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Vaz JR, Silva LM, Stergiou N. Stride-to-Stride Fluctuations of Human Gait Are Affected By Chronobiology: An Exploratory Study. Adv Biol (Weinh) 2023; 7:e2200235. [PMID: 36658787 PMCID: PMC10354220 DOI: 10.1002/adbi.202200235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 12/27/2022] [Indexed: 01/21/2023]
Abstract
Physiological processes present daily oscillations of ≈24 h, called circadian rhythms. Motor performance, for example, reaches its peak in the afternoon, although this can be affected by chronotype. Certain motor activities, for example, walking, can also be affected by circadian rhythms. Healthy walking exhibits stride-to-stride fluctuations with a fractal-like structure that enables adaptability. While pathology and aging are shown to lead to random-like fluctuations; and, therefore, decreased adaptability; the influence of circadian rhythms remains unknown. This study investigates how these fluctuations present in healthy gait are affected by the time of day and chronotype. Eighteen young adults walk for 10 min every 2 h, from 8 a.m. to 6 p.m. Footswitches are used to determine heel-strike and calculate stride time. Then, detrended fluctuation analysis is used to calculate fractal scaling. A mixed-model Analysis of Variance is used and followed by a backward stepwise elimination process. Tukey's tests are used for pairwise comparisons. The statistical model shows the effect of time during the day (12 p.m. exhibits a higher fractal scaling compared to 8 a.m.); and chronotype (evening-types exhibit higher fractal scaling compared to morning-types). This study reveals the influence of chronobiology on stride-to-stride fluctuations. These findings open new perspectives to integrate circadian medicine in biomechanics.
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Affiliation(s)
- João R. Vaz
- Egas Moniz School of Health & Science, Egas Moniz Interdisciplinary Research Centre, Monte de Caparica, Almada
- Division of Biomechanics and Research Development and Center for Research in Human Movement Variability, University of Nebraska at Omaha, 6160 University Drive, Omaha, NE 68182-0860, USA
| | - Luís M. Silva
- Division of Biomechanics and Research Development and Center for Research in Human Movement Variability, University of Nebraska at Omaha, 6160 University Drive, Omaha, NE 68182-0860, USA
- Libphys – NOVA School of Science and Technology, Universidade Nova de Lisboa, Almada, Portugal
| | - Nick Stergiou
- Division of Biomechanics and Research Development and Center for Research in Human Movement Variability, University of Nebraska at Omaha, 6160 University Drive, Omaha, NE 68182-0860, USA
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2
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Cincotta AH. Brain Dopamine-Clock Interactions Regulate Cardiometabolic Physiology: Mechanisms of the Observed Cardioprotective Effects of Circadian-Timed Bromocriptine-QR Therapy in Type 2 Diabetes Subjects. Int J Mol Sci 2023; 24:13255. [PMID: 37686060 PMCID: PMC10487918 DOI: 10.3390/ijms241713255] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/19/2023] [Accepted: 07/27/2023] [Indexed: 09/10/2023] Open
Abstract
Despite enormous global efforts within clinical research and medical practice to reduce cardiovascular disease(s) (CVD), it still remains the leading cause of death worldwide. While genetic factors clearly contribute to CVD etiology, the preponderance of epidemiological data indicate that a major common denominator among diverse ethnic populations from around the world contributing to CVD is the composite of Western lifestyle cofactors, particularly Western diets (high saturated fat/simple sugar [particularly high fructose and sucrose and to a lesser extent glucose] diets), psychosocial stress, depression, and altered sleep/wake architecture. Such Western lifestyle cofactors are potent drivers for the increased risk of metabolic syndrome and its attendant downstream CVD. The central nervous system (CNS) evolved to respond to and anticipate changes in the external (and internal) environment to adapt survival mechanisms to perceived stresses (challenges to normal biological function), including the aforementioned Western lifestyle cofactors. Within the CNS of vertebrates in the wild, the biological clock circuitry surveils the environment and has evolved mechanisms for the induction of the obese, insulin-resistant state as a survival mechanism against an anticipated ensuing season of low/no food availability. The peripheral tissues utilize fat as an energy source under muscle insulin resistance, while increased hepatic insulin resistance more readily supplies glucose to the brain. This neural clock function also orchestrates the reversal of the obese, insulin-resistant condition when the low food availability season ends. The circadian neural network that produces these seasonal shifts in metabolism is also responsive to Western lifestyle stressors that drive the CNS clock into survival mode. A major component of this natural or Western lifestyle stressor-induced CNS clock neurophysiological shift potentiating the obese, insulin-resistant state is a diminution of the circadian peak of dopaminergic input activity to the pacemaker clock center, suprachiasmatic nucleus. Pharmacologically preventing this loss of circadian peak dopaminergic activity both prevents and reverses existing metabolic syndrome in a wide variety of animal models of the disorder, including high fat-fed animals. Clinically, across a variety of different study designs, circadian-timed bromocriptine-QR (quick release) (a unique formulation of micronized bromocriptine-a dopamine D2 receptor agonist) therapy of type 2 diabetes subjects improved hyperglycemia, hyperlipidemia, hypertension, immune sterile inflammation, and/or adverse cardiovascular event rate. The present review details the seminal circadian science investigations delineating important roles for CNS circadian peak dopaminergic activity in the regulation of peripheral fuel metabolism and cardiovascular biology and also summarizes the clinical study findings of bromocriptine-QR therapy on cardiometabolic outcomes in type 2 diabetes subjects.
