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Gama de Barcellos Filho P, Dantzler HA, Hasser EM, Kline DD. Oxytocin and corticotropin-releasing hormone exaggerate nucleus tractus solitarii neuronal and synaptic activity following chronic intermittent hypoxia. J Physiol 2024. [PMID: 38698722 DOI: 10.1113/jp286069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 03/28/2024] [Indexed: 05/05/2024] Open
Abstract
Chronic intermittent hypoxia (CIH) in rodents mimics the hypoxia-induced elevation of blood pressure seen in individuals experiencing episodic breathing. The brainstem nucleus tractus solitarii (nTS) is the first site of visceral sensory afferent integration, and thus is critical for cardiorespiratory homeostasis and its adaptation during a variety of stressors. In addition, the paraventricular nucleus of the hypothalamus (PVN), in part through its nTS projections that contain oxytocin (OT) and/or corticotropin-releasing hormone (CRH), contributes to cardiorespiratory regulation. Within the nTS, these PVN-derived neuropeptides alter nTS activity and the cardiorespiratory response to hypoxia. Nevertheless, their contribution to nTS activity after CIH is not fully understood. We hypothesized that OT and CRH would increase nTS activity to a greater extent following CIH, and co-activation of OT+CRH receptors would further magnify nTS activity. Our data show that compared to their normoxic controls, 10 days' CIH exaggerated nTS discharge, excitatory synaptic currents and Ca2+ influx in response to CRH, which were further enhanced by the addition of OT. CIH increased the tonic functional contribution of CRH receptors, which occurred with elevation of mRNA and protein. Together, our data demonstrate that intermittent hypoxia exaggerates the expression and function of neuropeptides on nTS activity. KEY POINTS: Episodic breathing and chronic intermittent hypoxia (CIH) are associated with autonomic dysregulation, including elevated sympathetic nervous system activity. Altered nucleus tractus solitarii (nTS) activity contributes to this response. Neurons originating in the paraventricular nucleus (PVN), including those containing oxytocin (OT) and corticotropin-releasing hormone (CRH), project to the nTS, and modulate the cardiorespiratory system. Their role in CIH is unknown. In this study, we focused on OT and CRH individually and together on nTS activity from rats exposed to either CIH or normoxia control. We show that after CIH, CRH alone and with OT increased to a greater extent overall nTS discharge, neuronal calcium influx, synaptic transmission to second-order nTS neurons, and OT and CRH receptor expression. These results provide insights into the underlying circuits and mechanisms contributing to autonomic dysfunction during periods of episodic breathing.
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Affiliation(s)
- Procopio Gama de Barcellos Filho
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, USA
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA
| | - Heather A Dantzler
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, USA
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA
| | - Eileen M Hasser
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, USA
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA
| | - David D Kline
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, USA
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA
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2
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Appiah CB, Gardner JJ, Farmer GE, Cunningham RL, Cunningham JT. Chronic intermittent hypoxia-induced hypertension: the impact of sex hormones. Am J Physiol Regul Integr Comp Physiol 2024; 326:R333-R345. [PMID: 38406843 DOI: 10.1152/ajpregu.00258.2023] [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: 11/16/2023] [Revised: 02/12/2024] [Accepted: 02/15/2024] [Indexed: 02/27/2024]
Abstract
Obstructive sleep apnea, a common form of sleep-disordered breathing, is characterized by intermittent cessations of breathing that reduce blood oxygen levels and contribute to the development of hypertension. Hypertension is a major complication of obstructive sleep apnea that elevates the risk of end-organ damage. Premenopausal women have a lower prevalence of obstructive sleep apnea and cardiovascular disease than men and postmenopausal women, suggesting that sex hormones play a role in the pathophysiology of sleep apnea-related hypertension. The lack of protection in men and postmenopausal women implicates estrogen and progesterone as protective agents but testosterone as a permissive agent in sleep apnea-induced hypertension. A better understanding of how sex hormones contribute to the pathophysiology of sleep apnea-induced hypertension is important for future research and possible hormone-based interventions. The effect of sex on the pathophysiology of sleep apnea and associated intermittent hypoxia-induced hypertension is of important consideration in the screening, diagnosis, and treatment of the disease and its cardiovascular complications. This review summarizes our current understanding of the impact of sex hormones on blood pressure regulation in sleep apnea with a focus on sex differences.
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Affiliation(s)
- Cephas B Appiah
- Department of Physiology and Anatomy, School of Biomedical Sciences, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas, United States
| | - Jennifer J Gardner
- Department of Physiology and Anatomy, School of Biomedical Sciences, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas, United States
| | - George E Farmer
- Department of Physiology and Anatomy, School of Biomedical Sciences, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas, United States
| | - Rebecca L Cunningham
- Department of Pharmaceutical Sciences, System College of Pharmacy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas, United States
| | - J Thomas Cunningham
- Department of Physiology and Anatomy, School of Biomedical Sciences, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas, United States
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3
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Song R, Baker TL, Watters JJ, Kumar S. Obstructive Sleep Apnea-Associated Intermittent Hypoxia-Induced Immune Responses in Males, Pregnancies, and Offspring. Int J Mol Sci 2024; 25:1852. [PMID: 38339130 PMCID: PMC10856042 DOI: 10.3390/ijms25031852] [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: 12/27/2023] [Revised: 01/22/2024] [Accepted: 02/01/2024] [Indexed: 02/12/2024] Open
Abstract
Obstructive sleep apnea (OSA), a respiratory sleep disorder associated with cardiovascular diseases, is more prevalent in men. However, OSA occurrence in pregnant women rises to a level comparable to men during late gestation, creating persistent effects on both maternal and offspring health. The exact mechanisms behind OSA-induced cardiovascular diseases remain unclear, but inflammation and oxidative stress play a key role. Animal models using intermittent hypoxia (IH), a hallmark of OSA, reveal several pro-inflammatory signaling pathways at play in males, such as TLR4/MyD88/NF-κB/MAPK, miRNA/NLRP3, and COX signaling, along with shifts in immune cell populations and function. Limited evidence suggests similarities in pregnancies and offspring. In addition, suppressing these inflammatory molecules ameliorates IH-induced inflammation and tissue injury, providing new potential targets to treat OSA-associated cardiovascular diseases. This review will focus on the inflammatory mechanisms linking IH to cardiovascular dysfunction in males, pregnancies, and their offspring. The goal is to inspire further investigations into the understudied populations of pregnant females and their offspring, which ultimately uncover underlying mechanisms and therapeutic interventions for OSA-associated diseases.
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Affiliation(s)
- Ruolin Song
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA; (R.S.); (T.L.B.); (J.J.W.)
| | - Tracy L. Baker
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA; (R.S.); (T.L.B.); (J.J.W.)
| | - Jyoti J. Watters
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA; (R.S.); (T.L.B.); (J.J.W.)
| | - Sathish Kumar
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA; (R.S.); (T.L.B.); (J.J.W.)
- Department of Obstetrics and Gynecology, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53792, USA
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Takeda Y, Kimura F, Takasawa S. Possible Molecular Mechanisms of Hypertension Induced by Sleep Apnea Syndrome/Intermittent Hypoxia. Life (Basel) 2024; 14:157. [PMID: 38276286 PMCID: PMC10821044 DOI: 10.3390/life14010157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/13/2024] [Accepted: 01/15/2024] [Indexed: 01/27/2024] Open
Abstract
Intermittent hypoxia (IH) is a central characteristic of sleep apnea syndrome (SAS), and it subjects cells in the body to repetitive apnea, chronic hypoxia, oxygen desaturation, and hypercapnia. Since SAS is linked to various serious cardiovascular complications, especially hypertension, many studies have been conducted to elucidate the mechanism of hypertension induced by SAS/IH. Hypertension in SAS is associated with numerous cardiovascular disorders. As hypertension is the most common complication of SAS, cell and animal models to study SAS/IH have developed and provided lots of hints for elucidating the molecular mechanisms of hypertension induced by IH. However, the detailed mechanisms are obscure and under investigation. This review outlines the molecular mechanisms of hypertension in IH, which include the regulation systems of reactive oxygen species (ROS) that activate the renin-angiotensin system (RAS) and catecholamine biosynthesis in the sympathetic nervous system, resulting in hypertension. And hypoxia-inducible factors (HIFs), Endotheline 1 (ET-1), and inflammatory factors are also mentioned. In addition, we will discuss the influences of SAS/IH in cardiovascular dysfunction and the relationship of microRNA (miRNA)s to regulate the key molecules in each mechanism, which has become more apparent in recent years. These findings provide insight into the pathogenesis of SAS and help in the development of future treatments.
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Affiliation(s)
- Yoshinori Takeda
- Department of Biochemistry, Nara Medical University, 840 Shijo-cho, Kashihara 634-8521, Japan;
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara 634-8522, Japan;
| | - Fuminori Kimura
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara 634-8522, Japan;
| | - Shin Takasawa
- Department of Biochemistry, Nara Medical University, 840 Shijo-cho, Kashihara 634-8521, Japan;
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Prabhakar NR, Peng YJ, Nanduri J. Carotid body hypersensitivity in intermittent hypoxia and obtructive sleep apnoea. J Physiol 2023; 601:5481-5494. [PMID: 37029496 DOI: 10.1113/jp284111] [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: 01/26/2023] [Accepted: 03/29/2023] [Indexed: 04/09/2023] Open
Abstract
Carotid bodies are the principal sensory organs for detecting changes in arterial blood oxygen concentration, and the carotid body chemoreflex is a major regulator of the sympathetic tone, blood pressure and breathing. Intermittent hypoxia is a hallmark manifestation of obstructive sleep apnoea (OSA), which is a widespread respiratory disorder. In the first part of this review, we discuss the role of carotid bodies in heightened sympathetic tone and hypertension in rodents treated with intermittent hypoxia, and the underlying cellular, molecular and epigenetic mechanisms. We also present evidence for hitherto-uncharacterized role of carotid body afferents in triggering cellular and molecular changes induced by intermittent hypoxia. In the second part of the review, we present evidence for a contribution of a hypersensitive carotid body to OSA and potential therapeutic intervention to mitigate OSA in a murine model.
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Affiliation(s)
- Nanduri R Prabhakar
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, Biological Sciences Division, University of Chicago, Chicago, Illinois, USA
| | - Ying-Jie Peng
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, Biological Sciences Division, University of Chicago, Chicago, Illinois, USA
| | - Jayasri Nanduri
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, Biological Sciences Division, University of Chicago, Chicago, Illinois, USA
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6
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Iturriaga R. Carotid body contribution to the physio-pathological consequences of intermittent hypoxia: role of nitro-oxidative stress and inflammation. J Physiol 2023; 601:5495-5507. [PMID: 37119020 DOI: 10.1113/jp284112] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 04/24/2023] [Indexed: 04/30/2023] Open
Abstract
Obstructive sleep apnoea (OSA), characterized by chronic intermittent hypoxia (CIH), is considered to be an independent risk for hypertension. The pathological cardiorespiratory consequences of OSA have been attributed to systemic oxidative stress, inflammation and sympathetic overflow induced by CIH, but an emerging body of evidence indicates that a nitro-oxidative and pro-inflammatory milieu within the carotid body (CB) is involved in the potentiation of CB chemosensory responses to hypoxia, which contribute to enhance the sympathetic activity. Accordingly, autonomic and cardiovascular alterations induced by CIH are critically dependent on an abnormally heightened CB chemosensory input to the nucleus of tractus solitarius (NTS), where second-order neurons project onto the rostral ventrolateral medulla (RVLM), activating pre-sympathetic neurons that control pre-ganglionic sympathetic neurons. CIH produces oxidative stress and neuroinflammation in the NTS and RVLM, which may contribute to the long-term irreversibility of the CIH-induced alterations. This brief review is mainly focused on the contribution of nitro-oxidative stress and pro-inflammatory molecules on the hyperactivation of the hypoxic chemoreflex pathway including the CB and the brainstem centres, and whether the persistence of autonomic and cardiorespiratory alterations may depend on the glial-related neuroinflammation induced by the enhanced CB chemosensory afferent input.
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Affiliation(s)
- Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Centro de Investigación en Fisiología y Medicina de Altura, Facultad de Ciencias de la Salud, Universidad de Antofagasta, Antofagasta, Chile
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7
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Yegen CH, Marchant D, Bernaudin JF, Planes C, Boncoeur E, Voituron N. Chronic pulmonary fibrosis alters the functioning of the respiratory neural network. Front Physiol 2023; 14:1205924. [PMID: 37383147 PMCID: PMC10293840 DOI: 10.3389/fphys.2023.1205924] [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: 04/14/2023] [Accepted: 06/02/2023] [Indexed: 06/30/2023] Open
Abstract
Some patients with idiopathic pulmonary fibrosis present impaired ventilatory variables characterised by low forced vital capacity values associated with an increase in respiratory rate and a decrease in tidal volume which could be related to the increased pulmonary stiffness. The lung stiffness observed in pulmonary fibrosis may also have an effect on the functioning of the brainstem respiratory neural network, which could ultimately reinforce or accentuate ventilatory alterations. To this end, we sought to uncover the consequences of pulmonary fibrosis on ventilatory variables and how the modification of pulmonary rigidity could influence the functioning of the respiratory neuronal network. In a mouse model of pulmonary fibrosis obtained by 6 repeated intratracheal instillations of bleomycin (BLM), we first observed an increase in minute ventilation characterised by an increase in respiratory rate and tidal volume, a desaturation and a decrease in lung compliance. The changes in these ventilatory variables were correlated with the severity of the lung injury. The impact of lung fibrosis was also evaluated on the functioning of the medullary areas involved in the elaboration of the central respiratory drive. Thus, BLM-induced pulmonary fibrosis led to a change in the long-term activity of the medullary neuronal respiratory network, especially at the level of the nucleus of the solitary tract, the first central relay of the peripheral afferents, and the Pre-Bötzinger complex, the inspiratory rhythm generator. Our results showed that pulmonary fibrosis induced modifications not only of pulmonary architecture but also of central control of the respiratory neural network.
