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Proceedings of the First Pediatric Coma and Disorders of Consciousness Symposium by the Curing Coma Campaign, Pediatric Neurocritical Care Research Group, and NINDS: Gearing for Success in Coma Advancements for Children and Neonates. Neurocrit Care 2023; 38:447-469. [PMID: 36759418 PMCID: PMC9910782 DOI: 10.1007/s12028-023-01673-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 01/03/2023] [Indexed: 02/11/2023]
Abstract
This proceedings article presents the scope of pediatric coma and disorders of consciousness based on presentations and discussions at the First Pediatric Disorders of Consciousness Care and Research symposium held on September 14th, 2021. Herein we review the current state of pediatric coma care and research opportunities as well as shared experiences from seasoned researchers and clinicians. Salient current challenges and opportunities in pediatric and neonatal coma care and research were identified through the contributions of the presenters, who were Jose I. Suarez, MD, Nina F. Schor, MD, PhD, Beth S. Slomine, PhD Erika Molteni, PhD, and Jan-Marino Ramirez, PhD, and moderated by Varina L. Boerwinkle, MD, with overview by Mark Wainwright, MD, and subsequent audience discussion. The program, executively planned by Varina L. Boerwinkle, MD, Mark Wainwright, MD, and Michelle Elena Schober, MD, drove the identification and development of priorities for the pediatric neurocritical care community.
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Huang Q, Qiao Lv, Jiang L, Chen Q, Zhang K. Recent progress of biocompatible carbon dots in hypoxia-related fields. J Biomater Appl 2023; 37:1159-1168. [PMID: 36083209 DOI: 10.1177/08853282221125313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Almost all eukaryotes need oxygen to maintain regular physiological activities. When the organism is under hypoxic situation for a persistent or periodic, it will induce irreversible physiological disorders and even pathological results. Hypoxia is closely related to the pathogenesis of metabolic diseases, cancer, chronic heart disease and kidney disease, myocardial ischemia, as well as reproductive diseases like preeclampsia and endometriosis. Therefore, monitoring and treatment of hypoxia have important implications for the pathophysiology of human-related diseases. Carbon dots (CDs) are emerging nanomaterials developed after 2004 with excellent performance, and have broad application potential in variousdomains likeoptical, biomedicine, energy. Advanced hypoxia therapeutics should be integrated with monitoring and treatment, and CDs with excellent performance are good potential options when sensing is combined with various therapeutic methods. Some researchers have also begun to carry out research in related fields and achieved some results. This article aims to clarify the various applications of CDs in hypoxia-related fields in recent years, including hypoxia sensing and hypoxia tumor theranostics. Finally, the possible challenges and prospects for the application of CDs in hypoxia-related fields are discussed.
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Affiliation(s)
- Qing Huang
- Clinical Medicine Research Center, Xinqiao Hospital, 12525Army Medical UniversityThird Military Medical University, Chongqing, China
| | - Qiao Lv
- Clinical Medicine Research Center, Xinqiao Hospital, 12525Army Medical UniversityThird Military Medical University, Chongqing, China
| | - Lu Jiang
- Clinical Medicine Research Center, Xinqiao Hospital, 12525Army Medical UniversityThird Military Medical University, Chongqing, China
| | - Qian Chen
- Clinical Medicine Research Center, Xinqiao Hospital, 12525Army Medical UniversityThird Military Medical University, Chongqing, China
| | - Kebin Zhang
- Clinical Medicine Research Center, Xinqiao Hospital, 12525Army Medical UniversityThird Military Medical University, Chongqing, China
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Cardiovascular autonomic control under obstructive sleep apnea combined with atrial fibrillation: Its role in pathogenesis and therapy. COR ET VASA 2022. [DOI: 10.33678/cor.2022.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Gonzalez-Rothi EJ, Tadjalli A, Allen LL, Ciesla MC, Chami ME, Mitchell GS. Protocol-Specific Effects of Intermittent Hypoxia Pre-Conditioning on Phrenic Motor Plasticity in Rats with Chronic Cervical Spinal Cord Injury. J Neurotrauma 2021; 38:1292-1305. [PMID: 33446048 PMCID: PMC8182475 DOI: 10.1089/neu.2020.7324] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
"Low-dose" acute intermittent hypoxia (AIH; 3-15 episodes/day) is emerging as a promising therapeutic strategy to improve motor function after incomplete cervical spinal cord injury (cSCI). Conversely, chronic "high-dose" intermittent hypoxia (CIH; > 80-100 episodes/day) elicits multi-system pathology and is a hallmark of sleep apnea, a condition highly prevalent in individuals with cSCI. Whereas daily AIH (dAIH) enhances phrenic motor plasticity in intact rats, it is abolished by CIH. However, there have been no direct comparisons of prolonged dAIH versus CIH on phrenic motor outcomes after chronic cSCI. Thus, phrenic nerve activity and AIH-induced phrenic long-term facilitation (pLTF) were assessed in anesthetized rats. Experimental groups included: 1) intact rats exposed to 28 days of normoxia (Nx28; 21% O2; 8 h/day), and three groups with chronic C2 hemisection (C2Hx) exposed to either: 2) Nx28; 3) dAIH (dAIH28; 10, 5-min episodes of 10.5% O2/day; 5-min intervals); or 4) CIH (IH28-2/2; 2-min episodes; 2-min intervals; 8 h/day). Baseline ipsilateral phrenic nerve activity was reduced in injured versus intact rats but unaffected by dAIH28 or IH28-2/2. There were no group differences in contralateral phrenic activity. pLTF was enhanced bilaterally by dAIH28 versus Nx28 but unaffected by IH28-2/2. Whereas dAIH28 enhanced pLTF after cSCI, it did not improve baseline phrenic output. In contrast, unlike shorter protocols in intact rats, CIH28-2/2 did not abolish pLTF in chronic C2Hx. Mechanisms of differential responses to dAIH versus CIH are not yet known, particularly in the context of cSCI. Further, it remains unclear whether enhanced phrenic motor plasticity can improve breathing after cSCI.
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Affiliation(s)
| | - Arash Tadjalli
- Department of Physical Therapy, University of Florida, Gainesville, Florida, USA
| | - Latoya L. Allen
- Department of Physical Therapy, University of Florida, Gainesville, Florida, USA
| | - Marissa C. Ciesla
- Department of Physical Therapy, University of Florida, Gainesville, Florida, USA
| | - Mohamad El Chami
- Department of Physical Therapy, University of Florida, Gainesville, Florida, USA
| | - Gordon S. Mitchell
- Department of Physical Therapy, University of Florida, Gainesville, Florida, USA
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Dissanayake HU, Bin YS, Ucak S, de Chazal P, Sutherland K, Cistulli PA. Association between autonomic function and obstructive sleep apnea: A systematic review. Sleep Med Rev 2021; 57:101470. [PMID: 33839505 DOI: 10.1016/j.smrv.2021.101470] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/31/2021] [Accepted: 02/14/2021] [Indexed: 12/18/2022]
Abstract
Obstructive sleep apnea (OSA) is an independent risk factor for hypertension and cardiovascular disease. Effects of OSA on the autonomic nervous system may mediate this association. We performed a systematic literature review to determine the profile of autonomic function associated with OSA. Three electronic databases were searched for studies of OSA patients aged ≥18 years in which autonomic function was assessed. Studies comparing patients with and without OSA, or examining the association of OSA severity with changes in autonomic function were included. Seventy-one studies met the inclusion criteria and autonomic function has been assessed using a range of techniques. The profile of autonomic function found in OSA include increased sympathetic activity, reduced parasympathetic activity and less consistently found low heart rate variability. Altered autonomic function in OSA may explain the pathophysiology of increased cardiovascular risk. Evidence from intervention studies is required to determine if treatment improves autonomic function associated with OSA.
