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1

Circadian Rhythms  

MedlinePLUS

... are found in most living things, including animals, plants and many tiny microbes. The study of circadian rhythms is called chronobiology. Are circadian rhythms the same thing as biological clocks? No, but they are related. Our biological clocks ...

2

A model for generating circadian rhythm by coupling ultradian oscillators  

PubMed Central

Background Organisms ranging from humans to cyanobacteria undergo circadian rhythm, that is, variations in behavior that cycle over a period about 24 hours in length. A fundamental property of circadian rhythm is that it is free-running, and continues with a period close to 24 hours in the absence of light cycles or other external cues. Regulatory networks involving feedback inhibition and feedforward stimulation of mRNA transcription and translation are thought to be critical for many circadian mechanisms, and genes coding for essential components of circadian rhythm have been identified in several organisms. However, it is not clear how such components are organized to generate a circadian oscillation. Results We propose a model in which two independent transcriptional-translational oscillators with periods much shorter than 24 hours are coupled to drive a forced oscillator that has a circadian period, using mechanisms and parameters of conventional molecular biology. Furthermore, the resulting circadian oscillator can be entrained by an external light-dark cycle through known mechanisms. We rationalize the mathematical basis for the observed behavior of the model, and show that the behavior is not dependent on the details of the component ultradian oscillators but occurs even if quite generalized basic oscillators are used. Conclusion We conclude that coupled, independent, transcriptional-translational oscillators with relatively short periods can be the basis for circadian oscillators. The resulting circadian oscillator can be entrained by 24-hour light-dark cycles, and the model suggests a mechanism for its evolution. PMID:16504091

Paetkau, Verner; Edwards, Roderick; Illner, Reinhard

2006-01-01

3

Hierarchically coupled ultradian oscillators generating robust circadian rhythms  

Microsoft Academic Search

Ensembles of mutually coupled ultradian cellular oscillators have been proposed by a number of authors to explain the generation of circadian rhythms in mammals. Most mathematical models using many coupled oscillators predict that the output period should vary as the square root of the number of participating units, thus being inconsistent with the well-established experimental result that ablation of substantial

Rafael A. Barrio; Limei Zhang; Philip K. Maini

1997-01-01

4

CIRCADIAN RHYTHMS Circadian Photoreception  

NSDL National Science Digital Library

The circadian rhythms of physiology and behavior are driven by autonomous cellular clocks. To be useful, these clocks must be synchronized to the day-night cycles of the real world. This article provides a review of research on circadian photoreceptors in mammals.

Michael Menaker (University of Virginia;Department of Biology)

2003-01-10

5

Biological Clocks & Circadian Rhythms  

ERIC Educational Resources Information Center

The study of biological clocks and circadian rhythms is an excellent way to address the inquiry strand in the National Science Education Standards (NSES) (NRC 1996). Students can study these everyday phenomena by designing experiments, gathering and analyzing data, and generating new experiments. As students explore biological clocks and circadian

Robertson, Laura; Jones, M. Gail

2009-01-01

6

Circadian Rhythm Sleep Disorders  

PubMed Central

There have been remarkable advances in our understanding of the molecular, cellular and physiological mechanisms underlying the regulation of circadian rhythms, as well as the impact of circadian dysfunction on health and disease. This information has transformed our understanding of the effect of circadian rhythm sleep disorders (CRSD) on health, performance and safety. CRSDs are caused by alterations of the central circadian time-keeping system, or a misalignment of the endogenous circadian rhythm and the external environment. In this section, we provide a review of circadian biology and discuss the pathophysiology, clinical features, diagnosis, and treatment of the most commonly encountered CRSDs in clinical practice. PMID:23099133

Zhu, Lirong; Zee, Phyllis C.

2012-01-01

7

Stochastic simulations on a model of circadian rhythm generation.  

PubMed

Biological phenomena are often modeled by differential equations, where states of a model system are described by continuous real values. When we consider concentrations of molecules as dynamical variables for a set of biochemical reactions, we implicitly assume that numbers of the molecules are large enough so that their changes can be regarded as continuous and they are described deterministically. However, for a system with small numbers of molecules, changes in their numbers are apparently discrete and molecular noises become significant. In such cases, models with deterministic differential equations may be inappropriate, and the reactions must be described by stochastic equations. In this study, we focus a clock gene expression for a circadian rhythm generation, which is known as a system involving small numbers of molecules. Thus it is appropriate for the system to be modeled by stochastic equations and analyzed by methodologies of stochastic simulations. The interlocked feedback model proposed by Ueda et al. as a set of deterministic ordinary differential equations provides a basis of our analyses. We apply two stochastic simulation methods, namely Gillespie's direct method and the stochastic differential equation method also by Gillespie, to the interlocked feedback model. To this end, we first reformulated the original differential equations back to elementary chemical reactions. With those reactions, we simulate and analyze the dynamics of the model using two methods in order to compare them with the dynamics obtained from the original deterministic model and to characterize dynamics how they depend on the simulation methodologies. PMID:18585851

Miura, Shigehiro; Shimokawa, Tetsuya; Nomura, Taishin

2008-01-01

8

Biological Clocks and Circadian Rhythms  

NSDL National Science Digital Library

The study of biological clocks and circadian rhythms is an excellent way to address the inquiry strand in the National Science Education Standards (NSES) (NRC 1996). Students can study these everyday phenomena by designing experiments, gathering and analyzing data, and generating new experiments. As students explore biological clocks and circadian rhythms, they are provided with opportunities to connect learning to experiences and observations from their own lives. This article describes how to reset the biological clock of a shamrock plant while shedding light on its circadian rhythms.

Laura Robertson

2009-02-01

9

Circadian Rhythm Abnormalities  

PubMed Central

Purpose: This article reviews the recent advances in understanding of the fundamental properties of circadian rhythms and discusses the clinical features, diagnosis, and treatment of circadian rhythm sleep disorders (CRSDs). Recent Findings: Recent evidence strongly points to the ubiquitous influence of circadian timing in nearly all physiologic functions. Thus, in addition to the prominent sleep and wake disturbances, circadian rhythm disorders are associated with cognitive impairment, mood disturbances, and increased risk of cardiometabolic disorders. The recent availability of biomarkers of circadian timing in clinical practice has improved our ability to identify and treat these CRSDs. Summary: Circadian rhythms are endogenous rhythms with a periodicity of approximately 24 hours. These rhythms are synchronized to the physical environment by social and work schedules by various photic and nonphotic stimuli. CRSDs result from a misalignment between the timing of the circadian rhythm and the external environment (eg, jet lag and shift work) or a dysfunction of the circadian clock or its afferent and efferent pathways (eg, delayed sleep-phase, advanced sleep-phase, non–24-hour, and irregular sleep-wake rhythm disorders). The most common symptoms of these disorders are difficulties with sleep onset and/or sleep maintenance and excessive sleepiness that are associated with impaired social and occupational functioning. Effective treatment for most of the CRSDs requires a multimodal approach to accelerate circadian realignment with timed exposure to light, avoidance of bright light at inappropriate times, and adherence to scheduled sleep and wake times. In addition, pharmacologic agents are recommended for some of the CRSDs. For delayed sleep-phase, non–24-hour, and shift work disorders, timed low-dose melatonin can help advance or entrain circadian rhythms; and for shift work disorder, wake-enhancing agents such as caffeine, modafinil, and armodafinil are options for the management of excessive sleepiness. PMID:23385698

Zee, Phyllis C.; Attarian, Hrayr; Videnovic, Aleksandar

2013-01-01

10

Measuring stem cell circadian rhythm.  

PubMed

Circadian rhythms are biological rhythms that occur within a 24-h time cycle. Sleep is a prime example of a circadian rhythm and with it melatonin production. Stem cell systems also demonstrate circadian rhythms. This is particularly the case for the proliferating cells within the system. In fact, all proliferating cell populations exhibit their own circadian rhythm, which has important implications for disease and the treatment of disease. Stem cell chronobiology is particularly important because the treatment of cancer can be significantly affected by the time of day a drug is administered. This protocol provides a basis for measuring hematopoietic stem cell circadian rhythm for future stem cell chronotherapeutic applications. PMID:25388388

Hrushesky, William; Rich, Ivan N

2015-01-01

11

[Circadian rhythm sleep disorder].  

PubMed

Primary pathophysiology of circadian rhythm sleep disorders(CRSDs) is a misalignment between the endogenous circadian rhythm phase and the desired or socially required sleep-wake schedule, or dysfunction of the circadian pacemaker and its afferent/efferent pathways. CRSDs consist of delayed sleep phase type, advanced sleep phase type, free-running type, irregular sleep-wake type, shift work type and jet lag type. Chronotherapy using strong zeitgebers (time cues), such as bright light and melatonin/ melatonin type 2 receptor agonist, is effective when administered with proper timing. Bright light is the strongest entraining agent of circadian rhythms. Bright light therapy (appropriately-timed exposure to bright light) for CRSDs is an effective treatment option, and can shift the sleep-wake cycle to earlier or later times, in order to correct for misalignment between the circadian system and the desired sleep-wake schedule. Timed administration of melatonin, either alone or in combination with light therapy has also been shown to be useful in the treatment of CRSDs. PMID:24437262

Mishima, Kazuo

2013-12-01

12

Melatonin for Circadian Rhythm Disturbances in Dementia  

E-print Network

Melatonin for Circadian Rhythm Disturbances in Dementia Available from: http. Describe the pathophysiology of circadian rhythm disturbances in dementia 2. Evaluate current treatment options for circadian rhythm disturbances in dementia 3. Review available literature on the use

Pillow, Jonathan

13

Circadian rhythms regulate amelogenesis.  

PubMed

Ameloblasts, the cells responsible for making enamel, modify their morphological features in response to specialized functions necessary for synchronized ameloblast differentiation and enamel formation. Secretory and maturation ameloblasts are characterized by the expression of stage-specific genes which follows strictly controlled repetitive patterns. Circadian rhythms are recognized as key regulators of the development and diseases of many tissues including bone. Our aim was to gain novel insights on the role of clock genes in enamel formation and to explore the potential links between circadian rhythms and amelogenesis. Our data shows definitive evidence that the main clock genes (Bmal1, Clock, Per1 and Per2) oscillate in ameloblasts at regular circadian (24 h) intervals both at RNA and protein levels. This study also reveals that the two markers of ameloblast differentiation i.e. amelogenin (Amelx; a marker of secretory stage ameloblasts) and kallikrein-related peptidase 4 (Klk4, a marker of maturation stage ameloblasts) are downstream targets of clock genes. Both, Amelx and Klk4 show 24h oscillatory expression patterns and their expression levels are up-regulated after Bmal1 over-expression in HAT-7 ameloblast cells. Taken together, these data suggest that both the secretory and the maturation stages of amelogenesis might be under circadian control. Changes in clock gene expression patterns might result in significant alterations of enamel apposition and mineralization. PMID:23486183

Zheng, Li; Seon, Yoon Ji; Mourão, Marcio A; Schnell, Santiago; Kim, Doohak; Harada, Hidemitsu; Papagerakis, Silvana; Papagerakis, Petros

2013-07-01

14

[Depression and circadian rhythm].  

PubMed

Adverse changes in circadian rhythms are an integral part of the clinical features of endogenous depression, and particularly of seasonal depression. Alongside twenty-four variations in the major symptoms, these forms of depression can be characterised psychometrically, physiologically and biologically. The most classical adverse changes are amplitude modifications, fluctuations and periodicity of the hormonal secretory rhythms. Pathophysiological and psychopathological models have been proposed to combat these abnormalities. The leading models include free course, phase advance (or instability) and hypnic models, or those based on disturbances of the internal clock. The main psychopathological models are those of endokinesis and psychosocial desynchronisation. The therapeutic applications of the pathophysiological models use manipulation of the wake-sleep cycle, phototherapy and melatonin and its derivatives : those of the psychopathological models used time-space management and development of resynchronisation capacities. The question determining whether these adverse changes are a cause or effect of depressive behaviour is unresolved. PMID:19268174

Azorin, J M; Kaladjian, A

2009-01-01

15

Circadian rhythms in the green sunfish retina  

PubMed Central

We investigated the occurrence of circadian rhythms in retinomotor movements and retinal sensitivity in the green sunfish, Lepomis cyanellus. When green sunfish were kept in constant darkness, cone photoreceptors exhibited circadian retinomotor movements; rod photoreceptors and retinal pigment epithelium (RPE) pigment granules did not. Cones elongated during subjective night and contracted during subjective day. These results corroborate those of Burnside and Ackland (1984. Investigative Ophthalmology and Visual Science. 25:539-545). Electroretinograms (ERGs) recorded in constant darkness in response to dim flashes (lambda = 640 nm) exhibited a greater amplitude during subjective night than during subjective day. The nighttime increase in the ERG amplitude corresponded to a 3-10-fold increase in retinal sensitivity. The rhythmic changes in the ERG amplitude continued in constant darkness with a period of approximately 24 h, which indicates that the rhythm is generated by a circadian oscillator. The spectral sensitivity of the ERG recorded in constant darkness suggests that cones contribute to retinal responses during both day and night. Thus, the elongation of cone myoids during the night does not abolish the response of the cones. To examine the role of retinal efferents in generating retinal circadian rhythms, we cut the optic nerve. This procedure did not abolish the rhythms of retinomotor movement or of the ERG amplitude, but it did reduce the magnitude of the nighttime phases of both rhythms. Our results suggest that more than one endogenous oscillator regulates the retinal circadian rhythms in green sunfish. Circadian signals controlling the rhythms may be either generated within the eye or transferred to the eye via a humoral pathway. PMID:3598559

1987-01-01

16

Circadian rhythms in the green sunfish retina.  

PubMed

We investigated the occurrence of circadian rhythms in retinomotor movements and retinal sensitivity in the green sunfish, Lepomis cyanellus. When green sunfish were kept in constant darkness, cone photoreceptors exhibited circadian retinomotor movements; rod photoreceptors and retinal pigment epithelium (RPE) pigment granules did not. Cones elongated during subjective night and contracted during subjective day. These results corroborate those of Burnside and Ackland (1984. Investigative Ophthalmology and Visual Science. 25:539-545). Electroretinograms (ERGs) recorded in constant darkness in response to dim flashes (lambda = 640 nm) exhibited a greater amplitude during subjective night than during subjective day. The nighttime increase in the ERG amplitude corresponded to a 3-10-fold increase in retinal sensitivity. The rhythmic changes in the ERG amplitude continued in constant darkness with a period of approximately 24 h, which indicates that the rhythm is generated by a circadian oscillator. The spectral sensitivity of the ERG recorded in constant darkness suggests that cones contribute to retinal responses during both day and night. Thus, the elongation of cone myoids during the night does not abolish the response of the cones. To examine the role of retinal efferents in generating retinal circadian rhythms, we cut the optic nerve. This procedure did not abolish the rhythms of retinomotor movement or of the ERG amplitude, but it did reduce the magnitude of the nighttime phases of both rhythms. Our results suggest that more than one endogenous oscillator regulates the retinal circadian rhythms in green sunfish. Circadian signals controlling the rhythms may be either generated within the eye or transferred to the eye via a humoral pathway. PMID:3598559

Dearry, A; Barlow, R B

1987-05-01

17

Light, circadian and circannual rhythms  

Microsoft Academic Search

Organisms use circadian and circannual rhythms in cells or cell complexes for time measurements, thus the term biological clocks. Properties and models of biological clocks are discussed. In mammals, the biological clock system perceives light signals via the retina. Signals are then led to the suprachiasmatic nucleus (SCN) of the brain, functioning as the central clock region. Via pathways -

Anders Johnsson

18

Circadian rhythm sleep disorders (CRSD)  

Microsoft Academic Search

Circadian Rhythm Sleep Disorders (CRSD) are a group of sleep disorders characterized by a malsynchronization between a person's biological clock and the environmental 24-h schedule. These disorders can lead to harmful psychological and functional difficulties and are often misdiagnosed and incorrectly treated due to the fact that doctors are unaware of their existence. In the following review we describe the

Yaron Dagan

2002-01-01

19

[Circadian rhythm and mood disorder].  

PubMed

Mood disorders show a common feature of distorted cycling of biological systems, manifesting, for example, as diurnal mood variation in depression, phasic time course in bipolar disorder, and seasonal mood swing in seasonal affective disorder. Accordingly, circadian dysfunction has been supposed to play an etiological role in mood disorders. Increasing evidence indicates that circadian misalignment between neuroendocrinological rhythm and the timing of sleep correlates with the severity of symptoms. In addition, several genetic studies have suggested that certain clock gene variants play a role in vulnerability to these disorders, and especially bipolar disorders. However, the role of circadian phenotypes and circadian genes in mood spectrum disorders remains unclear, although currently seem to have a pathoplastic rather than a pathogenetic effect. PMID:24437274

Konno, Michiko

2013-12-01

20

Circadian rhythms, melatonin and depression.  

PubMed

The master biological clock situated in the suprachiasmatic nuclei of the anterior hypothalamus plays a vital role in orchestrating the circadian rhythms of multiple biological processes. Increasing evidence points to a role of the biological clock in the development of depression. In seasonal depression and in bipolar disorders it seems likely that the circadian system plays a vital role in the genesis of the disorder. For major unipolar depressive disorder (MDD) available data suggest a primary involvement of the circadian system but further and larger studies are necessary to conclude. Melatonin and melatonin agonists have chronobiotic effects, which mean that they can readjust the circadian system. Seasonal affective disorders and mood disturbances caused by circadian malfunction are theoretically treatable by manipulating the circadian system using chronobiotic drugs, chronotherapy or bright light therapy. In MDD, melatonin alone has no antidepressant action but novel melatoninergic compounds demonstrate antidepressant properties. Of these, the most advanced is the novel melatonin agonist agomelatine, which combines joint MT1 and MT2 agonism with 5-HT(2C) receptor antagonism. Adding a chronobiotic effect to the inhibition of 5-HT(2C) receptors may explain the rapid impact of agomelatine on depression, since studies showed that agomelatine had an early impact on sleep quality and alertness at awakening. Further studies are necessary in order to better characterize the effect of agomelatine and other novel melatoninergic drugs on the circadian system of MDD patients. In summary, antidepressants with intrinsic chronobiotic properties offer a novel approach to treatment of depression. PMID:21476953

Quera Salva, M A; Hartley, S; Barbot, F; Alvarez, J C; Lofaso, F; Guilleminault, C

2011-01-01

21

Circadian Rhythm Control: Neurophysiological Investigations  

NASA Technical Reports Server (NTRS)

The suprachiasmatic nucleus (SCN) was implicated as a primary component in central nervous system mechanisms governing circadian rhythms. Disruption of the normal synchronization of temperature, activity, and other rhythms is detrimental to health. Sleep wake disorders, decreases in vigilance and performance, and certain affective disorders may result from or be exacerbated by such desynchronization. To study the basic neurophysiological mechanisms involved in entrainment of circadian systems by the environment, Parylene-coated, etched microwire electrode bundles were used to record extracellular action potentials from the small somata of the SCN and neighboring hypothalamic nuclei in unanesthetized, behaving animals. Male Wistar rats were anesthetized and chronically prepared with EEG ane EMG electrodes in addition to a moveable microdrive assembly. The majority of cells had firing rates 10 Hz and distinct populations of cells which had either the highest firing rate or lowest firing rate during sleep were seen.

Glotzbach, S. F.

1985-01-01

22

Circadian Rhythm Disruption in Cancer Biology  

PubMed Central

Circadian rhythms show universally a 24-h oscillation pattern in metabolic, physiological and behavioral functions of almost all species. This pattern is due to a fundamental adaptation to the rotation of Earth around its own axis. Molecular mechanisms of generation of circadian rhythms organize a biochemical network in suprachiasmatic nucleus and peripheral tissues, building cell autonomous clock pacemakers. Rhythmicity is observed in transcriptional expression of a wide range of clock-controlled genes that regulate a variety of normal cell functions, such as cell division and proliferation. Desynchrony of this rhythmicity seems to be implicated in several pathologic conditions, including tumorigenesis and progression of cancer. In 2007, the International Agency for Research on Cancer (IARC) categorized “shiftwork that involves circadian disruption [as] probably carcinogenic to humans” (Group 2A in the IARC classification system of carcinogenic potency of an agentagent) (Painting, Firefighting, and Shiftwork; IARC; 2007). This review discusses the potential relation between disruptions of normal circadian rhythms with genetic driving machinery of cancer. Elucidation of the role of clockwork disruption, such as exposure to light at night and sleep disruption, in cancer biology could be important in developing new targeted anticancer therapies, optimizing individualized chronotherapy and modifying lighting environment in workplaces or homes. PMID:22811066

Savvidis, Christos; Koutsilieris, Michael

2012-01-01

23

Circadian Rhythms in Drosophila: A Connections Map  

NSDL National Science Digital Library

Genetic and biochemical experiments over the past decade have allowed the construction of a viable working model for the molecular mechanisms underlying circadian rhythm generation in Drosophila. The basic mechanism consists of two intertwined transcription-translation negative feedback loops. One loop--the "positive loop"--controls the rhythmic expression of a Per-Arnt-Sim (PAS)-domain-containing positive transcription factor, Clock. The second loop--the "negative loop"--controls the transcription of period and timeless, two genes encoding repressor proteins. The loops are intertwined because Period and Timeless directly repress transcription mediated by the Clock:Cycle heterodimer, whereas Clock:Cycle drives transcription of period and timeless, as well as that of vrille, a repressor of Clock expression. Other proteins, including kinases encoded by doubletime, shaggy, Andante, and Timekeeper, also have essential functions in the timekeeping mechanism. Light cycles can synchronize the Drosophila circadian pathway by directly stimulating Cryptochrome-dependent degradation of Timeless. This Pathway Map of the Drosophila circadian mechanism describes the individual known components of the fly circadian clock and their mutual interactions. An accompanying animation schematizes the dynamic interactions of the different components. Science Viewpoint R. N. Van Gelder, E. D. Herzog, W. J. Schwartz, P. H. Taghert, Circadian rhythms: In the loop at last. Science 300, 1534-1535 (2003). [Abstract] [Full Text

Russell N. Van Gelder (Department of Molecular Biology and Pharmacology;Department of Ophthalmology and Visual Sciences REV)

2003-08-05

24

[Relation between dementia and circadian rhythm disturbance].  

PubMed

Dementia and circadian rhythm disturbance are closely linked. First, dementia patient shows circadian rhythm disorders (e.g. insomnia, night wandering, daytime sleep). These symptoms are a burden for caregivers. Circadian rhythm disturbance of dementia relates ADL and cognitive impairment, and diurnal rhythm disorder of blood pressure and body temperature. Some study shows that circadian rhythm disorders in dementia are a disturbance of neural network between suprachiasmatic nucleus and cerebral white matter, and involvement of both frontal lobes, left parietal and occipital cortex, left temporoparietal region. The first-line treatment of circadian rhythm disturbance should be non-drug therapy (e.g. exercise, bright light exposure, reduce caffeine intake, etc.). If physician prescribe drugs, keep the rule of low-dose and short-term and avoid benzodiazepines. Atypical antipsychotic drugs like risperidone and some antidepressants are useful for treatment of insomnia in dementia. But this usage is off-label. So we must well inform to patient and caregiver, and get consent about treatment. Second, some study shows circadian rhythm disorder is a risk factor of dementia. However, we should discuss that circadian rhythm disturbance is "risk factor of dementia" or "prodromal symptom of dementia". If a clinician finds circadian rhythm disorder in elderly people, should be examined cognitive and ADL function, and careful about that patients have dementia or will develop dementia. PMID:24724422

Nakamura, Kei; Meguro, Kenichi

2014-03-01

25

Circadian Rhythms and Cancer Chronotherapeutics  

Microsoft Academic Search

\\u000a The Circadian Timing System (CTS) controls cellular proliferation and drug metabolism over a 24-h period through molecular\\u000a clocks in each cell. These cellular clocks are coordinated by a hypothalamic pacemaker, the suprachiasmatic nuclei, which\\u000a generate or control circadian physiology. The CTS down-regulates malignant growth in experimental models and in cancer patients.\\u000a It also generates large and predictable 24-h changes in

Francis Lévi; Atilla Altinok; Albert Goldbeter

26

Circadian rhythms in myocardial metabolism and function  

Technology Transfer Automated Retrieval System (TEKTRAN)

Circadian rhythms in myocardial function and dysfunction are firmly established in both animal models and humans. For example, the incidence of arrhythmias and sudden cardiac death increases when organisms awaken. Such observations have classically been explained by circadian rhythms in neurohumoral...

27

Circadian rhythms and treatment implications in depression.  

PubMed

In humans almost all physiological and behavioural functions occur on a rhythmic basis. Therefore the possibility that delays, advances or desynchronizations of circadian rhythms may play a role in the pathophysiology of psychiatric disorders is an interesting field of research. In particular mood disorders such as seasonal affective disorder and major depression have been linked to circadian rhythms alterations. Furthermore, the antidepressant efficacy of both pharmacological and non-pharmacological strategies affecting endogenous circadian rhythms, such as new antidepressant medications, light-therapy and sleep deprivation, is consistent with the idea that circadian alterations may represent a core component of depression, at least in a subgroup of depressed patients. This paper briefly describes the molecular and genetic mechanisms regulating the endogenous clock system, and reviews the literature supporting the relationships between depression, antidepressant treatments and changes in circadian rhythms. PMID:20691746

Monteleone, Palmiero; Martiadis, Vassilis; Maj, Mario

2011-08-15

28

Circadian Rhythms and Obesity in Mammals  

PubMed Central

Obesity has become a serious public health problem and a major risk factor for the development of illnesses, such as insulin resistance and hypertension. Attempts to understand the causes of obesity and develop new therapeutic strategies have mostly focused on caloric intake and energy expenditure. Recent studies have shown that the circadian clock controls energy homeostasis by regulating the circadian expression and/or activity of enzymes, hormones, and transport systems involved in metabolism. Moreover, disruption of circadian rhythms leads to obesity and metabolic disorders. Therefore, it is plausible that resetting of the circadian clock can be used as a new approach to attenuate obesity. Feeding regimens, such as restricted feeding (RF), calorie restriction (CR), and intermittent fasting (IF), provide a time cue and reset the circadian clock and lead to better health. In contrast, high-fat (HF) diet leads to disrupted circadian expression of metabolic factors and obesity. This paper focuses on circadian rhythms and their link to obesity. PMID:24527263

Froy, Oren

2012-01-01

29

PPAR? is a potential therapeutic target of drugs to treat circadian rhythm sleep disorders  

Microsoft Academic Search

Recent progress at the molecular level has revealed that nuclear receptors play an important role in the generation of mammalian circadian rhythms. To examine whether peroxisome proliferator-activated receptor alpha (PPAR?) is involved in the regulation of circadian behavioral rhythms in mammals, we evaluated the locomotor activity of mice administered with the hypolipidemic PPAR? ligand, bezafibrate. Circadian locomotor activity was phase-advanced

Hidenori Shirai; Katsutaka Oishi; Takashi Kudo; Shigenobu Shibata; Norio. Ishida

2007-01-01

30

Modelling circadian rhythms of protein KaiA, KaiB and KaiC interactions in cyanobacteria  

E-print Network

Modelling circadian rhythms of protein KaiA, KaiB and KaiC interactions in cyanobacteria SHAO LI 100084, P. R. China Abstract Cyanobacteria are the simplest organisms known that exhibit circadian rhythms. The mechanism of circadian rhythm generation in cyanobacteria is different from eukaryotes. Based

Li, Shao

31

Circadian rhythm dysregulation in bipolar disorder.  

PubMed

When circadian rhythms - the daily oscillations of various physiological and behavioral events that are controlled by a central timekeeping mechanism - become desynchronized with the prevailing light:dark cycle, a maladaptative response can result. Animal data based primarily on genetic manipulations and clinical data from biomarker and gene expression studies support the notion that circadian abnormalities underlie certain psychiatric disorders. In particular, bipolar disorder has an interesting link to rhythm-related disease biology; other mood disturbances, such as major depressive disorder, seasonal affective disorder and the agitation and aggression accompanying severe dementia (sundowning), are also linked to changes in circadian rhythm function. Possibilities for pharmacological intervention derive most readily from the molecular oscillator, the cellular machinery that drives daily rhythms. PMID:20571973

Westrich, Ligia; Sprouse, Jeffrey

2010-07-01

32

Circadian and ultradian rhythms in the crayfish caudal photoreceptor.  

PubMed

The study of circadian clocks in crustaceans has led to the hypothesis of a distributed circadian system of pacemakers. In this review, we investigate the role of the crayfish caudal photoreceptor (CPR) as a candidate to form part of this pacemaking circadian system. Two circadian rhythms are documented for CPR electrical activity. These rhythms correspond to the spontaneous and light-induced discharge of action potentials. The intrinsic characterization of the rhythms is made through the analysis of the firing rate of the corresponding action potentials. The discharges were extracellularly recorded in the isolated 6th abdominal ganglion (AG) in an organ culture kept at constant temperature for up to 5 days. For preparations kept in the dark, spontaneous activity varies in a circadian manner, with a period of 24.7 h and the acrophase at subjective nighttime (2140). For light-induced activity, pulses of constant intensity applied regularly throughout the 24-h cycle show that the firing rate at peak and latency vary rhythmically. The period for this rhythm is 24.24 h and the acrophase is at subjective dawn (0326). Additionally, an ultradian rhythm of a approximately 12-h period was observed for both rhythms. When tested with light pulses of different intensities, the CPR responsiveness at night is almost one log unit greater than in daytime. The effect of temperature on both activities is also described. The phase-shift caused by temperature for these circadian rhythms depends on the application time. These results show that the 6th AG is capable of generating a circadian rhythm of electrical activity in the CPR, which in turn is likely to be part of the crayfish circadian system. A possible interaction of different pacemakers forming the distributed circadian system is also discussed. The role of serotonin as a possible modulator of the CPR electrical activity is documented. In addition, the level of the 5-HT(1A) receptors displays a diurnal rhythm in the 6th AG, with the acrophase at twilight (1849). We suggest that the 5-HT(1A) receptor does participate in this modulation. Finally, the hypothesis of the expression of two circadian oscillators in a single identified neuron is presented. PMID:18563837

Rodríguez-Sosa, Leonardo; Calderón-Rosete, Gabina; Flores, Gonzalo

2008-09-01

33

Characterisation of circadian rhythms of various duckweeds.  

PubMed

The plant circadian clock controls various physiological phenomena that are important for adaptation to natural day-night cycles. Many components of the circadian clock have been identified in Arabidopsis thaliana, the model plant for molecular genetic studies. Recent studies revealed evolutionary conservation of clock components in green plants. Homologues of clock-related genes have been isolated from Lemna gibba and Lemna aequinoctialis, and it has been demonstrated that these homologues function in the clock system in a manner similar to their functioning in Arabidopsis. While clock components are widely conserved, circadian phenomena display diversity even within the Lemna genus. In order to survey the full extent of diversity in circadian rhythms among duckweed plants, we characterised the circadian rhythms of duckweed by employing a semi-transient bioluminescent reporter system. Using a particle bombardment method, circadian bioluminescent reporters were introduced into nine strains representing five duckweed species: Spirodela polyrhiza, Landoltia punctata, Lemna gibba, L. aequinoctialis and Wolffia columbiana. We then monitored luciferase (luc+) reporter activities driven by AtCCA1, ZmUBQ1 or CaMV35S promoters under entrainment and free-running conditions. Under entrainment, AtCCA1::luc+ showed similar diurnal rhythms in all strains. This suggests that the mechanism of biological timing under day-night cycles is conserved throughout the evolution of duckweeds. Under free-running conditions, we observed circadian rhythms of AtCCA1::luc+, ZmUBQ1::luc+ and CaMV35S::luc+. These circadian rhythms showed diversity in period length and sustainability, suggesting that circadian clock mechanisms are somewhat diversified among duckweeds. PMID:24942699

Muranaka, T; Okada, M; Yomo, J; Kubota, S; Oyama, T

2015-01-01

34

Analysis of circadian rhythms in embryonic stem cells.  

PubMed

Recent attention on the early development of circadian rhythms has yielded several avenues of potential study regarding molecular and physiological rhythms in embryonic stem cells (ESCs) and their derivatives. While general guidelines of experimental design are-as always-applicable, there are certain idiosyncrasies with respect to experiments involving circadian rhythms that will be addressed. ESCs provide a number of challenges to the circadian biologist: growth rates are normally much higher than in established cell culture systems, the cells' innate drive towards differentiation and the lack of known synchronizing input pathways are a few examples. Some of these challenges can be addressed post hoc, such as normalization to total RNA or protein for transcript abundance studies. Most others, as outlined here, require special handling of the samples before and during experimentation in order to preserve any potential circadian oscillation that is present. Failure to do so may result in a disruption of endogenous oscillation(s) or, potentially worse, generation of an artificial oscillation that has no biological basis. This chapter begins with cultured ESCs, derived from primary blastocysts or in the form of cell lines, and outlines two methods of measuring circadian rhythms: the 2DG method of measuring glucose uptake (Sokoloff et al. J Neurochem 28:897-916, 1977) and real-time measurement of molecular rhythms using transgenic bioluminescence (Yoo et al. Proc Natl Acad Sci U S A 101:5339-5346, 2004). PMID:25388387

Paulose, Jiffin K; Rucker, Edmund B; Cassone, Vincent M

2015-01-01

35

Cannabinoids and hamster circadian activity rhythms.  

PubMed

Circadian activity rhythms in hamsters are entrained to the daily light:dark cycle by photic information arriving from the retina to the suprachiasmatic nucleus, the site of the master circadian pacemaker in mammals. The effects of light on adjusting the timing of the circadian pacemaker is modified, both positively and negatively, by a variety of transmitter systems, but the effects of endocannabinoids have not been reported. Therefore, in this study we evaluated cannabinoids specific for the cannabinoid type 1 receptor (CB(1)) for their ability to modulate light-induced phase advances in hamster circadian activity rhythms. All compounds were administered intraperitoneally. The CB(1) agonist CP55940 potently inhibited light-induced phase shifts with near 90% inhibition achieved with a dose of 0.125 mg/kg. The inhibitory effect of CP55940 was partially reversed by the CB(1) antagonist LY320135 and completely reversed with 1 mg/kg of the CB(1) antagonist AM 251. Neither LY320135 nor AM 251 had any effect on light-induced phase shifts when administered alone. Further evidence for CB(1) involvement in hamster circadian rhythms was provided by immunohistochemical detection of CB(1) receptors in four separate nuclei comprising the principal components of the hamster circadian system: the suprachiasmatic nucleus, intergeniculate leaflet of the thalamus, and dorsal and median raphe nuclei. Altogether these data indicate that the endocannabinoid system has the capability to modulate circadian rhythms in the hamster and cannabis use should be evaluated for adverse effects on circadian rhythms in humans. PMID:18582849

Sanford, Anna E; Castillo, Elizabeth; Gannon, Robert L

2008-07-30

36

Circadian rhythms in Macaca mulatta monkeys during Bion 11 flight  

NASA Technical Reports Server (NTRS)

Circadian rhythms of primate brain temperature, head and ankle skin temperature, motor activity, and heart rate were studied during spaceflight and on the ground. In space, the circadian rhythms of all the parameters were synchronized with diurnal Zeitgebers. However, in space the brain temperature rhythm showed a significantly more delayed phase angle, which may be ascribed to an increase of the endogenous circadian period.

Alpatov, A. M.; Hoban-Higgins, T. M.; Klimovitsky, V. Y.; Tumurova, E. G.; Fuller, C. A.

2000-01-01

37

Procedures for numerical analysis of circadian rhythms  

PubMed Central

This article reviews various procedures used in the analysis of circadian rhythms at the populational, organismal, cellular and molecular levels. The procedures range from visual inspection of time plots and actograms to several mathematical methods of time series analysis. Computational steps are described in some detail, and additional bibliographic resources and computer programs are listed. PMID:23710111

REFINETTI, ROBERTO; LISSEN, GERMAINE CORNÉ; HALBERG, FRANZ

2010-01-01

38

Circadian rhythms and tumor growth.  

PubMed

Hormone secretion, metabolism, and the cell cycle are under rhythmic control. Lack of rhythmic control has been predicted to lead to uncontrolled proliferation and cancer. Consistent with this prediction are findings that circadian disruption by dim light at night or chronic jet lag accelerates tumor growth in desynchronized animals. Circadian controlled factors such as insulin/IGF-1, glucocorticoids, catecholamines, and melatonin have be implicated in controlling tumor growth in the desynchronized animals. Recent attention has focused on the signaling pathways activated by the circadian controlled factors because these pathways hold the potential for the development of novel strategies for cancer prevention and treatment. PMID:22252116

Greene, Michael W

2012-05-28

39

Peroxiredoxins are conserved markers of circadian rhythms.  

PubMed

Cellular life emerged ?3.7?billion years ago. With scant exception, terrestrial organisms have evolved under predictable daily cycles owing to the Earth's rotation. The advantage conferred on organisms that anticipate such environmental cycles has driven the evolution of endogenous circadian rhythms that tune internal physiology to external conditions. The molecular phylogeny of mechanisms driving these rhythms has been difficult to dissect because identified clock genes and proteins are not conserved across the domains of life: Bacteria, Archaea and Eukaryota. Here we show that oxidation-reduction cycles of peroxiredoxin proteins constitute a universal marker for circadian rhythms in all domains of life, by characterizing their oscillations in a variety of model organisms. Furthermore, we explore the interconnectivity between these metabolic cycles and transcription-translation feedback loops of the clockwork in each system. Our results suggest an intimate co-evolution of cellular timekeeping with redox homeostatic mechanisms after the Great Oxidation Event ?2.5?billion years ago. PMID:22622569

Edgar, Rachel S; Green, Edward W; Zhao, Yuwei; van Ooijen, Gerben; Olmedo, Maria; Qin, Ximing; Xu, Yao; Pan, Min; Valekunja, Utham K; Feeney, Kevin A; Maywood, Elizabeth S; Hastings, Michael H; Baliga, Nitin S; Merrow, Martha; Millar, Andrew J; Johnson, Carl H; Kyriacou, Charalambos P; O'Neill, John S; Reddy, Akhilesh B

2012-05-24

40

Circadian Rhythms in Animals: A Canonical Connections Map  

NSDL National Science Digital Library

Circadian rhythms are near-24-hour endogenous rhythms of behavior and physiology that are a nearly universal feature of eukaryotic life. Genetic and biochemical experiments over the past decade have allowed the construction of a viable working model for the molecular mechanisms underlying circadian rhythm generation in animals. The basic mechanism consists of two intertwined transcription-translation negative feedback loops. One loop--the "positive loop"--controls the rhythmic expression of a well-conserved Per-Arnt-Sim (PAS)-domain-containing positive transcription factor (Clock in Drosophila, and BMAL1, which is also known as MOP3, in the mouse). The second loop--the "negative loop"--controls the expression of another PAS-domain protein (the repressor Period), as well as species-specific repressors (Timeless in Drosophila and Cryptochrome in mice). The loops are intertwined because Period and its binding partners directly repress transcription mediated by Clock and its binding partners (Cycle in Drosophila and BMAL1 in the mouse), whereas Clock:Cycle (or CLOCK:BMAL1) drives the transcription of period and the other repressors, as well as that of repressors of Clock or Bmal1 transcriptional expression. Other factors, including conserved kinases such as Casein kinase I ε (CkIε), have essential functions in the timekeeping mechanism. Remarkably, this mechanism appears to be fundamentally conserved between Drosophila and mammalian circadian clocks. This Canonical Connections Map Pathway describes the basic mechanism underlying circadian signaling, whereas the accompanying specific Pathway Maps for Drosophila and murine circadian mechanisms describe the individual known components of the circadian clock and their mutual interactions. Science Viewpoint R. N. Van Gelder, E. D. Herzog, W. J. Schwartz, P. H. Taghert, Circadian rhythms: In the loop at last. Science 300, 1534-1535 (2003). [Abstract] [Full Text

Russell N. Van Gelder (Washington University Medical School;Department of Ophthalmology and Visual Sciences and Department of Molecular Biology and Pharmacology REV)

2003-08-05

41

Circadian Rhythms in Photosynthesis 1  

PubMed Central

Net carbon assimilation and stomatal conductance to water vapor oscillated repeatedly in red kidney bean, Phaseolus vulgaris L., plants transferred from a natural photoperiod to constant light. In a gas exchange system with automatic regulation of selected environmental and physiological variables, assimilation and conductance oscillated with a free-running period of approximately 24.5 hours. The rhythms in carbon assimilation and stomatal conductance were closely coupled and persisted for more than a week under constant conditions. A rhythm in assimilation occurred when either ambient or intercellular CO2 partial pressure was held constant, demonstrating that the rhythm in assimilation was not entirely the result of stomatal effects on CO2 diffusion. Rhythms in assimilation and conductance were not expressed in plants grown under constant light at a constant temperature, demonstrating that the rhythms did not occur spontaneously but were induced by an external stimulus. In plants grown under constant light with a temperature cycle, a rhythm was entrained in stomatal conductance but not in carbon assimilation, indicating that the oscillators driving the rhythms differed in their sensitivity to environmental stimuli. PMID:16668261

Hennessey, Timothy L.; Field, Christopher B.

1991-01-01

42

A novel animal model linking adiposity to altered circadian rhythms  

Technology Transfer Automated Retrieval System (TEKTRAN)

Researchers have provided evidence for a link between obesity and altered circadian rhythms (e.g., shift work, disrupted sleep), but the mechanism for this association is still unknown. Adipocytes possess an intrinsic circadian clock, and circadian rhythms in adipocytokines and adipose tissue metab...

43

Circadian rhythms synchronize mitosis in Neurospora crassa  

PubMed Central

The cell cycle and the circadian clock communicate with each other, resulting in circadian-gated cell division cycles. Alterations in this network may lead to diseases such as cancer. Therefore, it is critical to identify molecular components that connect these two oscillators. However, molecular mechanisms between the clock and the cell cycle remain largely unknown. A model filamentous fungus, Neurospora crassa, is a multinucleate system used to elucidate molecular mechanisms of circadian rhythms, but not used to investigate the molecular coupling between these two oscillators. In this report, we show that a conserved coupling between the circadian clock and the cell cycle exists via serine/threonine protein kinase-29 (STK-29), the Neurospora homolog of mammalian WEE1 kinase. Based on this finding, we established a mathematical model that predicts circadian oscillations of cell cycle components and circadian clock-dependent synchronized nuclear divisions. We experimentally demonstrate that G1 and G2 cyclins, CLN-1 and CLB-1, respectively, oscillate in a circadian manner with bioluminescence reporters. The oscillations of clb-1 and stk-29 gene expression are abolished in a circadian arrhythmic frqko mutant. Additionally, we show the light-induced phase shifts of a core circadian component, frq, as well as the gene expression of the cell cycle components clb-1 and stk-29, which may alter the timing of divisions. We then used a histone hH1-GFP reporter to observe nuclear divisions over time, and show that a large number of nuclear divisions occur in the evening. Our findings demonstrate the circadian clock-dependent molecular dynamics of cell cycle components that result in synchronized nuclear divisions in Neurospora. PMID:24474764

Hong, Christian I.; Zámborszky, Judit; Baek, Mokryun; Labiscsak, Laszlo; Ju, Kyungsu; Lee, Hyeyeong; Larrondo, Luis F.; Goity, Alejandra; Chong, Hin Siong; Belden, William J.; Csikász-Nagy, Attila

2014-01-01

44

Circadian rhythm asynchrony in man during hypokinesis.  

NASA Technical Reports Server (NTRS)

Posture and exercise were investigated as synchronizers of certain physiologic rhythms in eight healthy male subjects in a defined environment. Four subjects exercised during bed rest. Body temperature (BT), heart rate, plasma thyroid hormone, and plasma steroid data were obtained from the subjects for a 6-day ambulatory equilibration period before bed rest, 56 days of bed rest, and a 10-day recovery period after bed rest. The results indicate that the mechanism regulating the circadian rhythmicity of the cardiovascular system is rigorously controlled and independent of the endocrine system, while the BT rhythm is more closely aligned to the endocrine system.

Winget, C. M.; Vernikos-Danellis, J.; Cronin, S. E.; Leach, C. S.; Rambaut, P. C.; Mack, P. B.

1972-01-01

45

INTRINSIC CIRCADIAN RHYTHMS IN THE CARDIOMYOCYTE  

Technology Transfer Automated Retrieval System (TEKTRAN)

The cardiomyocyte possesses a fully functional circadian clock. Circadian clocks are a set of proteins that generate self-sustained transcriptional positive and negative feedback loops with a free-running period of 24 hours. These intracellular molecular mechanisms confer the selective advantage of ...

46

Temperature compensation and entrainment in circadian rhythms  

NASA Astrophysics Data System (ADS)

To anticipate daily variations in the environment and coordinate biological activities into a daily cycle many organisms possess a circadian clock. In the absence of external time cues the circadian rhythm persists with a period of approximately 24?h. The clock phase can be shifted by single pulses of light, darkness, chemicals, or temperature and this allows entrainment of the clock to exactly 24 h by cycles of these zeitgebers. On the other hand, the period of the circadian rhythm is kept relatively constant within a physiological range of constant temperatures, which means that the oscillator is temperature compensated. The mechanisms behind temperature compensation and temperature entrainment are not fully understood, neither biochemically nor mathematically. Here, we theoretically investigate the interplay of temperature compensation and entrainment in general oscillatory systems. We first give an analytical treatment for small temperature shifts and derive that every temperature-compensated oscillator is entrainable to external small-amplitude temperature cycles. Temperature compensation ensures that this entrainment region is always centered at the endogenous period regardless of possible seasonal temperature differences. Moreover, for small temperature cycles the entrainment region of the oscillator is potentially larger for rectangular pulses. For large temperature shifts we numerically analyze different circadian clock models proposed in the literature with respect to these properties. We observe that for such large temperature shifts sinusoidal or gradual temperature cycles allow a larger entrainment region than rectangular cycles.

Bodenstein, C.; Heiland, I.; Schuster, S.

2012-06-01

47

N-nitrosomelatonin enhances photic synchronization of mammalian circadian rhythms.  

PubMed

Most physiological processes in mammals are synchronized to the daily light:dark cycle by a circadian clock located in the hypothalamic suprachiasmatic nucleus. Signal transduction of light-induced phase advances of the clock is mediated through a neuronal nitric oxide synthase-guanilyl cyclase pathway. We have employed a novel nitric oxide-donor, N-nitrosomelatonin, to enhance the photic synchronization of circadian rhythms in hamsters. The intraperitoneal administration of this drug before a sub-saturating light pulse at circadian time 18 generated a twofold increase of locomotor rhythm phase-advances, having no effect over saturating light pulses. This potentiation was also obtained even when inhibiting suprachiasmatic nitric oxide synthase activity. However, N-nitrosomelatonin had no effect on light-induced phase delays at circadian time 14. The photic-enhancing effects were correlated with an increased suprachiasmatic immunoreactivity of FBJ murine osteosarcoma viral oncogene and period1. Moreover, in vivo nitric oxide release by N-nitrosomelatonin was verified by measuring nitrate and nitrite levels in suprachiasmatic nuclei homogenates. The compound also accelerated resynchronization to an abrupt 6-h advance in the light:dark cycle (but not resynchronization to a 6-h delay). Here, we demonstrate the chronobiotic properties of N-nitrosomelatonin, emphasizing the importance of nitric oxide-mediated transduction for circadian phase advances. PMID:24261470

Baidanoff, Fernando M; Plano, Santiago A; Doctorovich, Fabio; Suárez, Sebastián A; Golombek, Diego A; Chiesa, Juan J

2014-04-01

48

Circadian Rhythms in the Mouse: A Connections Map  

NSDL National Science Digital Library

Genetic and biochemical experiments over the past decade have facilitated the construction of a viable working model for the molecular mechanisms that generate the circadian rhythm in Mus musculus. The basic mechanism consists of two intertwined transcription-translation negative feedback loops. One, the "positive loop," controls the rhythmic expression of a Per-Arnt-Sim (PAS)-domain-containing positive transcription factor, BMAL1 (also called MOP3). The other, the "negative loop," controls the transcription of mPeriod 1 and 2 and mCryptochrome 1 and 2, two families of genes that encode repressor proteins. The loops are intertwined because the proteins mPeriod and mCryptochrome directly repress transcription mediated by the CLOCK:BMAL1 heterodimer, whereas CLOCK:BMAL1 drives transcription of the mPeriod and mCryptochrome genes, as well as that of Rev-erb-alpha, a repressor of Bmal1 expression. Mutations, including the tau mutation in hamsters [encoding Casein kinase I ε (CkIε)], have identified essential functions for other proteins in the timekeeping mechanism. The master pacemaker for circadian rhythms in mice is located in the suprachiasmatic nucleus (SCN) of the hypothalamus. Light cycles can synchronize molecular rhythms in the SCN by stimulating the release of glutamate and the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) from melanopsin-containing retinal ganglion cells. This results in increased transcription of mPeriod genes and a shift in the phase of the clock. This Pathway Map of the murine circadian mechanism describes the individual known components of the mouse circadian clock and their mutual interactions. Science Viewpoint R. N. Van Gelder, E. D. Herzog, W. J. Schwartz, P. H. Taghert, Circadian rhythms: In the loop at last. Science 300, 1534-1535 (2003). [Abstract] [Full Text

Russell N. Van Gelder (Washington University Medical School;Department of Molecular Biology and Pharmacology REV)

2003-08-05

49

Circadian rhythms, sleep, and performance in space  

NASA Technical Reports Server (NTRS)

Maintaining optimal alertness and neurobehavioral functioning during space operations is critical to enable the National Aeronautics and Space Administration's (NASA's) vision "to extend humanity's reach to the Moon, Mars and beyond" to become a reality. Field data have demonstrated that sleep times and performance of crewmembers can be compromised by extended duty days, irregular work schedules, high workload, and varying environmental factors. This paper documents evidence of significant sleep loss and disruption of circadian rhythms in astronauts and associated performance decrements during several space missions, which demonstrates the need to develop effective countermeasures. Both sleep and circadian disruptions have been identified in the Behavioral Health and Performance (BH&P) area and the Advanced Human Support Technology (AHST) area of NASA's Bioastronautics Critical Path Roadmap. Such disruptions could have serious consequences on the effectiveness, health, and safety of astronaut crews, thus reducing the safety margin and increasing the chances of an accident or incident. These decrements oftentimes can be difficult to detect and counter effectively in restrictive operational environments. NASA is focusing research on the development of optimal sleep/wake schedules and countermeasure timing and application to help mitigate the cumulative effects of sleep and circadian disruption and enhance operational performance. Investing research in humans is one of NASA's building blocks that will allow for both short- and long-duration space missions and help NASA in developing approaches to manage and overcome the human limitations of space travel. In addition to reviewing the current state of knowledge concerning sleep and circadian disruptions during space operations, this paper provides an overview of NASA's broad research goals. Also, NASA-funded research, designed to evaluate the relationships between sleep quality, circadian rhythm stability, and performance proficiency in both ground-based simulations and space mission studies, as described in the 2003 NASA Task Book, will be reviewed.

Mallis, M. M.; DeRoshia, C. W.

2005-01-01

50

Vasoactive Intestinal Polypeptide Mediates Circadian Rhythms in Mammalian Olfactory Bulb and Olfaction  

PubMed Central

Accumulating evidence suggests that the olfactory bulbs (OBs) function as an independent circadian system regulating daily rhythms in olfactory performance. However, the cells and signals in the olfactory system that generate and coordinate these circadian rhythms are unknown. Using real-time imaging of gene expression, we found that the isolated olfactory epithelium and OB, but not the piriform cortex, express similar, sustained circadian rhythms in PERIOD2 (PER2). In vivo, PER2 expression in the OB of mice is circadian, approximately doubling with a peak around subjective dusk. Furthermore, mice exhibit circadian rhythms in odor detection performance with a peak at approximately subjective dusk. We also found that circadian rhythms in gene expression and odor detection performance require vasoactive intestinal polypeptide (VIP) or its receptor VPAC2R. VIP is expressed, in a circadian manner, in interneurons in the external plexiform and periglomerular layers, whereas VPAC2R is expressed in mitral and external tufted cells in the OB. Together, these results indicate that VIP signaling modulates the output from the OB to maintain circadian rhythms in the mammalian olfactory system. PMID:24760863

Miller, Jae-eun Kang; Granados-Fuentes, Daniel; Wang, Thomas; Marpegan, Luciano; Holy, Timothy E.

2014-01-01

51

Vasoactive intestinal polypeptide mediates circadian rhythms in mammalian olfactory bulb and olfaction.  

PubMed

Accumulating evidence suggests that the olfactory bulbs (OBs) function as an independent circadian system regulating daily rhythms in olfactory performance. However, the cells and signals in the olfactory system that generate and coordinate these circadian rhythms are unknown. Using real-time imaging of gene expression, we found that the isolated olfactory epithelium and OB, but not the piriform cortex, express similar, sustained circadian rhythms in PERIOD2 (PER2). In vivo, PER2 expression in the OB of mice is circadian, approximately doubling with a peak around subjective dusk. Furthermore, mice exhibit circadian rhythms in odor detection performance with a peak at approximately subjective dusk. We also found that circadian rhythms in gene expression and odor detection performance require vasoactive intestinal polypeptide (VIP) or its receptor VPAC2R. VIP is expressed, in a circadian manner, in interneurons in the external plexiform and periglomerular layers, whereas VPAC2R is expressed in mitral and external tufted cells in the OB. Together, these results indicate that VIP signaling modulates the output from the OB to maintain circadian rhythms in the mammalian olfactory system. PMID:24760863

Miller, Jae-Eun Kang; Granados-Fuentes, Daniel; Wang, Thomas; Marpegan, Luciano; Holy, Timothy E; Herzog, Erik D

2014-04-23

52

Peroxiredoxins are conserved markers of circadian rhythms  

PubMed Central

Summary Cellular life emerged ~3.7 billion years ago. With scant exception, terrestrial organisms have evolved under predictable daily cycles due to the Earth’s rotation. The advantage conferred upon organisms that anticipate such environmental cycles has driven the evolution of endogenous circadian rhythms that tune internal physiology to external conditions. The molecular phylogeny of mechanisms driving these rhythms has been difficult to dissect because identified clock genes and proteins are not conserved across the domains of life: Bacteria, Archaea and Eukaryota. Here we show that oxidation-reduction cycles of peroxiredoxin proteins constitute a universal marker for circadian rhythms in all domains of life, by characterising their oscillations in a variety of model organisms. Furthermore, we explore the interconnectivity between these metabolic cycles and transcription-translation feedback loops of the clockwork in each system. Our results suggest an intimate co-evolution of cellular time-keeping with redox homeostatic mechanisms following the Great Oxidation Event ~2.5 billion years ago. PMID:22622569

Edgar, Rachel S.; Green, Edward W.; Zhao, Yuwei; van Ooijen, Gerben; Olmedo, Maria; Qin, Ximing; Xu, Yao; Pan, Min; Valekunja, Utham K.; Feeney, Kevin A.; Maywood, Elizabeth S.; Hastings, Michael H.; Baliga, Nitin S.; Merrow, Martha; Millar, Andrew J.; Johnson, Carl H.; Kyriacou, Charalambos P.; O’Neill, John S.; Reddy, Akhilesh B.

2012-01-01

53

A Circadian Rhythm Regulating Hyphal Melanization in Cercospora Kikuchii  

Technology Transfer Automated Retrieval System (TEKTRAN)

Circadian rhythms, biochemical or developmental processes with a period length of approximately 24 hours, are thoroughly documented in plants and animals. However, virtually all of what is currently known about circadian rhythms in fungi is derived from the model fungus, Neurospora crassa, including...

54

Drosophila Circadian Rhythms: Stability Robustness Analysis and Model Reduction  

E-print Network

Drosophila Circadian Rhythms: Stability Robustness Analysis and Model Reduction Jorge M. Gonc investigates two models of circadian rhythms in Drosophila: one by Gonze et al. and a more generic model by Vilar et al. that describes the biological clock in Drosophila as well as other organisms. For both

Gonçalves, Jorge

55

Considerations for RNA-seq Analysis of Circadian Rhythms.  

PubMed

Circadian rhythms are daily endogenous oscillations of behavior, metabolism, and physiology. At a molecular level, these oscillations are generated by transcriptional-translational feedback loops composed of core clock genes. In turn, core clock genes drive the rhythmic accumulation of downstream outputs-termed clock-controlled genes (CCGs)-whose rhythmic translation and function ultimately underlie daily oscillations at a cellular and organismal level. Given the circadian clock's profound influence on human health and behavior, considerable efforts have been made to systematically identify CCGs. The recent development of next-generation sequencing has dramatically expanded our ability to study the expression, processing, and stability of rhythmically expressed mRNAs. Nevertheless, like any new technology, there are many technical issues to be addressed. Here, we discuss considerations for studying circadian rhythms using genome scale transcriptional profiling, with a particular emphasis on RNA sequencing. We make a number of practical recommendations-including the choice of sampling density, read depth, alignment algorithms, read-depth normalization, and cycling detection algorithms-based on computational simulations and our experience from previous studies. We believe that these results will be of interest to the circadian field and help investigators design experiments to derive most values from these large and complex data sets. PMID:25662464

Li, Jiajia; Grant, Gregory R; Hogenesch, John B; Hughes, Michael E

2015-01-01

56

[Circadian rhythm disruption and human development].  