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Affiliation(s)
- Céline-Hivda Yegen
- Laboratoire Hypoxie & Poumon, UMR INSERM U1272, Université Sorbonne Paris Nord, Bobigny, France
| | - Dominique Marchant
- Laboratoire Hypoxie & Poumon, UMR INSERM U1272, Université Sorbonne Paris Nord, Bobigny, France
| | - Jean-François Bernaudin
- Laboratoire Hypoxie & Poumon, UMR INSERM U1272, Université Sorbonne Paris Nord, Bobigny, France
- Faculté de Médecine, Sorbonne Université, Paris, France
| | - Carole Planes
- Laboratoire Hypoxie & Poumon, UMR INSERM U1272, Université Sorbonne Paris Nord, Bobigny, France
- Service de Physiologie et d’Explorations Fonctionnelles, Hôpital Avicenne, APHP, Bobigny, France
| | - Emilie Boncoeur
- Laboratoire Hypoxie & Poumon, UMR INSERM U1272, Université Sorbonne Paris Nord, Bobigny, France
| | - Nicolas Voituron
- Laboratoire Hypoxie & Poumon, UMR INSERM U1272, Université Sorbonne Paris Nord, Bobigny, France
- Département STAPS, Université Sorbonne Paris Nord, Bobigny, France
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Lv R, Liu X, Zhang Y, Dong N, Wang X, He Y, Yue H, Yin Q. Pathophysiological mechanisms and therapeutic approaches in obstructive sleep apnea syndrome. Signal Transduct Target Ther 2023; 8:218. [PMID: 37230968 DOI: 10.1038/s41392-023-01496-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 05/09/2023] [Accepted: 05/11/2023] [Indexed: 05/27/2023] Open
Abstract
Obstructive sleep apnea syndrome (OSAS) is a common breathing disorder in sleep in which the airways narrow or collapse during sleep, causing obstructive sleep apnea. The prevalence of OSAS continues to rise worldwide, particularly in middle-aged and elderly individuals. The mechanism of upper airway collapse is incompletely understood but is associated with several factors, including obesity, craniofacial changes, altered muscle function in the upper airway, pharyngeal neuropathy, and fluid shifts to the neck. The main characteristics of OSAS are recurrent pauses in respiration, which lead to intermittent hypoxia (IH) and hypercapnia, accompanied by blood oxygen desaturation and arousal during sleep, which sharply increases the risk of several diseases. This paper first briefly describes the epidemiology, incidence, and pathophysiological mechanisms of OSAS. Next, the alterations in relevant signaling pathways induced by IH are systematically reviewed and discussed. For example, IH can induce gut microbiota (GM) dysbiosis, impair the intestinal barrier, and alter intestinal metabolites. These mechanisms ultimately lead to secondary oxidative stress, systemic inflammation, and sympathetic activation. We then summarize the effects of IH on disease pathogenesis, including cardiocerebrovascular disorders, neurological disorders, metabolic diseases, cancer, reproductive disorders, and COVID-19. Finally, different therapeutic strategies for OSAS caused by different causes are proposed. Multidisciplinary approaches and shared decision-making are necessary for the successful treatment of OSAS in the future, but more randomized controlled trials are needed for further evaluation to define what treatments are best for specific OSAS patients.
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Affiliation(s)
- Renjun Lv
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, 730000, China
| | - Xueying Liu
- Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, 250021, China
| | - Yue Zhang
- Department of Geriatrics, the 2nd Medical Center, Chinese PLA General Hospital, Beijing, 100853, China
| | - Na Dong
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, 730000, China
| | - Xiao Wang
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, 730000, China
| | - Yao He
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, 730000, China
| | - Hongmei Yue
- Department of Pulmonary and Critical Care Medicine, The First Hospital of Lanzhou University, Lanzhou, 730000, China.
| | - Qingqing Yin
- Department of Geriatric Neurology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, 250021, China.
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Zhang Z, Kalra H, Delzell MC, Jedlicka CR, Vasilyev M, Vasileva A, Tomasson MH, Bates ML. CORP: Sources and degrees of variability in whole animal intermittent hypoxia experiments. J Appl Physiol (1985) 2023; 134:1207-1215. [PMID: 36958346 PMCID: PMC10151045 DOI: 10.1152/japplphysiol.00643.2022] [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: 10/27/2022] [Revised: 02/17/2023] [Accepted: 03/12/2023] [Indexed: 03/25/2023] Open
Abstract
Chamber exposures are commonly used to evaluate the physiological and pathophysiological consequences of intermittent hypoxia in animal models. Researchers in this field use both commercial and custom-built chambers in their experiments. The purpose of this Cores of Reproducibility in Physiology paper is to demonstrate potential sources of variability in these systems that researchers should consider. Evaluating the relationship between arterial oxygen saturation and inspired oxygen concentration, we found that there are important sex-dependent differences in the commonly used C57BL6/J mouse model. The time delay of the oxygen sensor that provides feedback to the system during the ramp-down and ramp-up phases was different, limiting the number of cycles per hour that can be conducted and the overall stability of the oxygen concentration. The time to reach the hypoxic and normoxic hold stages, and the overall oxygen concentration, were impacted by the cycle number. These variables were further impacted by whether there are animals present in the chamber, highlighting the importance of verifying the cycling frequency with animals in the chamber. At ≤14 cycles/h, instability in the chamber oxygen concentration did not impact arterial oxygen saturation but may be important at higher cycle numbers. Taken together, these data demonstrate the important sources of variability that justify reporting and verifying the target oxygen concentration, cycling frequency, and arterial oxygen concentration, particularly when comparing different animal models and chamber configurations.NEW & NOTEWORTHY Intermittent hypoxia exposures are commonly used in physiology and many investigators use chamber systems to perform these studies. Because of the variety of chamber systems and protocols used, it is important to understand the sources of variability in intermittent hypoxia experiments that can impact reproducibility. We demonstrate sources of variability that come from the animal model, the intermittent hypoxia protocol, and the chamber system that can impact reproducibility.
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Affiliation(s)
- Zishan Zhang
- Interdisciplinary Graduate Program in Molecular Medicine, University of Iowa, Iowa City, Iowa, United States
- Division of Hematology, Oncology, and Bone Marrow Transplantation, Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States
| | - Hardik Kalra
- Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa, United States
| | - Matthew C Delzell
- Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa, United States
- Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, Missouri, United States
| | - Charles R Jedlicka
- Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa, United States
| | - Mikhail Vasilyev
- Division of Hematology, Oncology, and Bone Marrow Transplantation, Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States
| | - Anastasiia Vasileva
- Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa, United States
| | - Michael H Tomasson
- Interdisciplinary Graduate Program in Molecular Medicine, University of Iowa, Iowa City, Iowa, United States
- Division of Hematology, Oncology, and Bone Marrow Transplantation, Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States
- Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa, United States
| | - Melissa L Bates
- Interdisciplinary Graduate Program in Molecular Medicine, University of Iowa, Iowa City, Iowa, United States
- Division of Hematology, Oncology, and Bone Marrow Transplantation, Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States
- Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa, United States
- Division of Neonatology, Department of Pediatrics, University of Iowa, Iowa City, Iowa, United States
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Ostrowski D, Heesch CM, Kline DD, Hasser EM. Nucleus tractus solitarii is required for the development and maintenance of phrenic and sympathetic long-term facilitation after acute intermittent hypoxia. Front Physiol 2023; 14:1120341. [PMID: 36846346 PMCID: PMC9949380 DOI: 10.3389/fphys.2023.1120341] [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: 12/09/2022] [Accepted: 01/26/2023] [Indexed: 02/11/2023] Open
Abstract
Exposure to acute intermittent hypoxia (AIH) induces prolonged increases (long term facilitation, LTF) in phrenic and sympathetic nerve activity (PhrNA, SNA) under basal conditions, and enhanced respiratory and sympathetic responses to hypoxia. The mechanisms and neurocircuitry involved are not fully defined. We tested the hypothesis that the nucleus tractus solitarii (nTS) is vital to augmentation of hypoxic responses and the initiation and maintenance of elevated phrenic (p) and splanchnic sympathetic (s) LTF following AIH. nTS neuronal activity was inhibited by nanoinjection of the GABAA receptor agonist muscimol before AIH exposure or after development of AIH-induced LTF. AIH but not sustained hypoxia induced pLTF and sLTF with maintained respiratory modulation of SSNA. nTS muscimol before AIH increased baseline SSNA with minor effects on PhrNA. nTS inhibition also markedly blunted hypoxic PhrNA and SSNA responses, and prevented altered sympathorespiratory coupling during hypoxia. Inhibiting nTS neuronal activity before AIH exposure also prevented the development of pLTF during AIH and the elevated SSNA after muscimol did not increase further during or following AIH exposure. Furthermore, nTS neuronal inhibition after the development of AIH-induced LTF substantially reversed but did not eliminate the facilitation of PhrNA. Together these findings demonstrate that mechanisms within the nTS are critical for initiation of pLTF during AIH. Moreover, ongoing nTS neuronal activity is required for full expression of sustained elevations in PhrNA following exposure to AIH although other regions likely also are important. Together, the data indicate that AIH-induced alterations within the nTS contribute to both the development and maintenance of pLTF.
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Affiliation(s)
- Daniela Ostrowski
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, United States,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States,Department of Biology, Truman State University, Kirksville, MO, United States
| | - Cheryl M. Heesch
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, United States,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States
| | - David D. Kline
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, United States,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States,Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, United States
| | - Eileen M. Hasser
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, United States,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States,Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, United States,*Correspondence: Eileen M. Hasser,
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11
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Jia S, Rybalchenko N, Kunwar K, Farmer GE, Little JT, Toney GM, Cunningham JT. Chronic intermittent hypoxia enhances glycinergic inhibition in nucleus tractus solitarius. J Neurophysiol 2022; 128:1383-1394. [PMID: 36321700 PMCID: PMC9678432 DOI: 10.1152/jn.00241.2022] [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] [Indexed: 11/05/2022] Open
Abstract
Chronic intermittent hypoxia (CIH), an animal model of sleep apnea, has been shown to alter the activity of second-order chemoreceptor neurons in the caudal nucleus of the solitary tract (cNTS). Although numerous studies have focused on excitatory plasticity, few studies have explored CIH-induced plasticity impacting inhibitory inputs to NTS neurons, and the roles of GABAergic and glycinergic inputs on heightened cNTS excitability following CIH are unknown. In addition, changes in astrocyte function may play a role in cNTS plasticity responses to CIH. This study tested the effects of a 7-day CIH protocol on miniature inhibitory postsynaptic currents (mIPSCs) in cNTS neurons receiving chemoreceptor afferents. Normoxia-treated rats primarily displayed GABA mIPSCs, whereas CIH-treated rats exhibited a shift toward combined GABA/glycine-mediated mIPSCs. CIH increased glycinergic mIPSC amplitude and area. This shift was not observed in dorsal motor nucleus of the vagus neurons or cNTS cells from females. Immunohistochemistry showed that strengthened glycinergic mIPSCs were associated with increased glycine receptor protein and were dependent on receptor trafficking in CIH-treated rats. In addition, CIH altered astrocyte morphology in the cNTS, and inactivation of astrocytes following CIH reduced glycine receptor-mediated mIPSC frequency and overall mIPSC amplitude. In cNTS, CIH produced changes in glycine signaling that appear to reflect increased trafficking of glycine receptors to the cell membrane. Increased glycine signaling in cNTS associated with CIH also appears to be dependent on astrocytes. Additional studies will be needed to determine how CIH influences glycine receptor expression and astrocyte function in cNTS.NEW & NOTEWORTHY Chronic intermittent hypoxia (CIH) has been used to mimic the hypoxemia associated with sleep apnea and determine how these hypoxemias influence neural function. The nucleus of the solitary tract is the main site for chemoreceptor input to the CNS, but how CIH influences NTS inhibition has not been determined. These studies show that CIH increases glycine-mediated miniature IPSCs through mechanisms that depend on protein trafficking and astrocyte activation.