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Ragozzino FJ, Peterson B, Karatsoreos IN, Peters JH. Circadian regulation of glutamate release pathways shapes synaptic throughput in the brainstem nucleus of the solitary tract (NTS). J Physiol 2023; 601:1881-1896. [PMID: 36975145 PMCID: PMC10192157 DOI: 10.1113/jp284370] [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: 01/12/2023] [Accepted: 03/06/2023] [Indexed: 03/29/2023] Open
Abstract
Circadian regulation of autonomic reflex pathways pairs physiological function with the daily light cycle. The brainstem nucleus of the solitary tract (NTS) is a key candidate for rhythmic control of the autonomic nervous system. Here we investigated circadian regulation of NTS neurotransmission and synaptic throughput using patch-clamp electrophysiology in brainstem slices from mice. We found that spontaneous quantal glutamate release onto NTS neurons showed strong circadian rhythmicity, with the highest rate of release during the light phase and the lowest in the dark, that were sufficient to drive day/night differences in constitutive postsynaptic action potential firing. In contrast, afferent evoked action potential throughput was enhanced during the dark and diminished in the light. Afferent-driven synchronous release pathways showed a similar decrease in release probability that did not explain the enhanced synaptic throughput during the night. However, analysis of postsynaptic membrane properties revealed diurnal changes in conductance, which, when coupled with the circadian changes in glutamate release pathways, tuned synaptic throughput between the light and dark phases. These coordinated pre-/postsynaptic changes encode nuanced control over synaptic performance and pair NTS action potential firing and vagal throughput with time of day. KEY POINTS: Vagal afferent neurons relay information from peripheral organs to the brainstem nucleus of the solitary tract (NTS) to initiate autonomic reflex pathways as well as providing important controls of food intake, digestive function and energy balance. Vagally mediated reflexes and behaviours are under strong circadian regulation. Diurnal fluctuations in presynaptic vesicle release pathways and postsynaptic membrane conductances provide nuanced control over NTS action potential firing and vagal synaptic throughput. Coordinated pre-/postsynaptic changes represent a fundamental mechanism mediating daily changes in vagal afferent signalling and autonomic function.
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Affiliation(s)
- Forrest J. Ragozzino
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, WA, USA
| | - BreeAnne Peterson
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, WA, USA
| | - Ilia N. Karatsoreos
- Department of Psychological and Brain Sciences, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - James H. Peters
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, WA, USA
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4
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Grosu GF, Hopp AV, Moca VV, Bârzan H, Ciuparu A, Ercsey-Ravasz M, Winkel M, Linde H, Mureșan RC. The fractal brain: scale-invariance in structure and dynamics. Cereb Cortex 2023; 33:4574-4605. [PMID: 36156074 PMCID: PMC10110456 DOI: 10.1093/cercor/bhac363] [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: 06/02/2022] [Revised: 08/09/2022] [Accepted: 08/10/2022] [Indexed: 11/12/2022] Open
Abstract
The past 40 years have witnessed extensive research on fractal structure and scale-free dynamics in the brain. Although considerable progress has been made, a comprehensive picture has yet to emerge, and needs further linking to a mechanistic account of brain function. Here, we review these concepts, connecting observations across different levels of organization, from both a structural and functional perspective. We argue that, paradoxically, the level of cortical circuits is the least understood from a structural point of view and perhaps the best studied from a dynamical one. We further link observations about scale-freeness and fractality with evidence that the environment provides constraints that may explain the usefulness of fractal structure and scale-free dynamics in the brain. Moreover, we discuss evidence that behavior exhibits scale-free properties, likely emerging from similarly organized brain dynamics, enabling an organism to thrive in an environment that shares the same organizational principles. Finally, we review the sparse evidence for and try to speculate on the functional consequences of fractality and scale-freeness for brain computation. These properties may endow the brain with computational capabilities that transcend current models of neural computation and could hold the key to unraveling how the brain constructs percepts and generates behavior.
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Affiliation(s)
- George F Grosu
- Department of Experimental and Theoretical Neuroscience, Transylvanian Institute of Neuroscience, Str. Ploiesti 33, 400157 Cluj-Napoca, Romania
- Faculty of Electronics, Telecommunications and Information Technology, Technical University of Cluj-Napoca, Str. Memorandumului 28, 400114 Cluj-Napoca, Romania
| | | | - Vasile V Moca
- Department of Experimental and Theoretical Neuroscience, Transylvanian Institute of Neuroscience, Str. Ploiesti 33, 400157 Cluj-Napoca, Romania
| | - Harald Bârzan
- Department of Experimental and Theoretical Neuroscience, Transylvanian Institute of Neuroscience, Str. Ploiesti 33, 400157 Cluj-Napoca, Romania
- Faculty of Electronics, Telecommunications and Information Technology, Technical University of Cluj-Napoca, Str. Memorandumului 28, 400114 Cluj-Napoca, Romania
| | - Andrei Ciuparu
- Department of Experimental and Theoretical Neuroscience, Transylvanian Institute of Neuroscience, Str. Ploiesti 33, 400157 Cluj-Napoca, Romania
- Faculty of Electronics, Telecommunications and Information Technology, Technical University of Cluj-Napoca, Str. Memorandumului 28, 400114 Cluj-Napoca, Romania
| | - Maria Ercsey-Ravasz
- Department of Experimental and Theoretical Neuroscience, Transylvanian Institute of Neuroscience, Str. Ploiesti 33, 400157 Cluj-Napoca, Romania
- Faculty of Physics, Babes-Bolyai University, Str. Mihail Kogalniceanu 1, 400084 Cluj-Napoca, Romania
| | - Mathias Winkel
- Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Helmut Linde
- Department of Experimental and Theoretical Neuroscience, Transylvanian Institute of Neuroscience, Str. Ploiesti 33, 400157 Cluj-Napoca, Romania
- Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Raul C Mureșan
- Department of Experimental and Theoretical Neuroscience, Transylvanian Institute of Neuroscience, Str. Ploiesti 33, 400157 Cluj-Napoca, Romania
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Smets H, Stumpp L, Chavez J, Cury J, Vande Perre L, Doguet P, Vanhoestenberghe A, Delbeke J, El Tahry R, Nonclercq A. Chronic recording of the vagus nerve to analyze modulations by the light-dark cycle. J Neural Eng 2022; 19. [PMID: 35764074 DOI: 10.1088/1741-2552/ac7c8f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 06/28/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVE The vagus nerve is considered to play a key role in the circadian rhythm. Chronic continuous analysis of the vagus nerve activity could contribute to a better understanding of the role of the vagus nerve in light-dark modulations. This paper presents a continuous analysis of spontaneous vagus nerve activity performed in four rats. APPROACH We analyzed the vagus electroneurogram (VENG) and electroencephalogram (EEG) over a recording period of 28 days. Spike activity and heart rate estimation were derived from the VENG, and slow-wave activity was derived from the EEG. The presence of repetitive patterns was investigated with periodograms, cosinor fitting, autocorrelation, and statistical tests. The light-dark variations derived from the VENG spikes were compared with EEG slow waves, an established metric in circadian studies. RESULTS Our results demonstrate that light-dark variations can be detected in long-term vagus nerve activity monitoring. A recording period of about seven days is required to characterize accurately the VENG light-dark variations. SIGNIFICANCE As a major outcome of this study, vagus nerve recordings hold the promise to help understand circadian regulation.
