowest O2 saturation, longest apnea duration, neck circumference, waist circumference, hip circumference. A total of 149 OSAS patients were divided into three groups: mild OSAS (n = 54), moderate OSAS (n = 40), severe OSAS (n = 55) groups. The control group consisted of patients with AHI <5 (n = 60). Hippocampal sulcus width was 1.6 ± 0.83 mm in the control group; while 1.9 ± 0.81 mm in mild OSAS, 2.1 ± 0.60 mm in moderate OSAS, and 2.9 ± 0.58 mm in severe OSAS groups (p < 0.001). Correlation analysis of variables revealed that apnea hypopnea index (rs = 0.483, p < 0.001) was positively correlated with hippocampal sulcus width. Our findings demonstrated that severity of OSAS might be associated with various pathologic mechanisms including increased hippocampal sulcus width.
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Affiliation(s)
- Galip Akhan
- Faculty of Medicine, Department of Neurology, Izmir Katip Celebi University, Izmir, Turkey
| | - Murat Songu
- Department of Otorhinolaryngology, Ataturk Training and Research Hospital, Izmir Katip Celebi University, Izmir, Turkey.
| | - Sibel Oktem Ayik
- Faculty of Medicine, Department of Chest Diseases, Izmir Katip Celebi University, Izmir, Turkey
| | - Canan Altay
- Faculty of Medicine, Department of Radiology, Dokuz Eylul University, Izmir, Turkey
| | - Serdar Kalemci
- Faculty of Medicine, Department of Chest Diseases, Mugla University, Mugla, Turkey
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Intracranial hypertension associated with obstructive sleep apnea: a discussion of potential etiologic factors. Med Hypotheses 2014; 83:792-7. [PMID: 25456788 DOI: 10.1016/j.mehy.2014.10.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Revised: 09/07/2014] [Accepted: 10/14/2014] [Indexed: 01/02/2023]
Abstract
Obstructive sleep apnea has been shown to increase intracranial pressure, and to be a secondary cause of intracranial hypertension. There are a few theories that attempt to explain this relationship, however there is little data, and even less recognition among physicians that this actually occurs. This paper discusses multiple pieces of data, from anatomical correlates to biochemical information involving neuro-excitotoxicity, as well as hematologic factors and issues surrounding brain edema and blood-brain barrier dysfunction. A complex paradigm for how obstructive sleep apnea may lead to increased intracranial pressure is thus proposed. In addition, suggestions are made for how obstructive sleep apnea must as a result be managed differently in the setting of idiopathic intracranial hypertension.
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Angelo MF, Aguirre A, Avilés Reyes RX, Villarreal A, Lukin J, Melendez M, Vanasco V, Barker P, Alvarez S, Epstein A, Jerusalinsky D, Ramos AJ. The proinflammatory RAGE/NF-κB pathway is involved in neuronal damage and reactive gliosis in a model of sleep apnea by intermittent hypoxia. PLoS One 2014; 9:e107901. [PMID: 25265561 PMCID: PMC4180086 DOI: 10.1371/journal.pone.0107901] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 08/17/2014] [Indexed: 11/18/2022] Open
Abstract
Sleep apnea (SA) causes long-lasting changes in neuronal circuitry, which persist even in patients successfully treated for the acute effects of the disease. Evidence obtained from the intermittent hypoxia (IH) experimental model of SA has shown neuronal death, impairment in learning and memory and reactive gliosis that may account for cognitive and structural alterations observed in human patients. However, little is known about the mechanism controlling these deleterious effects that may be useful as therapeutic targets in SA. The Receptor for Advanced Glycation End products (RAGE) and its downstream effector Nuclear Factor Kappa B (NF-κB) have been related to neuronal death and astroglial conversion to the pro-inflammatory neurodegenerative phenotype. RAGE expression and its ligand S100B were shown to be increased in experimental models of SA. We here used dissociated mixed hippocampal cell cultures and male Wistar rats exposed to IH cycles and observed that NF-κB is activated in glial cells and neurons after IH. To disclose the relative contribution of the S100B/RAGE/NF-κB pathway to neuronal damage and reactive gliosis after IH we performed sequential loss of function studies using RAGE or S100B neutralizing antibodies, a herpes simplex virus (HSV)-derived amplicon vector that induces the expression of RAGEΔcyto (dominant negative RAGE) and a chemical blocker of NF-κB. Our results show that NF-κB activation peaks 3 days after IH exposure, and that RAGE or NF-κB blockage during this critical period significantly improves neuronal survival and reduces reactive gliosis. Both in vitro and in vivo, S100B blockage altered reactive gliosis but did not have significant effects on neuronal survival. We conclude that both RAGE and downstream NF-κB signaling are centrally involved in the neuronal alterations found in SA models, and that blockage of these pathways is a tempting strategy for preventing neuronal degeneration and reactive gliosis in SA.