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Affiliation(s)
- Hasthi U Dissanayake
- Sleep Research Group, Charles Perkins Centre, The University of Sydney, Australia; Northern Clinical School, Faculty of Medicine and Health, The University of Sydney, Australia.
| | - Yu S Bin
- Sleep Research Group, Charles Perkins Centre, The University of Sydney, Australia; Northern Clinical School, Faculty of Medicine and Health, The University of Sydney, Australia
| | - Seren Ucak
- Sleep Research Group, Charles Perkins Centre, The University of Sydney, Australia; Northern Clinical School, Faculty of Medicine and Health, The University of Sydney, Australia
| | - Philip de Chazal
- Sleep Research Group, Charles Perkins Centre, The University of Sydney, Australia; School of Biomedical Engineering, University of Sydney, Sydney, NSW, 2006, Australia
| | - Kate Sutherland
- Sleep Research Group, Charles Perkins Centre, The University of Sydney, Australia; Northern Clinical School, Faculty of Medicine and Health, The University of Sydney, Australia; Centre for Sleep Health & Research, Department of Respiratory Medicine, Royal North Shore Hospital, Australia
| | - Peter A Cistulli
- Sleep Research Group, Charles Perkins Centre, The University of Sydney, Australia; Northern Clinical School, Faculty of Medicine and Health, The University of Sydney, Australia; Centre for Sleep Health & Research, Department of Respiratory Medicine, Royal North Shore Hospital, Australia
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Dyavanapalli J. Novel approaches to restore parasympathetic activity to the heart in cardiorespiratory diseases. Am J Physiol Heart Circ Physiol 2020; 319:H1153-H1161. [PMID: 33035444 DOI: 10.1152/ajpheart.00398.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Neural control of the heart is regulated by sympathetic and parasympathetic divisions of the autonomic nervous system, both opposing each other to maintain cardiac homeostasis via regulating heart rate, conduction velocity, force of contraction, and coronary blood flow. Sympathetic hyperactivity and diminished parasympathetic activity are the characteristic features of many cardiovascular disease states including hypertension, myocardial ischemia, and arrhythmias that result in heart failure. Restoring parasympathetic activity to the heart has recently been identified as the promising approach to treat such conditions. However, approaches that used vagal nerve stimulation have been shown to be unsuccessful in heart failure. This review focuses on novel chemogenetic approaches used to identify the cardioprotective nature of activating neural points along the vagal pathway (both central and peripheral) while being selectively therapeutic in heart failure and obstructive sleep apnea.
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Affiliation(s)
- Jhansi Dyavanapalli
- Department of Pharmacology and Physiology, George Washington University, Washington, District of Columbia
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Littlejohn EL, Fedorchak S, Boychuk CR. Sex-steroid-dependent plasticity of brain-stem autonomic circuits. Am J Physiol Regul Integr Comp Physiol 2020; 319:R60-R68. [PMID: 32493037 DOI: 10.1152/ajpregu.00357.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
In the central nervous system (CNS), nuclei of the brain stem play a critical role in the integration of peripheral sensory information and the regulation of autonomic output in mammalian physiology. The nucleus tractus solitarius of the brain stem acts as a relay center that receives peripheral sensory input from vagal afferents of the nodose ganglia, integrates information from within the brain stem and higher central centers, and then transmits autonomic efferent output through downstream premotor nuclei, such as the nucleus ambiguus, the dorsal motor nucleus of the vagus, and the rostral ventral lateral medulla. Although there is mounting evidence that sex and sex hormones modulate autonomic physiology at the level of the CNS, the mechanisms and neurocircuitry involved in producing these functional consequences are poorly understood. Of particular interest in this review is the role of estrogen, progesterone, and 5α-reductase-dependent neurosteroid metabolites of progesterone (e.g., allopregnanolone) in the modulation of neurotransmission within brain-stem autonomic neurocircuits. This review will discuss our understanding of the actions and mechanisms of estrogen, progesterone, and neurosteroids at the cellular level of brain-stem nuclei. Understanding the complex interaction between sex hormones and neural signaling plasticity of the autonomic nervous system is essential to elucidating the role of sex in overall physiology and disease.
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Affiliation(s)
- Erica L Littlejohn
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health San Antonio, San Antonio, Texas
| | - Stephanie Fedorchak
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health San Antonio, San Antonio, Texas
| | - Carie R Boychuk
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health San Antonio, San Antonio, Texas
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Huang B, Liu H, Scherlag BJ, Sun L, Xing S, Xu J, Luo M, Guo Y, Cao G, Jiang H. Atrial fibrillation in obstructive sleep apnea: Neural mechanisms and emerging therapies. Trends Cardiovasc Med 2020; 31:127-132. [PMID: 32008837 DOI: 10.1016/j.tcm.2020.01.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 12/23/2019] [Accepted: 01/15/2020] [Indexed: 02/07/2023]
Abstract
Obstructive sleep apnea (OSA) has been reproducibly identified as a risk factor for initiation and progression of atrial fibrillation (AF) and reduces the efficacy of antiarrhythmic drugs, electrical cardioversion, and catheter ablation in AF. It is still controversial whether continuous positive airway pressure ventilation (CPAP) could improve the successful rate of AF treatment in OSA patients. Besides, CPAP has shown relative low compliance in patients with OSA. Therefore, novel optional therapies might be needed to improve the control of AF associated with OSA. A growing body of evidence suggests that autonomic activation contributes to the pathogenesis of AF in OSA. Acute apneic episodes result in sympathovagal co-activation, shortening atrial refractoriness and promoting the initiation of AF. Chronic OSA-induced sympathetic activation plays a crucial role in atrial autonomic, structural, and electrical remodeling, thus providing substrates for AF maintenance and recurrence. Therefore, the autonomic nervous system may be a promising therapeutic target for OSA and AF. Autonomic modulation as a treatment for OSA-associated AF has been well established in several preclinical studies. Further clinical studies are needed to provide a more precise definition of the role of autonomic modulation in the treatment of AF in OSA.
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Affiliation(s)
- Bing Huang
- Department of Cardiology, Renmin Hospital of Wuhan University, No. 238 Jiefang Road, Wuchang District, Wuhan, Hubei 430060, PR China; Department of Cardiology, Fifth Affiliated Hospital of Xinjiang Medical University, No. 118 Henan Road, Xinshi District, Urumqi, Xinjiang 830000, PR China; Cardiovascular Research Institute, Wuhan University, Wuhan, Hubei, PR China; Hubei Key Laboratory of Cardiology, Wuhan, Hubei, PR China
| | - Huafen Liu
- Department of Cardiology, Renmin Hospital of Wuhan University, No. 238 Jiefang Road, Wuchang District, Wuhan, Hubei 430060, PR China; Cardiovascular Research Institute, Wuhan University, Wuhan, Hubei, PR China; Hubei Key Laboratory of Cardiology, Wuhan, Hubei, PR China
| | - Benjamin J Scherlag
- Heart Rhythm Institute and Department of Medicine, University of Oklahoma Health Science Center, Oklahoma City, OK, United States
| | - Lihua Sun
- Department of Cardiology, Fifth Affiliated Hospital of Xinjiang Medical University, No. 118 Henan Road, Xinshi District, Urumqi, Xinjiang 830000, PR China
| | - Shifeng Xing
- Department of Cardiology, Fifth Affiliated Hospital of Xinjiang Medical University, No. 118 Henan Road, Xinshi District, Urumqi, Xinjiang 830000, PR China
| | - Jie Xu
- Department of Cardiology, Fifth Affiliated Hospital of Xinjiang Medical University, No. 118 Henan Road, Xinshi District, Urumqi, Xinjiang 830000, PR China
| | - Mei Luo
- Department of Cardiology, Fifth Affiliated Hospital of Xinjiang Medical University, No. 118 Henan Road, Xinshi District, Urumqi, Xinjiang 830000, PR China
| | - Yankai Guo
- Department of Cardiology, Fifth Affiliated Hospital of Xinjiang Medical University, No. 118 Henan Road, Xinshi District, Urumqi, Xinjiang 830000, PR China
| | - Guiqiu Cao
- Department of Cardiology, Fifth Affiliated Hospital of Xinjiang Medical University, No. 118 Henan Road, Xinshi District, Urumqi, Xinjiang 830000, PR China.
| | - Hong Jiang
- Department of Cardiology, Renmin Hospital of Wuhan University, No. 238 Jiefang Road, Wuchang District, Wuhan, Hubei 430060, PR China; Cardiovascular Research Institute, Wuhan University, Wuhan, Hubei, PR China; Hubei Key Laboratory of Cardiology, Wuhan, Hubei, PR China.