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Affiliation(s)
- Hugo Smets
- BEAMS, Université Libre de Bruxelles Faculté des sciences appliquées/Ecole polytechnique, Avenue Franklin Roosevelt, 50, CP 165/56, Bruxelles, 1050, BELGIUM
| | - Lars Stumpp
- IONS, Université catholique de Louvain, Avenue Mounier 53/B1.53.05, Brussels, 1200, BELGIUM
| | - Javier Chavez
- BEAMS, Université Libre de Bruxelles Faculté des sciences appliquées/Ecole polytechnique, Avenue Franklin Roosevelt, 50, CP 165/56, Bruxelles, 1050, BELGIUM
| | - Joaquin Cury
- BEAMS, Université Libre de Bruxelles Faculté des sciences appliquées/Ecole polytechnique, Avenue Franklin Roosevelt, 50, CP 165/56, Bruxelles, 1050, BELGIUM
| | - Louis Vande Perre
- BEAMS, Université Libre de Bruxelles Faculté des sciences appliquées/Ecole polytechnique, Avenue Franklin Roosevelt, 50, CP 165/56, Bruxelles, 1050, BELGIUM
| | - Pascal Doguet
- Synergia Medical SA, Rue Emile Francqui 6, Mont-Saint-Guibert, 1435, BELGIUM
| | - Anne Vanhoestenberghe
- Aspire Centre for Rehabilitation Engineering and Assistive Technology, University College London, Brockley Hill, Aspire Create - IOMS BUilding, RNOH campus, London, HA74LP, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Jean Delbeke
- Private Address - Belgium, Seringenstraat 27, Kraainem, B-1950, BELGIUM
| | - Riëm El Tahry
- IONS, Université catholique de Louvain, Avenue Mounier 53/B1.53.05, Brussels, 1200, BELGIUM
| | - Antoine Nonclercq
- BEAMS, Université Libre de Bruxelles Faculté des sciences appliquées/Ecole polytechnique, Avenue Franklin Roosevelt, 50, CP 165/56, Bruxelles, 1050, BELGIUM
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Abstract
An environmental enrichment (EE) cage consisting of a broad living area and various stimulators triggers social, cognitive, and physical activities. EE has been utilized in a wide range of neurological and non-neurological studies. However, the details of the environmental enrichment protocol were not well described in these studies. This has resulted in uncertainty and inconsistency in methodology, which may thus fail to replicate environmental enrichment effects, influencing the study outcome. Here we describe the basic guidelines and present an easy-to-follow protocol for environmental enrichment in rat models. © 2021 Wiley Periodicals LLC. Basic Protocol: Environmental enrichment housing.
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Affiliation(s)
- Teh Rasyidah Ismail
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Selangor Darul Ehsan, Malaysia.,Clinical Laboratory Science Section, Institute of Medical Science Technology, Universiti Kuala Lumpur, Kajang, Selangor Darul Ehsan, Malaysia
| | - Christina Gertrude Yap
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Rakesh Naidu
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Narendra Pamidi
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Selangor Darul Ehsan, Malaysia
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Abstract
PURPOSE OF REVIEW The endogenous circadian rhythms are one of the cardinal processes that control sleep. They are self-sustaining biological rhythms with a periodicity of approximately 24 hours that may be entrained by external zeitgebers (German for time givers), such as light, exercise, and meal times. This article discusses the physiology of the circadian rhythms, their relationship to neurologic disease, and the presentation and treatment of circadian rhythm sleep-wake disorders. RECENT FINDINGS Classic examples of circadian rhythms include cortisol and melatonin secretion, body temperature, and urine volume. More recently, the impact of circadian rhythm on several neurologic disorders has been investigated, such as the timing of occurrence of epileptic seizures as well as neurobehavioral functioning in dementia. Further updates include a more in-depth understanding of the symptoms, consequences, and treatment of circadian sleep-wake disorders, which may occur because of extrinsic misalignment with clock time or because of intrinsic dysfunction of the brain. An example of extrinsic misalignment occurs with jet lag during transmeridian travel or with intrinsic circadian rhythm sleep-wake disorders such as advanced or delayed sleep-wake phase disorders. In advanced sleep-wake phase disorder, which is most common in elderly individuals, sleep onset and morning arousal are undesirably early, leading to impaired evening function with excessive sleepiness and sleep-maintenance insomnia with early morning awakening. By contrast, delayed sleep-wake phase disorder is characterized by an inability to initiate sleep before the early morning hours, with subsequent delayed rise time, leading to clinical symptoms of severe sleep-onset insomnia coupled with excessive daytime sleepiness in the morning hours, as patients are unable to "sleep in" to attain sufficient sleep quantity. Irregular sleep-wake rhythm disorder is misentrainment with patches of brief sleep and wakefulness spread throughout the day, leading to unstable sleep and waking behavioral patterns and an entirely idiosyncratic sleep-wake schedule. SUMMARY Familiarity with these major circadian rhythm sleep-wake disorder phenotypes and their overlap with other neurologic disorders is essential for the neurologist so that clinicians may intervene and improve patient functioning and quality of life.