PubMed

Ontogenetic developments of rest-activity, sleep-wakefulness, temperature and several hormone rhythms in humans were reviewed. The reported effects of environment on these alterations were also summarized. Then, disorders or conditions which often encounter during early stage of life and reveal circadian rhythm disruptions were described. These disorders or conditions included severe brain damage, visual disturbance, developmental disorders(autistic spectrum disorder and attention deficit/hyperactivity disorder), Rett syndrome, Angelman syndrome, Smith-Magenis syndrome, epilepsy, Yonaki, and inadequate sleep hygiene. Finally, it was emphasized that we should pay special attention on the development of youngsters who showed sleep disturbance during early stage of life with special reference to the later occurrence of developmental disorders. PMID:24437259

Kohyama, Jun

2013-12-01

57

Methods to Record Circadian Rhythm Wheel Running Activity in Mice  

PubMed Central

Forward genetic approaches (phenotype to gene) are powerful methods to identify mouse circadian clock components. The success of these approaches, however, is highly dependent on the quality of the phenotype— specifically, the ability to measure circadian rhythms in individual mice. This article outlines the factors necessary to measure mouse circadian rhythms, including choice of mouse strain, facilities and equipment design and construction, experimental design, high-throughput methods, and finally methods for data analysis. PMID:15817291

Siepka, Sandra M.; Takahashi, Joseph S.

2013-01-01

58

A circadian rhythm regulating hyphal melanization in Cercospora kikuchii.  

PubMed

Many metabolic and developmental processes in fungi are controlled by biological rhythms. Circadian rhythms approximate a daily (24 h) cycle and have been thoroughly studied in the model fungus, Neurospora crassa. However relatively few examples of true circadian rhythms have been documented among other filamentous fungi. In this study we describe a circadian rhythm underlying hyphal melanization in Cercospora kikuchii, an important pathogen of soybean. After growth in light or light : dark cycles, colonies transferred to darkness produced zonate bands of melanized hyphae interspersed with bands of hyaline hyphae. Rhythmic production of bands was remarkably persistent in the absence of external cues, lasting at least 7 d after transfer to darkness, and was compensated over a range of temperatures. As in N. crassa, blue light but not red light was sufficient to entrain the circadian rhythm in C. kikuchii, and a putative ortholog of white collar-1, one of the genes required for light responses in N. crassa, was identified in C. kikuchii. Circadian regulation of melanization is conserved in other members of the genus: Similar rhythms were identified in another field isolate of C. kikuchii as well as field isolates of C. beticola and C. sorghi, but not in wild-type strains of C. zeae-maydis or C. zeina. This report represents the first documented circadian rhythm among Dothideomycete fungi and provides a new opportunity to dissect the molecular basis of circadian rhythms among filamentous fungi. PMID:20943572

Bluhm, Burton H; Burnham, A Michele; Dunkle, Larry D

2010-01-01

59

Circadian rhythms in rheumatology - a glucocorticoid perspective  

PubMed Central

The hypothalamic-pituitary-adrenal (HPA) axis plays an important role in regulating and controlling immune responses. Dysfunction of the HPA axis has been implicated in the pathogenesis of rheumatoid arthritis (RA) and other rheumatic diseases. The impact of glucocorticoid (GC) therapy on HPA axis function also remains a matter of concern, particularly for longer treatment duration. Knowledge of circadian rhythms and the influence of GC in rheumatology is important: on the one hand we aim for optimal treatment of the daily undulating inflammatory symptoms, for example morning stiffness and swelling; on the other, we wish to disturb the HPA axis as little as possible. This review describes circadian rhythms in RA and other chronic inflammatory diseases, dysfunction of the HPA axis in RA and other rheumatic diseases and the recent concept of the hepato-hypothalamic-pituitary-adrenal-renal axis, the problem of adrenal suppression by GC therapy and how it can be avoided, and evidence that chronotherapy with modified release prednisone effective at 02:00 a.m. can inhibit proinflammatory sequelae of nocturnal inflammation better compared with GC administration in the morning but does not increase the risk of HPA axis insufficiency in RA.

2014-01-01

60

A Plastic Clock: How Circadian Rhythms Respond to Environmental Cues in Drosophila  

Microsoft Academic Search

Circadian clocks synchronize the physiology and behavior of most animals with the day to night cycle. A fundamental property\\u000a of the molecular pacemakers generating circadian rhythms is their self-sustained nature: they keep oscillating even under\\u000a constant conditions, with a period close to, but not exactly, 24 h. However, circadian pacemakers have to be sensitive to\\u000a environmental cues to be beneficial. They

Raphaelle Dubruille; Patrick Emery

2008-01-01

61

Synchronisation mechanisms of circadian rhythms in the suprachiasmatic nucleus.  

PubMed

In mammals, the suprachiasmatic nucleus (SCN) of the hypothalamus is considered as the master circadian pacemaker. Each cell in the SCN contains an autonomous molecular clock, and the SCN is composed of multiple single-cell circadian oscillators. The fundamental question is how the individual cellular oscillators, expressing a wide range of periods, interact and assemble to create an integrated pacemaker that can govern behavioural and physiological rhythmicity and be reset by environmental light. The key is that the heterogeneous network formed by the cellular clocks within the SCN must synchronise to maintain timekeeping activity. To study the synchronisation mechanisms and the circadian rhythm generation, we propose a model based on the structural and functional heterogeneity of the SCN. The model is a heterogeneous network of circadian oscillators in which individual oscillators are self-sustained. The authors show that the dorsomedial region can smooth the periodic light-dark (LD) signal curve and affect its wave form. The authors also study the rhythmic process of the circadian oscillators under the effect of the daily LD cycle, including three courses: information afferent inputs, oscillation and information efferent outputs. The numerical simulations are also given to demonstrate the theoretical results. PMID:19292564

Li, Y; Liu, Z; Zhang, J; Wang, R; Chen, L

2009-03-01

62

Circadian Rhythms in Prokaryotes: Luciferase as a Reporter of Circadian Gene Expression in Cyanobacteria  

Microsoft Academic Search

We have used a luciferase reporter gene and continuous automated monitoring of bioluminescence to demonstrate unequivocally that cyanobacteria exhibit circadian behaviors that are fundamentally the same as circadian rhythms of eukaryotes. We also show that these rhythms can be studied by molecular methods in Synechococcus sp. PCC7942, a strain for which genetic transformation is well established. A promoterless segment of

Takao Kondo; Carl A. Strayer; Resham D. Kulkarni; Walter Taylor; Masahiro Ishiura; Susan S. Golden; Carl Hirschie Johnson

1993-01-01

63

Activity in the ferret: oestradiol effects and circadian rhythms  

NASA Technical Reports Server (NTRS)

The present study was conducted to determine whether oestradiol increases activity in the European ferret (Mustela furo), whether this effect is sexually dimorphic, and whether a 24-h rhythm is present in the ferret's daily activity. The activity of male and female adult, postpubertally gonadectomized ferrets was monitored while they were maintained singly on a 13:11 light-dark cycle, before and after implantation with oestradiol-17 beta. Gonadectomized male and female ferrets exhibited equal levels of activity, and neither sex exhibited a significant change in activity following oestradiol implantation. None of the ferrets exhibited a strong circadian rhythm, although weak 24-h rhythms and shorter harmonic rhythms were present. Golden hamsters (Mesocricetus auratus), monitored in an identical manner, exhibited strong circadian rhythms. It was concluded that oestradiol administration may not cause an increase in activity in the ferret, and that this species lacks a strong circadian activity rhythm.

Stockman, E. R.; Albers, H. E.; Baum, M. J.; Wurtman, R. J. (Principal Investigator)

1985-01-01

64

Synergistic interactions between the molecular and neuronal circadian networks drive robust behavioral circadian rhythms in Drosophila melanogaster.  

PubMed

Most organisms use 24-hr circadian clocks to keep temporal order and anticipate daily environmental changes. In Drosophila melanogaster CLOCK (CLK) and CYCLE (CYC) initiates the circadian system by promoting rhythmic transcription of hundreds of genes. However, it is still not clear whether high amplitude transcriptional oscillations are essential for circadian timekeeping. In order to address this issue, we generated flies in which the amplitude of CLK-driven transcription can be reduced partially (approx. 60%) or strongly (90%) without affecting the average levels of CLK-target genes. The impaired transcriptional oscillations lead to low amplitude protein oscillations that were not sufficient to drive outputs of peripheral oscillators. However, circadian rhythms in locomotor activity were resistant to partial reduction in transcriptional and protein oscillations. We found that the resilience of the brain oscillator is depending on the neuronal communication among circadian neurons in the brain. Indeed, the capacity of the brain oscillator to overcome low amplitude transcriptional oscillations depends on the action of the neuropeptide PDF and on the pdf-expressing cells having equal or higher amplitude of molecular rhythms than the rest of the circadian neuronal groups in the fly brain. Therefore, our work reveals the importance of high amplitude transcriptional oscillations for cell-autonomous circadian timekeeping. Moreover, we demonstrate that the circadian neuronal network is an essential buffering system that protects against changes in circadian transcription in the brain. PMID:24698952

Weiss, Ron; Bartok, Osnat; Mezan, Shaul; Malka, Yuval; Kadener, Sebastian

2014-04-01

65

Circadian rhythms and period expression in the Hawaiian cricket genus Laupala  

PubMed Central

Daily activity times and circadian rhythms of crickets have been a subject of behavioral and physiological study for decades. However, recent studies suggest that the underlying molecular mechanism of cricket endogenous clocks differ from the model of circadian rhythm generation in Drosophila. Here we examine the circadian free-running periods of walking and singing in two Hawaiian swordtail cricket species, Laupala cerasina and Laupala paranigra, that differ in the daily timing of mating related activities. Additionally, we examine variation in sequence and daily cycling of the period (per) gene transcript between these species. The species differed significantly in free-running period of singing, but did not differ significantly in the free-running period of locomotion. Like in Drosophila, per transcript abundance showed cycling consistent with a role in circadian rhythm generation. The amino acid differences identified between these species suggest a potential of the per gene in interspecific behavioral variation in Laupala. PMID:23436058

Fergus, Daniel J.; Shaw, Kerry L.

2013-01-01

66

Circadian rhythms and depression: human psychopathology and animal models.  

PubMed

Most organisms (including humans) developed daily rhythms in almost every aspect of their body. It is not surprising that rhythms are also related to affect in health and disease. In the present review we present data that demonstrate the evidence for significant interactions between circadian rhythms and affect from both human studies and animal models research. A number of lines of evidence obtained from human and from animal models research clearly demonstrate relationships between depression and circadian rhythms including (1) daily patterns of depression; (2) seasonal affective disorder; (3) connections between circadian clock genes and depression; (4) relationship between sleep disorders and depression; (5) the antidepressant effect of sleep deprivation; (6) the antidepressant effect of bright light exposure; and (7) the effects of antidepressant drugs on sleep and circadian rhythms. The integration of data suggests that the relationships between the circadian system and depression are well established but the underlying biology of the interactions is far from being understood. We suggest that an important factor hindering research into the underlying mechanisms is the lack of good animal models and we propose that additional efforts in that area should be made. One step in that direction could be the attempt to develop models utilizing diurnal animals which might have a better homology to humans with regard to their circadian rhythms. This article is part of a Special Issue entitled 'Anxiety and Depression'. PMID:21871466

Kronfeld-Schor, Noga; Einat, Haim

2012-01-01

67

Photic and Circadian Regulations of Melatonin Rhythms in Fishes  

Microsoft Academic Search

Photic and circadian regulations of melatonin rhythms in the pineal organ and the retina of several teleosts were studied to investigate the regulatory mechanisms of melatonin rhythms in fishes. In the eyecup preparations of the goldfish, Carassius auratus, both time of day and lighting conditions affected melatonin production, with high melatonin production observed only in the dark-treated group incubated during

Masayuki Iigo; Masayuki Hara; Ritsuko Ohtani-Kaneko; Kazuaki Hirata; Mitsuo Tabata; Katsumi Aida

1997-01-01

68

Original article Effects of light on human circadian rhythms  

E-print Network

suppression of melatonin production. Numerous questions remain regarding the effects of light on the human system. The circadian rhythms (melatonin, cortisol, timing of sleep/wake) of individuals with different enucleated showed free run- ning melatonin and cortisol rhythms. Studies assessing the light

Paris-Sud XI, Université de

69

Development of Heart Rate Circadian Rhythm in Chickens *, R. Akiyamab  

E-print Network

in the chicken, and includes rhythms in daily egg laying, calling at dawn, and daily changes in physiological of heart rate in embryos and hatchlings Fertile eggs of broiler chickens that were brought from a localDevelopment of Heart Rate Circadian Rhythm in Chickens K. Moriyaa *, R. Akiyamab , E.M. Dzialowskic

Burggren, Warren

70

Pinealectomy abolishes the circadian rhythm of migratory restlessness  

Microsoft Academic Search

Pinealectomy of White-throated Sparrows (Zonotrichia albicollis) free-running under constant conditions in dim light abolishes the circadian rhythm of nocturnal spring and fall migratory restlessness (Zugunruhe) as well as the rhythm of summer “daytime” locomotor activity (Pigs. 1 and 2). Rhythmicity persists in sham-operated birds. Pinealectomized birds are synchronized by a light cycle but their activity rhythm decays to arrhythmicity when

J. P. McMillan

1972-01-01

71

Fitness costs of disrupting circadian rhythms in malaria parasites  

PubMed Central

Circadian biology assumes that biological rhythms maximize fitness by enabling organisms to coordinate with their environment. Despite circadian clocks being such a widespread phenomenon, demonstrating the fitness benefits of temporal coordination is challenging and such studies are rare. Here, we tested the consequences—for parasites—of being temporally mismatched to host circadian rhythms using the rodent malaria parasite, Plasmodium chabaudi. The cyclical nature of malaria infections is well known, as the cell cycles across parasite species last a multiple of approximately 24 h, but the evolutionary explanations for periodicity are poorly understood. We demonstrate that perturbation of parasite rhythms results in a twofold cost to the production of replicating and transmission stages. Thus, synchronization with host rhythms influences in-host survival and between-host transmission potential, revealing a role for circadian rhythms in the evolution of host–parasite interactions. More generally, our results provide a demonstration of the adaptive value of circadian rhythms and the utility of using an evolutionary framework to understand parasite traits. PMID:21208950

O'Donnell, Aidan J.; Schneider, Petra; McWatters, Harriet G.; Reece, Sarah E.

2011-01-01

72

Circadian rhythms in the short-tailed shrew, Blarina brevicauda.  

PubMed

Circadian rhythms of wheel running and feeding were measured in the short-tailed shrew. Shrews were strongly nocturnal, and their activity rhythms entrained to both long-day (LD 16:8) and short-day (LD 6:18) photocycles. Under conditions of continuous light (LL) or darkness (DD), the activity rhythms free-ran with average periodicities of 25.1 hours and 24.1 hours, respectively. In LL the level of activity was depressed, and in some cases wheel running was completely inhibited. No significant sex differences were observed in the period or amplitude of the monitored circadian rhythms. All shrews fed throughout the day and night; however, unlike in previous reports, ultradian periods of feeding behavior were not found. The results are related to Aschoff's four observations for the effect of light on activity rhythms in nocturnal rodents. PMID:2255728

Antipas, A J; Madison, D M; Ferraro, J S

1990-08-01

73

Diminished leptin signaling can alter circadian rhythm of metabolic activity and feeding.  

PubMed

Leptin, a hormone mainly produced by fat cells, shows cell-specific effects to regulate feeding and metabolic activities. We propose that an important feature of metabolic dysregulation resulting in obesity is the loss of the circadian rhythm of biopotentials. This was tested in the pan-leptin receptor knockout (POKO) mice newly generated in our laboratory. In the POKO mice, leptin no longer induced pSTAT-3 signaling after intracerebroventricular injection. Three basic phenotypes were observed: the heterozygotes had similar weight and adiposity as the wild-type (WT) mice (>60% of the mice); the homozygotes were either fatter (?30%), or rarely leaner (<5%) than the WT mice. By early adulthood, the POKO mice had higher average body weight and adiposity than their respective same-sex WT littermate controls, and this was consistent among different batches. The homozygote fat POKO showed significant reduction of midline estimating statistic of rhythm of circadian parameters, and shifts of ultradian rhythms. The blunted circadian rhythm of these extremely obese POKO mice was also seen in their physical inactivity, longer feeding bouts, and higher food intake. The extent of obesity correlated with the blunted circadian amplitude, accumulative metabolic and locomotor activities, and the severity of hyperphagia. This contrasts with the heterozygote POKO mice which showed little obesity and metabolic disturbance, and only subtle changes of the circadian rhythm of metabolic activity without alterations in feeding behavior. The results provide a novel aspect of leptin resistance, almost manifesting as an "all or none" phenomenon. PMID:23869060

Hsuchou, Hung; Wang, Yuping; Cornelissen-Guillaume, Germaine G; Kastin, Abba J; Jang, Eunjin; Halberg, Franz; Pan, Weihong

2013-10-01

74

Circadian Rhythms of Ethylene Emission in Arabidopsis1[w  

PubMed Central

Ethylene controls multiple physiological processes in plants, including cell elongation. Consequently, ethylene synthesis is regulated by internal and external signals. We show that a light-entrained circadian clock regulates ethylene release from unstressed, wild-type Arabidopsis (Arabidopsis thaliana) seedlings, with a peak in the mid-subjective day. The circadian clock drives the expression of multiple ACC SYNTHASE genes, resulting in peak RNA levels at the phase of maximal ethylene synthesis. Ethylene production levels are tightly correlated with ACC SYNTHASE 8 steady-state transcript levels. The expression of this gene is controlled by light, by the circadian clock, and by negative feedback regulation through ethylene signaling. In addition, ethylene production is controlled by the TIMING OF CAB EXPRESSION 1 and CIRCADIAN CLOCK ASSOCIATED 1 genes, which are critical for all circadian rhythms yet tested in Arabidopsis. Mutation of ethylene signaling pathways did not alter the phase or period of circadian rhythms. Mutants with altered ethylene production or signaling also retained normal rhythmicity of leaf movement. We conclude that circadian rhythms of ethylene production are not critical for rhythmic growth. PMID:15516515

Thain, Simon C.; Vandenbussche, Filip; Laarhoven, Lucas J.J.; Dowson-Day, Mandy J.; Wang, Zhi-Yong; Tobin, Elaine M.; Harren, Frans J.M.; Millar, Andrew J.; Van Der Straeten, Dominique

2004-01-01

75

Circadian rhythm profiles in women with night eating syndrome.  

PubMed

Night eating syndrome (NES) is characterized by evening hyperphagia and frequent awakenings accompanied by food intake. Patients with NES display a delayed circadian pattern of food intake but retain a normal sleep-wake cycle. These characteristics initiated the current study, in which the phase and amplitude of behavioral and neuroendocrine circadian rhythms in patients with NES were evaluated. Fifteen women with NES (mean age +/- SD, 40.8 +/- 8.7 y) and 14 control subjects (38.6 +/- 9.5 y) were studied in the laboratory for 3 nights, with food intake measured daily. Blood also was collected for 25 h (every 2 h from 0800 to 2000 h, and then hourly from 2100 to 0900 h) and assayed for glucose and 7 hormones (insulin, ghrelin, leptin, melatonin, cortisol, thyroid-stimulating hormone [TSH] and prolactin). Statistical analyses utilized linear mixed-effects cosinor analysis. Control subjects displayed normal phases and amplitudes for all circadian rhythms. In contrast, patients with NES showed a phase delay in the timing of meals, and delayed circadian rhythms for total caloric, fat, and carbohydrate intake. In addition, phase delays of 1.0 to 2.8 h were found in 2 food-regulatory rhythms-leptin and insulin-and in the circadian melatonin rhythm (with a trend for a delay in the circadian cortisol rhythm). In contrast, circulating levels of ghrelin, the primary hormone that stimulates food intake, were phase advanced by 5.2 h. The glucose rhythm showed an inverted circadian pattern. Patients with NES also showed reduced amplitudes in the circadian rhythms of food intake, cortisol, ghrelin, and insulin, but increased TSH amplitude. Thus, patients with NES demonstrated significant changes in the timing and amplitude of various behavioral and physiological circadian markers involved in appetite and neuroendocrine regulation. As such, NES may result from dissociations between central (suprachiasmatic nucleus) timing mechanisms and putative oscillators elsewhere in the central nervous system or periphery, such as the stomach or liver. Considering these results, chronobiologic treatments for NES such as bright light therapy may be useful. Indeed, bright light therapy has shown efficacy in reducing night eating in case studies and should be evaluated in controlled clinical trials. PMID:19150931

Goel, Namni; Stunkard, Albert J; Rogers, Naomi L; Van Dongen, Hans P A; Allison, Kelly C; O'Reardon, John P; Ahima, Rexford S; Cummings, David E; Heo, Moonseong; Dinges, David F

2009-02-01

76

An ASMT variant associated with bipolar disorder influences sleep and circadian rhythms: a pilot study  

E-print Network

1 An ASMT variant associated with bipolar disorder influences sleep and circadian rhythms: a pilot references) 10 Keywords: sleep; actigraphy; melatonin; ASMT gene; bipolar disorder; circadian rhythms.12103 #12;2 ABSTRACT Patients with bipolar disorder (BD) experience persistent circadian rhythm

Paris-Sud XI, Université de

77

Loss of dopamine disrupts circadian rhythms in a mouse model of Parkinson's disease.  

PubMed

Although a wide range of physiological functions regulated by dopamine (DA) display circadian variations, the role of DA in the generation and/or modulation of these rhythms is unknown. In Parkinson's disease (PD) patients, in addition to the classical motor symptoms, disturbances of the pattern of daily rest/wake cycles are common non-motor symptoms. We investigated daily and circadian rhythms of rest/activity behaviors in a transgenic MitoPark mouse model with selective inactivation of mitochondrial transcription factor A (Tfam) resulting in a slow and progressive degeneration of DA neurons in midbrain structures. Correlated with this, MitoPark mice show a gradual reduction in locomotor activity beginning at about 20weeks of age. In a light-dark cycle, MitoPark mice exhibit a daily pattern of rest/activity rhythms that shows an age-dependent decline in both the amplitude and the stability of the rhythm, coupled with an increased fragmentation of day/night activities. When the circadian system is challenged by exposure to constant darkness or constant light conditions, control littermates retain a robust free-running circadian locomotor rhythm, whereas in MitoPark mice, locomotor rhythms are severely disturbed or completely abolished. Re-exposure to a light/dark cycle completely restores daily locomotor rhythms. MitoPark mice and control littermates express similar masking behaviors under a 1h light/1h dark regime, suggesting that the maintenance of a daily pattern of rest/activity in arrhythmic MitoPark mice can be attributed to the acute inhibitory and stimulatory effects of light and darkness. These results imply that, in addition to the classical motor abnormalities observed in PD, the loss of the midbrain DA neurons leads to impairments of the circadian control of rest/activity rhythms. PMID:25171792

Fifel, Karim; Cooper, Howard M

2014-11-01

78

Light as a central modulator of circadian rhythms, sleep and affect.  

PubMed

Light has profoundly influenced the evolution of life on earth. As widely appreciated, light enables us to generate images of our environment. However, light - through intrinsically photosensitive retinal ganglion cells (ipRGCs) - also influences behaviours that are essential for our health and quality of life but are independent of image formation. These include the synchronization of the circadian clock to the solar day, tracking of seasonal changes and the regulation of sleep. Irregular light environments lead to problems in circadian rhythms and sleep, which eventually cause mood and learning deficits. Recently, it was found that irregular light can also directly affect mood and learning without producing major disruptions in circadian rhythms and sleep. In this Review, we discuss the indirect and direct influence of light on mood and learning, and provide a model for how light, the circadian clock and sleep interact to influence mood and cognitive functions. PMID:24917305

LeGates, Tara A; Fernandez, Diego C; Hattar, Samer

2014-07-01

79

Circadian rhythms of temperature and activity in obese and lean Zucker rats  

NASA Technical Reports Server (NTRS)

The circadian timing system is important in the regulation of feeding and metabolism, both of which are aberrant in the obese Zucker rat. This study tested the hypothesis that these abnormalities involve a deficit in circadian regulation by examining the circadian rhythms of body temperature and activity in lean and obese Zucker rats exposed to normal light-dark cycles, constant light, and constant dark. Significant deficits in both daily mean and circadian amplitude of temperature and activity were found in obese Zucker female rats relative to lean controls in all lighting conditions. However, the circadian period of obese Zucker rats did not exhibit differences relative to lean controls in either of the constant lighting conditions. These results indicate that although the circadian regulation of temperature and activity in obese Zucker female rats is in fact depressed, obese rats do exhibit normal entrainment and pacemaker functions in the circadian timing system. The results suggest a deficit in the process that generates the amplitude of the circadian rhythm.

Murakami, D. M.; Horwitz, B. A.; Fuller, C. A.

1995-01-01

80

Observer Design for a Core Circadian Rhythm Network  

PubMed Central

The paper investigates the observer design for a core circadian rhythm network in Drosophila and Neurospora. Based on the constructed highly nonlinear differential equation model and the recently proposed graphical approach, we design a rather simple observer for the circadian rhythm oscillator, which can well track the state of the original system for various input signals. Numerical simulations show the effectiveness of the designed observer. Potential applications of the related investigations include the real-world control and experimental design of the related biological networks. PMID:25121122

Zhang, Yuhuan

2014-01-01

81

Genetics of circadian rhythms and mood spectrum disorders.  

PubMed

Mood spectrum disorders (bipolar disorder, recurrent depressive disorder and seasonal affective disorder) are accompanied by circadian deregulations, which can occur during acute mood episodes as well as during euthymic periods, and are particularly common among bipolar patients in remission. This suggests that altered circadian rhythms may be biological markers of these disorders. Rhythm dysfunctions have been observed in mood disorder patients by using actigraphic measures and by assessing social metric rhythms, diurnal preferences and melatonin secretion. Since many of these markers are heritable and therefore driven by clock genes, these genes may represent susceptibility factors for mood spectrum disorders. Indeed, several genetic association studies have suggested that certain circadian gene variants play a role in susceptibility to these disorders. Such connections to circadian genes such as CLOCK, ARNTL1, NPAS2, PER3 and NR1D1 have been repeatedly demonstrated for bipolar disorders, and to a lesser extent for recurrent depressive disorders and seasonal affective disorders. The study of circadian phenotypes and circadian genes in mood spectrum disorders represents a major field of research that may yet reveal the pathophysiological determinants of these disorders. PMID:21835597

Etain, B; Milhiet, V; Bellivier, F; Leboyer, M

2011-09-01

82

Circadian Rhythms in Anesthesia and Critical Care Medicine: Potential Importance of Circadian Disruptions.  

PubMed

The rotation of the earth and associated alternating cycles of light and dark-the basis of our circadian rhythms-are fundamental to human biology and culture. However, it was not until 1971 that researchers first began to describe the molecular mechanisms for the circadian system. During the past few years, groundbreaking research has revealed a multitude of circadian genes affecting a variety of clinical diseases, including diabetes, obesity, sepsis, cardiac ischemia, and sudden cardiac death. Anesthesiologists, in the operating room and intensive care units, manage these diseases on a daily basis as they significantly affect patient outcomes. Intriguingly, sedatives, anesthetics, and the intensive care unit environment have all been shown to disrupt the circadian system in patients. In the current review, we will discuss how newly acquired knowledge of circadian rhythms could lead to changes in clinical practice and new therapeutic concepts. PMID:25294583

Brainard, Jason; Gobel, Merit; Bartels, Karsten; Scott, Benjamin; Koeppen, Michael; Eckle, Tobias

2014-10-01

83

Circadian Rhythms: In the Loop at Last  

NSDL National Science Digital Library

This Viewpoint compares and contrasts the circadian clocks of mammals and of Drosophila, emphasizing how different players are used to create the same basic script. Both the general script and the specific details of the murine and Drosophila circadian pathways are available at Science's Signal Transduction Knowledge Environment Connections Maps.

Russell N. Van Gelder (Washington University;Department of Ophthalmology and Visual Sciences/Department of Molecular Biology and Pharmacology); Erik D. Herzog (Washington University;Department of Biology); William Schwartz (University of Massachusetts Medical School;Department of Neurology); Paul Taghert (Washington University;Department of Anatomy and Neurobiology)

2003-06-06

84

Circadian and ultradian influences on dreaming: A dual rhythm model  

Microsoft Academic Search

The dual rhythm model of dreaming states that, under high sensory thresholds, heightened general cortical activation common to both REM\\/NREM and circadian-driven activation cycles sums to produce the main characteristics of dreaming. In addition, the unique pattern of regional brain activation characteristic of REM sleep amplifies the emotional intensity of the dream. Subjects were awakened from REM and NREM sleep

Erin J. Wamsley; Yasutaka Hirota; Matthew A. Tucker; Mark R. Smith; John S. Antrobus

2007-01-01

85

ANIMAL RESPONSES TO CIRCADIAN RHYTHMS IN FORAGE QUALITY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Net photosynthesis and respiration in growing plants cause a circadian rhythm in forage quality. Soluble sugar concentrations increase in plants during the day causing a dilution in ADF and NDF. Herbivores show a strong preference for afternoon (PM) vs morning (AM) harvested forage. Cattle, sheep, g...

86

Biomarker circadian rhythm profiles in critically ill mechanically ventilated patients  

Microsoft Academic Search

Objective: To explore the natural trajectory of core body temperature (CBT) and cortisol (CORT) circadian rhythms in mechanically ventilated intensive care unit (MV ICU) patients. ^ Design: Prospective, observational, time-series pilot study. ^ Setting: Medical-surgical and pulmonary ICUs in a tertiary care hospital. ^ Sample: Nine (F = 3, M = 6) adults who were mechanically ventilated within 12 hrs

Mary Anne Vincent

2011-01-01

87

Circadian rhythm and cell population growth June 17, 2010  

E-print Network

entrainment perturbations, of the central hypothalamic circadian clock in tumor-bearing mice leads proliferation. It has been observed in tumor-bearing laboratory rodents that a severe disruption of these physio- logical rhythms results in accelerated tumor growth. The question of accurately representing the control

88

Circadian and ultradian influences on dreaming: a dual rhythm model.  

PubMed

The dual rhythm model of dreaming states that, under high sensory thresholds, heightened general cortical activation common to both REM/NREM and circadian-driven activation cycles sums to produce the main characteristics of dreaming. In addition, the unique pattern of regional brain activation characteristic of REM sleep amplifies the emotional intensity of the dream. Subjects were awakened from REM and NREM sleep once near the nadir of the core body temperature rhythm, where circadian-driven cortical activation was assumed to be low, and again in the late morning, where this activation was presumed to be high. As predicted, changes in the central characteristics of dream reports mirrored REM/NREM and circadian-driven fluctuations in general activation, while at the same time, the regional activation pattern unique to REM sleep amplified dream emotionality selectively in REM reports. PMID:17208651

Wamsley, Erin J; Hirota, Yasutaka; Tucker, Matthew A; Smith, Mark R; Antrobus, John S

2007-01-01

89

CIRCADIAN RHYTHMS Marking Time for a Kingdom  

NSDL National Science Digital Library

The author provides perspective on a study reported on page 483 of this issue. Findings from this study identifying a crucial circadian gene in hamsters represents "a major breakthrough for time-conscious mammals".

Michael Young (The Rockefeller University;Laboratory of Genetics and National Science Foundation Center for Biological Timing)

2000-04-21

90

Light and Gravity Effects on Circadian Rhythms of Rhesus Macaques  

NASA Technical Reports Server (NTRS)

Temporal integration of a biological organism's physiological, behavioral and biochemical systems depends upon its circadian timing system. The endogenous period of this timing system is typically synchronized to the 24- hour day by environmental cues. The daily alternation of light and dark has long been known as one of the most potent environmental synchronizers influencing the circadian timing system. Alterations in the lighting environment (length or intensity of light exposure) can also affect the homeostatic state of the organism. A series of experiments was performed using rhesus monkeys with the objective of defining the fundamental properties of the circadian rhythm of body temperature. Three major experiments were performed in addition to several preliminary studies. These experiments explored 1.) the response of the rhesus body temperature rhythm to varying day length and light intensity; 2.) the response of the body temperature rhythm to light exposure as a function of time of day; and 3.) the characteristics of the metabolic heat production rhythm which is responsible for the daily cycle in body temperature. Results of these three completed experiments will be reported here. In addition, preliminary experiments were also performed in social entrainment of rhesus circadian rhythms and the properties of rhesus body temperature rhythms in constant conditions, where no external time cues were provided. Four adult male rhesus monkeys served as subjects in all experiments. All experiments were performed at the California Regional Primate Research Center. Each animal was implanted with a biotelemetry unit that measured deep body temperature. All surgeries were performed by a board certified veterinary surgeon under sterile conditions. The biotelemetry implants also provided an index of activity level in each animal. For metabolic heat production measurements, oxygen consumption and carbon dioxide production were measured and the caloric equivalent of these was calculated. Specific methodologies are described in detail.

Fuller, Charles

1997-01-01

91

Circadian Clock Proteins in Prokaryotes: Hidden Rhythms?  

PubMed Central

Circadian clock genes are vital features of eukaryotes that have evolved such that organisms can adapt to our planet's rotation in order to anticipate the coming day or night as well as unfavorable seasons. This circadian clock uses oscillation as a timekeeping element. However, circadian clock mechanisms exist also in prokaryotes. The circadian clock of Cyanobacteria is well studied. It is regulated by a cluster of three genes: kaiA, kaiB, and kaiC. In this review, we will discuss the circadian system in cyanobacteria, and provide an overview and updated phylogenetic analysis of prokaryotic organisms that contain the main circadian genes. It is evident that the evolution of the kai genes has been influenced by lateral transfers but further and deeper studies are needed to get an in depth understanding of the exact evolutionary history of these genes. Interestingly, Legionella pneumophila an environmental bacterium and opportunistic human pathogen that parasitizes protozoa in fresh water environments also contains kaiB and kaiC, but their functions are not known. All of the residues described for the biochemical functions of the main pacemaker KaiC in Synechococcus elongatus are also conserved in the L. pneumophila KaiC protein. PMID:21687756

Loza-Correa, Maria; Gomez-Valero, Laura; Buchrieser, Carmen

2010-01-01

92

Sleep and Circadian Rhythms in Four Orbiting Astronauts  

NASA Technical Reports Server (NTRS)

INTRODUCTION The study of human sleep and circadian rhythms in space has both operational and scientific significance. Operationally, U.S. Spaceflight is moving away from brief missions with durations of less than one week. Most space shuttle missions now last two weeks or more, and future plans involving space stations, lunar bases and interplanetary missions all presume that people will be living away from the gravity and time cues of earth for months at a time. Thus, missions are moving away from situations where astronauts can "tough it out" for comparatively brief durations, to situations where sleep and circadian disruptions are likely to become chronic, and thus resistant to short term pharmacological or behavioral manipulations. As well as the operational significance, there is a strong theoretical imperative for studying the sleep and circadian rhythms of people who are removed from the gravity and time cues of earth. Like other animals, in humans, the Circadian Timekeeping System (CTS) is entrained to the correct period (24h) and temporal orientation by various time cues ("zeitgebers"), the most powerful of which is the alternation of daylight and darkness. In leaving Earth, astronauts are removing themselves from the prime zeitgeber of their circadian system -- the 24h alternation of daylight and darkness.

Monk, Timothy H.; Buysse, Daniel J.; Billy, Bart D.; Kennedy, Kathy S.; Willrich, Linda M.

1999-01-01

93

Recording and analysis of circadian rhythms in running-wheel activity in rodents.  

PubMed

When rodents have free access to a running wheel in their home cage, voluntary use of this wheel will depend on the time of day. Nocturnal rodents, including rats, hamsters, and mice, are active during the night and relatively inactive during the day. Many other behavioral and physiological measures also exhibit daily rhythms, but in rodents, running-wheel activity serves as a particularly reliable and convenient measure of the output of the master circadian clock, the suprachiasmatic nucleus (SCN) of the hypothalamus. In general, through a process called entrainment, the daily pattern of running-wheel activity will naturally align with the environmental light-dark cycle (LD cycle; e.g. 12 hr-light:12 hr-dark). However circadian rhythms are endogenously generated patterns in behavior that exhibit a ~24 hr period, and persist in constant darkness. Thus, in the absence of an LD cycle, the recording and analysis of running-wheel activity can be used to determine the subjective time-of-day. Because these rhythms are directed by the circadian clock the subjective time-of-day is referred to as the circadian time (CT). In contrast, when an LD cycle is present, the time-of-day that is determined by the environmental LD cycle is called the zeitgeber time (ZT). Although circadian rhythms in running-wheel activity are typically linked to the SCN clock, circadian oscillators in many other regions of the brain and body could also be involved in the regulation of daily activity rhythms. For instance, daily rhythms in food-anticipatory activity do not require the SCN and instead, are correlated with changes in the activity of extra-SCN oscillators. Thus, running-wheel activity recordings can provide important behavioral information not only about the output of the master SCN clock, but also on the activity of extra-SCN oscillators. Below we describe the equipment and methods used to record, analyze and display circadian locomotor activity rhythms in laboratory rodents. PMID:23380887

Verwey, Michael; Robinson, Barry; Amir, Shimon

2013-01-01

94

Recording and Analysis of Circadian Rhythms in Running-wheel Activity in Rodents  

PubMed Central

When rodents have free access to a running wheel in their home cage, voluntary use of this wheel will depend on the time of day1-5. Nocturnal rodents, including rats, hamsters, and mice, are active during the night and relatively inactive during the day. Many other behavioral and physiological measures also exhibit daily rhythms, but in rodents, running-wheel activity serves as a particularly reliable and convenient measure of the output of the master circadian clock, the suprachiasmatic nucleus (SCN) of the hypothalamus. In general, through a process called entrainment, the daily pattern of running-wheel activity will naturally align with the environmental light-dark cycle (LD cycle; e.g. 12 hr-light:12 hr-dark). However circadian rhythms are endogenously generated patterns in behavior that exhibit a ~24 hr period, and persist in constant darkness. Thus, in the absence of an LD cycle, the recording and analysis of running-wheel activity can be used to determine the subjective time-of-day. Because these rhythms are directed by the circadian clock the subjective time-of-day is referred to as the circadian time (CT). In contrast, when an LD cycle is present, the time-of-day that is determined by the environmental LD cycle is called the zeitgeber time (ZT). Although circadian rhythms in running-wheel activity are typically linked to the SCN clock6-8, circadian oscillators in many other regions of the brain and body9-14 could also be involved in the regulation of daily activity rhythms. For instance, daily rhythms in food-anticipatory activity do not require the SCN15,16 and instead, are correlated with changes in the activity of extra-SCN oscillators17-20. Thus, running-wheel activity recordings can provide important behavioral information not only about the output of the master SCN clock, but also on the activity of extra-SCN oscillators. Below we describe the equipment and methods used to record, analyze and display circadian locomotor activity rhythms in laboratory rodents. PMID:23380887

Verwey, Michael; Robinson, Barry; Amir, Shimon

2013-01-01

95

Circadian rhythms in handwriting kinematics and legibility  

Microsoft Academic Search

The aim of the present study was to analyze the circadian rhythmicity in handwriting kinematics and legibility and to compare the performance between Dutch and German writers. Two subject groups underwent a 40h sleep deprivation protocol under Constant Routine conditions either in Groningen (10 Dutch subjects) or in Berlin (9 German subjects). Both groups wrote every 3h a test sentence

Isabelle Jasper; Marijke Gordijn; Andreas Häußler; Joachim Hermsdörfer

2011-01-01

96

Circadian rhythms affect electroretinogram, compound eye color, striking behavior and locomotion of the praying mantis Hierodula patellifera.  

PubMed

Many behaviors and physiological processes oscillate with circadian rhythms that are synchronized to environmental cues (e.g. light onset), but persist with periods of ~24 h in the absence of such cues. We used a multilevel experimental approach to assess whether circadian rhythms modulate several aspects of the visual physiology and behavior of the praying mantis Hierodula patellifera. We used electroretinograms (ERGs) to assess compound eye sensitivity, colorimetric photographic analyses to assess compound eye color changes (screening pigment migration), behavioral assays of responsiveness to computer-generated prey-like visual stimuli and analyses of locomotor activity patterns on a modified treadmill apparatus. Our results indicate that circadian clocks control and/or modulate each of the target behaviors. Strong rhythms, persisting under constant conditions, with periods of ~24 h were evident in photoreceptor sensitivity to light, appetitive responsiveness to prey-like stimuli and gross locomotor activity. In the first two cases, responsiveness was highest during the subjective night and lowest during the subjective day. Locomotor activity was strongly clustered around the transition time from day to night. In addition, pigment migration and locomotor behavior responded strongly to light:dark cycles and anticipated the light-dark transition, suggesting that the circadian clocks modulating both were entrained to environmental light cues. Together, these data indicate that circadian rhythms operate at the cellular, cellular systems and organismal level in H. patellifera. Our results represent an intriguing first step in uncovering the complexities of circadian rhythms in the Mantodea. PMID:25214491

Schirmer, Aaron E; Prete, Frederick R; Mantes, Edgar S; Urdiales, Andrew F; Bogue, Wil

2014-11-01

97

Arterioscler Thromb Vasc Biol . Author manuscript Nuclear receptors linking circadian rhythms and cardiometabolic control  

E-print Network

; Animals ; Cardiovascular Agents ; therapeutic use ; Cardiovascular Diseases ; drug therapy ; genetics between circadian disorders and altered metabolic responses and cardiovascular events. Shiftwork ; metabolism ; physiopathology ; Cardiovascular System ; drug effects ; metabolism ; Circadian Rhythm ; drug

Paris-Sud XI, Université de

98

[Arterial blood pressure circadian rhythm: significance and clinical implications].  

PubMed

Arterial blood pressure circadian rhythm: significance and clinical implications Arterial blood pressure exhibits a circadian rhythm characterized by a decrease during the sleep period and a steep increase in the early morning hours that can be characterized by 24 h ambulatory blood pressure monitoring (ABPM). The absence of a nocturnal dipping or an excessive morning surge, commonly observed in hypertensive patients, is associated with an increased cardiovascular and renal risk. Numerous studies show that a better control of nocturnal blood pressure can be obtained by the administration of anti-hypertensive medication at the evening time, improving microalbuminuria, left heart hypertrophy, or arterial intima-media thickness, but only one study has so far demonstrated a decrease of major cardiovascular events. In this context, the decision on restoring or not the nocturnal dipping should be left to the judgement of the clinician, and applied in an individual manner to each patient. PMID:23029984

Gonzalez Rodriguez, E; Hernandez, A; Dibner, C; Koehler Ballan, B; Pechère-Bertschi, A

2012-09-12

99

Sex Differences in Behavioral Circadian Rhythms in Laboratory Rodents  

PubMed Central

There is a strong bias in basic research on circadian rhythms toward the use of only male animals in studies. Furthermore, of the studies that use female subjects, many use only females and do not compare results between males and females. This review focuses on behavioral aspects of circadian rhythms that differ between the sexes. Differences exist in the timing of daily onset of activity, responses to both photic and non-photic stimuli, and in changes across the lifespan. These differences may reflect biologically important traits that are ecologically relevant and impact on a variety of responses to behavioral and physiological challenges. Overall, more work needs to be done to investigate differences between males and females as well as differences that are the result of hormonal changes across the lifespan.

Krizo, Jessica A.; Mintz, Eric M.

2014-01-01

100

Entrainment of Circadian Rhythms by Sound in Passer domesticus  

Microsoft Academic Search

The circadian locomotor rhythm of house sparrows was entrained by a sound stimulus. The birds were maintained at a constant temperature in dim green light. The entraining agent was 41\\/2 hours of tape-recorded bird song played each day. Variations in the response to this stimulus have been correlated with individual variations in free-running period. This is the first clear demonstration

Michael Menaker; Arnold Eskin

1966-01-01

101

Circadian rhythms in the green sunfish retina  

Microsoft Academic Search

We investigatedthe occurrence of circadianrhythms in retino- motor movements and retinalsensitivity in the green sunfish,Lepomis cyanellus. When green sunfish were kept in constant darkness, cone photoreceptors exhibited circadian retinomotor movements ;rod photoreceptors and retinal pigment epithelium (RPE) pigment granules did not.Cones elongated during subjectivenightand contracted during subjectiveday .These resultscorroborate those of Burnside and Ackland (1984 .Investigative Ophthalmology and Visual Science.25

ALLEN DEARRY; ROBERT B. BARLOW

1987-01-01

102

The circadian rhythm of the perinatal mortality rate in Switzerland.  

PubMed

The authors examine the relation between the perinatal mortality rate (PMR), birth weight in four categories, and hour of birth throughout the week in Switzerland, using data on 672,013 births and 5,764 perinatal deaths recorded between 1979 and 1987. From Monday to Friday, the PMR follows a circadian rhythm with a regular increase from early morning to evening, with a peak for babies born between 7 and 8 p.m. This pattern of variation has two main components: The circadian rhythms for the proportion of births in the four weight categories and the PMR circadian rhythm for babies weighing more than 2.5 kg. According to a cosinor model, which describes about 40% of the total variation in the PMR, the most important determinants are changes in the proportions of births: Low birth weight increases toward the afternoon and night. Mechanisms underlying the weight-specific timing of birth are discussed, including time selection of birth according to obstetric risks, the direct effect of neonatal and obstetric care, and chronobiologic behavior. PMID:1585906

Ruffieux, C; Marazzi, A; Paccaud, F

1992-04-15

103

Familial Circadian Rhythm Disorder in the Diurnal Primate, Macaca mulatta  

PubMed Central

In view of the inverse temporal relationship of central clock activity to physiological or behavioral outputs in diurnal and nocturnal species, understanding the mechanisms and physiological consequences of circadian disorders in humans would benefit from studies in a diurnal animal model, phylogenetically close to humans. Here we report the discovery of the first intrinsic circadian disorder in a family of diurnal non-human primates, the rhesus monkey. The disorder is characterized by a combination of delayed sleep phase, relative to light-dark cycle, mutual desynchrony of intrinsic rhythms of activity, food intake and cognitive performance, enhanced nighttime feeding or, in the extreme case, intrinsic asynchrony. The phenotype is associated with normal length of intrinsic circadian period and requires an intact central clock, as demonstrated by an SCN lesion. Entrainment to different photoperiods or melatonin administration does not eliminate internal desynchrony, though melatonin can temporarily reinstate intrinsic activity rhythms in the animal with intrinsic asynchrony. Entrainment to restricted feeding is highly effective in animals with intrinsic or SCN lesion-induced asynchrony. The large isolated family of rhesus macaques harboring the disorder provides a powerful new tool for translational research of regulatory circuits underlying circadian disorders and their effective treatment. PMID:22413014

Zhdanova, Irina V.; Masuda, Ken; Bozhokin, Sergey V.; Rosene, Douglas L.; González-Martínez, Janis; Schettler, Steven; Samorodnitsky, Eric

2012-01-01

104

Implicit Associations Have a Circadian Rhythm  

PubMed Central

The current study shows that people's ability to inhibit implicit associations that run counter to their explicit views varies in a circadian pattern. The presence of this rhythmic variation suggests the involvement of a biological process in regulating automatic associations—specifically, with the current data, associations that form undesirable social biases. In 1998, Greenwald, McGhee, and Schwartz introduced the Implicit Association Test as a means of measuring individual differences in implicit cognition. The IAT is a powerful tool that has become widely used. Perhaps most visibly, studies employing the IAT demonstrate that people generally hold implicit biases against social groups, which often conflict with their explicitly held views. The IAT engages inhibitory processes similar to those inherent in self-control tasks. Because the latter processes are known to be resource-limited, we considered whether IAT scores might likewise be resource dependent. Analyzing IAT performance from over a million participants across all times of day, we found a clear circadian pattern in scores. This finding suggests that the IAT measures not only the strength of implicit associations, but also the effect of variations in the physiological resources available to inhibit their undesirable influences on explicit behavior. PMID:25365254

Zadra, Jonathan R.; Proffitt, Dennis R.

2014-01-01

105

Circadian rhythms in effects of hypnotics and sleep inducers.  

PubMed

Chronopharmacology involves the investigation of drug effects as a function of biological time and the investigation of drug effects on rhythm characteristics. Three new concepts must be considered: (a) the chronokinetics of a drug, embracing rhythmic (circadian) changes in drug bioavailability (or pharmacokinetics) and its excretion (urinary among others); (b) the chronaesthesia of a biosystem to a drug, i.e. circadian changes in the susceptibility of any biosystem to a drug (including organ systems, parasites, etc.); skin and bronchial chronaesthesia to various agents have been documented in man; and (c) the chronergy of a drug, taking into consideration its chronokinetics and the chronaesthesia of the involved organismic biosystems. The term chronergy includes rhythmic changes in the overall effects and in the effectiveness of some drugs. Clinical chronopharmacology is useful for solving problems of drug optimization, i.e. enhancing the desired efficiency of a drug and reducing its undesired effects. Circadian rhythms can be demonstrated in various effects of drugs on sleep, anaesthesia and related processes. For example, in the rat the duration of sleep induced by substances such as pentobarbital, hexobarbital, Althesin (alphaxadone and alphadoline in castor oil) is circadian system stage-dependent. Time-dependent changes of liver enzymes (e.g. hexobarbital oxidase) play a role in these circadian rhythms. The clinical chronopharmacokinetics of benzodiazepines have been documented in man. Chronopharmacologic methods can be used to study desired and undesired hypnotic effects of substances. Such is the case of new antihistamines (anti-H1), which do not induce sleepiness, in either acute or chronic administration. Pertinent also is the problem of intolerance to shift-work. Intolerant shift-workers are subject to internal desynchronization between at least two rhythms (e.g. activity-rest cycle and body temperature). Clinically these workers suffer from sleep disturbances, persistent fatigue and are regular users of sleeping pills, which is also a symptom of intolerance. However, over the long-term, these drugs are of no help to intolerant shift-workers. PMID:3514493

Reinberg, A

1986-01-01

106

Circadian rhythms in myocardial metabolism and contractile function; influence of workload and oleate  

Technology Transfer Automated Retrieval System (TEKTRAN)

Multiple extra-cardiac stimuli, such as workload and circulating nutrients (e.g., fatty acids), known to influence myocardial metabolism and contractile function exhibit marked circadian rhythms. The aim of the present study was to investigate whether the rat heart exhibits circadian rhythms in its ...

107

A ticking clock: Performance analysis of a Circadian rhythm with stochastic process  

E-print Network

that with a bounded model, the clock phase can be affected by modifying the ability to manufacture some proteins. 1 fluctuations in the concentration of a protein within the cell. The exact concentration of protein provides problem, that of capturing and reproducing the Circadian rhythm. A Circadian rhythm provides cells

Imperial College, London

108

Neonatal monosodium glutamate treatment prevents effects of constant light on circadian temperature rhythms of adult rats  

Microsoft Academic Search

Housing rats under continuous illumination (LL) disrupts circadian rhythms controlled by a pacemaker located in the hypothalamic suprachiasmatic nucleus (SCN). The neural mechanisms underlying this effect are not well understood. The present study examined the effects of LL on circadian rhythms and on light-induced expression of Fos protein in the SCN, intergeniculate leaflet (IGL), and ventrolateral geniculate nucleus (vLGN) in

K. Edelstein; J. G. Pfaus; B. Rusak; S. Amir

1995-01-01

109

Circadian rhythms on hypothalamicpituitaryadrenal axis hormones and cytokines of collagen induced arthritis in rats  

E-print Network

Circadian rhythms on hypothalamic­pituitary­adrenal axis hormones and cytokines of collagen induced whether circadian rhythms of the hormones of the hypothalamic­pituitary­adrenal (HPA) axis are associated hormone (ACTH) and corticosterone, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and IL-1

Li, Shao

110

Comparison of circadian rhythms in male and female humans  

NASA Technical Reports Server (NTRS)

Heart rate (HR) and rectal temperature (RT) data were obtained from 12 female and 27 male subjects. The subjects were housed in a facility where the environment was controlled. Human male and female RT and HR exhibit a circadian rhythm with an excursion of about 1.2 C and 30 beats/min, respectively. The acrophases, amplitudes, and level crossings are only slightly different between the sexes. The male HR and RT circadian wave forms are more stable than those of the females. However, the actual RT and HR of males were always lower than that of females at all time points around the clock. The HR during sleep in females is 15 per cent below the daily mean heart rate and in males, 22 per cent.

Winget, C. M.; Deroshia, C. W.; Vernikos-Danellis, J.; Rosenblatt, W. S.; Hetherington, N. W.

1977-01-01

111

Respiratory Rhythm Generation In Vivo  

PubMed Central

The cellular and circuit mechanisms generating the rhythm of breathing in mammals have been under intense investigation for decades. Here, we try to integrate the key discoveries into an updated description of the basic neural processes generating respiratory rhythm under in vivo conditions. PMID:24382872

Richter, Diethelm W.; Smith, Jeffrey C.

2014-01-01

112

Circadian Rhythms in Gene Expression: Relationship to Physiology, Disease, Drug Disposition and Drug Action  

PubMed Central

Circadian rhythms (24 h cycles) are observed in virtually all aspects of mammalian function from expression of genes to complex physiological processes. The master clock is present in the suprachiasmatic nucleus (SCN) in the anterior part of the hypothalamus and controls peripheral clocks present in other parts of the body. Components of this core clock mechanism regulate the circadian rhythms in genome-wide mRNA expression, which in turn regulate various biological processes. Disruption of circadian rhythms can be either the cause or the effect of various disorders including metabolic syndrome, inflammatory diseases and cancer. Furthermore, circadian rhythms in gene expression regulate both the action and disposition of various drugs and affect therapeutic efficacy and toxicity based on dosing time. Understanding the regulation of circadian rhythms in gene expression plays an important role in both optimizing the dosing time for existing drugs and in development of new therapeutics targeting the molecular clock. PMID:20542067

Sukumaran, Siddharth; Almon, Richard R.; DuBois, Debra C.; Jusko, William J.

2010-01-01

113

Circadian rhythm sleep disorders: pathophysiology and potential approaches to management.  

PubMed

An intrinsic body clock residing in the suprachiasmatic nucleus (SCN) within the brain regulates a complex series of rhythms in humans, including sleep/wakefulness. The individual period of the endogenous clock is usually >24 hours and is normally entrained to match the environmental rhythm. Misalignment of the circadian clock with the environmental cycle may result in sleep disorders. Among these are chronic insomnias associated with an endogenous clock which runs slower or faster than the norm [delayed (DSPS) or advanced (ASPS) sleep phase syndrome, or irregular sleep-wake cycle], periodic insomnias due to disturbances in light perception (non-24-hour sleep-wake syndrome and sleep disturbances in blind individuals) and temporary insomnias due to social circumstances (jet lag and shift-work sleep disorder). Synthesis of melatonin (N-acetyl-5-methoxytryptamine) within the pineal gland is induced at night, directly regulated by the SCN. Melatonin can relay time-of-day information (signal of darkness) to various organs, including the SCN itself. The phase-shifting effects of melatonin are essentially opposite to those of light. In addition, melatonin facilitates sleep in humans. In the absence of a light-dark cycle, the timing of the circadian clock, including the timing of melatonin production in the pineal gland, may to some extent be adjusted with properly timed physical exercise. Bright light exposure has been demonstrated as an effective treatment for circadian rhythm sleep disorders. Under conditions of entrainment to the 24-hour cycle, bright light in the early morning and avoidance of light in the evening should produce a phase advance (for treatment of DSPS), whereas bright light in the evening may be effective in delaying the clock (ASPS). Melatonin, given several hours before its endogenous peak at night, effectively advances sleep time in DSPS and adjusts the sleep-wake cycle to 24 hours in blind individuals. In some blind individuals, melatonin appears to fully entrain the clock. Melatonin and light, when properly timed, may also alleviate jet lag. Because of its sleep-promoting effect, melatonin may improve sleep in night-shift workers trying to sleep during the daytime. Melatonin replacement therapy may also provide a rational approach to the treatment of age-related insomnia in the elderly. However, there is currently no melatonin formulation approved for clinical use, neither are there consensus protocols for light or melatonin therapies. The use of bright light or melatonin for circadian rhythm sleep disorders is thus considered exploratory at this stage. PMID:11463135

Zisapel, N

2001-01-01

114

Daily Novel Wheel Running Reorganizes and Splits Hamster Circadian Activity Rhythms  

Microsoft Academic Search

The phenomenon of splitting of locomotor activity rhythms in constant light has implied that the mammalian circadian pacemaker is composed of multiple interacting circadian oscillators. Exposure of male Syrian hamsters to novel running wheels also induces splitting in some reports, although novel wheel running (NWR) is better known for its effects on altering circadian phase and the length of the

Michael R. Gorman; Theresa M. Lee

2001-01-01

115

Differential Contribution of Rod and Cone Circadian Clocks in Driving Retinal Melatonin Rhythms in Xenopus  

PubMed Central

Background Although an endogenous circadian clock located in the retinal photoreceptor layer governs various physiological events including melatonin rhythms in Xenopus laevis, it remains unknown which of the photoreceptors, rod and/or cone, is responsible for the circadian regulation of melatonin release. Methodology/Principal Findings We selectively disrupted circadian clock function in either the rod or cone photoreceptor cells by generating transgenic Xenopus tadpoles expressing a dominant-negative CLOCK (XCL?Q) under the control of a rod or cone-specific promoter. Eyecup culture and continuous melatonin measurement revealed that circadian rhythms of melatonin release were abolished in a majority of the rod-specific XCL?Q transgenic tadpoles, although the percentage of arrhythmia was lower than that of transgenic tadpole eyes expressing XCL?Q in both rods and cones. In contrast, whereas a higher percentage of arrhythmia was observed in the eyes of the cone-specific XCL?Q transgenic tadpoles compare to wild-type counterparts, the rate was significantly lower than in rod-specific transgenics. The levels of the transgene expression were comparable between these two different types of transgenics. In addition, the average overall melatonin levels were not changed in the arrhythmic eyes, suggesting that CLOCK does not affect absolute levels of melatonin, only its temporal expression pattern. Conclusions/Significance These results suggest that although the Xenopus retina is made up of approximately equal numbers of rods and cones, the circadian clocks in the rod cells play a dominant role in driving circadian melatonin rhythmicity in the Xenopus retina, although some contribution of the clock in cone cells cannot be excluded. PMID:21187976

Hayasaka, Naoto; LaRue, Silvia I.; Green, Carla B.