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Affiliation(s)
- Maria Florencia Angelo
- Instituto de Biología Celular y Neurociencia “Prof. E. De Robertis”, Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Alejandra Aguirre
- Instituto de Biología Celular y Neurociencia “Prof. E. De Robertis”, Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Rolando X. Avilés Reyes
- Instituto de Biología Celular y Neurociencia “Prof. E. De Robertis”, Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Alejandro Villarreal
- Instituto de Biología Celular y Neurociencia “Prof. E. De Robertis”, Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Jerónimo Lukin
- Instituto de Biología Celular y Neurociencia “Prof. E. De Robertis”, Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Matías Melendez
- Centre Internationale de Recherche en Infectiologie, INSERM U1111, CNRS UMR5038, Ecole Normale Supérieure, Université Lyon 1, Lyon, France
| | - Virginia Vanasco
- Instituto de Bioquímica y Medicina Molecular, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Phil Barker
- Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Silvia Alvarez
- Instituto de Bioquímica y Medicina Molecular, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Alberto Epstein
- Centre Internationale de Recherche en Infectiologie, INSERM U1111, CNRS UMR5038, Ecole Normale Supérieure, Université Lyon 1, Lyon, France
| | - Diana Jerusalinsky
- Instituto de Biología Celular y Neurociencia “Prof. E. De Robertis”, Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Alberto Javier Ramos
- Instituto de Biología Celular y Neurociencia “Prof. E. De Robertis”, Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
- * E-mail:
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Smith CB, Walker K, Badawi N, Waters KA, MacLean JE. Impact of sleep and breathing in infancy on outcomes at three years of age for children with cleft lip and/or palate. Sleep 2014; 37:919-25. [PMID: 24790270 DOI: 10.5665/sleep.3660] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
STUDY OBJECTIVES To evaluate the relationship between sleep disordered breathing (SDB) in early infancy and outcomes at 3 years of age in children with cleft lip and/or palate (CL/P). DESIGN Observational follow-up study. SETTING Multidisciplinary CL/P clinic, tertiary centre. PARTICIPANTS Children with CL/P who participated in a study of sleep and breathing in infancy. MEASUREMENTS AND RESULTS The families of 52 children were approached for this follow-up study. The children underwent neurocognitive (Bayley Scales of Infant and Toddler Development, Third Edition; BSID-III), quality of life (Infant/Toddler Quality of Life Questionnaire; ITQOL), and growth assessments at 3 years. The families of 33 children (66%) completed follow-up at 36.7 ± 1.4 months. The apnea-hypopnea index (AHI) in infancy was 23.9 ± 18.0 events/h. Mean group BSID-III scores fell within the standardized normal range (10 ± 3) for all domains; however, language scores were lower than control children. Quality of life scores and growth parameter z-scores were similar to published control data. PSG variables in infancy showed significant relationships with outcomes at 3 years of age; lower percentage of AS/REM sleep was associated with lower cognition score; more obstructive events were associated with lower global behavior ITQOL score; and higher number of respiratory events in infancy was associated with lower weight z-score. CONCLUSION Neurocognition, quality of life, and growth measures from children with CL/P fall within a normal range; however, scores in the language domain are lower than controls. Sleep and respiratory elements of SDB in infancy appear to modify these outcomes at 3 years of age.