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Hsieh PN, Zhang L, Jain MK. Coordination of cardiac rhythmic output and circadian metabolic regulation in the heart. Cell Mol Life Sci 2018; 75:403-416. [PMID: 28825119 PMCID: PMC5765194 DOI: 10.1007/s00018-017-2606-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 07/13/2017] [Accepted: 08/02/2017] [Indexed: 02/07/2023]
Abstract
Over the course of a 24-h day, demand on the heart rises and falls with the sleep/wake cycles of the organism. Cardiac metabolism oscillates appropriately, with the relative contributions of major energy sources changing in a circadian fashion. The cardiac peripheral clock is hypothesized to drive many of these changes, yet the precise mechanisms linking the cardiac clock to metabolism remain a source of intense investigation. Here we summarize the current understanding of circadian alterations in cardiac metabolism and physiology, with an emphasis on novel findings from unbiased transcriptomic studies. Additionally, we describe progress in elucidating the links between the cardiac peripheral clock outputs and cardiac metabolism, as well as their implications for cardiac physiology.
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Affiliation(s)
- Paishiun Nelson Hsieh
- Department of Medicine, Case Cardiovascular Research Institute, Case Western Reserve University, 2103 Cornell Road, Room 4-503, Cleveland, OH, USA
- Harrington Heart and Vascular Institute, University Hospitals Case Medical Center, Cleveland, OH, USA
- Department of Pathology, Case Western Reserve University, Cleveland, OH, USA
| | - Lilei Zhang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Mukesh Kumar Jain
- Department of Medicine, Case Cardiovascular Research Institute, Case Western Reserve University, 2103 Cornell Road, Room 4-503, Cleveland, OH, USA.
- Harrington Heart and Vascular Institute, University Hospitals Case Medical Center, Cleveland, OH, USA.
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9
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West AC, Smith L, Ray DW, Loudon ASI, Brown TM, Bechtold DA. Misalignment with the external light environment drives metabolic and cardiac dysfunction. Nat Commun 2017; 8:417. [PMID: 28900189 PMCID: PMC5595905 DOI: 10.1038/s41467-017-00462-2] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 06/30/2017] [Indexed: 12/20/2022] Open
Abstract
Most organisms use internal biological clocks to match behavioural and physiological processes to specific phases of the day-night cycle. Central to this is the synchronisation of internal processes across multiple organ systems. Environmental desynchrony (e.g. shift work) profoundly impacts human health, increasing cardiovascular disease and diabetes risk, yet the underlying mechanisms remain unclear. Here, we characterise the impact of desynchrony between the internal clock and the external light-dark (LD) cycle on mammalian physiology. We reveal that even under stable LD environments, phase misalignment has a profound effect, with decreased metabolic efficiency and disrupted cardiac function including prolonged QT interval duration. Importantly, physiological dysfunction is not driven by disrupted core clock function, nor by an internal desynchrony between organs, but rather the altered phase relationship between the internal clockwork and the external environment. We suggest phase misalignment as a major driver of pathologies associated with shift work, chronotype and social jetlag.The misalignment between internal circadian rhythm and the day-night cycle can be caused by genetic, behavioural and environmental factors, and may have a profound impact on human physiology. Here West et al. show that desynchrony between the internal clock and the external environment alter metabolic parameters and cardiac function in mice.
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Affiliation(s)
- Alexander C West
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PL, UK
| | - Laura Smith
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PL, UK
| | - David W Ray
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PL, UK
| | - Andrew S I Loudon
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PL, UK
| | - Timothy M Brown
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PL, UK
| | - David A Bechtold
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PL, UK.