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Affiliation(s)
- Shuping Jia
- 1Department of Physiology and Anatomy, University of Texas Health Science Center, Fort Worth, Texas
| | - Nataliya Rybalchenko
- 1Department of Physiology and Anatomy, University of Texas Health Science Center, Fort Worth, Texas
| | - Kishor Kunwar
- 2Microscopy Core, Division of Research and Innovation, University of Texas Health Science Center, Fort Worth, Texas
| | - George E. Farmer
- 1Department of Physiology and Anatomy, University of Texas Health Science Center, Fort Worth, Texas
| | - Joel T. Little
- 1Department of Physiology and Anatomy, University of Texas Health Science Center, Fort Worth, Texas
| | - Glenn M. Toney
- 3Department of Cellular & Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas
| | - J. Thomas Cunningham
- 1Department of Physiology and Anatomy, University of Texas Health Science Center, Fort Worth, Texas
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Ulland TK, Ewald AC, Knutson AO, Marino KM, Smith SMC, Watters JJ. Alzheimer's Disease, Sleep Disordered Breathing, and Microglia: Puzzling out a Common Link. Cells 2021; 10:2907. [PMID: 34831129 PMCID: PMC8616348 DOI: 10.3390/cells10112907] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 10/22/2021] [Accepted: 10/24/2021] [Indexed: 12/14/2022] Open
Abstract
Sleep Disordered Breathing (SDB) and Alzheimer's Disease (AD) are strongly associated clinically, but it is unknown if they are mechanistically associated. Here, we review data covering both the cellular and molecular responses in SDB and AD with an emphasis on the overlapping neuroimmune responses in both diseases. We extensively discuss the use of animal models of both diseases and their relative utilities in modeling human disease. Data presented here from mice exposed to intermittent hypoxia indicate that microglia become more activated following exposure to hypoxia. This also supports the idea that intermittent hypoxia can activate the neuroimmune system in a manner like that seen in AD. Finally, we highlight similarities in the cellular and neuroimmune responses between SDB and AD and propose that these similarities may lead to a pathological synergy between SDB and AD.
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Affiliation(s)
- Tyler K. Ulland
- Department of Pathology and Laboratory Medicine, University of Wisconsin Madison, Madison, WI 53705, USA; (T.K.U.); (K.M.M.)
- Neuroscience Training Program, University of Wisconsin Madison, Madison, WI 53705, USA
| | - Andrea C. Ewald
- Department of Comparative Biosciences, University of Wisconsin Madison, Madison, WI 53706, USA; (A.C.E.); (A.O.K.); (S.M.C.S.)
| | - Andrew O. Knutson
- Department of Comparative Biosciences, University of Wisconsin Madison, Madison, WI 53706, USA; (A.C.E.); (A.O.K.); (S.M.C.S.)
| | - Kaitlyn M. Marino
- Department of Pathology and Laboratory Medicine, University of Wisconsin Madison, Madison, WI 53705, USA; (T.K.U.); (K.M.M.)
- Neuroscience Training Program, University of Wisconsin Madison, Madison, WI 53705, USA
| | - Stephanie M. C. Smith
- Department of Comparative Biosciences, University of Wisconsin Madison, Madison, WI 53706, USA; (A.C.E.); (A.O.K.); (S.M.C.S.)
| | - Jyoti J. Watters
- Neuroscience Training Program, University of Wisconsin Madison, Madison, WI 53705, USA
- Department of Comparative Biosciences, University of Wisconsin Madison, Madison, WI 53706, USA; (A.C.E.); (A.O.K.); (S.M.C.S.)
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13
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Farmer GE, Little JT, Marciante AB, Cunningham JT. AT1a-dependent GABA A inhibition in the MnPO following chronic intermittent hypoxia. Am J Physiol Regul Integr Comp Physiol 2021; 321:R469-R481. [PMID: 34189959 PMCID: PMC8530756 DOI: 10.1152/ajpregu.00030.2021] [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: 02/01/2021] [Revised: 06/24/2021] [Accepted: 06/29/2021] [Indexed: 11/22/2022]
Abstract
Chronic intermittent hypoxia (CIH) is associated with diurnal hypertension, increased sympathetic nerve activity (SNA), and increases in circulating angiotensin II (ANG II). In rats, CIH increases angiotensin type 1 (AT1a) receptor expression in the median preoptic nucleus (MnPO), and pharmacological blockade or viral knockdown of this receptor prevents CIH-dependent increases in diurnal blood pressure. The current study investigates the role of AT1a receptor in modulating the activity of MnPO neurons following 7 days of CIH. Male Sprague-Dawley rats received MnPO injections of an adeno-associated virus with an shRNA against the AT1a receptor or a scrambled control. Rats were then exposed to CIH for 8 h a day for 7 days. In vitro, loose patch recordings of spontaneous action potential activity were made from labeled MnPO neurons in response to brief focal application of ANG II or the GABAA receptor agonist muscimol. In addition, MnPO K-Cl cotransporter isoform 2 (KCC2) protein expression was assessed using Western blot. CIH impaired the duration but not the magnitude of ANG II-mediated excitation in the MnPO. Both CIH and AT1a knockdown also impaired GABAA-mediated inhibition, and CIH with AT1a knockdown produced GABAA-mediated excitation. Recordings using the ratiometric Cl- indicator ClopHensorN showed CIH was associated with Cl- efflux in MnPO neurons that was associated with decreased KCC2 phosphorylation. The combination of CIH and AT1a knockdown attenuated reduced KCC2 phosphorylation seen with CIH alone. The current study shows that CIH, through the activity of AT1a receptors, can impair GABAA-mediated inhibition in the MnPO and contribute to sustained hypertension.
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Affiliation(s)
- George E Farmer
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - Joel T Little
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - Alexandria B Marciante
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - J Thomas Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
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14
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Iturriaga R, Alcayaga J, Chapleau MW, Somers VK. Carotid body chemoreceptors: physiology, pathology, and implications for health and disease. Physiol Rev 2021; 101:1177-1235. [PMID: 33570461 PMCID: PMC8526340 DOI: 10.1152/physrev.00039.2019] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The carotid body (CB) is the main peripheral chemoreceptor for arterial respiratory gases O2 and CO2 and pH, eliciting reflex ventilatory, cardiovascular, and humoral responses to maintain homeostasis. This review examines the fundamental biology underlying CB chemoreceptor function, its contribution to integrated physiological responses, and its role in maintaining health and potentiating disease. Emphasis is placed on 1) transduction mechanisms in chemoreceptor (type I) cells, highlighting the role played by the hypoxic inhibition of O2-dependent K+ channels and mitochondrial oxidative metabolism, and their modification by intracellular molecules and other ion channels; 2) synaptic mechanisms linking type I cells and petrosal nerve terminals, focusing on the role played by the main proposed transmitters and modulatory gases, and the participation of glial cells in regulation of the chemosensory process; 3) integrated reflex responses to CB activation, emphasizing that the responses differ dramatically depending on the nature of the physiological, pathological, or environmental challenges, and the interactions of the chemoreceptor reflex with other reflexes in optimizing oxygen delivery to the tissues; and 4) the contribution of enhanced CB chemosensory discharge to autonomic and cardiorespiratory pathophysiology in obstructive sleep apnea, congestive heart failure, resistant hypertension, and metabolic diseases and how modulation of enhanced CB reactivity in disease conditions may attenuate pathophysiology.
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Affiliation(s)
- Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile, and Centro de Excelencia en Biomedicina de Magallanes, Universidad de Magallanes, Punta Arenas, Chile
| | - Julio Alcayaga
- Laboratorio de Fisiología Celular, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Mark W Chapleau
- Department of Internal Medicine, University of Iowa and Department of Veterans Affairs Medical Center, Iowa City, Iowa
| | - Virend K Somers
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
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15
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Peng YJ, Su X, Wang B, Matthews T, Nanduri J, Prabhakar NR. Role of olfactory receptor78 in carotid body-dependent sympathetic activation and hypertension in murine models of chronic intermittent hypoxia. J Neurophysiol 2021; 125:2054-2067. [PMID: 33909496 DOI: 10.1152/jn.00067.2021] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic intermittent hypoxia (CIH) is a hallmark manifestation of obstructive sleep apnea (OSA), a widespread breathing disorder. CIH-treated rodents exhibit activation of the sympathetic nervous system and hypertension. Heightened carotid body (CB) activity has been implicated in CIH-induced hypertension. CB expresses high abundance of olfactory receptor (Olfr) 78, a G-protein coupled receptor. Olfr 78 null mice exhibit impaired CB sensory nerve response to acute hypoxia. Present study examined whether Olfr78 participates in CB-dependent activation of the sympathetic nervous system and hypertension in CIH-treated mice and in hemeoxygenase (HO)-2 null mice experiencing CIH as a consequence of naturally occurring OSA. CIH-treated wild-type (WT) mice showed hypertension, biomarkers of sympathetic nerve activation, and enhanced CB sensory nerve response to hypoxia and sensory long-term facilitation (sLTF), and these responses were absent in CIH-treated Olfr78 null mice. HO-2 null mice showed higher apnea index (AI) (58 ± 1.2 apneas/h) than WT mice (AI = 8 ± 0.8 apneas/h) and exhibited elevated blood pressure (BP), elevated plasma norepinephrine (NE) levels, and heightened CB sensory nerve response to hypoxia and sLTF. The magnitude of hypertension correlated with AI in HO-2 null mice. In contrast, HO-2/Olfr78 double null mice showed absence of elevated BP and plasma NE levels and augmented CB response to hypoxia and sLTF. These results demonstrate that Olfr78 participates in sympathetic nerve activation and hypertension and heightened CB activity in two murine models of CIH.NEW & NOTEWORTHY Carotid body (CB) sensory nerve activation is essential for sympathetic nerve excitation and hypertension in rodents treated with chronic intermittent hypoxia (CIH) simulating blood O2 profiles during obstructive sleep apnea (OSA). Here, we report that CIH-treated mice and hemeoxygenase (HO)-2-deficient mice, which show OSA phenotype, exhibit sympathetic excitation, hypertension, and CB activation. These effects are absent in Olfr78 null and Olfr78/HO-2 double null mice.
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Affiliation(s)
- Ying-Jie Peng
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, University of Chicago, Chicago, Illinois
| | - Xiaoyu Su
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, University of Chicago, Chicago, Illinois
| | - Benjamin Wang
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, University of Chicago, Chicago, Illinois
| | - Timothy Matthews
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, University of Chicago, Chicago, Illinois
| | - Jayasri Nanduri
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, University of Chicago, Chicago, Illinois
| | - Nanduri R Prabhakar
- Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, University of Chicago, Chicago, Illinois
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16
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Martinez D, Kline DD. The role of astrocytes in the nucleus tractus solitarii in maintaining central control of autonomic function. Am J Physiol Regul Integr Comp Physiol 2021; 320:R418-R424. [PMID: 33439770 PMCID: PMC8238142 DOI: 10.1152/ajpregu.00254.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 12/16/2020] [Accepted: 01/07/2021] [Indexed: 12/24/2022]
Abstract
The nucleus tractus solitarii (nTS) is the first central site for the termination and integration of autonomic and respiratory sensory information. Sensory afferents terminating in the nTS as well as the embedded nTS neurocircuitry release and utilize glutamate that is critical for maintenance of baseline cardiorespiratory parameters and initiating cardiorespiratory reflexes, including those activated by bouts of hypoxia. nTS astrocytes contribute to synaptic and neuronal activity through a variety of mechanisms, including gliotransmission and regulation of glutamate in the extracellular space via membrane-bound transporters. Here, we aim to highlight recent evidence for the role of astrocytes within the nTS and their regulation of autonomic and cardiorespiratory processes under normal and hypoxic conditions.
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Affiliation(s)
- Diana Martinez
- Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - David D Kline
- Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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17
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Prabhakar NR, Peng YJ, Nanduri J. Hypoxia-inducible factors and obstructive sleep apnea. J Clin Invest 2021; 130:5042-5051. [PMID: 32730232 DOI: 10.1172/jci137560] [Citation(s) in RCA: 120] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Intermittent hypoxia (IH) is a hallmark manifestation of obstructive sleep apnea (OSA), a widespread disorder of breathing. This Review focuses on the role of hypoxia-inducible factors (HIFs) in hypertension, type 2 diabetes (T2D), and cognitive decline in experimental models of IH patterned after O2 profiles seen in OSA. IH increases HIF-1α and decreases HIF-2α protein levels. Dysregulated HIFs increase reactive oxygen species (ROS) through HIF-1-dependent activation of pro-oxidant enzyme genes in addition to reduced transcription of antioxidant genes by HIF-2. ROS in turn activate chemoreflex and suppress baroreflex, thereby stimulating the sympathetic nervous system and causing hypertension. We also discuss how increased ROS generation by HIF-1 contributes to IH-induced insulin resistance and T2D as well as disrupted NMDA receptor signaling in the hippocampus, resulting in cognitive decline.