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Affiliation(s)
- Courtney B Smith
- Department of Respiratory Medicine, The Children's Hospital at Westmead, Westmead, NSW, Australia ; Medical Program, University of New South, Sydney, NSW, Australia
| | - Karen Walker
- Discipline of Paediatrics & Child Health, University of Sydney, Sydney, NSW, Australia ; Neonatal Intensive Care Unit, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Nadia Badawi
- Discipline of Paediatrics & Child Health, University of Sydney, Sydney, NSW, Australia ; Neonatal Intensive Care Unit, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Karen A Waters
- Discipline of Paediatrics & Child Health, University of Sydney, Sydney, NSW, Australia ; Department of Respiratory Medicine, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Joanna E MacLean
- Department of Pediatrics & The Women & Children's Research Institute, University of Alberta, Edmonton, AB, Canada ; Discipline of Paediatrics & Child Health, University of Sydney, Sydney, NSW, Australia ; Department of Respiratory Medicine, The Children's Hospital at Westmead, Westmead, NSW, Australia
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Daulatzai MA. Neurotoxic Saboteurs: Straws that Break the Hippo’s (Hippocampus) Back Drive Cognitive Impairment and Alzheimer’s Disease. Neurotox Res 2013; 24:407-59. [DOI: 10.1007/s12640-013-9407-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 06/06/2013] [Accepted: 06/17/2013] [Indexed: 12/29/2022]
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Death by a thousand cuts in Alzheimer's disease: hypoxia--the prodrome. Neurotox Res 2013; 24:216-43. [PMID: 23400634 DOI: 10.1007/s12640-013-9379-2] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 01/10/2013] [Accepted: 01/21/2013] [Indexed: 12/30/2022]
Abstract
A wide range of clinical consequences may be associated with obstructive sleep apnea (OSA) including systemic hypertension, cardiovascular disease, pulmonary hypertension, congestive heart failure, cerebrovascular disease, glucose intolerance, impotence, gastroesophageal reflux, and obesity, to name a few. Despite this, 82 % of men and 93 % of women with OSA remain undiagnosed. OSA affects many body systems, and induces major alterations in metabolic, autonomic, and cerebral functions. Typically, OSA is characterized by recurrent chronic intermittent hypoxia (CIH), hypercapnia, hypoventilation, sleep fragmentation, peripheral and central inflammation, cerebral hypoperfusion, and cerebral glucose hypometabolism. Upregulation of oxidative stress in OSA plays an important pathogenic role in the milieu of hypoxia-induced cerebral and cardiovascular dysfunctions. Strong evidence underscores that cerebral amyloidogenesis and tau phosphorylation--two cardinal features of Alzheimer's disease (AD), are triggered by hypoxia. Mice subjected to hypoxic conditions unambiguously demonstrated upregulation in cerebral amyloid plaque formation and tau phosphorylation, as well as memory deficit. Hypoxia triggers neuronal degeneration and axonal dysfunction in both cortex and brainstem. Consequently, neurocognitive impairment in apneic/hypoxic patients is attributable to a complex interplay between CIH and stimulation of several pathological trajectories. The framework presented here helps delineate the emergence and progression of cognitive decline, and may yield insight into AD neuropathogenesis. The global impact of CIH should provide a strong rationale for treating OSA and snoring clinically, in order to ameliorate neurocognitive impairment in aged/AD patients.
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Yang Q, Wang Y, Feng J, Cao J, Chen B. Intermittent hypoxia from obstructive sleep apnea may cause neuronal impairment and dysfunction in central nervous system: the potential roles played by microglia. Neuropsychiatr Dis Treat 2013; 9:1077-86. [PMID: 23950649 PMCID: PMC3742344 DOI: 10.2147/ndt.s49868] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Obstructive sleep apnea (OSA) is a common condition characterized by repetitive episodes of complete (apnea) or partial (hypopnea) obstruction of the upper airway during sleep, resulting in oxygen desaturation and arousal from sleep. Intermittent hypoxia (IH) resulting from OSA may cause structural neuron damage and dysfunction in the central nervous system (CNS). Clinically, it manifests as neurocognitive and behavioral deficits with oxidative stress and inflammatory impairment as its pathophysiological basis, which are mediated by microglia at the cellular level. Microglia are dominant proinflammatory cells in the CNS. They induce CNS oxidative stress and inflammation, mainly through mitochondria, reduced nicotinamide adenine dinucleotide phosphate oxidase, and the release of excitatory toxic neurotransmitters. The balance between neurotoxic versus protective and anti- versus proinflammatory microglial factors might determine the final roles of microglia after IH exposure from OSA. Microglia inflammatory impairments will continue and cascade persistently upon activation, ultimately resulting in clinically significant neuron damage and dysfunction in the CNS. In this review article, we summarize the mechanisms of structural neuron damage in the CNS and its concomitant dysfunction due to IH from OSA, and the potential roles played by microglia in this process.