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10
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Shifts in the light-dark cycle increase unpredictability of the cardiovascular system. Auton Neurosci 2017; 206:51-59. [DOI: 10.1016/j.autneu.2017.07.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 07/24/2017] [Accepted: 07/25/2017] [Indexed: 12/21/2022]
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11
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Braeutigam S. Invited Frontiers Commentary. Tier Climbing Article: Redefining Neuromarketing as an Integrated Science of Influence. Front Neurosci 2017; 11:22. [PMID: 28184186 PMCID: PMC5266867 DOI: 10.3389/fnins.2017.00022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 01/11/2017] [Indexed: 11/20/2022] Open
Affiliation(s)
- Sven Braeutigam
- Department of Psychiatry, Oxford Centre for Human Brain Activity, University of Oxford Oxford, UK
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12
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Yaniv Y, Lakatta EG. The end effector of circadian heart rate variation: the sinoatrial node pacemaker cell. BMB Rep 2016; 48:677-84. [PMID: 25999176 PMCID: PMC4791323 DOI: 10.5483/bmbrep.2015.48.12.061] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Indexed: 12/16/2022] Open
Abstract
Cardiovascular function is regulated by the rhythmicity of circadian, infradian and ultradian clocks. Specific time scales of different cell types drive their functions: circadian gene regulation at hours scale, activation-inactivation cycles of ion channels at millisecond scales, the heart's beating rate at hundreds of millisecond scales, and low frequency autonomic signaling at cycles of tens of seconds. Heart rate and rhythm are modulated by a hierarchical clock system: autonomic signaling from the brain releases neurotransmitters from the vagus and sympathetic nerves to the heart’s pacemaker cells and activate receptors on the cell. These receptors activating ultradian clock functions embedded within pacemaker cells include sarcoplasmic reticulum rhythmic spontaneous Ca2+ cycling, rhythmic ion channel current activation and inactivation, and rhythmic oscillatory mitochondria ATP production. Here we summarize the evidence that intrinsic pacemaker cell mechanisms are the end effector of the hierarchical brain-heart circadian clock system. [BMB Reports 2015; 48(12): 677-684]
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Affiliation(s)
- Yael Yaniv
- Biomedical Engineering Faculty, Technion-IIT, Haifa, Israel
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, Biomedical Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, Maryland, USA
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13
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Lo MT, Chiang WY, Hsieh WH, Escobar C, Buijs RM, Hu K. Interactive Effects of Dorsomedial Hypothalamic Nucleus and Time-Restricted Feeding on Fractal Motor Activity Regulation. Front Physiol 2016; 7:174. [PMID: 27242548 PMCID: PMC4870237 DOI: 10.3389/fphys.2016.00174] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 05/02/2016] [Indexed: 01/09/2023] Open
Abstract
One evolutionary adaptation in motor activity control of animals is the anticipation of food that drives foraging under natural conditions and is mimicked in laboratory with daily scheduled food availability. Food anticipation is characterized by increased activity a few hours before the feeding period. Here we report that 2-h food availability during the normal inactive phase of rats not only increases activity levels before the feeding period but also alters the temporal organization of motor activity fluctuations over a wide range of time scales from minutes up to 24 h. We demonstrate this multiscale alteration by assessing fractal patterns in motor activity fluctuations—similar fluctuation structure at different time scales—that are robust in intact animals with ad libitum food access but are disrupted under food restriction. In addition, we show that fractal activity patterns in rats with ad libitum food access are also perturbed by lesion of the dorsomedial hypothalamic (DMH)—a neural node that is involved in food anticipatory behavior. Instead of further disrupting fractal regulation, food restriction restores the disrupted fractal patterns in these animals after the DMH lesion despite the persistence of the 24-h rhythms. This compensatory effect of food restriction is more clearly pronounced in the same animals after the additional lesion of the suprachiasmatic nucleus (SCN)—the central master clock in the circadian system that generates and orchestrates circadian rhythms in behavior and physiological functions in synchrony with day-night cycles. Moreover, all observed influences of food restriction persist even when data during the food anticipatory and feeding period are excluded. These results indicate that food restriction impacts dynamics of motor activity at different time scales across the entire circadian/daily cycle, which is likely caused by the competition between the food-induced time cue and the light-entrained circadian rhythm of the SCN. The differential impacts of food restriction on fractal activity control in intact and DMH-lesioned animals suggest that the DMH plays a crucial role in integrating these different time cues to the circadian network for multiscale regulation of motor activity.
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Affiliation(s)
- Men-Tzung Lo
- Medical Biodynamics Program, Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, Harvard Medical SchoolBoston, MA, USA; Institute of Translational and Interdisciplinary Medicine and Department of Biomedical Sciences and Engineering, National Central UniversityTaoyuan, Taiwan
| | - Wei-Yin Chiang
- Medical Biodynamics Program, Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, Harvard Medical School Boston, MA, USA
| | - Wan-Hsin Hsieh
- Medical Biodynamics Program, Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, Harvard Medical School Boston, MA, USA
| | - Carolina Escobar
- Departamento de Anatomía, Facultad de Medicina, Edificio "B" 4° Piso, Universidad Nacional Autónoma de México México, Mexico
| | - Ruud M Buijs
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México México, Mexico
| | - Kun Hu
- Medical Biodynamics Program, Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, Harvard Medical School Boston, MA, USA
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Huang RJ, Lai CH, Lee SD, Wang WC, Tseng LH, Chen YP, Chang SW, Chung AH, Ting H. Scaling exponent values as an ordinary function of the ratio of very low frequency to high frequency powers in heart rate variability over various sleep stages. Sleep Breath 2016; 20:975-85. [DOI: 10.1007/s11325-016-1320-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2015] [Revised: 01/27/2016] [Accepted: 02/08/2016] [Indexed: 01/17/2023]
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15
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Otsuka K, Cornelissen G, Kubo Y, Hayashi M, Yamamoto N, Shibata K, Aiba T, Furukawa S, Ohshima H, Mukai C. Intrinsic cardiovascular autonomic regulatory system of astronauts exposed long-term to microgravity in space: observational study. NPJ Microgravity 2015; 1:15018. [PMID: 28725718 PMCID: PMC5516430 DOI: 10.1038/npjmgrav.2015.18] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Revised: 06/28/2015] [Accepted: 10/12/2015] [Indexed: 11/10/2022] Open
Abstract
The fractal scaling of the long-term heart rate variability (HRV) reflects the 'intrinsic' autonomic regulatory system. Herein, we examine how microgravity on the ISS affected the power-law scaling β (beta) of astronauts during a long-duration (about 6 months) spaceflight. Ambulatory electrocardiographic (ECG) monitoring was performed on seven healthy astronauts (5 men, 52.0±4.2 years of age) five times: before launch, 24±5 (F01) and 73±5 (F02) days after launch, 15±5 days before return (F03), and after return to Earth. The power-law scaling β was calculated as the slope of the regression line of the power density of the MEM spectrum versus frequency plotted on a log10-log10 scale in the range of 0.0001-0.01 Hz (corresponding to periods of 2.8 h to 1.6 min). β was less negative in space (-0.949±0.061) than on Earth (-1.163±0.075; P<0.025). The difference was more pronounced during the awake than during the rest/sleep span. The circadian amplitude and acrophase (phase of maximum) of β did not differ in space as compared with Earth. An effect of microgravity was detected within 1 month (F01) in space and continued throughout the spaceflight. The intrinsic autonomic regulatory system that protects life under serious environmental conditions on Earth is altered in the microgravity environment, with no change over the 6-month spaceflight. It is thus important to find a way to improve conditions in space and/or in terms of human physiology, not to compromise the intrinsic autonomic regulatory system now that plans are being made to inhabit another planet in the near future.