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18
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Wang W, Zheng Y, Li M, Lin S, Lin H. Recent Advances in Studies on the Role of Neuroendocrine Disorders in Obstructive Sleep Apnea-Hypopnea Syndrome-Related Atherosclerosis. Nat Sci Sleep 2021; 13:1331-1345. [PMID: 34349578 PMCID: PMC8326525 DOI: 10.2147/nss.s315375] [Citation(s) in RCA: 3] [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: 04/12/2021] [Accepted: 07/19/2021] [Indexed: 12/12/2022] Open
Abstract
Cardiovascular disease is a common cause of death worldwide, and atherosclerosis (AS) and obstructive sleep apnea-hypopnea syndrome (OSAHS) critically contribute to the initiation and progression of cardiovascular diseases. OSAHS promotes endothelial injury, vascular smooth muscle cell (VSMC) proliferation, abnormal lipid metabolism, and elevated arterial blood pressure. However, the exact OSAHS mechanism that causes AS remains unclear. The nervous system is widely distributed in the central and peripheral regions. It regulates appetite, energy metabolism, inflammation, oxidative stress, insulin resistance, and vasoconstriction by releasing regulatory factors and participates in the occurrence and development of AS. Studies showed that OSAHS can cause changes in neurophysiological plasticity and affect modulator release, suggesting that neuroendocrine dysfunction may be related to the OSAHS mechanism causing AS. In this article, we review the possible mechanisms of neuroendocrine disorders in the pathogenesis of OSAHS-induced AS and provide a new basis for further research on the development of corresponding effective intervention strategies.
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Affiliation(s)
- Wanda Wang
- Department of Cardiology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian Province, People's Republic of China
| | - Yanli Zheng
- Department of Cardiology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian Province, People's Republic of China
| | - Meimei Li
- Department of Cardiology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian Province, People's Republic of China
| | - Shu Lin
- Department of Cardiology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian Province, People's Republic of China.,Centre of Neurological and Metabolic Research, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian Province, People's Republic of China.,Diabetes and Metabolism Division, Garvan Institute of Medical Research, Sydney, NSW, 2010, Australia
| | - Huili Lin
- Department of Cardiology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian Province, People's Republic of China
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Brackley AD, Andrade MA, Toney GM. Intermittent hypercapnic hypoxia induces respiratory hypersensitivity to fentanyl accompanied by tonic respiratory depression by endogenous opioids. J Physiol 2020; 598:3239-3257. [PMID: 32415789 PMCID: PMC8162062 DOI: 10.1113/jp280021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 05/07/2020] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Sleep apnoea increases susceptibility to opioid-induced respiratory depression (OIRD). Endogenous opioids are implicated as a contributing factor in sleep apnoea. Rats exposed to sleep-phase chronic intermittent hypercapnic hypoxia (CIHH) for 7 days exhibited exaggerated OIRD to systemic fentanyl both while anaesthetized and artificially ventilated and while conscious and breathing spontaneously, implicating heightened CNS inhibitory efficacy of fentanyl. CIHH also induced tonic endogenous opioid suppression of neural inspiration. Sleep-related episodes of hypercapnic hypoxia, as in sleep apnoea, promote hypersensitivity to OIRD, with tonic respiratory depression by endogenous opioids implicated as a potential underlying cause. ABSTRACT Sleep apnoea (SA) increases opioid-induced respiratory depression (OIRD) and lethality. To test the hypothesis that this results from chronic intermittent bouts of hypercapnic hypoxia (CIHH) accompanying SA, we compared OIRD across continuously normoxic control rats and rats exposed to sleep-phase (8 h/day) CIHH for 1 week. OIRD sensitivity was first assessed in anaesthetized (urethane/α-chloralose), vagotomized and artificially ventilated rats by recording phrenic nerve activity (PNA) to index neural inspiration and quantify PNA burst inhibition to graded doses (0, 2, 20, 50 μg kg-1 , i.v.) of the synthetic opioid fentanyl. Fentanyl dose-dependently reduced PNA burst frequency (P = 0.0098-0.0001), while increasing the duration of burst quiescence at 50 μg kg-1 (P < 0.0001, n = 5-6/group/dose). CIHH shifted the fentanyl dose-phrenic burst frequency response curve to the left (P = 0.0163) and increased the duration of burst quiescence (P < 0.0001). During fentanyl recovery, PNA burst width was increased relative to baseline in normoxic and CIHH rats. Systemic naloxone (1 mg kg-1 , i.v.) reversed fentanyl-induced PNA arrest in both groups (P = 0.0002), and increased phrenic burst amplitude above baseline (P = 0.0113) in CIHH rats only. Differential sensitivity to anaesthesia as a cause of CIHH-related OIRD hypersensitivity was excluded by observing in conscious spontaneously breathing rats that fentanyl at 20 μg kg-1 (i.v.), which silenced PNA in anaesthetized rats, differentially increased breathing variability in normoxic versus CIHH rats (P = 0.0427), while significantly reducing breathing frequency (P < 0.0001) and periodicity (P = 0.0003) in CIHH rats only. Findings indicate that CIHH increased OIRD sensitivity, with tonic inspiratory depression by endogenous opioids as a likely contributing cause.
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Affiliation(s)
- Allison D Brackley
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229
- Center for Biomedical Neuroscience, University of Texas Health San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229
| | - Mary Ann Andrade
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229
| | - Glenn M Toney
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229
- Center for Biomedical Neuroscience, University of Texas Health San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229
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20
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Martinez D, Rogers RC, Hasser EM, Hermann GE, Kline DD. Loss of excitatory amino acid transporter restraint following chronic intermittent hypoxia contributes to synaptic alterations in nucleus tractus solitarii. J Neurophysiol 2020; 123:2122-2135. [PMID: 32347148 PMCID: PMC7311725 DOI: 10.1152/jn.00766.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Peripheral viscerosensory afferent signals are transmitted to the nucleus tractus solitarii (nTS) via release of glutamate. Following release, glutamate is removed from the extrasynaptic and synaptic cleft via excitatory amino acid transporters (EAATs), thus limiting glutamate receptor activation or over activation, and maintaining its working range. We have shown that EAAT block with the antagonist threo-β-benzyloxyaspartic acid (TBOA) depolarized nTS neurons and increased spontaneous excitatory postsynaptic current (sEPSC) frequency yet reduced the amplitude of afferent (TS)-evoked EPSCs (TS-EPSCs). Interestingly, chronic intermittent hypoxia (CIH), a model of obstructive sleep apnea (OSA), produces similar synaptic responses as EAAT block. We hypothesized EAAT expression or function are downregulated after CIH, and this reduction in glutamate removal contributes to the observed neurophysiological responses. To test this hypothesis, we used brain slice electrophysiology and imaging of glutamate release and TS-afferent Ca2+ to compare nTS properties of rats exposed to 10 days of normoxia (Norm; 21%O2) or CIH. Results show that EAAT blockade with (3S)-3-[[3-[[4-(trifluoromethyl)benzoyl]-amino]phenyl]methoxy]-l-aspartic acid (TFB-TBOA) in Norm caused neuronal depolarization, generation of an inward current, and increased spontaneous synaptic activity. The latter augmentation was eliminated by inclusion of tetrodotoxin in the perfusate. TS stimulation during TFB-TBOA also elevated extracellular glutamate and decreased presynaptic Ca2+ and TS-EPSC amplitude. In CIH, the effects of EAAT block are eliminated or attenuated. CIH reduced EAAT expression in nTS, which may contribute to the attenuated function seen in this condition. Therefore, CIH reduces EAAT influence on synaptic and neuronal activity, which may lead to the physiological consequences seen in OSA and CIH.NEW & NOTEWORTHY Removal of excitatory amino acid transporter (EAAT) restraint increases spontaneous synaptic activity yet decreases afferent [tractus solitarius (TS)]-driven excitatory postsynaptic current (EPSC) amplitude. In the chronic intermittent hypoxia model of obstructive sleep apnea, this restraint is lost due to reduction in EAAT expression and function. Thus EAATs are important in controlling elevated glutamatergic signaling, and loss of such control results in maladaptive synaptic signaling.
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Affiliation(s)
- Diana Martinez
- 1Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | | | - Eileen M. Hasser
- 1Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri,2Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | | | - David D. Kline
- 1Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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21
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Marciante AB, Wang LA, Little JT, Cunningham JT. Caspase lesions of PVN-projecting MnPO neurons block the sustained component of CIH-induced hypertension in adult male rats. Am J Physiol Heart Circ Physiol 2020; 318:H34-H48. [PMID: 31675258 PMCID: PMC6985804 DOI: 10.1152/ajpheart.00350.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 10/31/2019] [Accepted: 10/31/2019] [Indexed: 02/07/2023]
Abstract
Obstructive sleep apnea is characterized by interrupted breathing that leads to cardiovascular sequelae including chronic hypertension that can persist into the waking hours. Chronic intermittent hypoxia (CIH), which models the hypoxemia associated with sleep apnea, is sufficient to cause a sustained increase in blood pressure that involves the central nervous system. The median preoptic nucleus (MnPO) is an integrative forebrain region that contributes to blood pressure regulation and neurogenic hypertension. The MnPO projects to the paraventricular nucleus (PVN), a preautonomic region. We hypothesized that pathway-specific lesions of the projection from the MnPO to the PVN would attenuate the sustained component of chronic intermittent hypoxia-induced hypertension. Adult male Sprague-Dawley rats (250-300 g) were anesthetized with isoflurane and stereotaxically injected bilaterally in the PVN with a retrograde Cre-containing adeno-associated virus (AAV; AAV9.CMV.HI.eGFP-Cre.WPRE.SV40) and injected in the MnPO with caspase-3 (AAV5-flex-taCasp3-TEVp) or control virus (AAV5-hSyn-DIO-mCherry). Three weeks after the injections the rats were exposed to a 7-day intermittent hypoxia protocol. During chronic intermittent hypoxia, controls developed a diurnal hypertension that was blunted in rats with caspase lesions. Brain tissue processed for FosB immunohistochemistry showed decreased staining with caspase-induced lesions of MnPO and downstream autonomic-regulating nuclei. Chronic intermittent hypoxia significantly increased plasma levels of advanced oxidative protein products in controls, but this increase was blocked in caspase-lesioned rats. The results indicate that PVN-projecting MnPO neurons play a significant role in blood pressure regulation in the development of persistent chronic intermittent hypoxia hypertension.NEW & NOTEWORTHY Chronic intermittent hypoxia associated with obstructive sleep apnea increases oxidative stress and leads to chronic hypertension. Sustained hypertension may be mediated by angiotensin II-induced neural plasticity of excitatory median preoptic neurons in the forebrain that project to the paraventricular nucleus of the hypothalamus. Selective caspase lesions of these neurons interrupt the drive for sustained hypertension and cause a reduction in circulating oxidative protein products. This indicates that a functional connection between the forebrain and hypothalamus is necessary to drive diurnal hypertension associated with intermittent hypoxia. These results provide new information about central mechanisms that may contribute to neurogenic hypertension.
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Affiliation(s)
- Alexandria B Marciante
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - Lei A Wang
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - Joel T Little
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - J Thomas Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
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22
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Iturriaga R, Castillo-Galán S. Potential Contribution of Carotid Body-Induced Sympathetic and Renin-Angiotensin System Overflow to Pulmonary Hypertension in Intermittent Hypoxia. Curr Hypertens Rep 2019; 21:89. [PMID: 31599367 DOI: 10.1007/s11906-019-0995-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
PURPOSE OF REVIEW Obstructive sleep apnea (OSA), featured by chronic intermittent hypoxia (CIH), is an independent risk for systemic hypertension (HTN) and is associated with pulmonary hypertension (PH). The precise mechanisms underlying pulmonary vascular remodeling and PH in OSA are not fully understood. However, it has been suggested that lung tissue hypoxia, oxidative stress, and pro-inflammatory mediators following CIH exposure may contribute to PH. RECENT FINDINGS New evidences obtained in preclinical OSA models support that an enhanced carotid body (CB) chemosensory reactiveness to oxygen elicits sympathetic and renin-angiotensin system (RAS) overflow, which contributes to HTN. Moreover, the ablation of the CBs abolished the sympathetic hyperactivity and HTN in rodents exposed to CIH. Accordingly, it is plausible that the enhanced CB chemosensory reactivity may contribute to the pulmonary vascular remodeling and PH through the overactivation of the sympathetic-RAS axis. This hypothesis is supported by the facts that (i) CB stimulation increases pulmonary arterial pressure, (ii) denervation of sympathetic fibers in pulmonary arteries reduces pulmonary remodeling and pulmonary arterial hypertension (PAH) in humans, and (iii) administration of angiotensin-converting enzyme (ACE) or blockers of Ang II type 1 receptor (ATR1) ameliorates pulmonary remodeling and PH in animal models. In this review, we will discuss the supporting evidence for a plausible contribution of the CB-induced sympathetic-RAS axis overflow on pulmonary vascular remodeling and PH induced by CIH, the main characteristic of OSA.