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9
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Littlejohn EL, Espinoza L, Lopez MM, Smith BN, Boychuk CR. GABA A receptor currents in the dorsal motor nucleus of the vagus in females: influence of ovarian cycle and 5α-reductase inhibition. J Neurophysiol 2019; 122:2130-2141. [PMID: 31596653 PMCID: PMC6879959 DOI: 10.1152/jn.00039.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 09/23/2019] [Accepted: 10/07/2019] [Indexed: 11/22/2022] Open
Abstract
The dorsal motor nucleus of the vagus (DMV) contains the preganglionic motor neurons important in the regulation of glucose homeostasis and gastrointestinal function. Despite the role of sex in the regulation of these processes, few studies examine the role of sex and/or ovarian cycle in the regulation of synaptic neurotransmission to the DMV. Since GABAergic neurotransmission is critical to normal DMV function, the present study used in vitro whole cell patch-clamping to investigate whether sex differences exist in GABAergic neurotransmission to DMV neurons. It additionally investigated whether the ovarian cycle plays a role in those sex differences. The frequency of phasic GABAA receptor-mediated inhibitory postsynaptic currents in DMV neurons from females was lower compared with males, and this effect was TTX sensitive and abolished by ovariectomy (OVX). Amplitudes of GABAergic currents (both phasic and tonic) were not different. However, females demonstrated significantly more variability in the amplitude of both phasic and tonic GABAA receptor currents. This difference was eliminated by OVX in females, suggesting that these differences were related to reproductive hormone levels. This was confirmed for GABAergic tonic currents by comparing females in two ovarian stages, estrus versus diestrus. Female mice in diestrus had larger tonic current amplitudes compared with those in estrus, and this increase was abolished after administration of a 5α-reductase inhibitor but not modulation of estrogen. Taken together, these findings demonstrate that DMV neurons undergo GABAA receptor activity plasticity as a function of sex and/or sex steroids.NEW & NOTEWORTHY Results show that GABAergic signaling in dorsal vagal motor neurons (DMV) demonstrates sex differences and fluctuates across the ovarian cycle in females. These findings are the first to demonstrate that female GABAA receptor activity in this brain region is modulated by 5α-reductase-dependent hormones. Since DMV activity is critical to both glucose and gastrointestinal homeostasis, these results suggest that sex hormones, including those synthesized by 5α-reductase, contribute to visceral, autonomic function related to these physiological processes.
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Affiliation(s)
- Erica L Littlejohn
- Department of Cellular and Integrative Physiology, College of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Liliana Espinoza
- Department of Cellular and Integrative Physiology, College of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Monica M Lopez
- Department of Cellular and Integrative Physiology, College of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Bret N Smith
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky
- Department of Neuroscience, College of Medicine, University of Kentucky, Lexington, Kentucky
| | - Carie R Boychuk
- Department of Cellular and Integrative Physiology, College of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
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Long-term stimulation of cardiac vagal preganglionic neurons reduces blood pressure in the spontaneously hypertensive rat. J Hypertens 2019; 36:2444-2452. [PMID: 30045362 DOI: 10.1097/hjh.0000000000001871] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Arterial hypertension is associated with autonomic nervous system dysfunction. Different interventional strategies have been implemented in recent years for the reduction of sympathetic activity in patients with hypertension. However, the therapeutic benefit of increasing vagal tone in hypertensive patients remains largely unexplored. OBJECTIVE Here, we describe the effects of long-term activation of vagal neural pathways on arterial pressure, heart rate arterial pressure variability and spontaneous baroreflex sensitivity in spontaneously hypertensive rats (SHR) and normotensive Wistar rats. METHODS Brainstem vagal preganglionic neurons residing in the dorsal vagal motor nucleus (DVMN) were targeted with a lentiviral vector to induce the expression of an artificial G(s) protein-coupled receptor termed designer receptors exclusively activated by designer drugs (DREADD-Gs). The transduced neurons were activated daily by systemic administration of otherwise inert ligand clozapine-n-oxide. Arterial pressure measurements were recorded in conscious freely moving animals after 21 consecutive days of DVMN stimulation. RESULTS Resting arterial pressure was significantly lower in SHRs expressing DREADD-Gs in the DVMN, compared with control SHRs expressing enhanced green fluorescent protein. No changes in arterial pressure were detected in Wistar rats expressing DREADD-Gs compared with rats expressing enhanced green fluorescent protein in the DVMN. Pharmacogenetic activation of DREADD-Gs-expressing DVMN neurons in SHRs was accompanied with increased baroreflex sensitivity and a paradoxical decrease in cardio-vagal components of heart rate and systolic arterial pressure variability in SHRs. CONCLUSION These results suggest that long-term activation of vagal parasympathetic pathways is beneficial in restoring autonomic balance in an animal model of neurogenic hypertension and might be an effective therapeutic approach for the management of hypertension.
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Khalyfa A, Gozal D. Connexins and Atrial Fibrillation in Obstructive Sleep Apnea. CURRENT SLEEP MEDICINE REPORTS 2018; 4:300-311. [PMID: 31106116 PMCID: PMC6516763 DOI: 10.1007/s40675-018-0130-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE OF THE REVIEW To summarize the potential interactions between obstructive sleep apnea (OSA), atrial fibrillation (AF), and connexins. RECENT FINDINGS OSA is highly prevalent in patients with cardiovascular disease, and is associated with increased risk for end-organ substantial morbidities linked to autonomic nervous system imbalance, increased oxidative stress and inflammation, ultimately leading to reduced life expectancy. Epidemiological studies indicate that OSA is associated with increased incidence and progression of coronary heart disease, heart failure, stroke, as well as arrhythmias, particularly AF. Conversely, AF is very common among subjects referred for suspected OSA, and the prevalence of AF increases with OSA severity. The interrelationships between AF and OSA along with the well-known epidemiological links between these two conditions and obesity may reflect shared pathophysiological pathways, which may depend on the intercellular diffusion of signaling molecules into either the extracellular space or require cell-to-cell contact. Connexin signaling is accomplished via direct exchanges of cytosolic molecules between adjacent cells at gap membrane junctions for cell-to-cell coupling. The role of connexins in AF is now quite well established, but the impact of OSA on cardiac connexins has only recently begun to be investigated. Understanding the biology and regulatory mechanisms of connexins in OSA at the transcriptional, translational, and post-translational levels will undoubtedly require major efforts to decipher the breadth and complexity of connexin functions in OSA-induced AF. SUMMARY The risk of end-organ morbidities has initiated the search for circulating mechanistic biomarker signatures and the implementation of biomarker-based algorithms for precision-based diagnosis and risk assessment. Here we summarize recent findings in OSA as they relate to AF risk, and also review potential mechanisms linking OSA, AF and connexins.
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Affiliation(s)
- Abdelnaby Khalyfa
- Department of Pediatrics, Biological Sciences Division, Pritzker School of Medicine, The University of Chicago, Chicago IL 60637, USA
| | - David Gozal
- Department of Child Health, University of Missouri School of Medicine, Columbia, MO 65201, USA
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Lucking EF, O'Connor KM, Strain CR, Fouhy F, Bastiaanssen TFS, Burns DP, Golubeva AV, Stanton C, Clarke G, Cryan JF, O'Halloran KD. Chronic intermittent hypoxia disrupts cardiorespiratory homeostasis and gut microbiota composition in adult male guinea-pigs. EBioMedicine 2018; 38:191-205. [PMID: 30446434 PMCID: PMC6306383 DOI: 10.1016/j.ebiom.2018.11.010] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 10/26/2018] [Accepted: 11/05/2018] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Carotid body (peripheral oxygen sensor) sensitisation is pivotal in the development of chronic intermittent hypoxia (CIH)-induced hypertension. We sought to determine if exposure to CIH, modelling human sleep apnoea, adversely affects cardiorespiratory control in guinea-pigs, a species with hypoxia-insensitive carotid bodies. We reasoned that CIH-induced disruption of gut microbiota would evoke cardiorespiratory morbidity. METHODS Adult male guinea-pigs were exposed to CIH (6.5% O2 at nadir, 6 cycles.hour-1) for 8 h.day-1 for 12 consecutive days. FINDINGS CIH-exposed animals established reduced faecal microbiota species richness, with increased relative abundance of Bacteroidetes and reduced relative abundance of Firmicutes bacteria. Urinary corticosterone and noradrenaline levels were unchanged in CIH-exposed animals, but brainstem noradrenaline concentrations were lower compared with sham. Baseline ventilation was equivalent in CIH-exposed and sham animals; however, respiratory timing variability, sigh frequency and ventilation during hypoxic breathing were all lower in CIH-exposed animals. Baseline arterial blood pressure was unaffected by exposure to CIH, but β-adrenoceptor-dependent tachycardia and blunted bradycardia during phenylephrine-induced pressor responses was evident compared with sham controls. INTERPRETATION Increased carotid body chemo-afferent signalling appears obligatory for the development of CIH-induced hypertension and elevated chemoreflex control of breathing commonly reported in mammals, with hypoxia-sensitive carotid bodies. However, we reveal that exposure to modest CIH alters gut microbiota richness and composition, brainstem neurochemistry, and autonomic control of heart rate, independent of carotid body sensitisation, suggesting modulation of breathing and autonomic homeostasis via the microbiota-gut-brainstem axis. The findings have relevance to human sleep-disordered breathing. FUNDING The Department of Physiology, and APC Microbiome Ireland, UCC.