2010-01-01

116

Serotonin 1A autoreceptor activation by S 15535 enhances circadian activity rhythms in hamsters: Evaluation of potential interactions with serotonin 2A and serotonin 2C receptors  

Microsoft Academic Search

Mammalian circadian activity rhythms are generated by pacemaker cells in the suprachiasmatic nucleus (SCN). As revealed by the actions of diverse agonists, serotonergic input from raphe nuclei generally inhibits photic signaling in the suprachiasmatic nucleus. In contrast, the serotonin (5HT)1A partial agonist, 4-(benzodioxan-5-yl)1-(indan2-yl)piperazine (S 15535), was found to enhance the phase-shifting influence of light on hamster circadian rhythms [Gannon, Neuroscience

R. L. Gannon; M. J. Millan

2006-01-01

117

Protecting the Melatonin Rhythm through Circadian Healthy Light Exposure  

PubMed Central

Currently, in developed countries, nights are excessively illuminated (light at night), whereas daytime is mainly spent indoors, and thus people are exposed to much lower light intensities than under natural conditions. In spite of the positive impact of artificial light, we pay a price for the easy access to light during the night: disorganization of our circadian system or chronodisruption (CD), including perturbations in melatonin rhythm. Epidemiological studies show that CD is associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer. Knowledge of retinal photoreceptors and the discovery of melanopsin in some ganglion cells demonstrate that light intensity, timing and spectrum must be considered to keep the biological clock properly entrained. Importantly, not all wavelengths of light are equally chronodisrupting. Blue light, which is particularly beneficial during the daytime, seems to be more disruptive at night, and induces the strongest melatonin inhibition. Nocturnal blue light exposure is currently increasing, due to the proliferation of energy-efficient lighting (LEDs) and electronic devices. Thus, the development of lighting systems that preserve the melatonin rhythm could reduce the health risks induced by chronodisruption. This review addresses the state of the art regarding the crosstalk between light and the circadian system. PMID:25526564

Bonmati-Carrion, Maria Angeles; Arguelles-Prieto, Raquel; Martinez-Madrid, Maria Jose; Reiter, Russel; Hardeland, Ruediger; Rol, Maria Angeles; Madrid, Juan Antonio

2014-01-01

118

Wavelet-based analysis of circadian behavioral rhythms.  

PubMed

The challenging problems presented by noisy biological oscillators have led to the development of a great variety of methods for accurately estimating rhythmic parameters such as period and amplitude. This chapter focuses on wavelet-based methods, which can be quite effective for assessing how rhythms change over time, particularly if time series are at least a week in length. These methods can offer alternative views to complement more traditional methods of evaluating behavioral records. The analytic wavelet transform can estimate the instantaneous period and amplitude, as well as the phase of the rhythm at each time point, while the discrete wavelet transform can extract the circadian component of activity and measure the relative strength of that circadian component compared to those in other frequency bands. Wavelet transforms do not require the removal of noise or trend, and can, in fact, be effective at removing noise and trend from oscillatory time series. The Fourier periodogram and spectrogram are reviewed, followed by descriptions of the analytic and discrete wavelet transforms. Examples illustrate application of each method and their prior use in chronobiology is surveyed. Issues such as edge effects, frequency leakage, and implications of the uncertainty principle are also addressed. PMID:25662453

Leise, Tanya L

2015-01-01

119

Protecting the melatonin rhythm through circadian healthy light exposure.  

PubMed

Currently, in developed countries, nights are excessively illuminated (light at night), whereas daytime is mainly spent indoors, and thus people are exposed to much lower light intensities than under natural conditions. In spite of the positive impact of artificial light, we pay a price for the easy access to light during the night: disorganization of our circadian system or chronodisruption (CD), including perturbations in melatonin rhythm. Epidemiological studies show that CD is associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer. Knowledge of retinal photoreceptors and the discovery of melanopsin in some ganglion cells demonstrate that light intensity, timing and spectrum must be considered to keep the biological clock properly entrained. Importantly, not all wavelengths of light are equally chronodisrupting. Blue light, which is particularly beneficial during the daytime, seems to be more disruptive at night, and induces the strongest melatonin inhibition. Nocturnal blue light exposure is currently increasing, due to the proliferation of energy-efficient lighting (LEDs) and electronic devices. Thus, the development of lighting systems that preserve the melatonin rhythm could reduce the health risks induced by chronodisruption. This review addresses the state of the art regarding the crosstalk between light and the circadian system. PMID:25526564

Bonmati-Carrion, Maria Angeles; Arguelles-Prieto, Raquel; Martinez-Madrid, Maria Jose; Reiter, Russel; Hardeland, Ruediger; Rol, Maria Angeles; Madrid, Juan Antonio

2014-01-01

120

Circadian rhythm phase shifts and endogenous free-running circadian period differ between African-Americans and European-Americans.  

PubMed

Successful adaptation to modern civilization requires the internal circadian clock to make large phase shifts in response to circumstances (e.g., jet travel and shift work) that were not encountered during most of our evolution. We found that the magnitude and direction of the circadian clock's phase shift after the light/dark and sleep/wake/meal schedule was phase-advanced (made earlier) by 9?hours differed in European-Americans compared to African-Americans. European-Americans had larger phase shifts, but were more likely to phase-delay after the 9-hour advance (to phase shift in the wrong direction). The magnitude and direction of the phase shift was related to the free-running circadian period, and European-Americans had a longer circadian period than African-Americans. Circadian period was related to the percent Sub-Saharan African and European ancestry from DNA samples. We speculate that a short circadian period was advantageous during our evolution in Africa and lengthened with northern migrations out of Africa. The differences in circadian rhythms remaining today are relevant for understanding and treating the modern circadian-rhythm-based disorders which are due to a misalignment between the internal circadian rhythms and the times for sleep, work, school and meals. PMID:25670162

Eastman, Charmane I; Suh, Christina; Tomaka, Victoria A; Crowley, Stephanie J

2015-01-01

121

Circadian rhythm phase shifts and endogenous free-running circadian period differ between African-Americans and European-Americans  

PubMed Central

Successful adaptation to modern civilization requires the internal circadian clock to make large phase shifts in response to circumstances (e.g., jet travel and shift work) that were not encountered during most of our evolution. We found that the magnitude and direction of the circadian clock's phase shift after the light/dark and sleep/wake/meal schedule was phase-advanced (made earlier) by 9?hours differed in European-Americans compared to African-Americans. European-Americans had larger phase shifts, but were more likely to phase-delay after the 9-hour advance (to phase shift in the wrong direction). The magnitude and direction of the phase shift was related to the free-running circadian period, and European-Americans had a longer circadian period than African-Americans. Circadian period was related to the percent Sub-Saharan African and European ancestry from DNA samples. We speculate that a short circadian period was advantageous during our evolution in Africa and lengthened with northern migrations out of Africa. The differences in circadian rhythms remaining today are relevant for understanding and treating the modern circadian-rhythm-based disorders which are due to a misalignment between the internal circadian rhythms and the times for sleep, work, school and meals. PMID:25670162

Eastman, Charmane I.; Suh, Christina; Tomaka, Victoria A.; Crowley, Stephanie J.

2015-01-01

122

Circadian Sleep-Wake Rhythm of Older Adults with Intellectual Disabilities  

ERIC Educational Resources Information Center

The circadian sleep-wake rhythm changes with aging, resulting in a more fragmented sleep-wake pattern. In individuals with intellectual disabilities (ID), brain structures regulating the sleep-wake rhythm might be affected. The aims of this study were to compare the sleep-wake rhythm of older adults with ID to that of older adults in the general…

Maaskant, Marijke; van de Wouw, Ellen; van Wijck, Ruud; Evenhuis, Heleen M.; Echteld, Michael A.

2013-01-01

123

Circadian rhythms. Decoupling circadian clock protein turnover from circadian period determination.  

PubMed

The mechanistic basis of eukaryotic circadian oscillators in model systems as diverse as Neurospora, Drosophila, and mammalian cells is thought to be a transcription-and-translation-based negative feedback loop, wherein progressive and controlled phosphorylation of one or more negative elements ultimately elicits their own proteasome-mediated degradation, thereby releasing negative feedback and determining circadian period length. The Neurospora crassa circadian negative element FREQUENCY (FRQ) exemplifies such proteins; it is progressively phosphorylated at more than 100 sites, and strains bearing alleles of frq with anomalous phosphorylation display abnormal stability of FRQ that is well correlated with altered periods or apparent arrhythmicity. Unexpectedly, we unveiled normal circadian oscillations that reflect the allelic state of frq but that persist in the absence of typical degradation of FRQ. This manifest uncoupling of negative element turnover from circadian period length determination is not consistent with the consensus eukaryotic circadian model. PMID:25635104

Larrondo, Luis F; Olivares-Yañez, Consuelo; Baker, Christopher L; Loros, Jennifer J; Dunlap, Jay C

2015-01-30

124

Role for LSM genes in the regulation of circadian rhythms.  

PubMed

Growing evidence suggests that core spliceosomal components differentially affect RNA processing of specific genes; however, whether changes in the levels or activities of these factors control specific signaling pathways is largely unknown. Here we show that some SM-like (LSM) genes, which encode core components of the spliceosomal U6 small nuclear ribonucleoprotein complex, regulate circadian rhythms in plants and mammals. We found that the circadian clock regulates the expression of LSM5 in Arabidopsis plants and several LSM genes in mouse suprachiasmatic nucleus. Further, mutations in LSM5 or LSM4 in Arabidopsis, or down-regulation of LSM3, LSM5, or LSM7 expression in human cells, lengthens the circadian period. Although we identified changes in the expression and alternative splicing of some core clock genes in Arabidopsis lsm5 mutants, the precise molecular mechanism causing period lengthening remains to be identified. Genome-wide expression analysis of either a weak lsm5 or a strong lsm4 mutant allele in Arabidopsis revealed larger effects on alternative splicing than on constitutive splicing. Remarkably, large splicing defects were not observed in most of the introns evaluated using RNA-seq in the strong lsm4 mutant allele used in this study. These findings support the idea that some LSM genes play both regulatory and constitutive roles in RNA processing, contributing to the fine-tuning of specific signaling pathways. PMID:25288739

Perez-Santángelo, Soledad; Mancini, Estefanía; Francey, Lauren J; Schlaen, Ruben Gustavo; Chernomoretz, Ariel; Hogenesch, John B; Yanovsky, Marcelo J

2014-10-21

125

Male courtship song in circadian rhythm mutants of Bactrocera cucurbitae (Tephritidae: Diptera).  

PubMed

Pulse train intervals (PTI) of courtship song were differentiated between circadian clock mutants of the melon fly, Bactrocera cucurbitae (Coquillett) (Tephritidae: Diptera). We analysed the male mating song of B. cucurbitae flies of two mutant strains that differed in circadian locomotor rhythm by a LabVIEW programming system. Flies with a short circadian rhythm (S-strain) had shorter PTI than those with a long circadian rhythm (L-strain) in the two age groups tested, young and old. Young flies showed longer PTI than old flies, but no interaction between strain and age was found in PTI. There was a significant interaction between strain and age for pulse train duration (PTD), whereas no stable difference was found in PTD between S- and L-strains. These results suggest a positive correlation between the length of the circadian locomotor rhythm and PTI of courtship song sounds in B. cucurbitae. PMID:15037096

Miyatake, Takahisa; Kanmiya, Kenkichi

2004-01-01

126

Alterations in circadian rhythms are associated with increased lipid peroxidation in females with bipolar disorder.  

PubMed

Disturbances in both circadian rhythms and oxidative stress systems have been implicated in the pathophysiology of bipolar disorder (BD), yet no studies have investigated the relationship between these systems in BD. We studied the impact of circadian rhythm disruption on lipid damage in 52 depressed or euthymic BD females, while controlling for age, severity of depressive symptoms and number of psychotropic medications, compared to 30 healthy controls. Circadian rhythm disruption was determined by a self-report measure (Biological Rhythm Interview of Assessment in Neuropsychiatry; BRIAN), which measures behaviours such as sleep, eating patterns, social rhythms and general activity. Malondialdehyde (MDA) levels were measured as a proxy of lipid peroxidation. We also measured the activity of total and extracellular superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST). Multiple linear regressions showed that circadian rhythm disturbance was independently associated with increased lipid peroxidation in females with BD (p < 0.05). We found decreased extracellular SOD (p < 0.05), but no differences in total SOD, CAT or GST activity between bipolar females and controls. Circadian rhythms were not associated with lipid peroxidation in healthy controls, where aging was the only significant predictor. These results suggest an interaction between the circadian system and redox metabolism, in that greater disruption in daily rhythms was associated with increased lipid peroxidation in BD only. Antioxidant enzymes have been shown to follow a circadian pattern of expression, and it is possible that disturbance of sleep and daily rhythms experienced in BD may result in decreased antioxidant defence and therefore increased lipid peroxidation. This study provides a basis for further investigation of the links between oxidative stress and circadian rhythms in the neurobiology of BD. PMID:24438530

Cudney, Lauren E; Sassi, Roberto B; Behr, Guilherme A; Streiner, David L; Minuzzi, Luciano; Moreira, Jose C F; Frey, Benicio N

2014-05-01

127

Circadian rhythms in fatty acid-induced depression of myocardial contractile function: Potential mediation by the circadian clock within the cardiomyocyte  

Technology Transfer Automated Retrieval System (TEKTRAN)

Circadian rhythms in susceptibility to cardiovascular (CV) pathologic events (e.g., arrhythmias, myocardial infarction) are well established. These phenomena have been explained largely by diurnal variations in neurohumoral influences, such as sympathetic activity. Circadian clocks are intracellular...

128

Long-term fitness training improves the circadian rest-activity rhythm in healthy elderly males.  

PubMed

In old age, the circadian timing system loses optimal functioning. This process is even accelerated in Alzheimer's disease. Because pharmacological treatment of day-night rhythm disturbances usually is not very effective and may have considerable side effects, nonpharmacological treatments deserve attention. Bright light therapy has been shown to be effective. It is known from animal studies that increased activity, or an associated process, also strongly affects the circadian timing system, and the present study addresses the question of whether an increased level of physical activity may improve circadian rhythms in elderly. In the study, 10 healthy elderly males were admitted to a fitness training program for 3 months. The circadian rest-activity rhythm was assessed by means of actigraphy before and after the training period and again 1 year after discontinuation. As a control for possible seasonal effects, repeated actigraphic recordings were performed during the same times of the year as were the pre and post measurements in a control group of 8 healthy elderly males. Fitness training induced a significant reduction in the fragmentation of the rest-activity rhythm. Moreover, the fragmentation of the rhythm was negatively correlated with the level of fitness achieved after the training. No seasonal effect was found. Previous findings in human and animal studies are reviewed, and several possible mechanisms involved in the effect of fitness training on circadian rhythms are discussed. The results suggest that fitness training may be helpful in elderly people suffering from sleep problems related to circadian rhythm disturbances. PMID:9090568

Van Someren, E J; Lijzenga, C; Mirmiran, M; Swaab, D F

1997-04-01

129

An approximation to the temporal order in endogenous circadian rhythms of genes implicated in human adipose tissue metabolism  

Technology Transfer Automated Retrieval System (TEKTRAN)

Although it is well established that human adipose tissue (AT) shows circadian rhythmicity, published studies have been discussed as if tissues or systems showed only one or few circadian rhythms at a time. To provide an overall view of the internal temporal order of circadian rhythms in human AT in...

130

Circadian rhythms persist without transcription in a eukaryote  

PubMed Central

Circadian rhythms are ubiquitous in eukaryotes, and co-ordinate numerous aspects of behaviour, physiology and metabolism, from sleep/wake cycles in mammals to growth and photosynthesis in plants1,2. This daily timekeeping is thought to be driven by transcriptional/translational feedback loops, whereby rhythmic expression of clock gene products regulates expression of associated genes in approximately 24-hour cycles. The specific transcriptional components differ between phylogenetic kingdoms3. The unicellular pico-eukaryotic alga, Ostreococcus tauri, possesses a naturally minimised clock, which includes many features that are shared with higher eukaryotes (plants), such as a central negative feedback loop that involves the morning-expressed CCA1 and evening-expressed TOC1 genes4. Given that recent observations in animals and plants have revealed prominent post-translational contributions to timekeeping5, a reappraisal of the transcriptional contribution to oscillator function is overdue. Here we show that non-transcriptional mechanisms are sufficient to sustain circadian timekeeping in the eukaryotic lineage, though they normally function in conjunction with transcriptional components. We identify oxidation of peroxiredoxin proteins as a transcription-independent rhythmic biomarker, which is also rhythmic in mammals6. Moreover we show that pharmacological modulators of the mammalian clockwork have the same effects on rhythms in Ostreococcus. Post-translational mechanisms, and at least one rhythmic marker, appear to be better conserved than transcriptional clock regulators. It is plausible that the oldest oscillator components are non-transcriptional in nature, as in cyanobacteria7, and are conserved across kingdoms. PMID:21270895

O’Neill, John S.; van Ooijen, Gerben; Dixon, Laura E.; Troein, Carl; Corellou, Florence; Bouget, François-Yves; Reddy, Akhilesh B.; Millar, Andrew J.

2010-01-01

131

Clock genes show circadian rhythms in salivary glands.  

PubMed

Circadian rhythms are endogenous self-sustained oscillations with 24-hour periods that regulate diverse physiological and metabolic processes through complex gene regulation by "clock" transcription factors. The oral cavity is bathed by saliva, and its amount and content are modified within regular daily intervals. The clock mechanisms that control salivary production remain unclear. Our objective was to evaluate the expression and periodicity of clock genes in salivary glands. Real-time quantitative RT-PCR, in situ hybridization, and immunohistochemistry were performed to show circadian mRNA and protein expression and localization of key clock genes (Bmal1, Clock, Per1, and Per2), ion and aqua channel genes (Ae2a, Car2, and Aqp5), and salivary gland markers. Clock gene mRNAs and clock proteins were found differentially expressed in the serous acini and duct cells of all major salivary glands. The expression levels of clock genes and Aqp5 showed regular oscillatory patterns under both light/dark and complete-dark conditions. Bmla1 overexpression resulted in increased Aqp5 expression levels. Analysis of our data suggests that salivary glands have a peripheral clock mechanism that functions both in normal light/dark conditions and in the absence of light. This finding may increase our understanding of the control mechanisms of salivary content and flow. PMID:22699207

Zheng, L; Seon, Y J; McHugh, J; Papagerakis, S; Papagerakis, P

2012-08-01

132

Modeling oxaliplatin drug delivery to circadian rhythms in drug metabolism and host tolerance  

E-print Network

Modeling oxaliplatin drug delivery to circadian rhythms in drug metabolism and host tolerance Jean period) time-scheduled regimens for cytotoxic drug delivery by intravenous infusion, a pharmacokinetic; Pharmacokinetics-pharmacodynamics; Treatment outcome; Chronotherapy; Drug-delivery optimization Contents 1

Clairambault, Jean

133

Circadian Rhythms in Acute Intermittent Porphyria—a Pilot Study  

PubMed Central

Acute intermittent porphyria (AIP) is an inherited disorder of heme synthesis wherein a partial deficiency of porphobilinogen [PBG] deaminase [PBGD], with other factors may give rise to biochemical and clinical manifestations of disease. The biochemical hallmarks of active AIP are relative hepatic heme deficiency and uncontrolled up-regulation of hepatic 5-aminolevulinic acid [ALA] synthase-1 [ALAS1] with overproduction of ALA and PBG. The treatment of choice is intravenous heme, which restores the deficient regulatory heme pool of the liver and represses ALAS1. Recently, heme has been shown to influence circadian rhythms by controlling their negative feedback loops. We evaluated whether subjects with AIP exhibited an altered circadian profile. Over a 21 h period, we measured levels of serum cortisol, melatonin, ALA, PBG, and mRNA levels [in peripheral blood mononuclear cells] of selected clock-controlled genes and genes involved in heme synthesis in 10 Caucasian [European-American] women who were either post-menopausal or had been receiving female hormone therapy, 6 of whom have AIP and 4 do not and are considered controls. Four AIP subjects with biochemical activity exhibited higher levels of PBG and lower levels and dampened oscillation of serum cortisol, and a trend for lower levels of serum melatonin, than controls or AIP subjects without biochemical activity. Levels of clock-controlled gene mRNAs showed significant increases over baseline in all subjects at 5 am and 11 pm, whereas mRNA levels of ALAS1, ALAS2, and PBGD were increased only at 11 pm in subjects with active AIP. This pilot study provides evidence for disturbances of circadian markers in women with active AIP that may trigger or sustain some common clinical features of AIP. PMID:23650938

Larion, Sebastian; Caballes, F. Ryan; Hwang, Sun-Il; Lee, Jin-Gyun; Rossman, Whitney Ellefson; Parsons, Judy; Steuerwald, Nury; Li, Ting; Maddukuri, Vinaya; Groseclose, Gale; Finkielstein, Carla V.; Bonkovsky, Herbert L.

2013-01-01

134

A CIRCADIAN RHYTHM IN THE LOCOMOTOR BEHAVIOUR OF THE GIANT GARDEN SLUG LIMAX MAXIMUS  

Microsoft Academic Search

SUMMARY The locomotor activity of the garden slug Limax maximus was examined for components of circadian rhythmicity. Behavioural (running wheel) studies clearly demonstrated that the activity satisfies the principal criteria of circadian rhythmicity. In constant darkness at a constant temperature, the locomotor activity freeran with a period of about 24 h (range 23-6-24-6 h). The rhythm was also expressed in

P. G. SOKOLOVE; C. M. BEISWANGER; D. J. PRIOR

135

Genetics and epigenetics of circadian rhythms and their potential roles in neuropsychiatric disorders.  

PubMed

Circadian rhythm alterations have been implicated in multiple neuropsychiatric disorders, particularly those of sleep, addiction, anxiety, and mood. Circadian rhythms are known to be maintained by a set of classic clock genes that form complex mutual and self-regulatory loops. While many other genes showing rhythmic expression have been identified by genome-wide studies, their roles in circadian regulation remain largely unknown. In attempts to directly connect circadian rhythms with neuropsychiatric disorders, genetic studies have identified gene mutations associated with several rare sleep disorders or sleep-related traits. Other than that, genetic studies of circadian genes in psychiatric disorders have had limited success. As an important mediator of environmental factors and regulators of circadian rhythms, the epigenetic system may hold the key to the etiology or pathology of psychiatric disorders, their subtypes or endophenotypes. Epigenomic regulation of the circadian system and the related changes have not been thoroughly explored in the context of neuropsychiatric disorders. We argue for systematic investigation of the circadian system, particularly epigenetic regulation, and its involvement in neuropsychiatric disorders to improve our understanding of human behavior and disease etiology. PMID:25652815

Liu, Chunyu; Chung, Michael

2015-02-01

136

Circadian-Rhythm Sleep Disorders in Persons Who Are Totally Blind.  

ERIC Educational Resources Information Center

Discusses the diagnosis and management of "non-24-hour sleep-wake syndrome," a form of cyclic insomnia to which people who are totally blind are prone. Covered are incidence and clinical features, formal diagnostic criteria, the biological basis of circadian sleep disorders, circadian rhythms in blind people, pharmacological entrainment, and the…

Sack, R. L.; Blood, M. L.; Hughes, R. J.; Lewy, A. J.

1998-01-01

137

Improved automated monitoring and new analysis algorithm for circadian phototaxis rhythms in Chlamydomonas  

PubMed Central

Automated monitoring of circadian rhythms is an efficient way of gaining insight into oscillation parameters like period and phase for the underlying pacemaker of the circadian clock. Measurement of the circadian rhythm of phototaxis (swimming towards light) exhibited by the green alga Chlamydomonas reinhardtii has been automated by directing a narrow and dim light beam through a culture at regular intervals and determining the decrease in light transmittance due to the accumulation of cells in the beam. In this study, the monitoring process was optimized by constructing a new computer-controlled measuring machine that limits the test beam to wavelengths reported to be specific for phototaxis and by choosing an algal strain, which does not need background illumination between test light cycles for proper expression of the rhythm. As a result, period and phase of the rhythm are now unaffected by the time a culture is placed into the machine. Analysis of the rhythm data was also optimized through a new algorithm, whose robustness was demonstrated using virtual rhythms with various noises. The algorithm differs in particular from other reported algorithms by maximizing the fit of the data to a sinusoidal curve that dampens exponentially. The algorithm was also used to confirm the reproducibility of rhythm monitoring by the machine. Machine and algorithm can now be used for a multitude of circadian clock studies that require unambiguous period and phase determinations such as light pulse experiments to identify the photoreceptor(s) that reset the circadian clock in C. reinhardtii. PMID:20116270

Gaskill, Christa; Forbes-Stovall, Jennifer; Kessler, Bruce; Young, Mike; Rinehart, Claire A.; Jacobshagen, Sigrid

2010-01-01

138

Bright Light Therapy Protects Women from Circadian Rhythm Desynchronization During Chemotherapy for Breast Cancer  

Microsoft Academic Search

Circadian rhythms (CRs) are commonly disrupted in women undergoing chemotherapy for breast cancer (BC). Bright light improves and strengthens CRs in other populations. This randomized controlled study examined the effect of morning administration of bright light therapy on CRs in women undergoing chemotherapy for BC. It was hypothesized that women receiving bright light therapy would exhibit more robust rhythms than

Ariel B. Neikrug; Michelle Rissling; Vera Trofimenko; Lianqi Liu; Loki Natarajan; Susan Lawton; Barbara A. Parker; Sonia Ancoli-Israel

2012-01-01

139

Bright Light Therapy Protects Women from Circadian Rhythm Desynchronization during Chemotherapy for Breast-Cancer  

Microsoft Academic Search

Purpose: Circadian rhythms (CR) are commonly disrupted in women undergoing chemotherapy for breast cancer (BC). Bright light improves and strengthens CR in other populations. This randomized controlled study examined the effect of morning administration of bright light therapy on CR in women undergoing chemotherapy for BC. We hypothesized that women receiving bright light therapy would exhibit more robust rhythms than

Ariel B. Neikrug; Michelle Rissling; Vera Trofimenko; Lianqi Liu; Loki Natarajan; Susan Lawton; Barbara A. Parker; Sonia Ancoli-Israel

2012-01-01

140

A Simple Model of Circadian Rhythms Based on Dimerization and Proteolysis of PER and TIM  

Microsoft Academic Search

Many organisms display rhythms of physiology and behavior that are entrained to the 24-h cycle of light and darkness prevailing on Earth. Under constant conditions of illumination and temperature, these internal biological rhythms persist with a period close to 1 day (“circadian”), but it is usually not exactly 24h. Recent discoveries have uncovered stunning similarities among the molecular circuitries of

John J. Tyson; Christian I. Hong; C. Dennis Thron; Bela Novak

1999-01-01

141

Effects of altitude on circadian rhythm of adult locomotor activity in Himalayan strains of Drosophila helvetica  

Microsoft Academic Search

BACKGROUND: We recently reported that the altitude of origin altered the photic and thermal sensitivity of the circadian pacemaker controlling eclosion and oviposition rhythms of high altitude Himalayan strains of Drosophila ananassae. The present study was aimed at investigating the effects of altitude of origin on the pacemaker controlling the adult locomotor activity rhythm of D. helvetica. METHODS: Locomotor activity

Keny Vanlalhriatpuia; Vanlalnghaka Chhakchhuak; Satralkar K Moses; SB Iyyer; Kasture; AJ Shivagaje; Barnabas J Rajneesh; Dilip S Joshi

2007-01-01

142

Individual variation in circadian rhythms of sleep, EEG, temperature, and activity among monkeys - Implications for regulatory mechanisms.  

NASA Technical Reports Server (NTRS)

Investigation of circadian rhythms in a number of variables related to sleep, EEG, temperature, and motor activity in rhesus monkeys on an LD 12:12 schedule. Circadian rhythms were found to appear in each of 15 variables investigated. Statistical procedures assessed the variables for evidence of common regulation in these aspects of their circadian rhythms: acrophase (timing), amplitude (extent of change), and level (24-hr mean value). Patterns appearing in the data suggested that the circadian rhythms of certain variables are regulated in common. The circadian modulation of activity in the beta and sigma frequency bands of the EEG was correlated with statistical significance in acrophase, level, and amplitude. The delta frequency band appeared to be under circadian rhythm regulation distinct from that of the other bands. The circadian rhythm of REM stage sleep was like that of beta activity in level and amplitude. The data indicate that REM stage may share some common regulation of circadian timing with both stage 3-4 sleep and with temperature. Generally, however, the circadian rhythm of temperature appeared to bear little relation to the circadian rhythms of motor activity, EEG, or sleep.

Crowley, T. J.; Halberg, F.; Kripke, D. F.; Pegram, G. V.

1971-01-01

143

Analysis of a Gene Regulatory Cascade Mediating Circadian Rhythm in Zebrafish  

PubMed Central

In the study of circadian rhythms, it has been a puzzle how a limited number of circadian clock genes can control diverse aspects of physiology. Here we investigate circadian gene expression genome-wide using larval zebrafish as a model system. We made use of a spatial gene expression atlas to investigate the expression of circadian genes in various tissues and cell types. Comparison of genome-wide circadian gene expression data between zebrafish and mouse revealed a nearly anti-phase relationship and allowed us to detect novel evolutionarily conserved circadian genes in vertebrates. We identified three groups of zebrafish genes with distinct responses to light entrainment: fast light-induced genes, slow light-induced genes, and dark-induced genes. Our computational analysis of the circadian gene regulatory network revealed several transcription factors (TFs) involved in diverse aspects of circadian physiology through transcriptional cascade. Of these, microphthalmia-associated transcription factor a (mitfa), a dark-induced TF, mediates a circadian rhythm of melanin synthesis, which may be involved in zebrafish's adaptation to daily light cycling. Our study describes a systematic method to discover previously unidentified TFs involved in circadian physiology in complex organisms. PMID:23468616

Wang, Haifang; Du, Jiulin; Yan, Jun

2013-01-01

144

Tired of diabetes genetics? Circadian rhythms and diabetes: the MTNR1B story?  

PubMed

Circadian rhythms are ubiquitous in biological systems and regulate metabolic processes throughout the body. Misalliance of these circadian rhythms and the systems they regulate has a profound impact on hormone levels and increases risk of developing metabolic diseases. Melatonin, a hormone secreted by the pineal gland, is one of the major signaling molecules used by the master circadian oscillator to entrain downstream circadian rhythms. Several recent genetic studies have pointed out that a common variant in the gene that encodes the melatonin receptor 2 (MTNR1B) is associated with impaired glucose homeostasis, reduced insulin secretion, and an increased risk of developing type 2 diabetes. Here, we try to review the role of this receptor and its signaling pathways in respect to glucose homeostasis and development of the disease. PMID:23015324

Nagorny, Cecilia; Lyssenko, Valeriya

2012-12-01

145

Circadian rhythms, multilevel models of emotion and bipolar disorder--an initial step towards integration?  

PubMed

This paper sets out possible links between disruption of circadian rhythms in bipolar disorder and the affective symptom, which are experienced in this disorder. Evidence is drawn from Healy and Williams' [Psychiatr. Dev. 1 (1989) 49.] review of circadian function in manic depression, along with later reports, which indicate a role for disrupted circadian rhythms in both depressed and manic phases of manic depression (bipolar disorder). This is integrated within a version of the multilevel model of emotion proposed by Power and Dalgleish [Cognition and emotion: from order to disorder. Hove: Psychology Press (1997); Behav. Cognit. Psychother. 27 (1999) 129.]. The aim of this process is to propose a possible psychological mechanism by which the disruption of circadian rhythms might result in the observed clinical symptoms of bipolar disorder. The integration of these approaches leads to a number of specific testable hypotheses that are relevant to future research into the psychological treatment and understanding of bipolar disorder. PMID:11702512

Jones, S H

2001-11-01

146

Actigraphic estimates of circadian rhythms and sleep/wake in older schizophrenia patients.  

PubMed

Twenty-four hour circadian activity rhythms and light-exposure levels of 28 older schizophrenia patients (mean age=58years) were examined using an Actillume recorder. Sleep and wake were scored using the algorithm of the ACTION3 software which revealed that the patients slept for 67% of the night and napped for 9% of the day. Patients with more disturbed sleep and less robust circadian rhythms performed more poorly on neuropsychological tests. Patients with higher cognitive functioning and fewer extrapyramidal symptoms were more alert during the day. Few patients were exposed to high levels of illumination during the day, and older age was associated with lower levels of light exposure. Duration of antipsychotic use and higher antipsychotic doses were associated with decreased daytime alertness and less robust circadian activity rhythms. Patients taking antipsychotics were more sleepy both during the day and night than patients not taking antipsychotics. The circadian rhythm disturbances found in these patients did not seem to be due solely to low levels of illumination exposure. Life-style factors, behavioral factors, psychiatric symptoms and medications were likely contributors to the disturbed rhythms. The effects of the sleep disturbances did not seem to be benign. There were strong relationships between sleep and circadian rhythms and functioning. PMID:11163547

Martin, J; Jeste, D V; Caliguiri, M P; Patterson, T; Heaton, R; Ancoli-Israel, S

2001-01-15

147

Bidirectional communication between sleep and circadian rhythms and its implications for depression: lessons from agomelatine.  

PubMed

Depression is a family of complex and multifactorial illnesses that are characterized by disruptions in the functioning of a number of physiological, neuroendocrine and behavioral processes. Of these, sleep disturbance and circadian rhythm abnormalities constitute the most prevalent signs of depressive illness. Difficulty in falling asleep, decreases in total sleep time and sleep efficiency, early morning awakenings, and rapid eye movement sleep alterations are all commonly seen in depressed patients. Advances or delays in the phase of circadian rhythms have been documented in patients with major depressive disorder (MDD), bipolar disorder and patients with seasonal affective disorder (SAD). The disturbances in the amplitude and rhythm of melatonin secretion that occur in patients with depression resemble those seen in subjects with chronobiological disorders. The finding that insomnia and circadian rhythm abnormalities are prominent features in depression suggests that a close link exists between melatonin secretion disturbance and depressed mood. This inference has been further strengthened by the finding that agomelatine, a recently introduced melatonergic agent with a novel mechanism of action, has beneficial effects in patients with MDD, bipolar disorder or SAD. Among agomelatine's characteristics are a rapid onset of action and a pronounced effectiveness for improving sleep efficiency and correcting circadian rhythm abnormalities. Disruptions in melatonin secretion or availability may be the common factor, which underlies depressive disorder and its prominent signs and symptoms such as sleep and circadian rhythm abnormalities. PMID:19454302

Pandi-Perumal, Seithikurippu R; Moscovitch, Adam; Srinivasan, Venkatramanujam; Spence, David Warren; Cardinali, Daniel P; Brown, Gregory M

2009-08-01

148

Estrogen receptor 1 modulates circadian rhythms in adult female mice.  

PubMed

Estradiol influences the level and distribution of daily activity, the duration of the free-running period, and the behavioral phase response to light pulses. However, the mechanisms by which estradiol regulates daily and circadian rhythms are not fully understood. We tested the hypothesis that estrogens modulate daily activity patterns via both classical and "non-classical" actions at the estrogen receptor subtype 1 (ESR1). We used female transgenic mice with mutations in their estrogen response pathways; ESR1 knock-out (ERKO) mice and "non-classical" estrogen receptor knock-in (NERKI) mice. NERKI mice have an ESR1 receptor with a mutation in the estrogen-response-element binding domain, allowing only actions via "non-classical" genomic and second messenger pathways. Ovariectomized female NERKI, ERKO, and wildtype (WT) mice were given a subcutaneous capsule with low- or high-dose estradiol and compared with counterparts with no hormone replacement. We measured wheel-running activity in a light:dark cycle and constant darkness, and the behavioral phase response to light pulses given at different points during the subjective day and night. Estradiol increased average daily wheel-running, consolidated activity to the dark phase, and shortened the endogenous period in WT, but not NERKI and ERKO mice. The timing of activity onset during entrainment was advanced in all estradiol-treated animals regardless of genotype suggesting an ESR1-independent mechanism. We propose that estradiol modifies period, activity level, and distribution of activity via classical actions of ESR1 whereas an ESR1 independent mechanism regulates the phase of rhythms. PMID:24527952

Blattner, Margaret S; Mahoney, Megan M

2014-06-01

149

Circadian intraocular pressure rhythms in athletic horses under different lighting regime.  

PubMed

The present study was undertaken to investigate the existence of intraocular pressure (IOP) rhythms in athletic thoroughbred horses maintained under a 24 h cycle of light and darkness (LD) or under constant light (LL) or constant dark (DD) conditions. We identified an IOP circadian rhythm that is entrained to the 24 h LD cycle. IOP was low during the dark phase and high during the light phase, with a peak at the end of the light phase (ZT10). The circadian rhythm of IOP persisted in DD (with a peak at CT9.5), demonstrating an endogenous component in IOP rhythm. As previously shown in other mammalian species, horse IOP circadian rhythmicity was abolished in LL. Because tonometry is performed in horses for the diagnosis of ophthalmologic diseases, such as glaucoma or anterior uveitis, the daily variation in IOP must be taken into account in clinical practice to properly time tests and to interpret clinical findings. PMID:19212846

Bertolucci, Cristiano; Giudice, Elisabetta; Fazio, Francesco; Piccione, Giuseppe

2009-02-01

150

Comparison of hormone and electrolyte circadian rhythms in male and female humans  

NASA Technical Reports Server (NTRS)

Circadian rhythm characteristics in healthy male and female humans were studied at 4-hour intervals for urine volume, cortisol, 5-hydroxyindoleacetic acid (5-HIAA), Na, K, Na/K ratios in the urine, as well as plasma cortisol. While plasma and urinary cortisol rhythms were very similar in both sexes, the described rhythms in urine volume, electrolyte, and 5-HIAA excretion differ for the two sexes. The results suggest that sex differences exist in the circadian patterns of important hormone and metabolic functions and that the internal synchrony of circadian rhythms differs for the two sexes. The results seem to indicate that the rhythmical secretion of cortisol does not account for the pattern of Na and K excretion.

Vernikos-Danellis, J.; Winget, C. M.; Goodwin, A. E.; Reilly, T.

1977-01-01

151

A Long Noncoding RNA Perturbs the Circadian Rhythm of Hepatoma Cells to Facilitate Hepatocarcinogenesis12  

PubMed Central

Clock circadian regulator (CLOCK)/brain and muscle arnt-like protein-1 (BMAL1) complex governs the regulation of circadian rhythm through triggering periodic alterations of gene expression. However, the underlying mechanism of circadian clock disruption in hepatocellular carcinoma (HCC) remains unclear. Here, we report that a long noncoding RNA (lncRNA), highly upregulated in liver cancer (HULC), contributes to the perturbations in circadian rhythm of hepatoma cells. Our observations showed that HULC was able to heighten the expression levels of CLOCK and its downstream circadian oscillators, such as period circadian clock 1 and cryptochrome circadian clock 1, in hepatoma cells. Strikingly, HULC altered the expression pattern and prolonged the periodic expression of CLOCK in hepatoma cells. Mechanistically, the complementary base pairing between HULC and the 5' untranslated region of CLOCK mRNA underlay the HULC-modulated expression of CLOCK, and the mutants in the complementary region failed to achieve the event. Moreover, immunohistochemistry staining and quantitative real-time polymerase chain reaction validated that the levels of CLOCK were elevated in HCC tissues, and the expression levels of HULC were positively associated with those of CLOCK in clinical HCC samples. In functional experiments, our data exhibited that CLOCK was implicated in the HULC-accelerated proliferation of hepatoma cells in vitro and in vivo. Taken together, our data show that an lncRNA, HULC, is responsible for the perturbations in circadian rhythm through upregulating circadian oscillator CLOCK in hepatoma cells, resulting in the promotion of hepatocarcinogenesis. Thus, our finding provides new insights into the mechanism by which lncRNA accelerates hepatocarcinogenesis through disturbing circadian rhythm of HCC. PMID:25622901

Cui, Ming; Zheng, Minying; Sun, Baodi; Wang, Yue; Ye, Lihong; Zhang, Xiaodong

2015-01-01

152

Regulation of behavioral circadian rhythms and clock protein PER1 by the deubiquitinating enzyme USP2  

PubMed Central

Summary Endogenous 24-hour rhythms are generated by circadian clocks located in most tissues. The molecular clock mechanism is based on feedback loops involving clock genes and their protein products. Post-translational modifications, including ubiquitination, are important for regulating the clock feedback mechanism. Previous work has focused on the role of ubiquitin ligases in the clock mechanism. Here we show a role for the rhythmically-expressed deubiquitinating enzyme ubiquitin specific peptidase 2 (USP2) in clock function. Mice with a deletion of the Usp2 gene (Usp2 KO) display a longer free-running period of locomotor activity rhythms and altered responses of the clock to light. This was associated with altered expression of clock genes in synchronized Usp2 KO mouse embryonic fibroblasts and increased levels of clock protein PERIOD1 (PER1). USP2 can be coimmunoprecipitated with several clock proteins but directly interacts specifically with PER1 and deubiquitinates it. Interestingly, this deubiquitination does not alter PER1 stability. Taken together, our results identify USP2 as a new core component of the clock machinery and demonstrate a role for deubiquitination in the regulation of the circadian clock, both at the level of the core pacemaker and its response to external cues. PMID:23213472

Yang, Yaoming; Duguay, David; Bédard, Nathalie; Rachalski, Adeline; Baquiran, Gerardo; Na, Chan Hyun; Fahrenkrug, Jan; Storch, Kai-Florian; Peng, Junmin; Wing, Simon S.; Cermakian, Nicolas

2012-01-01

153

Wheel-running activity modulates circadian organization and the daily rhythm of eating behavior  

PubMed Central

Consumption of high-fat diet acutely alters the daily rhythm of eating behavior and circadian organization (the phase relationship between oscillators in central and peripheral tissues) in mice. Voluntary wheel-running activity counteracts the obesogenic effects of high-fat diet and also modulates circadian rhythms in mice. In this study, we sought to determine whether voluntary wheel-running activity could prevent the proximate effects of high-fat diet consumption on circadian organization and behavioral rhythms in mice. Mice were housed with locked or freely rotating running wheels and fed chow or high-fat diet for 1 week and rhythms of locomotor activity, eating behavior, and molecular timekeeping (PERIOD2::LUCIFERASE luminescence rhythms) in ex vivo tissues were measured. Wheel-running activity delayed the phase of the liver rhythm by 4 h in both chow- and high-fat diet-fed mice. The delayed liver phase was specific to wheel-running activity since an enriched environment without the running wheel did not alter the phase of the liver rhythm. In addition, wheel-running activity modulated the effect of high-fat diet consumption on the daily rhythm of eating behavior. While high-fat diet consumption caused eating events to be more evenly dispersed across the 24 h-day in both locked-wheel and wheel-running mice, the effect of high-fat diet was much less pronounced in wheel-running mice. Together these data demonstrate that wheel-running activity is a salient factor that modulates liver phase and eating behavior rhythms in both chow- and high-fat-diet fed mice. Wheel-running activity in mice is both a source of exercise and a self-motivating, rewarding behavior. Understanding the putative reward-related mechanisms whereby wheel-running activity alters circadian rhythms could have implications for human obesity since palatable food and exercise may modulate similar reward circuits. PMID:24624109

Pendergast, Julie S.; Branecky, Katrina L.; Huang, Roya; Niswender, Kevin D.; Yamazaki, Shin

2014-01-01

154

A circadian rhythm in the locomotive behaviour of the giant garden slug Limax maximus.  

PubMed

The locomotor activity of the garden slug Limax maximus was examined for components of circadian rhythmicity. Behavioural (running wheel) studies clearly demonstrated that the activity satisfies the principal criteria of circadian rhythmicity. In constant darkness at a constant temperature, the locomotor activity freeran with a period of about 24 h (range 23-6-24-6 h). The rhythm was also expressed in constant light with a period for individual slugs that tended to be shorter in LL than in DD. The period of the rhythm was temperature compensated (11-5-21-5 degrees C) with a Q10 approximately equal to 1-00. The locomotor rhythm could be entrained to 24 h LD cycles such that the circadian activity peak occurred during the dark. The phase angle between the onset of activity and lights-off was not fixed, but was a function of the photoperiod of the entraining light cycle. PMID:858993

Sokolove, P G; Beiswanger, C M; Prior, D J; Gelperin, A

1977-02-01

155

[Circadian rhythms and temperature homeostasis in monkeys during a flight on the Kosmos 1514 biosatellite  

NASA Technical Reports Server (NTRS)

In the course of a 5-day space flight of two rhesus-monkeys the following parameters were recorded at an interval of 16 min: core body temperature (Tc), skin temperature (Ts), and motor activity (MA). The telemetric Tc sensor was implanted subcutaneously in the right axilla, Ts thermistor was attached to the right ankle, and the MA piezotape was fixed to the inner side of the vest. Circadian rhythms of Tc varied with a period of 24 hours in one monkey and 25 hours in the other. The daily Tc decreased on the average by 0.5 degrees C, Ts fell immediately after launch and remained close to the lower limit throughout the flight. The Ts amplitude decreased 5-fold. Phases of the circadian rhythms of Ts changed and circadian rhythms of MA remained unchanged and equal to 24 hours.

Klimovitskui, V. Ia; Alpatov, A. M.; Salzman, F. M.; Fuller, C. A.; Moore-Ede, M. S.

1987-01-01

156

Controlling Circadian Rhythms by Dark-Pulse Perturbations in Arabidopsis thaliana  

PubMed Central

Plant circadian systems are composed of a large number of self-sustained cellular circadian oscillators. Although the light-dark signal in the natural environment is known to be the most powerful Zeitgeber for the entrainment of cellular oscillators, its effect is too strong to control the plant rhythm into various forms of synchrony. Here, we show that the application of pulse perturbations, i.e., short-term injections of darkness under constant light, provides a novel technique for controlling the synchronized behavior of plant rhythm in Arabidopsis thaliana. By destroying the synchronized cellular activities, circadian singularity was experimentally induced. The present technique is based upon the theory of phase oscillators, which does not require prior knowledge of the detailed dynamics of the plant system but only knowledge of its phase and amplitude responses to the pulse perturbation. Our approach can be applied to diverse problems of controlling biological rhythms in living systems. PMID:23524981

Fukuda, Hirokazu; Murase, Haruhiko; Tokuda, Isao T.

2013-01-01

157

Circadian rhythms and mood: Opportunities for multi-level analyses in genomics and neuroscience  

PubMed Central

In the healthy state, both circadian rhythm and mood are stable against perturbations, yet they are capable of adjusting to altered internal cues or ongoing changes in external conditions. The dual demands of stability and flexibility are met by the collective properties of complex neural networks. Disruption of this balance underlies both circadian rhythm abnormality and mood disorders. However, we do not fully understand the network properties that govern the crosstalk between the circadian system and mood regulation. This puzzle reflects a challenge at the center of neurobiology, and its solution requires the successful integration of existing data across all levels of neural organization, from molecules, cells, circuits, network dynamics, to integrated mental function. This essay discusses several open questions confronting the cross-level synthesis, and proposes that circadian regulation, and its role in mood, stands as a uniquely tractable system to study the causal mechanisms of neural adaptation. PMID:24853393

Li, Jun Z

2014-01-01

158

Disturbed mouse circadian rhythm before the Kobe EQ in 1995  

NASA Astrophysics Data System (ADS)

Legends of macro-anomalies before large earthquakes have been passed down for generations in Asia. Most of the statements on earthquake precursors are considered unreliable afterthoughts by traditional scientists. However, disturbed biological rhythms in mice were observed before the Kobe EQ in 1995 (Yokoi et al, 2003). The records of unusual mouse behavior before the earthquake were obtained to study biological clock at Institute for Protein Research, Osaka University. It is clarified that the disturbance was very rare phenomena statistically. Similar phenomenon was observed before the Wenchuan earthquake in 2008, too (Li et al, 2009). In the presentation, I will discuss the phenomena as one example of preseismic unusual animal behaviors.

Yokoi, Sayoko

2013-04-01

159

Assaying Locomotor Activity to Study Circadian Rhythms and Sleep Parameters in Drosophila  

PubMed Central

Most life forms exhibit daily rhythms in cellular, physiological and behavioral phenomena that are driven by endogenous circadian (?24 hr) pacemakers or clocks. Malfunctions in the human circadian system are associated with numerous diseases or disorders. Much progress towards our understanding of the mechanisms underlying circadian rhythms has emerged from genetic screens whereby an easily measured behavioral rhythm is used as a read-out of clock function. Studies using Drosophila have made seminal contributions to our understanding of the cellular and biochemical bases underlying circadian rhythms. The standard circadian behavioral read-out measured in Drosophila is locomotor activity. In general, the monitoring system involves specially designed devices that can measure the locomotor movement of Drosophila. These devices are housed in environmentally controlled incubators located in a darkroom and are based on using the interruption of a beam of infrared light to record the locomotor activity of individual flies contained inside small tubes. When measured over many days, Drosophila exhibit daily cycles of activity and inactivity, a behavioral rhythm that is governed by the animal's endogenous circadian system. The overall procedure has been simplified with the advent of commercially available locomotor activity monitoring devices and the development of software programs for data analysis. We use the system from Trikinetics Inc., which is the procedure described here and is currently the most popular system used worldwide. More recently, the same monitoring devices have been used to study sleep behavior in Drosophila. Because the daily wake-sleep cycles of many flies can be measured simultaneously and only 1 to 2 weeks worth of continuous locomotor activity data is usually sufficient, this system is ideal for large-scale screens to identify Drosophila manifesting altered circadian or sleep properties. PMID:20972399

Chiu, Joanna C.; Low, Kwang Huei; Pike, Douglas H.; Yildirim, Evrim; Edery, Isaac

2010-01-01

160

Self-arrangement of cellular circadian rhythms through phase-resetting in plant roots  

NASA Astrophysics Data System (ADS)

We discovered a striped pattern of gene expression with circadian rhythms in growing plant roots using bioluminescent imaging of gene expression. Our experimental analysis revealed that the stripe wave in the bioluminescent image originated at the root tip and was caused by a continuous phase resetting of circadian oscillations. Some complex stripe waves containing arrhythmic regions were also observed. We succeeded in describing the formation mechanisms of these patterns using a growing phase oscillator network with a phase-resetting boundary condition.

Fukuda, Hirokazu; Ukai, Kazuya; Oyama, Tokitaka

2012-10-01

161

Seasonal effects on the freerunning rhythm of circadian activity of longnose dace ( Rhinichthys cataractae )  

Microsoft Academic Search

Synopsis Freerunning circadian rhythms of locomotor activity in individual longnose dace sampled from a population at 41°N latitude were recorded under constant darkness throughout the year. There was an annual cycle in the length of the circadian period, with maximum and minimum lengths of mean period of 23.6 and 21.6 h recorded during summer (June) and winter (December), respectively. These

Martin Kavaliers

1981-01-01

162

Regulation of Drosophila circadian rhythms by miRNA let-7 is mediated by a regulatory cycle.  

PubMed

MicroRNA-mediated post-transcriptional regulations are increasingly recognized as important components of the circadian rhythm. Here we identify microRNA let-7, part of the Drosophila let-7-Complex, as a regulator of circadian rhythms mediated by a circadian regulatory cycle. Overexpression of let-7 in clock neurons lengthens circadian period and its deletion attenuates the morning activity peak as well as molecular oscillation. Let-7 regulates the circadian rhythm via repression of CLOCKWORK ORANGE (CWO). Conversely, upregulated cwo in cwo-expressing cells can rescue the phenotype of let-7-Complex overexpression. Moreover, circadian prothoracicotropic hormone (PTTH) and CLOCK-regulated 20-OH ecdysteroid signalling contribute to the circadian expression of let-7 through the 20-OH ecdysteroid receptor. Thus, we find a regulatory cycle involving PTTH, a direct target of CLOCK, and PTTH-driven miRNA let-7. PMID:25417916

Chen, Wenfeng; Liu, Zhenxing; Li, Tianjiao; Zhang, Ruifeng; Xue, Yongbo; Zhong, Yang; Bai, Weiwei; Zhou, Dasen; Zhao, Zhangwu

2014-01-01

163

Circadian Rhythm Hypotheses of Mixed Features, Antidepressant Treatment Resistance, and Manic Switching in Bipolar Disorder  

PubMed Central

Numerous hypotheses have been put forth over the years to explain the development of bipolar disorder. Of these, circadian rhythm hypotheses have gained much importance of late. While the hypothalamus-pituitary-adrenal (HPA) axis hyperactivation hypothesis and the monoamine hypothesis somewhat explain the pathogenic mechanism of depression, they do not provide an explanation for the development of mania/hypomania. Interestingly, all patients with bipolar disorder display significant disruption of circadian rhythms and sleep/wake cycles throughout their mood cycles. Indeed, mice carrying the Clock gene mutation exhibit an overall behavioral profile that is similar to human mania, including hyperactivity, decreased sleep, lowered depression-like behavior, and lower anxiety. It was recently reported that monoamine signaling is in fact regulated by the circadian system. Thus, circadian rhythm instability, imposed on the dysregulation of HPA axis and monoamine system, may in turn increase individual susceptibility for switching from depression to mania/hypomania. In addition to addressing the pathophysiologic mechanism underlying the manic switch, circadian rhythm hypotheses can explain other bipolar disorder-related phenomena such as treatment resistant depression and mixed features. PMID:24302944

Son, Gi-Hoon; Geum, Dongho

2013-01-01

164

Smooth-muscle BMAL1 participates in blood pressure circadian rhythm regulation.  

PubMed

As the central pacemaker, the suprachiasmatic nucleus (SCN) has long been considered the primary regulator of blood pressure circadian rhythm; however, this dogma has been challenged by the discovery that each of the clock genes present in the SCN is also expressed and functions in peripheral tissues. The involvement and contribution of these peripheral clock genes in the circadian rhythm of blood pressure remains uncertain. Here, we demonstrate that selective deletion of the circadian clock transcriptional activator aryl hydrocarbon receptor nuclear translocator-like (Bmal1) from smooth muscle, but not from cardiomyocytes, compromised blood pressure circadian rhythm and decreased blood pressure without affecting SCN-controlled locomotor activity in murine models. In mesenteric arteries, BMAL1 bound to the promoter of and activated the transcription of Rho-kinase 2 (Rock2), and Bmal1 deletion abolished the time-of-day variations in response to agonist-induced vasoconstriction, myosin phosphorylation, and ROCK2 activation. Together, these data indicate that peripheral inputs contribute to the daily control of vasoconstriction and blood pressure and suggest that clock gene expression outside of the SCN should be further evaluated to elucidate pathogenic mechanisms of diseases involving blood pressure circadian rhythm disruption. PMID:25485682

Xie, Zhongwen; Su, Wen; Liu, Shu; Zhao, Guogang; Esser, Karyn; Schroder, Elizabeth A; Lefta, Mellani; Stauss, Harald M; Guo, Zhenheng; Gong, Ming Cui

2014-12-01

165

Circadian Rhythms of Crawling and Swimming in the Nudibranch Mollusc Melibe leonina.  

PubMed

Daily rhythms of activity driven by circadian clocks are expressed by many organisms, including molluscs. We initiated this study, with the nudibranch Melibe leonina, with four goals in mind: (1) determine which behaviors are expressed with a daily rhythm; (2) investigate which of these rhythmic behaviors are controlled by a circadian clock; (3) determine if a circadian clock is associated with the eyes or optic ganglia of Melibe, as it is in several other gastropods; and (4) test the hypothesis that Melibe can use extraocular photoreceptors to synchronize its daily rhythms to natural light-dark cycles. To address these goals, we analyzed the behavior of 55 animals exposed to either artificial or natural light-dark cycles, followed by constant darkness. We also repeated this experiment using 10 animals that had their eyes removed. Individuals did not express daily rhythms of feeding, but they swam and crawled more at night. This pattern of locomotion persisted in constant darkness, indicating the presence of a circadian clock. Eyeless animals also expressed a daily rhythm of locomotion, with more locomotion at night. The fact that eyeless animals synchronized their locomotion to the light-dark cycle suggests that they can detect light using extraocular photoreceptors. However, in constant darkness, these rhythms deteriorated, suggesting that the clock neurons that influence locomotion may be located in, or near, the eyes. Thus, locomotion in Melibe appears to be influenced by both ocular and extraocular photoreceptors, although the former appear to have a greater influence on the expression of circadian rhythms. PMID:25572214

Newcomb, James M; Kirouac, Lauren E; Naimie, Amanda A; Bixby, Kimberly A; Lee, Colin; Malanga, Stephanie; Raubach, Maureen; Watson, Winsor H

2014-12-01

166

Circadian rhythm of leaf movement in Capsicum annuum observed during centrifugation  

NASA Technical Reports Server (NTRS)

Plant circadian rhythms of leaf movement in seedlings of the pepper plant (Capsicum annuum L., var. Yolo Wonder) were observed at different g-levels by means of a centrifuge. Except for the chronically imposed g-force all environmental conditions to which the plants were exposed were held constant. The circadian period, rate of change of amplitude of successive oscillations, symmetry of the cycles, and phase of the rhythm all were found not to be significantly correlated with the magnitude of the sustained g-force.

Chapman, D. K.; Brown, A. H.; Dahl, A. O.

1975-01-01

167

Circadian rhythms in Neurospora crassa on a polydimethylsiloxane microfluidic device for real-time gas perturbations  

PubMed Central

Racetubes, a conventional system employing hollow glass tubes, are typically used for monitoring circadian rhythms from the model filamentous fungus, Neurospora crassa. However, a major technical limitation in using a conventional system is that racetubes are not amenable for real-time gas perturbations. In this work, we demonstrate a simple microfluidic device combined with real-time gas perturbations for monitoring circadian rhythms in Neurospora crassa using bioluminescence assays. The developed platform is a useful toolbox for investigating molecular responses under various gas conditions for Neurospora and can also be applied to other microorganisms. PMID:24404062

Lee, Kang Kug; Ahn, Chong H.; Hong, Christian I.

2013-01-01

168

Role of p53 in the entrainment of mammalian circadian behavior rhythms.  