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Affiliation(s)
- Qingchan Yang
- Graduate School of Tianjin Medical University, Tianjin, People's Republic of China
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Fung SJ, Xi M, Zhang J, Sampogna S, Chase MH. Apnea produces excitotoxic hippocampal synapses and neuronal apoptosis. Exp Neurol 2012; 238:107-13. [PMID: 22921462 DOI: 10.1016/j.expneurol.2012.08.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 07/27/2012] [Accepted: 08/03/2012] [Indexed: 12/20/2022]
Abstract
Obstructive sleep apnea (OSA) results in the degeneration of neurons in the hippocampus that eventuates in neurocognitive deficits. We were therefore interested in determining the effects of apnea on monosynaptic excitatory processes in a hippocampal pathway (cornu ammonis 3-cornu ammonis 1, CA3-CA1) that has been shown to mediate the processing of cognitive information. In addition, to substantiate an anatomical basis for the cognitive dysfunction that occurs in OSA patients, we examined the effects of apnea with respect to neurodegenerative changes (apoptosis) in the same hippocampal pathway. In order to determine the effects of apnea, an automated system for the generation and analysis of single and recurrent periods of apnea was developed. Utilizing this system, the field excitatory postsynaptic potential (fEPSP) generated by pyramidal neurons in the CA1 region of the hippocampus was monitored in α-chloralose anesthetized rats following stimulation of glutamatergic afferents in the CA3 region. A stimulus-response (input-output) curve for CA3-CA1 synaptic activity was determined. In addition, a paired-pulse paradigm was employed to evaluate, electrophysiologically, the presynaptic release of glutamate. Changes in the synaptic efficacy were assessed following single episodes of apnea induced by ventilatory arrest (60 to 80 s duration, mean=72 s; mean oxygen desaturation was 53% of normoxia level). Apnea resulted in a significant potentiation of the amplitude (mean=126%) and slope (mean=117%) of the baseline CA1 fEPSP. This increase in the fEPSP was accompanied by a significant decrease in the amplitude (71%) and slope (81%) of normalized paired-pulse facilitation (PPF) ratios. Since the potentiation of the fEPSP is inversely proportional to changes in PPF ratio, the potentiated fEPSP accompanied by the reduced PPF reveals that apnea produces an abnormal increase in the preterminal release of glutamate that results in the over-activation (and calcium overloading) of hippocampal CA1 neurons. Thus, we conclude that individual episodes of apnea result in the development of excitotoxic processes in the hippocampal CA3-CA1 pathway that is critically involved in the processing of cognitive information. Morphologically, the deleterious effect of recurrent apnea was substantiated by the finding of apoptosis in CA1 neurons of apneic (but not normoxic) animals.
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Affiliation(s)
- Simon J Fung
- VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA.
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28
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Quintessential Risk Factors: Their Role in Promoting Cognitive Dysfunction and Alzheimer’s Disease. Neurochem Res 2012; 37:2627-58. [DOI: 10.1007/s11064-012-0854-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 07/21/2012] [Indexed: 12/13/2022]
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29
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Lal C, Strange C, Bachman D. Neurocognitive Impairment in Obstructive Sleep Apnea. Chest 2012; 141:1601-1610. [DOI: 10.1378/chest.11-2214] [Citation(s) in RCA: 273] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Xie H, Yung WH. Chronic intermittent hypoxia-induced deficits in synaptic plasticity and neurocognitive functions: a role for brain-derived neurotrophic factor. Acta Pharmacol Sin 2012; 33:5-10. [PMID: 22212429 DOI: 10.1038/aps.2011.184] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Obstructive sleep apnea (OSA) is well known for its metabolic as well as neurobehavioral consequences. Chronic intermittent hypoxia (IH) is a major component of OSA. In recent years, substantial advances have been made in elucidating the cellular and molecular mechanisms underlying the effect of chronic IH on neurocognitive functions, many of which are based on studies in animal models. A number of hypotheses have been put forward to explain chronic IH-induced neurological dysfunctions. Among these, the roles of oxidative stress and apoptosis-related neural injury are widely accepted. Here, focusing on results derived from animal studies, we highlight a possible role of reduced expression of brain-derived neurotrophic factor (BDNF) in causing impairment in long-term synaptic plasticity and neurocognitive functions during chronic IH. The possible relationship between BDNF and previous findings on this subject will be elucidated.