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Affiliation(s)
- Eric F Lucking
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
| | - Karen M O'Connor
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland; Department of Anatomy & Neuroscience, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Conall R Strain
- Teagasc Food Research Centre, Moorepark, Fermoy, County Cork, Ireland
| | - Fiona Fouhy
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Teagasc Food Research Centre, Moorepark, Fermoy, County Cork, Ireland
| | - Thomaz F S Bastiaanssen
- Department of Anatomy & Neuroscience, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - David P Burns
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
| | - Anna V Golubeva
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Catherine Stanton
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Teagasc Food Research Centre, Moorepark, Fermoy, County Cork, Ireland
| | - Gerard Clarke
- Department of Psychiatry and Neurobehavioural Science, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - John F Cryan
- Department of Anatomy & Neuroscience, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Ken D O'Halloran
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland.
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Ramirez JM, Severs LJ, Ramirez SC, Agosto‐Marlin IM. Advances in cellular and integrative control of oxygen homeostasis within the central nervous system. J Physiol 2018; 596:3043-3065. [PMID: 29742297 PMCID: PMC6068258 DOI: 10.1113/jp275890] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Accepted: 04/04/2018] [Indexed: 12/31/2022] Open
Abstract
Mammals must continuously regulate the levels of O2 and CO2 , which is particularly important for the brain. Failure to maintain adequate O2 /CO2 homeostasis has been associated with numerous disorders including sleep apnoea, Rett syndrome and sudden infant death syndrome. But, O2 /CO2 homeostasis poses major regulatory challenges, even in the healthy brain. Neuronal activities change in a differentiated, spatially and temporally complex manner, which is reflected in equally complex changes in O2 demand. This raises important questions: is oxygen sensing an emergent property, locally generated within all active neuronal networks, and/or the property of specialized O2 -sensitive CNS regions? Increasing evidence suggests that the regulation of the brain's redox state involves properties that are intrinsic to many networks, but that specialized regions in the brainstem orchestrate the integrated control of respiratory and cardiovascular functions. Although the levels of O2 in arterial blood and the CNS are very different, neuro-glial interactions and purinergic signalling are critical for both peripheral and CNS chemosensation. Indeed, the specificity of neuroglial interactions seems to determine the differential responses to O2 , CO2 and the changes in pH.
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Affiliation(s)
- Jan Marino Ramirez
- Center for Integrative Brain ResearchSeattle Children's Research InstituteDepartment of Neurological SurgeryUniversity of Washington School of MedicineSeattleWAUSA
- Department of Physiology and BiophysicsUniversity of WashingtonSeattleWAUSA
| | - Liza J. Severs
- Department of Physiology and BiophysicsUniversity of WashingtonSeattleWAUSA
| | - Sanja C. Ramirez
- Center for Integrative Brain ResearchSeattle Children's Research InstituteDepartment of Neurological SurgeryUniversity of Washington School of MedicineSeattleWAUSA
| | - Ibis M. Agosto‐Marlin
- Center for Integrative Brain ResearchSeattle Children's Research InstituteDepartment of Neurological SurgeryUniversity of Washington School of MedicineSeattleWAUSA
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14
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Litvin DG, Dick TE, Smith CB, Jacono FJ. Lung-injury depresses glutamatergic synaptic transmission in the nucleus tractus solitarii via discrete age-dependent mechanisms in neonatal rats. Brain Behav Immun 2018; 70:398-422. [PMID: 29601943 PMCID: PMC6075724 DOI: 10.1016/j.bbi.2018.03.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 03/20/2018] [Accepted: 03/26/2018] [Indexed: 12/26/2022] Open
Abstract
Transition periods (TPs) are brief stages in CNS development where neural circuits can exhibit heightened vulnerability to pathologic conditions such as injury or infection. This susceptibility is due in part to specialized mechanisms of synaptic plasticity, which may become activated by inflammatory mediators released under pathologic conditions. Thus, we hypothesized that the immune response to lung injury (LI) mediated synaptic changes through plasticity-like mechanisms that depended on whether LI occurred just before or after a TP. We studied the impact of LI on brainstem 2nd-order viscerosensory neurons located in the nucleus tractus solitarii (nTS) during a TP for respiratory control spanning (postnatal day (P) 11-15). We injured the lungs of Sprague-Dawley rats by intratracheal instillation of Bleomycin (or saline) just before (P9-11) or after (P17-19) the TP. A week later, we prepared horizontal slices of the medulla and recorded spontaneous and evoked excitatory postsynaptic currents (sEPSCs/eEPSCs) in vitro from neurons in the nTS that received monosynaptic glutamatergic input from the tractus solitarii (TS). In rats injured before the TP (pre-TP), neurons exhibited blunted sEPSCs and TS-eEPSCs compared to controls. The decreased TS-eEPSCs were mediated by differences in postsynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic-acid receptors (AMPAR). Specifically, compared to controls, LI rats had more Ca2+-impermeable AMPARs (CI-AMPARs) as indicated by: 1) the absence of current-rectification, 2) decreased sensitivity to polyamine, 1-Naphthyl-acetyl-spermine-trihydrochloride (NASPM) and 3) augmented immunoreactive staining for the CI-AMPAR GluA2. Thus, pre-TP-LI acts postsynaptically to blunt glutamatergic transmission. The neuroimmune response to pre-TP-LI included microglia hyper-ramification throughout the nTS. Daily intraperitoneal administration of minocycline, an inhibitor of microglial/macrophage function prevented hyper-ramification and abolished the pre-TP-LI evoked synaptic changes. In contrast, rat-pups injured after the TP (post-TP) exhibited microglia hypo-ramification in the nTS and had increased sEPSC amplitudes/frequencies, and decreased TS-eEPSC amplitudes compared to controls. These synaptic changes were not associated with changes in CI-AMPARs, and instead involved greater TS-evoked use-dependent depression (reduced paired pulse ratio), which is a hallmark of presynaptic plasticity. Thus we conclude that LI regulates the efficacy of TS → nTS synapses through discrete plasticity-like mechanisms that are immune-mediated and depend on whether the injury occurs before or after the TP for respiratory control.
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Affiliation(s)
- David G Litvin
- Department of Physiology & Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, United States; Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, United States; Division of Pulmonary, Critical Care and Sleep Medicine, Louis Stokes VA Medical Center, Cleveland, OH 44106, United States
| | - Thomas E Dick
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, United States; Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, United States
| | - Corey B Smith
- Department of Physiology & Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, United States
| | - Frank J Jacono
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, United States; Division of Pulmonary, Critical Care and Sleep Medicine, Louis Stokes VA Medical Center, Cleveland, OH 44106, United States.
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15
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Ting JT, Lee BR, Chong P, Soler-Llavina G, Cobbs C, Koch C, Zeng H, Lein E. Preparation of Acute Brain Slices Using an Optimized N-Methyl-D-glucamine Protective Recovery Method. J Vis Exp 2018. [PMID: 29553547 DOI: 10.3791/53825] [Citation(s) in RCA: 138] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
This protocol is a practical guide to the N-methyl-D-glucamine (NMDG) protective recovery method of brain slice preparation. Numerous recent studies have validated the utility of this method for enhancing neuronal preservation and overall brain slice viability. The implementation of this technique by early adopters has facilitated detailed investigations into brain function using diverse experimental applications and spanning a wide range of animal ages, brain regions, and cell types. Steps are outlined for carrying out the protective recovery brain slice technique using an optimized NMDG artificial cerebrospinal fluid (aCSF) media formulation and enhanced procedure to reliably obtain healthy brain slices for patch clamp electrophysiology. With this updated approach, a substantial improvement is observed in the speed and reliability of gigaohm seal formation during targeted patch clamp recording experiments while maintaining excellent neuronal preservation, thereby facilitating challenging experimental applications. Representative results are provided from multi-neuron patch clamp recording experiments to assay synaptic connectivity in neocortical brain slices prepared from young adult transgenic mice and mature adult human neurosurgical specimens. Furthermore, the optimized NMDG protective recovery method of brain slicing is compatible with both juvenile and adult animals, thus resolving a limitation of the original methodology. In summary, a single media formulation and brain slicing procedure can be implemented across various species and ages to achieve excellent viability and tissue preservation.