PubMed

p53 protein plays a role for control of cell proliferation and the induction of apoptosis in normal cells. However, its role in the circadian rhythms that control many physiological functions including locomotor behavior remains unknown. The present study examined the locomotors activity rhythms of mice which have homozygous mutations of p53 gene. The period of drinking activity rhythms in p53 knockout (p53 KO) mice became unstable under constant dark. Light pulse causes a big phase shifts at CT15.5-17, when p53 mRNA expression peaks in the suprachiasmatic nucleus (SCN). Furthermore, photic entrainment of p53 KO mice is unusual under light-dark conditions. These findings suggest that p53 is involved in entrainment of the circadian behavioral rhythm. PMID:24698115

Hamada, Toshiyuki; Niki, Tomoko; Ishida, Norio

2014-05-01

169

No time to lose: workshop on circadian rhythms and metabolic disease  

PubMed Central

The objective of the workshop was to gain a better understanding of the link between circadian rhythms and human health and disease. The impacts of circadian rhythms on metabolic gene regulation, as well as the effect of nutrient uptake and balance on the molecular components of the clock, were discussed. Topics included the neural circuitry underlying the central clock; the effect of the environment and diet on the central clock as well as peripheral, tissue-specific clocks; and the transcriptional, post-transcriptional, and post-translational (e.g., epigenomic) mechanisms through which these signals are transduced. Evidence presented during the meeting demonstrated that circadian rhythms and metabolism are intricately linked, and that disruption in these rhythms have profound consequences—many times leading to metabolic disease. The mechanisms by which circadian rhythms are maintained and the cross-talk with metabolic signaling are just beginning to be elucidated. However, the interactions between these fields and the knowledge learned will clearly have a profound impact on our understanding of metabolic disease and lead to novel therapeutic approaches in the future PMID:20634312

Silva, Corinne M.; Sato, Sheryl; Margolis, Ronald N.

2010-01-01

170

Comparison of synchronization of primate circadian rhythms by light and food  

NASA Technical Reports Server (NTRS)

It is a well-documented fact that cycles of light and dark (LD) are the major entraining agent or 'zeitgeber' for circadian rhythms and that cycles of eating and fasting (EF) are capable of synchronizing a few circadian rhythms in the squirrel monkey. In this paper, by contrasting how these rhythms are timed by LD and EF cycles, the differential coupling to the oscillating system within adult male squirrel monkeys is examined. The variables measured are the rhythms of drinking, colonic temperature, and urinary potassium and water excretion. Attention is given to a comparison of the reproducibility of the averaged waveforms of the rhythms, the stability of the timing of a phase reference point, and the rate of resynchronization of these rhythms following an abrupt 8-hr phase delay in the zeitgeber. It is shown that the colonic temperature rhythm is more tightly controlled by LD than EF cycles, and that the drinking and urinary rhythms are more tightly coupled to EF than LD cycles.

Sulzman, F. M.; Fuller, C. A.; Moore-Ede, M. C.

1978-01-01

171

Circadian Rhythm Disorders and Melatonin Production in 127 Blind Women with and without Light Perception.  

PubMed

Light is the major environmental time cue that synchronizes the endogenous central circadian pacemaker, located in the suprachiasmatic nuclei of the hypothalamus, and is detected exclusively by the eyes primarily via specialized non-rod, non-cone ganglion cell photoreceptors. Consequently, most blind people with no perception of light (NPL) have either nonentrained or abnormally phased circadian rhythms due to this inability to detect light. Conversely, most visually impaired participants with some degree of light perception (LP) exhibit normal entrainment, emphasizing the functional separation of visual and "nonvisual" photoreception. The aims of the study were to identify the prevalence of circadian disorders in blind women, with the further aim of examining how eye disease may relate to the type of circadian disorder. Participants (n = 127, age 50.8 ± 13.4 years) completed an 8-week field study including daily sleep diaries and sequential 4 to 8 hourly urine collections over 48 h on 2 to 3 occasions separated by at least 2 weeks. Circadian type was determined from the timing and time course of the melatonin rhythm measured by cosinor-derived urinary 6-sulfatoxymelatonin rhythm peak. Of the participants with NPL (n = 41), the majority were abnormally phased (24%) or nonentrained (39%), with 37% classified as normally entrained. Of the participants with LP (n = 86), the majority were normally entrained (69%). Eighteen LP participants (21%) were abnormally phased (8 advanced, 10 delayed). Nine LP participants (10%) were nonentrained. The eye conditions most associated with abnormal phase and/or nonentrained circadian rhythms were bilateral enucleation (67%) and retinopathy of prematurity (57%). By contrast, 84% of participants with retinitis pigmentosa and 83% of those with age-related macular degeneration were normally entrained. These findings suggest that the etiology of blindness in addition to LP status is related to an individual's ability to process the circadian light signal. PMID:24916394

Flynn-Evans, Erin E; Tabandeh, Homayoun; Skene, Debra J; Lockley, Steven W

2014-06-10

172

Circadian Rhythm of Nitrogenase Gene Expression in the Diazotrophic Filamentous Nonheterocystous Cyanobacterium Trichodesmium sp. Strain IMS 101  

Microsoft Academic Search

Recent studies suggested that the daily cycle of nitrogen fixation activity in the marine filamentous nonhet- erocystous cyanobacterium Trichodesmium sp. is controlled by a circadian rhythm. In this study, we evaluated the rhythm of nitrogen fixation in Trichodesmium sp. strain IMS 101 by using the three criteria for an endogenous rhythm. Nitrogenase transcript abundance oscillated with a period of approximately

YI-BU CHEN; BENNY DOMINIC; MARK T. MELLON; JONATHAN P. ZEHR

1998-01-01

173

Effect of feeding regimens on circadian rhythms: Implications for aging and longevity  

PubMed Central

Increased longevity and improved health can be achieved in mammals by two feeding regimens, caloric restriction (CR), which limits the amount of daily calorie intake, and intermittent fasting (IF), which allows the food to be availablead libitum every other day. The precise mechanisms mediating these beneficial effects are still unresolved. Resetting the circadian clock is another intervention that can lead to increased life span and well being, while clock disruption is associated with aging and morbidity. Currently, a large body of evidence links circadian rhythms with metabolism and feeding regimens. In particular, CR, and possibly also IF, can entrain the master clock located in the suprachiasmatic nuclei (SCN) of the brain hypothalamus. These findings raise the hypothesis that the beneficial effects exerted by these feeding regimens could be mediated, at least in part, through resetting of the circadian clock, thus leading to synchrony in metabolism and physiology. This hypothesis is reinforced by a transgenic mouse model showing spontaneously reduced eating alongside robust circadian rhythms and increased life span. This review will summarize recent findings concerning the relationships between feeding regimens, circadian rhythms, and metabolism with implications for ageing attenuation and life span extension. PMID:20228939

Froy, Oren; Miskin, Ruth

2010-01-01

174

Circadian Rhythms and Mood Regulation: Insights from Pre-Clinical Models  

PubMed Central

Affective disorders such as major depression, bipolar disorder, and seasonal affective disorder are associated with major disruptions in circadian rhythms. Indeed, altered sleep/wake cycles are a critical feature for diagnosis in the DSM IV and several of the therapies used to treat these disorders have profound effects on rhythm length and stabilization in human populations. Furthermore, multiple human genetic studies have identified polymorphisms in specific circadian genes that associate with these disorders. Thus, there appears to be a strong association between the circadian system and mood regulation, although the mechanisms that underlie this association are unclear. Recently, a number of studies in animal models have begun to shed light on the complex interactions between circadian genes and mood-related neurotransmitter systems, the effects of light manipulation on brain circuitry, the impact of chronic stress on rhythms, and the ways in which antidepressant and mood-stabilizing drugs alter the clock. This review will focus on the recent advances that have been gleaned from the use of pre-clinical models to further our understanding of how the circadian system regulates mood. PMID:21835596

McClung, Colleen A.

2011-01-01

175

Circadian rhythms and mood regulation: insights from pre-clinical models.  

PubMed

Affective disorders such as major depression, bipolar disorder, and seasonal affective disorder are associated with major disruptions in circadian rhythms. Indeed, altered sleep/wake cycles are a critical feature for diagnosis in the DSM IV and several of the therapies used to treat these disorders have profound effects on rhythm length and stabilization in human populations. Furthermore, multiple human genetic studies have identified polymorphisms in specific circadian genes associated with these disorders. Thus, there appears to be a strong association between the circadian system and mood regulation, although the mechanisms that underlie this association are unclear. Recently, a number of studies in animal models have begun to shed light on the complex interactions between circadian genes and mood-related neurotransmitter systems, the effects of light manipulation on brain circuitry, the impact of chronic stress on rhythms, and the ways in which antidepressant and mood-stabilizing drugs alter the clock. This review will focus on the recent advances that have been gleaned from the use of pre-clinical models to further our understanding of how the circadian system regulates mood. PMID:21835596

McClung, Colleen A

2011-09-01

176

Dementia severity and Lewy bodies affect circadian rhythms in Alzheimer disease  

Microsoft Academic Search

Sleep disturbance is a symptom shared by all neurodegenerative, dementing illnesses, such as Alzheimer’s disease (AD) and dementia with Lewy bodies (DLB), and its presence frequently precipitates decisions to seek institutional care for patients. Although the sleep disturbances of AD and DLB are qualitatively similar, they appear to be more prominent in patients with DLB. Disturbance of the circadian rhythm

David G. Harper; Edward G. Stopa; Ann C. McKee; Andrew Satlin; David Fish; Ladislav Volicer

2004-01-01

177

The Suprachiasmatic Nucleus Is Essential for Circadian Body Temperature Rhythms in Hibernating Ground Squirrels  

E-print Network

The Suprachiasmatic Nucleus Is Essential for Circadian Body Temperature Rhythms in Hibernating in constant light, suggest that light can reach the retina of hibernating ground squirrels maintained in the laboratory and affect hibernation via an SCN-independent mechanism. Key words: suprachiasmatic nucleus

Zucker, Irving

178

Seasonal Variations in Circadian Rhythms of Deer Mice, in Northwestern Canada  

Microsoft Academic Search

Circadian rhythms of Peromyscus maniculatus were studied at Heart Lake, Northwest Territories, in winter and spring of 1965-1966. Daily peaks of activity were of longer duration and higher amplitude in spring than in winter. In winter deer mice were frequently observed in torpor and most activity occurred at night. In spring daily peaks of activity began before dark and extended

179

CIRCADIAN RHYTHMS OF FEEDING, OVIPOSITION, AND EMERGENCE OF THE BOLL WEEVIL (COLEOPTERA: CURCULIONIDAE)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Circadian rhythm of feeding, oviposition, and emergence of boll weevil adults were determined at 5 different photophases (24, 14, 12, 10 and 0 hours) and a constant 27 deg C temperature, 65% RH in the laboratory. Squares from petri dishes, where they were exposed to boll weevil females, were remove...

180

Long-Term Fitness Training Improves the Circadian Rest-Activity Rhythm in Healthy Elderly Males  

Microsoft Academic Search

In old age, the circadian timing system loses optimal functioning. This process is even accelerated in Alzheimer's disease. Because pharmacological treatment of day-night rhythm disturbances usually is not very effective and may have considerable side effects, nonpharmacological treatments deserve attention. Bright light therapy has been shown to be effective. It is known from animal studies that increased activity, or an

Eus J. W. Van Someren; Cees Lijzenga; Majid Mirmiran; Dick F. Swaab

1997-01-01

181

Free-running circadian activity rhythms in free-living beaver ( Castor canadensis )  

Microsoft Academic Search

The members of a beaver family studied under natural conditions in SW Alberta, Canada (115 °03' W, 51 °02' N) displayed a free-running circadian rhythm of activity with a period length of about 27 hours in winter, at a time when they were living under ice and had no access to land (Fig. 1, A and C). In summer, the

Jacques Bovet; Erwin F. Oertli

1974-01-01

182

CIRCADIAN RHYTHMS IN PLANTS: MA-CHINE LEARNING MODELS AND BIOIN-  

E-print Network

AND BIOIN- FORMATICS APPROACHES Daniel Trejo Banos, Institute for Adaptive and Neural Compu- tation, School of Informatics Supervisors: Guido Sanguinetti, Andrew J. Millar and Christo- pher M. Bishop d.trejo-banos@sms.ed.ac.uk http://www.inf.ed.ac.uk/people/students/Daniel_Trejo_Banos.html Introduction Circadian Rhythms

Chaudhuri, Surajit

183

Effects of pinealectomy on circadian locomotor activity rhythms in european starlings, Sturnus vulgaris  

Microsoft Academic Search

Removal of the pineal organ from starlings had drastic effects on their freerunning circadian activity rhythms; in birds kept in continuous darkness the period (t) shortened and the activity time (a) lengthened. Concomitantly botht anda became relatively unstable and the separation between activity and rest time was obscured. In a few birds activity became continuous and apparently arrhythmic. The activity

Eberhard Gwinner

1978-01-01

184

Pulses of darkness shift the phase of a circadian rhythm in an insectivorous bat  

Microsoft Academic Search

Summary The circadian rhythm of a tropical insectivorous bat,Taphozous melanopogon, free-runs in dim light and responds to dark breaks of a few hours' duration with ‘advances’ and ‘delays’ as a function of the phase experiencing the “black out”. Similarly phase shifts also follow perturbations by light breaks. The time course and the wave form of the phase response curves obtained

Ramanujam Subbaraj; Maroli K. Chandrashekaran

1978-01-01

185

Darwin, Earthworms & Circadian Rhythms: A Fertile Field for Science Fair Experiments  

ERIC Educational Resources Information Center

This article discusses why the study of earthworms has fascinated many scientists, and why earthworms make ideal experimental animals for students to test in the laboratory. Although earthworms may appear to be primitive, they are governed by both circadian and seasonal rhythms, just as more advanced organisms are. They possess an intelligence…

Burns, John T.; Scurti, Paul J.; Furda, Amy M.

2009-01-01

186

A Comparative Study of Circadian Rhythm Functioning and Sleep in People with Asperger Syndrome  

ERIC Educational Resources Information Center

The circadian rhythm functioning and sleep patterns of 10 adults with Asperger syndrome were investigated using actigraphy. When compared with data from neurotypical adults, both statistical and clinically significant differences were found between the two groups, with the adults with Asperger syndrome showing marked abnormalities in both the…

Hare, Dougal Julian; Jones, Steven; Evershed, Kate

2006-01-01

187

Relationships between circadian rhythms and modulation of gene expression by glucocorticoids in skeletal muscle  

PubMed Central

The existence and maintenance of biological rhythms linked to the 24-h light-dark cycle are essential to the health and functioning of an organism. Although much is known concerning central clock mechanisms, much less is known about control in peripheral tissues. In this study, circadian regulation of gene expression was examined in rat skeletal muscle. A rich time series involving 54 animals euthanized at 18 distinct time points within the 24-h cycle was performed, and mRNA expression in gastrocnemius muscles was examined using Affymetrix gene arrays. Data mining identified 109 genes that were expressed rhythmically, which could be grouped into eight distinct temporal clusters within the 24-h cycle. These genes were placed into 11 functional categories, which were examined within the context of temporal expression. Transcription factors involved in the regulation of central rhythms were examined, and eight were found to be rhythmically expressed in muscle. Because endogenous glucocorticoids are a major effector of circadian rhythms, genes identified here were compared with those identified in previous studies as glucocorticoid regulated. Of the 109 genes identified here as circadian rhythm regulated, only 55 were also glucocorticoid regulated. Examination of transcription factors involved in circadian control suggests that corticosterone may be the initiator of their rhythmic expression patterns in skeletal muscle. PMID:18667713

Almon, Richard R.; Yang, Eric; Lai, William; Androulakis, Ioannis P.; Ghimbovschi, Svetlana; Hoffman, Eric P.; Jusko, William J.; DuBois, Debra C.

2008-01-01

188

Circadian Clocks in Antennal Neurons Are Necessary and Sufficient for Olfaction Rhythms in Drosophila  

Microsoft Academic Search

Background: The Drosophila circadian clock is controlled by interlocked transcriptional feedback loops that operate in many neuronal and nonneuronal tissues. These clocks are roughly divided into a central clock, which resides in the brain and is known to control rhythms in locomotor activity, and peripheral clocks, which comprise all other clock tissues and are thought to control other rhythmic outputs.

Shintaro Tanoue; Parthasarathy Krishnan; Balaji Krishnan; Stuart E Dryer; Paul E Hardin

2004-01-01

189

Practice Parameters for the Clinical Evaluation and Treatment of Circadian Rhythm Sleep Disorders  

PubMed Central

The expanding science of circadian rhythm biology and a growing literature in human clinical research on circadian rhythm sleep disorders (CRSDs) prompted the American Academy of Sleep Medicine (AASM) to convene a task force of experts to write a review of this important topic. Due to the extensive nature of the disorders covered, the review was written in two sections. The first review paper, in addition to providing a general introduction to circadian biology, addresses “exogenous” circadian rhythm sleep disorders, including shift work disorder (SWD) and jet lag disorder (JLD). The second review paper addresses the “endogenous” circadian rhythm sleep disorders, including advanced sleep phase disorder (ASPD), delayed sleep phase disorder (DSPD), irregular sleep-wake rhythm (ISWR), and the non–24-hour sleep-wake syndrome (nonentrained type) or free-running disorder (FRD). These practice parameters were developed by the Standards of Practice Committee and reviewed and approved by the Board of Directors of the AASM to present recommendations for the assessment and treatment of CRSDs based on the two accompanying comprehensive reviews. The main diagnostic tools considered include sleep logs, actigraphy, the Morningness-Eveningness Questionnaire (MEQ), circadian phase markers, and polysomnography. Use of a sleep log or diary is indicated in the assessment of patients with a suspected circadian rhythm sleep disorder (Guideline). Actigraphy is indicated to assist in evaluation of patients suspected of circadian rhythm disorders (strength of recommendation varies from “Option” to “Guideline,” depending on the suspected CRSD). Polysomnography is not routinely indicated for the diagnosis of CRSDs, but may be indicated to rule out another primary sleep disorder (Standard). There is insufficient evidence to justify the use of MEQ for the routine clinical evaluation of CRSDs (Option). Circadian phase markers are useful to determine circadian phase and confirm the diagnosis of FRD in sighted and unsighted patients but there is insufficient evidence to recommend their routine use in the diagnosis of SWD, JLD, ASPD, DSPD, or ISWR (Option). Additionally, actigraphy is useful as an outcome measure in evaluating the response to treatment for CRSDs (Guideline). A range of therapeutic interventions were considered including planned sleep schedules, timed light exposure, timed melatonin doses, hypnotics, stimulants, and alerting agents. Planned or prescribed sleep schedules are indicated in SWD (Standard) and in JLD, DSPD, ASPD, ISWR (excluding elderly-demented/nursing home residents), and FRD (Option). Specifically dosed and timed light exposure is indicated for each of the circadian disorders with variable success (Option). Timed melatonin administration is indicated for JLD (Standard); SWD, DSPD, and FRD in unsighted persons (Guideline); and for ASPD, FRD in sighted individuals, and for ISWR in children with moderate to severe psychomotor retardation (Option). Hypnotic medications may be indicated to promote or improve daytime sleep among night shift workers (Guideline) and to treat jet lag-induced insomnia (Option). Stimulants may be indicated to improve alertness in JLD and SWD (Option) but may have risks that must be weighed prior to use. Modafinil may be indicated to improve alertness during the night shift for patients with SWD (Guideline). Citation: Morgenthaler TI; Lee-Chiong T; Alessi C; Friedman L; Aurora N; Boehlecke B; Brown T; Chesson AL; Kapur V; Maganti R; Owens J; Pancer J; Swick TJ; Zak R; Standards of Practice Committee of the AASM. Practice Parameters for the Clinical Evaluation and Treatment of Circadian Rhythm Sleep Disorders. SLEEP 2007;30(11):1445-1459. PMID:18041479

Morgenthaler, Timothy I.; Lee-Chiong, Teofilo; Alessi, Cathy; Friedman, Leah; Aurora, R. Nisha; Boehlecke, Brian; Brown, Terry; Chesson, Andrew L.; Kapur, Vishesh; Maganti, Rama; Owens, Judith; Pancer, Jeffrey; Swick, Todd J.; Zak, Rochelle

2007-01-01

190

Long and short isoforms of Neurospora clock protein FRQ support temperature compensated circadian rhythms  

PubMed Central

The large (l) and small (s) isoforms of FREQUENCY (FRQ) are elements of interconnected feedback loops of the Neurospora circadian clock. The expression ratio of l-FRQ versus s-FRQ is regulated by thermosensitive splicing of an intron containing the initiation codon for l-FRQ. We show that this splicing is dependent on light and temperature and displays a circadian rhythm. Strains expressing only l-FRQ or s-FRQ support short and long temperature-compensated circadian rhythms, respectively. The thermosensitive expression ratio of FRQ isoforms influences period length in wt. Our data indicate that differential expression of FRQ isoforms is not required for temperature compensation but rather provides a means to fine-tune period length in response to ambient temperature. PMID:18037381

Diernfellner, Axel; Colot, Hildur V.; Dintsis, Orfeas; Loros, Jennifer J.; Dunlap, Jay C.; Brunner, Michael

2009-01-01

191

Circadian Mechanisms of Food Anticipatory Rhythms in Rats Fed Once or Twice Daily: Clock Gene and Endocrine Correlates  

PubMed Central

Circadian clocks in many brain regions and peripheral tissues are entrained by the daily rhythm of food intake. Clocks in one or more of these locations generate a daily rhythm of locomotor activity that anticipates a regular mealtime. Rats and mice can also anticipate two daily meals. Whether this involves 1 or 2 circadian clocks is unknown. To gain insight into how the circadian system adjusts to 2 daily mealtimes, male rats in a 12?12 light-dark cycle were fed a 2 h meal either 4 h after lights-on or 4 h after lights-off, or a 1 h meal at both times. After 30 days, brain, blood, adrenal and stomach tissue were collected at 6 time points. Multiple clock genes from adrenals and stomachs were assayed by RT-PCR. Blood was assayed for corticosterone and ghrelin. Bmal1 expression was quantified in 14 brain regions by in situ hybridization. Clock gene rhythms in adrenal and stomach from day-fed rats oscillated in antiphase with the rhythms in night-fed rats, and at an intermediate phase in rats fed twice daily. Corticosterone and ghrelin in 1-meal rats peaked at or prior to the expected mealtime. In 2-meal rats, corticosterone peaked only prior the nighttime meal, while ghrelin peaked prior to the daytime meal and then remained elevated. The olfactory bulb, nucleus accumbens, dorsal striatum, cerebellum and arcuate nucleus exhibited significant daily rhythms of Bmal1 in the night-fed groups that were approximately in antiphase in the day-fed groups, and at intermediate levels (arrhythmic) in rats anticipating 2 daily meals. The dissociations between anticipatory activity and the peripheral clocks and hormones in rats anticipating 2 daily meals argue against a role for these signals in the timing of behavioral rhythms. The absence of rhythmicity at the tissue level in brain regions from rats anticipating 2 daily meals support behavioral evidence that circadian clock cells in these tissues may reorganize into two populations coupled to different meals. PMID:25502949

Patton, Danica F.; Katsuyama, Ângela M.; Pavlovski, Ilya; Michalik, Mateusz; Patterson, Zachary; Parfyonov, Maksim; Smit, Andrea N.; Marchant, Elliott G.; Chung, John; Abizaid, Alfonso; Storch, Kai-Florian; de la Iglesia, Horacio; Mistlberger, Ralph E.

2014-01-01

192

Drosophila TRPA1 functions in temperature control of circadian rhythm in pacemaker neurons  

PubMed Central

Most animals from flies to humans count on circadian clocks to synchronize their physiology and behaviors. Daily light cycles are well-known environmental cues for setting circadian rhythms. Warmer and cooler temperatures that mimic day and night are also effective in entraining circadian activity in most animals. Even vertebrate organisms can be induced to show circadian responses through exposure to temperature cycles. In poikilothermic animals such as Drosophila, temperature differences of only 2–3°C are sufficient to synchronize locomotor rhythms. However, the molecular sensors that participate in temperature regulation of circadian activity in fruit flies or other animals are enigmatic. It is also unclear whether such detectors are limited to the periphery or may be in the central brain. Here, we showed that Drosophila TRPA1 (Transient Receptor Potential Cation Channel A1) was necessary for normal activity patterns during temperature cycles. The trpA1 gene was expressed in a subset of pacemaker neurons in the central brain. In response to temperature entrainment, loss of trpA1 impaired activity, and altered expression of the circadian clock protein Period (Per) in a subset of pacemaker neurons. These findings underscore a role for a thermoTRP in temperature regulation that extends beyond avoidance of noxious or suboptimal temperatures. PMID:23595730

Lee, Youngseok; Montell, Craig

2013-01-01

193

Light pulses entrain the circadian activity rhythm of a diurnal rodent (Ammospermophilus leucurus).  

PubMed

Circadian rhythms of wheel-running activity of the antelope ground squirrel (Ammospermophilus leucurus) were entrained by light-dark cycles (LD: 100 1x vs total darkness) with periods (T) between ca 23.75 and 24.75 hr. Two 1-hr light pulses per cycle ('skeleton photoperiods') with T = 24.25 hr as well as one 1-hr light pulse per cycle with Ts of 23.75 and 24.25 hr were effective in entraining the circadian activity rhythms in at least 50% of the antelope ground squirrels. Phase and period responses to single 1-hr light pulses were measured which depend on the initial phase and period of the rhythm. It is concluded that discrete (phasic) light input contributes to the mechanism of entrainment to LD cycles in diurnal rodents. PMID:6661897

Pohl, H

1983-01-01

194

Alteration of Daily and Circadian Rhythms following Dopamine Depletion in MPTP Treated Non-Human Primates  

PubMed Central

Disturbances of the daily sleep/wake cycle are common non-motor symptoms of Parkinson's disease (PD). However, the impact of dopamine (DA) depletion on circadian rhythms in PD patients or non-human primate (NHP) models of the disorder have not been investigated. We evaluated alterations of circadian rhythms in NHP following MPTP lesion of the dopaminergic nigro-striatal system. DA degeneration was assessed by in vivo PET ([11C]-PE2I) and post-mortem TH and DAT quantification. In a light?dark cycle, control and MPTP-treated NHP both exhibit rest-wake locomotor rhythms, although DA-depleted NHP show reduced amplitude, decreased stability and increased fragmentation. In all animals, 6-sulphatoxymelatonin peaks at night and cortisol in early morning. When the circadian system is challenged by exposure to constant light, controls retain locomotor rest-wake and hormonal rhythms that free-run with stable phase relationships whereas in the DA-depleted NHP, locomotor rhythms are severely disturbed or completely abolished. The amplitude and phase relations of hormonal rhythms nevertheless remain unaltered. Use of a light-dark masking paradigm shows that expression of daily rest-wake activity in MPTP monkeys requires the stimulatory and inhibitory effects of light and darkness. These results suggest that following DA lesion, the central clock in the SCN remains intact but, in the absence of environmental timing cues, is unable to drive downstream rhythmic processes of striatal clock gene and dopaminergic functions that control locomotor output. These findings suggest that the circadian component of the sleep-wake disturbances in PD is more profoundly affected than previously assumed. PMID:24465981

Fifel, Karim; Vezoli, Julien; Dzahini, Kwamivi; Claustrat, Bruno; Leviel, Vincent; Kennedy, Henry; Procyk, Emmanuel; Dkhissi-Benyahya, Ouria; Gronfier, Claude; Cooper, Howard M.

2014-01-01

195

Circadian rhythm and profile in patients with juvenile myoclonic epilepsy and temporal lobe epilepsy.  

PubMed

Objective This study intended to compare the circadian rhythm and circadian profile between patients with juvenile myoclonic epilepsy (JME) and patients with temporal lobe epilepsy (TLE). Method We enrolled 16 patients with JME and 37 patients with TLE from the Outpatient Clinic of UNICAMP. We applied a questionnaire about sleep-wake cycle and circadian profile. Results Fourteen (87%) out of 16 patients with JME, and 22 out of 37 (59%) patients with TLE reported that they would sleep after seizure (p < 0.05). Three (19%) patients with JME, and 17 (46%) reported to be in better state before 10:00 AM (p < 0.05). Conclusion There is no clear distinct profile and circadian pattern in patients with JME in comparison to TLE patients. However, our data suggest that most JME patients do not feel in better shape early in the day. PMID:25608119

Fukuda, Aya; Funari, Mateus P; Fernandes, Paula T; Guerreiro, Carlos Mantovani; Li, Li Min

2015-01-01

196

The Nuclear Receptor Genes HR3 and E75 Are Required for the Circadian Rhythm in a Primitive Insect  

PubMed Central

Insect circadian rhythms are generated by a circadian clock consisting of transcriptional/translational feedback loops, in which CYCLE and CLOCK are the key elements in activating the transcription of various clock genes such as timeless (tim) and period (per). Although the transcriptional regulation of Clock (Clk) has been profoundly studied, little is known about the regulation of cycle (cyc). Here, we identify the orphan nuclear receptor genes HR3 and E75, which are orthologs of mammalian clock genes, Ror? and Rev-erb?, respectively, as factors involved in the rhythmic expression of the cyc gene in a primitive insect, the firebrat Thermobia domestica. Our results show that HR3 and E75 are rhythmically expressed, and their normal, rhythmic expression is required for the persistence of locomotor rhythms. Their RNAi considerably altered the rhythmic transcription of not only cyc but also tim. Surprisingly, the RNAi of HR3 revealed the rhythmic expression of Clk, suggesting that this ancestral insect species possesses the mechanisms for rhythmic expression of both cyc and Clk genes. When either HR3 or E75 was knocked down, tim, cyc, and Clk or tim and cyc, respectively, oscillated in phase, suggesting that the two genes play an important role in the regulation of the phase relationship among the clock genes. Interestingly, HR3 and E75 were also found to be involved in the regulation of ecdysis, suggesting that they interconnect the circadian clock and developmental processes. PMID:25502221

Kamae, Yuichi; Uryu, Outa; Miki, Taiki; Tomioka, Kenji

2014-01-01

197

Circadian rhythms of visual accommodation responses and physiological correlations.  

NASA Technical Reports Server (NTRS)

Use of a recently developed servocontrolled infrared optometer to continuously record the state of monocular focus while subjects viewed a visual target for which the stimulus to focus was systematically varied. Calculated parameters form recorded data - e.g., speeds of accommodation to approaching and receding targets, magnitude of accommodation to step changes in target distance, and amplitude and phase lag of response to sinusoidally varying stimuli were submitted to periodicity analyses. Ear canal temperature (ECT) and heart rate (HR) rhythms were also recorded for physiological correlation with accommodation rhythms. HR demonstrated a 24-hr rhythm, but ECT data did not.

Murphy, M. R.; Randle, R. J.; Williams, B. A.

1972-01-01

198

Animal activity around the clock with no overt circadian rhythms: patterns, mechanisms and adaptive value.  

PubMed

Circadian rhythms are ubiquitous in many organisms. Animals that are forced to be active around the clock typically show reduced performance, health and survival. Nevertheless, we review evidence of animals showing prolonged intervals of activity with attenuated or nil overt circadian rhythms and no apparent ill effects. We show that around-the-clock and ultradian activity patterns are more common than is generally appreciated, particularly in herbivores, in animals inhabiting polar regions and habitats with constant physical environments, in animals during specific life-history stages (such as migration or reproduction), and in highly social animals. The underlying mechanisms are diverse, but studies suggest that some circadian pacemakers continue to measure time in animals active around the clock. The prevalence of around-the-clock activity in diverse animals and habitats, and an apparent diversity of underlying mechanisms, are consistent with convergent evolution. We suggest that the basic organizational principles of the circadian system and its complexity encompass the potential for chronobiological plasticity. There may be trade-offs between benefits of persistent daily rhythms versus plasticity, which for reasons still poorly understood make overt daily arrhythmicity functionally adaptive only in selected habitats and for selected lifestyles. PMID:23825202

Bloch, Guy; Barnes, Brian M; Gerkema, Menno P; Helm, Barbara

2013-08-22

199

Circadian rhythms in electric waveform structure and rate in the electric fish Brachyhypopomus pinnicaudatus  

PubMed Central

Weakly electric fish have long been known to express day–night oscillations in their discharge rates, and in the amplitude and duration of individual electric organ discharges (EODs). Because these oscillations are altered by social environment and neuroendocrine interactions, electric fish are excellent organisms for exploring the social and neuroendocrine regulation of circadian rhythm expression. Previous studies asserting that these oscillations are circadian rhythms have been criticized for failing to control temperature and randomize feeding regimes, or for running the fish under constant conditions for just 2–3 days. Here we show that the day–night oscillations in the EODs of the neotropical gymnotiform fish Brachyhypopomus pinnicaudatus free-run for over a week under constant photic and thermal conditions, and randomized food provisioning. Sex differences were apparent in strength and magnitude of the circadian oscillations; male oscillations were stronger and larger. All three parameters retain a common oscillation period while differing in the persistence of oscillation strength and magnitude, a difference consistent with proposals by others that declines of behavioral circadian rhythms may result from breakdowns downstream of the central oscillator. PMID:16996093

Stoddard, Philip K.; Markham, Michael R.; Salazar, Vielka L.; Allee, Susan

2008-01-01

200

Animal activity around the clock with no overt circadian rhythms: patterns, mechanisms and adaptive value  

PubMed Central

Circadian rhythms are ubiquitous in many organisms. Animals that are forced to be active around the clock typically show reduced performance, health and survival. Nevertheless, we review evidence of animals showing prolonged intervals of activity with attenuated or nil overt circadian rhythms and no apparent ill effects. We show that around-the-clock and ultradian activity patterns are more common than is generally appreciated, particularly in herbivores, in animals inhabiting polar regions and habitats with constant physical environments, in animals during specific life-history stages (such as migration or reproduction), and in highly social animals. The underlying mechanisms are diverse, but studies suggest that some circadian pacemakers continue to measure time in animals active around the clock. The prevalence of around-the-clock activity in diverse animals and habitats, and an apparent diversity of underlying mechanisms, are consistent with convergent evolution. We suggest that the basic organizational principles of the circadian system and its complexity encompass the potential for chronobiological plasticity. There may be trade-offs between benefits of persistent daily rhythms versus plasticity, which for reasons still poorly understood make overt daily arrhythmicity functionally adaptive only in selected habitats and for selected lifestyles. PMID:23825202

Bloch, Guy; Barnes, Brian M.; Gerkema, Menno P.; Helm, Barbara

2013-01-01

201

Sleep, performance, circadian rhythms, and light-dark cycles during two space shuttle flights  

NASA Technical Reports Server (NTRS)

Sleep, circadian rhythm, and neurobehavioral performance measures were obtained in five astronauts before, during, and after 16-day or 10-day space missions. In space, scheduled rest-activity cycles were 20-35 min shorter than 24 h. Light-dark cycles were highly variable on the flight deck, and daytime illuminances in other compartments of the spacecraft were very low (5.0-79.4 lx). In space, the amplitude of the body temperature rhythm was reduced and the circadian rhythm of urinary cortisol appeared misaligned relative to the imposed non-24-h sleep-wake schedule. Neurobehavioral performance decrements were observed. Sleep duration, assessed by questionnaires and actigraphy, was only approximately 6.5 h/day. Subjective sleep quality diminished. Polysomnography revealed more wakefulness and less slow-wave sleep during the final third of sleep episodes. Administration of melatonin (0.3 mg) on alternate nights did not improve sleep. After return to earth, rapid eye movement (REM) sleep was markedly increased. Crewmembers on these flights experienced circadian rhythm disturbances, sleep loss, decrements in neurobehavioral performance, and postflight changes in REM sleep.

Dijk, D. J.; Neri, D. F.; Wyatt, J. K.; Ronda, J. M.; Riel, E.; Ritz-De Cecco, A.; Hughes, R. J.; Elliott, A. R.; Prisk, G. K.; West, J. B.; Czeisler, C. A.

2001-01-01

202

Circadian rhythms in the cell cycle and biomass composition of Neochloris oleoabundans under nitrogen limitation.  

PubMed

The circadian clock schedules processes in microalgae cells at suitable times in the day/night cycle. To gain knowledge about these biological time schedules, Neochloris oleoabundans was grown under constant light conditions and nitrogen limitation. Under these constant conditions, the only variable was the circadian clock. The results were compared to previous work done under nitrogen-replete conditions, in order to determine the effect of N-limitation on circadian rhythms in the cell cycle and biomass composition of N. oleoabundans. The circadian clock was not affected by nitrogen-limitation, and cell division was timed in the natural night, despite of constant light conditions. However, because of nitrogen-limitation, not the entire population was able to divide every day. Two subpopulations were observed, which divided alternately every other day. This caused oscillations in biomass yield and composition. Starch and total fatty acids (TFA) were accumulated during the day. Also, fatty acid composition changed during the cell cycle. Neutral lipids were built up during the day, especially in cells that were arrested in their cell cycle (G2 and G3). These findings give insight in the influence of circadian rhythms on the cell cycle and biomass composition. PMID:25062660

de Winter, Lenneke; Schepers, Lutz W; Cuaresma, Maria; Barbosa, Maria J; Martens, Dirk E; Wijffels, René H

2014-10-10

203

Long-Lasting Effects of Sepsis on Circadian Rhythms in the Mouse  

PubMed Central

Daily patterns of activity and physiology are termed circadian rhythms and are driven primarily by an endogenous biological timekeeping system, with the master clock located in the suprachiasmatic nucleus. Previous studies have indicated reciprocal relationships between the circadian and the immune systems, although to date there have been only limited explorations of the long-term modulation of the circadian system by immune challenge, and it is to this question that we addressed ourselves in the current study. Sepsis was induced by peripheral treatment with lipopolysaccharide (5 mg/kg) and circadian rhythms were monitored following recovery. The basic parameters of circadian rhythmicity (free-running period and rhythm amplitude, entrainment to a light/dark cycle) were unaltered in post-septic animals compared to controls. Animals previously treated with LPS showed accelerated re-entrainment to a 6 hour advance of the light/dark cycle, and showed larger phase advances induced by photic stimulation in the late night phase. Photic induction of the immediate early genes c-FOS, EGR-1 and ARC was not altered, and neither was phase-shifting in response to treatment with the 5-HT-1a/7 agonist 8-OH-DPAT. Circadian expression of the clock gene product PER2 was altered in the suprachiasmatic nucleus of post-septic animals, and PER1 and PER2 expression patterns were altered also in the hippocampus. Examination of the suprachiasmatic nucleus 3 months after treatment with LPS showed persistent upregulation of the microglial markers CD-11b and F4/80, but no changes in the expression of various neuropeptides, cytokines, and intracellular signallers. The effects of sepsis on circadian rhythms does not seem to be driven by cell death, as 24 hours after LPS treatment there was no evidence for apoptosis in the suprachiasmatic nucleus as judged by TUNEL and cleaved-caspase 3 staining. Overall these data provide novel insight into how septic shock exerts chronic effects on the mammalian circadian system. PMID:23071720

O'Callaghan, Emma K.; Anderson, Sean T.; Moynagh, Paul N.; Coogan, Andrew N.

2012-01-01

204

Circadian Rhythms in Cognitive Processes: Implications for School Learning  

ERIC Educational Resources Information Center

Circadian variations have been found in cognitive processes, such as attention, working memory, and executive functions, which may explain oscillations in the performance of many tasks. These cognitive processes improve during the day and decrease during the night and early hours of the morning. Sleep deprivation further decreases these cognitive…

Valdez, Pablo; Ramírez, Candelaria; García, Aída

2014-01-01

205

Dopamine and circadian rhythms in seasonal affective disorder  

Microsoft Academic Search

In seasonal affective disorder, there is evidence of both increased and decreased dopaminergic transmission in the central nervous system. Bright light treatment appears to normalize these abnormalities among the patients. Dopamine is suggested to have a direct effect on heat loss via the vascular system, in addition to its capability of resetting the circadian system by changes in both heat

T. Partonen

1996-01-01

206

Free-running circadian rhythms of muscle strength, reaction time, and body temperature in totally blind people.  

PubMed

Light is the major synchronizer of circadian rhythms. In the absence of light, as for totally blind people, some variables, such as body temperature, have an endogenous period that is longer than 24 h and tend to be free running. However, the circadian rhythm of muscle strength and reaction time in totally blind people has not been defined in the literature. The objective of this study was to determine the period of the endogenous circadian rhythm of the isometric and isokinetic contraction strength and simple reaction time of totally blind people. The study included six totally blind people with free-running circadian rhythms and four sighted people (control group). Although the control group required only a single session to determine the circadian rhythm, the blind people required three sessions to determine the endogenous period. In each session, isometric strength, isokinetic strength, reaction time, and body temperature were collected six different times a day with an interval of at least 8 h. The control group had better performance for strength and reaction time in the afternoon. For the blind, this performance became delayed throughout the day. Therefore, we conclude that the circadian rhythms of strength and simple reaction time of totally blind people are within their free-running periods. For some professionals, like the blind paralympic athletes, activities that require large physiological capacities in which the maximum stimulus should match the ideal time of competition may result in the blind athletes falling short of their expected performance under this free-running condition. PMID:22618303

Squarcini, Camila Fabiana Rossi; Pires, Maria Laura Nogueira; Lopes, Cleide; Benedito-Silva, Ana Amélia; Esteves, Andrea Maculano; Cornelissen-Guillaume, Germaine; Matarazzo, Carolina; Garcia, Danilo; da Silva, Maria Stella Peccin; Tufik, Sergio; de Mello, Marco Túlio

2013-01-01

207

Circadian locomotor activity rhythms of the burbot, Lota lota : Seasonal differences in period length and the effect of pinealectomy  

Microsoft Academic Search

The burbot,Lota lota, displayed a freerunning circadian locomotor activity rhythm under constant darkness. There was a seasonal change in the length of the circadian period (t). Fish captured during winter had a meant of 21.2±0.30 h as opposed to at of 23.5±0.25 in summer. Removal of the pineal organ had significant effects on the length and stability of the circadian

Martin Kavaliers

1980-01-01

208

A statistical model of the human core-temperature circadian rhythm  

NASA Technical Reports Server (NTRS)

We formulate a statistical model of the human core-temperature circadian rhythm in which the circadian signal is modeled as a van der Pol oscillator, the thermoregulatory response is represented as a first-order autoregressive process, and the evoked effect of activity is modeled with a function specific for each circadian protocol. The new model directly links differential equation-based simulation models and harmonic regression analysis methods and permits statistical analysis of both static and dynamical properties of the circadian pacemaker from experimental data. We estimate the model parameters by using numerically efficient maximum likelihood algorithms and analyze human core-temperature data from forced desynchrony, free-run, and constant-routine protocols. By representing explicitly the dynamical effects of ambient light input to the human circadian pacemaker, the new model can estimate with high precision the correct intrinsic period of this oscillator ( approximately 24 h) from both free-run and forced desynchrony studies. Although the van der Pol model approximates well the dynamical features of the circadian pacemaker, the optimal dynamical model of the human biological clock may have a harmonic structure different from that of the van der Pol oscillator.

Brown, E. N.; Choe, Y.; Luithardt, H.; Czeisler, C. A.

2000-01-01

209

Impact of behavior on central and peripheral circadian clocks in the common vole Microtus arvalis, a mammal with ultradian rhythms  

PubMed Central

In most mammals, daily rhythms in physiology are driven by a circadian timing system composed of a master pacemaker in the suprachiasmatic nucleus (SCN) and peripheral oscillators in most body cells. The SCN clock, which is phase-entrained by light–dark cycles, is thought to synchronize subsidiary oscillators in peripheral tissues, mainly by driving cyclic feeding behavior. Here, we examined the expression of circadian clock genes in the SCN and the liver of the common vole Microtus arvalis, a rodent with ultradian activity and feeding rhythms. In these animals, clock-gene mRNAs accumulate with high circadian amplitudes in the SCN but are present at nearly constant levels in the liver. Interestingly, high-amplitude circadian liver gene expression can be elicited by subjecting voles to a circadian feeding regimen. Moreover, voles with access to a running wheel display a composite pattern of circadian and ultradian behavior, which correlates with low-amplitude circadian gene expression in the liver. Our data indicate that, in M. arvalis, the amplitude of circadian liver gene expression depends on the contribution of circadian and ultradian components in activity and feeding rhythms. PMID:16481616

van der Veen, Daan R.; Minh, Nguyet Le; Gos, Pascal; Arneric, Milica; Gerkema, Menno P.; Schibler, Ueli

2006-01-01

210

Cortisol Circadian Rhythms and Stress Responses in Infants at Risk of Allergic Disease  

Microsoft Academic Search

Altered hypothalamic-pituitary-adrenal function associated with allergic disease has generally been thought to be secondary to the stress of chronic disease. However, recent studies suggest that altered cortisol circadian rhythm and cortisol stress hyper-responsiveness precede the inception of allergic disease and are possible links between preventive factors associated with the hygiene hypothesis and the development of allergies. Elevated endogenous cortisol responses

Thomas M. Ball

2006-01-01

211

The Downs and Ups of Mechanistic Research: Circadian Rhythm Research as an Exemplar  

Microsoft Academic Search

In the context of mechanistic explanation, reductionistic research pursues a decomposition of complex systems into their component\\u000a parts and operations. Using research on the mechanisms responsible for circadian rhythms, I consider both the gains that have\\u000a been made by discovering genes and proteins that figure in these intracellular oscillators and also highlight the increasingly\\u000a recognized need to understand higher-level integration,

William Bechtel

2010-01-01

212

Milking frequency affects the circadian body temperature rhythm in dairy cows  

Microsoft Academic Search

The objective of this study was to investigate milking frequency as a potential stressor in Holstein–Friesian dairy cows managed in a pastoral farming system. The circadian body (vaginal) temperature rhythm was measured in cows milked twice-a-day (2x) or once-a-day (1x) in two experiments. The first experiment was conducted at peak lactation (50±11 days in milk, DIM) and the second in response

P. E. Kendall; C. B. Tucker; D. E. Dalley; D. A. Clark; J. R. Webster

2008-01-01

213

Effects of microgravity on circadian rhythms in insects  

NASA Technical Reports Server (NTRS)

The desert beetle Trigonoscelis gigas Reitt. was used as a biological model in studies that examined the effects of space flight on the circadian timing system. Results from studies aboard the Bion-10, Bion-11, and Photon-11 missions are reported. The control study is an ongoing Mir experiment. The studies indicate that the free-running period in beetles may be longer during space flight.

Alpatov, A. M.; Hoban-Higgins, T. M.; Fuller, C. A.; Lazarev, A. O.; Rietveld, W. J.; Tschernyshev, V. B.; Tumurova, E. G.; Wassmer, G.; Zotov, V. A.

1998-01-01

214

Lipids around the Clock: Focus on Circadian Rhythms and Lipid Metabolism.  

PubMed

Disorders of lipid and lipoprotein metabolism and transport are responsible for the development of a large spectrum of pathologies, ranging from cardiovascular diseases, to metabolic syndrome, even to tumour development. Recently, a deeper knowledge of the molecular mechanisms that control our biological clock and circadian rhythms has been achieved. From these studies it has clearly emerged how the molecular clock tightly regulates every aspect of our lives, including our metabolism. This review analyses the organisation and functioning of the circadian clock and its relevance in the regulation of physiological processes. We also describe metabolism and transport of lipids and lipoproteins as an essential aspect for our health, and we will focus on how the circadian clock and lipid metabolism are greatly interconnected. Finally, we discuss how a deeper knowledge of this relationship might be useful to improve the recent spread of metabolic diseases. PMID:25665169

Gnocchi, Davide; Pedrelli, Matteo; Hurt-Camejo, Eva; Parini, Paolo

2015-01-01

215

Sleep and circadian rhythms in long duration space flight - Antarctica as an analogue environment  

NASA Technical Reports Server (NTRS)

The feasibility of using Antarctica as an environment for studying the impact of unusual 24 h environmental cycles (zeitgebers) on the circadian system is discussed. Adaptation of circadian rhythms and sleep of three scientists travelling from New Zealand to Antarctica during summer (which is analogous to arrival at a lunar base during the lunar day) has been studied. Data obtained indicate that sleep occurred at the same clock time, but sleep quality was poorer in Antarctica, which can be explained by the fact that the circadian system delayed by about 2 h in Antarctica, as would be expected in a weaker zeitgeber environment. It is suggested that sleep could be improved by altering patterns of exposure to the available zeitgebers to increase their effective strength.

Gander, Philippa H.

1992-01-01

216

Cognitive Performance as a Zeitgeber: Cognitive Oscillators and Cholinergic Modulation of the SCN Entrain Circadian Rhythms  

PubMed Central

The suprachiasmatic nucleus (SCN) is the primary circadian pacemaker in mammals that can synchronize or entrain to environmental cues. Although light exerts powerful influences on SCN output, other non-photic stimuli can modulate the SCN as well. We recently demonstrated that daily performance of a cognitive task requiring sustained periods of attentional effort that relies upon basal forebrain (BF) cholinergic activity dramatically alters circadian rhythms in rats. In particular, normally nocturnal rats adopt a robust diurnal activity pattern that persists for several days in the absence of cognitive training. Although anatomical and pharmacological data from non-performing animals support a relationship between cholinergic signaling and circadian rhythms, little is known about how endogenous cholinergic signaling influences SCN function in behaving animals. Here we report that BF cholinergic projections to the SCN provide the principal signal allowing for the expression of cognitive entrainment in light-phase trained animals. We also reveal that oscillator(s) outside of the SCN drive cognitive entrainment as daily timed cognitive training robustly entrains SCN-lesioned arrhythmic animals. Ablation of the SCN, however, resulted in significant impairments in task acquisition, indicating that SCN-mediated timekeeping benefits new learning and cognitive performance. Taken together, we conclude that cognition entrains non-photic oscillators, and cholinergic signaling to the SCN serves as a temporal timestamp attenuating SCN photic-driven rhythms, thereby permitting cognitive demands to modulate behavior. PMID:23441168

Gritton, Howard J.; Stasiak, Ashley M.; Sarter, Martin; Lee, Theresa M.

2013-01-01

217

Circadian rhythms differ between sexes and closely related species of Nasonia wasps.  

PubMed

Activity rhythms in 24 h light-dark cycles, constant darkness, and constant light conditions were analyzed in four different Nasonia species for each sex separately. Besides similarities, clear differences are evident among and within Nasonia species as well as between sexes. In all species, activity in a light-dark cycle is concentrated in the photophase, typical for diurnal organisms. Contrary to most diurnal insect species so far studied, Nasonia follows Aschoff's rule by displaying long (>24 h) internal rhythms in constant darkness but short (<24 h) in constant light. In constant light, N. vitripennis males display robust circadian activity rhythms, whereas females are usually arrhythmic. In contrast to other Nasonia species, N. longicornis males display anticipatory activity, i.e. activity shortly before light-on in a light-dark cycle. As expected, N. oneida shows activity patterns similar to those of N. giraulti but with important differences in key circadian parameters. Differences in circadian activity patterns and parameters between species may reflect synchronization of specific life-history traits to environmental conditions. Scheduling mating or dispersion to a specific time of the day could be a strategy to avoid interspecific hybridization in Nasonia species that live in sympatry. PMID:23555911

Bertossa, Rinaldo C; van Dijk, Jeroen; Diao, Wenwen; Saunders, David; Beukeboom, Leo W; Beersma, Domien G M

2013-01-01

218

Circadian Rhythms Differ between Sexes and Closely Related Species of Nasonia Wasps  

PubMed Central

Activity rhythms in 24 h light-dark cycles, constant darkness, and constant light conditions were analyzed in four different Nasonia species for each sex separately. Besides similarities, clear differences are evident among and within Nasonia species as well as between sexes. In all species, activity in a light-dark cycle is concentrated in the photophase, typical for diurnal organisms. Contrary to most diurnal insect species so far studied, Nasonia follows Aschoff's rule by displaying long (>24 h) internal rhythms in constant darkness but short (<24 h) in constant light. In constant light, N. vitripennis males display robust circadian activity rhythms, whereas females are usually arrhythmic. In contrast to other Nasonia species, N. longicornis males display anticipatory activity, i.e. activity shortly before light-on in a light-dark cycle. As expected, N. oneida shows activity patterns similar to those of N. giraulti but with important differences in key circadian parameters. Differences in circadian activity patterns and parameters between species may reflect synchronization of specific life-history traits to environmental conditions. Scheduling mating or dispersion to a specific time of the day could be a strategy to avoid interspecific hybridization in Nasonia species that live in sympatry. PMID:23555911

Bertossa, Rinaldo C.; van Dijk, Jeroen; Diao, Wenwen; Saunders, David; Beukeboom, Leo W.; Beersma, Domien G. M.

2013-01-01

219

Dissociation of body-temperature and melatonin secretion circadian rhythms in patients with chronic fatigue syndrome.  

PubMed

Many patients with chronic fatigue syndrome (CFS) display features of hypothalamic dysfunction. We have investigated aspects of circadian rhythmicity, an important hypothalamic function, in 20 CFS patients and in 17 age- and sex-matched healthy control subjects. There were no differences between the two groups in the amplitude, mesor (mean value) or timing of the peak (acrophase) of the circadian rhythm of core temperature, or in the timing of the onset of melatonin secretion. However, the CFS patients showed no significant correlation between the timing of the temperature acrophase and the melatonin onset (P < 0.5), whereas the normal significant correlation was observed in the controls (P < 0.05). Dissociation of circadian rhythms could be due to the sleep deprivation and social disruption, and/or the reduction in physical activity which typically accompany CFS. By analogy with jet-lag and shift-working, circadian dysrhythmia could be an important factor in initiating and perpetuating the cardinal symptoms of CFS, notably tiredness, impaired concentration and intellectual impairment. PMID:8842569

Williams, G; Pirmohamed, J; Minors, D; Waterhouse, J; Buchan, I; Arendt, J; Edwards, R H

1996-07-01

220

Light as a central modulator of circadian rhythms, sleep and affect  

PubMed Central

Light has profoundly influenced the evolution of life on earth. As widely appreciated, light allows us to generate images of our environment. However, light, through the atypical intrinsically photosensitive retinal ganglion cells (ipRGCs; Box 1), also influences behaviors that are essential for our health and quality of life, yet are independent of image formation. These include the synchronization of the circadian clock to the solar day, tracking of seasonal changes, and regulation of sleep. Irregular light environments lead to problems in circadian rhythms and sleep, which eventually cause mood and learning deficits. Recently, it was found that irregular light can also directly impact mood and learning without producing major disruptions in circadian rhythms and sleep. Here, we will discuss the indirect and direct influence of light on mood and learning and provide a model for how light, the circadian clock, and sleep interact to influence mood and cognitive functions. Box 1Intrinsically photosensitive retinal ganglion cells (ipRGCs)Retinal photoreceptors transduce light energy into electrical signals that initiate vision. The classical photoreceptors, rods and cones, possess modified cilia that consist of stacks of membranes in which photopigments (rhodopsin and cone opsins) are concentrated. Rods are exquisitely sensitive and are able to detect even a few photons. Rods are therefore used for night vision. Cones are less sensitive than rods and are used for day and color vision. Color vision is mediated by cone photoreceptors that express cone-opsins with sensitivity peaks at different wavelengths (colors) of light. Humans have three cone types: short, mid and long wavelength sensitive cones (for simplicity, we will refer to these as blue, green and red cones, respectively). Rods and cones relay photic information through multisynaptic pathways to retinal ganglion cells (RGCs), which innervate different areas in the brain for complex visual processing13.A surprising discovery showed that a subpopulation of RGCs is intrinsically photosensitive and express the photopigment melanopsin. These cells were thus termed ipRGCs17–19. The melanopsin gene (Opn4) was originally cloned from Xenopus laevis dermal melanophores, and was shown to have orthologs in many mammalian species, including humans141. Sequence analysis shows that melanopsin shares more homology with invertebrate opsins than with vertebrate opsins, suggesting that melanopsin may use a different mechanism for light signaling than that used by the photopigments present in the rods and cones of vertebrates142. ipRGCs do not have modified membranes in which the photopigment can be concentrated: thus, melanopsin protein is expressed uniformly throughout the soma, dendrites, and the initial segment of the axon143. The lack of membrane specialization makes ipRGCs less sensitive to light than rods and cones. However, ipRGCs are able to incorporate light signals over extended period of time, resulting in an increase in their sensitivity during prolonged light stimulation. ipRGCs are most sensitive to wavelengths of light that are in the blue region of the light spectrum144, 145. As ganglion cells, ipRGCs also convey light information from rods and cones in addition to their intrinsic melanopsin-dependent pathway and can control a variety of light-mediated behaviors30.Originally, ipRGCs were thought to comprise a uniform population, however, recent discoveries revealed that ipRGCs are highly diverse, comprising at least five distinct subtypes (M1-M5) in rodents based on morphological and electrophysiological analyses22–29. The originally identified population is now known as M1 ipRGCs and project predominantly to brain regions involved in non-image forming visual functions, whereas the non-M1 ipRGCs show widespread projections to areas in the brain important for image formation. ipRGC subtypes express varying levels of the melanopsin protein and have different patterns of dendrite stratification in the inner plexiform layer (IPL)27, 28, 146, 147, indicating

LeGates, T.A.; Fernandez, D.C.; Hattar, S

2014-01-01

221

The circadian rhythm of salivary cortisol in growing pigs: effects of age, gender, and stress.  