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31
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Bruin PFCD, Bagnato MDC. [Cognitive impairment in obstructive sleep apnea syndrome]. J Bras Pneumol 2011; 36 Suppl 2:32-7. [PMID: 20944979 DOI: 10.1590/s1806-37132010001400010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cognitive and performance impairment is well established in patients with obstructive sleep apnea syndrome (OSAS), having a significant impact on the quality of life and the risk of accidents in these individuals. The severity of the impairment correlates with that of the OSAS, which explains the apparent discrepancy between studies using patients from sleep clinics and population-based studies in terms of the reported frequency and severity of such impairment. Cognitive processing, sustained attention, executive functioning, and memory have all been reported to be impaired in OSAS. However, the causal mechanisms of these deficits have not been entirely clarified, and the relative contribution of intermittent hypoxia and sleep disruption in OSAS is particularly controversial. The potential effect of daytime sleepiness on the performance of these patients on various cognitive tests has yet to be determined, as does that of common comorbidities, such as diabetes, systemic arterial hypertension, cardiovascular disease, and obesity. There is compelling evidence that CPAP treatment can improve performance and cognition, particularly in mild to moderate cases, although further studies on the long-term impact of this type of treatment are still needed.
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32
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Fung SJ, Xi M, Zhang J, Torterolo P, Sampogna S, Morales FR, Chase MH. Projection neurons from the central nucleus of the amygdala to the nucleus pontis oralis. J Neurosci Res 2010; 89:429-36. [PMID: 21259329 DOI: 10.1002/jnr.22554] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 10/14/2010] [Accepted: 10/19/2010] [Indexed: 12/19/2022]
Abstract
The present retrograde labeling study was designed to determine the presence and pattern of projections from individual subdivisions of the central nucleus of the amygdala (CNA) to the nucleus pontis oralis (NPO), which is a critical brainstem site involved in the generation and maintenance of active (REM) sleep. Projections from the CNA were labeled with the retrograde tracer cholera toxin B-subunit (CTB), which was injected, unilaterally, via microiontophoresis, into the NPO. Sections of the amygdala were immunostained in order to identify CTB-labeled CNA neurons and CNA neurons that contained CTB plus the vesicular glutamate transporter 2 (VGLUT2), which is a marker for glutamatergic neurons. Histological analyses revealed that retrogradely labeled neurons that project to the NPO were localized, ipsilaterally, within the medial, lateral, and capsular subdivisions of the CNA. In addition, a substantial proportion (24%) of all retrogradely labeled CNA neurons also exhibited VGLUT2 immunoreactivity. The present study demonstrates that glutamatergic neurons, which are present within various subdivisions of the CNA, project directly to the NPO. These data lend credence to the hypothesis that NPO neurons that are involved in the control of active sleep are activated by glutamatergic projections from the amygdala.
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Affiliation(s)
- Simon J Fung
- VA Greater Los Angeles Healthcare System, Los Angeles, California, USA.
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Zhang JH, Fung SJ, Xi M, Sampogna S, Chase MH. Prevention of apnea-induced apoptosis in NREM- and REM-generating nuclei of adult guinea pigs. Brain Res 2010; 1347:161-9. [PMID: 20515665 DOI: 10.1016/j.brainres.2010.05.078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Revised: 05/23/2010] [Accepted: 05/25/2010] [Indexed: 12/31/2022]
Abstract
The present study was designed to investigate the effects of recurrent periods of apnea/hypoxia on the morphology of neurons in sites that control NREM and REM sleep. In addition, we determined whether the administration of a GABA agonist, eszopiclone, was capable of preventing the degenerative, i.e., apoptotic, sequelae of hypoxia in these sleep-promoting neurons. Adult guinea pigs were divided into control (normoxic) and hypoxic groups; a separate group of hypoxic animals was administered eszopiclone. Recurrent periods of hypoxia and normoxia lasted for a duration of 3h. Subsequently, the brains were sectioned, and areas in the CNS that control NREM sleep as well as REM sleep were examined after staining with an antibody raised against single-stranded DNA, which labels apoptotic neurons. In the group of control (normoxic) animals, apoptotic neurons were not observed in CNS regions that control NREM or REM sleep. In hypoxic animals, a large number of apoptotic neurons were found in the preceding regions. In the hypoxic animals that were administered eszopiclone, there were almost no apoptotic neurons in the brain regions that control NREM or REM sleep. These results demonstrate that recurrent periods of apnea induce extensive apoptosis in CNS nuclei that control NREM and REM sleep and that eszopiclone is capable of preventing neuronal degeneration in these sites. We suggest that the degeneration of neurons in sites that control the states of sleep is responsible for those sleep disturbances that arise as a consequence of hypoxia in individuals with sleep-related breathing disorders.