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Affiliation(s)
| | - Brian R Lee
- Cell Types Program, Allen Institute for Brain Science
| | - Peter Chong
- Cell Types Program, Allen Institute for Brain Science
| | | | - Charles Cobbs
- The Ben and Catherine Ivy Center for Advanced Brain Tumor Treatment, Swedish Neuroscience Institute
| | - Christof Koch
- Cell Types Program, Allen Institute for Brain Science
| | - Hongkui Zeng
- Cell Types Program, Allen Institute for Brain Science
| | - Ed Lein
- Cell Types Program, Allen Institute for Brain Science
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16
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Baldy C, Chamberland S, Fournier S, Kinkead R. Sex-Specific Consequences of Neonatal Stress on Cardio-Respiratory Inhibition Following Laryngeal Stimulation in Rat Pups. eNeuro 2017; 4:ENEURO.0393-17.2017. [PMID: 29308430 PMCID: PMC5753062 DOI: 10.1523/eneuro.0393-17.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 12/15/2017] [Accepted: 12/18/2017] [Indexed: 11/21/2022] Open
Abstract
The presence of liquid near the larynx of immature mammals triggers prolonged apneas with significant O2 desaturations and bradycardias. When excessive, this reflex (the laryngeal chemoreflex; LCR) can be fatal. Our understanding of the origins of abnormal LCR are limited; however, perinatal stress and male sex are risk factors for cardio-respiratory failure in infants. Because exposure to stress during early life has deleterious and sex-specific consequences on brain development it is plausible that respiratory reflexes are vulnerable to neuroendocrine dysfunction. To address this issue, we tested the hypothesis that neonatal maternal separation (NMS) is sufficient to exacerbate LCR-induced cardio-respiratory inhibition in anesthetized rat pups. Stressed pups were separated from their mother 3 h/d from postnatal days 3 to 12. At P14-P15, pups were instrumented to monitor breathing, O2 saturation (Spo2), and heart rate. The LCR was activated by water injections near the larynx (10 µl). LCR-induced apneas were longer in stressed pups than controls; O2 desaturations and bradycardias were more profound, especially in males. NMS increased the frequency and amplitude of spontaneous EPSCs (sEPSCs) in the dorsal motor nucleus of the vagus (DMNV) of males but not females. The positive relationship between corticosterone and testosterone observed in stressed pups (males only) suggests that disruption of neuroendocrine function by stress is key to sex-based differences in abnormal LCR. Because testosterone application onto medullary slices augments EPSC amplitude only in males, we propose that testosterone-mediated enhancement of synaptic connectivity within the DMNV contributes to the male bias in cardio-respiratory inhibition following LCR activation in stressed pups.
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Affiliation(s)
- Cécile Baldy
- Department of Pediatrics, Centre de Recherche de l’Institut de Cardiologie et Pneumologie de Québec, Université Laval, Québec, G1V 4G5, Canada
| | - Simon Chamberland
- Department of Psychiatry and Neuroscience, Québec Mental Health Institute, Université Laval, Québec, G1J 2G3, Canada
| | - Stéphanie Fournier
- Department of Pediatrics, Centre de Recherche de l’Institut de Cardiologie et Pneumologie de Québec, Université Laval, Québec, G1V 4G5, Canada
| | - Richard Kinkead
- Department of Pediatrics, Centre de Recherche de l’Institut de Cardiologie et Pneumologie de Québec, Université Laval, Québec, G1V 4G5, Canada
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Barbic M, Moreno A, Harris TD, Kay MW. Detachable glass microelectrodes for recording action potentials in active moving organs. Am J Physiol Heart Circ Physiol 2017; 312:H1248-H1259. [PMID: 28476925 DOI: 10.1152/ajpheart.00741.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 04/11/2017] [Accepted: 04/27/2017] [Indexed: 12/17/2022]
Abstract
Here, we describe new detachable floating glass micropipette electrode devices that provide targeted action potential recordings in active moving organs without requiring constant mechanical constraint or pharmacological inhibition of tissue motion. The technology is based on the concept of a glass micropipette electrode that is held firmly during cell targeting and intracellular insertion, after which a 100-µg glass microelectrode, a "microdevice," is gently released to remain within the moving organ. The microdevices provide long-term recordings of action potentials, even during millimeter-scale movement of tissue in which the device is embedded. We demonstrate two different glass micropipette electrode holding and detachment designs appropriate for the heart (sharp glass microdevices for cardiac myocytes in rats, guinea pigs, and humans) and the brain (patch glass microdevices for neurons in rats). We explain how microdevices enable measurements of multiple cells within a moving organ that are typically difficult with other technologies. Using sharp microdevices, action potential duration was monitored continuously for 15 min in unconstrained perfused hearts during global ischemia-reperfusion, providing beat-to-beat measurements of changes in action potential duration. Action potentials from neurons in the hippocampus of anesthetized rats were measured with patch microdevices, which provided stable base potentials during long-term recordings. Our results demonstrate that detachable microdevices are an elegant and robust tool to record electrical activity with high temporal resolution and cellular level localization without disturbing the physiological working conditions of the organ.NEW & NOTEWORTHY Cellular action potential measurements within tissue using glass micropipette electrodes usually require tissue immobilization, potentially influencing the physiological relevance of the measurement. Here, we addressed this limitation with novel 100-µg detachable glass microelectrodes that can be precisely positioned to provide long-term measurements of action potential duration during unconstrained tissue movement.
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Affiliation(s)
- Mladen Barbic
- Applied Physics and Instrumentation Group, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia; and
| | - Angel Moreno
- Department of Biomedical Engineering, The George Washington University, Washington, District of Columbia
| | - Tim D Harris
- Applied Physics and Instrumentation Group, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia; and
| | - Matthew W Kay
- Department of Biomedical Engineering, The George Washington University, Washington, District of Columbia
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18
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Kwon Y, Picel K, Adabag S, Vo T, Taylor BC, Redline S, Stone K, Mehra R, Ancoli-Israel S, Ensrud KE. Sleep-disordered breathing and daytime cardiac conduction abnormalities on 12-lead electrocardiogram in community-dwelling older men. Sleep Breath 2016; 20:1161-1168. [PMID: 26971326 PMCID: PMC5018906 DOI: 10.1007/s11325-016-1326-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 01/26/2016] [Accepted: 02/22/2016] [Indexed: 12/20/2022]
Abstract
PURPOSE Nocturnal cardiac conduction abnormalities are commonly observed in patients with sleep-disordered breathing (SDB). However, few population-based studies have examined the association between SDB and daytime cardiac conduction abnormalities. METHODS We examined a random sample of 471 community-dwelling men, aged ≥67 years, enrolled in the multi-center Outcomes of Sleep Disorders in Older Men (MrOS Sleep) study. SDB severity was categorized using percent of total sleep time with oxygen saturation <90 % (%TST < 90) and apnea hypopnea index (AHI). Cardiac conduction parameters were assessed by resting 12-lead electrocardiography (ECG). All analyses were adjusted for age, site, β-blocker use, coronary heart disease, calcium channel blocker use, and use of antiarrhythmic medications. RESULTS Mean age was 77 ± 6 years, median %TST < 90 was 0.7 (IQR 0.00-3.40), and median AHI was 7.06 (IQR 2.55-15.32). Men with greater nocturnal hypoxemia (%TST < 90 ≥ 3.5 %) compared with those without hypoxemia (%TST < 90 < 1.0 %) had a lower odds of bradycardia (OR 0.55 [0.32-0.94]) and right bundle branch block (RBBB) (OR 0.24 [0.08-0.75]) but a higher odds of ventricular paced rhythm (OR 4.42 [1.29-15.19]). Heart rate (HR) increased in a graded manner with increasing %TST < 90 (p-trend 0.01) and increasing AHI (p-trend 0.006), but these gradients were small in absolute magnitude. There were no associations of SDB measures with other ECG conduction parameters. CONCLUSIONS Greater nocturnal hypoxemia in older men was associated with a lower prevalence of daytime sinus bradycardia and RBBB, a higher prevalence of ventricular paced rhythm, and higher resting HR.
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Affiliation(s)
- Younghoon Kwon
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
- Department of Medicine, Minneapolis VA Health Care System, Minneapolis, MN, USA
| | - Katherine Picel
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
- Department of Medicine, Minneapolis VA Health Care System, Minneapolis, MN, USA
| | - Selcuk Adabag
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
- Department of Medicine, Minneapolis VA Health Care System, Minneapolis, MN, USA
| | - Tien Vo
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - Brent C Taylor
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
- Department of Medicine, Minneapolis VA Health Care System, Minneapolis, MN, USA
| | - Susan Redline
- Brigham and Women's Hospital and Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Katie Stone
- Research Institute, California Pacific Medical Center, San Francisco, CA, USA
| | - Reena Mehra
- Department of Medicine, Cleveland Clinic, Cleveland, OH, USA
| | - Sonia Ancoli-Israel
- Department of Psychiatry, University of California-San Diego, La Jolla, CA, USA
| | - Kristine E Ensrud
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA.