PubMed

This experiment was designed to examine circadian rhythmicity of cortisol in saliva of growing pigs, in relation to age, gender, and (time of) stressor application. Additionally, the acute cortisol response to a stressor was studied. Five groups, each consisting of 3 barrows and 3 gilts, were involved in the experiment. In a Control Group, saliva samples were taken at 1-h intervals at 12, 16, 20, and 24 weeks of age. Within 1 week, rhythmicity of cortisol was assessed during two 24-h spans (Monday and Friday). Rhythm characteristics were evaluated by cosinor analysis, describing the rhythm by several parameters. In 2 groups at 12 weeks and 2 other groups at 20 weeks of age, a stressor was applied (4 h of isolation) on Thursday morning or evening. Again, rhythmicity was assessed on Monday and Friday by sampling at 2-h intervals. Acute cortisol effects were studied by sampling at several time-points during isolation. Between 12 and 24 weeks of age, basal cortisol concentrations decreased and a rather stable and adult circadian rhythm was reached at 20 weeks of age. Average basal cortisol concentrations were higher in barrows than in gilts. Furthermore, after isolation, the amplitude of the rhythm was increased in barrows but was unchanged in gilts. The rhythm was more unstable and the maximum value tended to shift only after evening isolation. Stressor timing, but also age, was found to affect average cortisol concentrations. Moreover, stressor timing was important for the acute cortisol response: the increase was higher in the morning. The results of this study emphasize the importance of considering the circadian rhythmicity of cortisol, in relation to age, gender, and (time of) stressor application, when studying the cortisol response of animals to stressors. PMID:9272674

Ruis, M A; Te Brake, J H; Engel, B; Ekkel, E D; Buist, W G; Blokhuis, H J; Koolhaas, J M

1997-09-01

222

The circadian rest-activity rhythm, a potential safety pharmacology endpoint of cancer chemotherapy.  

PubMed

The robustness of the circadian timing system (CTS) was correlated to quality of life and predicted for improved survival in cancer patients. However, chemotherapy disrupted the CTS according to dose and circadian timing in mice. A continuous and repeated measures longitudinal design was implemented here to characterize CTS dynamics in patients receiving a fixed circadian-based chemotherapy protocol. The rest-activity rhythm of 49 patients with advanced cancer was monitored using a wrist actigraph for 13 days split into four consecutive spans of 3-4 days each, i.e., before, during, right after and late after a fixed chronotherapy course. The relative amount of activity in bed vs. out of bed (ICircadian disruption (Irhythm parameters being worsened in the whole group of patients (p < 0.05). Mean parameter values subsequently recovered to near baseline values. The occurrence of circadian disruption on chemotherapy was associated with a higher risk of clinically relevant fatigue (p = 0.028) or body weight loss (p = 0.05). Four CTS dynamic patterns characterized treatment response including no change (9.5% of the patients); improvement (14.3%); alteration and complete recovery (31%) or sustained deterioration (45%), possibly due to inadequate chronotherapy dosing and/or timing. Improved clinical tolerability could result from the minimization of circadian disruption through the personalization of chronotherapy delivery. PMID:24510611

Ortiz-Tudela, Elisabet; Iurisci, Ida; Beau, Jacques; Karaboue, Abdoulaye; Moreau, Thierry; Rol, Maria Angeles; Madrid, Juan Antonio; Lévi, Francis; Innominato, Pasquale F

2014-06-01

223

Classical genetic analysis of circadian body temperature rhythms in mice  

Microsoft Academic Search

Classical genetic analysis of a cross between the C57BL\\/6J and the C3H\\/21bg inbred strains was used to examine the relative amounts of additive genetic and dominance variance for traits associated with the cricadian rhythm of body temperature. Traits involved with the timing mechanism (amplitude, time of peak temperature, and degree to which lights-off was anticipated) exhibited substantial heritability and little

Michael S. Connolly; Carol B. Lynch

1983-01-01

224

Pinealectomy shortens resynchronisation times of house sparrow ( Passer domesticus) circadian rhythms  

NASA Astrophysics Data System (ADS)

In many birds periodic melatonin secretion by the pineal organ is essential for the high-amplitude self-sustained output of the circadian pacemaker, and thus for the persistence of rhythmicity in 24 h oscillations controlled by it. The elimination of the pineal melatonin rhythm, or a reduction of its amplitude, renders the circadian pacemaker a less self-sustained, often highly damped, oscillatory system. A reduction in the degree of self-sustainment of a rhythm should not only increase its range of entrainment but also shorten the resynchronization times following phase-shifts of the zeitgeber. This hypothesis has not yet been directly tested. We therefore carried out the present study in which house sparrows (Passer domesticus) were subjected to both 6-h advance and 6-h delay phase-shifts of the light-dark cycle before and after the pinealectomy, and the rhythms in locomotion and feeding were recorded. The results indicate that following the delay, but not the advance, phase shift, resynchronization times were significantly shorter after pinealectomy. The dependence of resynchronization times on the presence or absence of the pineal organ is not only of theoretical interest but might also be of functional significance in the natural life of birds. A reduction or elimination of the amplitude of the melatonin secretion rhythm by the pineal organ might be responsible for faster adjustment to changes in zeitgeber conditions in nature.

Kumar, Vinod; Gwinner, Eberhard

2005-09-01

225

Nonlinear dynamics of the CAM circadian rhythm in response to environmental forcing.  

PubMed

Crassulacean acid metabolism (CAM) photosynthesis functions as an endogenous circadian rhythm coupled to external environmental forcings of energy and water availability. This paper explores the nonlinear dynamics of a new CAM photosynthesis model (Bartlett et al., 2014) and investigates the responses of CAM plant carbon assimilation to different combinations of environmental conditions. The CAM model (Bartlett et al., 2014) consists of a Calvin cycle typical of C3 plants coupled to an oscillator of the type employed in the Van der Pol and FitzHugh-Nagumo systems. This coupled system is a function of environmental variables including leaf temperature, leaf moisture potential, and irradiance. Here, we explore the qualitative response of the system and the expected carbon assimilation under constant and periodically forced environmental conditions. The model results show how the diurnal evolution of these variables entrains the CAM cycle with prevailing environmental conditions. While constant environmental conditions generate either steady-state or periodically oscillating responses in malic acid uptake and release, forcing the CAM system with periodic daily fluctuations in light exposure and leaf temperature results in quasi-periodicity and possible chaos for certain ranges of these variables. This analysis is a first step in quantifying changes in CAM plant productivity with variables such as the mean temperature, daily temperature range, irradiance, and leaf moisture potential. Results may also be used to inform model parametrization based on the observed fluctuating regime. PMID:25542971

Hartzell, Samantha; Bartlett, Mark S; Virgin, Lawrence; Porporato, Amilcare

2015-03-01

226

Circadian rhythm of core body temperature in subjects with chronic fatigue syndrome.  

PubMed

The pathophysiological basis for chronic fatigue syndrome (CFS) remains poorly understood. Certain symptoms of CFS, namely fatigue, neurocognitive symptoms and sleep disturbance, are similar to those of acute jet lag and shift work syndromes thus raising the possibility that CFS might be a condition associated with disturbances in endogenous circadian rhythms. In this study, we tested this hypothesis by examining the circadian rhythm of core body temperature (CBT) in CFS and control subjects. Continuous recordings of CBT were obtained every 5 min over 48 h in a group of 10 subjects who met the Center for Disease Control (CDC) definition of CFS and 10 normal control subjects. Subjects in the two groups were age, sex and weight-matched and were known to have normal basal metabolic rates and thyroid function. CBT recordings were performed under ambulatory conditions in a clinical research centre with the use of an ingestible radio frequency transmitter pill and a belt-worn receiver-logger. CBT time series were analysed by a cosinor analysis and by a harmonic-regression-plus-correlated-noise model to estimate the mean, amplitude and phase angle of the rhythm. The goodness of fit of each model was also compared using the Akaike Information Criterion (AIC) and sigma2. Average parameters for each group were compared by Student's t-test. By cosinor analysis, the only significant difference between CFS and control groups was in the phase angle of the third harmonic (P=0.02). The optimal harmonic-regression-plus-correlated-noise models selected were ARMA(1,1): control 7, CFS 6; ARMA(2,0): control 1, CFS 4; and ARMA(2,1): control 2 subjects. The optimal fit ARMA model contained two harmonics in eight of 10 control subjects but was more variable in the CFS subjects (1 harmonic: 5 subjects; 2 harmonics: 1 subject; 3 harmonics: 4 subjects). The goodness of fit measures for the optimal ARMA model were also better in the control than the CFS group, but the differences were not statistically significant. We conclude that, measured under ambulatory conditions, the circadian rhythm of CBT in CFS is nearly indistinguishable from that of normal control subjects although there was a tendency for greater variability in the rhythm. Hence, it is unlikely that the symptoms of CFS are because of disturbance in the circadian rhythm of CBT. PMID:11318826

Hamilos, D L; Nutter, D; Gershtenson, J; Ikle, D; Hamilos, S S; Redmond, D P; Di Clementi, J D; Schmaling, K B; Jones, J F

2001-03-01

227

Manipulating the sleep-wake cycle and circadian rhythms to improve clinical management of major depression  

PubMed Central

Background Clinical psychiatry has always been limited by the lack of objective tests to substantiate diagnoses and a lack of specific treatments that target underlying pathophysiology. One area in which these twin failures has been most frustrating is major depression. Due to very considerable progress in the basic and clinical neurosciences of sleep-wake cycles and underlying circadian systems this situation is now rapidly changing. Discussion The development of specific behavioral or pharmacological strategies that target these basic regulatory systems is driving renewed clinical interest. Here, we explore the extent to which objective tests of sleep-wake cycles and circadian function - namely, those that measure timing or synchrony of circadian-dependent physiology as well as daytime activity and nighttime sleep patterns - can be used to identify a sub-class of patients with major depression who have disturbed circadian profiles. Summary Once this unique pathophysiology is characterized, a highly personalized treatment plan can be proposed and monitored. New treatments will now be designed and old treatments re-evaluated on the basis of their effects on objective measures of sleep-wake cycles, circadian rhythms and related metabolic systems. PMID:23521808

2013-01-01

228

Visual responses in teleosts. Electroretinograms, eye movements, and circadian rhythms  

PubMed Central

We have recorded ocular potentials in response to brief flashes of light from two teleosts, the white perch (Roccus americana) and the green sunfish (Lepomis cyanellus). The animals were respired and maintained in an alert state for up to 2 d. Responses were recorded with corneal and transcleral electrodes. The responses of green sunfish were composed of electroretinogram (ERG) and eye movement potentials, whereas the responses in white perch contained only the ERG. Injection of curare abolished the sunfish eye movement potentials, unmasking the ERG. Observation under infrared illumination established a direct relationship between eye movements and the fast potentials which could be abolished by curare. We found no evidence of circadian changes in the amplitude of the ERG b-wave of either species. However, our results combined with those of a previous study of sunfish ocular potentials (Dearry, A., and B. Barlow, Jr. 1987. J. Gen. Physiol. 89: 745-770) suggest that the sunfish visual system exhibits rhythmic changes in oculomotor responses, which appear to be controlled by a circadian oscillator. PMID:1512556

1992-01-01

229

Visual responses in teleosts. Electroretinograms, eye movements, and circadian rhythms.  

PubMed

We have recorded ocular potentials in response to brief flashes of light from two teleosts, the white perch (Roccus americana) and the green sunfish (Lepomis cyanellus). The animals were respired and maintained in an alert state for up to 2 d. Responses were recorded with corneal and transcleral electrodes. The responses of green sunfish were composed of electroretinogram (ERG) and eye movement potentials, whereas the responses in white perch contained only the ERG. Injection of curare abolished the sunfish eye movement potentials, unmasking the ERG. Observation under infrared illumination established a direct relationship between eye movements and the fast potentials which could be abolished by curare. We found no evidence of circadian changes in the amplitude of the ERG b-wave of either species. However, our results combined with those of a previous study of sunfish ocular potentials (Dearry, A., and B. Barlow, Jr. 1987. J. Gen. Physiol. 89: 745-770) suggest that the sunfish visual system exhibits rhythmic changes in oculomotor responses, which appear to be controlled by a circadian oscillator. PMID:1512556

McMahon, D G; Barlow, R B

1992-07-01

230

Generation of masticatory rhythm in the brainstem  

Microsoft Academic Search

Mastication is a typical rhythmical behavior in mammals. Like respiration, it is now generally accepted that the motor command for the basic pattern of rhythmical oral-facial movements is generated by a neuronal population in the brainstem (central pattern generator, CPG). The central pattern generation of rhythmical masticatory movements can be divided into three processes: (1) generation of the masticatory rhythm,

Yoshio Nakamura; Nobuo Katakura

1995-01-01

231

The Effects of Hydrogen Peroxide on the Circadian Rhythms of Microcystis aeruginosa  

PubMed Central

Background The cyanobacterium Microcystis aeruginosa is one of the principal bloom-forming cyanobacteria present in a wide range of freshwater ecosystems. M. aeruginosa produces cyanotoxins, which can harm human and animal health. Many metabolic pathways in M. aeruginosa, including photosynthesis and microcystin synthesis, are controlled by its circadian rhythms. However, whether xenobiotics affect the cyanobacterial circadian system and change its growth, physiology and biochemistry is unknown. We used real-time PCR to study the effect of hydrogen peroxide (H2O2) on the expression of clock genes and some circadian genes in M. aeruginosa during the light/dark (LD) cycle. Results The results revealed that H2O2 changes the expression patterns of clock genes (kaiA, kaiB, kaiC and sasA) and significantly decreases the transcript levels of kaiB, kaiC and sasA. H2O2 treatment also decreased the transcription of circadian genes, such as photosynthesis-related genes (psaB, psbD1 and rbcL) and microcystin-related genes (mcyA, mcyD and mcyH), and changed their circadian expression patterns. Moreover, the physiological functions of M. aeruginosa, including its growth and microcystin synthesis, were greatly influenced by H2O2 treatment during LD. These results indicate that changes in the cyanobacterial circadian system can affect its physiological and metabolic pathways. Conclusion Our findings show that a xenobiotic can change the circadian expression patterns of its clock genes to influence clock-controlled gene regulation, and these influences are evident at the level of cellular physiology. PMID:22413018

Yu, Shuqiong; Pan, Xiangjie; Wu, Tao; Fu, Zhengwei

2012-01-01

232

Vascular circadian rhythms in a mouse vascular smooth muscle cell line (Movas-1).  

PubMed

The circadian system in mammals is a hierarchy of oscillators throughout the organism that are coordinated by the circadian clock in the hypothalamic suprachiasmatic nucleus. Peripheral clocks act to integrate time-of-day information from neural or hormonal signals, regulating gene expression, and, subsequently, organ physiology. However, the mechanisms by which the central clock communicates with peripheral oscillators are not understood and are likely tissue specific. In this study, we establish a mouse vascular cell model suitable for investigations of these mechanisms at a molecular level. Using the immortalized vascular smooth muscle cell line Movas-1, we determined that these cells express the circadian clock machinery with robust rhythms in mRNA expression over a 36-h period after serum shock synchronization. Furthermore, norepinephrine and forskolin were able to synchronize circadian rhythms in bmal1. With synchronization, we observed cycling of specific genes, including the tissue inhibitor of metalloproteinase 1 and 3 (timp1, timp3), collagen 3a1 (col3a1), transgelin 1 (sm22alpha), and calponin 1 (cnn1). Diurnal expression of these genes was also found in vivo in mouse aortic tissue, using microarray and real-time RT-PCR analysis. Both of these revealed ultradian rhythms in genes similar to the cycling observed in Movas-1 in vitro. These findings highlight the cyclical nature of structurally important genes in the vasculature that is similar both in vivo and in vitro. This study establishes the Movas-1 cells as a novel cell model from which to further investigate the molecular mechanisms of clock regulation in the vasculature. PMID:18768761

Chalmers, Jennifer A; Martino, Tami A; Tata, Nazneen; Ralph, Martin R; Sole, Michael J; Belsham, Denise D

2008-11-01

233

Effects of long-term microgravity exposure in space on circadian rhythms of heart rate variability.  

PubMed

We evaluated their circadian rhythms using data from electrocardiographic records and examined the change in circadian period related to normal RR intervals for astronauts who completed a long-term (?6-month) mission in space. The examinees were seven astronauts, five men and two women, from 2009 to 2010. Their mean?±?SD age was 52.0?±?4.2 years (47-59?yr). Each stayed in space for more than 160 days; their average length of stay was 172.6?±?14.6 days (163-199 days). We conducted a 24-h Holter electrocardiography before launch (Pre), at one month after launch (DF1), at two months after launch (DF2), at two weeks before return (DF3), and at three months after landing (Post), comparing each index of frequency-domain analysis and 24-h biological rhythms of the NN intervals (normal RR intervals). Results show that the mean period of Normal Sinus (NN) intervals was within 24?±?4?h at each examination. Inter-individual variability differed among the stages, being significantly smaller at DF3 (Pre versus DF1 versus DF3 versus Post?=?22.36?±?2.50 versus 25.46?±?4.37 versus 22.46?±?1.75 versus 26.16?±?7.18?h, p?circadian rhythms were disturbed until one month had passed in space, well-scheduled sleep and wake rhythms and meal times served as synchronizers. PMID:25392280

Yamamoto, Naomune; Otsuka, Kuniaki; Kubo, Yutaka; Hayashi, Mitsutoshi; Mizuno, Koh; Ohshima, Hiroshi; Mukai, Chiaki

2014-11-13

234

The 24-h growth hormone rhythm in men: sleep and circadian influences questioned.  

PubMed

The 24-h rhythm of growth hormone (GH) is thought to be controlled primarily by sleep processes with a weak circadian component. This concept has been recently questioned in sleep-deprived persons. To test the notion of a high sleep-dependency of GH release, we established simultaneous 24-h rhythms of GH and melatonin, a circadian marker, in night workers who form a model for challenging sleep and circadian processes. Ten day-active subjects and 11 night workers were studied during their usual sleep-wake schedule, with sleep from 23:00 to 07:00 hours and 07:00 to 15:00 hours, respectively. Experiments were conducted in sleep rooms under continuous nutrition, bed rest, and dim light. Melatonin and GH were measured every 10 min over 24 h. In day-active subjects, melatonin and GH showed the well-known 24-h profiles, with a major sleep-related GH pulse accounting for 52.8 +/- 3.5% of the 24-h GH production and the onset of the melatonin surge occurring at 21:53 hours +/- 18 min. In night workers, melatonin showed variable circadian adaptation, with the onset of secretion varying between 21:45 and 05:05 hours. The sleep-related GH pulse was lowered, but the reduction was compensated for by the emergence of large individual pulses occurring unpredictably during waking periods, so that the total amount of GH secreted during the 24 h was constant. One cannot predict the degree of GH adaptation from the highly variable melatonin shift. These results argue against the concept that sleep processes exert a predominant influence on GH release whatever the conditions. When sleep and circadian processes are misaligned, the blunting of the sleep-related GH pulse is counteracted, as in sleep-deprived persons, by a compensatory mechanism promoting GH pulses during wakefulness. PMID:15339260

Brandenberger, Gabrielle; Weibel, Laurence

2004-09-01

235

Circadian rhythm of mechanically mediated differentiation of osteoblasts  

NASA Technical Reports Server (NTRS)

The differential of osteoblasts in response to orthodontic pressure in the periodontal ligament of the maxillary-first-molar periodontal ligaments of 12-h-light/dark-entrained 7-wk-old male Simonsen outbred rats is measured by (H-3)-Thymidine nuclear-volume morphometry (Roberts et al., 1983) at hourly intervals throughout the circadian cycle. The results are presented in graphs and discussed. Preosteoblast large nuclei (D-cells) are found to synthesize DNA mainly in light and to divide in the following dark period, while small-nucleus osteoprogenitors (A-cells) synthesize in darkness and divide in light. These findings are seen as consistent with a model in which the sequence of proliferation and differentiation requires at least 60 h (five 12-h periods) and the shift from A to D cells lasts about 19 h.

Roberts, W. E.; Mozsary, P. G.; Klingler, E.

1984-01-01

236

[Peculiarities of circadian rhythms in plants from different geographical latitudes].  

PubMed

1 Two species of plants (Taraxacum arcticum and Arnica angustifolia), collected in Spitsbergen (geogr. latitude 76-80 degrees) exhibit endogenous circadian leaf movements but also movements with shorter periods. Astragalus frigidus, A. alpinus and Hedysarum hedysaroides, collected in arctic regions of continental Europe, also show endogenous diurnal leaf movements. 2. In most of the species tested, there was no difference in the length of the free running periods of plants from arctic and Central-European regions. This is also the case when individuals of the same species collected in different regions are compared. However, in Taraxacum arcticum the period is shorter than in T. officinale In general, under constant conditions the circadian oscillations of arctic plants persist for a shorter period than those of other plants. 3. The free running periods of several of the investigated species from tropical regions are much longer than 24 hours, i.e., much longer than those of species from Central-European and arctic regions. 4. The free running periods of several tropical species are temperature-independent (Erythrina senegalensis, Albizzia lophanta, Rhynchosia memmonia, Vigna catjang, Phaseolus multiflorus). In other tropical species, however, the periods decrease rather strongly with increasing temperature (Phaseolus mungo, Canavalia obtusifolia, Clitoria ternatea, Dolichos lablab, Vigna sesquipedalis, Dolichos zebra). The temperature does not influence the amplitudes in Phaseolus mungo and Vigna sesquipedalis, but it strongly influences the amplitudes in Erythrina senegalensis, in LD-cycles as well as in continuous light. 5. The arctic plant Astragalus frigidus still shows free running oscillations at 12°C, whereas several tropical species oscillate only at temperatures above 17°C. 6. The differences in the periods of tropical and non-tropical species (see under [3]) disappear if the plants are compared not at the same temperature but at temperatures which are optimal for them. If tropical plants are tested 27°C and Central-European and arctic species at 17°C, the periods always approach the value of 24 hours. PMID:24557984

Mayer, W

1966-09-01

237

Disruption of cardiovascular circadian rhythms in mice post myocardial infarction: relationship with central angiotensin II receptor expression  

PubMed Central

Abstract Angiotensin II (Ang II) is well known to participate in the abnormal autonomic cardiovascular control that occurs during the development of chronic heart failure (CHF). Disrupted cardiovascular circadian rhythm in CHF is also well accepted; however, the mechanisms underlying and the role of central Ang II type 1 receptors (AT1R) and oxidative stress in mediating such changes are not clear. In a post myocardial infarction (MI) CHF mouse model we investigated the circadian rhythm for mean arterial pressure (MAP), heart rate (HR), and baroreflex sensitivity (BRS) following MI. The cardiovascular parameters represent the middle 6?h averages during daytime (6:00–18:00) and nighttime (18:00–6:00). HR increased with the severity of CHF reaching its maximum by 12 weeks post?MI; loss of circadian HR and BRS rhythms were observed as early as 4 weeks post?MI in conjunction with a significant blunting of the BRS and an upregulation in the AT1R and gp91phox proteins in the brainstem. Loss of MAP circadian rhythm was observed 8 weeks post?MI. Circadian AT1R expression was demonstrated in sham animals but was lost 8 weeks following MI. Losartan reduced AT1R expression in daytime (1.18 ± 0.1 vs. 0.85 ± 0.1; P < 0.05) with a trend toward a reduction in the AT1R mRNA expression in the nighttime (1.2 ± 0.1 vs. 1.0 ± 0.1; P > 0.05) but failed to restore circadian variability. The disruption of circadian rhythm for HR, MAP and BRS along with the upregulation of AT1 and gp91phox suggests a possible role for central oxidative stress as a mediator of circadian cardiovascular parameters in the post?MI state. PMID:25413327

Mousa, Tarek M.; Schiller, Alicia M.; Zucker, Irving H.

2014-01-01

238

Ecdysis behaviors and circadian rhythm of ecdysis in the stick insect, Carausius morosus.  

PubMed

Successful ecdysis in insects depends on proper timing and sequential activation of an elaborate series of motor programs driven by a relatively conserved network of neuropeptides. The behaviors must be activated at the appropriate times to ensure successful loosening and shedding of the old cuticle, and can be influenced by environmental cues in the form of immediate sensory feedback and by circadian rhythms. We assessed the behaviors, components of the neural network and the circadian basis of ecdysis in the stick insect, Carausius morosus. C. morosus showed many of the characteristic pre-ecdysis and ecdysis behaviors previously described in crickets and locusts. Ecdysis was described in three phases, namely the (i) preparatory or pre-ecdysis phase, (ii) the ecdysial phase, and (iii) the post-ecdysis or exuvial phase. The frequencies of push-ups and sways during the preparatory phase were quantified as well as durations of all the phases. The regulation of ecdysis appeared to act via elevation of cGMP, as described in many other insects, although eclosion hormone-like immunoreactivity was not noted using a lepidopteran antiserum. Finally, C. morosus showed a circadian rhythm to the onset of ecdysis, with ecdysis occurring just prior to or at lights on. Ecdysis could be induced precociously with mechanical stimulation. PMID:25450561

Wadsworth, Tracy; Carriman, Andrew; Gutierrez, Alba A; Moffatt, Christopher; Fuse, Megumi

2014-12-01

239

Corkscrews and singularities in fruitflies - Resetting behavior of the circadian eclosion rhythm.  

NASA Technical Reports Server (NTRS)

Description of experiments undertaken to define the phase-resetting behavior of the circadian rhythm of pupal eclosion in populations of fruitflies. An attempt is made to determine how and why the resetting response depends on the duration of a standard perturbation as well as on the time at which it is given. Plotting a three-dimensional graph of the measured emergence centroids vs the stimulus variables, the data are found to spiral up around a vertical rotation axis. Using a computer, a smooth surface, called the resetting surface, which approximately fits the helicoidal cloud of data points, is obtained and is shown to be best described as a vertical corkscrew linking together tilted planes. This corkscrew feature of the resetting surface is taken to indicate that there is an isolated perturbation following which there is either no circadian rhythm of emergence in the steady state, or one of unpredictable phase. A hypothesis concerning the clock dynamics underlying the eclosion rhythm is briefly sketched which encompasses the main features of known resetting data using single discrete pulses of any perturbing agent.

Winfree, A. T.

1971-01-01

240

The Circadian Rhythm in Photosynthesis in Acetabularia in the Presence of Actinomycin D, Puromycin, and Chloramphenicol  

PubMed Central

Anucleate Acetabularia crenulata shows a circadian rhythm in photosynthesis. In this study, an oxygen electrode was employed to measure this photosynthetic rhythm in the presence and absence of the inhibitors, actinomycin D, chloramphenicol, and puromycin. High concentrations of the inhibitors were used: actinomycin D, 20–40 µg ml-1 puromycin, 30 and 100 µg ml-1; and chloramphenicol, 250 µg ml-1. The effectiveness of these inhibitors on protein synthesis was also measured under the same conditions used for the determination of rhythmicity. In spite of large effects of all three inhibitors on the incorporation of 14C leucine, no effect on the period or the phase of the photosynthetic rhythm was observed. The higher concentration of puromycin and chloramphenicol produced toxic effects which were expressed as a reduction in the amount of photosynthesis, but rhythmicity was still apparent. After 3 or 4 days' exposure to actinomycin, Acetabularia became resistant to its effect. Recovery was also observed in the ability to incorporate leucine. The implications of these results for theories of the basic oscillator responsible for circadian rhythmicity are discussed. PMID:11526851

Sweeney, Beatrice M.; Tuffli, Charles F.; Rubin, Richard H.

1967-01-01

241

Independence of Genetic Geographical Variation between Photoperiodic Diapause, Circadian Eclosion Rhythm, and Thr-Gly Repeat Region of the Period Gene in Drosophila littoralis  

Microsoft Academic Search

Drosophila littoralis is a latitudinally widespread European species of the Drosophila virilis group. The species has ample genetic variation in photoperiodism (adult diapause) and circadian rhythmicity (pupal eclosion rhythm), with adaptive latitudinal clines in both of them. The possible common genetic basis between the variability of photoperiodism and circadian rhythms was studied by a long-term crossing experiment. A northern strain

P. Lankinen; P. Forsman

2006-01-01

242

Does Disruption of Circadian Rhythms Contribute to Beta-Cell Failure in Type 2 Diabetes?  

PubMed Central

Type 2 diabetes mellitus (T2DM) is a complex metabolic disease characterized by the loss of beta-cell secretory function and mass. The pathophysiology of beta-cell failure in T2DM involves a complex interaction between genetic susceptibilities and environmental risk factors. One environmental condition that is gaining greater appreciation as a risk factor for T2DM is the disruption of circadian rhythms (eg, shift-work and sleep loss). In recent years, circadian disruption has become increasingly prevalent in modern societies and consistently shown to augment T2DM susceptibility (partly mediated through its effects on pancreatic beta-cells). Since beta-cell failure is essential for development of T2DM, we will review current work from epidemiologic, clinical, and animal studies designed to gain insights into the molecular and physiological mechanisms underlying the predisposition to beta-cell failure associated with circadian disruption. Elucidating the role of circadian clocks in regulating beta-cell health will add to our understanding of T2DM pathophysiology and may contribute to the development of novel therapeutic and preventative approaches. PMID:24532160

Rakshit, Kuntol; Thomas, Anthony P.

2014-01-01

243

Control mechanisms of circadian rhythms in body composition: Implications for manned spaceflight  

NASA Technical Reports Server (NTRS)

The mechanisms that underlie the circadian variations in electrolyte content in body fluid compartments were investigated, and the mechanisms that control the oscillations were studied in order to investigate what effects internal desynchronization in such a system would have during manned space flight. The studies were performed using volunteer human subjects and squirrel monkeys. The intercompartmental distribution of potassium was examined when dietary intake, activity, and posture are held constant throughout each 24-hour day. A net flux of potassium was observed out of the body cell mass during the day and a reverse flux from the extracellular fluid into the body cell mass during the night, counterbalanced by changes in urinary potassium excretion. Experiments with monkeys provided evidence for the synchronization of renal potassium excretion by the rhythm of cortisol secretion with the light-dark cycle. Three models of the circadian timing system were formalized.

Ede, M. C. M.

1975-01-01

244

Dynamics of three coupled van der Pol oscillators with application to circadian rhythms  

NASA Astrophysics Data System (ADS)

In this work we study a system of three van der Pol oscillators. Two of the oscillators are identical, and are not directly coupled to each other, but rather are coupled via the third oscillator. We investigate the existence of the in-phase mode in which the two identical oscillators have the same behavior. To this end we use the two variable expansion perturbation method (also known as multiple scales) to obtain a slow flow, which we then analyze using the computer algebra system MACSYMA and the numerical bifurcation software AUTO. Our motivation for studying this system comes from the presence of circadian rhythms in the chemistry of the eyes. We model the circadian oscillator in each eye as a van der Pol oscillator. Although there is no direct connection between the two eyes, they are both connected to the brain, especially to the pineal gland, which is here represented by a third van der Pol oscillator.

Rompala, Kevin; Rand, Richard; Howland, Howard

2007-08-01

245

Circadian rhythms of hydraulic conductance and growth are enhanced by drought and improve plant performance  

PubMed Central

Circadian rhythms enable plants to anticipate daily environmental variations, resulting in growth oscillations under continuous light. Because plants daily transpire up to 200% of their water content, their water status oscillates from favourable during the night to unfavourable during the day. We show that rhythmic leaf growth under continuous light is observed in plants that experience large alternations of water status during an entrainment period, but is considerably buffered otherwise. Measurements and computer simulations show that this is due to oscillations of plant hydraulic conductance and plasma membrane aquaporin messenger RNA abundance in roots during continuous light. A simulation model suggests that circadian oscillations of root hydraulic conductance contribute to acclimation to water stress by increasing root water uptake, thereby favouring growth and photosynthesis. They have a negative effect in favourable hydraulic conditions. Climate-driven control of root hydraulic conductance therefore improves plant performances in both stressed and non-stressed conditions. PMID:25370944

Caldeira, Cecilio F.; Jeanguenin, Linda; Chaumont, François; Tardieu, François

2014-01-01

246

Circadian rhythms and metabolic syndrome: from experimental genetics to human disease  

PubMed Central

The incidence of the metabolic syndrome represents a spectrum of disorders that continue to increase across the industrialized world. Both genetic and environmental factors contribute to metabolic syndrome and recent evidence has emerged to suggest that alterations in circadian systems and sleep participate in the pathogenesis of the disease. In this review, we highlight studies at the intersection of clinical medicine and experimental genetics that pinpoint how perturbations of the internal clock system, and sleep, constitute risk factors for disorders including obesity, diabetes mellitus, cardiovascular disease, thrombosis and even inflammation. An exciting aspect of the field has been the integration of behavioural and physiological approaches, and the emerging insight into both neural and peripheral tissues in disease pathogenesis. Consideration of the cell and molecular links between disorders of circadian rhythms and sleep with metabolic syndrome has begun to open new opportunities for mechanism-based therapeutics. PMID:20167942

Maury, Eleonore; Ramsey, Kathryn Moynihan; Bass, Joseph

2009-01-01

247

Wrist actimetry circadian rhythm as a robust predictor of colorectal cancer patients survival.  

PubMed

The disruption of the circadian timing system (CTS), which rhythmically controls cellular metabolism and proliferation, accelerated experimental cancer progression. A measure of CTS function in cancer patients could thus provide novel prediction information for outcomes, and help to identify novel specific therapies. The rest-activity circadian rhythm is a reliable and non-invasive CTS biomarker, which was monitored using a wrist watch accelerometer for 2 days in 436 patients with metastatic colorectal cancer. The relative percentage of activity in-bed versus out-of-bed (I < O) constituted the tested CTS measure, whose prognostic value for overall survival (OS) and progression-free survival (PFS) was determined in a pooled analysis of three patient cohorts with different treatment exposures. Median OS was 21.6 months [17.8-25.5] for patients with I < O above the median value of 97.5% as compared to 11.9 months [10.4-13.3] for those with a lower I < O (Log-rank p < 0.001). Multivariate analyses retained continuous I < O as a joint predictor of both OS and PFS, with respective hazard ratios (HR) of 0.954 (p < 0.001) and 0.970 (p < 0.001) for each 1% increase in I < O. HRs had similar values in all the patient subgroups tested. The circadian physiology biomarker I < O constitutes a robust and independent quantitative predictor of cancer patient outcomes, that can be easily and cost-effectively measured during daily living. Interventional studies involving 24-h schedules of clock-targeted drugs, light intensity, exercise and/or meals are needed for testing the relevance of circadian synchronization for the survival of patients with disrupted rhythms. PMID:24927369

Lévi, Francis; Dugué, Pierre-Antoine; Innominato, Pasquale; Karaboué, Abdoulaye; Dispersyn, Garance; Parganiha, Arti; Giacchetti, Sylvie; Moreau, Thierry; Focan, Christian; Waterhouse, Jim; Spiegel, David

2014-10-01

248

Circadian rhythm of CSF monoamines and hypocretin-1 in restless legs syndrome and Parkinson's disease.  

PubMed

The symptoms of restless legs syndrome (RLS) have a circadian pattern and central nervous system dopamine has been implicated in the pathogenesis of the condition. We sought to characterize circadian variation in dopamine and related compounds in human cerebro-spinal fluid (CSF). CSF was continuously withdrawn for 22 h from an implanted lumbar intradural catheter and sampled from three patients with RLS, three patients with Parkinson's disease (PD) and three healthy volunteers. Patients had moderate disease severity and took no medications. We assayed CSF dopamine (DA), homovanillic acid (HVA), dihydroxy-phenylacetic acid (DOPAC) and 5-hydroxyindole acetic acid (5-HIAA) from samples every 30 min by reversed-phase HPLC coupled with electrochemical detection. We also measured CSF levels of hypocretin-1 every hour by RIA. The procedure was well-tolerated. One patient ended the study early due to lumbar radicular pain and was not included in the analysis. There were no changes in CSF cell counts or protein levels from the first to the last samples. There was no difference in any of the compounds between groups, so we fit 24-h cosines to examine if the entire group had significant phase consistency. There was a peak for dopamine at 10 a.m. (p<0.025) and for HVA at 2 p.m. (p<0.01), but no evidence of a significant 24-h rhythm for DOPAC, 5-HIAA, the HVA/5-HIAA ratio, or hypocretin-1. These results demonstrate a circadian rhythm for CSF dopamine and HVA concentrations in humans, with higher levels in the daytime than at nighttime. This circadian variation could underlie the symptoms of RLS and sleep-related variation in motor function in PD. PMID:18207455

Poceta, J Steven; Parsons, Loren; Engelland, Scott; Kripke, Daniel F

2009-01-01

249

Ageing and the circadian and homeostatic regulation of human sleep during forced desynchrony of rest, melatonin and temperature rhythms  

PubMed Central

The circadian timing system has been implicated in age-related changes in sleep structure, timing and consolidation in humans. We investigated the circadian regulation of sleep in 13 older men and women and 11 young men by forced desynchrony of polysomnographically recorded sleep episodes (total, 482; 9 h 20 min each) and the circadian rhythms of plasma melatonin and core body temperature. Stage 4 sleep was reduced in older people. Overall levels of rapid eye movement (REM) sleep were not significantly affected by age. The latencies to REM sleep were shorter in older people when sleep coincided with the melatonin rhythm. REM sleep was increased in the first quarter of the sleep episode and the increase of REM sleep in the course of sleep was diminished in older people. Sleep propensity co-varied with the circadian rhythms of body temperature and plasma melatonin in both age groups. Sleep latencies were longest just before the onset of melatonin secretion and short sleep latencies were observed close to the temperature nadir. In older people sleep latencies were longer close to the crest of the melatonin rhythm. In older people sleep duration was reduced at all circadian phases and sleep consolidation deteriorated more rapidly during the course of sleep, especially when the second half of the sleep episode occurred after the crest of the melatonin rhythm. The data demonstrate age-related decrements in sleep consolidation and increased susceptibility to circadian phase misalignment in older people. These changes, and the associated internal phase advance of the propensity to awaken from sleep, appear to be related to the interaction between a reduction in the homeostatic drive for sleep and a reduced strength of the circadian signal promoting sleep in the early morning. PMID:10087357

Dijk, Derk-Jan; Duffy, Jeanne F; Riel, Eymard; Shanahan, Theresa L; Czeisler, Charles A

1999-01-01

250

Pharmacology of Myopia and Potential Role for Intrinsic Retinal Circadian Rhythms  

PubMed Central

Despite the high prevalence and public health impact of refractive errors, the mechanisms responsible for ametropias are poorly understood. Much evidence now supports the concept that the retina is central to the mechanism(s) regulating emmetropization and underlying refractive errors. Using a variety of pharmacologic methods and well-defined experimental eye growth models in laboratory animals, many retinal neurotransmitters and neuromodulators have been implicated in this process. Nonetheless, an accepted framework for understanding the molecular and/or cellular pathways that govern postnatal eye development is lacking. Here, we review two extensively studied signaling pathways whose general roles in refractive development are supported by both experimental and clinical data: acetylcholine signaling through muscarinic and/or nicotinic acetylcholine receptors and retinal dopamine pharmacology. The muscarinic acetylcholine receptor antagonist atropine was first studied as an anti-myopia drug some two centuries ago, and much subsequent work has continued to connect muscarinic receptors to eye growth regulation. Recent research implicates a potential role of nicotinic acetycholine receptors; and the refractive effects in population surveys of passive exposure to cigarette smoke, of which nicotine is a constituent, support clinical relevance. Reviewed here, many puzzling results inhibit formulating a mechanistic framework that explains acetylcholine’s role in refractive development. How cholinergic receptor mechanisms might be used to develop acceptable approaches to normalize refractive development remains a challenge. Retinal dopamine signaling not only has a putative role in refractive development, its upregulation by light comprises an important component of the retinal clock network and contributes to the regulation of retinal circadian physiology. During postnatal development, the ocular dimensions undergo circadian and/or diurnal fluctuations in magnitude; these rhythms shift in eyes developing experimental ametropia. Long-standing clinical ideas about myopia in particular have postulated a role for ambient lighting, although molecular or cellular mechanisms for these speculations have remained obscure. Experimental myopia induced by the wearing of a concave spectacle lens alters the retinal expression of a significant proportion of intrinsic circadian clock genes, as well as genes encoding a melatonin receptor and the photopigment melanopsin. Together this evidence suggests a hypothesis that the retinal clock and intrinsic retinal circadian rhythms may be fundamental to the mechanism(s) regulating refractive development, and that disruptions in circadian signals may produce refractive errors. Here we review the potential role of biological rhythms in refractive development. While much future research is needed, this hypothesis could unify many of the disparate clinical and laboratory observations addressing the pathogenesis of refractive errors. PMID:23313151

Stone, Richard A.; Pardue, Machelle T.; Iuvone, P. Michael; Khurana, Tejvir S.

2013-01-01

251

Melatonin and the circadian rhythms of feeding and perch-hopping in the European starling, Sturnus vulgaris  

Microsoft Academic Search

The role of melatonin plasma titers in the control of free-running circadian rhythms was investigated in European starlings,Sturnus vulgaris, held in continuous dim light. Simultaneous recordings of plasma melatonin, perch-hopping and feeding activity revealed synchronous circadian variations in all three functions with high melatonin titers during resting and low titers during activity periods. Implanting birds with melatonin silastic capsules resulted

Hans J. A. Beldhuis; John P. Dittami; Eberhard Gwinner

1988-01-01

252

Local Administration of Serotonin Agonists Blocks Light-Induced Phase Advances of the Circadian Activity Rhythm in the Hamster  

Microsoft Academic Search

Circadian rhythms in mammals are synchronized to environmental light-dark cycles through a direct retinal projection to the suprachiasmatic nucleus (SCN), a circadian clock. This process is thought to be modulated by other afferents to the SCN, including a dense serotonergic projection from the midbrain raphe. Previous work from this laboratory demonstrated that a systemically administered 5-hydroxytry ptamine1A\\/7 (5-HT1A\\/7) agonist 8-hydroxy-2-(di-n-propylamino)tetralin

E. T. Weber; R. L. Gannon; M. A. Rea

1998-01-01

253

The pineal clock affects behavioral circadian rhythms but not photoperiodic induction in the Indian weaver bird ( Ploceus philippinus )  

Microsoft Academic Search

We investigated whether pineal is part of the circadian clock system which regulates circadian rhythms of activity and photosensitivity\\u000a in the Indian weaver bird (Ploceus philippinus). Two experiments were performed. The first experiment examined the induction of testicular growth, and androgen-dependent\\u000a beak pigmentation and luteinizing hormone (LH)-specific plumage coloration in pinealectomised (pinx) and sham-operated (sham)\\u000a birds exposed to short day

Sangeeta Rani; Sudhi Singh; Vinod Kumar

2005-01-01

254

The generation of respiratory rhythms in birds  

NASA Astrophysics Data System (ADS)

The generation of precise respiratory rhythms is vital for birds, which must generate specific pressure patterns to perform several activities, song being one of the most demanding ones. These rhythms emerge as the interaction between a peripheral system and a set of neural nuclei which control the action of expiratory and inspiratory muscles. A computational model was proposed recently to account for this interaction. In this work, we describe the set of solutions that this model can display as its parameters are varied, and compare experimental records of air sac pressure patterns with the predictions of the model.

Granada, A.; Gabitto, M.; García, G.; Alliende, J.; Méndez, J.; Trevisan, M. A.; Mindlin, G. B.

2006-11-01

255

Circadian Rhythms of Chloroplast Orientation and Photosynthetic Capacity in Ulva123  

PubMed Central

Ulva lactuca L. var. latissima (L.) Decandolle and var. rigida (C. Agardh) Le Jolis and U. mutabilis Foyn have a circadian rhythm of chloroplast orientation which results in large changes in the light-absorption properties of the thallus. During the day, the chloroplasts cover the outer face of the cells and absorbance is high. At night, the chloroplasts are along the side walls and absorbance is low. Enteromorpha linza (L.) J. Agardh, E. intestinalis (L.) Link, E. sp., and Monostroma grevillei (Thuret) Wittrock, members of the Ulvales, were not observed to have this rhythmic movement. Chloroplasts, when in the face position, could not be induced to move to the sides by high intensity light up to 80,000 lux. Unrelated to chloroplast position per se and light-absorption efficiency, there is a rhythm of photosynthetic capacity which peaks just before midday and which continues in constant darkness. Images PMID:16659613

Britz, Steven J.; Briggs, Winslow R.

1976-01-01

256

Circadian Rhythm Sleep Disorders: Part II, Advanced Sleep Phase Disorder, Delayed Sleep Phase Disorder, Free-Running Disorder, and Irregular Sleep-Wake Rhythm  

PubMed Central

Objective: This the second of two articles reviewing the scientific literature on the evaluation and treatment of circadian rhythm sleep disorders (CRSDs), employing the methodology of evidence-based medicine. We herein report on the accumulated evidence regarding the evaluation and treatment of Advamced Sleep Phase Disorder (ASPD), Delayed Sleep Phase Disorder (DSPD), Free-Running Disorder (FRD) and Irregular Sleep-Wake Rhythm ISWR). Methods: A set of specific questions relevant to clinical practice were formulated, a systematic literature search was performed, and relevant articles were abstracted and graded. Results: A substantial body of literature has accumulated that provides a rational basis the evaluation and treatment of CRSDs. Physiological assessment has involved determination of circadian phase using core body temperature and the timing of melatonin secretion. Behavioral assessment has involved sleep logs, actigraphy and the Morningness-Eveningness Questionnaire (MEQ). Treatment interventions fall into three broad categories: 1) prescribed sleep scheduling, 2) circadian phase shifting (“resetting the clock”), and 3) symptomatic treatment using hypnotic and stimulant medications. Conclusion: Circadian rhythm science has also pointed the way to rational interventions for CRSDs and these treatments have been introduced into the practice of sleep medicine with varying degrees of success. More translational research is needed using subjects who meet current diagnostic criteria. Citation: Sack R; Auckley D; Auger RR; Carskadon MA; Wright KP; Vitiello MV; Zhdanova IV. Circadian rhythm sleep disorders: Part II, advanced sleep phase disorder, delayed sleep phase disorder, free-running disorder, and irregular sleep-wake rhythm. SLEEP 2007;30(11):1484-1501. PMID:18041481

Sack, Robert L; Auckley, Dennis; Auger, R. Robert; Carskadon, Mary A.; Wright, Kenneth P.; Vitiello, Michael V.; Zhdanova, Irina V.

2007-01-01

257

Circadian Rhythms of Sense and Antisense Transcription in Sugarcane, a Highly Polyploid Crop  

PubMed Central

Commercial sugarcane (Saccharum hybrid) is a highly polyploid and aneuploid grass that stores large amounts of sucrose in its stem. We have measured circadian rhythms of sense and antisense transcription in a commercial cultivar (RB855453) using a custom oligoarray with 14,521 probes that hybridize to sense transcripts (SS) and 7,380 probes that hybridize to antisense transcripts (AS).We estimated that 32% of SS probes and 22% AS probes were rhythmic. This is a higher proportion of rhythmic probes than the usually found in similar experiments in other plant species. Orthologs and inparalogs of Arabidopsis thaliana, sugarcane, rice, maize and sorghum were grouped in ortholog clusters. When ortholog clusters were used to compare probes among different datasets, sugarcane also showed a higher proportion of rhythmic elements than the other species. Thus, it is possible that a higher proportion of transcripts are regulated by the sugarcane circadian clock. Thirty-six percent of the identified AS/SS pairs had significant correlated time courses and 64% had uncorrelated expression patterns. The clustering of transcripts with similar function, the anticipation of daily environmental changes and the temporal compartmentation of metabolic processes were some properties identified in the circadian sugarcane transcriptome. During the day, there was a dominance of transcripts associated with photosynthesis and carbohydrate metabolism, including sucrose and starch synthesis. During the night, there was dominance of transcripts associated with genetic processing, such as histone regulation and RNA polymerase, ribosome and protein synthesis. Finally, the circadian clock also regulated hormone signalling pathways: a large proportion of auxin and ABA signalling components were regulated by the circadian clock in an unusual biphasic distribution. PMID:23936527

Hotta, Carlos Takeshi; Nishiyama, Milton Yutaka; Souza, Glaucia Mendes

2013-01-01

258

Clock Genes may Influence Bipolar Disorder Susceptibility and Dysfunctional Circadian Rhythm  

PubMed Central

Several previous studies suggest that dysfunction of circadian rhythms may increase susceptibility to bipolar disorder (BP). We conducted an association study of five circadian genes (CRY2, PER1-3, and TIMELESS) in a family collection of 36 trios and 79 quads (Sample I), and 10 circadian genes (ARNTL, ARNTL2, BHLHB2, BHLHB3, CLOCK, CRY1, CSNK1D, CSNK1E, DBP, and NR1D1) in an extended family collection of 70 trios and 237 quads (Sample II), which includes the same 114 families but not necessarily the same individuals as Sample I. In Sample II, the Sibling-Transmission Disequilibrium Test (sib-tdt) analysis showed nominally significant association of BP with three SNPs within or near the CLOCK gene (rs534654, p = 0.0097; rs6850524, p = 0.012; rs4340844, p = 0.015). In addition, SNPs in the ARNTL2, CLOCK, DBP, and TIMELESS genes and haplotypes in the ARNTL, CLOCK, CSNK1E, and TIMELESS genes showed suggestive evidence of association with several circadian phenotypes identified in BP patients. However, none of these associations reached gene-wide or experiment-wide significance after correction for multiple-testing. A multi-locus interaction between rs6442925 in the 5? upstream of BHLHB2, rs1534891 in CSNK1E, and rs534654 near the 3? end of the CLOCK gene, however, is significantly associated with BP (p = 0.00000172). It remains significant after correcting for multiple testing using the False Discovery Rate method. Our results indicate an interaction between three circadian genes in susceptibility to bipolar disorder. PMID:18228528

Shi, Jiajun; Wittke-Thompson, Jacqueline K.; Badner, Judith A.; Hattori, Eiji; Potash, James B.; Willour, Virginia L; McMahon, Francis J.; Gershon, Elliot S.; Liu, Chunyu

2008-01-01

259

Properties of the Aplysia visual system: in vitro entrainment of the circadian rhythm and centrifugal regulation of the eye  

Microsoft Academic Search

1.Properties of the visual system of Aplysia californica were studied by recording optic nerve impulses extracellularly from isolated eyes in constant darkness.2.In vivo entrainment of the circadian rhythm of afferent optic nerve impulses by LD 12:12 cycles phase advanced 13 hours was essentially complete after only one exposure of the animal to this light cycle.3.The impulse rhythms of eyes exposed

Arnold Eskin

1971-01-01

260

Two-oscillator structure of the pacemaker controlling the circadian rhythm of N-acetyltransferase in the rat pineal gland  

Microsoft Academic Search

1.The organization of the pacemaker driving the circadian rhythm of N-acetyltransferase activity in the rat pineal gland was studied by observing changes of the rhythm caused by 1 min light pulses applied at night. These pulses proved to be effective phase-shifting signals.2.After 1 min light pulses applied in the first half of the night. N-acetyltransferase activity began to increase anew

Helena Illnerová; Ji?í Van??ek

1982-01-01

261

Influence of losartan intake on the circadian rhythm of melatonin secretion in humans.  

PubMed

It has been reported that losartan, an angiotensin II receptor blocker, alters the circadian rhythm of melatonin secretion and significantly reduces melatonin production. However, this finding has been confirmed at the animal experiment level only, and there are no reports of studies in humans. Therefore, we performed this study to confirm the reproducibility of the aforementioned findings of animal experiments in humans. Ten male subjects who were in good general health and free from any medical condition were recruited for this study. After a preliminary observation period of 7 days, the subjects received oral losartan treatment, 50 mg daily for 7 days. Blood samplings for measurement of the plasma melatonin concentrations were performed on day 7 of the preliminary observation period and day 7 of the losartan treatment period. The circadian rhythm of melatonin secretion after the 7-day treatment with losartan showed no significant difference from that recorded before the losartan administration. The significant decrease of the home blood pressure was observed on the afternoons. The blood samples showed significant decrease of the serum sodium and uric acid levels, along with a significant increase of the serum potassium level. The pharmacological actions of losartan at the ordinarily used clinical dose level were confirmed in humans, however, no significant inhibitory effect of the drug on melatonin secretion could be confirmed. These results are expected to be useful for guiding the proper use of angiotensin II receptor blockers. PMID:24716408

Arakawa, M; Uchida, N; Kanda, N; Kurosawa, Y; Odani, T; Kanmatsuse, K; Endo, M; Yamazaki, T; Hidaka, S

2014-03-01

262

Circadian rhythm and time of mating in Bactrocera cucurbitae (Diptera: Tephritidae) selected for age at reproduction.  

PubMed

Chrono-biological traits were changed by selecting for life-history traits via a genetic linkage controlling both time-related behavioural and life-history traits. Behavioural traits were compared between lines selected for young (Y-lines) and old (O-lines) age at reproduction in the melon fly, Bactrocera cucurbitae (Coquillett). Adults from O-lines, which survive longer than flies from Y-lines, mated later in the day and had a longer period of circadian rhythm in the locomotor activity than those from Y-lines. Flies from F(1) reciprocal crosses had an intermediate time of mating and periods of circadian rhythm between that of the parents, indicating a genetic basis to these traits. The presence of these behavioural differences across the selection lines indicates that chrono-biological traits exhibit correlated responses to selection on age at reproduction. The correlated responses in the behavioural traits to selection for life-history traits are discussed from two points of view: pleiotropy and inadvertent selection. PMID:11920139

Miyatake, Takahisa

2002-04-01

263

Light masking of circadian rhythms of heat production, heat loss, and body temperature in squirrel monkeys  

NASA Technical Reports Server (NTRS)

Whole body heat production (HP) and heat loss (HL) were examined to determine their relative contributions to light masking of the circadian rhythm in body temperature (Tb). Squirrel monkey metabolism (n = 6) was monitored by both indirect and direct calorimetry, with telemetered measurement of body temperature and activity. Feeding was also measured. Responses to an entraining light-dark (LD) cycle (LD 12:12) and a masking LD cycle (LD 2:2) were compared. HP and HL contributed to both the daily rhythm and the masking changes in Tb. All variables showed phase-dependent masking responses. Masking transients at L or D transitions were generally greater during subjective day; however, L masking resulted in sustained elevation of Tb, HP, and HL during subjective night. Parallel, apparently compensatory, changes of HL and HP suggest action by both the circadian timing system and light masking on Tb set point. Furthermore, transient HL increases during subjective night suggest that gain change may supplement set point regulation of Tb.

Robinson, E. L.; Fuller, C. A.

1999-01-01

264

Chronotype influences activity circadian rhythm and sleep: Differences in sleep quality between weekdays and weekend.  

PubMed

Several studies have shown the differences among chronotypes in the circadian rhythm of different physiological variables. Individuals show variation in their preference for the daily timing of activity; additionally, there is an association between chronotype and sleep duration/sleep complaints. Few studies have investigated sleep quality during the week days and weekends in relation to the circadian typology using self-assessment questionnaires or actigraphy. The purpose of this study was to use actigraphy to assess the relationship between the three chronotypes and the circadian rhythm of activity levels and to determine whether sleep parameters respond differently with respect to time (weekdays versus the weekend) in Morning-types (M-types), Neither-types (N-types) and Evening-types (E-types). The morningness-eveningness questionnaire (MEQ) was administered to 502 college students to determine their chronotypes. Fifty subjects (16?M-types, 15?N-types and 19?E-types) were recruited to undergo a 7-days monitoring period with an actigraph (Actiwacth® actometers, CNT, Cambridge, UK) to evaluate their sleep parameters and the circadian rhythm of their activity levels. To compare the amplitude and the acrophase among the three chronotypes, we used a one-way ANOVA followed by the Tukey-Kramer post-hoc test. To compare the Midline Estimating Statistic of Rhythm (MESOR) among the three chronotypes, we used a Kruskal-Wallis non-parametric test followed by pairwise comparisons that were performed using Dunn's procedure with a Bonferroni correction for multiple comparisons. The analysis of each sleep parameter was conducted using the mixed ANOVA procedure. The results showed that the chronotype was influenced by sex (?(2) with p?=?0.011) and the photoperiod at birth (?(2) with p?circadian rhythm of activity levels was influenced by the chronotype; second, the chronotype had a significant effect on sleep parameters: the E-types had a reduced sleep quality and quantity compared with the M- and N-types during weekdays, whereas the E-types reached the same levels as the other chronotypes during the weekends. These findings suggest that E-types accumulate a sleep deficit during weekdays due to social and academic commitments and that they recover from this deficit during "free days" on the weekend. PMID:25469597

Vitale, Jacopo A; Roveda, Eliana; Montaruli, Angela; Galasso, Letizia; Weydahl, Andi; Caumo, Andrea; Carandente, Franca

2014-12-01

265

Extensive and divergent circadian gene expression in liver and heart  

Microsoft Academic Search

Many mammalian peripheral tissues have circadian clocks; endogenous oscillators that generate transcriptional rhythms thought to be important for the daily timing of physiological processes. The extent of circadian gene regulation in peripheral tissues is unclear, and to what degree circadian regulation in different tissues involves common or specialized pathways is unknown. Here we report a comparative analysis of circadian gene

Kai-Florian Storch; Ovidiu Lipan; Igor Leykin; N. Viswanathan; Fred C. Davis; Wing H. Wong; Charles J. Weitz

2002-01-01

266

Simulated body temperature rhythms reveal the phase-shifting behavior and plasticity of mammalian circadian oscillators  

PubMed Central

The circadian pacemaker in the suprachiasmatic nuclei (SCN) of the hypothalamus maintains phase coherence in peripheral cells through metabolic, neuronal, and humoral signaling pathways. Here, we investigated the role of daily body temperature fluctuations as possible systemic cues in the resetting of peripheral oscillators. Using precise temperature devices in conjunction with real-time monitoring of the bioluminescence produced by circadian luciferase reporter genes, we showed that simulated body temperature cycles of mice and even humans, with daily temperature differences of only 3°C and 1°C, respectively, could gradually synchronize circadian gene expression in cultured fibroblasts. The time required for establishing the new steady-state phase depended on the reporter gene, but after a few days, the expression of each gene oscillated with a precise phase relative to that of the temperature cycles. Smooth temperature oscillations with a very small amplitude could synchronize fibroblast clocks over a wide temperature range, and such temperature rhythms were also capable of entraining gene expression cycles to periods significantly longer or shorter than 24 h. As revealed by genetic loss-of-function experiments, heat-shock factor 1 (HSF1), but not HSF2, was required for the efficient synchronization of fibroblast oscillators to simulated body temperature cycles. PMID:22379191

Saini, Camille; Morf, Jörg; Stratmann, Markus; Gos, Pascal; Schibler, Ueli

2012-01-01

267

Coordinated regulation of circadian rhythms and homeostasis by the suprachiasmatic nucleus  

PubMed Central

We have demonstrated that in rats activities of various enzymes related to gluconeogenesis and amino acid metabolism show circadian rhythms. Based on these results, we have explored the molecular mechanisms underlying circadian oscillation and phase response to light of the master clock located in the dorsomedial subdivision of the suprachiasmatic nucleus (SCN) and found various proteins closely related to phase response such as BIT/SHPS-1 and those of circadian oscillation, some of which are involved in protein-tyrosine phosphorylation. On the other hand, we have presented several lines of evidence that the ventrolateral subdivision of the SCN includes not only the control center of energy supply to the brain, but also that of homeostasis such as blood glucose, blood pressure, water balance, and body temperature. We have also shown that besides these functions, the latter subdivision is involved in the regulations of hormone secretions such as insulin, glucagon, corticosterone and vasopressin. It has been also shown by electrophysiological means that light exposure to rat eye enhances sympathetic nerve activity, whereas it depresses parasympathetic nerve activity. Thus, environmental light is implicated not only in the phase-shift through the retinohypthalamic tract (RHT), but also control of autonomic nerve activities through the RHT, It is also discussed in this review how the two divisions are interconnected and how environmental light is involved in this interconnection. PMID:20431263

Nakagawa, Hachiro; Okumura, Nobuaki

2010-01-01

268

ESR1 and ESR2 differentially regulate daily and circadian activity rhythms in female mice.  