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Affiliation(s)
- Jian-Hua Zhang
- WebSciences International, 1251 Westwood Blvd., Los Angeles, CA 90024, USA.
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Zhang JH, Fung SJ, Xi M, Sampogna S, Chase MH. Apnea produces neuronal degeneration in the pons and medulla of guinea pigs. Neurobiol Dis 2010; 40:251-64. [PMID: 20554036 DOI: 10.1016/j.nbd.2010.05.032] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Revised: 05/19/2010] [Accepted: 05/30/2010] [Indexed: 12/18/2022] Open
Abstract
Obstructive sleep apnea and other sleep-related breathing disorders result in recurrent periods of oxygen deprivation (hypoxia), hypercapnia and an increase in the cellular production of reactive oxygen species (oxidative stress-related injury). Individuals with these disorders suffer from a variety of cellular abnormalities that result in cardiopulmonary dysfunctions, disturbances in sleep and other pathologies. In the present experiment, using an animal model of sleep apnea, we determined that the degeneration of neurons and glia, due to apoptosis, occurs in specific regions of the pons and medulla. Adult guinea pigs, which were divided into control (normoxic) and experimental (hypoxic) groups, were anesthetized with alpha-chloralose and immobilized with Flaxedil. Apnea (hypoxia) was induced by ventilatory arrest in order to desaturate the oxyhemoglobin to 75% SpO(2). A sequence of apnea, followed by ventilation with recovery to >95% SpO(2), was repeated for a period of 3h. At the end of the period of recurrent apnea, the animals were perfused and brain sections were immunostained with a mouse monoclonal antibody raised against single-stranded DNA (ssDNA). Apoptotic neurons and glia, which were not found in the control group of animals, were present in brainstem regions in hypoxic group of animals; these regions involved in the control of respiration (e.g., the parafacial respiratory group and the ventral respiratory group), cardiovascular functions (e.g., the nucleus ambiguus, the nucleus tractus solitarius and the dorsal motor nucleus of the vagus) as well as REM sleep (the nucleus pontis oralis) and wakefulness (e.g., the dorsal raphe and locus ceruleus). We suggest apoptotic neurons and glia in critical areas of the pons and medulla results in many of the comorbidities experienced by patients with sleep-disordered breathing pathologies.
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Xie H, Leung KL, Chen L, Chan YS, Ng PC, Fok TF, Wing YK, Ke Y, Li AM, Yung WH. Brain-derived neurotrophic factor rescues and prevents chronic intermittent hypoxia-induced impairment of hippocampal long-term synaptic plasticity. Neurobiol Dis 2010; 40:155-62. [PMID: 20553872 DOI: 10.1016/j.nbd.2010.05.020] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Revised: 05/11/2010] [Accepted: 05/17/2010] [Indexed: 01/24/2023] Open
Abstract
Obstructive sleep apnea (OSA) is a common sleep and breathing disorder characterized by repeated episodes of hypoxemia. OSA causes neurocognitive deficits including perception and memory impairment but the underlying mechanisms are unknown. Here we show that in a mouse model of OSA, chronic intermittent hypoxia treatment impairs both early- and late-phase long-term potentiation (LTP) in the hippocampus. In intermittent hypoxia-treated mice the excitability of CA1 neurons was reduced and hippocampal brain-derived neurotrophic factor (BDNF) was down-regulated. We further showed that exogenous application of BDNF restored the magnitude of LTP in hippocampal slices from hypoxia-treated mice. In addition, microinjection of BDNF into the brain of the hypoxic mice prevented the impairment in LTP. These data suggest that intermittent hypoxia impairs hippocampal neuronal excitability and reduces the expression of BDNF leading to deficits in LTP and memory formation. Thus, BDNF level may be a novel therapeutic target for alleviating OSA-induced neurocognitive deficits.