- Department of Medicine, Minneapolis VA Health Care System, Minneapolis, MN, USA.
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19
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Sforza E, Martin MS, Barthélémy JC, Roche F. Is there an association between altered baroreceptor sensitivity and obstructive sleep apnoea in the healthy elderly? ERJ Open Res 2016; 2:00072-2016. [PMID: 27957483 PMCID: PMC5140016 DOI: 10.1183/23120541.00072-2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 07/24/2016] [Indexed: 11/05/2022] Open
Abstract
Obstructive sleep apnoea (OSA) is associated with a rise in cardiovascular risk in which increased sympathetic activity and depressed baroreceptor reflex sensitivity (BRS) have been proposed. We examined this association in a sample of healthy elderly subjects with unrecognised OSA. 801 healthy elderly (aged ≥65 years) subjects undergoing clinical, respiratory polygraphy and vascular assessment were examined. According to the apnoea-hypopnoea index (AHI), the subjects were stratified into no OSA, mild-moderate OSA and severe OSA cases. OSA was present in 62% of the sample, 62% being mild-moderate and 38% severe. No differences were found for BRS value according to sex and OSA severity. 54% of the group had normal BRS value, 36% mild impairment and 10% severe dysfunction. BRS was negatively associated with body mass index (p=0.006), 24-h systolic (p=0.001) and diastolic pressure (p=0.001), and oxygen desaturation index (ODI) (p=0.03). Regression analyses revealed that subjects with lower BRS were those with hypertension (OR 0.41, 95% CI 0.24-0.81; p=0.002) and overweight (OR 0.42, 95% CI 0.25-0.81; p=0.008), without the effect of AHI and ODI. In the healthy elderly, the presence of a severe BRS dysfunction affects a small amount of severe cases without effect on snorers and mild OSA. Hypertension and obesity seem to play a great role in BRS impairment.
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Affiliation(s)
- Emilia Sforza
- Service de Physiologie Clinique et de l'Exercice, Pole NOL, CHU, EA SNA-EPIS, Faculté de Médecine J. Lisfranc, UJM Saint-Etienne, PRES Université de Lyon, Saint-Etienne, France
| | - Magali Saint Martin
- Service de Physiologie Clinique et de l'Exercice, Pole NOL, CHU, EA SNA-EPIS, Faculté de Médecine J. Lisfranc, UJM Saint-Etienne, PRES Université de Lyon, Saint-Etienne, France; Centre Hélio Marin de la Côte D'Azur, Hyeres, France
| | - Jean Claude Barthélémy
- Service de Physiologie Clinique et de l'Exercice, Pole NOL, CHU, EA SNA-EPIS, Faculté de Médecine J. Lisfranc, UJM Saint-Etienne, PRES Université de Lyon, Saint-Etienne, France
| | - Frédéric Roche
- Service de Physiologie Clinique et de l'Exercice, Pole NOL, CHU, EA SNA-EPIS, Faculté de Médecine J. Lisfranc, UJM Saint-Etienne, PRES Université de Lyon, Saint-Etienne, France
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20
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Morgan BJ, Bates ML, Rio RD, Wang Z, Dopp JM. Oxidative stress augments chemoreflex sensitivity in rats exposed to chronic intermittent hypoxia. Respir Physiol Neurobiol 2016; 234:47-59. [PMID: 27595979 DOI: 10.1016/j.resp.2016.09.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 08/29/2016] [Accepted: 09/01/2016] [Indexed: 12/31/2022]
Abstract
Chronic exposure to intermittent hypoxia (CIH) elicits plasticity of the carotid sinus and phrenic nerves via reactive oxygen species (ROS). To determine whether CIH-induced alterations in ventilation, metabolism, and heart rate are also dependent on ROS, we measured responses to acute hypoxia in conscious rats after 14 and 21 d of either CIH or normoxia (NORM), with or without concomitant administration of allopurinol (xanthine oxidase inhibitor), combined allopurinol plus losartan (angiotensin II type 1 receptor antagonist), or apocynin (NADPH oxidase inhibitor). Carotid body nitrotyrosine production was measured by immunohistochemistry. CIH produced an increase in the ventilatory response to acute hypoxia that was virtually eliminated by all three pharmacologic interventions. CIH caused a robust increase in carotid body nitrotyrosine production that was greatly attenuated by allopurinol plus losartan and by apocynin but unaffected by allopurinol. CIH caused a decrease in metabolic rate and a reduction in hypoxic bradycardia. Both of these effects were prevented by allopurinol, allopurinol plus losartan, and apocynin.
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Affiliation(s)
- Barbara J Morgan
- John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health: University of Wisconsin, Madison, WI 53706, USA; Department of Orthopedics and Rehabilitation, School of Medicine and Public Health; University of Wisconsin, Madison, WI 53706, USA.
| | - Melissa L Bates
- Department of Health and Human Physiology, College of Liberal Arts and Sciences; University of Iowa, Iowa City, IA 52242, USA
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Universidad Autónoma de Chile, Santiago, Chile
| | - Zunyi Wang
- Department of Surgical Sciences, School of Veterinary Medicine; University of Wisconsin, Madison, WI 53706, USA
| | - John M Dopp
- Pharmacy Practice Division, School of Pharmacy; University of Wisconsin, Madison, WI 53705, USA
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21
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McKay JAA, McCulloch CL, Querido JS, Foster GE, Koehle MS, Sheel AW. The effect of consistent practice of yogic breathing exercises on the human cardiorespiratory system. Respir Physiol Neurobiol 2016; 233:41-51. [PMID: 27453559 DOI: 10.1016/j.resp.2016.07.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 07/09/2016] [Accepted: 07/20/2016] [Indexed: 11/28/2022]
Abstract
The purpose of this investigation was to quantify the cardiovascular, respiratory, and cerebrovascular effects of two common yogic breathing exercises (YBE): bhastrika and chaturbhuj; and to determine the effect of their consistent practice on chemosensitivity. The first study was cross-sectional and compared experienced yogic breathers (YB) with matched controls; whereas the second was a 10-week longitudinal training study. The results support four major findings. First chaturbhuj resulted in a hypoxic stimulus in experienced YB compared to control [end-tidal oxygen tension (PETO2), YB: 77.5±5.7mmHg, P<0.05; control: 94.3±12.0mmHg]. Second, performance of chaturbhuj resulted in cyclic oscillations of mean arterial pressure (MAP), heart rate (HR), and middle cerebral artery velocity (MCAv) consistent with the phases of respiration. Third, post training, performance of bhastrika reduced PETO2 (end breath-hold: 90.8 8±12.1mmHg) compared to rest (100.1±7.4, P<0.05); it also resulted in significantly increased MAP at end breath-hold (96.7±13.0mmHg) compared to rest (83.0±6.6mmHg, P<0.05) and significantly increased mean MCAv (end breath-hold: 87.4±23.0cm/s, P<0.05; rest: 55.8±26.3cm/s). Fourth, experienced YB had lower central chemosensitivity than controls (YB: 3.4±0.4; control: 4.6±1.2L/min/mmHg; P<0.05). In conclusion, YBE significantly alter end-tidal gases, resulting in complex oscillations of cardiovascular and cerebrovascular variables, and if practiced consistently, may reduce chemosensitivity.
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Affiliation(s)
- Joshua A A McKay
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Cara L McCulloch
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.
| | - Jordan S Querido
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Glen E Foster
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada; Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - Michael S Koehle
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada; Division of Sports Medicine, University of British Columbia, Vancouver, BC, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
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Abstract
Sleep apnea (SA) is increasing in prevalence and is commonly comorbid with hypertension. Chronic intermittent hypoxia is used to model the arterial hypoxemia seen in SA, and through this paradigm, the mechanisms that underlie SA-induced hypertension are becoming clear. Cyclic hypoxic exposure during sleep chronically stimulates the carotid chemoreflexes, inducing sensory long-term facilitation, and drives sympathetic outflow from the hindbrain. The elevated sympathetic tone drives hypertension and renal sympathetic activity to the kidneys resulting in increased plasma renin activity and eventually angiotensin II (Ang II) peripherally. Upon waking, when respiration is normalized, the sympathetic activity does not diminish. This is partially because of adaptations leading to overactivation of the hindbrain regions controlling sympathetic outflow such as the nucleus tractus solitarius (NTS), and rostral ventrolateral medulla (RVLM). The sustained sympathetic activity is also due to enhanced synaptic signaling from the forebrain through the paraventricular nucleus (PVN). During the waking hours, when the chemoreceptors are not exposed to hypoxia, the forebrain circumventricular organs (CVOs) are stimulated by peripherally circulating Ang II from the elevated plasma renin activity. The CVOs and median preoptic nucleus chronically activate the PVN due to the Ang II signaling. All together, this leads to elevated nocturnal mean arterial pressure (MAP) as a response to hypoxemia, as well as inappropriately elevated diurnal MAP in response to maladaptations.