PubMed

Estrogenic signaling shapes and modifies daily and circadian rhythms, the disruption of which has been implicated in psychiatric, neurologic, cardiovascular, and metabolic disease, among others. However, the activational mechanisms contributing to these effects remain poorly characterized. To determine the activational impact of estrogen on daily behavior patterns and differentiate between the contributions of the estrogen receptors ESR1 and ESR2, ovariectomized adult female mice were administered estradiol, the ESR1 agonist propylpyrazole triol, the ESR2 agonist diarylpropionitrile, or cholesterol (control). Animals were singly housed with running wheels in a 12-hour light, 12-hour dark cycle or total darkness. Estradiol increased total activity and amplitude, consolidated activity to the dark phase, delayed the time of peak activity (acrophase of wheel running), advanced the time of activity onset, and shortened the free running period (?), but did not alter the duration of activity (?). Importantly, activation of ESR1 or ESR2 differentially impacted daily and circadian rhythms. ESR1 stimulation increased total wheel running and amplitude and reduced the proportion of activity in the light vs the dark. Conversely, ESR2 activation modified the distribution of activity across the day, delayed acrophase of wheel running, and advanced the time of activity onset. Interestingly, ? was shortened by estradiol or either estrogen receptor agonist. Finally, estradiol-treated animals administered a light pulse in the early subjective night, but no other time, had an attenuated response compared with controls. This decreased phase response was mirrored by animals treated with diarylpropionitrile, but not propylpyrazole triol. To conclude, estradiol has strong activational effects on the temporal patterning and expression of daily and circadian behavior, and these effects are due to distinct mechanisms elicited by ESR1 and ESR2 activation. PMID:24735329

Royston, S E; Yasui, N; Kondilis, A G; Lord, S V; Katzenellenbogen, J A; Mahoney, M M

2014-07-01

269

The role of actigraphy in the study of sleep and circadian rhythms.  

PubMed

In summary, although actigraphy is not as accurate as PSG for determining some sleep measurements, studies are in general agreement that actigraphy, with its ability to record continuously for long time periods, is more reliable than sleep logs which rely on the patients' recall of how many times they woke up or how long they slept during the night and is more reliable than observations which only capture short time periods. Actigraphy can provide information obtainable in no other practical way. It can also have a role in the medical care of patients with sleep disorders. However, it should not be held to the same expectations as polysomnography. Actigraphy is one-dimensional, whereas polysomnography comprises at least 3 distinct types of data (EEG, EOG, EMG), which jointly determine whether a person is asleep or awake. It is therefore doubtful whether actigraphic data will ever be informationally equivalent to the PSG, although progress on hardware and data processing software is continuously being made. Although the 1995 practice parameters paper determined that actigraphy was not appropriate for the diagnosis of sleep disorders, more recent studies suggest that for some disorders, actigraphy may be more practical than PSG. While actigraphy is still not appropriate for the diagnosis of sleep disordered breathing or of periodic limb movements in sleep, it is highly appropriate for examining the sleep variability (i.e., night-to-night variability) in patients with insomnia. Actigraphy is also appropriate for the assessment of and stability of treatment effects of anything from hypnotic drugs to light treatment to CPAP, particularly if assessments are done before and after the start of treatment. A recent independent review of the actigraphy literature by Sadeh and Acebo reached many of these same conclusions. Some of the research studies failed to find relationships between sleep measures and health-related symptoms. The interpretation of these data is also not clear-cut. Is it that the actigraph is not reliable enough to the access the relationship between sleep changes and quality of life measures, or, is it that, in fact, there is no relationship between sleep in that population and quality of life measures? Other studies of sleep disordered breathing, where actigraphy was not used and was not an outcome measure also failed to find any relationship with quality of life. Is it then the actigraph that is not reliable or that the associations just do not exist? The one area where actigraphy can be used for clinical diagnosis is in the evaluation of circadian rhythm disorders. Actigraphy has been shown to be very good for identifying rhythms. Results of actigraphic recordings correlate well with measurements of melatonin and of core body temperature rhythms. Activity records also show sleep disturbance when sleep is attempted at an unfavorable phase of the circadian cycle. Actigraphy therefore would be particularly good for aiding in the diagnosis of delayed or advanced sleep phase syndrome, non-24-hour-sleep syndrome and in the evaluation of sleep disturbances in shift workers. It must be remembered, however, that overt rest-activity rhythms are susceptible to various masking effects, so they may not always show the underlying rhythm of the endogenous circadian pacemaker. In conclusion, the latest set of research articles suggest that in the clinical setting, actigraphy is reliable for evaluating sleep patterns in patients with insomnia, for studying the effect of treatments designed to improve sleep, in the diagnosis of circadian rhythm disorders (including shift work), and in evaluating sleep in individuals who are less likely to tolerate PSG, such as infants and demented elderly. While actigraphy has been used in research studies for many years, up to now, methodological issues had not been systematically addressed in clinical research and practice. Those issues have now been addressed and actigraphy may now be reaching the maturity needed for application in the clinical arena. PMID:12749557

Ancoli-Israel, Sonia; Cole, Roger; Alessi, Cathy; Chambers, Mark; Moorcroft, William; Pollak, Charles P

2003-05-01

270

Enhancement and Suppression of Ultradian and Circadian Rhythms across the Female Hamster Reproductive Cycle  

PubMed Central

The impact of ovarian hormones on hamster ultradian rhythms (URs) is unknown. We concurrently monitored URs and circadian rhythms (CRs) of home cage locomotor activity during the estrous cycle, pregnancy, and lactation of Syrian hamsters. URs with a mean period of 4–5 h were evident during the dark phase in more than 90% of females on days 1 and 2 of the estrous cycle but were significantly less prevalent on cycle days 3 and 4. The period of the UR did not vary as a function of estrous cycle stage, but at all stages, the UR period was longer in the dark than the light phase. The UR acrophase occurred significantly earlier on cycle day 4 than on days 1 and 2, and UR robustness and amplitude were reduced on days 3 and 4. Robustness, mesor, and amplitude of CRs were greater during cycle days 3 and 4; timing of the CR acrophase was delayed on day 4 relative to all other cycle days. Effects of the estrous cycle on URs were evident only during the dark phase. The proportion of hamsters displaying dark phase URs increased significantly during early and late gestation and decreased during lactation. Pregnancy significantly increased UR complexity, robustness, and amplitude. The emergence of URs over gestation was paralleled by decrements in the robustness and amplitude of CRs, which also were absent in a significant proportion of dams during lactation but re-emerged at weaning of litters. The changing endocrine profile of the estrous cycle, hormonal dynamics of pregnancy and lactation, and nursing demands placed on dams are each associated with alterations in the expression of ultradian and circadian locomotor rhythms. Diminution of CRs and augmentation of URs may afford greater behavioral flexibility during life stages when interactions with mates and offspring are less predictable. PMID:22653893

Prendergast, Brian J.; Beery, Annaliese K.; Paul, Matthew J.; Zucker, Irving

2013-01-01

271

Stochastic models of cellular circadian rhythms in plants help to understand the impact of noise on robustness and clock structure  

PubMed Central

Rhythmic behavior is essential for plants; for example, daily (circadian) rhythms control photosynthesis and seasonal rhythms regulate their life cycle. The core of the circadian clock is a genetic network that coordinates the expression of specific clock genes in a circadian rhythm reflecting the 24-h day/night cycle. Circadian clocks exhibit stochastic noise due to the low copy numbers of clock genes and the consequent cell-to-cell variation: this intrinsic noise plays a major role in circadian clocks by inducing more robust oscillatory behavior. Another source of noise is the environment, which causes variation in temperature and light intensity: this extrinsic noise is part of the requirement for the structural complexity of clock networks. Advances in experimental techniques now permit single-cell measurements and the development of single-cell models. Here we present some modeling studies showing the importance of considering both types of noise in understanding how plants adapt to regular and irregular light variations. Stochastic models have proven useful for understanding the effect of regular variations. By contrast, the impact of irregular variations and the interaction of different noise sources are less well studied. PMID:25374576

Guerriero, Maria L.; Akman, Ozgur E.; van Ooijen, Gerben

2014-01-01

272

Chronotype differences in circadian rhythms of temperature, melatonin, and sleepiness as measured in a modified constant routine protocol  

PubMed Central

Evening chronotypes typically have sleep patterns timed 2–3 hours later than morning chronotypes. Ambulatory studies have suggested that differences in the timing of underlying circadian rhythms as a cause of the sleep period differences. However, differences in endogenous circadian rhythms are best explored in laboratory protocols such as the constant routine. We used a 27-hour modified constant routine to measure the endogenous core temperature and melatonin circadian rhythms as well as subjective and objective sleepiness from hourly 15-minute sleep opportunities. Ten (8f) morning type individuals were compared with 12 (8f) evening types. All were young, healthy, good sleepers. The typical sleep onset, arising times, circadian phase markers for temperature and melatonin and objective sleepiness were all 2–3 hours later for the evening types than morning types. However, consistent with past studies the differences for the subjective sleepiness rhythms were much greater (5–9 hours). Therefore, the present study supports the important role of subjective alertness/sleepiness in determining the sleep period differences between morning and evening types and the possible vulnerability of evening types to delayed sleep phase disorder. PMID:23616692

Lack, Leon; Bailey, Michelle; Lovato, Nicole; Wright, Helen

2009-01-01

273

A Failure to Detect an Influence of Magnetic Fields on the Growth Rate and Circadian Rhythm of Neurospora crassa1  

PubMed Central

Low strength magnetic fields, 6.36 and 32.25 gauss, were found to have no effect, with one questionable exception, on the circadian rhythm and growth rate of Neurospora crassa. This was true whether the fields were continuous, pulsed 20 minutes daily, or on a 12: 12, on-off cycle. PMID:16658667

Bitz, D. Michael; Sargent, Malcolm L.

1974-01-01

274

No acute response of leptin to an oral fat load in obese patients and during circadian rhythm in healthy controls  

Microsoft Academic Search

This study was done to elucidate the relationship between postprandial leptin and obesity, and the possible influence of the circadian rhythm on the dynamic leptin response to an oral fat load (OFLT). In experiment 1, we measured the leptin and insulin responses to an oral fat load in 16 non-diabetic obese subjects and in 16 healthy controls, matched for age

B Guerci; Samy Hadjadj; Didier Quilliot; Olivier Ziegler; Pierre Drouin

2000-01-01

275

Dopamine receptor 1 neurons in the dorsal striatum regulate food anticipatory circadian activity rhythms in mice.  

PubMed

Daily rhythms of food anticipatory activity (FAA) are regulated independently of the suprachiasmatic nucleus, which mediates entrainment of rhythms to light, but the neural circuits that establish FAA remain elusive. In this study, we show that mice lacking the dopamine D1 receptor (D1R KO mice) manifest greatly reduced FAA, whereas mice lacking the dopamine D2 receptor have normal FAA. To determine where dopamine exerts its effect, we limited expression of dopamine signaling to the dorsal striatum of dopamine-deficient mice; these mice developed FAA. Within the dorsal striatum, the daily rhythm of clock gene period2 expression was markedly suppressed in D1R KO mice. Pharmacological activation of D1R at the same time daily was sufficient to establish anticipatory activity in wild-type mice. These results demonstrate that dopamine signaling to D1R-expressing neurons in the dorsal striatum plays an important role in manifestation of FAA, possibly by synchronizing circadian oscillators that modulate motivational processes and behavioral output. PMID:25217530

Gallardo, Christian M; Darvas, Martin; Oviatt, Mia; Chang, Chris H; Michalik, Mateusz; Huddy, Timothy F; Meyer, Emily E; Shuster, Scott A; Aguayo, Antonio; Hill, Elizabeth M; Kiani, Karun; Ikpeazu, Jonathan; Martinez, Johan S; Purpura, Mari; Smit, Andrea N; Patton, Danica F; Mistlberger, Ralph E; Palmiter, Richard D; Steele, Andrew D

2014-01-01

276

Hepatitis B virus X protein disrupts the balance of the expression of circadian rhythm genes in hepatocellular carcinoma  

PubMed Central

The human circadian rhythm is controlled by at least eight circadian clock genes and disruption of the circadian rhythm is associated with cancer development. The present study aims to elucidate the association between the expression of circadian clock genes and the development of hepatocellular carcinoma (HCC), and also to reveal whether the hepatitis B virus X protein (HBx) is the major regulator that contributes to the disturbance of circadian clock gene expression. The mRNA levels of circadian clock genes in 30 HCC and the paired peritumoral tissues were determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). A stable HBx-expressing cell line, Bel-7404-HBx, was established through transfection of HBx plasmids. The mRNA level of circadian clock genes was also detected by RT-qPCR in these cells. Compared with the paired peritumoral tissues, the mRNA levels of the Per1, Per2, Per3 and Cry2 genes in HCC tissue were significantly lower (P<0.05), while no significant difference was observed in the expression levels of CLOCK, BMAL1, Cry1 and casein kinase 1? (CK1?; P>0.05). Compared with Bel-7404 cells, the mRNA levels of the CLOCK, Per1 and Per2 genes in Bel-7404-HBx cells were significantly increased, while the mRNA levels of the BMAL1, Per3, Cry1, Cry2 and CKI? genes were decreased (P<0.05). Thus, the present study identified that disturbance of the expression of circadian clock genes is common in HCC. HBx disrupts the expression of circadian clock genes and may, therefore, induce the development of HCC. PMID:25360177

YANG, SHENG-LI; YU, CHAO; JIANG, JIAN-XIN; LIU, LI-PING; FANG, XIEFAN; WU, CHAO

2014-01-01

277

Lithium and genetic inhibition of GSK3? enhance the effect of methamphetamine on circadian rhythms in the mouse  

PubMed Central

Lithium, a drug commonly used to treat mood disorders, and the psychostimulant methamphetamine are both capable of altering circadian rhythmicity. Although the actions of lithium on the circadian system are thought to occur through inhibition of glycogen synthase kinase-3? (GSK3?), the mechanism by which methamphetamine alters circadian rhythms is unknown. We tested the effects of concurrent methamphetamine and lithium treatment on the circadian wheel-running behavior of mice. Methamphetamine alone lengthened both the active duration and the free-running period of locomotor activity in animals housed in constant conditions. Administering lithium enhanced the period-lengthening effects of methamphetamine in animals housed in constant darkness. This effect was even more pronounced when animals were housed in constant light. Lithium increased both methamphetamine intake and serum levels of methamphetamine, possibly contributing to the effects on circadian behavior. We also tested the effect of methamphetamine in mutant mice possessing only one allele for Gsk3?. These animals, when treated with methamphetamine, responded like wild-type mice treated with a combination of methamphetamine and lithium, displaying long, free-running rhythms. These data, together with many others in the literature, point to a complicated interaction between the circadian system and the development and possible treatment of psychopathologies such as bipolar disorder and drug addiction. PMID:19339873

Mohawk, Jennifer A.; Miranda-Anaya, Manuel; Tataroglu, Ozgur; Menaker, Michael

2010-01-01

278

Effects of Exposure to Intermittent versus Continuous Red Light on Human Circadian Rhythms, Melatonin Suppression, and Pupillary Constriction  

PubMed Central

Exposure to light is a major determinant of sleep timing and hormonal rhythms. The role of retinal cones in regulating circadian physiology remains unclear, however, as most studies have used light exposures that also activate the photopigment melanopsin. Here, we tested the hypothesis that exposure to alternating red light and darkness can enhance circadian resetting responses in humans by repeatedly activating cone photoreceptors. In a between-subjects study, healthy volunteers (n?=?24, 21–28 yr) lived individually in a laboratory for 6 consecutive days. Circadian rhythms of melatonin, cortisol, body temperature, and heart rate were assessed before and after exposure to 6 h of continuous red light (631 nm, 13 log photons cm?2 s?1), intermittent red light (1 min on/off), or bright white light (2,500 lux) near the onset of nocturnal melatonin secretion (n?=?8 in each group). Melatonin suppression and pupillary constriction were also assessed during light exposure. We found that circadian resetting responses were similar for exposure to continuous versus intermittent red light (P?=?0.69), with an average phase delay shift of almost an hour. Surprisingly, 2 subjects who were exposed to red light exhibited circadian responses similar in magnitude to those who were exposed to bright white light. Red light also elicited prolonged pupillary constriction, but did not suppress melatonin levels. These findings suggest that, for red light stimuli outside the range of sensitivity for melanopsin, cone photoreceptors can mediate circadian phase resetting of physiologic rhythms in some individuals. Our results also show that sensitivity thresholds differ across non-visual light responses, suggesting that cones may contribute differentially to circadian resetting, melatonin suppression, and the pupillary light reflex during exposure to continuous light. PMID:24797245

Ho Mien, Ivan; Chua, Eric Chern-Pin; Lau, Pauline; Tan, Luuan-Chin; Lee, Ivan Tian-Guang; Yeo, Sing-Chen; Tan, Sara Shuhui; Gooley, Joshua J.

2014-01-01

279

A circadian clock in Antarctic krill: an endogenous timing system governs metabolic output rhythms in the euphausid species Euphausia superba.  

PubMed

Antarctic krill, Euphausia superba, shapes the structure of the Southern Ocean ecosystem. Its central position in the food web, the ongoing environmental changes due to climatic warming, and increasing commercial interest on this species emphasize the urgency of understanding the adaptability of krill to its environment. Krill has evolved rhythmic physiological and behavioral functions which are synchronized with the daily and seasonal cycles of the complex Southern Ocean ecosystem. The mechanisms, however, leading to these rhythms are essentially unknown. Here, we show that krill possesses an endogenous circadian clock that governs metabolic and physiological output rhythms. We found that expression of the canonical clock gene cry2 was highly rhythmic both in a light-dark cycle and in constant darkness. We detected a remarkable short circadian period, which we interpret as a special feature of the krill's circadian clock that helps to entrain the circadian system to the extreme range of photoperiods krill is exposed to throughout the year. Furthermore, we found that important key metabolic enzymes of krill showed bimodal circadian oscillations (?9-12 h period) in transcript abundance and enzymatic activity. Oxygen consumption of krill showed ?9-12 h oscillations that correlated with the temporal activity profile of key enzymes of aerobic energy metabolism. Our results demonstrate the first report of an endogenous circadian timing system in Antarctic krill and its likely link to metabolic key processes. Krill's circadian clock may not only be critical for synchronization to the solar day but also for the control of seasonal events. This study provides a powerful basis for the investigation into the mechanisms of temporal synchronization in this marine key species and will also lead to the first comprehensive analyses of the circadian clock of a polar marine organism through the entire photoperiodic cycle. PMID:22022521

Teschke, Mathias; Wendt, Sabrina; Kawaguchi, So; Kramer, Achim; Meyer, Bettina

2011-01-01

280

Biochemical basis of circadian rhythms and diseases: With emphasis on post-traumatic stress disorder.  

PubMed

Circadian rhythms affect several processes in the body physiology. This commentary revisits the topic of 'metabolic basis of diseases' with a view to shed light on how cellular energy requirements feed-forward to a sequential signaling of hormonal response, blood glucose metabolism, antioxidant activities, and pathophysiology. Attempt is made to explain how diseases that may not appear to be closely related, such as bone metabolism and vasculopathy, have an increase in oxidative damage as a common underlying biochemistry. Importantly, this article identifies oxidative damage as an outcome of sleep disturbance and hypothesize that sleep complaint is not merely one of many resulting symptoms of PTSD, but a core feature that arise from trauma and gives rise to the stress biochemistry, which in turn manifests symptomatically. Further, we suggest that the current non-pharmacologic and pharmacologic therapeutic options attenuate oxidative stress. Implication for clinical diagnosis and evaluations is also suggested. PMID:21794988

Richards, R S; Nwose, E U; Bwititi, P

2011-10-01

281

Melatonin Regulates Aging and Neurodegeneration through Energy Metabolism, Epigenetics, Autophagy and Circadian Rhythm Pathways  

PubMed Central

Brain aging is linked to certain types of neurodegenerative diseases and identifying new therapeutic targets has become critical. Melatonin, a pineal hormone, associates with molecules and signaling pathways that sense and influence energy metabolism, autophagy, and circadian rhythms, including insulin-like growth factor 1 (IGF-1), Forkhead box O (FoxOs), sirtuins and mammalian target of rapamycin (mTOR) signaling pathways. This review summarizes the current understanding of how melatonin, together with molecular, cellular and systemic energy metabolisms, regulates epigenetic processes in the neurons. This information will lead to a greater understanding of molecular epigenetic aging of the brain and anti-aging mechanisms to increase lifespan under healthy conditions. PMID:25247581

Jenwitheesuk, Anorut; Nopparat, Chutikorn; Mukda, Sujira; Wongchitrat, Prapimpun; Govitrapong, Piyarat

2014-01-01

282

The effects of feedback lighting on the circadian drinking rhythm in the diurnal new world primate Saimiri sciureus  

NASA Technical Reports Server (NTRS)

Feedback lighting provides illumination primarily during the subjective night (i.e., the photosensitive portion of the circadian cycle) in response to a given behavior. This technique has previously been used to test the nonparametric model of entrainment in nocturnal rodents. In three species (Rattus norvegicus, Mesocricetus auratus, and Mus musculus), the free-running period of the locomotor activity rhythm was similar whether the animals were exposed to continuous light or discrete light pulses occurring essentially only during the subjective night (i.e., feedback lighting). In the current experiments, feedback lighting was presented to squirrel monkeys so that light fell predominantly during the subjective night. Feedback lighting was linked to the drinking behavior in this diurnal primate so that when the animal drank, the lights went out. Despite the seemingly adverse predicament, the monkeys maintained regular circadian drinking rhythms. Furthermore, just as the period of the free-running activity rhythms of nocturnal rodents exposed to continuous light or feedback lighting were similar, the period of the drinking rhythms of the squirrel monkeys in continuous light and feedback lighting were comparable (25.6 +/- 0.1 and 25.9 +/- 0.1 hours, respectively), despite a substantial decrease in the total amount of light exposure associated with feedback lighting. The free-running period of monkeys exposed to continuous dark (24.5 +/- 0.1 hours) was significantly shorter than either of the two lighting conditions (P < 0.001). The results presented for the drinking rhythm were confirmed by examination of the temperature and activity rhythms. Therefore, discrete light pulses given predominately during the subjective night are capable of simulating the effects of continuous light on the free-running period of the circadian rhythms of a diurnal primate. The response of squirrel monkeys to feedback lighting thus lends further support for the model and suggests that the major entrainment mechanisms are similar in nocturnal rodents and diurnal primates.

Ferraro, J. S.; Sulzman, F. M.

1988-01-01

283

Circadian rhythms in blood pressure in free-ranging three-toed sloths (Bradypus variegatus).  

PubMed

Blood pressure (BP) profiles were monitored in nine free-ranging sloths (Bradypus variegatus) by coupling one common carotid artery to a BP telemetry transmitter. Animals moved freely in an isolated and temperature-controlled room (24 degrees C) with 12/12-h artificial light-dark cycles and behaviors were observed during resting, eating and moving. Systolic (SBP) and diastolic (DBP) blood pressures were sampled for 1 min every 15 min for 24 h. BP rhythm over 24 h was analyzed by the cosinor method and the mesor, amplitude, acrophase and percent rhythm were calculated. A total of 764 measurements were made in the light cycle and 721 in the dark cycle. Twenty-four-hour values (mean +/- SD) were obtained for SBP (121 +/- 22 mmHg), DBP (86 +/- 17 mmHg), mean BP (MBP, 98 +/- 18 mmHg) and heart rate (73 +/- 16 bpm). The SBP, DBP and MBP were significantly higher (unpaired Student t-test) during the light period (125 +/- 21, 88 +/- 15 and 100 +/- 17 mmHg, respectively) than during the dark period (120 +/- 21, 85 +/- 17 and 97 +/- 17 mmHg, respectively) and the acrophase occurred between 16:00 and 17:45 h. This circadian variation is similar to that observed in cats, dogs and marmosets. The BP decreased during "behavioral sleep" (MBP down from 110 +/- 19 to 90 +/- 19 mmHg at 21:00 to 8:00 h). Both feeding and moving induced an increase in MBP (96 +/- 17 to 119 +/- 17 mmHg at 17:00 h and 97 +/- 19 to 105 +/- 12 mmHg at 15:00 h, respectively). The results show that conscious sloths present biphasic circadian fluctuations in BP levels, which are higher during the light period and are mainly synchronized with feeding. PMID:12563531

Duarte, D P F; Silva, V L; Jaguaribe, A M; Gilmore, D P; Da Costa, C P

2003-02-01

284

Stocking density affects circadian rhythms of locomotor activity in African catfish, Clarias gariepinus.  

PubMed

The effect of stocking density on the locomotor activity of African catfish C. gariepinus under different light regimes was investigated. C. gariepinus were stocked under different densities (1, 5, or 10 fish/tank), and their locomotor activity recorded under light-dark (LD), constant light (LL), constant darkness (DD), and LD-reversed (DL) regimens. Under the LD cycle, catfish showed a crepuscular activity pattern, irrespective of stocking density, with most of the daily activity concentrated around the light-onset and light-offset times. When fish were subjected to DD, all 4 tanks with medium (5 fish) and high (10 fish) stocking densities showed circadian rhythmicity, with an average period (?) of 23.3???0.5 and 24.6???0.5?h, respectively. In contrast, only 2 low (1 fish) density tanks showed free-running rhythms. Under LL, activity levels decreased significantly in comparison with levels observed under LD and DD. Moreover, fish of 1, 2, and 3 out of the 4 tanks with low, medium, and high densities, respectively, showed free-running rhythms under these conditions. When the photocycle was reversed (DL), fish of 3, 2, and 4 out of the 4 tanks with low, medium, and high stocking densities, respectively, showed gradual resynchronization to the new phase, and transient cycles of activity were observed. These results suggest that stocking density of fish affected the display of circadian rhythmicity and the intensity of activity levels. Thus, fish kept in higher densities showed more robust rhythmicity and higher levels of daily activity, indicating that social interactions may have an influence on behavioral patterns in the African catfish. PMID:21895490

Vera, Luisa Mar A; Al-Khamees, Sami; Herv, Migaud

2011-11-01

285

Circadian and circannual rhythms in the metabolism and ventilation of red-eared sliders (Trachemys scripta elegans).  

PubMed

Endogenous circadian and circannual rhythms may exist in the metabolism, ventilation, and breathing pattern of turtles that could further prolong dive times during daily and seasonal periods of reduced activity. To test this hypothesis, turtles were held under seasonal or constant environmental conditions over a 1-yr period, and in each season, V(O)(2) and respiratory variables were measured in all animals under both the prevailing seasonal conditions and the constant conditions for 24 h. Endogenous circadian and circannual rhythms in metabolism and ventilation occurred independent of ambient temperature, photoperiod, and activity, although long-term entrainment to daily and seasonal changes in temperature and photoperiod were required for them to be expressed. Metabolism and ventilation were always higher during the photophase, and the day-night difference was greater at any given temperature when the photoperiod was provided. When corrected for temperature, turtles had elevated metabolic and ventilation rates in the fall and spring (corresponding to the reproductive seasons) and suppressed metabolism and ventilation during winter. The strength of the circadian rhythm varied seasonally, with proportionately larger day-night differences in colder seasons. Daily and seasonal cycles in ventilation largely followed metabolism, although daily and seasonal changes did occur in the breathing pattern independent of levels of total ventilation. These endogenous circadian and circannual changes in metabolism, ventilation, and breathing pattern prolonged dive times at night and in winter and may serve to reduce the costs of breathing and transport and risk of predation. PMID:19358691

Reyes, Catalina; Milsom, William K

2010-01-01

286

Circadian clock-protein expression in cyanobacteria: rhythms and phase setting  

PubMed Central

The cyanobacterial gene cluster kaiABC encodes three essential circadian clock proteins: KaiA, KaiB and KaiC. The KaiB and KaiC protein levels are robustly rhythmical, whereas the KaiA protein abundance undergoes little if any circadian oscillation in constant light. The level of the KaiC protein is crucial for correct functioning of the clock because induction of the protein at phases when the protein level is normally low elicits phase resetting. Titration of the effects of the inducer upon phase resetting versus KaiC level shows a direct correlation between induction of the KaiC protein within the physiological range and significant phase shifting. The protein synthesis inhibitor chloramphenicol prevents the induction of KaiC and blocks phase shifting. When the metabolism is repressed by either translational inhibition or constant darkness, the rhythm of KaiC abundance persists; therefore, clock protein expression has a preferred status under a variety of conditions. These data indicate that rhythmic expression of KaiC appears to be a crucial component of clock precession in cyanobacteria. PMID:10880447

Xu, Yao; Mori, Tetsuya; Johnson, Carl Hirschie

2000-01-01

287

Food intake and circadian rhythms in shift workers with a high workload.  

PubMed

Shift work is associated with nutritional and health problems. In the present study, the food intake of garbage collectors of the city of Florianopolis (Brazil) was investigated using a dietary survey method based on meal recording during 24 h and adapted for the Brazilian food context. Three different shifts (morning, afternoon, and night) were compared (n=22 per shift). Age, body weight and body mass index (BMI) were similar for all groups. Daily energy expenditure was high in all three shifts, especially in morning shift workers. No difference in daily energy intake was found, in spite of differences in food choices and circadian ingestion rhythms. Energy intake was high and close to levels previously reported in athletes. Several factors not associated with shifts had significant impact on ingestion: hour of the day, time since the last meal, age, and BMI. Ingested foods were analyzed in groups based on nutrient content. Shifts significantly influenced intake of starches, alcoholic drinks, and sweets. In different periods of the day, food and nutrient intake were considerably affected by shifts. The analysis of circadian distribution of food choices and nutrient intake is important in shift workers, because total daily intake may not reveal shift-associated differences. PMID:12781167

de Assis, Maria Alice Altenburg; Kupek, Emil; Nahas, Markus Vinícius; Bellisle, France

2003-04-01

288

Serotonin increases the phase shift of the circadian locomotor activity rhythm in mice after dark pulses in constant light conditions.  

PubMed

Investigations on the effects of the 5-HT agonists and antagonists on the phase of the circadian locomotor activity rhythm of animals kept in constant light conditions (LL) are rare. Therefore the influence of R-(+)-OH-DPAT (5-HT1A receptors agonist) and metergoline (5-HT1/2/7 receptors antagonist) on the phase shift of the locomotor-activity rhythm alone and when combined with dark pulses in mice kept in LL are examined. The results indicate that 8-OH-DPAT administered independently at 12.00CT (Circadian Time) shifted the phase of the circadian rhythm and reinforced the effect of dark pulses on this parameter. 12.00CT was defined arbitrarily as the onset of locomotor activity in constant conditions. Metergoline diminished the phase shifts after dark pulses compared to 8-OH-DPAT. The influence of the serotonin agonist showed that serotonin can reinforce the phase shifting effect of the locomotor activity rhythm after dark pulses in LL condition. PMID:18274252

Bartoszewicz, Renata; Barbacka-Surowiak, Grazyna

2007-01-01

289

Acute dim light at night increases body mass, alters metabolism, and shifts core body temperature circadian rhythms.  

PubMed

The circadian system is primarily entrained by the ambient light environment and is fundamentally linked to metabolism. Mounting evidence suggests a causal relationship among aberrant light exposure, shift work, and metabolic disease. Previous research has demonstrated deleterious metabolic phenotypes elicited by chronic (>4 weeks) exposure to dim light at night (DLAN) (? 5 lux). However, the metabolic effects of short-term (<2 weeks) exposure to DLAN are unspecified. We hypothesized that metabolic alterations would arise in response to just 2 weeks of DLAN. Specifically, we predicted that mice exposed to dim light would gain more body mass, alter whole body metabolism, and display altered body temperature (Tb) and activity rhythms compared to mice maintained in dark nights. Our data largely support these predictions; DLAN mice gained significantly more mass, reduced whole body energy expenditure, increased carbohydrate over fat oxidation, and altered temperature circadian rhythms. Importantly, these alterations occurred despite similar activity locomotor levels (and rhythms) and total food intake between groups. Peripheral clocks are potently entrained by body temperature rhythms, and the deregulation of body temperature we observed may contribute to metabolic problems due to "internal desynchrony" between the central circadian oscillator and temperature sensitive peripheral clocks. We conclude that even relatively short-term exposure to low levels of nighttime light can influence metabolism to increase mass gain. PMID:24933325

Borniger, Jeremy C; Maurya, Santosh K; Periasamy, Muthu; Nelson, Randy J

2014-10-01

290

Phase advance of circadian rhythms in Smith-Magenis syndrome: A case study in an adult man.  

PubMed

Melatonin secretion is usually increased during the daytime and decreased at night in Smith-Magenis syndrome (SMS) and consequently is not a pertinent marker of the circadian phase of the clock in these cases. No data on temperature rhythm is available in SMS, another reliable marker of circadian clock activity. For this reason, we assessed the 24h profiles of core temperature, sleep-wake cycle, hormones (plasma cortisol and melatonin) and plasma and urine 6sulfatoxy-melatonin, the main hepatic melatonin metabolism in a 31-year-old man diagnosed with a SMS. All circadian rhythms, especially temperature rhythm showed a phase-advance, associated with reverse melatonin secretion. Plasma and urine 6sulfatoxy-melatonin profiles showed normal melatonin catabolism and confirmed the reversed melatonin secretion. Taking in consideration the reverse melatonin secretion and the phase-advanced temperature rhythm, which is driven by the suprachiasmatic nucleus, we hypothesize that the central clock is more sensitive to afternoon than to morning melatonin. This different responsiveness to melatonin according to the time of the day (i.e. chronaesthesia) corroborates the phase response curve of melatonin secretion to exogenous melatonin. PMID:25434872

Kocher, Laurence; Brun, Jocelyne; Devillard, Françoise; Azabou, Eric; Claustrat, Bruno

2015-01-12

291

Circadian rhythm sleep disorders in patients with multiple sclerosis and its association with fatigue: A case-control study  

PubMed Central

Background: Circadian rhythm sleep disorders are a presentation of sleep disorders in patients with multiple sclerosis (MS). This study aims to compare this problem in MS patients with healthy people and to determine its association with chronic fatigue in MS patients. Materials and Methods: A case-control study was performed on 120 MS patients and 60 healthy subjects matched for age and sex, in 2009 in MS Clinic Alzahra Hospital. Sleep quality, rhythm and fatigue severity were assessed using PSQI (Pittsburgh sleep quality index) and FSS (Fatigue severity Scale) questionnaires, respectively. Its reliability and validity has been confirmed in several studies (Cronbach's alpha = 0.83). This index has seven sections including patient's assessment of his/her sleep, sleep duration, efficacy of routine sleep, sleep disorders, use of hypnotic medication, and dysfunction in daily activities. Results: Circadian rhythm sleep disorder was more frequent in MS patients relative to healthy subjects (P: 0.002). It was higher in MS patients with severe fatigue relative to MS patients with mild fatigue (P: 0.05). Fatigue severity was 49.9 ± 8.2 and 22.5 ± 7.4 in the first and second group, respectively. PSQI index was 7.9 ± 4.5 in patients with severe fatigue and 5.9 ± 4.5 in patients with mild fatigue and 4.5 ± 2.4 in the control group (P: 0.0001). Conclusion: Circadian rhythm sleep disorders are more frequent in MS patients and those with fatigue. Recognition and management of circadian rhythm sleep disorders in MS patients, especially those with fatigue may be helpful in improving care of these patients. PMID:23961292

Najafi, Mohammad Reza; Toghianifar, Nafiseh; Etemadifar, Masoud; Haghighi, Sepehr; Maghzi, Amir Hadi; Akbari, Mojtaba

2013-01-01

292

Circadian rhythms in peak expiratory flow rate in workers exposed to cotton dust.  

PubMed Central

One hundred and sixty two people working in various departments of cotton spinning and weaving mills measured and recorded their own peak expiratory flow rate (PEFR) at two hourly intervals during Monday, Wednesday, and Thursday of the same work week, from waking in the morning throughout the day until going to bed and a last time the following morning after waking. The circadian rhythm in PEFR was computed by the Halberg program. The mean amplitude of the rhythm in the group was found to be 3.3% and the acrophase fell approximately in the middle of the waking hours. Older workers and those claiming to suffer from symptoms of chronic bronchitis were found to have an amplitude significantly higher (4.1% and 3.9% respectively) than their younger or symptom free counterparts (2.6% and 2.9% respectively; p less than 0.03). The amplitude of cardroom workers (2.4%), workers with byssinosis (2.7%), and those with much exposure to airborne cotton dust (3.3%) and bacteria (2.9%) tended to be lower than that of less exposed groups such as office staff (3.9%), though the difference was significant only in the case of cardroom workers (p less than 0.04). This may be due to airborne contaminants in the working environment. PMID:6495244

Cinkotai, F F; Sharpe, T C; Gibbs, A C

1984-01-01

293

Colorectal liver metastases with a disrupted circadian rhythm phase shift the peripheral clock in liver and kidney.  

PubMed

Circadian clock genes regulate 10-15% of the transcriptome, and might function as tumor suppressor genes. Relatively little is known about the circadian clock in tumors and its effect on surrounding healthy tissues. Therefore, we compared the 24-hr expression levels of key circadian clock genes in liver and kidney of healthy control mice with those of mice bearing C26 colorectal tumor metastases in the liver. Metastases were induced by injection of C26 colorectal carcinoma cells into the spleen. Subsequently, tumor, liver and kidney tissue was collected around the clock to compare circadian rhythmicity. Expression levels of five clock genes (Rev-Erb?, Per1, Per2, Bmal1 and Cry1) and three clock-controlled genes (CCGs; Dbp, p21 and Wee1) were determined by qRT-PCR. Liver and kidney tissue of healthy control mice showed normal 24-hr oscillations of all clock genes and CCGs, consistent with normal circadian rhythmicity. In colorectal liver metastases, however, 24-hr oscillations were completely absent for all clock genes and CCGs except Cry1. Liver and kidney tissue of tumor-bearing mice showed a shift in clock periodicity relative to control mice. In the liver we observed a phase advance, whereas in the kidney the phase was delayed. These data show that hepatic metastases of C26 colon carcinoma with a disrupted circadian rhythm phase shift liver and kidney tissue clocks, which strongly suggests a systemic effect on peripheral clocks. The possibility that tumors may modify peripheral clocks to escape from ordinary circadian rhythms and in this way contribute to fatigue and sleep disorders in cancer patients is discussed. PMID:25045881

Huisman, Sander A; Oklejewicz, Malgorzata; Ahmadi, Ali R; Tamanini, Filippo; Ijzermans, Jan N M; van der Horst, Gijsbertus T J; de Bruin, Ron W F

2015-03-01

294

Influence of head-down bed rest on the circadian rhythms of hormones and electrolytes involved in hydroelectrolytic regulation  

NASA Technical Reports Server (NTRS)

We investigated in six men the impact of a 17-day head-down bed rest (HDBR) on the circadian rhythms of the hormones and electrolytes involved in hydroelectrolytic regulation. This HDBR study was designed to mimic an actual spaceflight. Urine samples were collected at each voiding before, during and after HDBR. Urinary excretion of aldosterone, arginine vasopressin (AVP), cyclic guanosine monophosphate (cGMP), cortisol, electrolytes (Na+ and K+) and creatinine were determined. HDBR resulted in a significant reduction of body mass (P < 0.01) and of caloric intake [mean (SEM) 2,778 (37) kcal.24 h(-1) to 2,450 (36) kcal.24 h(-1), where 1 kcal.h(-1) = 1.163 J.s(-1); P< 0.01]. There was a significant increase in diastolic blood pressure [71.8 (0.7) mmHg vs 75.6 (0.91) mmHg], with no significant changes in either systolic blood pressure or heart rate. The nocturnal hormonal decrease of aldosterone was clearly evident only before and after HDBR, but the day/night difference did not appear during HDBR. The rhythm of K+ excretion was unchanged during HDBR, whereas for Na+ excretion, a large decrease was shown during the night as compared to the day. The circadian rhythm of cortisol persisted. These data suggest that exposure to a 17-day HDBR could induce an exaggeration of the amplitude of the Na+ rhythm and abolition of the aldosterone rhythm.

Millet, C.; Custaud, M. A.; Allevard, A. M.; Zaouali-Ajina, M.; Monk, T. H.; Arnaud, S. B.; Claustrat, B.; Gharib, C.; Gauquelin-Koch, G.

2001-01-01

295

Circadian temperature and melatonin rhythms, sleep, and neurobehavioral function in humans living on a 20-h day  

NASA Technical Reports Server (NTRS)

The interaction of homeostatic and circadian processes in the regulation of waking neurobehavioral functions and sleep was studied in six healthy young subjects. Subjects were scheduled to 15-24 repetitions of a 20-h rest/activity cycle, resulting in desynchrony between the sleep-wake cycle and the circadian rhythms of body temperature and melatonin. The circadian components of cognitive throughput, short-term memory, alertness, psychomotor vigilance, and sleep disruption were at peak levels near the temperature maximum, shortly before melatonin secretion onset. These measures exhibited their circadian nadir at or shortly after the temperature minimum, which in turn was shortly after the melatonin maximum. Neurobehavioral measures showed impairment toward the end of the 13-h 20-min scheduled wake episodes. This wake-dependent deterioration of neurobehavioral functions can be offset by the circadian drive for wakefulness, which peaks in the latter half of the habitual waking day during entrainment. The data demonstrate the exquisite sensitivity of many neurobehavioral functions to circadian phase and the accumulation of homeostatic drive for sleep.

Wyatt, J. K.; Ritz-De Cecco, A.; Czeisler, C. A.; Dijk, D. J.

1999-01-01

296

The effects on human sleep and circadian rhythms of 17 days of continuous bedrest in the absence of daylight  

NASA Technical Reports Server (NTRS)

As part of a larger bedrest study involving various life science experiments, a study was conducted on the effects of 17 days of continuous bedrest and elimination of daylight on circadian rectal temperature rhythms, mood, alertness, and sleep (objective and diary) in eight healthy middle-aged men. Sleep was timed from 2300 to 0700 hours throughout. Three 72-hour measurement blocks were compared: ambulatory prebedrest, early bedrest (days 5-7), and late bedrest (days 15-17). Temperature rhythms showed reduced amplitude and later phases resulting from the bedrest conditions. This was associated with longer nocturnal sleep onset latencies and poorer subjectively rated sleep but with no reliable changes in any of the other sleep parameters. Daily changes in posture and/or exposure to daylight appear to be important determinants of a properly entrained circadian system.

Monk, T. H.; Buysse, D. J.; Billy, B. D.; Kennedy, K. S.; Kupfer, D. J.

1997-01-01

297

Absence of apparent circadian rhythms of gonadotropins and free alpha-subunit in postmenopausal women: evidence for distinct regulation relative to other hormonal rhythms.  

PubMed

Aging is associated with a decrease in gonadotropin levels in postmenopausal women (PMW) and is also associated with alterations in a number of circadian rhythms. The goals of this study were to determine the presence of circadian rhythms of gonadotropins and glycoprotein free alpha-subunit (FAS) in young and old PMW. Healthy, euthyroid PMW, ages 45 to 55 years (n = 11) and 70 to 80 years (n = 11), were admitted in the morning to start a 24-h constant routine of light, temperature, position, and activity. Subjects remained awake and semirecumbent for the duration of the study and were fed hourly snacks, and activity was monitored continuously. Blood was sampled every 5 min for two 8-h periods corresponding to the estimated acrophase and nadir of the temperature rhythm. Luteinizing hormone (LH) and FAS were measured in all samples and follicle-stimulating hormone (FSH), thyroid-stimulating hormone (TSH), and cortisol in 20-min serum pools. Mean LH (p < 0.001), FSH (p < 0.002), and FAS (p < 0.002) were lower in older compared with younger PMW. Day/night differences in cortisol and TSH (p < 0.001) were present in all subjects. However, there were no day/night differences in LH in younger or older PMW or in FSH in younger or older PMW. There were no day/night differences in mean FAS in younger or older PMW or in FAS pulse frequency or amplitude. Thus, in controlled studies in which differences in cortisol and TSH were demonstrated, there were no day/night differences in LH, FSH, or FAS in PMW. These studies suggest that despite evidence of intact circadian rhythms of cortisol and TSH, gonadotropin secretion does not appear to follow a circadian pattern in PMW. Thus, the age-related decline in gonadotropin secretion in PMW is not associated with a dampening of circadian rhythmicity. The absence of day/night differences in FAS suggests that GnRH plays a more prominent role in FAS regulation than does thyrotropin-releasing hormone in PMW. PMID:16461985

Lavoie, Helene B; Marsh, Erica E; Hall, Janet E

2006-02-01

298

Health Impact of Fasting in Saudi Arabia during Ramadan: Association with Disturbed Circadian Rhythm and Metabolic and Sleeping Patterns  

PubMed Central

Background Muslims go through strict Ramadan fasting from dawn till sunset for one month yearly. These practices are associated with disturbed feeding and sleep patterns. We recently demonstrated that, during Ramadan, circadian cortisol rhythm of Saudis is abolished, exposing these subjects to continuously increased cortisol levels. Hypothesis Secretory patterns of other hormones and metabolic parameters associated with cortisol, and insulin resistance, might be affected during Ramadan. Protocol Ramadan practitioners (18 males, 5 females; mean age ±SEM?=?23.16±1.2 years) were evaluated before and two weeks into Ramadan. Blood was collected for measurements of endocrine and metabolic parameters at 9 am (±1 hour) and again twelve hours later. Results In Ramadan, glucose concentration was kept within normal range, with a significant increase in the morning. Mean morning concentration of leptin was significantly higher than pre-Ramadan values (p?=?0.001), in contrast to that of adiponectin, which was significantly lower (p<0.001). These changes were associated with increased insulin resistance in morning and evening. Concentrations of hsCRP were lower during Ramadan than those during regular living conditions, however, normal circadian fluctuation was abolished (p?=?0.49). Even though means of liver enzymes, total bilirubin, total protein and albumin were all decreased during Ramadan, statistically lower means were only noted for GGT, total protein, and albumin (p?=?0.018, 0.002 and 0.001 respectively). Discussion Saudi Ramadan practitioners have altered adipokine patterns, typical of insulin resistance. The noted decreases of hsCRP, liver enzymes, total protein, and albumin, are most likely a result of fasting, while loss of circadian rhythmicity of hsCRP is probably due to loss of circadian cortisol rhythm. Conclusions Modern Ramadan practices in Saudi Arabia, which are associated with evening hypercortisolism, are also characterized by altered adipokines patterns, and an abolished hsCRP circadian rhythm, all likely to increase cardiometabolic risk. PMID:24810091

Ajabnoor, Ghada M.; Bahijri, Suhad; Borai, Anwar; Abdulkhaliq, Altaf A.; Al-Aama, Jumana Y.; Chrousos, George P.

2014-01-01

299

Effects of bright light on cognitive and sleep-wake (circadian) rhythm disturbances in Alzheimer-type dementia  

Microsoft Academic Search

Twenty-seven patients with Alzheimer-type dementia (ATD) were treated with bright light therapy in the morning for four consecutive weeks. The cognitive state of each patient was evalu- ated with the Mini-Mental-State Examination (MMSE) and circadian rhythm with actigram before and after therapy for all of the patients and those of two groups divided by the severity criteria of the Clinical

Hiroshi Yamadera; Takao Ito; Hideaki Suzuki; Kentaro Asayama; Ritsuko Ito; Shunkichi Endo

2000-01-01

300

Effects of season and external testosterone on the freerunning circadian activity rhythm of european starlings ( Sturnus vulgaris )  

Microsoft Academic Search

1.Results obtained from activity recordings of birds living under natural photoperiodic conditions have suggested the hypothesis that the daily activity-time (a) and the period (t) of the circadian locomotor activity rhythm are affected not only by external variables but also by internal changes in the hormonal balance related to the annual cycle of reproduction.2.To test this hypothesis, in experiment 1,

Eberhard Gwinner

1975-01-01

301

Targeted Destruction of Photosensitive Retinal Ganglion Cells with a Saporin Conjugate Alters the Effects of Light on Mouse Circadian Rhythms  

Microsoft Academic Search

Non-image related responses to light, such as the synchronization of circadian rhythms to the day\\/night cycle, are mediated by classical rod\\/cone photoreceptors and by a small subset of retinal ganglion cells that are intrinsically photosensitive, expressing the photopigment, melanopsin. This raises the possibility that the melanopsin cells may be serving as a conduit for photic information detected by the rods

Didem Göz; Keith Studholme; Douglas A. Lappi; Mark D. Rollag; Ignacio Provencio; Lawrence P. Morin; Ernest Greene

2008-01-01

302

Circadian behavioral and melatonin rhythms in the European starling under light–dark cycles with steadily changing periods: Evidence for close mutual coupling?  

Microsoft Academic Search

In European starlings exposed to constant conditions, circadian rhythms in locomotion and feeding can occasionally exhibit complete dissociation from each other. Whether such occasional dissociation between two behavioral rhythms reflects on the strength of the mutual coupling of their internal oscillators has not been investigated. To examine this, as well as to elucidate the role of melatonin in this system,

Vinod Kumar; Thomas J. Van't Hof; Eberhard Gwinner

2007-01-01

303

The REV-ERBs and RORs: molecular links between circadian rhythms and lipid homeostasis  

PubMed Central

Research efforts spanning the past two decades have established a clear link between nuclear receptor function, regulation of the circadian clock and lipid homeostasis. As such, this family of receptors represents an important area of research. Recent advances in the field have identified two nuclear receptor subfamilies, the REV-ERBs and the ‘retinoic acid receptor-related orphan receptors’ (RORs), as critical regulators of the circadian clock with significant roles in lipid homeostasis. In this review, the latest information garnered from cutting-edge research on these two nuclear receptor subfamilies will be discussed. Through direct targeting of the REV-ERBs and RORs with synthetic ligands, generation of novel tools aimed at characterizing their function in vivo have been developed, which may lead to novel therapeutics for the treatment of metabolic disorders. PMID:21526899

Solt, Laura A; Kojetin, Douglas J; Burris, Thomas P

2011-01-01

304

Characterization of a circadian rhythm mutant identified in a genetic screen in Neurospora crassa  

E-print Network

Most organisms display daily rhythms in biochemical, physiological, and behavioral events. Examples of these rhythms include photosynthesis in plants and sleep/wake cycles in birds and mammals. These daily rhythms are controlled by an internal...

Keasler, Victor Vasco

2013-02-22

305

Development of respiratory rhythm generation in ectothermic vertebrates.  

PubMed

Compared with birds and mammals, very little is known about the development and regulation of respiratory rhythm generation in ectothermic vertebrates. The development and regulation of respiratory rhythm generation in ectothermic vertebrates (fish, amphibians and reptiles) should provide insight into the evolution of these mechanisms. One useful model for examining the development of respiratory rhythm generation in ectothermic vertebrates has emerged from studies with the North American bullfrog (Rana catesbeiana). A major advantage of bullfrogs as a comparative model for respiratory rhythm generation is that respiratory output may be measured at all stages of development, both in vivo and in vitro. An emerging view of recent studies in developing bullfrogs is that many of the mechanisms of respiratory rhythm generation are very similar to those seen in birds and mammals. The overall conclusion from these studies is that respiratory rhythm generation during development may be highly conserved during evolution. The development of respiratory rhythm generation in mammals may, therefore, reflect the antecedent mechanisms seen in ectothermic vertebrates. The main focus of this brief review is to discuss recent data on the development of respiratory rhythm generation in ectothermic vertebrates, with particular emphasis on the North American bullfrog (R. catesbeiana) as a model. PMID:15914099

Hedrick, Michael S

2005-11-15

306

Cetuximab and cancers of the head and neck: tapping the circadian rhythm.  

PubMed

Proteins in tissue obtained from human skin and oral mucosa have shown a significant circadian rhythm, with the peak expression of p27 at 6:00 AM (early G1-phase marker), p53 at 10:50 AM (late G1-phase marker) and cyclin-E at 2:50 PM (S-phase marker). Patients irradiated in late afternoon/evening have shown a higher grade of mucositis and dermatitis. Studies evaluating the effect of EGFR blockade on cell cycle progression in several human cell types, including A431 squamous epithelial carcinoma cells, suggest that cetuximab leads to cell cycle arrest in G1 phase. On concurrent administration with radiation, mucositis and dermatitis are its main side-effects. So we can hypothesize that cetuximab administration after 11:00 AM would decrease these toxicities. In addition, its administration prior to late afternoon/evening (3:00 PM) can further reduce the radiation associated mucositis and dermatitis due to the occurrence of S-phase during this time and thus increase the therapeutic benefit. PMID:21616603

Shukla, Pragya; Gupta, Deepak; Munshi, Anusheel; Agarwal, J P

2011-09-01

307

The circatidal rhythm persists without the optic lobe in the mangrove cricket Apteronemobius asahinai.  

PubMed

Whether the circatidal rhythm is generated by a machinery common to the circadian clock is one of the important and interesting questions in chronobiology. The mangrove cricket Apteronemobius asahinai shows a circatidal rhythm generating active and inactive phases and a circadian rhythm modifying the circatidal rhythm by inhibiting activity during the subjective day simultaneously. In the previous study, RNA interference of the circadian clock gene period disrupted the circadian rhythm but not the circatidal rhythm, suggesting a difference in molecular mechanisms between the circatidal and circadian rhythms. In the present study, to compare the neural mechanisms of these 2 rhythms, we observed locomotor activity in the mangrove cricket after surgical removal of the optic lobe, which has been shown to be the locus of the circadian clock in other crickets. We also noted the pigment-dispersing factor immunoreactive neurons (PDF-IRNs) in the optic lobe, because PDF is a key output molecule in the circadian clock system in some insects. The results showed that the circadian modulation was disrupted after the removal of the optic lobes but that the circatidal rhythm was maintained with no remarkable changes in its free-running period. Even in crickets in which some PDF-immunoreactive somata remained after removal of the optic lobe, the circadian rhythm was completely disrupted. The remnants of PDF-IRNs were not correlated to the occurrence and free-running period of the circatidal rhythm. These results indicate that the principal circatidal clock is located in a region(s) different from the optic lobe, whereas the circadian clock is located in the optic lobe, as in other crickets, and PDF-IRNs are not important for circatidal rhythm. Therefore, it is suggested that the circatidal rhythm of A. asahinai is driven by a neural basis different from that driving the circadian rhythm. PMID:24492880

Takekata, Hiroki; Numata, Hideharu; Shiga, Sakiko

2014-02-01

308

Circadian Rhythm of Outside-Nest Activity in Wild (WWCPS), Albino and Pigmented Laboratory Rats  

PubMed Central

The domestication process of the laboratory rat has been going on for several hundred generations in stable environmental conditions, which may have affected their physiological and behavioural functions, including their circadian system. Rats tested in our ethological experiments were laboratory-bred wild Norway rats (WWCPS), two strains of pigmented laboratory rats (Brown Norway and Long Evans), and two strains of albino rats (Sprague-Dawley and Wistar). Rats were placed in purpose-built enclosures and their cycle of activity (time spent actively outside the nest) has been studied for one week in standard light conditions and for the next one in round-the-clock darkness. The analysis of circadian pattern of outside-nest activity revealed differences between wild, pigmented laboratory, and albino laboratory strains. During daytime, albino rats showed lower activity than pigmented rats, greater decrease in activity when the light was turned on and greater increase in activity when the light was switched off, than pigmented rats. Moreover albino rats presented higher activity during the night than wild rats. The magnitude of the change in activity between daytime and nighttime was also more pronounced in albino rats. Additionaly, they slept outside the nest more often during the night than during the day. These results can be interpreted in accordance with the proposition that intense light is an aversive stimulus for albino rats, due to lack of pigment in their iris and choroid, which reduces their ability to adapt to light. Pigmented laboratory rats were more active during lights on, not only in comparison to the albino, but also to the wild rats. Since the difference seems to be independent of light intensity, it is likely to be a result of the domestication process. Cosinor analysis revealed a high rhythmicity of circadian cycles in all groups. PMID:23762462

Stryjek, Rafa?; Modli?ska, Klaudia; Turlejski, Krzysztof; Pisula, Wojciech

2013-01-01

309

Human ApoE ?4 Alters Circadian Rhythm Activity, IL-1?, and GFAP in CRND8 Mice.  