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Affiliation(s)
- Kuniaki Otsuka
- Department of Chronomics and Gerontology, Tokyo Women's Medical University, Tokyo, Japan.,Halberg Chronobiology Center, Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Germaine Cornelissen
- Halberg Chronobiology Center, Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Yutaka Kubo
- Department of Medicine, Tokyo Women's Medical University, Medical Center East, Tokyo, Japan
| | - Mitsutoshi Hayashi
- Department of Medicine, Tokyo Women's Medical University, Medical Center East, Tokyo, Japan
| | - Naomune Yamamoto
- Department of Medicine, Tokyo Women's Medical University, Medical Center East, Tokyo, Japan
| | - Koichi Shibata
- Department of Medicine, Tokyo Women's Medical University, Medical Center East, Tokyo, Japan
| | - Tatsuya Aiba
- Space Biomedical Research Group, Japan Aerospace Exploration Agency, Tokyo, Japan
| | - Satoshi Furukawa
- Space Biomedical Research Group, Japan Aerospace Exploration Agency, Tokyo, Japan
| | - Hiroshi Ohshima
- Space Biomedical Research Group, Japan Aerospace Exploration Agency, Tokyo, Japan
| | - Chiaki Mukai
- Space Biomedical Research Group, Japan Aerospace Exploration Agency, Tokyo, Japan
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16
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Kobuchi S, Ito Y, Nakano Y, Sakaeda T. Population pharmacokinetic modelling and simulation of 5-fluorouracil incorporating a circadian rhythm in rats. Xenobiotica 2015; 46:597-604. [DOI: 10.3109/00498254.2015.1100767] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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17
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Lack of exercise leads to significant and reversible loss of scale invariance in both aged and young mice. Proc Natl Acad Sci U S A 2015; 112:2320-4. [PMID: 25675516 DOI: 10.1073/pnas.1424706112] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In healthy humans and other animals, behavioral activity exhibits scale invariance over multiple timescales from minutes to 24 h, whereas in aging or diseased conditions, scale invariance is usually reduced significantly. Accordingly, scale invariance can be a potential marker for health. Given compelling indications that exercise is beneficial for mental and physical health, we tested to what extent a lack of exercise affects scale invariance in young and aged animals. We studied six or more mice in each of four age groups (0.5, 1, 1.5, and 2 y) and observed an age-related deterioration of scale invariance in activity fluctuations. We found that limiting the amount of exercise, by removing the running wheels, leads to loss of scale-invariant properties in all age groups. Remarkably, in both young and old animals a lack of exercise reduced the scale invariance in activity fluctuations to the same level. We next showed that scale invariance can be restored by returning the running wheels. Exercise during the active period also improved scale invariance during the resting period, suggesting that activity during the active phase may also be beneficial for the resting phase. Finally, our data showed that exercise had a stronger influence on scale invariance than the effect of age. The data suggest that exercise is beneficial as revealed by scale-invariant parameters and that, even in young animals, a lack of exercise leads to strong deterioration in these parameters.
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18
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Yang Y, Jiang Z, Cheng S, Wang Y, Liu Y, Xiao J, Guo H, Li S, Hou W, Wang Z. Nicotinamide adenine dinucleotide: a possible circadian zeitgeber functioning in nontranscription oscillation. BIOL RHYTHM RES 2013. [DOI: 10.1080/09291016.2013.842378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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19
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Yaniv Y, Lyashkov AE, Lakatta EG. The fractal-like complexity of heart rate variability beyond neurotransmitters and autonomic receptors: signaling intrinsic to sinoatrial node pacemaker cells. ACTA ACUST UNITED AC 2013; 2. [PMID: 26709383 DOI: 10.4172/2329-6607.1000111] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The heart rate and rhythm are controlled by complex chaotic neural, chemical and hormonal networks which are not strictly regular, but exhibit fluctuations across multiple time scales. A careful assessment of the heart rate variability (HRV) offers clues to this complexity. A reduction in HRV, specifically in advanced age, is associated with increase in morbidity and mortality. Mechanisms that induce this decrease, however, have not been fully elucidated. The classical literature characterizes changes in HRV as a result of changes in the balance of competing influences of the sympathetic and parasympathetic autonomic impulses delivered to the heart. It has now become clear, however, that the heart rate and HRV are also determined by intrinsic properties of the pacemaker cells that comprise sinoatrial node, and that these properties respond to autonomic receptor stimulation in a non-linear mode. That HRV is determined by both the intrinsic properties of pacemaker cells in the sinoatrial node and the competing influences of the two branches of the autonomic neural input to the cells requires an expansion of our perspective about mechanisms that govern HRV in the normal heart, and how HRV changes with aging in health and in heart diseases.