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Affiliation(s)
- Brent Shell
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, EAD 332B, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Katelynn Faulk
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, EAD 332B, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - J Thomas Cunningham
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, EAD 332B, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA.
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Jameson H, Bateman R, Byrne P, Dyavanapalli J, Wang X, Jain V, Mendelowitz D. Oxytocin neuron activation prevents hypertension that occurs with chronic intermittent hypoxia/hypercapnia in rats. Am J Physiol Heart Circ Physiol 2016; 310:H1549-57. [PMID: 27016581 DOI: 10.1152/ajpheart.00808.2015] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 03/18/2016] [Indexed: 12/29/2022]
Abstract
Hypertension is a common outcome associated with obstructive sleep apnea (OSA), a prevalent yet poorly treated cardiovascular disease. Recent studies showed oxytocin (OXT), released from hypothalamic paraventricular nucleus (PVN) neurons, activates cardiac vagal neurons in the dorsal motor nucleus of the vagus (DMNX) and may blunt cardiovascular responses to stress. This study tests whether the release of OXT from PVN fibers in the DMNX is diminished with chronic intermittent hypoxia-hypercapnia (CIH/H) exposure, an animal model of OSA, and whether activation of PVN OXT neurons restores OXT release in the DMNX and prevents the hypertension resulting from CIH/H. To assess OXT release from PVN fibers, Chinese hamster ovarian (CHO) cells were engineered to be highly sensitive to OXT by stable expression of the human recombinant OXT receptor and the calcium indicator R-GECO1. PVN fibers in the DMNX were selectively photoactivated in vitro by expression of channelrhodopsin. The release of OXT onto CHO cells in the DMNX was blunted in rats exposed to 21 days of CIH/H. Chronic activation of PVN OXT neurons in vivo, using designer receptors exclusively activated by designer drugs, restored the release of OXT onto CHO cells in the DMNX. Chronic PVN OXT neuron activation in vivo also prevented the hypertension that occurred in conscious unrestrained telemetry-equipped sham rats exposed to 3 wk of CIH/H. These results demonstrate that chronic activation of OXT neurons restores the release of OXT from PVN fibers in the DMNX and prevents the hypertension that occurs with 3 wk of CIH/H exposure.
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Affiliation(s)
- Heather Jameson
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC; Institute for Biomedical Sciences, The George Washington University, Washington, DC
| | - Ryan Bateman
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC
| | - Peter Byrne
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC
| | - Jhansi Dyavanapalli
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC
| | - Xin Wang
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC; Institute for Biomedical Sciences, The George Washington University, Washington, DC
| | - Vivek Jain
- Department of Medicine, The George Washington University, Washington, DC
| | - David Mendelowitz
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC; Institute for Biomedical Sciences, The George Washington University, Washington, DC;
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Quality of Life Assessment After Maxillomandibular Advancement Surgery for Obstructive Sleep Apnea. J Oral Maxillofac Surg 2016; 74:1228-37. [PMID: 26917205 DOI: 10.1016/j.joms.2016.01.043] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 01/13/2016] [Accepted: 01/22/2016] [Indexed: 11/21/2022]
Abstract
PURPOSE Although maxillomandibular advancement (MMA) surgery is highly efficacious for the management of obstructive sleep apnea (OSA), little information exists regarding the subjective effect of this treatment modality. The present study was undertaken to investigate the effect of MMA on patient-perceived quality of life (QOL) in OSA. PATIENTS AND METHODS A retrospective cohort study of patients treated with MMA for OSA from May 2010 to April 2015 was performed. The primary outcome measure was a change in the QOL detected using the Ottawa Sleep Apnea Questionnaire (OSA-Q), which assesses the MMA-related changes in QOL with a 5-point Likert scale. The secondary outcome measure was a change in the apnea hypopnea index (AHI). RESULTS Twenty-two patients participated in the present study. The mean maxillary and mandibular advancement were 8.36 and 11.08 mm, respectively. The AHI decreased from 42.4 to 6.9 events per hour postoperatively (P < .001). The QOL improved significantly after MMA (OSA-Q score 3.98 ± 0.35; P < 001). The sleep quality (4.35 ± 0.63), daytime function (4.13 ± 0.46), physical health (4.19 ± 0.45), mental and emotional health (4.02 ± 0.55), and sexual health (3.78 ± 0.62) categories all improved postoperatively (P < .001). The MMA-related side effects did not adversely affect the QOL. CONCLUSIONS MMA for OSA significantly improves patient's subjective overall QOL, with few MMA-related side effects.
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Morgan BJ, Adrian R, Wang ZY, Bates ML, Dopp JM. Chronic intermittent hypoxia alters ventilatory and metabolic responses to acute hypoxia in rats. J Appl Physiol (1985) 2016; 120:1186-95. [PMID: 26917692 DOI: 10.1152/japplphysiol.00015.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 02/22/2016] [Indexed: 12/18/2022] Open
Abstract
We determined the effects of chronic exposure to intermittent hypoxia (CIH) on chemoreflex control of ventilation in conscious animals. Adult male Sprague-Dawley rats were exposed to CIH [nadir oxygen saturation (SpO2), 75%; 15 events/h; 10 h/day] or normoxia (NORM) for 21 days. We assessed the following responses to acute, graded hypoxia before and after exposures: ventilation (V̇e, via barometric plethysmography), V̇o2 and V̇co2 (analysis of expired air), heart rate (HR), and SpO2 (pulse oximetry via neck collar). We quantified hypoxia-induced chemoreceptor sensitivity by calculating the stimulus-response relationship between SpO2 and the ventilatory equivalent for V̇co2 (linear regression). An additional aim was to determine whether CIH causes proliferation of carotid body glomus cells (using bromodeoxyuridine). CIH exposure increased the slope of the V̇e/V̇co2/SpO2 relationship and caused hyperventilation in normoxia. Bromodeoxyuridine staining was comparable in CIH and NORM. Thus our CIH paradigm augmented hypoxic chemosensitivity without causing glomus cell proliferation.
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Affiliation(s)
- Barbara J Morgan
- John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; Department of Orthopedics and Rehabilitation, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin;
| | - Russell Adrian
- John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; Department of Orthopedics and Rehabilitation, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
| | - Zun-Yi Wang
- Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin
| | - Melissa L Bates
- Department of Health and Human Physiology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, Iowa; and
| | - John M Dopp
- Pharmacy Practice Division, School of Pharmacy, University of Wisconsin, Madison, Wisconsin
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MacFarlane PM, Mayer CA, Litvin DG. Microglia modulate brainstem serotonergic expression following neonatal sustained hypoxia exposure: implications for sudden infant death syndrome. J Physiol 2016; 594:3079-94. [PMID: 26659585 DOI: 10.1113/jp271845] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Accepted: 12/07/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Neonatal sustained hypoxia exposure modifies brainstem microglia and serotonin expression. The altered brainstem neurochemistry is associated with impaired ventilatory responses to acute hypoxia and mortality. The deleterious effects of sustained hypoxia exposure can be prevented by an inhibitor of activated microglia. These observations demonstrate a potential cause of the brainstem serotonin abnormalities thought to be involved in sudden infant death syndrome. ABSTRACT We showed previously that the end of the second postnatal week (days P11-15) represents a period of development during which the respiratory neural control system exhibits a heightened vulnerability to sustained hypoxia (SH, 11% O2 , 5 days) exposure. In the current study, we investigated whether the vulnerability to SH during the same developmental time period is associated with changes in brainstem serotonin (5-HT) expression and whether it can be prevented by the microglia inhibitor minocycline. Using whole-body plethysmography, SH attenuated the acute (5 min) hypoxic ventilatory response (HVR) and caused a high incidence of mortality compared to normoxia rats. SH also increased microglia cell numbers and decreased 5-HT immunoreactivity in the nucleus of the solitary tract (nTS) and dorsal motor nucleus of the vagus (DMNV). The attenuated HVR, mortality, and changes in nTS and DMNV immunoreactivity was prevented by minocycline (25 mg kg(-1) /2 days during SH). These data demonstrate that the 5-HT abnormalities in distinct respiratory neural control regions can be initiated by prolonged hypoxia exposure and may be modulated by microglia activity. These observations share several commonalities with the risk factors thought to underlie the aetiology of sudden infant death syndrome, including: (1) a vulnerable neonate; (2) a critical period of development; (3) evidence of hypoxia; (4) brainstem gliosis (particularly the nTS and DMNV); and (5) 5-HT abnormalities.