PubMed

Disruptions to daily living, inflammation, and astrogliosis are characteristics of Alzheimer's disease. Thus, circadian rhythms, nest construction, IL-1? and TNF-?, and glial fibrillary acidic protein (GFAP) were examined in a mouse model developed to model late-onset Alzheimer's disease-the most common form of the disease. Mice carrying both the mutated human A?PP transgene found in the CRND8 mouse and the human apolipoprotein E ?4 allele (CRND8/E4) were compared with CRND8 mice and wildtype (WT) mice. Circadian rhythms were evaluated by wheel-running behavior. Activity of daily living was measured by nest construction. This study then examined mRNA levels of the inflammatory cytokines IL-1? and TNF-? as well as protein levels of GFAP. Behavioral outcomes were then correlated with cytokines and GFAP. Compared to WT controls, both CRND8 and CRND8/E4 mice showed significantly more frequent, but shorter, bouts of activity. In the three groups, the CRND8/E4 mice had intermediate disruptions in circadian rhythms. Both CRND8/E4 mice and CRND8 mice showed significant impairments in nesting behavior compared to WTs. While CRND8 mice expressed significantly increased IL-1? and GFAP expression compared to WT controls, CRND8/E4 mice expressed intermediate IL-1? and GFAP levels. Significant correlations between IL-1?, GFAP, and behavior were observed. These data are congruent with other studies showing that human ApoE ?4 is protective early in life in transgenic mice modeling Alzheimer's disease. PMID:25159669

Graybeal, John J; Bozzelli, P Lorenzo; Graybeal, Lacey L; Groeber, Caitlin M; McKnight, Patrick E; Cox, Daniel N; Flinn, Jane M

2015-01-01

310

Behavioral characterization and modulation of circadian rhythms by light and melatonin in C3H/HeN mice homozygous for the RORbeta knockout.  

PubMed

This study reports for the first time the effects of retinoid-related orphan receptors [RORbeta; receptor gene deletion RORbeta(C3H)(-/-)] in C3H/HeN mice on behavioral and circadian phenotypes. Pineal melatonin levels showed a robust diurnal rhythm with high levels at night in wild-type (+/+), heterozygous (+/-), and knockout (-/-) mice. The RORbeta(C3H)(-/-) mice displayed motor ("duck gait," hind paw clasping reflex) and olfactory deficits, and reduced anxiety and learned helplessness-related behaviors. Circadian rhythms of wheel-running activity in all genotypes showed entrainment to the light-dark (LD) cycle, and free running in constant dark, with RORbeta(C3H)(-/-) mice showing a significant increase in circadian period (tau). Melatonin administration (90 microg/mouse sc for 3 days) at circadian time (CT) 10 induced phase advances, while exposure to a light pulse (300 lux) at CT 14 induced phase delays of circadian activity rhythms of the same magnitude in all genotypes. In RORbeta(C3H)(-/-) mice a light pulse at CT 22 elicited a larger phase advance in activity rhythms and a slower rate of reentrainment after a 6-h advance in the LD cycle compared with (+/+) mice. Yet, the rate of reentrainment was significantly advanced by melatonin administration at the new dark onset in both (+/+) and (-/-) mice. We conclude that the RORbeta nuclear receptor is not involved in either the rhythmic production of pineal melatonin or in mediating phase shifts of circadian rhythms by melatonin, but it may regulate clock responses to photic stimuli at certain time domains. PMID:17303680

Masana, Monica I; Sumaya, Isabel C; Becker-Andre, Michael; Dubocovich, Margarita L

2007-06-01

311

Mutational Analysis of the Drosophila Miniature-Dusky (M-Dy) Locus: Effects on Cell Size and Circadian Rhythms  

PubMed Central

A mutational analysis has been performed to explore the function of the Drosophila melanogaster miniature-dusky (m-dy) locus. Mutations at this locus affect wing development, fertility and behavior. The genetic characterization of 13 different mutations suggests that m and dy variants are alleles of a single complex gene. All of these mutations alter wing size, apparently by reducing the volume of individual epidermal cells of the developing wing. In m mutants, epidermal cell boundaries persist in the mature wing, whereas they normally degenerate 1-2 hr after eclosion in wild-type or dy flies. This has permitted the direct visualization of cell size differences among several m mutants. Mutations at the m-dy locus also affect behavioral processes. Three out of nine dy alleles (dy(n1), dy(n3) and dy(n4)) lengthen the circadian period of the activity and eclosion rhythms by approximately 1.5 hr. In contrast, m mutants have normal circadian periods, but an abnormally large percentage of individuals express aperiodic bouts of activity. These behavior genetic studies also indicate that an existing ``rhythm'' mutation known as Andante is an allele of the m-dy locus. The differential effects of certain m-dy mutations on wing and behavioral phenotypes suggest that separable domains of function exist within this locus. PMID:1908397

Newby, L. M.; White, L.; DiBartolomeis, S. M.; Walker, B. J.; Dowse, H. B.; Ringo, J. M.; Khuda, N.; Jackson, F. R.

1991-01-01

312

Circadian rhythms and different photoresponses of Clock gene transcription in the rat suprachiasmatic nucleus and pineal gland.  

PubMed

The aim of this study was to observe and compare the endogenous circadian rhythm and photoresponse of Clock gene transcription in the suprachiasmatic nucleus (SCN) and pineal gland (PG) of rats. With free access to food and water in special darkrooms, Sprague-Dawley rats were housed under the light regime of constant darkness (DD) for 8 weeks (n=36) or 12 hour-light: 12 hour-dark cycle (LD) for 4 weeks (n=36), respectively. Then, their SCN and PG were dissected out every 4 h in a circadian day, 6 rats at each time (n=6). All animal treatments and sampling during the dark phases were conducted under red dim light (<0.1 lux). The total RNA was extracted from each sample and the semi-quantitative RT-PCR was used to determine the temporal mRNA changes of Clock gene in the SCN and PG at different circadian times (CT) or zeitgeber times (ZT). The grayness ratio of Clock/H3.3 bands was served as the relative estimation of Clock gene expression. The experimental data were analyzed by the Cosine method and the Clock Lab software to fit original results measured at 6 time points and to simulate a circadian rhythmic curve which was then examined for statistical difference by the amplitude F test. The main results are as follows: (1) The mRNA levels of Clock gene in the SCN under DD regime displayed the circadian oscillation (P<0.05). The endogenous rhythmic profiles of Clock gene transcription in the PG were similar to those in the SCN (P>0.05) throughout the day with the peak at the subjective night (CT15 in the SCN or CT18 in the PG) and the trough during the subjective day (CT3 in the SCN or CT6 in the PG). (2) Clock gene transcription in the SCN under LD cycle also showed the circadian oscillation (P<0.05), and the rhythmic profile was anti-phasic to that under DD condition (P<0.05). The amplitude and the mRNA level at the peak of Clock gene transcription in the SCN under LD were significantly increased compared with that under DD (P<0.05), while the value of corresponding rhythmic parameters in the PG under LD were remarkably decreased (P<0.05). (3) Under LD cycle, the circadian profiles of Clock gene transcription induced by light in the PG were quite different from those in the SCN (P<0.05). Their Clock transcription rhythms were anti-phasic, i.e., showing peaks at the light phase ZT10 in the SCN or at the dark time ZT17 in the PG and troughs during the dark time ZT22 in the SCN or during the light phase ZT5 in the PG. The findings of the present study indicate a synchronous endogenous nature of the Clock gene circadian transcriptions in the SCN and PG, and different roles of light regime in modulating the circadian transcriptions of Clock gene in these two central nuclei. PMID:16906337

Wang, Guo-Qing; Fu, Chun-Ling; Li, Jian-Xiang; Du, Yu-Zhen; Tong, Jian

2006-08-25

313

Expression profiling of skeletal muscle following acute and chronic ?2-adrenergic stimulation: implications for hypertrophy, metabolism and circadian rhythm  

PubMed Central

Background Systemic administration of ?-adrenoceptor (?-AR) agonists has been found to induce skeletal muscle hypertrophy and significant metabolic changes. In the context of energy homeostasis, the importance of ?-AR signaling has been highlighted by the inability of ?1-3-AR-deficient mice to regulate energy expenditure and susceptibility to diet induced obesity. However, the molecular pathways and gene expression changes that initiate and maintain these phenotypic modulations are poorly understood. Therefore, the aim of this study was to identify differential changes in gene expression in murine skeletal muscle associated with systemic (acute and chronic) administration of the ?2-AR agonist formoterol. Results Skeletal muscle gene expression (from murine tibialis anterior) was profiled at both 1 and 4 hours following systemic administration of the ?2-AR agonist formoterol, using Illumina 46K mouse BeadArrays. Illumina expression profiling revealed significant expression changes in genes associated with skeletal muscle hypertrophy, myoblast differentiation, metabolism, circadian rhythm, transcription, histones, and oxidative stress. Differentially expressed genes relevant to the regulation of muscle mass and metabolism (in the context of the hypertrophic phenotype) were further validated by quantitative RT-PCR to examine gene expression in response to both acute (1-24 h) and chronic administration (1-28 days) of formoterol at multiple timepoints. In terms of skeletal muscle hypertrophy, attenuation of myostatin signaling (including differential expression of myostatin, activin receptor IIB, phospho-Smad3 etc) was observed following acute and chronic administration of formoterol. Acute (but not chronic) administration of formoterol also significantly induced the expression of genes involved in oxidative metabolism, including hexokinase 2, sorbin and SH3 domain containing 1, and uncoupling protein 3. Interestingly, formoterol administration also appeared to influence some genes associated with the peripheral regulation of circadian rhythm (including nuclear factor interleukin 3 regulated, D site albumin promoter binding protein, and cryptochrome 2). Conclusion This is the first study to utilize gene expression profiling to examine global gene expression in response to acute ?2-AR agonist treatment of skeletal muscle. In summary, systemic administration of a ?2-AR agonist had a profound effect on global gene expression in skeletal muscle. In terms of hypertrophy, ?2-AR agonist treatment altered the expression of several genes associated with myostatin signaling, a previously unreported effect of ?-AR signaling in skeletal muscle. This study also demonstrates a ?2-AR agonist regulation of circadian rhythm genes, indicating crosstalk between ?-AR signaling and circadian cycling in skeletal muscle. Gene expression alterations discovered in this study provides insight into many of the underlying changes in gene expression that mediate ?-AR induced skeletal muscle hypertrophy and altered metabolism. PMID:19772666

Pearen, Michael A; Ryall, James G; Lynch, Gordon S; Muscat, George EO

2009-01-01

314

Explaining the sawtooth: latitudinal periodicity in a circadian gene correlates with shifts in generation number.  

PubMed

Many temperate insects take advantage of longer growing seasons at lower latitudes by increasing their generation number or voltinism. In some insects, development time abruptly decreases when additional generations are fit into the season. Consequently, latitudinal 'sawtooth' clines associated with shifts in voltinism are seen for phenotypes correlated with development time, like body size. However, latitudinal variation in voltinism has not been linked to genetic variation at specific loci. Here, we show a pattern in allele frequency among voltinism ecotypes of the European corn borer moth (Ostrinia nubilalis) that is reminiscent of a sawtooth cline. We characterized 145 autosomal and sex-linked SNPs and found that period, a circadian gene that is genetically linked to a major QTL determining variation in post-diapause development time, shows cyclical variation between voltinism ecotypes. Allele frequencies at an unlinked circadian clock gene cryptochrome1 were correlated with period. These results suggest that selection on development time to 'fit' complete life cycles into a latitudinally varying growing season produces oscillations in alleles associated with voltinism, primarily through changes at loci underlying the duration of transitions between diapause and other life history phases. Correlations among clock loci suggest possible coupling between the circadian clock and the circannual rhythms for synchronizing seasonal life history. We anticipate that latitudinal oscillations in allele frequency will represent signatures of adaptation to seasonal environments in other insects and may be critical to understanding the ecological and evolutionary consequences of variable environments, including response to global climate change. PMID:25430782

Levy, R C; Kozak, G M; Wadsworth, C B; Coates, B S; Dopman, E B

2015-01-01

315

Abnormal circadian rhythm and cortisol excretion in autistic children: a clinical study  

PubMed Central

Aim To determine the circadian rhythm alteration of cortisol excretion and the level of corticosteroids in children with different grades of autism severity. Methods The study included 45 children with different grades of autism severity (low [LFA], medium [MFA], and high functioning autism [HFA]), 15 in each group, and 45 age/sex-matched children with typical development. The urinary levels of free cortisol (at three phases of 24-hour cycle), corticosteroids, vanilylmandelic acid, and 5-hydroxyindole acetic acid were determined. Results Alteration in the pattern of cortisol excretion (Phases I, II, and III) was observed in children with LFA (Phase I: 43.8?±?4.43 vs 74.30±8.62, P?=?0.000; Phase II: 21.1±2.87 vs 62±7.68, P?

Lakshmi Priya, Malarveni Damodaran; Geetha, Arumugam; Suganya, Vijayashankar; Sujatha, Sridharan

2013-01-01

316

Leptin-sensitive neurons in the arcuate nucleus integrate activity and temperature circadian rhythms and anticipatory responses to food restriction  

PubMed Central

Previously, we investigated the role of neuropeptide Y and leptin-sensitive networks in the mediobasal hypothalamus in sleep and feeding and found profound homeostatic and circadian deficits with an intact suprachiasmatic nucleus. We propose that the arcuate nuclei (Arc) are required for the integration of homeostatic circadian systems, including temperature and activity. We tested this hypothesis using saporin toxin conjugated to leptin (Lep-SAP) injected into Arc in rats. Lep-SAP rats became obese and hyperphagic and progressed through a dynamic phase to a static phase of growth. Circadian rhythms were examined over 49 days during the static phase. Rats were maintained on a 12:12-h light-dark (LD) schedule for 13 days and, thereafter, maintained in continuous dark (DD). After the first 13 days of DD, food was restricted to 4 h/day for 10 days. We found that the activity of Lep-SAP rats was arrhythmic in DD, but that food anticipatory activity was, nevertheless, entrainable to the restricted feeding schedule, and the entrained rhythm persisted during the subsequent 3-day fast in DD. Thus, for activity, the circuitry for the light-entrainable oscillator, but not for the food-entrainable oscillator, was disabled by the Arc lesion. In contrast, temperature remained rhythmic in DD in the Lep-SAP rats and did not entrain to restricted feeding. We conclude that the leptin-sensitive network that includes the Arc is required for entrainment of activity by photic cues and entrainment of temperature by food, but is not required for entrainment of activity by food or temperature by photic cues. PMID:23986359

Li, Ai-Jun; Dinh, Thu T.; Jansen, Heiko T.; Ritter, Sue

2013-01-01

317

Targeted Destruction of Photosensitive Retinal Ganglion Cells with a Saporin Conjugate Alters the Effects of Light on Mouse Circadian Rhythms  

PubMed Central

Non-image related responses to light, such as the synchronization of circadian rhythms to the day/night cycle, are mediated by classical rod/cone photoreceptors and by a small subset of retinal ganglion cells that are intrinsically photosensitive, expressing the photopigment, melanopsin. This raises the possibility that the melanopsin cells may be serving as a conduit for photic information detected by the rods and/or cones. To test this idea, we developed a specific immunotoxin consisting of an anti-melanopsin antibody conjugated to the ribosome-inactivating protein, saporin. Intravitreal injection of this immunotoxin results in targeted destruction of melanopsin cells. We find that the specific loss of these cells in the adult mouse retina alters the effects of light on circadian rhythms. In particular, the photosensitivity of the circadian system is significantly attenuated. A subset of animals becomes non-responsive to the light/dark cycle, a characteristic previously observed in mice lacking rods, cones, and functional melanopsin cells. Mice lacking melanopsin cells are also unable to show light induced negative masking, a phenomenon known to be mediated by such cells, but both visual cliff and light/dark preference responses are normal. These data suggest that cells containing melanopsin do indeed function as a conduit for rod and/or cone information for certain non-image forming visual responses. Furthermore, we have developed a technique to specifically ablate melanopsin cells in the fully developed adult retina. This approach can be applied to any species subject to the existence of appropriate anti-melanopsin antibodies. PMID:18773079

Göz, Didem; Studholme, Keith; Lappi, Douglas A.; Rollag, Mark D.; Provencio, Ignacio; Morin, Lawrence P.

2008-01-01

318

Circadian expression patterns of vrille in peripheral tissues of mutants in Drosophila melanogaster  

Microsoft Academic Search

The circadian clock of Drosophila (fruit fly) has been extensively studied as a model system in molecular chronobiology. In Drosophila melanogaster, several clock genes are necessary for the generation and regulation of overt rhythms. Among these, vrille (vri) is a clock gene as well as a clock-controlled gene and its oscillation is essential for circadian rhythms at both molecular and

R. Sivaperumal; P. Subramanian; K. V. Pugalendi

2009-01-01

319

Phase shifting the circadian rhythm of neuronal activity in the isolated Aplysia eye with puromycin and cycloheximide. Electrophysiological and biochemical studies  

Microsoft Academic Search

A B S X R A c x The effects of pulse application of puromycin (PURO) or cyclohexi- mide (CHX) were tested on the circadian rhythm (CR) of spontaneous compound action potential (CAP) activity in the isolated Aplysia eye. CAP activity was recorded from the optic nerve in constant darkness at 15°C. PURO pulses (6, 12 h; 12-134\\/~g\\/ ml) and

BARRY S. ROTHMAN; FELIX STRUMWASSER

1976-01-01

320

Circadian rhythms of gene expression of lipid metabolism in Gilthead Sea bream liver: synchronisation to light and feeding time.  

PubMed

This research aimed at investigating circadian rhythm expression of key genes involved in lipid metabolism in the liver of a teleost fish (Sparus aurata), and their synchronisation to different light-dark (L-D) and feeding cycles. To this end, 90 gilthead sea bream were kept in 12:12?h (light:dark, LD, lights on at ZT0) and fed a single daily meal at mid-light (ML?=?ZT6), mid-darkness (MD?=?ZT18) and randomly (RD) at a 1.5% body weight ration. A total of 18 tanks were used, six tanks per feeding treatment with five fishes per tank; locomotor activity was recorded in each tank. After 25 days of synchronisation to these feeding regimes, fishes were fasted for one day and liver samples were taken every 4 hours during a 24?h cycle (ZT2, 6, 10, 14, 18 and 22) and stored at -80?°C until analysis. To determine whether the rhythm expression presented an endogenous control, another experiment was performed using 30 fish kept in complete darkness and fed randomly (DD/RD). Samples were taken following the same procedure as above. The results revealed that all genes investigated exhibited well defined daily rhythms. The lipolysis-related and fatty acid turnover genes (hormone-sensitive lipase (hsl) and peroxisome proliferator-activated receptor-? (ppar?)) exhibited a nocturnal achrophase (Ø?=?ZT18:03-19:21); lipoprotein lipase (lpl) also showed the same nocturnal achrophase (Ø?=?ZT20:04-21:36). In contrast, lipogenesis-related gene, fatty acid synthase (fas), and of fatty acid turnover, cyclooxygenase (cox-2), showed a diurnal rhythm (Ø?=?ZT2:27-8:09); while ppar? was nocturnal (Ø?=?ZT16:16-18:05). Curiously, feeding time had little influence on the phase of these daily rhythms, since all feeding groups displayed similar achrophases. Furthermore, under constant conditions ppar? and hsl showed circadian rhythmicity. These findings suggest that lipid utilisation in the liver is rhythmic and strongly synchronised to the LD cycle, regardless of feeding time, which should be taken into consideration when investigating fish nutrition and the design of feeding protocols. PMID:24517141

Paredes, Juan Fernando; Vera, Luisa María; Martinez-Lopez, F Javier; Navarro, Isabel; Sánchez Vázquez, F Javier

2014-06-01

321

Silencing the circadian clock gene Clock using RNAi reveals dissociation of the circatidal clock from the circadian clock in the mangrove cricket.  

PubMed

Whether a clock that generates a circatidal rhythm shares the same elements as the circadian clock is not fully understood. The mangrove cricket, Apteronemobius asahinai, shows simultaneously two endogenous rhythms in its locomotor activity; the circatidal rhythm generates active and inactive phases, and the circadian rhythm modifies activity levels by suppressing the activity during subjective day. In the present study, we silenced Clock (Clk), a master gene of the circadian clock, in A. asahinai using RNAi to investigate the link between the circatidal and circadian clocks. The abundance of Clk mRNA in the crickets injected with double-stranded RNA of Clk (dsClk) was reduced to a half of that in control crickets. dsClk injection also reduced mRNA abundance of another circadian clock gene period (per) and weakened diel oscillation in per mRNA expression. Examination of the locomotor rhythms under constant conditions revealed that the circadian modification was disrupted after silencing Clk expression, but the circatidal rhythm remained unaffected. There were no significant changes in the free-running period of the circatidal rhythm between the controls and the crickets injected with dsClk. Our results reveal that Clk is essential for the circadian clock, but is not required for the circatidal clock. From these results we propose that the circatidal rhythm of A. asahinai is driven by a clock, the molecular components of which are distinct from that of the circadian clock. PMID:24995838

Takekata, Hiroki; Numata, Hideharu; Shiga, Sakiko; Goto, Shin G

2014-09-01

322

Research on sleep, circadian rhythms and aging - Applications to manned spaceflight  

NASA Technical Reports Server (NTRS)

Disorders of sleep and circadian rhythmicity are characteristic of both advancing age and manned spaceflight. Sleep fragmentation, reduced nocturnal sleep tendency and sleep efficiency, reduced daytime alertness, and increased daytime napping are common to both of these conditions. Recent research on the pathophysiology and treatment of disrupted sleep in older people has led to a better understanding of how the human circadian pacemaker regulates the timing of the daily sleep-wake cycle and how it responds to the periodic changes in the light-dark cycle to which we are ordinarily exposed. These findings have led to new treatments for some of the sleep disorders common to older individuals, using carefully timed exposure to bright light and darkness to manipulate the phase and/or amplitude of the circadian timing system. These insights and treatment approaches have direct applications in the design of countermeasures allowing astronauts to overcome some of the challenges which manned spaceflight poses for the human circadian timing system. We have conducted an operational feasibility study on the use of scheduled exposure to bright light and darkness prior to launch in order to facilitate adaptation of the circadian system of a NASA Space Shuttle crew to the altered sleep-wake schedule required for their mission. The results of this study illustrate how an understanding of the properties of the human circadian timing system and the consequences of circadian disruption can be applied to manned spaceflight.

Czeisler, Charles A.; Chiasera, August J.; Duffy, Jeanne F.

1991-01-01

323

Effects of daily melatonin administration on circadian activity rhythms in the diurnal Indian palm squirrel (Funambulus pennanti).  

PubMed

Exogenous melatonin induces phase shifts in circadian rhythms according to a phase response curve in nocturnal rodents, several nonmammalian diurnal species, and humans. Daily administration of melatonin entrains rhythms within a narrow circadian window of sensitivity in these species. Entrainment to exogenous melatonin has not previously been demonstrated in a (nonhuman) diurnal mammal. The authors examined the effects of daily melatonin administration (via food) in the diurnal Indian palm squirrel, Funambulus pennanti. The effects of melatonin or vehicle were examined at two times of day: zeitgeber time 0 (ZT 0: light onset time) and ZT 12 (dark onset time). In addition to melatonin- and vehicle-treated squirrels, there was a third group of squirrels that received no treatment. Squirrels were held initially under 12:12 light-dark (LD) cycles, and melatonin (1 mg/kg) or vehicle was administered in food (a raisin) at either ZT 0 or ZT 12 for a total of 17 days. On the third day of treatment, constant lighting (LL) was imposed. Treatment continued at the same ZTs for a further 14 days. The number of days before free-running commenced under constant conditions was assessed for squirrels in each treatment group. Results showed that regardless of the ZT of administration, the number of days before free-running commenced was significantly greater in melatonin-treated squirrels than in vehicle-treated and untreated squirrels, and there was no difference between vehicle-treated and untreated squirrels. Although there was not a significant difference in the number of days before free-running commenced between the two times of administration, the results showed a trend for greater sensitivity to melatonin at ZT 12. This study has therefore demonstrated that the palm squirrel circadian system is entrainable to melatonin at both times of day tested, ZTs 0 and 12. This finding is in contrast to previous melatonin entrainment studies in other species, where entrainment generally occurred at only one phase, around circadian times 10 to 12. Interspecies differences in response to melatonin were discussed. PMID:9438882

Rajaratnam, S M; Redman, J R

1997-08-01

324

Sympathetic activation induces skeletal Fgf23 expression in a circadian rhythm-dependent manner.  

PubMed

The circadian clock network is well known to link food intake and metabolic outputs. Phosphorus is a pivotal nutritional factor involved in energy and skeletal metabolisms and possesses a circadian profile in the circulation; however, the precise mechanisms whereby phosphate metabolism is regulated by the circadian clock network remain largely unknown. Because sympathetic tone, which displays a circadian profile, is activated by food intake, we tested the hypothesis that phosphate metabolism was regulated by the circadian clock network through the modification of food intake-associated sympathetic activation. Skeletal Fgf23 expression showed higher expression during the dark phase (DP) associated with elevated circulating FGF23 levels and enhanced phosphate excretion in the urine. The peaks in skeletal Fgf23 expression and urine epinephrine levels, a marker for sympathetic tone, shifted from DP to the light phase (LP) when mice were fed during LP. Interestingly, ?-adrenergic agonist, isoproterenol (ISO), induced skeletal Fgf23 expression when administered at ZT12, but this was not observed in Bmal1-deficient mice. In vitro reporter assays revealed that ISO trans-activated Fgf23 promoter through a cAMP responsive element in osteoblastic UMR-106 cells. The mechanism of circadian regulation of Fgf23 induction by ISO in vivo was partly explained by the suppressive effect of Cryptochrome1 (Cry1) on ISO signaling. These results indicate that the regulation of skeletal Fgf23 expression by sympathetic activity is dependent on the circadian clock system and may shed light on new regulatory networks of FGF23 that could be important for understanding the physiology of phosphate metabolism. PMID:24302726

Kawai, Masanobu; Kinoshita, Saori; Shimba, Shigeki; Ozono, Keiichi; Michigami, Toshimi

2014-01-17

325

Sympathetic Activation Induces Skeletal Fgf23 Expression in a Circadian Rhythm-dependent Manner*  

PubMed Central

The circadian clock network is well known to link food intake and metabolic outputs. Phosphorus is a pivotal nutritional factor involved in energy and skeletal metabolisms and possesses a circadian profile in the circulation; however, the precise mechanisms whereby phosphate metabolism is regulated by the circadian clock network remain largely unknown. Because sympathetic tone, which displays a circadian profile, is activated by food intake, we tested the hypothesis that phosphate metabolism was regulated by the circadian clock network through the modification of food intake-associated sympathetic activation. Skeletal Fgf23 expression showed higher expression during the dark phase (DP) associated with elevated circulating FGF23 levels and enhanced phosphate excretion in the urine. The peaks in skeletal Fgf23 expression and urine epinephrine levels, a marker for sympathetic tone, shifted from DP to the light phase (LP) when mice were fed during LP. Interestingly, ?-adrenergic agonist, isoproterenol (ISO), induced skeletal Fgf23 expression when administered at ZT12, but this was not observed in Bmal1-deficient mice. In vitro reporter assays revealed that ISO trans-activated Fgf23 promoter through a cAMP responsive element in osteoblastic UMR-106 cells. The mechanism of circadian regulation of Fgf23 induction by ISO in vivo was partly explained by the suppressive effect of Cryptochrome1 (Cry1) on ISO signaling. These results indicate that the regulation of skeletal Fgf23 expression by sympathetic activity is dependent on the circadian clock system and may shed light on new regulatory networks of FGF23 that could be important for understanding the physiology of phosphate metabolism. PMID:24302726

Kawai, Masanobu; Kinoshita, Saori; Shimba, Shigeki; Ozono, Keiichi; Michigami, Toshimi

2014-01-01

326

Sleep-Wake Circadian Activity Rhythm Parameters and Fatigue in Oncology Patients Prior to the Initiation of Radiation Therapy  

PubMed Central

Background Little is known about the relationships between sleep parameters and fatigue in patients at the initiation of radiation therapy (RT). Objectives In a sample of patients at the initiation of RT, to describe values for nocturnal sleep/rest, daytime wake/activity, and circadian activity rhythm parameters measured using actigraphy and to evaluate the relationships between these objective parameters and subjective ratings of sleep disturbance and fatigue severity. Methods Patients (n=185) with breast, prostate, lung, or brain cancer completed self-report measures for sleep disturbance (i.e., Pittsburgh Sleep Quality Index, General Sleep Disturbance Scale) and fatigue (Lee Fatigue Scale) and wore wrist actigraphs for a total of 48 hours prior to beginning RT. Actigraphy data were analyzed using the Cole-Kripke algorithm. Spearman rank correlations were calculated between variables. Results Approximately 30% to 50% of patients experienced sleep disturbance depending on whether clinically significant cutoffs for the subjective or objective measures were used to calculate occurrence rates. In addition, these patients reported moderate levels of fatigue. Only a limited number of significant correlations were found between the subjective and objective measures of sleep disturbance. Significant positive correlations were found between the subjective, but not the objective measures of sleep disturbance and fatigue. Conclusions A significant percentage of oncology patients experience significant disturbances in sleep-wake circadian activity rhythms at the initiation of RT. The disturbances occur in both sleep initiation and sleep maintenance. Implications for Practice Patients need to be assessed at the initiation of RT for sleep disturbance and appropriate treatment initiated. PMID:21252646

Miaskowski, Christine; Lee, Kathryn; Dunn, Laura; Dodd, Marylin; Aouizerat, Bradley E.; West, Claudia; Paul, Steven M.; Cooper, Bruce; Wara, William; Swift, Patrick

2010-01-01

327

Circadian rhythms in blood pressure regulation and optimization of hypertension treatment with ACE inhibitor and ARB medications.  

PubMed

Specific features of the 24 h-blood pressure (BP) pattern are linked to the progressive injury of target tissues and risk of cardiac and cerebrovascular events. Studies have consistently shown an association between blunted asleep BP decline and increased incidence of fatal and nonfatal cardiovascular events. Thus, there is growing interest in how to achieve better BP control during nighttime sleep in addition to during daytime activity, according to the particular requirements of each hypertension patient. One approach takes into consideration the endogenous circadian rhythm-determinants of the 24-h BP pattern, especially, the prominent day-night variation of the renin-angiotensin-aldosterone system, which activates during nighttime sleep. A series of clinical studies have demonstrated a different effect of the angiotensin-converting enzyme (ACE) inhibitors benazepril, captopril, enalapril, lisinopril, perindopril, quinapril, ramipril, spirapril, and trandolapril when routinely ingested in the morning vs. the evening. In most cases, the evening schedule exerts a more marked effect on the asleep than awake BP means. Similarly, a once-daily evening, in comparison to morning, ingestion schedule of the angiotensin receptor blockers (ARBs) irbesartan, olmesartan, telmisartan, and valsartan exerts greater therapeutic effect on asleep BP, plus significant increase in the sleep-time relative BP decline, with normalization of the circadian BP profile toward a more dipping pattern, independent of drug terminal half-life. Chronotherapy, the timing of treatment to body rhythms, is a cost-effective means of both individualizing and optimizing the treatment of hypertension through normalization of the 24-h BP level and profile, and it may constitute an effective option to reduce cardiovascular risk. PMID:20930708

Hermida, Ramón C; Ayala, Diana E; Fernández, José R; Portaluppi, Francesco; Fabbian, Fabio; Smolensky, Michael H

2011-04-01

328

Socially synchronized circadian oscillators  

PubMed Central

Daily rhythms of physiology and behaviour are governed by an endogenous timekeeping mechanism (a circadian ‘clock’). The alternation of environmental light and darkness synchronizes (entrains) these rhythms to the natural day–night cycle, and underlying mechanisms have been investigated using singly housed animals in the laboratory. But, most species ordinarily would not live out their lives in such seclusion; in their natural habitats, they interact with other individuals, and some live in colonies with highly developed social structures requiring temporal synchronization. Social cues may thus be critical to the adaptive function of the circadian system, but elucidating their role and the responsible mechanisms has proven elusive. Here, we highlight three model systems that are now being applied to understanding the biology of socially synchronized circadian oscillators: the fruitfly, with its powerful array of molecular genetic tools; the honeybee, with its complex natural society and clear division of labour; and, at a different level of biological organization, the rodent suprachiasmatic nucleus, site of the brain's circadian clock, with its network of mutually coupled single-cell oscillators. Analyses at the ‘group’ level of circadian organization will likely generate a more complex, but ultimately more comprehensive, view of clocks and rhythms and their contribution to fitness in nature. PMID:23825203

Bloch, Guy; Herzog, Erik D.; Levine, Joel D.; Schwartz, William J.

2013-01-01

329

Effects of circadian rhythm and cAMP on retinomotor movements in the green sunfish, Lepomis cyanellus.  

PubMed

The photoreceptors and retinal pigmented epithelium (RPE) of teleosts undergo diurnal changes in position in response to day/night changes in light conditions. These position changes, called retinomotor movements, may also persist under conditions of constant darkness. In this study, the authors have compared the retinomotor movements of rods, cones, and RPE under conditions of constant darkness and constant temperature in the green sunfish, Lepomis cyanellus . In this species, cones undergo circadian cycles of retinomotor movements in constant darkness but rods and RPE do not. Also cone contraction commences in early morning before the expected time of light onset, thus suggesting that circadian rhythms may play an important regulatory role in these cells even under cyclic light conditions. Since treatments that elevate cAMP previously have been shown to induce dark-adaptive retinomotor positions, the authors also have compared the effects of exogenous cAMP analogs on retinomotor positions of rods, cones, and RPE pigment in cultured green sunfish retinas. The authors found that concentrations of cAMP analogs required to produce extreme dark-adaptive retinomotor positions were at least fivefold higher for cones than for rods and RPE. PMID:6325366

Burnside, B; Ackland, N

1984-05-01

330

Genetic analysis of circadian and ultradian locomotor activity rhythms in laboratory rats  

Microsoft Academic Search

Obvious differences exist in the daily activity patterns of the LEW\\/Ztm and ACI\\/Ztm inbred strains of laboratory rats. The inbred strain ACI\\/Ztm shows a clear 24-h rhythm of locomotor activity. The activity pattern of the LEW\\/Ztm strain, however, is characterized by ultradian rhythms of 4- and 4.8-h periods. Genetic analysis of crosses between the two strains was used to examine

Franziska Wollnik; Klaus Gärtner; Dietmar Büttner

1987-01-01

331

[Circadian rhythm of ornithine decarboxylase and its endogenous high molecular weight inhibitor in rat pineal gland].  

PubMed

The biochemical mechanisms involved in circadian variations of the activity of ornithine decarboxylase (EC 4.1.1.17)--the rate-limiting enzyme of polyamine biosynthesis in rat pineal gland were studied. The enzyme was separated from its endogenous high molecular weight inhibitor by gel-filtration of the cytosol fraction from this organ through Sephadex G-100 in the presence of 250 mM NaCl. The inhibitor was similar in its molecular weight (30 000) and activity to ornithine decarboxylase inhibior from rat liver. The amount of the enzyme in the pineal gland undergoes much smaller circadian variations as compared to that of the inhibitor. It is concluded that the circadian variations of the ornithine decarboxylase activity in the pineal gland may be largely due to the changes in the enzyme/inhibitor ratio. PMID:497279

Iarygin, K N; Trushina, E D; Isachenkov, V A

1979-07-01

332

Genetic background influences age-related decline in visual and nonvisual retinal responses, circadian rhythms, and sleep?  

PubMed Central

The circadian system is entrained to the environmental light/dark cycle via retinal photoreceptors and regulates numerous aspects of physiology and behavior, including sleep. These processes are all key factors in healthy aging showing a gradual decline with age. Despite their importance, the exact mechanisms underlying this decline are yet to be fully understood. One of the most effective tools we have to understand the genetic factors underlying these processes are genetically inbred mouse strains. The most commonly used reference mouse strain is C57BL/6J, but recently, resources such as the International Knockout Mouse Consortium have started producing large numbers of mouse mutant lines on a pure genetic background, C57BL/6N. Considering the substantial genetic diversity between mouse strains we expect there to be phenotypic differences, including differential effects of aging, in these and other strains. Such differences need to be characterized not only to establish how different mouse strains may model the aging process but also to understand how genetic background might modify age-related phenotypes. To ascertain the effects of aging on sleep/wake behavior, circadian rhythms, and light input and whether these effects are mouse strain-dependent, we have screened C57BL/6J, C57BL/6N, C3H-HeH, and C3H-Pde6b+ mouse strains at 5 ages throughout their life span. Our data show that sleep, circadian, and light input parameters are all disrupted by the aging process. Moreover, we have cataloged a number of strain-specific aging effects, including the rate of cataract development, decline in the pupillary light response, and changes in sleep fragmentation and the proportion of time spent asleep. PMID:25179226

Banks, Gareth; Heise, Ines; Starbuck, Becky; Osborne, Tamzin; Wisby, Laura; Potter, Paul; Jackson, Ian J.; Foster, Russell G.; Peirson, Stuart N.; Nolan, Patrick M.

2015-01-01

333

A Role for CHH Methylation in the Parent-of-Origin Effect on Altered Circadian Rhythms and Biomass Heterosis in Arabidopsis Intraspecific Hybrids.  

PubMed

Hybrid plants and animals often show increased levels of growth and fitness, a phenomenon known as hybrid vigor or heterosis. Circadian rhythms optimize physiology and metabolism in plants and animals. In plant hybrids and polyploids, expression changes of the genes within the circadian regulatory network, such as CIRCADIAN CLOCK ASSOCIATED1 (CCA1), lead to heterosis. However, the relationship between allelic CCA1 expression and heterosis has remained elusive. Here, we show a parent-of-origin effect on altered circadian rhythms and heterosis in Arabidopsis thaliana F1 hybrids. This parent-of-origin effect on biomass heterosis correlates with altered CCA1 expression amplitudes, which are associated with methylation levels of CHH (where H = A, T, or C) sites in the promoter region. The direction of rhythmic expression and hybrid vigor is reversed in reciprocal F1 crosses involving mutants that are defective in the RNA-directed DNA methylation pathway (argonaute4 and nuclear RNA polymerase D1a) but not in the maintenance methylation pathway (methyltransferase1 and decrease in DNA methylation1). This parent-of-origin effect on circadian regulation and heterosis is established during early embryogenesis and maintained throughout growth and development. PMID:24894042

Ng, Danny W-K; Miller, Marisa; Yu, Helen H; Huang, Tien-Yu; Kim, Eun-Deok; Lu, Jie; Xie, Qiguang; McClung, C Robertson; Chen, Z Jeffrey

2014-06-01

334

A Role for CHH Methylation in the Parent-of-Origin Effect on Altered Circadian Rhythms and Biomass Heterosis in Arabidopsis Intraspecific Hybrids[W][OPEN  

PubMed Central

Hybrid plants and animals often show increased levels of growth and fitness, a phenomenon known as hybrid vigor or heterosis. Circadian rhythms optimize physiology and metabolism in plants and animals. In plant hybrids and polyploids, expression changes of the genes within the circadian regulatory network, such as CIRCADIAN CLOCK ASSOCIATED1 (CCA1), lead to heterosis. However, the relationship between allelic CCA1 expression and heterosis has remained elusive. Here, we show a parent-of-origin effect on altered circadian rhythms and heterosis in Arabidopsis thaliana F1 hybrids. This parent-of-origin effect on biomass heterosis correlates with altered CCA1 expression amplitudes, which are associated with methylation levels of CHH (where H = A, T, or C) sites in the promoter region. The direction of rhythmic expression and hybrid vigor is reversed in reciprocal F1 crosses involving mutants that are defective in the RNA-directed DNA methylation pathway (argonaute4 and nuclear RNA polymerase D1a) but not in the maintenance methylation pathway (methyltransferase1 and decrease in DNA methylation1). This parent-of-origin effect on circadian regulation and heterosis is established during early embryogenesis and maintained throughout growth and development. PMID:24894042

Ng, Danny W.-K.; Miller, Marisa; Yu, Helen H.; Huang, Tien-Yu; Kim, Eun-Deok; Lu, Jie; Xie, Qiguang; McClung, C. Robertson; Chen, Z. Jeffrey

2014-01-01

335

The association of quality of life with potentially remediable disruptions of circadian sleep/activity rhythms in patients with advanced lung cancer  

PubMed Central

Background Cancer patients routinely develop symptoms consistent with profound circadian disruption, which causes circadian disruption diminished quality of life. This study was initiated to determine the relationship between the severity of potentially remediable cancer-associated circadian disruption and quality of life among patients with advanced lung cancer. Methods We concurrently investigated the relationship between the circadian rhythms of 84 advanced lung cancer patients and their quality of life outcomes as measured by the EORTC QLQ C30 and Ferrans and Powers QLI. The robustness and stability of activity/sleep circadian daily rhythms were measured by actigraphy. Fifty three of the patients in the study were starting their definitive therapy following diagnosis and thirty one patients were beginning second-line therapy. Among the patients who failed prior therapy, the median time between completing definitive therapy and baseline actigraphy was 4.3 months, (interquartile range 2.1 to 9.8 months). Results We found that circadian disruption is universal and severe among these patients compared to non-cancer-bearing individuals. We found that each of these patient's EORTC QLQ C30 domain scores revealed a compromised capacity to perform the routine activities of daily life. The severity of several, but not all, EORTC QLQ C30 symptom items correlate strongly with the degree of individual circadian disruption. In addition, the scores of all four Ferrans/Powers QLI domains correlate strongly with the degree of circadian disruption. Although Ferrans/Powers QLI domain scores show that cancer and its treatment spared these patients' emotional and psychological health, the QLI Health/Function domain score revealed high levels of patients' dissatisfaction with their health which is much worse when circadian disruption is severe. Circadian disruption selectively affects specific Quality of Life domains, such as the Ferrans/Powers Health/Function domain, and not others, such as EORTC QLQ C30 Physical Domain. Conclusions These data suggest the testable possibility that behavioral, hormonal and/or light-based strategies to improve circadian organization may help patients suffering from advanced lung cancer to feel and function better. PMID:21605390

2011-01-01

336

Social Interactions and the Circadian Rhythm in Locomotor Activity in the Cockroach Leucophaea maderae  

PubMed Central

The role of social interactions in entrainment has not been extensively studied in the invertebrates. Leucophaea maderae is a gregarious species of cockroach that exhibits extensive social interactions. Social interactions associated with copulation between the sexes have been shown to be regulated by the circadian system. We show here that social interactions between males are also under circadian control. We examined the question of whether or not these rhythmic social contacts could function as zeitgebers capable of regulating circadian phase and period. Animals initially in phase that were housed as groups or pairs of single sex or mixed sex in constant darkness for 2–7 weeks were found to drift out of phase. Their behavior was not significantly different from individual animals maintained in isolation. Further, animals that were initially out of phase by 12 hours housed as groups or pairs were not significantly different in phase from animals that were isolated. The results show that the circadian clocks of cockroaches are remarkably insensitive to the extensive social interactions that occur between individuals. PMID:19360487

Knadler, Joseph J.; Page, Terry L.

2013-01-01

337

[Circadian rhythms and light responses of clock gene and arylalkylamine N-acetyltransferase gene expressions in the pineal gland of rats].  

PubMed

This study was to investigate the circadian rhythms and light responses of Clock gene and arylalkylamine N-acetyltransferase (NAT) gene expressions in the rat pineal gland under the 12 h-light : 12 h-dark cycle condition (LD) and constant darkness (DD). Sprague-Dawley rats housed under the light regime of LD (n=36) for 4 weeks and of DD (n=36) for 8 weeks were sampled for the pineal gland once a group (n=6) every 4 h in a circadian day. The total RNA was extracted from each sample and the semiquantitative reverse transcription polymerase chain reaction (RT-PCR) was used to determine the temporal changes in mRNA levels of Clock and NAT genes during different circadian times or zeitgeber times. The data were analysed by the cosine function software, Clock Lab software and the amplitude F test was used to reveal the circadian rhythm. The main results obtained are as follows. (1) In DD or LD condition, both of Clock and NAT genes mRNA levels in the pineal gland showed robust circadian oscillation (P< 0.05) with the peak at the subjective night or at night-time. (2) In comparison with DD regime, the amplitudes and the mRNA levels at peaks of Clock and NAT genes expressions in LD in the pineal gland were significantly reduced (P< 0.05). (3) In DD or LD condition, the circadian expressions of NAT gene were similar in pattern to those of Clock gene in the pineal gland (P> 0.05). These findings suggest that the expressions of Clock and NAT genes in the pineal gland not only show remarkably synchronous endogenous circadian rhythmic changes, but also response to the ambient light signal in a reduced manner. PMID:15719143

Wang, Guo-Qing; Du, Yu-Zhen; Tong, Jian

2005-02-25

338

Free Access to a Running-Wheel Advances the Phase of Behavioral and Physiological Circadian Rhythms and Peripheral Molecular Clocks in Mice  

PubMed Central

Behavioral and physiological circadian rhythms are controlled by endogenous oscillators in animals. Voluntary wheel-running in rodents is thought to be an appropriate model of aerobic exercise in humans. We evaluated the effects of chronic voluntary exercise on the circadian system by analyzing temporal profiles of feeding, core body temperature, plasma hormone concentrations and peripheral expression of clock and clock-controlled genes in mice housed under sedentary (SED) conditions or given free access to a running-wheel (RW) for four weeks. Voluntary wheel-running activity advanced the circadian phases of increases in body temperature, food intake and corticosterone secretion in the mice. The circadian expression of clock and clock-controlled genes was tissue- and gene-specifically affected in the RW mice. The temporal expression of E-box-dependent circadian clock genes such as Per1, Per2, Nr1d1 and Dbp were slightly, but significantly phase-advanced in the liver and white adipose tissue, but not in brown adipose tissue and skeletal muscle. Peak levels of Per1, Per2 and Nr1d1 expression were significantly increased in the skeletal muscle of RW mice. The circadian phase and levels of hepatic mRNA expression of the clock-controlled genes that are involved in cholesterol and fatty acid metabolism significantly differed between SED and RW mice. These findings indicated that endogenous clock-governed voluntary wheel-running activity provides feedback to the central circadian clock that systemically governs behavioral and physiological rhythms. PMID:25615603

Yasumoto, Yuki; Nakao, Reiko; Oishi, Katsutaka

2015-01-01

339

Dynamic capabilities to match multiple product generations and market rhythm  

Microsoft Academic Search

Purpose – The purpose of this paper is to provide greater insights to managers seeking to time properly the launches of innovative new products (NPs) across multiple generations. This paper aims to address the rhythm matching problem by developing a typology and a conceptual framework of the interaction between a firm's technological readiness to launch NPs and a market's receptivity

Scott G. Dacko; Ben S. Liu; D. Sudharshan; Olivier Furrer

2008-01-01

340

Melatonin phase-shifts human circadian rhythms with no evidence of changes in the duration of endogenous melatonin secretion or the 24-hour production of reproductive hormones.  

PubMed

The pineal hormone melatonin is a popular treatment for sleep and circadian rhythm disruption. Melatonin administered at optimal times of the day for treatment often results in a prolonged melatonin profile. In photoperiodic (day length-dependent) species, changes in melatonin profile duration influence the timing of seasonal rhythms. We investigated the effects of an artificially prolonged melatonin profile on endogenous melatonin and cortisol rhythms, wrist actigraphy, and reproductive hormones in humans. Eight healthy men took part in this double-blind, crossover study. Surge/sustained release melatonin (1.5 mg) or placebo was administered for 8 d at the beginning of a 16-h sleep opportunity (1600 h to 0800 h) in dim light. Compared with placebo, melatonin administration advanced the timing of endogenous melatonin and cortisol rhythms. Activity was reduced in the first half and increased in the second half of the sleep opportunity with melatonin; however, total activity during the sleep opportunities and wake episodes was not affected. Melatonin treatment did not affect the endogenous melatonin profile duration, pituitary/gonadal hormone levels (24-h), or sleepiness and mood levels on the subsequent day. In the short term, suitably timed sustained-release melatonin phase-shifts circadian rhythms and redistributes activity during a 16-h sleep opportunity, with no evidence of changes in the duration of endogenous melatonin secretion or pituitary/gonadal hormones. PMID:12970302

Rajaratnam, Shantha M W; Dijk, Derk-Jan; Middleton, Benita; Stone, Barbara M; Arendt, Josephine

2003-09-01

341

The circadian rhythm in Bryophyllum leaves: Phase control by radiant energy  

Microsoft Academic Search

A 4-h exposure to white light from fluorescent lamps can shift the phase of the rhythm of CO2 output in leaves of Bryophyllum fedtschenkoi Hamet & Perr. otherwise kept in continuous darkness. The position in the cycle at which irradiation occurs determines the magnitude and direction of the phase shift. Red and white light induce similar advances or delays in

Philip J. C. Harris; Malcolm B. Wilkins

1978-01-01

342

Melatonin, sleep, and circadian rhythms: rationale for development of specific melatonin agonists  

E-print Network

, which is secreted by the pineal gland. Accumulating evidence suggests that melatonin may regulate rhythm; Sleep; Suprachiasmatic nucleus; Pineal gland; Insomnia 1. Introduction Melatonin, first identified in 1958 [1], is secreted by the pineal gland during the night in a wide range of species

Gillette, Martha U.

343

Quantitative trait loci (QTL) for circadian rhythms of locomotor activity in mice  

Microsoft Academic Search

The loomotor activity of male mice (Mus musculus) was monitored by infrared photoelectric beams under three lighting regimens: LD (12 h of light and 12 h of dark), DD (constant\\u000a dark), and LL (constant broad-spectrum light, 10 lux). Circadian period of locomotor activioty (?) was compared among 3 inbred\\u000a strains of mice, C57BL\\/6J (B6), BALB\\/c (C), and DBA\\/2J (D2), and

John R. Hofstetter; Aimee R. Mayeda; Bernard Possidente; John I. Nurnberger

1995-01-01

344

Integration of human sleep-wake regulation and circadian rhythmicity  

NASA Technical Reports Server (NTRS)

The human sleep-wake cycle is generated by a circadian process, originating from the suprachiasmatic nuclei, in interaction with a separate oscillatory process: the sleep homeostat. The sleep-wake cycle is normally timed to occur at a specific phase relative to the external cycle of light-dark exposure. It is also timed at a specific phase relative to internal circadian rhythms, such as the pineal melatonin rhythm, the circadian sleep-wake propensity rhythm, and the rhythm of responsiveness of the circadian pacemaker to light. Variations in these internal and external phase relationships, such as those that occur in blindness, aging, morning and evening, and advanced and delayed sleep-phase syndrome, lead to sleep disruptions and complaints. Changes in ocular circadian photoreception, interindividual variation in the near-24-h intrinsic period of the circadian pacemaker, and sleep homeostasis can contribute to variations in external and internal phase. Recent findings on the physiological and molecular-genetic correlates of circadian sleep disorders suggest that the timing of the sleep-wake cycle and circadian rhythms is closely integrated but is, in part, regulated differentially.

Dijk, Derk-Jan; Lockley, Steven W.

2002-01-01

345

CLOCK-controlled polyphonic regulation of circadian rhythms through canonical and noncanonical E-boxes.  

PubMed

In mammalian circadian clockwork, the CLOCK-BMAL1 complex binds to DNA enhancers of target genes and drives circadian oscillation of transcription. Here we identified 7,978 CLOCK-binding sites in mouse liver by chromatin immunoprecipitation-sequencing (ChIP-Seq), and a newly developed bioinformatics method, motif centrality analysis of ChIP-Seq (MOCCS), revealed a genome-wide distribution of previously unappreciated noncanonical E-boxes targeted by CLOCK. In vitro promoter assays showed that CACGNG, CACGTT, and CATG(T/C)G are functional CLOCK-binding motifs. Furthermore, we extensively revealed rhythmically expressed genes by poly(A)-tailed RNA-Seq and identified 1,629 CLOCK target genes within 11,926 genes expressed in the liver. Our analysis also revealed rhythmically expressed genes that have no apparent CLOCK-binding site, indicating the importance of indirect transcriptional and posttranscriptional regulations. Indirect transcriptional regulation is represented by rhythmic expression of CLOCK-regulated transcription factors, such as Krüppel-like factors (KLFs). Indirect posttranscriptional regulation involves rhythmic microRNAs that were identified by small-RNA-Seq. Collectively, CLOCK-dependent direct transactivation through multiple E-boxes and indirect regulations polyphonically orchestrate dynamic circadian outputs. PMID:24591654

Yoshitane, Hikari; Ozaki, Haruka; Terajima, Hideki; Du, Ngoc-Hien; Suzuki, Yutaka; Fujimori, Taihei; Kosaka, Naoki; Shimba, Shigeki; Sugano, Sumio; Takagi, Toshihisa; Iwasaki, Wataru; Fukada, Yoshitaka

2014-05-01

346

The effect of bright light therapy on sleep and circadian rhythms in renal transplant recipients: a pilot randomized, multicentre wait-list controlled trial.  

PubMed

This study assessed the effect and feasibility of morning bright light therapy (BLT) on sleep, circadian rhythms, subjective feelings, depressive symptomatology and cognition in renal transplant recipients (RTx) diagnosed with sleep-wake disturbances (SWD). This pilot randomized multicentre wait-list controlled trial included 30 home-dwelling RTx randomly assigned 1:1 to either 3 weeks of BLT or a wait-list control group. Morning BLT (10 000 lux) was individually scheduled for 30 min daily for 3 weeks. Wrist actimetry (measuring sleep and circadian rhythms), validated instruments (subjective feelings and cognition) and melatonin assay (circadian timing) were used. Data were analysed via a random-intercept regression model. Of 30 RTx recipients (aged 58 ± 15, transplanted 15 ± 6 years ago), 26 completed the study. While BLT had no significant effect on circadian and sleep measures, sleep timing improved significantly. The intervention group showed a significant get-up time phase advance from baseline to intervention (+24 min) [(standardized estimates (SE): -0.23 (-0.42; -0.03)] and a small (+14 min) but significant bedtime phase advance from intervention to follow-up (SE: -0.25 (-0.41; -0.09). Improvement in subjective feelings and depressive symptomatology was observed but was not statistically significant. Bright light therapy showed preliminary indications of a beneficial effect in RTx with sleep-wake disturbances. (ClinicalTrials.gov number: NCT01256983). PMID:25182079

Burkhalter, Hanna; Wirz-Justice, Anna; Denhaerynck, Kris; Fehr, Thomas; Steiger, Jürg; Venzin, Reto Martin; Cajochen, Christian; Weaver, Terri Elisabeth; De Geest, Sabina

2015-01-01

347

The importance of circadian rhythms on drug response in hypertension and coronary heart disease--from mice and man.  

PubMed

The cardiovascular system is highly organised in time; blood pressure (BP), heart rate (HR), peripheral resistance, pressure and the release/activity of vasodilating hormones all display pronounced circadian variations. Pathophysiological events within the cardiovascular system are also not random, as shown for instance by sudden cardiac death (SCD), stroke, ventricular arrhythmias (VA), arterial embolism, and symptoms of coronary heart disease (CHD) such as myocardial infarction (MI) and ischemia, angina attacks (AA) in stable angina (stA) or variant angina (varA) or silent ischemia. In hypertensive patients various anti-hypertensive drugs were investigated in crossover studies (morning vs. evening dosing); however consistent data were only obtained for angiotensin-converting enzyme (ACE) inhibitors and calcium channel blockers. Whereas in dippers ACE inhibitors had a super-dipping effect when dosed at night, no consistent difference in BP lowering effect on the 24-hr BP profile was found with calcium channel blockers after morning and evening dosing. In non-dippers the calcium channel blockers isradipine and amlodipine consistently transformed non-dippers into dippers, after evening dosing. Diuretics are also able to normalize a non-dipping behaviour. Moreover, a circadian phase-dependency in pharmacokinetics has been demonstrated for various cardiovascular active drugs such as beta-blockers, calcium channel blockers, oral nitrates and ACE inhibitors, modified by the pharmaceutical formulation. There is evidence that in hypertensive dippers anti-hypertensive drugs should be given in the early morning, whereas in non-dippers it may be necessary to add an evening dose or even to use a single evening dose in order to not only reduce high BP but also to normalize a disturbed non-dipping 24 hr BP profile. In CHD, calcium channel blockers-mainly short acting and non-retarded preparations-seem to be less effective than beta-adrenoceptor antagonists in reducing ischemic events during the night and early morning. However, the role of formulation and/or subclasses of the calcium channel blockers remains to be elucidated. In order to get more insight into the circadian regulation of the cardiovascular system animal models of primary and secondary hypertension have been studied in various strains of normotensive and hypertensive rats and mice. At least in rodents there is ample evidence that the 24-hr rhythms in BP and HR are under the control of biological clock(s) as they persist under constant darkness (i.e. in free-run conditions) with a period deviating from 24 hr; these rhythms are abolished by lesioning of the "master clock" located in the suprachiasmatic nuclei (SCN). In conclusion, chronobiological and chronopharmacological studies are important experimental and clinical approaches to get a better insight into the physiological and pathophysiological regulation of the cardiovascular system including their rhythmic organisation. Circadian time-dependent clinical studies also have implications for drug therapy in hypertension and CHD. PMID:16480770

Lemmer, Björn

2006-09-01

348

Circadian adaptations to meal timing: neuroendocrine mechanisms  

PubMed Central

Circadian rhythms of behavior and physiology are generated by central and peripheral circadian oscillators entrained by periodic environmental or physiological stimuli. A master circadian pacemaker in the hypothalamic suprachiasmatic nucleus (SCN) is directly entrained by daily light-dark (LD) cycles, and coordinates the timing of other oscillators by direct and indirect neural, hormonal and behavioral outputs. The daily rhythm of food intake provides stimuli that entrain most peripheral and central oscillators, some of which can drive a daily rhythm of food anticipatory activity if food is restricted to one daily mealtime. The location of food-entrainable oscillators (FEOs) that drive food anticipatory rhythms, and the food-related stimuli that entrain these oscillators, remain to be clarified. Here, we critically examine the role of peripheral metabolic hormones as potential internal entrainment stimuli or outputs for FEOs controlling food anticipatory rhythms in rats and mice. Hormones for which data are available include corticosterone, ghrelin, leptin, insulin, glucagon, and glucagon-like peptide 1. All of these hormones exhibit daily rhythms of synthesis and secretion that are synchronized by meal timing. There is some evidence that ghrelin and leptin modulate the expression of food anticipatory rhythms, but none of the hormones examined so far are necessary for entrainment. Ghrelin and leptin likely modulate food-entrained rhythms by actions in hypothalamic circuits utilizing melanocortin and orexin signaling, although again food-entrained behavioral rhythms can persist in lesion and gene knockout models in which these systems are disabled. Actions of these hormones on circadian oscillators in central reward circuits remain to be evaluated. Food-entrained activity rhythms are likely mediated by a distributed system of circadian oscillators sensitive to multiple feeding related inputs. Metabolic hormones appear to play a modulatory role within this system. PMID:24133410

Patton, Danica F.; Mistlberger, Ralph E.