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Affiliation(s)
- Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile.
| | - Sebastian Castillo-Galán
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile
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Milanick WJ, Polo-Parada L, Dantzler HA, Kline DD. Activation of alpha-1 adrenergic receptors increases cytosolic calcium in neurones of the paraventricular nucleus of the hypothalamus. J Neuroendocrinol 2019; 31:e12791. [PMID: 31494990 PMCID: PMC7003713 DOI: 10.1111/jne.12791] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 08/22/2019] [Accepted: 09/04/2019] [Indexed: 12/15/2022]
Abstract
Norepinephrine (NE) activates adrenergic receptors (ARs) in the hypothalamic paraventricular nucleus (PVN) to increase excitatory currents, depolarise neurones and, ultimately, augment neuro-sympathetic and endocrine output. Such cellular events are known to potentiate intracellular calcium ([Ca2+ ]i ); however, the role of NE with respect to modulating [Ca2+ ]i in PVN neurones and the mechanisms by which this may occur remain unclear. We evaluated the effects of NE on [Ca2+ ]i of acutely isolated PVN neurones using Fura-2 imaging. NE induced a slow increase in [Ca2+ ]i compared to artificial cerebrospinal fluid vehicle. NE-induced Ca2+ elevations were mimicked by the α1 -AR agonist phenylephrine (PE) but not by α2 -AR agonist clonidine (CLON). NE and PE but not CLON also increased the overall number of neurones that increase [Ca2+ ]i (ie, responders). Elimination of extracellular Ca2+ or intracellular endoplasmic reticulum Ca2+ stores abolished the increase in [Ca2+ ]i and reduced responders. Blockade of voltage-dependent Ca2+ channels abolished the α1 -AR induced increase in [Ca2+ ]i and number of responders, as did inhibition of phospholipase C inhibitor, protein kinase C and inositol triphosphate receptors. Spontaneous phasic Ca2+ events, however, were not altered by NE, PE or CLON. Repeated K+ -induced membrane depolarisation produced repetitive [Ca2+ ]i elevations. NE and PE increased baseline Ca2+ , whereas NE decreased the peak amplitude. CLON also decreased peak amplitude but did not affect baseline [Ca2+ ]i . Taken together, these data suggest receptor-specific influence of α1 and α2 receptors on the various modes of calcium entry in PVN neurones. They further suggest Ca2+ increase via α1 -ARs is co-dependent on extracellular Ca2+ influx and intracellular Ca2+ release, possibly via a phospholipase C inhibitor-mediated signalling cascade.
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Affiliation(s)
- William J. Milanick
- Department of Biomedical Sciences, University of Missouri, Columbia MO 65211
- Dalton Cardiovascular Research Center, University of Missouri, Columbia MO 65211
| | - Luis Polo-Parada
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia MO 65211
- Dalton Cardiovascular Research Center, University of Missouri, Columbia MO 65211
| | - Heather A. Dantzler
- Department of Biomedical Sciences, University of Missouri, Columbia MO 65211
- Dalton Cardiovascular Research Center, University of Missouri, Columbia MO 65211
| | - David D. Kline
- Department of Biomedical Sciences, University of Missouri, Columbia MO 65211
- Dalton Cardiovascular Research Center, University of Missouri, Columbia MO 65211
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24
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Balapattabi K, Farmer GE, Knapp BA, Little JT, Bachelor M, Yuan JP, Cunningham JT. Effects of salt-loading on supraoptic vasopressin neurones assessed by ClopHensorN chloride imaging. J Neuroendocrinol 2019; 31:e12752. [PMID: 31136029 PMCID: PMC7041405 DOI: 10.1111/jne.12752] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 05/16/2019] [Accepted: 05/23/2019] [Indexed: 12/13/2022]
Abstract
Salt-loading (SL) impairs GABAA inhibition of arginine vasopressin (AVP) neurones in the supraoptic nucleus (SON) of the hypothalamus. Based on previous studies, we hypothesised that SL activates tyrosine receptor kinase B (TrkB), down-regulating the activity of K+ /Cl- co-transporter2 (KCC2) and up-regulating Na+ /K+ /Cl- co-transporter1 (NKCC1). These changes in chloride transport would result in increased [Cl- ]i in SON AVP neurones. The study combined virally-mediated chloride imaging with ClopHensorN with a single-cell western blot analysis. An adeno-associated virus with ClopHensorN and a vasopressin promoter (AAV2-0VP1-ClopHensorN) was bilaterally injected in the SON of adult male Sprague-Dawley rats that were either euhydrated (Eu) or salt-loaded (SL) for 7 days. Acutely dissociated SON neurones expressing ClopHensorN were tested for decreases or increases in [Cl- ]i in response to focal application of the GABAA agonist muscimol (100 μmol L-1 ). SON AVP neurones from Eu rats showed muscimol-induced chloride influx (P < 0.05;23/35). SON AVP neurones from SL rats either significantly increased chloride efflux (P < 0.05;27/39) or did not change chloride flux (12/39). The SON AVP neurones that responded to muscimol appeared to be viable and expressed KCC2 and β-actin. Neurones that did not respond during chloride imaging did not show KCC2 and β-actin protein expression. The KCC2 antagonist (VU0240551,10 μmol L-1 ) significantly blocked the chloride influx in cells from Eu rats but did not affect cells from SL rats. A NKCC1 antagonist (bumetanide,10 μmol L-1 ) significantly blocked the chloride efflux in cells from SL rats but had no effect on cells from Eu rats. Blocking NKCC1 using bumetanide had less of an effect on the muscimol-induced Cl- influx in Eu rat neurones compared to the KCC2 antagonist. The TrkB antagonist (AnA-12) (50 μmol L-1 ) and protein kinase inhibitor (K252a) (100 nmol L-1 ) each significantly blocked chloride efflux in SON AVP neurones from SL rats. Salt-loading increases [Cl- ]i in SON AVP neurones via a TrKB-KCC2-NKCC1-dependent mechanism in rats.
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Affiliation(s)
- Kirthikaa Balapattabi
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - George E Farmer
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - Blayne A Knapp
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - Joel T Little
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - Martha Bachelor
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - Joseph P Yuan
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - J Thomas Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
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25
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O'Connor KM, Lucking EF, O'Halloran KD. Chronic intermittent hypoxia‐induced hypertension: An expired hypothesis laid to rest? Exp Physiol 2019; 104:1327-1328. [DOI: 10.1113/ep087868] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 06/04/2019] [Indexed: 12/23/2022]
Affiliation(s)
- Karen M. O'Connor
- Department of Physiology, School of MedicineCollege of Medicine & Health, University College Cork Cork Ireland
| | - Eric F. Lucking
- Department of Physiology, School of MedicineCollege of Medicine & Health, University College Cork Cork Ireland
| | - Ken D. O'Halloran
- Department of Physiology, School of MedicineCollege of Medicine & Health, University College Cork Cork Ireland
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26
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Shell B, Farmer GE, Nedungadi TP, Wang LA, Marciante AB, Snyder B, Cunningham RL, Cunningham JT. Angiotensin type 1a receptors in the median preoptic nucleus support intermittent hypoxia-induced hypertension. Am J Physiol Regul Integr Comp Physiol 2019; 316:R651-R665. [PMID: 30892911 PMCID: PMC6589598 DOI: 10.1152/ajpregu.00393.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/25/2019] [Accepted: 03/13/2019] [Indexed: 01/19/2023]
Abstract
Chronic intermittent hypoxia (CIH) is a model of the hypoxemia from sleep apnea that causes a sustained increase in blood pressure. Inhibition of the central renin-angiotensin system or FosB in the median preoptic nucleus (MnPO) prevents the sustained hypertensive response to CIH. We tested the hypothesis that angiotensin type 1a (AT1a) receptors in the MnPO, which are upregulated by CIH, contribute to this hypertension. In preliminary experiments, retrograde tract tracing studies showed AT1a receptor expression in MnPO neurons projecting to the paraventricular nucleus. Adult male rats were exposed to 7 days of intermittent hypoxia (cycling between 21% and 10% O2 every 6 min, 8 h/day during light phase). Seven days of CIH was associated with a FosB-dependent increase in AT1a receptor mRNA without changes in the permeability of the blood-brain barrier in the MnPO. Separate groups of rats were injected in the MnPO with an adeno-associated virus containing short hairpin (sh)RNA against AT1a receptors to test their role in intermittent hypoxia hypertension. Injections of shRNA against AT1a in MnPO blocked the increase in mRNA associated with CIH, prevented the sustained component of the hypertension during normoxia, and reduced circulating advanced oxidation protein products, an indicator of oxidative stress. Rats injected with shRNA against AT1a and exposed to CIH had less FosB staining in MnPO and the rostral ventrolateral medulla after intermittent hypoxia than rats injected with the control vector that were exposed to CIH. Our results indicate AT1a receptors in the MnPO contribute to the sustained blood pressure increase to intermittent hypoxia.
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MESH Headings
- Angiotensin II/administration & dosage
- Animals
- Blood Pressure/drug effects
- Disease Models, Animal
- Hypertension/etiology
- Hypertension/genetics
- Hypertension/metabolism
- Hypertension/physiopathology
- Hypoxia/complications
- Hypoxia/genetics
- Hypoxia/metabolism
- Hypoxia/physiopathology
- Injections, Intraventricular
- Male
- Oxidative Stress
- Preoptic Area/drug effects
- Preoptic Area/metabolism
- Preoptic Area/physiopathology
- Proto-Oncogene Proteins c-fos/genetics
- Proto-Oncogene Proteins c-fos/metabolism
- RNA Interference
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Rats, Sprague-Dawley
- Receptor, Angiotensin, Type 1/agonists
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Signal Transduction
- Up-Regulation
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Affiliation(s)
- Brent Shell
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - George E Farmer
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - T Prashant Nedungadi
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Lei A Wang
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Alexandria B Marciante
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Brina Snyder
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Rebecca L Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - J Thomas Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
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27
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Wang LA, Nguyen DH, Mifflin SW. CRHR2 (Corticotropin-Releasing Hormone Receptor 2) in the Nucleus of the Solitary Tract Contributes to Intermittent Hypoxia-Induced Hypertension. Hypertension 2019; 72:994-1001. [PMID: 30354709 DOI: 10.1161/hypertensionaha.118.11497] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
This study tested the hypothesis that CRHRs (corticotropin-releasing hormone receptors) in the nucleus of the solitary tract (NTS) contribute to the hypertension induced by intermittent hypoxia (IH) exposure in rats. Initial studies using in situ hybridization revealed low mRNA level of CRHR1 (CRH type 1 receptor) but high mRNA level of CRHR2 (CRH type 2 receptor) in the NTS. Calcium imaging studies on NTS slice preparations using Fura-2-acetoxymethyl ester demonstrated that CRH induced a transient increase of intracellular calcium level. The CRH-induced calcium response was reproduced in the presence of TTX (tetrodotoxin) but was abolished by depletion of extracellular calcium or by the L-type calcium channel blocker Nifedipine. The CRH-induced calcium influx was attenuated by the CRHR2 antagonist K41498 but not by the CRHR1 antagonist NBI-35 965. Calcium influx can be induced by the CRHR2 agonist Urocortin II but not by the CRHR1 agonist Stressin 1. IH exposure did not affect CRHR1 mRNA level but significantly decreased CRHR2 mRNA level and the CRH-induced calcium influx in the NTS. Further in vivo studies showed that intra-fourth ventricle infusion of K41498 did not affect the basal blood pressure but significantly attenuated the IH-induced hypertension; intra-fourth ventricle infusion of Urocortin II significantly increased basal blood pressure and exacerbated the IH-induced hypertension. Collectively, these results suggest that CRHR2 in the NTS contributes to the IH-induced hypertension; downregulation of CRHR2 and CRHR2-mediated calcium influx in the NTS may serve as an adaptive response to protect against the IH-induced hypertension.
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Affiliation(s)
- Lei A Wang
- From the Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth
| | - Dianna H Nguyen
- From the Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth
| | - Steve W Mifflin
- From the Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth
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28
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Snyder B, Duong P, Tenkorang M, Wilson EN, Cunningham RL. Rat Strain and Housing Conditions Alter Oxidative Stress and Hormone Responses to Chronic Intermittent Hypoxia. Front Physiol 2018; 9:1554. [PMID: 30459637 PMCID: PMC6232418 DOI: 10.3389/fphys.2018.01554] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Accepted: 10/17/2018] [Indexed: 12/15/2022] Open
Abstract
Sleep apnea has been associated with elevated risk for metabolic, cognitive, and cardiovascular disorders. Further, the role of hypothalamic–pituitary–adrenal (HPA) activation in sleep apnea has been controversial in human studies. Chronic intermittent hypoxia (CIH) is a rodent model, which mimics the hypoxemia experienced by patients with sleep apnea. Most studies of CIH in rats have been conducted in the Sprague Dawley rat strain. Previously published literature suggests different strains of rats exhibit various responses to disease models, and these effects can be further modulated by the housing conditions experienced by each strain. This variability in response is similar to what has been observed in clinical populations, especially with respect to the HPA system. To investigate if strain or housing (individual or pair-housed) can affect the results of CIH (AHI 8 or 10) treatment, we exposed individual and pair-housed Sprague Dawley and Long-Evans male rats to 7 days of CIH treatment. This was followed by biochemical analysis of circulating hormones, oxidative stress, and neurodegenerative markers. Both strain and housing conditions altered oxidative stress generation, hyperphosphorylated tau protein (tau tangles), circulating corticosterone and adrenocorticotropic hormone (ACTH), and weight metrics. Specifically, pair-housed Long-Evans rats were the most sensitive to CIH, which showed a significant association between oxidative stress generation and HPA activation under conditions of AHI of 8. These results suggest both strain and housing conditions can affect the outcomes of CIH.