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Affiliation(s)
- Hui Xie
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China
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Fung SJ, Xi MC, Zhang JH, Yamuy J, Sampogna S, Tsai KL, Lim V, Morales FR, Chase MH. Eszopiclone prevents excitotoxicity and neurodegeneration in the hippocampus induced by experimental apnea. Sleep 2010; 32:1593-601. [PMID: 20041595 DOI: 10.1093/sleep/32.12.1593] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
STUDY OBJECTIVE This study was designed to determine the effects of eszopiclone on apnea-induced excitotoxic synaptic processes and apoptosis in the hippocampus. DESIGN Recurrent periods of apnea, which consisted of a sequence of apnea (75% SpO2), followed by ventilation with recovery to normoxia (> 95% SpO2), were induced for a period of three hours in anesthetized guinea pigs. The CA3 Schaffer collateral pathway in the hippocampus was stimulated and the field excitatory postsynaptic potential (fEPSP) response was recorded in CA1. Animals in the experimental group received an intravenous injection of eszopiclone (3 mg/kg) 10 min prior to the initiation of the periods of recurrent apnea, and once every 60 min thereafter; control animals received comparable injections of vehicle. At the end of the 3-h period of recurrent apnea, the animals were perfused, and hippocampal sections were immunostained in order to determine the presence of apoptosis, i.e., programmed cell death. ANALYSES AND RESULTS: Apnea resulted in a persistent increase in synaptic responsiveness of CA1 neurons as determined by analyses of the fEPSP. Eszopiclone antagonized the apnea-induced increase in the fEPSP. Morphological analyses revealed significant apoptosis of CA1 neurons in control animals; however, there was no significant apoptosis in eszopiclone-treated animals. CONCLUSIONS Eszopiclone was determined to suppress the apnea-induced hyperexcitability of hippocampal CA1 neurons, thereby reducing/eliminating neurotoxicity. These data lend credence to our hypothesis that eszopiclone, exclusive of its hypnotic actions, has the capacity to function as a potent neuroprotective agent.
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Affiliation(s)
- Simon J Fung
- WebSciences International, 1251 Westwood Blvd., Los Angeles, CA 90024, USA.
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Aviles-Reyes RX, Angelo MF, Villarreal A, Rios H, Lazarowski A, Ramos AJ. Intermittent hypoxia during sleep induces reactive gliosis and limited neuronal death in rats: implications for sleep apnea. J Neurochem 2010; 112:854-69. [DOI: 10.1111/j.1471-4159.2009.06535.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Henley DE, Russell GM, Douthwaite JA, Wood SA, Buchanan F, Gibson R, Woltersdorf WW, Catterall JR, Lightman SL. Hypothalamic-pituitary-adrenal axis activation in obstructive sleep apnea: the effect of continuous positive airway pressure therapy. J Clin Endocrinol Metab 2009; 94:4234-42. [PMID: 19820009 DOI: 10.1210/jc.2009-1174] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
CONTEXT Obstructive sleep apnea (OSA) is a common condition with significant cardiovascular and metabolic comorbidity. We hypothesized that these may result from OSA-induced perturbations of endogenous ultradian hypothalamic-pituitary-adrenal axis activity. OBJECTIVE The aim of the study was to investigate ACTH and cortisol ultradian patterns using an automated, repetitive blood sampling technique. DESIGN Samples for ACTH and cortisol were collected from 10 patients with moderate to severe OSA under basal conditions, at 10-min intervals over 24 h, at diagnosis and 3 months after compliant continuous positive airway pressure (CPAP) therapy. Multiple-parameter deconvolution estimated specific measures of ACTH and cortisol pulsatile secretion from blood hormone concentrations. RESULTS Mean total ACTH and cortisol production were elevated pre-CPAP compared to post-CPAP (ACTH, 1459.8 +/- 123.0 vs. 808.1 +/- 97.9 pg/ml, P < 0.001; cortisol, 5748.9 +/- 364.9 vs. 3817.7 +/- 351.7 nmol/liter, P < 0.001) as were mean total pulsatile production (ACTH, 764.1 +/- 86.3 vs. 383.5 +/- 50.0 pg/ml, P = 0.002; cortisol, 4715.9 +/- 253.3 vs. 3227.7 +/- 258.8 nmol/liter, P < 0.001). ACTH and cortisol secretory burst mean half-duration were higher at diagnosis (12.3 +/- 0.7 and 13.5 +/- 0.7 vs. 7.8 +/- 0.4 and 8.4 +/- 0.6 min, respectively, P < 0.001); thus, 95% of each ACTH secretion occurred in 21.0 +/- 1.2 vs. 12.9 +/- 0.8 min post-CPAP (P < 0.001) and for cortisol in 23.0 +/- 1.2 vs. 14.2 +/- 1.1 min post-CPAP (P < 0.001). Approximate entropy (ApEn) revealed greater disorderliness in both ACTH (P = 0.03) and cortisol (P = 0.001) time series pre-CPAP. Forward and reverse cross-ApEn suggested nodal disruption at central and adrenal levels pre-CPAP (P = 0.01). Significantly elevated cortisol responses to a single breath of 35% CO(2) occurred pre-CPAP (P = 0.006). CONCLUSIONS Untreated compared to treated OSA is associated with marked disturbances in ACTH and cortisol secretory dynamics, resulting in prolonged tissue exposure to disordered, elevated hormone levels.