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Affiliation(s)
- Yael Yaniv
- Laboratory of Cardiovascular Science, Biomedical Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, Maryland, USA
| | - Alexey E Lyashkov
- Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, 733 North Broadway, Baltimore, Maryland, USA
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, Biomedical Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, Maryland, USA
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20
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Pittman-Polletta BR, Scheer FAJL, Butler MP, Shea SA, Hu K. The role of the circadian system in fractal neurophysiological control. Biol Rev Camb Philos Soc 2013; 88:873-94. [PMID: 23573942 DOI: 10.1111/brv.12032] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 02/20/2013] [Accepted: 02/21/2013] [Indexed: 01/31/2023]
Abstract
Many neurophysiological variables such as heart rate, motor activity, and neural activity are known to exhibit intrinsic fractal fluctuations - similar temporal fluctuation patterns at different time scales. These fractal patterns contain information about health, as many pathological conditions are accompanied by their alteration or absence. In physical systems, such fluctuations are characteristic of critical states on the border between randomness and order, frequently arising from nonlinear feedback interactions between mechanisms operating on multiple scales. Thus, the existence of fractal fluctuations in physiology challenges traditional conceptions of health and disease, suggesting that high levels of integrity and adaptability are marked by complex variability, not constancy, and are properties of a neurophysiological network, not individual components. Despite the subject's theoretical and clinical interest, the neurophysiological mechanisms underlying fractal regulation remain largely unknown. The recent discovery that the circadian pacemaker (suprachiasmatic nucleus) plays a crucial role in generating fractal patterns in motor activity and heart rate sheds an entirely new light on both fractal control networks and the function of this master circadian clock, and builds a bridge between the fields of circadian biology and fractal physiology. In this review, we sketch the emerging picture of the developing interdisciplinary field of fractal neurophysiology by examining the circadian system's role in fractal regulation.
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Affiliation(s)
- Benjamin R Pittman-Polletta
- Medical Biodynamics Program, Division of Sleep Medicine, Brigham and Women's Hospital, Boston, MA, 02115, U.S.A.; Medical Chronobiology Program, Division of Sleep Medicine, Brigham and Women's Hospital, Boston, MA, 02115, U.S.A.; Division of Sleep Medicine, Harvard Medical School, Boston, MA, 02115, U.S.A
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21
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Cheng S, Jiang Z, Zou Y, Chen C, Wang Y, Liu Y, Xiao J, Guo H, Wang Z. Downregulation of Clock in circulatory system leads to an enhancement of fibrinolysis in mice. Exp Biol Med (Maywood) 2011; 236:1078-84. [PMID: 21750017 DOI: 10.1258/ebm.2011.010322] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
As a main component of circadian genes, clock plays not only an important role in circadian rhythm but also in the regulation of many physiological systems. The dysfunction of clock genes is associated with the development of various disorders. Many studies have investigated the association between clock genes and blood coagulation and the fibrinolytic system. The present study was designed to investigate the effect of downregulation of circulatory Clock on blood coagulation and fibrinolysis at the initial stage of active phase in male mice. Downregulation of the expression of the Clock gene by siRNA and, subsequently, its effect on the thrombotic potential and the expression of relative coagulative and/or fibrinolytic factors were investigated. It was found that the Clock interfered mice were less liable to thrombosis and showed prolonged prothrombin time (PT) and activated partial thromboplastin time (APTT) at Zeitgeber time (ZT) 15. Meanwhile, these mice also showed an increase in factor VII (FVII) and a decrease in thrombomodulin (TM) and plasminogen activator inhibitor 1 (PAI-1) at ZT 15 at both transcriptional and translational levels. PT, APTT and mRNA expressions of fvii, tm and pai-1 were analyzed with the least-squares fit of a 24-h cosine function by single cosinor method; no circadian rhythm was determined in PT and APTT, and a higher amplitude of fvii in the Clock RNAi group was found with a circadian phase shift, while lower amplitudes of tm and pai-1 were found in the Clock RNAi group with nearly no phase shift. All these results suggest that downregulation of the Clock gene in circulatory system has an effect on factors involved in both blood coagulation and fibrinolysis resulting in an enhancement in mice. This may be considered as an indication that Clock regulates thrombotic homeostasis through the fibrinolytic system.
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Affiliation(s)
- Shuting Cheng
- Key Laboratory of Chronobiology, Ministry of Health (Sichuan University), Chengdu, Sichuan, PR China
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22
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Abstract
The presence of day-night variations in cardiovascular and metabolic functioning is well known. However, only recently it has been shown that cardiovascular and metabolic processes are not only affected by the behavioral sleep/wake cycle but are partly under direct control of the master circadian pacemaker located in the suprachiasmatic nucleus (SCN). Heart rate, cardiac autonomic activity, glucose metabolism and leptin-involved in appetite control-all show circadian variation (i.e., under constant behavioral and environmental conditions). This knowledge of behavioral vs. circadian modulation of cardiometabolic function is of clinical relevance given the morning peak in adverse cardiovascular incidents observed in epidemiological studies and given the increased risk for the development of diabetes, obesity, and cardiovascular disease in shift workers. We will review the evidence for circadian control of cardiometabolic functioning, as well its sensitivity to light and melatonin, and discuss potential implication for therapy.
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Affiliation(s)
- Melanie Rüger
- Division of Sleep Medicine, Harvard Medical School, Brigham and Women's Hospital, 221 Longwood Avenue, Boston, MA 02115, USA.