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Affiliation(s)
- Brina Snyder
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States
| | - Phong Duong
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States
| | - Mavis Tenkorang
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States
| | - E Nicole Wilson
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States
| | - Rebecca L Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States
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29
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Farmer GE, Balapattabi K, Bachelor ME, Little JT, Cunningham JT. AT 1a influences GABAA-mediated inhibition through regulation of KCC2 expression. Am J Physiol Regul Integr Comp Physiol 2018; 315:R972-R982. [PMID: 30156863 PMCID: PMC6295501 DOI: 10.1152/ajpregu.00105.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 08/27/2018] [Accepted: 08/27/2018] [Indexed: 11/22/2022]
Abstract
The median preoptic nucleus (MnPO) is an integrative site involved in body fluid homeostasis, cardiovascular control, thermoregulation, and sleep homeostasis. Angiotensin II (ANG II), a neuropeptide shown to have excitatory effects on MnPO neurons, is of particular interest with regard to its role in body fluid homeostasis and cardiovascular control. The present study investigated the role of angiotensin type 1a (AT1a) receptor activation on neuronal excitability in the MnPO. Male Sprague-Dawley rats were infused with an adeno-associated virus with an shRNA against the AT1a receptor or a scrambled control. In vitro loose-patch voltage-clamp recordings of spontaneous action potential activity were made from labeled MnPO neurons in response to brief focal application of ANG II or the GABAA receptor agonist muscimol. Additionally, tissue punches from MnPO were taken to asses mRNA and protein expression. AT1a receptor knockdown neurons were insensitive to ANG II and showed a marked reduction in GABAA-mediated inhibition. The reduction in GABAA-mediated inhibition was not associated with reductions in mRNA or protein expression of GABAA β-subunits. Knockdown of the AT1a receptor was associated with a reduction in the potassium-chloride cotransporter KCC2 mRNA as well as a reduction in pS940 KCC2 protein. The impaired GABAA-mediated inhibition in AT1a knockdown neurons was recovered by bath application of phospholipase C and protein kinase C activators. The following study indicates that AT1a receptor activation mediates the excitability of MnPO neurons, in part, through the regulation of KCC2. The regulation of KCC2 influences the intracellular [Cl-] and the subsequent efficacy of GABAA-mediated currents.
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Affiliation(s)
- George E Farmer
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth , Fort Worth, Texas
| | - Kirthikaa Balapattabi
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth , Fort Worth, Texas
| | - Martha E Bachelor
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth , Fort Worth, Texas
| | - Joel T Little
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth , Fort Worth, Texas
| | - J Thomas Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth , Fort Worth, Texas
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30
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Snyder B, Duong P, Trieu J, Cunningham RL. Androgens modulate chronic intermittent hypoxia effects on brain and behavior. Horm Behav 2018; 106:62-73. [PMID: 30268884 PMCID: PMC6486829 DOI: 10.1016/j.yhbeh.2018.09.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 09/19/2018] [Accepted: 09/25/2018] [Indexed: 12/31/2022]
Abstract
Sleep apnea is associated with testosterone dysregulation as well as increased risk of developing neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD). A rodent model of the hypoxemic events of sleep apnea, chronic intermittent hypoxia (CIH), has been previously documented to impair cognitive function and elevate oxidative stress in male rats, while simultaneously decreasing testosterone. Therefore, androgens may modulate neuronal function under CIH. To investigate the role of androgens during CIH, male rats were assigned to one of four hormone groups: 1) gonadally intact, 2) gonadectomized (GDX), 3) GDX + testosterone (T) supplemented, or 4) GDX + dihydrotestosterone (DHT) supplemented. Each group was exposed to either normal room air or CIH exposure for one week, followed by memory and motor task assessments. Brain regions associated with AD and PD (entorhinal cortex, dorsal hippocampus, and substantia nigra) were examined for oxidative stress and inflammatory markers, key characteristics of AD and PD. Gonadally intact rats exhibited elevated oxidative stress due to CIH, but no significant memory and motor impairments. GDX increased memory impairments, regardless of CIH exposure. T preserved memory function and prevented detrimental CIH-induced changes. In contrast, DHT was not protective, as evidenced by exacerbated oxidative stress under CIH. Further, CIH induced significant spatial memory impairment in rats administered DHT. These results indicate androgens can have both neuroprotective and detrimental effects under CIH, which may have clinical relevance for men with untreated sleep apnea.
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Affiliation(s)
- Brina Snyder
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States of America
| | - Phong Duong
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States of America
| | - Jenny Trieu
- Texas College of Osteopathic Medicine, University of North Texas Health Science Center, Fort Worth, TX, United States of America
| | - Rebecca L Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States of America.
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31
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Oyarce MP, Iturriaga R. Contribution of Oxidative Stress and Inflammation to the Neurogenic Hypertension Induced by Intermittent Hypoxia. Front Physiol 2018; 9:893. [PMID: 30050461 PMCID: PMC6050421 DOI: 10.3389/fphys.2018.00893] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 06/21/2018] [Indexed: 12/11/2022] Open
Abstract
Chronic intermittent hypoxia (CIH), the hallmark of obstructive sleep apnea, is the main risk factor to develop systemic hypertension. Oxidative stress, inflammation, and sympathetic overflow have been proposed as possible mechanisms underlying the CIH-induced hypertension. CIH potentiates the carotid body (CB) chemosensory discharge leading to sympathetic overflow, autonomic dysfunction, and hypertension. Oxidative stress and pro-inflammatory molecules are involved in neurogenic models of hypertension, acting on brainstem and hypothalamic nuclei related to the cardiorespiratory control, such as the nucleus of the solitary tract, which is the primary site for the afferent inputs from the CB. Oxidative stress and pro-inflammatory molecules contribute to the activation of the CB chemoreflex pathway in CIH-induced hypertension. In this brief review, we will discuss new evidence for a critical role of oxidative stress and neuro-inflammation in development of the CIH-induced hypertension through activation of the CB chemoreflex pathway.
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Affiliation(s)
| | - Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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32
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Li T, Chen Y, Gua C, Wu B. Elevated Oxidative Stress and Inflammation in Hypothalamic Paraventricular Nucleus Are Associated With Sympathetic Excitation and Hypertension in Rats Exposed to Chronic Intermittent Hypoxia. Front Physiol 2018; 9:840. [PMID: 30026701 PMCID: PMC6041405 DOI: 10.3389/fphys.2018.00840] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 06/14/2018] [Indexed: 01/08/2023] Open
Abstract
Obstructive sleep apnea (OSA), characterized by recurrent collapse of the upper airway during sleep leading to chronic intermittent hypoxia (CIH), is an independent risk factor for hypertension. Sympathetic excitation has been shown to play a major role in the pathogenesis of OSA-associated hypertension. Accumulating evidence indicates that oxidative stress and inflammation in the hypothalamic paraventricular nucleus (PVN), a critical cardiovascular and autonomic center, mediate sympathetic excitation in many cardiovascular diseases. Here we tested the hypothesis that CIH elevates oxidative stress and inflammation in the PVN, which might be associated with sympathetic excitation and increased blood pressure in a rat model of CIH that mimics the oxygen profile in patients with OSA. Sprague-Dawley rats were pretreated with intracerebroventricular (ICV) infusion of vehicle or superoxide scavenger tempol, and then exposed to control or CIH for 7 days. Compared with control+vehicle rats, CIH+vehicle rats exhibited increased blood pressure, and increased sympathetic drive as indicated by the blood pressure response to ganglionic blockade and plasma norepinephrine levels. Pretreatment with ICV tempol prevented CIH-induced increases in blood pressure and sympathetic drive. Molecular studies revealed that expression of NAD(P)H oxidase subunits, production of reactive oxygen species, expression of proinflammatory cytokines and neuronal excitation in the PVN were elevated in CIH+vehicle rats, compared with control+vehicle rats, but were normalized or reduced in CIH rat pretreated with ICV tempol. Notably, CIH+vehicle rats also had increased systemic oxidative stress and inflammation, which were not altered by ICV tempol. The results suggest that CIH induces elevated oxidative stress and inflammation in the PVN, which lead to PVN neuronal excitation and are associated with sympathetic excitation and increased blood pressure. Central oxidative stress and inflammation may be novel targets for the prevention and treatment of hypertension in patients with OSA.
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Affiliation(s)
- Tiejun Li
- Department of Cardiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Yanli Chen
- Department of Cardiology, The First Hospital of China Medical University, Shenyang, China
| | - Chaojun Gua
- Department of Cardiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Baogang Wu
- Department of Cardiology, Shengjing Hospital of China Medical University, Shenyang, China
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33
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Aczél T, Kun J, Szőke É, Rauch T, Junttila S, Gyenesei A, Bölcskei K, Helyes Z. Transcriptional Alterations in the Trigeminal Ganglia, Nucleus and Peripheral Blood Mononuclear Cells in a Rat Orofacial Pain Model. Front Mol Neurosci 2018; 11:219. [PMID: 29997476 PMCID: PMC6028693 DOI: 10.3389/fnmol.2018.00219] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 06/06/2018] [Indexed: 12/23/2022] Open
Abstract
Orofacial pain and headache disorders are among the most debilitating pain conditions. While the pathophysiological basis of these disorders may be diverse, it is generally accepted that a common mechanism behind the arising pain is the sensitization of extra- and intracranial trigeminal primary afferents. In the present study we investigated gene expression changes in the trigeminal ganglia (TRG), trigeminal nucleus caudalis (TNC) and peripheral blood mononuclear cells (PBMC) evoked by Complete Freund's Adjuvant (CFA)-induced orofacial inflammation in rats, as a model of trigeminal sensitization. Microarray analysis revealed 512 differentially expressed genes between the ipsi- and contralateral TRG samples 7 days after CFA injection. Time-dependent expression changes of G-protein coupled receptor 39 (Gpr39), kisspeptin-1 receptor (Kiss1r), kisspeptin (Kiss1), as well as synaptic plasticity-associated Lkaaear1 (Lkr) and Neurod2 mRNA were described on the basis of qPCR results. The greatest alterations were observed on day 3 ipsilaterally, when orofacial mechanical allodynia reached its maximum. This corresponded well with patterns of neuronal (Fosb), microglia (Iba1), and astrocyte (Gfap) activation markers in both TRG and TNC, and interestingly also in PBMCs. This is the first description of up- and downregulated genes both in primary and secondary sensory neurones of the trigeminovascular system that might play important roles in neuroinflammatory activation mechanisms. We are the first to show transcriptomic alterations in the PBMCs that are similar to the neuronal changes. These results open new perspectives and initiate further investigations in the research of trigeminal pain disorders.
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Affiliation(s)
- Timea Aczél
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary
- Szentágothai Research Centre and Centre for Neuroscience, University of Pécs, Pécs, Hungary
| | - József Kun
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary
- Szentágothai Research Centre and Centre for Neuroscience, University of Pécs, Pécs, Hungary
- MTA-PTE Chronic Pain Research Group, Pécs, Hungary
| | - Éva Szőke
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary
- Szentágothai Research Centre and Centre for Neuroscience, University of Pécs, Pécs, Hungary
- MTA-PTE Chronic Pain Research Group, Pécs, Hungary
| | - Tibor Rauch
- Section of Molecular Medicine, Rush University Medical Center, Chicago, IL, United States
| | - Sini Junttila
- Bioinformatics and Scientific Computing, Vienna Biocenter Core Facilities, Vienna, Austria
| | - Attila Gyenesei
- Szentágothai Research Centre and Centre for Neuroscience, University of Pécs, Pécs, Hungary
- Bioinformatics and Scientific Computing, Vienna Biocenter Core Facilities, Vienna, Austria
| | - Kata Bölcskei
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary
- Szentágothai Research Centre and Centre for Neuroscience, University of Pécs, Pécs, Hungary
| | - Zsuzsanna Helyes
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary
- Szentágothai Research Centre and Centre for Neuroscience, University of Pécs, Pécs, Hungary
- MTA-PTE Chronic Pain Research Group, Pécs, Hungary
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Baum DM, Saussereau M, Jeton F, Planes C, Voituron N, Cardot P, Fiamma MN, Bodineau L. Effect of Gender on Chronic Intermittent Hypoxic Fosb Expression in Cardiorespiratory-Related Brain Structures in Mice. Front Physiol 2018; 9:788. [PMID: 29988603 PMCID: PMC6026892 DOI: 10.3389/fphys.2018.00788] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 06/06/2018] [Indexed: 12/19/2022] Open
Abstract
We aimed to delineate sex-based differences in neuroplasticity that may be associated with previously reported sex-based differences in physiological alterations caused by repetitive succession of hypoxemia-reoxygenation encountered during obstructive sleep apnea (OSA). We examined long-term changes in the activity of brainstem and diencephalic cardiorespiratory neuronal populations induced by chronic intermittent hypoxia (CIH) in male and female mice by analyzing Fosb expression. Whereas the overall baseline and CIH-induced Fosb expression in females was higher than in males, possibly reflecting different neuroplastic dynamics, in contrast, structures responded to CIH by Fosb upregulation in males only. There was a sex-based difference at the level of the rostral ventrolateral reticular nucleus of the medulla, with an increase in the number of FOSB/ΔFOSB-positive cells induced by CIH in males but not females. This structure contains neurons that generate the sympathetic tone and which are involved in CIH-induced sustained hypertension during waking hours. We suggest that the sex-based difference in neuroplasticity of this structure contributes to the reported sex-based difference in CIH-induced hypertension. Moreover, we highlighted a sex-based dimorphic phenomenon in serotoninergic systems induced by CIH, with increased serotoninergic immunoreactivity in the hypoglossal nucleus and a decreased number of serotoninergic cells in the dorsal raphe nucleus in male but not female mice. We suggest that this dimorphism in the neuroplasticity of serotoninergic systems predisposes males to a greater alteration of neuronal control of the upper respiratory tract associated with the greater collapsibility of upper airways described in male OSA subjects.