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Affiliation(s)
- David E Henley
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, University of Bristol, Bristol BS1 3NY, United Kingdom.
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Zhang JH, Fung SJ, Xi M, Sampogna S, Chase MH. Recurrent apnea induces neuronal apoptosis in the guinea pig forebrain. Exp Neurol 2008; 216:290-4. [PMID: 19124019 DOI: 10.1016/j.expneurol.2008.12.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Accepted: 12/01/2008] [Indexed: 11/29/2022]
Abstract
Obstructive sleep apnea (OSA) and sleep-disordered breathing (SDB) can result in impaired cognition and mental acuity, and the generation of mood disorders, including depression. However, the mechanisms of neuronal damage for these complications have not been elucidated. Accordingly, using immunohistochemical technique with monoclonal antibody against single-stranded DNA, we examined the morphological effects of chronic recurrent apnea on neurons in the hippocampus and related forebrain sites in guinea pigs. Our results show that a large number of neurons labeled by anti-ssDNA antibody were present in the cingulate, insular and frontal cortices, the hippocampus and the amygdala in conjunction with periods of recurrent apnea. However, no labeling was observed in comparable regions of the brain in control guinea pigs. In the cortices of experimental animals, labeled neurons were detected mainly in the superficial layers (II-III) in the frontal, insular and cingulate cortex. In the hippocampus, most labeled neurons were located in the CA1 region, in which most of stained neurons were observed in strata pyramidal, while only a few positive neurons were located in the strata radiatum and the strata oriens. In addition, a large number of labeled neurons were also detected in the central nucleus of amygdala in the guinea pigs underwent recurrent periods of apnea. The present data indicate that recurrent apnea results in cell death in the hippocampus and related forebrain regions via mechanisms of apoptosis, which may represent the basis for the clinical complications of obstructive sleep apnea and sleep-disordered breathing.
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Abstract
PURPOSE OF REVIEW Obstructive sleep apnea (OSA) is a prevalent disorder with clinically well known mid-term and long-term consequences. It is difficult, however, to investigate the mechanisms causing morbidity in OSA from human studies, owing to confounding factors in patients. Animal research is useful to analyze the various injurious stimuli--intermittent hypoxia/hypercapnia, mechanical stress and sleep disruption--that potentially cause OSA morbidity. This review is focused on the most recent advances in our understanding of the consequences of OSA, achieved as a result of animal models. RECENT FINDINGS Animal research has improved our knowledge of various aspects of the cardiovascular consequences of OSA: myocardial damage, left ventricular dysfunction, vasoconstriction, hypertension and atherosclerosis. The systemic and metabolic consequences of OSA--inflammation, insulin resistance, alterations in lipid metabolism and hepatic morbidity--have also been investigated with animal models. Our understanding of the mechanisms involved in the neurocognitive consequences of OSA--neuronal and brain alterations and cognitive dysfunctions--has also been improved through animal research. Moreover, animal models have recently been used to investigate the mechanisms of upper airway inflammation and dysfunction. SUMMARY The simple experimental models used to investigate OSA morbidity are useful for investigating isolated mechanisms. However, more complex and realistic models incorporating the various injurious challenges characterizing OSA are required to more precisely translate the results of animal research to patients and to design potentially preventive and therapeutic strategies.
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