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Affiliation(s)
- P M MacFarlane
- Department of Pediatrics, Rainbow Babies & Children's Hospital, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - C A Mayer
- Department of Pediatrics, Rainbow Babies & Children's Hospital, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - D G Litvin
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106, USA
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The impact of chronic intermittent hypoxia on hematopoiesis and the bone marrow microenvironment. Pflugers Arch 2016; 468:919-32. [PMID: 26856724 PMCID: PMC4842224 DOI: 10.1007/s00424-016-1797-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 12/21/2015] [Accepted: 01/26/2016] [Indexed: 12/18/2022]
Abstract
Obstructive sleep apnea (OSA) is a highly prevalent sleep-related breathing disorder which is associated with patient morbidity and an elevated risk of developing hypertension and cardiovascular diseases. There is ample evidence for the involvement of bone marrow (BM) cells in the pathophysiology of cardiovascular diseases but a connection between OSA and modulation of the BM microenvironment had not been established. Here, we studied how chronic intermittent hypoxia (CIH) affected hematopoiesis and the BM microenvironment, in a rat model of OSA. We show that CIH followed by normoxia increases the bone marrow hypoxic area, increases the number of multipotent hematopoietic progenitors (CFU assay), promotes erythropoiesis, and increases monocyte counts. In the BM microenvironment of CIH-subjected animals, the number of VE-cadherin-expressing blood vessels, particularly sinusoids, increased, accompanied by increased smooth muscle cell coverage, while vWF-positive vessels decreased. Molecularly, we investigated the expression of endothelial cell-derived genes (angiocrine factors) that could explain the cellular phenotypes. Accordingly, we observed an increase in colony-stimulating factor 1, vascular endothelium growth factor, delta-like 4, and angiopoietin-1 expression. Our data shows that CIH induces vascular remodeling in the BM microenvironment, which modulates hematopoiesis, increasing erythropoiesis, and circulating monocytes. Our study reveals for the first time the effect of CIH in hematopoiesis and suggests that hematopoietic changes may occur in OSA patients.
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28
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Kim G, Elnabawi O, Shin D, Pae EK. Transient Intermittent Hypoxia Exposure Disrupts Neonatal Bone Strength. Front Pediatr 2016; 4:15. [PMID: 27014665 PMCID: PMC4779887 DOI: 10.3389/fped.2016.00015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Accepted: 02/22/2016] [Indexed: 12/20/2022] Open
Abstract
A brief intermittent hypoxia (IH, ambient O2 levels alternating between room air and 12% O2) for 1 h immediately after birth resulted in pancreatic islet dysfunction associated with zinc deficiency as previously reported. We hypothesized that IH exposure modulates zinc homeostasis in bone as well, which leads to increased bone fragility. To test this hypothesis, we used neonatal rats and human osteoblasts (HObs). To examine IH influences on osteoblasts devoid of neural influences, we quantified amounts of alkaline phosphatase and mineralization in IH-treated HObs. Bones harvested from IH-treated animals showed significantly reduced hardness and elasticity. The IH group also showed discretely decreased levels of alkaline phosphatase and mineralization amounts. The IH group showed a decreased expression of ZIP8 or Zrt and Irt-like protein 8 (a zinc uptake transporter), Runx2 (or Runt-related transcription factor 2, a master protein in bone formation), Collagen-1 (a major protein comprising the extracellular matrix of the bone), osteocalcin, and zinc content. When zinc was eliminated from the media containing HObs using a zinc chelate and added later with zinc sulfate, Runx2, ZIP8, and osteocalcin expression decreased first, and recovered with zinc supplementation. Adenovirus-mediated ZIP8 over-expression in osteoblasts increased mineralization significantly as well. We conclude that IH impairs zinc homeostasis in bones and osteoblasts, and that such disturbances decrease bone strength, which can be recovered by zinc supplementation.
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Affiliation(s)
- Gyuyoup Kim
- Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of Maryland , Baltimore, MD , USA
| | - Omar Elnabawi
- Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of Maryland , Baltimore, MD , USA
| | | | - Eung-Kwon Pae
- Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of Maryland , Baltimore, MD , USA
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Dergacheva O. Chronic intermittent hypoxia alters neurotransmission from lateral paragigantocellular nucleus to parasympathetic cardiac neurons in the brain stem. J Neurophysiol 2014; 113:380-9. [PMID: 25318765 DOI: 10.1152/jn.00302.2014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Patients with sleep-related disorders, including obstructive sleep apnea (OSA), have an increased risk of cardiovascular diseases. OSA events are more severe in rapid eye movement (REM) sleep. REM sleep further increases the risk of adverse cardiovascular events by diminishing cardioprotective parasympathetic activity. The mechanisms underlying REM sleep-related reduction in parasympathetic activity likely include activation of inhibitory input to cardiac vagal neurons (CVNs) in the brain stem originating from the lateral paragigantocellular nucleus (LPGi), a nucleus that plays a role in REM sleep control. This study tests the hypothesis that chronic intermittent hypoxia and hypercapnia (CIHH), an animal model of OSA, inhibits CVNs because of exaggeration of the GABAergic pathway from the LPGi to CVNs. GABAergic neurotransmission to CVNs evoked by electrical stimulation of the LPGi was examined with whole cell patch-clamp recordings in an in vitro brain slice preparation in rats exposed to CIHH and control rats. GABAergic synaptic events were enhanced after 4-wk CIHH in both male and female rats, to a greater degree in males. Acute hypoxia and hypercapnia (H/H) reversibly diminished the LPGi-evoked GABAergic neurotransmission to CVNs. However, GABAergic synaptic events were enhanced after acute H/H in CIHH male animals. Orexin-A elicited a reversible inhibition of LPGi-evoked GABAergic currents in control animals but evoked no significant changes in CIHH male rats. In conclusion, exaggerated inhibitory neurotransmission from the LPGi to CVNs in CIHH animals would reduce cardioprotective parasympathetic activity and enhance the risk of adverse cardiovascular events.
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Affiliation(s)
- Olga Dergacheva
- Department of Pharmacology and Physiology, The George Washington University, Washington, District of Columbia
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30
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Diogo LN, Monteiro EC. The efficacy of antihypertensive drugs in chronic intermittent hypoxia conditions. Front Physiol 2014; 5:361. [PMID: 25295010 PMCID: PMC4170135 DOI: 10.3389/fphys.2014.00361] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 09/03/2014] [Indexed: 12/22/2022] Open
Abstract
Sleep apnea/hypopnea disorders include centrally originated diseases and obstructive sleep apnea (OSA). This last condition is renowned as a frequent secondary cause of hypertension (HT). The mechanisms involved in the pathogenesis of HT can be summarized in relation to two main pathways: sympathetic nervous system stimulation mediated mainly by activation of carotid body (CB) chemoreflexes and/or asphyxia, and, by no means the least important, the systemic effects of chronic intermittent hypoxia (CIH). The use of animal models has revealed that CIH is the critical stimulus underlying sympathetic activity and hypertension, and that this effect requires the presence of functional arterial chemoreceptors, which are hyperactive in CIH. These models of CIH mimic the HT observed in humans and allow the study of CIH independently without the mechanical obstruction component. The effect of continuous positive airway pressure (CPAP), the gold standard treatment for OSA patients, to reduce blood pressure seems to be modest and concomitant antihypertensive therapy is still required. We focus this review on the efficacy of pharmacological interventions to revert HT associated with CIH conditions in both animal models and humans. First, we explore the experimental animal models, developed to mimic HT related to CIH, which have been used to investigate the effect of antihypertensive drugs (AHDs). Second, we review what is known about drug efficacy to reverse HT induced by CIH in animals. Moreover, findings in humans with OSA are cited to demonstrate the lack of strong evidence for the establishment of a first-line antihypertensive regimen for these patients. Indeed, specific therapeutic guidelines for the pharmacological treatment of HT in these patients are still lacking. Finally, we discuss the future perspectives concerning the non-pharmacological and pharmacological management of this particular type of HT.
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Affiliation(s)
- Lucilia N Diogo
- Centro de Estudos de Doenças Crónicas, CEDOC, NOVA Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa Lisboa, Portugal
| | - Emília C Monteiro
- Centro de Estudos de Doenças Crónicas, CEDOC, NOVA Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa Lisboa, Portugal
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