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Affiliation(s)
- David M Baum
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, UMR-S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
| | - Maud Saussereau
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, UMR-S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
| | - Florine Jeton
- Sorbonne Paris Cité, Université Paris 13, EA2363 Hypoxie et Poumon, Bobigny, France
| | - Carole Planes
- Sorbonne Paris Cité, Université Paris 13, EA2363 Hypoxie et Poumon, Bobigny, France
| | - Nicolas Voituron
- Sorbonne Paris Cité, Université Paris 13, EA2363 Hypoxie et Poumon, Bobigny, France
| | - Philippe Cardot
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, UMR-S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
| | - Marie-Noëlle Fiamma
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, UMR-S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
| | - Laurence Bodineau
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, UMR-S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
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Abstract
PURPOSE OF REVIEW An abnormal heightened carotid body (CB) chemoreflex, which produces autonomic dysfunction and sympathetic overactivation, is the common hallmark of obstructive sleep apnea (OSA), resistant hypertension, systolic heart failure (HF), and cardiometabolic diseases. Accordingly, it has been proposed that the elimination of the CB chemosensory input to the brainstem may reduce the autonomic and cardiorespiratory alterations in sympathetic-associated diseases in humans. RECENT FINDINGS A growing body of evidence obtained in preclinical animal models support that an enhanced CB discharge produces sympathetic hyperactivity, baroreflex sensitivity and heart rate variability impairment, breathing instability, hypertension, and insulin resistance. The elimination CB chemosensory input reduces the sympathetic hyperactivity, the elevated arterial blood pressure in OSA and hypertensive models, abolishes breathing instability and improves animal survival in HF models, and restores insulin tolerance in metabolic models. These results highlight the role played by the enhanced CB drive in the progression of sympathetic-related diseases and support the proposal that the surgical ablation of the CB is useful to restore the autonomic balance and normal cardiorespiratory function in humans. Accordingly, the CB ablation has been used in pilot human studies as a therapeutic treatment for resistant hypertension and HF-induced sympathetic hyperactivity. In this review, I will discuss the supporting evidence for a crucial contribution of the CB in the central autonomic dysfunction and the pros and cons of the CB ablation as a therapy to revert autonomic overactivation. The CB ablation could be a useful method to reverse the enhanced chemoreflex in HF and severe hypertension, but caution is required before extensive use of bilateral CB ablation, which abolished ventilatory responses to hypoxia and may impair baroreceptor function.
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36
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Snyder B, Cunningham RL. Sex differences in sleep apnea and comorbid neurodegenerative diseases. Steroids 2018; 133:28-33. [PMID: 29258810 PMCID: PMC5864541 DOI: 10.1016/j.steroids.2017.12.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 12/05/2017] [Accepted: 12/10/2017] [Indexed: 12/13/2022]
Abstract
Sleep apnea is a disorder, which increasingly affects people worldwide. Whether the associated hypoxic events during sleep are central or obstructive in origin, the end result is excessive daytime sleepiness and an increased risk for several comorbidities, such as cardiovascular and neurodegenerative disorders. Sleep apnea is diagnosed more frequently in men than women, suggesting a role of sex hormones in the pathology of the disease. Furthermore, there are sex differences in the development and progression of comorbid diseases associated with sleep apnea. Therefore, treatment of sleep apnea may be clinically relevant for prevention of subsequent sex-specific comorbid disorders. While the impact sleep apnea has on cardiovascular events has been the subject of many research studies, the role of sleep apnea in neurodegeneration is less established. Here we review known risk factors for sleep apnea and the implications of the observed sex differences in this disease. We also summarize the evidence and mechanisms for how sleep apnea may contribute to the onset of neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease.
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Affiliation(s)
- Brina Snyder
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States
| | - Rebecca L Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States.
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37
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Faulk KE, Nedungadi TP, Cunningham JT. Angiotensin converting enzyme 1 in the median preoptic nucleus contributes to chronic intermittent hypoxia hypertension. Physiol Rep 2018; 5:e13277. [PMID: 28536140 PMCID: PMC5449561 DOI: 10.14814/phy2.13277] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 04/13/2017] [Accepted: 04/17/2017] [Indexed: 02/07/2023] Open
Abstract
Obstructive sleep apnea is associated with hypertension and cardiovascular disease. Chronic intermittent hypoxia is used to model the arterial hypoxemia seen in sleep apnea patients and is associated with increased sympathetic nerve activity and a sustained diurnal increase in blood pressure. The renin angiotensin system has been associated with hypertension seen in chronic intermittent hypoxia. Angiotensin converting enzyme 1, which cleaves angiotensin I to the active counterpart angiotensin II, is present within the central nervous system and has been shown to be regulated by AP‐1 transcription factors, such as ΔFosB. Our previous study suggested that this transcriptional regulation in the median preoptic nucleus contributes to the sustained blood pressure seen following chronic intermittent hypoxia. Viral mediated delivery of a short hairpin RNA against angiotensin converting enzyme 1 in the median preoptic nucleus was used along with radio‐telemetry measurements of blood pressure to test this hypothesis. FosB immunohistochemistry was utilized in order to assess the effects of angiotensin converting enzyme 1 knockdown on the activity of nuclei downstream from median preoptic nucleus. Angiotensin converting enzyme 1 knockdown within median preoptic nucleus significantly attenuated the sustained hypertension seen in chronic intermittent hypoxia. Angiotensin converting enzyme 1 seems to be partly responsible for regulating downstream regions involved in sympathetic and blood pressure control, such as the paraventricular nucleus and the rostral ventrolateral medulla. The data suggest that angiotensin converting enzyme 1 within median preoptic nucleus plays a critical role in the sustained hypertension seen in chronic intermittent hypoxia.
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Affiliation(s)
- Katelynn E Faulk
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Centre at Fort Worth, Fort Worth, Texas
| | - T Prashant Nedungadi
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Centre at Fort Worth, Fort Worth, Texas
| | - J Thomas Cunningham
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Centre at Fort Worth, Fort Worth, Texas
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38
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Snyder B, Shell B, Cunningham JT, Cunningham RL. Chronic intermittent hypoxia induces oxidative stress and inflammation in brain regions associated with early-stage neurodegeneration. Physiol Rep 2018; 5:5/9/e13258. [PMID: 28473320 PMCID: PMC5430123 DOI: 10.14814/phy2.13258] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 03/23/2017] [Indexed: 01/18/2023] Open
Abstract
Sleep apnea is a common comorbidity of neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD). Previous studies have shown an association between elevated oxidative stress and inflammation with severe sleep apnea. Elevated oxidative stress and inflammation are also hallmarks of neurodegenerative diseases. We show increased oxidative stress and inflammation in a manner consistent with early stages of neurodegenerative disease in an animal model of mild sleep apnea. Male rats were exposed to 7 days chronic intermittent hypoxia (CIH) for 8 h/day during the light period. Following CIH, plasma was collected and tested for circulating oxidative stress and inflammatory markers associated with proinflammatory M1 or anti-inflammatory M2 profiles. Tissue punches from brain regions associated with different stages of neurodegenerative diseases (early stage: substantia nigra and entorhinal cortex; intermediate: hippocampus; late stage: rostral ventrolateral medulla and solitary tract nucleus) were also assayed for inflammatory markers. A subset of the samples was examined for 8-hydroxydeoxyguanosine (8-OHdG) expression, a marker of oxidative stress-induced DNA damage. Our results showed increased circulating oxidative stress and inflammation. Furthermore, brain regions associated with early-stage (but not late-stage) AD and PD expressed oxidative stress and inflammatory profiles consistent with reported observations in preclinical neurodegenerative disease populations. These results suggest mild CIH induces key features that are characteristic of early-stage neurodegenerative diseases and may be an effective model to investigate mechanisms contributing to oxidative stress and inflammation in those brain regions.
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Affiliation(s)
- Brina Snyder
- Institute for Health Aging, University of North Texas Health Science Center, Fort Worth, Texas
| | - Brent Shell
- Institute for Cardiovascular and Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas
| | - J Thomas Cunningham
- Institute for Cardiovascular and Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas
| | - Rebecca L Cunningham
- Institute for Health Aging, University of North Texas Health Science Center, Fort Worth, Texas
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39
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Wu Q, Cunningham JT, Mifflin S. Transcription factor ΔFosB acts within the nucleus of the solitary tract to increase mean arterial pressure during exposures to intermittent hypoxia. Am J Physiol Heart Circ Physiol 2017; 314:H270-H277. [PMID: 29101166 DOI: 10.1152/ajpheart.00268.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
ΔFosB is a member of the activator protein-1 family of transcription factors. ΔFosB has low constitutive expression in the central nervous system and is induced after exposure of rodents to intermittent hypoxia (IH), a model of the arterial hypoxemia that accompanies sleep apnea. We hypothesized ΔFosB in the nucleus of the solitary tract (NTS) contributes to increased mean arterial pressure (MAP) during IH. The NTS of 11 male Sprague-Dawley rats was injected (3 sites, 100 nl/site) with a dominant negative construct against ΔFosB (ΔJunD) in an adeno-associated viral vector (AAV)-green fluorescent protein (GFP) reporter. The NTS of 10 rats was injected with AAV-GFP as sham controls. Two weeks after NTS injections, rats were exposed to IH for 8 h/day for 7 days, and MAP was recorded using telemetry. In the sham group, 7 days of IH increased MAP from 99.8 ± 1.1 to 107.3 ± 0.5 mmHg in the day and from 104.4 ± 1.1 to 109.8 ± 0.6 mmHg in the night. In the group that received ΔJunD, IH increased MAP during the day from 95.9 ± 1.7 to 101.3 ± 0.4 mmHg and from 100.9 ± 1.7 to 102.8 ± 0.5 mmHg during the night (both IH-induced changes in MAP were significantly lower than sham, P < 0.05). After injection of the dominant negative construct in the NTS, IH-induced ΔFosB immunoreactivity was decreased in the paraventricular nucleus ( P < 0.05); however, no change was observed in the rostral ventrolateral medulla. These data indicate that ΔFosB within the NTS contributes to the increase in MAP induced by IH exposure. NEW & NOTEWORTHY The results of this study provides new insights into the molecular mechanisms that mediate neuronal adaptations during exposures to intermittent hypoxia, a model of the hypoxemias that occur during sleep apnea. These adaptations are noteworthy as they contribute to the persistent increase in blood pressure induced by exposures to intermittent hypoxia.
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Affiliation(s)
- Qiong Wu
- Departments of Psychiatry and Biobehavioral Sciences and Neurobiology, The Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, California
| | - J Thomas Cunningham
- Institute for Cardiovascular and Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas
| | - Steve Mifflin
- Institute for Cardiovascular and Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas
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40
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Khalyfa A, Kheirandish-Gozal L, Gozal D. Circulating exosomes in obstructive sleep apnea as phenotypic biomarkers and mechanistic messengers of end-organ morbidity. Respir Physiol Neurobiol 2017; 256:143-156. [PMID: 28676332 DOI: 10.1016/j.resp.2017.06.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 06/13/2017] [Accepted: 06/19/2017] [Indexed: 02/08/2023]
Abstract
Obstructive sleep apnea (OSA), the most severe form of sleep disordered breathing, is characterized by intermittent hypoxia during sleep (IH), sleep fragmentation, and episodic hypercapnia. OSA is associated with increased risk for morbidity and mortality affecting cardiovascular, metabolic, and neurocognitive systems, and more recently with non-alcoholic fatty liver disease (NAFLD) and cancer-related deaths. Substantial variability in OSA outcomes suggests that genetically-determined and environmental and lifestyle factors affect the phenotypic susceptibility to OSA. Furthermore, OSA and obesity often co-exist and manifest activation of shared molecular end-organ injury mechanisms that if properly identified may represent potential therapeutic targets. A challenge in the development of non-invasive diagnostic assays in body fluids is the ability to identify clinically relevant biomarkers. Circulating extracellular vesicles (EVs) include a heterogeneous population of vesicular structures including exosomes, prostasomes, microvesicles (MVs), ectosomes and oncosomes, and are classified based on their size, shape and membrane surface composition. Of these, exosomes (30-100nm) are very small membrane vesicles derived from multi-vesicular bodies or from the plasma membrane and play important roles in mediating cell-cell communication via cargo that includes lipids, proteins, mRNAs, miRNAs and DNA. We have recently identified a unique cluster of exosomal miRNAs in both humans and rodents exposed to intermittent hypoxia as well as in patients with OSA with divergent morbid phenotypes. Here we summarize such recent findings, and will focus on exosomal miRNAs in both adult and children which mediate intercellular communication relevant to OSA and endothelial dysfunction, and their potential value as diagnostic and prognostic biomarkers.