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23
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Spary EJ, Maqbool A, Batten TFC. Oestrogen receptors in the central nervous system and evidence for their role in the control of cardiovascular function. J Chem Neuroanat 2009; 38:185-96. [PMID: 19505570 DOI: 10.1016/j.jchemneu.2009.05.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Revised: 05/05/2009] [Accepted: 05/27/2009] [Indexed: 02/07/2023]
Abstract
Oestrogen is considered beneficial to cardiovascular health through protective effects not only on the heart and vasculature, but also on the autonomic nervous system via actions on oestrogen receptors. A plethora of evidence supports a role for the hormone within the central nervous system in modulating the pathways regulating cardiovascular function. A complex interaction of several brainstem, spinal and forebrain nuclei is required to receive, integrate and co-ordinate inputs that contribute appropriate autonomic reflex responses to changes in blood pressure and other cardiovascular parameters. Central effects of oestrogen and oestrogen receptors have already been demonstrated in many of these areas. In addition to the classical nuclear oestrogen receptors (ERalpha and ERbeta) a recently discovered G-protein coupled receptor, GPR30, has been shown to be a novel mediator of oestrogenic action. Many anatomical and molecular studies have described a considerable overlap in the regional expression of these receptors; however, the receptors do exhibit specific characteristics and subtype specific expression is found in many autonomic brain areas, for example ERbeta appears to predominate in the hypothalamic paraventricular nucleus, whilst ERalpha is important in the nucleus of the solitary tract. This review provides an overview of the available information on the localisation of oestrogen receptor subtypes and their multitude of possible modulatory actions in different groups of neurochemically and functionally defined neurones in autonomic-related areas of the brain.
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Affiliation(s)
- Emma J Spary
- Division of Cardiovascular and Neuronal Remodelling, Worsley Building, LIGHT Institute, University of Leeds, Leeds LS2 9JT, UK.
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24
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Zuloaga DG, McGivern RF, Handa RJ. Organizational influence of the postnatal testosterone surge on the circadian rhythm of core body temperature of adult male rats. Brain Res 2009; 1268:68-75. [PMID: 19272357 DOI: 10.1016/j.brainres.2009.02.048] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2008] [Revised: 02/11/2009] [Accepted: 02/14/2009] [Indexed: 10/21/2022]
Abstract
The suprachiasmatic nucleus (SCN) of the hypothalamus coordinates physiological and behavioral circadian rhythms such as activity, body temperature, and hormone secretion. Circadian rhythms coordinated by the SCN often show sex differences arising from both organizational and activational effects of gonadal hormones. In males, little is known about the organizational role of testosterone on the circadian regulation of core body temperature (CBT) in adulthood. To explore this, we castrated or sham-operated male rats on the day of birth, and at 4 months of age, implanted them with transmitters that measured CBT rhythms under a 12:12 light/dark cycle. This study revealed a significantly earlier rise in CBT during the light phase in neonatally castrated males. Subsequently, we found that treating neonatally castrated males with testosterone propionate (TP) in adulthood did not reverse the effect of neonatal castration, thus indicating an organizational role for testosterone. In contrast, a single injection of TP at the time of neonatal surgery, to mimic the postnatal surge of testosterone, coupled with TP treatment in adulthood, normalized the circadian rise in CBT. In a final study we examined CBT circadian rhythms in intact adult male and female rats and detected no differences in the rise of CBT during the light phase, although there was a greater overall elevation in female CBT. Together, results of these studies reveal an early organizational role of testosterone in males on the timing of the circadian rise of CBT, a difference that does not appear to reflect "defeminization".
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Affiliation(s)
- Damian G Zuloaga
- Department of Psychology, San Diego State University, San Diego, CA, USA; Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, AZ 85004, USA.
| | - Robert F McGivern
- Department of Psychology, San Diego State University, San Diego, CA, USA
| | - Robert J Handa
- Department of Biomedical Sciences, Colorado State Univ., Fort Collins, CO 80523, USA; Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, AZ 85004, USA
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25
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Hu K, Scheer FAJL, Buijs RM, Shea SA. The endogenous circadian pacemaker imparts a scale-invariant pattern of heart rate fluctuations across time scales spanning minutes to 24 hours. J Biol Rhythms 2008; 23:265-73. [PMID: 18487418 DOI: 10.1177/0748730408316166] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Heartbeat fluctuations in mammals display a robust temporal structure characterized by scale-invariant/fractal patterns. These scale-invariant patterns likely confer physiological advantage because they change with cardiovascular disease and these changes are associated with reduced survival. Models of physical systems imply that to produce scale-invariant patterns, factors influencing the system at different time scales must be coupled via a network of feedback interactions. A similar cardiac control network is hypothesized to be responsible for the scale-invariant pattern in heartbeat dynamics, although the essential network components have not been determined. Here is shown that scale-invariant cardiac control occurs across time scales from minutes to approximately 24 h, and that lesioning the mammalian circadian pacemaker (suprachiasmatic nucleus; SCN) completely abolishes the scale-invariant pattern at time scales>or approximately 4 h. At time scales<or approximately 4 h, the scale invariance persisted following SCN lesion but with a different pattern. These results indicate previously unrecognized multiscale influences of the SCN on heart rate fluctuations that cannot be explained by a simple pacemaker of 24-h rhythmicity. The conclusion is that the SCN serves as a major node in the cardiac control network and imparts scale-invariant cardiac control across a wide range of time scales with strongest effects between approximately 4 and 24 h. These results demonstrate that experimental manipulations (e.g., SCN lesion) can be used to begin to model and understand the origin of scale-invariant behavior in a neurophysiological system.
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Affiliation(s)
- Kun Hu
- Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02215, USA.
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