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Affiliation(s)
- Abdelnaby Khalyfa
- Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago, Chicago, IL, USA.
| | - Leila Kheirandish-Gozal
- Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago, Chicago, IL, USA
| | - David Gozal
- Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago, Chicago, IL, USA
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42
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Faulk K, Shell B, Nedungadi TP, Cunningham JT. Role of angiotensin-converting enzyme 1 within the median preoptic nucleus following chronic intermittent hypoxia. Am J Physiol Regul Integr Comp Physiol 2017; 312:R245-R252. [PMID: 28003214 PMCID: PMC5336571 DOI: 10.1152/ajpregu.00472.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 12/02/2016] [Accepted: 12/15/2016] [Indexed: 01/08/2023]
Abstract
Sustained hypertension is an important consequence of obstructive sleep apnea. An animal model of the hypoxemia associated with sleep apnea, chronic intermittent hypoxia (CIH), produces increased sympathetic nerve activity (SNA) and sustained increases in blood pressure. Many mechanisms have been implicated in the hypertension associated with CIH, including the role of ΔFosB within the median preoptic nucleus (MnPO). Also, the renin-angiotensin system (RAS) has been associated with CIH hypertension. We conducted experiments to determine the possible association of FosB/ΔFosB with a RAS component, angiotensin-converting enzyme 1 (ACE1), within the MnPO following 7 days of CIH. Retrograde tract tracing from the paraventricular nucleus (PVN), a downstream region of the MnPO, was used to establish a potential pathway for FosB/ΔFosB activation of MnPO ACE1 neurons. After CIH, ACE1 cells with FosB/ΔFosB expression increased colocalization with a retrograde tracer that was injected unilaterally within the PVN. Also, Western blot examination showed ACE1 protein expression increasing within the MnPO following CIH. Chromatin immunoprecipitation (ChIP) assays demonstrated an increase in FosB/ΔFosB association with the ACE1 gene within the MnPO following CIH. FosB/ΔFosB may transcriptionally target ACE1 within the MnPO following CIH to affect the downstream PVN region, which may influence SNA and blood pressure.
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Affiliation(s)
- Katelynn Faulk
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas; and
| | - Brent Shell
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas; and
| | - T Prashant Nedungadi
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas; and
- American Heart Association, Dallas, Texas
| | - J Thomas Cunningham
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas; and
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Taylor KS, Murai H, Millar PJ, Haruki N, Kimmerly DS, Morris BL, Tomlinson G, Bradley TD, Floras JS. Arousal From Sleep and Sympathetic Excitation During Wakefulness. Hypertension 2016; 68:1467-1474. [DOI: 10.1161/hypertensionaha.116.08212] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 08/05/2016] [Accepted: 09/11/2016] [Indexed: 02/07/2023]
Abstract
Obstructive apnea during sleep elevates the set point for efferent sympathetic outflow during wakefulness. Such resetting is attributed to hypoxia-induced upregulation of peripheral chemoreceptor and brain stem sympathetic function. Whether recurrent arousal from sleep also influences daytime muscle sympathetic nerve activity is unknown. We therefore tested, in a cohort of 48 primarily nonsleepy, middle-aged, male (30) and female (18) volunteers (age: 59±1 years, mean±SE), the hypothesis that the frequency of arousals from sleep (arousal index) would relate to daytime muscle sympathetic burst incidence, independently of the frequency of apnea or its severity. Polysomnography identified 24 as having either no or mild obstructive sleep apnea (apnea–hypopnea index <15 events/h) and 24 with moderate-to-severe obstructive sleep apnea (apnea–hypopnea index >15 events/h). Burst incidence correlated significantly with arousal index (
r
=0.53;
P
<0.001), minimum oxygen saturation (
r
=−0.43;
P
=0.002), apnea–hypopnea index (
r
=0.41;
P
=0.004), age (
r
=0.36;
P
=0.013), and body mass index (
r
=0.33;
P
=0.022) but not with oxygen desaturation index (
r
=0.28;
P
=0.056). Arousal index was the single strongest predictor of muscle sympathetic nerve activity burst incidence, present in all best subsets regression models. The model with the highest adjusted
R
2
(0.456) incorporated arousal index, minimum oxygen saturation, age, body mass index, and oxygen desaturation index but not apnea–hypopnea index. An apnea- and hypoxia-independent effect of sleep fragmentation on sympathetic discharge during wakefulness could contribute to intersubject variability, age-related increases in muscle sympathetic nerve activity, associations between sleep deprivation and insulin resistance or insomnia and future cardiovascular events, and residual adrenergic risk with persistence of hypertension should therapy eliminate obstructive apneas but not arousals.
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Affiliation(s)
- Keri S. Taylor
- From the University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Ontario, Canada
| | - Hisayoshi Murai
- From the University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Ontario, Canada
| | - Philip J. Millar
- From the University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Ontario, Canada
| | - Nobuhiko Haruki
- From the University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Ontario, Canada
| | - Derek S. Kimmerly
- From the University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Ontario, Canada
| | - Beverley L. Morris
- From the University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Ontario, Canada
| | - George Tomlinson
- From the University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Ontario, Canada
| | - T. Douglas Bradley
- From the University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Ontario, Canada
| | - John S. Floras
- From the University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Ontario, Canada
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Kubin L. Neural Control of the Upper Airway: Respiratory and State-Dependent Mechanisms. Compr Physiol 2016; 6:1801-1850. [PMID: 27783860 DOI: 10.1002/cphy.c160002] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Upper airway muscles subserve many essential for survival orofacial behaviors, including their important role as accessory respiratory muscles. In the face of certain predisposition of craniofacial anatomy, both tonic and phasic inspiratory activation of upper airway muscles is necessary to protect the upper airway against collapse. This protective action is adequate during wakefulness, but fails during sleep which results in recurrent episodes of hypopneas and apneas, a condition known as the obstructive sleep apnea syndrome (OSA). Although OSA is almost exclusively a human disorder, animal models help unveil the basic principles governing the impact of sleep on breathing and upper airway muscle activity. This article discusses the neuroanatomy, neurochemistry, and neurophysiology of the different neuronal systems whose activity changes with sleep-wake states, such as the noradrenergic, serotonergic, cholinergic, orexinergic, histaminergic, GABAergic and glycinergic, and their impact on central respiratory neurons and upper airway motoneurons. Observations of the interactions between sleep-wake states and upper airway muscles in healthy humans and OSA patients are related to findings from animal models with normal upper airway, and various animal models of OSA, including the chronic-intermittent hypoxia model. Using a framework of upper airway motoneurons being under concurrent influence of central respiratory, reflex and state-dependent inputs, different neurotransmitters, and neuropeptides are considered as either causing a sleep-dependent withdrawal of excitation from motoneurons or mediating an active, sleep-related inhibition of motoneurons. Information about the neurochemistry of state-dependent control of upper airway muscles accumulated to date reveals fundamental principles and may help understand and treat OSA. © 2016 American Physiological Society. Compr Physiol 6:1801-1850, 2016.
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Affiliation(s)
- Leszek Kubin
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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45
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Imbe H, Kimura A. Repeated forced swim stress affects the expression of pCREB and ΔFosB and the acetylation of histone H3 in the rostral ventromedial medulla and locus coeruleus. Brain Res Bull 2016; 127:11-22. [PMID: 27530066 DOI: 10.1016/j.brainresbull.2016.08.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Revised: 08/10/2016] [Accepted: 08/11/2016] [Indexed: 01/31/2023]
Abstract
The rostral ventromedial medulla (RVM) and locus coeruleus (LC) play crucial roles in descending pain modulation system. In the present study we examined the expression of phospho-cAMP response element-binding protein (pCREB) and ΔFosB and the acetylation of histone H3 in the RVM and LC after forced swim stress (FS) and complete Freund's adjuvant (CFA) injection to clarify changes in descending pain modulatory system in a rat model of stress-induced hyperalgesia. FS (day 1, 10min; days 2-3, 20min) induced a significant increase in the expression of pCREB and ΔFosB and the acetylation of histone H3 in the RVM, whereas the FS induced a significant increase only in the acetylation of histone H3 in the LC. CFA injection into the hindpaw did not induce a significant change in those expression and acetylation. Quantitative image analysis demonstrated that the numbers of pCREB-, acetylated histone H3- and ΔFosB-IR cells in the RVM were significantly higher in the FS group than those in the naive group. The CFA injection after the FS did not affect the FS-induced increases in the expression of pCREB and ΔFosB and the acetylation of histone H3 in the RVM even though nullified the increase in the acetylation of histone H3 in the LC. These findings suggest different neuroplasticities between the RVM and LC after the FS, which may be involved in activity change of descending pain modulatory system after the CFA injection.
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Affiliation(s)
- Hiroki Imbe
- Department of Physiology, Wakayama Medical University, Kimiidera 811-1, Wakayama City, 641-8509, Japan.
| | - Akihisa Kimura
- Department of Physiology, Wakayama Medical University, Kimiidera 811-1, Wakayama City, 641-8509, Japan
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Dyavanapalli J, Dergacheva O, Wang X, Mendelowitz D. Parasympathetic Vagal Control of Cardiac Function. Curr Hypertens Rep 2016; 18:22. [PMID: 26849575 DOI: 10.1007/s11906-016-0630-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
This brief review focuses on four new topics, with novel and clinically significant consequences, concerning the powerful influence of parasympathetic activity on cardiac function. In this short summary, we will highlight very recent and important work, published in the last 3-4 years, that (1) challenges the paradigm that parasympathetic activity to the heart is involved in the control of heart rate but plays little role in other cardiac functions, (2) characterizes important long-range synaptic pathways to parasympathetic cardiac vagal neurons that are involved in "higher" brain functions (such as arousal and emotional challenges), (3) asks whether implantable chronic vagal nerve stimulation is a promising clinical tool for treating cardiovascular diseases, and (4) describes newly identified neuropeptides and other modulators that can influence the generation and maintenance of parasympathetic activity to the heart.
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Affiliation(s)
- Jhansi Dyavanapalli
- Department of Pharmacology and Physiology, The George Washington University, 2300 Eye St NW, Washington, DC, 20037, USA
| | - Olga Dergacheva
- Department of Pharmacology and Physiology, The George Washington University, 2300 Eye St NW, Washington, DC, 20037, USA
| | - Xin Wang
- Department of Pharmacology and Physiology, The George Washington University, 2300 Eye St NW, Washington, DC, 20037, USA
| | - David Mendelowitz
- Department of Pharmacology and Physiology, The George Washington University, 2300 Eye St NW, Washington, DC, 20037, USA.
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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: 48] [Impact Index Per Article: 6.0] [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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Henderson LA, Fatouleh RH, Lundblad LC, McKenzie DK, Macefield VG. Effects of 12 Months Continuous Positive Airway Pressure on Sympathetic Activity Related Brainstem Function and Structure in Obstructive Sleep Apnea. Front Neurosci 2016; 10:90. [PMID: 27013952 PMCID: PMC4785184 DOI: 10.3389/fnins.2016.00090] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 02/22/2016] [Indexed: 12/21/2022] Open
Abstract
Muscle sympathetic nerve activity (MSNA) is greatly elevated in patients with obstructive sleep apnea (OSA) during normoxic daytime wakefulness. Increased MSNA is a precursor to hypertension and elevated cardiovascular morbidity and mortality. However, the mechanisms underlying the high MSNA in OSA are not well understood. In this study we used concurrent microneurography and magnetic resonance imaging to explore MSNA-related brainstem activity changes and anatomical changes in 15 control and 15 OSA subjects before and after 6 and 12 months of continuous positive airway pressure (CPAP) treatment. We found that following 6 and 12 months of CPAP treatment, resting MSNA levels were significantly reduced in individuals with OSA. Furthermore, this MSNA reduction was associated with restoration of MSNA-related brainstem activity and structural changes in the medullary raphe, rostral ventrolateral medulla, dorsolateral pons, and ventral midbrain. This restoration occurred after 6 months of CPAP treatment and was maintained following 12 months CPAP. These findings show that continual CPAP treatment is an effective long-term treatment for elevated MSNA likely due to its effects on restoring brainstem structure and function.
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Affiliation(s)
- Luke A Henderson
- Neural Imaging Laboratory, Discipline of Anatomy and Histology, The University of Sydney Sydney, NSW, Australia
| | - Rania H Fatouleh
- School of Medicine, Western Sydney University Sydney, NSW, Australia
| | - Linda C Lundblad
- Neural Imaging Laboratory, Discipline of Anatomy and Histology, The University of SydneySydney, NSW, Australia; School of Medicine, Western Sydney UniversitySydney, NSW, Australia
| | - David K McKenzie
- Department of Respiratory Medicine, Prince of Wales Private Hospital Sydney, NSW, Australia
| | - Vaughan G Macefield
- School of Medicine, Western Sydney UniversitySydney, NSW, Australia; Neuroscience Research AustraliaSydney, NSW, Australia
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50
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Ding Y, Hou X, Chen L, Zhou H, Gong Y, Dai L, Zheng Y. Heme oxygenase-1 dependant pathway contributes to protection by tetramethylpyrazine against chronic hypoxic injury on medulla oblongata in rats. J Neurol Sci 2016; 361:101-11. [DOI: 10.1016/j.jns.2015.12.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 12/12/2015] [Accepted: 12/15/2015] [Indexed: 10/22/2022]
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