2013-01-01

349

Chronic phase advance alters circadian physiological rhythms and peripheral molecular clocks  

PubMed Central

Shifting the onset of light, acutely or chronically, can profoundly affect responses to infection, tumor progression, development of metabolic disease, and mortality in mammals. To date, the majority of phase-shifting studies have focused on acute exposure to a shift in the timing of the light cycle, whereas the consequences of chronic phase shifts alone on molecular rhythms in peripheral tissues such as skeletal muscle have not been studied. In this study, we tested the effect of chronic phase advance on the molecular clock mechanism in two phenotypically different skeletal muscles. The phase advance protocol (CPA) involved 6-h phase advances (earlier light onset) every 4 days for 8 wk. Analysis of the molecular clock, via bioluminescence recording, in the soleus and flexor digitorum brevis (FDB) muscles and lung demonstrated that CPA advanced the phase of the rhythm when studied immediately after CPA. However, if the mice were placed into free-running conditions (DD) for 2 wk after CPA, the molecular clock was not phase shifted in the two muscles but was still shifted in the lung. Wheel running behavior remained rhythmic in CPA mice; however, the endogenous period length of the free-running rhythm was significantly shorter than that of control mice. Core body temperature, cage activity, and heart rate remained rhythmic throughout the experiment, although the onset of the rhythms was significantly delayed with CPA. These results provide clues that lifestyles associated with chronic environmental desynchrony, such as shift work, can have disruptive effects on the molecular clock mechanism in peripheral tissues, including both types of skeletal muscle. Whether this can contribute, long term, to increased incidence of insulin resistance/metabolic disease requires further study. PMID:23703115

Wolff, Gretchen; Duncan, Marilyn J.

2013-01-01

350

Chronic phase advance alters circadian physiological rhythms and peripheral molecular clocks.  

PubMed

Shifting the onset of light, acutely or chronically, can profoundly affect responses to infection, tumor progression, development of metabolic disease, and mortality in mammals. To date, the majority of phase-shifting studies have focused on acute exposure to a shift in the timing of the light cycle, whereas the consequences of chronic phase shifts alone on molecular rhythms in peripheral tissues such as skeletal muscle have not been studied. In this study, we tested the effect of chronic phase advance on the molecular clock mechanism in two phenotypically different skeletal muscles. The phase advance protocol (CPA) involved 6-h phase advances (earlier light onset) every 4 days for 8 wk. Analysis of the molecular clock, via bioluminescence recording, in the soleus and flexor digitorum brevis (FDB) muscles and lung demonstrated that CPA advanced the phase of the rhythm when studied immediately after CPA. However, if the mice were placed into free-running conditions (DD) for 2 wk after CPA, the molecular clock was not phase shifted in the two muscles but was still shifted in the lung. Wheel running behavior remained rhythmic in CPA mice; however, the endogenous period length of the free-running rhythm was significantly shorter than that of control mice. Core body temperature, cage activity, and heart rate remained rhythmic throughout the experiment, although the onset of the rhythms was significantly delayed with CPA. These results provide clues that lifestyles associated with chronic environmental desynchrony, such as shift work, can have disruptive effects on the molecular clock mechanism in peripheral tissues, including both types of skeletal muscle. Whether this can contribute, long term, to increased incidence of insulin resistance/metabolic disease requires further study. PMID:23703115

Wolff, Gretchen; Duncan, Marilyn J; Esser, Karyn A

2013-08-01

351

Photic and nonphotic effects on the circadian activity rhythm in the diurnal rodent Arvicanthis ansorgei.  

PubMed

The main purpose of the study was to compare behavioural properties of entrainment to photic (30 min; 200lx) and nonphotic (melatonin: 1 h; 100 microg) stimuli in the diurnal rodent Arvicanthis ansorgei. Male animals (n=38) were used, and running wheel activity was recorded. Following entrainment to 12:12 h LD the animals were transferred to DD (dim red light) to freerun before treatment started. A phase response curve (PRC) to light was determined showing a phase delay region in the early subjective night (CT 8-16) and a phase advance region in the late subjective night (CT 18-4). Activity onset defined CT=0. Entrainment to daily phase advance and phase delay light pulses occurred at circadian phases corresponding to the respective phase shift regions of the PRC. Similarly, also entrainment to daily melatonin pulses occurred in two narrow time windows located near the beginning (CT 0) and the end of the subjective day (CT 10), but where light had a phase advance effect melatonin had a phase delay effect and vice versa. These results are consistent with the neurobiological model of Hastings et al. (Chronobiol Int 1998;15:425-445) on the differential effects of photic and nonphotic resetting cues on the circadian pacemaker. PMID:16157395

Slotten, Helge A; Krekling, Sturla; Pévet, Paul

2005-11-30

352

The Influence of Light Quality, Circadian Rhythm, and Photoperiod on the CBF-Mediated Freezing Tolerance  

PubMed Central

Low temperature adversely affects crop yields by restraining plant growth and productivity. Most temperate plants have the potential to increase their freezing tolerance upon exposure to low but nonfreezing temperatures, a process known as cold acclimation. Various physiological, molecular, and metabolic changes occur during cold acclimation, which suggests that the plant cold stress response is a complex, vital phenomenon that involves more than one pathway. The C-Repeat Binding Factor (CBF) pathway is the most important and well-studied cold regulatory pathway that imparts freezing tolerance to plants. The regulation of freezing tolerance involves the action of phytochromes, which play an important role in light-mediated signalling to activate cold-induced gene expression through the CBF pathway. Under normal temperature conditions, CBF expression is regulated by the circadian clock through the action of a central oscillator and also day length (photoperiod). The phytochrome and phytochrome interacting factor are involved in the repression of the CBF expression under long day (LD) conditions. Apart from the CBF regulon, a novel pathway involving the Z-box element also mediates the cold acclimation response in a light-dependent manner. This review provides insights into the progress of cold acclimation in relation to light quality, circadian regulation, and photoperiodic regulation and also explains the underlying molecular mechanisms of cold acclimation for introducing the engineering of economically important, cold-tolerant plants. PMID:23722661

Maibam, Punyakishore; Nawkar, Ganesh M.; Park, Joung Hun; Sahi, Vaidurya Pratap; Lee, Sang Yeol; Kang, Chang Ho

2013-01-01

353

Circadian endocrine rhythms: the hypothalamic-pituitary-adrenal axis and its actions.  

PubMed

The stress system effectively restores the internal balance--or homeostasis--of living organisms in the face of random external or internal changes, the stressors. This highly complex system helps organisms to provide a series of neuroendocrine responses to stressors--the stress response--through coordinated activation of the hypothalamic-pituitary-adrenal (HPA) axis and the locus coeruleus/norepinephrine autonomic nervous systems. In addition to stressors, life is influenced by daily light/dark changes due to the 24-h rotation of Earth. To adjust to these recurrent day/night cycles, the biological clock system employs the heterodimer of transcription factors circadian locomotor output cycle kaput/brain-muscle-arnt-like protein 1 (CLOCK/BMAL1), along with a set of other transcription factors, to regulate the circadian pattern of gene expression. Interestingly, the stress system, through the HPA axis, communicates with the clock system; therefore, any uncoupling or dysregulation could potentially cause several disorders, such as metabolic, autoimmune, and mood disorders. In this review, we discuss the biological function of the two systems, their interactions, and the clinical implications of their dysregulation or uncoupling. PMID:24890877

Nicolaides, Nicolas C; Charmandari, Evangelia; Chrousos, George P; Kino, Tomoshige

2014-05-01

354

Plant-Pathogen Interaction, Circadian Rhythm, and Hormone-Related Gene Expression Provide Indicators of Phytoplasma Infection in Paulownia fortunei.  

PubMed

Phytoplasmas are mycoplasma-like pathogens of witches' broom disease, and are responsible for serious yield losses of Paulownia trees worldwide. The molecular mechanisms of disease development in Paulownia are of considerable interest, but still poorly understood. Here, we have applied transcriptome sequencing technology and a de novo assembly approach to analyze gene expression profiles in Paulownia fortunei infected by phytoplasmas. Our previous researches suggested that methyl methane sulfonated (MMS) could reverse the effects of the infection. In this study, leaf samples from healthy, infected, and both infected and methyl methane sulfonate treated plants were analyzed. The results showed that the gene expression profile of P. fortunei underwent dramatic changes after Paulownia witches' broom (PaWB) phytoplasma infection. Genes that encoded key enzymes in plant-pathogen interaction processes were significantly up-regulated in the PaWB-infected Paulownia. Genes involved in circadian rhythm and hormone-related genes were also altered in Paulownia after PaWB infection. However, after the PaWB-infected plants were treated with MMS, the expression profiles of these genes returned to the levels in the healthy controls. The data will help identify potential PaWB disease-resistance genes that could be targeted to inhibit the growth and reproduction of the pathogen and to increase plant resistance. PMID:25514414

Fan, Guoqiang; Dong, Yanpeng; Deng, Minjie; Zhao, Zhenli; Niu, Suyan; Xu, Enkai

2014-01-01

355

Plant-Pathogen Interaction, Circadian Rhythm, and Hormone-Related Gene Expression Provide Indicators of Phytoplasma Infection in Paulownia fortunei  

PubMed Central

Phytoplasmas are mycoplasma-like pathogens of witches’ broom disease, and are responsible for serious yield losses of Paulownia trees worldwide. The molecular mechanisms of disease development in Paulownia are of considerable interest, but still poorly understood. Here, we have applied transcriptome sequencing technology and a de novo assembly approach to analyze gene expression profiles in Paulownia fortunei infected by phytoplasmas. Our previous researches suggested that methyl methane sulfonated (MMS) could reverse the effects of the infection. In this study, leaf samples from healthy, infected, and both infected and methyl methane sulfonate treated plants were analyzed. The results showed that the gene expression profile of P. fortunei underwent dramatic changes after Paulownia witches’ broom (PaWB) phytoplasma infection. Genes that encoded key enzymes in plant-pathogen interaction processes were significantly up-regulated in the PaWB-infected Paulownia. Genes involved in circadian rhythm and hormone-related genes were also altered in Paulownia after PaWB infection. However, after the PaWB-infected plants were treated with MMS, the expression profiles of these genes returned to the levels in the healthy controls. The data will help identify potential PaWB disease-resistance genes that could be targeted to inhibit the growth and reproduction of the pathogen and to increase plant resistance. PMID:25514414

Fan, Guoqiang; Dong, Yanpeng; Deng, Minjie; Zhao, Zhenli; Niu, Suyan; Xu, Enkai

2014-01-01

356

Chronic agomelatine treatment corrects the abnormalities in the circadian rhythm of motor activity and sleep/wake cycle induced by prenatal restraint stress in adult rats.  

PubMed

Agomelatine is a novel antidepressant acting as an MT1/MT2 melatonin receptor agonist/5-HT2C serotonin receptor antagonist. Because of its peculiar pharmacological profile, this drug caters the potential to correct the abnormalities of circadian rhythms associated with mood disorders, including abnormalities of the sleep/wake cycle. Here, we examined the effect of chronic agomelatine treatment on sleep architecture and circadian rhythms of motor activity using the rat model of prenatal restraint stress (PRS) as a putative 'aetiological' model of depression. PRS was delivered to the mothers during the last 10 d of pregnancy. The adult progeny ('PRS rats') showed a reduced duration of slow wave sleep, an increased duration of rapid eye movement (REM) sleep, an increased number of REM sleep events and an increase in motor activity before the beginning of the dark phase of the light/dark cycle. In addition, adult PRS rats showed an increased expression of the transcript of the primary response gene, c-Fos, in the hippocampus just prior to the beginning of the dark phase. All these changes were reversed by a chronic oral treatment with agomelatine (2000 ppm in the diet). The effect of agomelatine on sleep was largely attenuated by treatment with the MT1/MT2 melatonin receptor antagonist, S22153, which caused PRS-like sleep disturbances on its own. These data provide the first evidence that agomelatine corrects sleep architecture and restores circadian homeostasis in a preclinical model of depression and supports the value of agomelatine as a novel antidepressant that resynchronizes circadian rhythms under pathological conditions. PMID:22310059

Mairesse, Jerome; Silletti, Viviana; Laloux, Charlotte; Zuena, Anna Rita; Giovine, Angela; Consolazione, Michol; van Camp, Gilles; Malagodi, Marithe; Gaetani, Silvana; Cianci, Silvia; Catalani, Assia; Mennuni, Gioacchino; Mazzetta, Alessandro; van Reeth, Olivier; Gabriel, Cecilia; Mocaër, Elisabeth; Nicoletti, Ferdinando; Morley-Fletcher, Sara; Maccari, Stefania

2013-03-01

357

[Circadian rhythm disturbance after radiotherapy for brain tumor in infantile period--clinical effect of L-thyroxine and vitamin B12].  

PubMed

We reported here 19-year-old man suffering from circadian sleep-wake (S-W) rhythm disturbance after total tumor resection and whole brain irradiation. This 19-year-old man was diagnosed as having astrocytoma in the right temporal lobe by CT scan and angiography at the age of 6 months. After total tumor resection and whole brain irradiation (60Co 60 Gy), he showed profound psychomotor retardation, endocrinologic dysfunction including hypothyroidism and growth hormone deficiency, and sleep-wake rhythm disturbance. At the age of 19, brain MRI revealed asymmetrical low intensity in the hypothalamic region. On endocrinological examination panhypopituitarism due to primary hypothalamic lesion was evident. His S-W rhythm was disturbed showing a dispersed type sleep, i.e., sleep periods were dispersedly distributed throughout the 24 hours. So he showed a lethargic tendency in the daytime. All-day polysomnography revealed abnormal sleep structure such as the absence of sleep spindle and hump, peripheral apnea, snoring and low oxygen saturation. After L-thyroxine supplementation his daily activity improved gradually. The decrease in short time sleep and tendency of a free-running rhythm were observed and oxygen saturation improved remarkably. Peripheral apnea and snoring disappeared. The wakening effect of L-thyroxine administration may be due to improvement of hypothyroidism symptom such as myxoedematous pharynx. In addition, it seems related to the alteration of the central S-W rhythm regulation, because free-running rhythm appeared after L-thyroxine administration. Vitamin B12 (VB12), which has been reported to be effective for sleep-wake rhythm disorders, was not effective for our patient's free-running rhythm.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8217401

Kubota, M; Shinozaki, M; Sasaki, H

1993-08-01

358

Circadian rhythm disruption by a novel running wheel: roles of exercise and arousal in blockade of the luteinizing hormone surge.  

PubMed

Exposure of proestrous Syrian hamsters to a new room, cage, and novel running wheel blocks the luteinizing hormone (LH) surge until the next day in ~75% of hamsters [1]. The studies described here tested the hypotheses that 1) exercise and/or 2) orexinergic neurotransmission mediate novel wheel blockade of the LH surge and circadian phase advances. Female hamsters were exposed to a 14L:10D photoperiod and activity rhythms were monitored with infra-red detectors. In Expt. 1, to test the effect of exercise, hamsters received jugular cannulae and on the next day, proestrus (Day 1), shortly before zeitgeber time 5 (ZT 5, 7h before lights-off) the hamsters were transported to the laboratory. After obtaining a blood sample at ZT 5, the hamsters were transferred to a new cage with a novel wheel that was either freely rotating (unlocked), or locked until ZT 9, and exposed to constant darkness (DD). Blood samples were collected hourly for 2days from ZT 5-11 under red light for determination of plasma LH levels by radioimmunoassay. Running rhythms were monitored continuously for the next 10-14days. The locked wheels were as effective as unlocked wheels in blocking LH surges (no Day 1 LH surge in 6/9 versus 8/8 hamsters, P>0.05) and phase advances in the activity rhythms did not differ between the groups (P=0.28), suggesting that intense exercise is not essential for novel wheel blockade and phase advance of the proestrous LH surge. Expt. 2 tested whether orexin neurotransmission is essential for these effects. Hamsters were treated the same as those in Expt. 1 except that they were injected (i.p.) at ZT 4.5 and 5 with either the orexin 1 receptor antagonist SB334867 (15mg/kg per injection) or vehicle (25% DMSO in 2-hydroxypropyl-beta-cyclodextrin (HCD)). SB-334867 inhibited novel wheel blockade of the LH surge (surges blocked in 2/6 SB334867-injected animals versus 16/18 vehicle-injected animals, P<0.02) and also inhibited wheel running and circadian phase shifts, indicating that activation of orexin 1 receptors is necessary for these effects. Expt. 3 tested the hypothesis that novel wheel exposure activates orexin neurons. Proestrous hamsters were transferred at ZT 5 to a nearby room within the animal facility and were exposed to a new cage with a locked or unlocked novel wheel or left in their home cages. At ZT 8, the hamsters were anesthetized, blood was withdrawn, they were perfused with fixative and brains were removed for immunohistochemical localization of Fos, GnRH, and orexin. Exposure to a wheel, whether locked or unlocked, suppressed circulating LH concentrations at ZT 8, decreased the proportion of Fos-activated GnRH neurons, and increased Fos-immunoreactive orexin cells. Unlocked wheels had greater effects than locked wheels on all three endpoints. Thus in a familiar environment, exercise potentiated the effect of the novel wheel on Fos expression because a locked wheel was not a sufficient stimulus to block the LH surge. In conclusion, these studies indicate that novel wheel exposure activates orexin neurons and that blockade of orexin 1 receptors prevents novel wheel blockade of the LH surge. These findings are consistent with a role for both exercise and arousal in mediating novel wheel blockade of the LH surge. PMID:24727338

Duncan, Marilyn J; Franklin, Kathleen M; Peng, Xiaoli; Yun, Christopher; Legan, Sandra J

2014-05-28

359

Development of Insect Habitat System for Studying Long Duration Circadian Rhythm Changes on Mir Space Station  

NASA Technical Reports Server (NTRS)

A habitat for housing up to 32 black body beetles (Trigonoscelis gigas) has been developed at Ames Research Center for conducting studies to evaluate the effects of long duration spaceflight upon insect circadian timing systems. This habitat, identified as the Beetle Kit Assembly, provides an automatically controlled lighting system and activity and temperature recording devices, as well as individual beetle enclosures. Each of the 32 enclosures allows for ad lib movement of the beetle, as well as providing a simple food source and allowing ventilation of the beetle volume via an externally operated hand pump. The Beetle Kit Assemblies will be launched on STS-84 (Shuttle-Mir Mission-06) in May, 1997 and will be transferred to the Priroda module of the Russian Mir space station. he beetles will remain on Mir for approximately 125 days, and will be returned to earth on STS-86 in September, 1997.

Savage, P. D.; Hayward, E. F.; Dalton, Bonnie P. (Technical Monitor)

1997-01-01

360

Spotlight on fish: Light pollution affects circadian rhythms of European perch but does not cause stress.  

PubMed

Flora and fauna evolved under natural day and night cycles. However, natural light is now enhanced by artificial light at night, particularly in urban areas. This alteration of natural light environments during the night is hypothesised to alter biological rhythms in fish, by effecting night-time production of the hormone melatonin. Artificial light at night is also expected to increase the stress level of fish, resulting in higher cortisol production. In laboratory experiments, European perch (Perca fluviatilis) were exposed to four different light intensities during the night, 0lx (control), 1lx (potential light level in urban waters), 10lx (typical street lighting at night) and 100lx. Melatonin and cortisol concentrations were measured from water samples every 3h during a 24hour period. This study revealed that the nocturnal increase in melatonin production was inhibited even at the lowest light level of 1lx. However, cortisol levels did not differ between control and treatment illumination levels. We conclude that artificial light at night at very low intensities may disturb biological rhythms in fish since nocturnal light levels around 1lx are already found in urban waters. However, enhanced stress induction could not be demonstrated. PMID:25577738

Brüning, Anika; Hölker, Franz; Franke, Steffen; Preuer, Torsten; Kloas, Werner

2015-04-01

361

Retinoid-related orphan receptors (RORs): critical roles in development, immunity, circadian rhythm, and cellular metabolism  

PubMed Central

The last few years have witnessed a rapid increase in our knowledge of the retinoid-related orphan receptors ROR?, -?, and -? (NR1F1-3), their mechanism of action, physiological functions, and their potential role in several pathologies. The characterization of ROR-deficient mice and gene expression profiling in particular have provided great insights into the critical functions of RORs in the regulation of a variety of physiological processes. These studies revealed that ROR? plays a critical role in the development of the cerebellum, that both ROR? and ROR? are required for the maturation of photoreceptors in the retina, and that ROR? is essential for the development of several secondary lymphoid tissues, including lymph nodes. RORs have been further implicated in the regulation of various metabolic pathways, energy homeostasis, and thymopoiesis. Recent studies identified a critical role for ROR? in lineage specification of uncommitted CD4+ T helper cells into Th17 cells. In addition, RORs regulate the expression of several components of the circadian clock and may play a role in integrating the circadian clock and the rhythmic pattern of expression of downstream (metabolic) genes. Study of ROR target genes has provided insights into the mechanisms by which RORs control these processes. Moreover, several reports have presented evidence for a potential role of RORs in several pathologies, including osteoporosis, several autoimmune diseases, asthma, cancer, and obesity, and raised the possibility that RORs may serve as potential targets for chemotherapeutic intervention. This prospect was strengthened by recent evidence showing that RORs can function as ligand-dependent transcription factors. PMID:19381306

Jetten, Anton M.

2009-01-01

362

The timing of the human circadian clock is accurately represented by the core body temperature rhythm following phase shifts to a three-cycle light stimulus near the critical zone  

NASA Technical Reports Server (NTRS)

A double-stimulus experiment was conducted to evaluate the phase of the underlying circadian clock following light-induced phase shifts of the human circadian system. Circadian phase was assayed by constant routine from the rhythm in core body temperature before and after a three-cycle bright-light stimulus applied near the estimated minimum of the core body temperature rhythm. An identical, consecutive three-cycle light stimulus was then applied, and phase was reassessed. Phase shifts to these consecutive stimuli were no different from those obtained in a previous study following light stimuli applied under steady-state conditions over a range of circadian phases similar to those at which the consecutive stimuli were applied. These data suggest that circadian phase shifts of the core body temperature rhythm in response to a three-cycle stimulus occur within 24 h following the end of the 3-day light stimulus and that this poststimulus temperature rhythm accurately reflects the timing of the underlying circadian clock.

Jewett, M. E.; Duffy, J. F.; Czeisler, C. A.

2000-01-01

363

Molecular Mechanisms of Circadian Regulation During Spaceflight  

NASA Technical Reports Server (NTRS)

The physiology of both vertebrates and invertebrates follows internal rhythms coordinated in phase with the 24-hour daily light cycle. This circadian clock is governed by a central pacemaker, the suprachiasmatic nucleus (SCN) in the brain. However, peripheral circadian clocks or oscillators have been identified in most tissues. How the central and peripheral oscillators are synchronized is still being elucidated. Light is the main environmental cue that entrains the circadian clock. Under the absence of a light stimulus, the clock continues its oscillation in a free-running condition. In general, three functional compartments of the circadian clock are defined. The vertebrate retina contains endogenous clocks that control many aspects of retinal physiology, including retinal sensitivity to light, neurohormone synthesis (melatonin and dopamine), rod disk shedding, signalling pathways and gene expression. Neurons with putative local circadian rhythm generation are found among all the major neuron populations in the mammalian retina. In the mouse, clock genes and function are more localized to the inner retinal and ganglion cell layers. The photoreceptor, however, secrete melatonin which may still serve a an important circadian signal. The reception and transmission of the non-visual photic stimulus resides in a small subpopulation (1-3%) or retinal ganglion cells (RGC) that express the pigment melanopsin (Opn4) and are called intrisically photoreceptive RGC (ipRGC). Melanopsin peak absorption is at 420 nm and all the axons of the ipRGC reach the SCN. A common countermeasure for circadian re-entrainment utilizes blue-green light to entrain the circadian clock and mitigate the risk of fatigue and health and performance decrement due to circadian rhythm disruption. However, an effective countermeasure targeting the photoreceptor system requires that the basic circadian molecular machinery remains intact during spaceflight. We hypothesize that spaceflight may affect ipRGC and melanopsin expression, which may be a contributing cause of circadian disruption during spaceflight.

Zanello, S. B.; Boyle, R.

2012-01-01

364

Role of cardiomyocyte circadian clock in myocardial metabolic adaptation  

Technology Transfer Automated Retrieval System (TEKTRAN)

Marked circadian rhythmicities in cardiovascular physiology and pathophysiology exist. The cardiomyocyte circadian clock has recently been linked to circadian rhythms in myocardial gene expression, metabolism, and contractile function. For instance, the cardiomyocyte circadian clock is essential f...

365

Circadian rhythm in adenosine A1 receptor of mouse cerebral cortex  

SciTech Connect

In order to investigate diurnal variation in adenosine A1 receptors binding parameters, Bmax and Kd values of specifically bound N6-cyclohexyl-({sup 3}H)adenosine were determined in the cerebral cortex of mice that had been housed under controlled light-dark cycles for 4 weeks. Significant differences were found for Bmax values measured at 3-hr intervals across a 24-h period, with low Bmax values during the light period and high Bmax values during the dark period. The amplitude between 03.00 and 18.00 hr was 33%. No substantial rhythm was found in the Kd values. It is suggested that the changes in the density of A1 receptors could reflect a physiologically-relevant mechanism by which adenosine exerts its modulatory role in the central nervous system.

Florio, C.; Rosati, A.M.; Traversa, U.; Vertua, R. (Univ. of Trieste (Italy))

1991-01-01

366

Mechanisms of action of light on circadian rhythms in the monkey.  

PubMed

Light is considered by many investigators to be the primary Zeitgeber for most physiologic rhythms. In order to study the effects on biorhythms of changing photoperiods and to provide information on the nature of the wave forms and the mechanisms of entrainment, unrestrained male monkeys (Cebus albifrons, Macaca nemestrina) were maintained in a sound-proofed environmental chamber. The Cebus was initially maintained on a 12L:12D schedule; it was subjected to a 180 degrees phase shift for 14 days, then returned to the original photoperiod. In two experiments (24 days; 27 days each) the same monkey was again maintained on a 12L:12D schedule which was gradually altered to a constant light environment. Deep body temperature (DBT) data were obtained with miniature radiotransmitters. Locomotor activity (LMA) was measured by strain gauges. Under the 12L:12D regimens the Macaca DBT cycles were uniform as to phase and wave form for over 60 weeks. These wave forms were analyzed by the use of periodogram and correlogram analyses and by fitting to the Volterra Integro-Differential Equation. Phase angle relationships between Zeitgeber and physiologic parameters were characterized. After the photoperiod phase shift the DBT cycle rephased in about 9 days. During the rephasing process the wave form changed. The shapes of the wave forms of DBT and activity were maintained with increasing light until an 18L:6D photoperiod was reached. The rhythms were entrained to the onset of darkness rather than lights on. Major and minor periods of LMA were detected. Hysteresis diagrams showed that DBT led the onset of major LA by 6 hr and the end of major activity by 2 hr. PMID:11826886

Winget, C M; Rosenblatt, L S; DeRoshia, C W; Hetherington, N W

1970-01-01

367

Mechanisms of action of light on circadian rhythms in the monkey  

NASA Technical Reports Server (NTRS)

Light is considered by many investigators to be the primary Zeitgeber for most physiologic rhythms. In order to study the effects on biorhythms of changing photoperiods and to provide information on the nature of the wave forms and the mechanisms of entrainment, unrestrained male monkeys (Cebus albifrons, Macaca nemestrina) were maintained in a sound-proofed environmental chamber. The Cebus was initially maintained on a 12L:12D schedule; it was subjected to a 180 degrees phase shift for 14 days, then returned to the original photoperiod. In two experiments (24 days; 27 days each) the same monkey was again maintained on a 12L:12D schedule which was gradually altered to a constant light environment. Deep body temperature (DBT) data were obtained with miniature radiotransmitters. Locomotor activity (LMA) was measured by strain gauges. Under the 12L:12D regimens the Macaca DBT cycles were uniform as to phase and wave form for over 60 weeks. These wave forms were analyzed by the use of periodogram and correlogram analyses and by fitting to the Volterra Integro-Differential Equation. Phase angle relationships between Zeitgeber and physiologic parameters were characterized. After the photoperiod phase shift the DBT cycle rephased in about 9 days. During the rephasing process the wave form changed. The shapes of the wave forms of DBT and activity were maintained with increasing light until an 18L:6D photoperiod was reached. The rhythms were entrained to the onset of darkness rather than lights on. Major and minor periods of LMA were detected. Hysteresis diagrams showed that DBT led the onset of major LA by 6 hr and the end of major activity by 2 hr.

Winget, C. M.; Rosenblatt, L. S.; DeRoshia, C. W.; Hetherington, N. W.

1970-01-01

368

Evidence of circadian rhythm, oxygen regulation capacity, metabolic repeatability and positive correlations between forced and spontaneous maximal metabolic rates in lake sturgeon Acipenser fulvescens.  

PubMed

Animal metabolic rate is variable and may be affected by endogenous and exogenous factors, but such relationships remain poorly understood in many primitive fishes, including members of the family Acipenseridae (sturgeons). Using juvenile lake sturgeon (Acipenser fulvescens), the objective of this study was to test four hypotheses: 1) A. fulvescens exhibits a circadian rhythm influencing metabolic rate and behaviour; 2) A. fulvescens has the capacity to regulate metabolic rate when exposed to environmental hypoxia; 3) measurements of forced maximum metabolic rate (MMR(F)) are repeatable in individual fish; and 4) MMR(F) correlates positively with spontaneous maximum metabolic rate (MMR(S)). Metabolic rates were measured using intermittent flow respirometry, and a standard chase protocol was employed to elicit MMR(F). Trials lasting 24 h were used to measure standard metabolic rate (SMR) and MMR(S). Repeatability and correlations between MMR(F) and MMR(S) were analyzed using residual body mass corrected values. Results revealed that A. fulvescens exhibit a circadian rhythm in metabolic rate, with metabolism peaking at dawn. SMR was unaffected by hypoxia (30% air saturation (O(2sat))), demonstrating oxygen regulation. In contrast, MMR(F) was affected by hypoxia and decreased across the range from 100% O(2sat) to 70% O(2sat). MMR(F) was repeatable in individual fish, and MMR(F) correlated positively with MMR(S), but the relationships between MMR(F) and MMR(S) were only revealed in fish exposed to hypoxia or 24 h constant light (i.e. environmental stressor). Our study provides evidence that the physiology of A. fulvescens is influenced by a circadian rhythm and suggests that A. fulvescens is an oxygen regulator, like most teleost fish. Finally, metabolic repeatability and positive correlations between MMR(F) and MMR(S) support the conjecture that MMR(F) represents a measure of organism performance that could be a target of natural selection. PMID:24718688

Svendsen, Jon C; Genz, Janet; Anderson, W Gary; Stol, Jennifer A; Watkinson, Douglas A; Enders, Eva C

2014-01-01

369

Evidence of Circadian Rhythm, Oxygen Regulation Capacity, Metabolic Repeatability and Positive Correlations between Forced and Spontaneous Maximal Metabolic Rates in Lake Sturgeon Acipenser fulvescens  

PubMed Central

Animal metabolic rate is variable and may be affected by endogenous and exogenous factors, but such relationships remain poorly understood in many primitive fishes, including members of the family Acipenseridae (sturgeons). Using juvenile lake sturgeon (Acipenser fulvescens), the objective of this study was to test four hypotheses: 1) A. fulvescens exhibits a circadian rhythm influencing metabolic rate and behaviour; 2) A. fulvescens has the capacity to regulate metabolic rate when exposed to environmental hypoxia; 3) measurements of forced maximum metabolic rate (MMRF) are repeatable in individual fish; and 4) MMRF correlates positively with spontaneous maximum metabolic rate (MMRS). Metabolic rates were measured using intermittent flow respirometry, and a standard chase protocol was employed to elicit MMRF. Trials lasting 24 h were used to measure standard metabolic rate (SMR) and MMRS. Repeatability and correlations between MMRF and MMRS were analyzed using residual body mass corrected values. Results revealed that A. fulvescens exhibit a circadian rhythm in metabolic rate, with metabolism peaking at dawn. SMR was unaffected by hypoxia (30% air saturation (O2sat)), demonstrating oxygen regulation. In contrast, MMRF was affected by hypoxia and decreased across the range from 100% O2sat to 70% O2sat. MMRF was repeatable in individual fish, and MMRF correlated positively with MMRS, but the relationships between MMRF and MMRS were only revealed in fish exposed to hypoxia or 24 h constant light (i.e. environmental stressor). Our study provides evidence that the physiology of A. fulvescens is influenced by a circadian rhythm and suggests that A. fulvescens is an oxygen regulator, like most teleost fish. Finally, metabolic repeatability and positive correlations between MMRF and MMRS support the conjecture that MMRF represents a measure of organism performance that could be a target of natural selection. PMID:24718688

Svendsen, Jon C.; Genz, Janet; Anderson, W. Gary; Stol, Jennifer A.; Watkinson, Douglas A.; Enders, Eva C.

2014-01-01

370

Cold-Induced Cysts of the Photosynthetic Dinoflagellate Lingulodinium polyedrum Have an Arrested Circadian Bioluminescence Rhythm and Lower Levels of Protein Phosphorylation1[C][W  

PubMed Central

Dinoflagellates are microscopic, eukaryotic, and primarily marine plankton. Temporary cyst formation is a well-known physiological response of dinoflagellate cells to environmental stresses. However, the molecular underpinnings of cold-induced cyst physiology have never been described. Cultures of the photosynthetic dinoflagellate Lingulodinium polyedrum readily form temporary cysts when placed at low (8°C ± 1°C) temperature and excyst to form normal motile cells following a return to normal temperature (18°C ± 1°C). The normal circadian bioluminescence rhythm and the expected changes in Luciferin Binding Protein abundance were arrested in L. polyedrum cysts. Furthermore, after excystment, the bioluminescence rhythm initiates at a time corresponding to zeitgeber 12, independent of the time when the cells encysted. Phosphoprotein staining after two-dimensional polyacrylamide gel electrophoresis, as well as column-based phosphoprotein enrichment followed by liquid chromatography tandem mass spectrometry, showed cyst proteins are hypophosphorylated when compared with those from motile cells, with the most marked decreases found for predicted Casein Kinase2 target sites. In contrast to the phosphoproteome, the cyst proteome is not markedly different from motile cells, as assessed by two-dimensional polyacrylamide gel electrophoresis. In addition to changes in the phosphoproteome, RNA sequencing revealed that cysts show a significant decrease in the levels of 132 RNAs. Of the 42 RNAs that were identified by sequence analysis, 21 correspond to plastid-encoded gene products and 11 to nuclear-encoded cell wall/plasma membrane components. Our data are consistent with a model in which the highly reduced metabolism in cysts is achieved primarily by alterations in the phosphoproteome. The stalling of the circadian rhythm suggests temporary cysts may provide an interesting model to address the circadian system of dinoflagellates. PMID:24335505

Roy, Sougata; Letourneau, Louis; Morse, David

2014-01-01

371

Cold-induced cysts of the photosynthetic dinoflagellate Lingulodinium polyedrum have an arrested circadian bioluminescence rhythm and lower levels of protein phosphorylation.  

PubMed

Dinoflagellates are microscopic, eukaryotic, and primarily marine plankton. Temporary cyst formation is a well-known physiological response of dinoflagellate cells to environmental stresses. However, the molecular underpinnings of cold-induced cyst physiology have never been described. Cultures of the photosynthetic dinoflagellate Lingulodinium polyedrum readily form temporary cysts when placed at low (8°C±1°C) temperature and excyst to form normal motile cells following a return to normal temperature (18°C±1°C). The normal circadian bioluminescence rhythm and the expected changes in Luciferin Binding Protein abundance were arrested in L. polyedrum cysts. Furthermore, after excystment, the bioluminescence rhythm initiates at a time corresponding to zeitgeber 12, independent of the time when the cells encysted. Phosphoprotein staining after two-dimensional polyacrylamide gel electrophoresis, as well as column-based phosphoprotein enrichment followed by liquid chromatography tandem mass spectrometry, showed cyst proteins are hypophosphorylated when compared with those from motile cells, with the most marked decreases found for predicted Casein Kinase2 target sites. In contrast to the phosphoproteome, the cyst proteome is not markedly different from motile cells, as assessed by two-dimensional polyacrylamide gel electrophoresis. In addition to changes in the phosphoproteome, RNA sequencing revealed that cysts show a significant decrease in the levels of 132 RNAs. Of the 42 RNAs that were identified by sequence analysis, 21 correspond to plastid-encoded gene products and 11 to nuclear-encoded cell wall/plasma membrane components. Our data are consistent with a model in which the highly reduced metabolism in cysts is achieved primarily by alterations in the phosphoproteome. The stalling of the circadian rhythm suggests temporary cysts may provide an interesting model to address the circadian system of dinoflagellates. PMID:24335505

Roy, Sougata; Letourneau, Louis; Morse, David

2014-02-01

372

RNA-sequencing of the brain transcriptome implicates dysregulation of neuroplasticity, circadian rhythms and GTPase binding in bipolar disorder.  

PubMed

RNA-sequencing (RNA-seq) is a powerful technique to investigate the complexity of gene expression in the human brain. We used RNA-seq to survey the brain transcriptome in high-quality postmortem dorsolateral prefrontal cortex from 11 individuals diagnosed with bipolar disorder (BD) and from 11 age- and gender-matched controls. Deep sequencing was performed, with over 350 million reads per specimen. At a false discovery rate of <5%, we detected five differentially expressed (DE) genes and 12 DE transcripts, most of which have not been previously implicated in BD. Among these, Prominin 1/CD133 and ATP-binding cassette-sub-family G-member2 (ABCG2) have important roles in neuroplasticity. We also show for the first time differential expression of long noncoding RNAs (lncRNAs) in BD. DE transcripts include those of serine/arginine-rich splicing factor 5 (SRSF5) and regulatory factor X4 (RFX4), which along with lncRNAs have a role in mammalian circadian rhythms. The DE genes were significantly enriched for several Gene Ontology categories. Of these, genes involved with GTPase binding were also enriched for BD-associated SNPs from previous genome-wide association studies, suggesting that differential expression of these genes is not simply a consequence of BD or its treatment. Many of these findings were replicated by microarray in an independent sample of 60 cases and controls. These results highlight common pathways for inherited and non-inherited influences on disease risk that may constitute good targets for novel therapies. PMID:24393808

Akula, N; Barb, J; Jiang, X; Wendland, J R; Choi, K H; Sen, S K; Hou, L; Chen, D T W; Laje, G; Johnson, K; Lipska, B K; Kleinman, J E; Corrada-Bravo, H; Detera-Wadleigh, S; Munson, P J; McMahon, F J

2014-11-01

373

Circadian rhythms, Wnt/beta-catenin pathway and PPAR alpha/gamma profiles in diseases with primary or secondary cardiac dysfunction  

PubMed Central

Circadian clock mechanisms are far-from-equilibrium dissipative structures. Peroxisome proliferator-activated receptors (PPAR alpha, beta/delta, and gamma) play a key role in metabolic regulatory processes, particularly in heart muscle. Links between circadian rhythms (CRs) and PPARs have been established. Mammalian CRs involve at least two critical transcription factors, CLOCK and BMAL1 (Gekakis et al., 1998; Hogenesch et al., 1998). PPAR gamma plays a major role in both glucose and lipid metabolisms and presents circadian properties which coordinate the interplay between metabolism and CRs. PPAR gamma is a major component of the vascular clock. Vascular PPAR gamma is a peripheral regulator of cardiovascular rhythms controlling circadian variations in blood pressure and heart rate through BMAL1. We focused our review on diseases with abnormalities of CRs and with primary or secondary cardiac dysfunction. Moreover, these diseases presented changes in the Wnt/beta-catenin pathway and PPARs, according to two opposed profiles. Profile 1 was defined as follows: inactivation of the Wnt/beta-catenin pathway with increased expression of PPAR gamma. Profile 2 was defined as follows: activation of the Wnt/beta-catenin pathway with decreased expression of PPAR gamma. A typical profile 1 disease is arrhythmogenic right ventricular cardiomyopathy, a genetic cardiac disease which presents mutations of the desmosomal proteins and is mainly characterized by fatty acid accumulation in adult cardiomyocytes mainly in the right ventricle. The link between PPAR gamma dysfunction and desmosomal genetic mutations occurs via inactivation of the Wnt/beta-catenin pathway presenting oscillatory properties. A typical profile 2 disease is type 2 diabetes, with activation of the Wnt/beta-catenin pathway and decreased expression of PPAR gamma. CRs abnormalities are present in numerous pathologies such as cardiovascular diseases, sympathetic/parasympathetic dysfunction, hypertension, diabetes, neurodegenerative diseases, cancer which are often closely inter-related. PMID:25414671

Lecarpentier, Yves; Claes, Victor; Duthoit, Guillaume; Hébert, Jean-Louis

2014-01-01

374

Molecular Mechanisms Underlying the Arabidopsis Circadian Clock  

PubMed Central

A wide range of biological processes exhibit circadian rhythm, enabling plants to adapt to the environmental day–night cycle. This rhythm is generated by the so-called ‘circadian clock’. Although a number of genetic approaches have identified >25 clock-associated genes involved in the Arabidopsis clock mechanism, the molecular functions of a large part of these genes are not known. Recent comprehensive studies have revealed the molecular functions of several key clock-associated proteins. This progress has provided mechanistic insights into how key clock-associated proteins are integrated, and may help in understanding the essence of the clock's molecular mechanisms. PMID:21873329

Nakamichi, Norihito

2011-01-01

375

Association between mammalian lifespan and circadian free-running period: the circadian resonance hypothesis revisited  

PubMed Central

Biological rhythms that oscillate with periods close to 24 h (circadian cycles) are pervasive features of mammalian physiology, facilitating entrainment to the 24 h cycle generated by the rotation of the Earth. In the absence of environmental time cues, circadian rhythms default to their endogenous period called tau, or the free-running period. This sustained circadian rhythmicity in constant conditions has been reported across the animal kingdom, a ubiquity that could imply that innate rhythmicity confers an adaptive advantage. In this study, we found that the deviation of tau from 24 h was inversely related to the lifespan in laboratory mouse strains, and in other rodent and primate species. These findings support the hypothesis that misalignment of endogenous rhythms and 24 h environmental cycles may be associated with a physiological cost that has an effect on longevity. PMID:20392719

Wyse, C. A.; Coogan, A. N.; Selman, C.; Hazlerigg, D. G.; Speakman, J. R.

2010-01-01

376

Coordination of circadian timing in mammals  

Microsoft Academic Search

Time in the biological sense is measured by cycles that range from milliseconds to years. Circadian rhythms, which measure time on a scale of 24 h, are generated by one of the most ubiquitous and well-studied timing systems. At the core of this timing mechanism is an intricate molecular mechanism that ticks away in many different tissues throughout the body.

Steven M. Reppert; David R. Weaver

2002-01-01

377

Respiration Physiology 122 (2000) 131147 Respiratory rhythm generation in neonatal and adult  

E-print Network

Respiration Physiology 122 (2000) 131­147 Respiratory rhythm generation in neonatal and adult Koshiya a , Christopher Del Negro a , Christopher G. Wilson a , Sheree M. Johnson a a Cellular and Systems synthesis of cellular and network mechanisms that can theoretically account for rhythm generation

Del Negro, Christopher A.

378

The Roles of the Dimeric and Tetrameric Structures of the Clock Protein KaiB in the Generation of Circadian Oscillations in Cyanobacteria*  

PubMed Central

The molecular machinery of the cyanobacterial circadian clock consists of three proteins, KaiA, KaiB, and KaiC. The three Kai proteins interact with each other and generate circadian oscillations in vitro in the presence of ATP (an in vitro KaiABC clock system). KaiB consists of four subunits organized as a dimer of dimers, and its overall shape is that of an elongated hexagonal plate with a positively charged cleft flanked by two negatively charged ridges. We found that a mutant KaiB with a C-terminal deletion (KaiB1–94), which lacks the negatively charged ridges, was a dimer. Despite its dimeric structure, KaiB1–94 interacted with KaiC and generated normal circadian oscillations in the in vitro KaiABC clock system. KaiB1–94 also generated circadian oscillations in cyanobacterial cells, but they were weak, indicating that the C-terminal region and tetrameric structure of KaiB are necessary for the generation of normal gene expression rhythms in vivo. KaiB1–94 showed the highest affinity for KaiC among the KaiC-binding proteins we examined and inhibited KaiC from forming a complex with SasA, which is involved in the main output pathway from the KaiABC clock oscillator in transcription regulation. This defect explains the mechanism underlying the lack of normal gene expression rhythms in cells expressing KaiB1–94. PMID:22722936

Murakami, Reiko; Mutoh, Risa; Iwase, Ryo; Furukawa, Yukio; Imada, Katsumi; Onai, Kiyoshi; Morishita, Megumi; Yasui, So; Ishii, Kentaro; Valencia Swain, Jonathan Orville; Uzumaki, Tatsuya; Namba, Keiichi; Ishiura, Masahiro

2012-01-01

379

Circadian Rhythm in the Expression of the mRNA Coding for the Apoprotein of the Light-Harvesting Complex of Photosystem II 1  

PubMed Central

The mRNA coding for light-harvesting complex of PSII (LHC-II) apoprotein is present in etiolated bean (Phaseolus vulgaris L.) leaves; its level is low in 5-day-old leaves, increases about 3 to 4 times in 9- to 13-day-old leaves, and decreases thereafter. A red light pulse induces an increase in LHC-II mRNA level, which is reversed by far red light, in all ages of the etiolated tissue tested. The phytochrome-controlled initial increase of LHC-II mRNA level is higher in 9- and 13-day-old than in 5- and 17-day-old bean leaves. The amount of LHC-II mRNA, accumulated in the dark after a red light pulse, oscillates rhythmically with a period of about 24 hours. This rhythm is also observed in continuous white light and in the dark following exposure to continuous white light, and persists for at least 70 hours. A second red light pulse, applied 36 hours after initiation of the rhythm, induces a phase-shift, which is prevented by far red light immediately following the second red light pulse. A persistent, but gradually reduced, far red reversibility of the red light-induced increase in LHC-II mRNA level is observed. In contrast, far red reversibility of the red light-induced clock setting is only observed when far red follows immediately the red light. It is concluded that (a) the light-induced LHC-II mRNA accumulation follows an endogenous, circadian rhythm, for the appearance of which a red light pulse is sufficient, (b) the circadian oscillator is under phytochrome control, and (c) a stable Pfr form, which exists for several hours, is responsible for sustaining LHC-II gene transcription. Images Figure 1 Figure 2 Figure 8 PMID:16666825

Tavladoraki, Paraskevi; Kloppstech, Klaus; Argyroudi-Akoyunoglou, Joan

1989-01-01

380

A Novel Pathophysiologic Phenomenon in Cachexic Patients with Chronic Obstructive Pulmonary Disease The Relationship between the Circadian Rhythm of Circulating Leptin and the Very Low-Frequency Component of Heart Rate Variability  

Microsoft Academic Search

Cachexic patients with chronic obstructive pulmonary disease (COPD) show abnormalities of the autonomic nervous system (ANS), neuroendocrine function, and energy expenditure. Leptin has been implicated in the regulation of ANS, neuroendocine function, and thermogenesis in humans. We assessed the physiologic signifi- cance of the circadian rhythm of circulating leptin using power spectrum analysis of heart rate variability (HRV) in nine

NORIAKI TAKABATAKE; HIDENORI NAKAMURA; OSAMU MINAMIHABA; MINORU INAGE; SUMITO INOUE; SHIGERU KAGAYA; MICHIYASU YAMAKI; HITONOBU TOMOIKE

381

Circadian rhythm in rest and activity: a biological correlate of quality of life and a predictor of survival in patients with metastatic colorectal cancer  

PubMed Central

The rest/activity circadian rhythm (CircAct) reflects the function of the circadian timing system (CTS). In a prior single-institution study, the extent of CircAct perturbation independently predicted for survival and tumor response in 192 patients receiving chemotherapy for metastatic colorectal cancer (MCRC). Moreover, the main CircAct parameters correlated with several quality of life (HRQoL) scales. In this prospective study we attempted to extend these results to an independent cohort of chemotherapy-naïve MCRC patients participating in an international randomized phase III trial (EORTC 05963). Patients were randomized to receive chronomodulated or conventional infusion of 5-fluorouracil, leucovorin and oxaliplatin as first line treatment for MCRC. Patients from nine institutions completed the EORTC QLQ-C30, and wore a wrist-accelerometer (actigraph) for 3 days before chemotherapy delivery. Two validated parameters (I|0.25|, p<0.01). Icircadian timing system constitutes a novel therapeutic target. Interventions that normalize circadian timing system dysfunction may impact quality of life and survival in cancer patients PMID:19470769

Innominato, Pasquale F.; Focan, Christian; Gorlia, Thierry; Moreau, Thierry; Garufi, Carlo; Waterhouse, Jim; Giacchetti, Sylvie; Coudert, Bruno; Iacobelli, Stefano; Genet, Dominique; Tampellini, Marco; Chollet, Philippe; Lentz, Marie-Ange; Mormont, Marie-Christine; Lévi, Francis; Bjarnason, Georg A.

2009-01-01

382

Cardiac Atrial Circadian Rhythms in PERIOD2::LUCIFERASE and per1:luc Mice: Amplitude and Phase Responses to Glucocorticoid Signaling and Medium Treatment  

PubMed Central

Circadian rhythms in cardiac function are apparent in e.g., blood pressure, heart rate, and acute adverse cardiac events. A circadian clock in heart tissue has been identified, but entrainment pathways of this clock are still unclear. We cultured tissues of mice carrying bioluminescence reporters of the core clock genes, period 1 or 2 (per1luc or PER2LUC) and compared in vitro responses of atrium to treatment with medium and a synthetic glucocorticoid (dexamethasone [DEX]) to that of the suprachiasmatic nucleus (SCN) and liver. We observed that PER2LUC, but not per1luc is rhythmic in atrial tissue, while both per1luc and PER2LUC exhibit rhythmicity in other cultured tissues. In contrast to the SCN and liver, both per1luc and PER2LUC bioluminescence amplitudes were increased in response to DEX treatment, and the PER2LUC amplitude response was dependent on the time of treatment. Large phase-shift responses to both medium and DEX treatments were observed in the atrium, and phase responses to medium treatment were not attributed to serum content but the treatment procedure itself. The phase-response curves of atrium to both DEX and medium treatments were found to be different to the liver. Moreover, the time of day of the culturing procedure itself influenced the phase of the circadian clock in each of the cultured tissues, but the magnitude of this response was uniquely large in atrial tissue. The current data describe novel entrainment signals for the atrial circadian clock and specifically highlight entrainment by mechanical treatment, an intriguing observation considering the mechanical nature of cardiac tissue. PMID:23110090

Xi, Yang; Li, Lei; Duffield, Giles E.

2012-01-01

383

Circadian activity rhythms and voluntary ethanol intake in male and female ethanol-preferring rats: Effects of long-term ethanol access.  

PubMed

Chronic alcohol (ethanol) intake alters fundamental properties of the circadian clock. While previous studies have reported significant alterations in free-running circadian period during chronic ethanol access, these effects are typically subtle and appear to require high levels of intake. In the present study we examined the effects of long-term voluntary ethanol intake on ethanol consumption and free-running circadian period in male and female, selectively bred ethanol-preferring P and HAD2 rats. In light of previous reports that intermittent access can result in escalated ethanol intake, an initial 2-week water-only baseline was followed by either continuous or intermittent ethanol access (i.e., alternating 15-day epochs of ethanol access and ethanol deprivation) in separate groups of rats. Thus, animals were exposed to either 135 days of continuous ethanol access or to five 15-day access periods alternating with four 15-day periods of ethanol deprivation. Animals were maintained individually in running-wheel cages under continuous darkness throughout the experiment to allow monitoring of free-running activity and drinking rhythms, and 10% (v/v) ethanol and plain water were available continuously via separate drinking tubes during ethanol access. While there were no initial sex differences in ethanol drinking, ethanol preference increased progressively in male P and HAD2 rats under both continuous and intermittent-access conditions, and eventually exceeded that seen in females. Free-running period shortened during the initial ethanol-access epoch in all groups, but the persistence of this effect showed complex dependence on sex, breeding line, and ethanol-access schedule. Finally, while females of both breeding lines displayed higher levels of locomotor activity than males, there was little evidence for modulation of activity level by ethanol access. These results are consistent with previous findings that chronic ethanol intake alters free-running circadian period, and show further that the development of chronobiological tolerance to ethanol may vary by sex and genotype. PMID:25281289

Rosenwasser, Alan M; McCulley, Walter D; Fecteau, Matthew

2014-11-01

384

The melatonin rhythm-generating enzyme: molecular regulation of serotonin N-acetyltransferase in the pineal gland.  

PubMed

A remarkably constant feature of vertebrate physiology is a daily rhythm of melatonin in the circulation, which serves as the hormonal signal of the daily light/dark cycle: melatonin levels are always elevated at night. The biochemical basis of this hormonal rhythm is one of the enzymes involved in melatonin synthesis in the pineal gland-the melatonin rhythm-generating enzyme-serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase, AA-NAT, E.C. 2.3.1.87). In all vertebrates, enzyme activity is high at night. This reflects the influences of internal circadian clocks and of light. The dynamics of this enzyme are remarkable. The magnitude of the nocturnal increase in enzyme activity ranges from 7- to 150-fold on a species-to-species basis among vertebrates. In all cases the nocturnal levels of AA-NAT activity decrease very rapidly following exposure to light. A major advance in the study of the molecular basis of these changes was the cloning of cDNA encoding the enzyme. This has resulted in rapid progress in our understanding of the biology and structure of AA-NAT and how it is regulated. Several constant features of this enzyme have become apparent, including structural features, tissue distribution, and a close association of enzyme activity and protein. However, some remarkable differences among species in the molecular mechanisms involved in regulating the enzyme have been discovered. In sheep, AA-NAT mRNA levels show relatively little change over a 24-hour period and changes in AA-NAT activity are primarily regulated at the protein level. In the rat, AA-NAT is also regulated at a protein level; however, in addition, AA-NAT mRNA levels exhibit a 150-fold rhythm, which reflects cyclic AMP-dependent regulation of expression of the AA-NAT gene. In the chicken, cyclic AMP acts primarily at the protein level and a rhythm in AA-NAT mRNA is driven by a noncyclic AMP-dependent mechanism linked to the clock within the pineal gland. Finally, in the trout, AA-NAT mRNA levels show little change and activity is regulated by light acting directly on the pineal gland. The variety of mechanisms that have evolved among vertebrates to achieve the same goal-a rhythm in melatonin-underlines the important role melatonin plays as the hormonal signal of environmental lighting in vertebrates. PMID:9238858

Klein, D C; Coon, S L; Roseboom, P H; Weller, J L; Bernard, M; Gastel, J A; Zatz, M; Iuvone, P M; Rodriguez, I R; Bégay, V; Falcón, J; Cahill, G M; Cassone, V M; Baler, R

1997-01-01

385

An Artificial Vector Model for Generating Abnormal Electrocardiographic Rhythms  

PubMed Central

We present generalizations of our previously published artificial models for generating multi-channel ECG to provide simulations of abnormal cardiac rhythms. Using a three-dimensional vectorcardiogram (VCG) formulation, we generate the normal cardiac dipole for a patient using a sum of Gaussian kernels, fitted to real VCG recordings. Abnormal beats are specified either as perturbations to the normal dipole or as new dipole trajectories. Switching between normal and abnormal beat types is achieved using a first-order Markov chain. Probability transitions can be learned from real data or modeled by coupling to heart rate and sympathovagal balance. Natural morphology changes from beat-to-beat are incorporated by varying the angular frequency of the dipole as a function of the inter-beat (RR) interval. The RR interval time series is generated using our previously described model whereby time- and frequency-domain heart rate (HR) and heart rate variability characteristics can be specified. QT-HR hysteresis is simulated by coupling the Gaussian kernels associated with the T-wave in the model with a nonlinear factor related to the local HR (determined from the last n RR intervals). Morphology changes due to respiration are simulated by introducing a rotation matrix couple to the respiratory frequency. We demonstrate an example of the use of this model by simulating HR-dependent T-Wave Alternans (TWA) with and without phase-switching due to ectopy. Application of our model also reveals previously unreported effects of common TWA estimation methods. PMID:20308774

Clifford, Gari D.; Nemati, Shamim; Sameni, Reza

2010-01-01

386

Suprachiasmatic nuclei and Circadian rhythms. The role of suprachiasmatic nuclei on rhythmic activity of neurons in the lateral hypothalamic area, ventromedian nuclei and pineal gland  

NASA Technical Reports Server (NTRS)

Unit activity of lateral hypothalamic area (LHA) and Ventromedian nuclei (VMN) was recorded in urethane anesthetized male rats. A 5 to 10 sec. a 3-5 min and a circadian rhythmicity were observed. In about 15% of all neurons, spontaneous activity of LHA and VMN showed reciprocal relationships. Subthreshold stimuli applied at a slow rate in the septum and the suprachiasmatic nuclei (SCN) suppressed the rhythms without changing firing rates. On the other hand, stimulation of the optic nerve at a rate of 5 to 10/sec increased firing rates in 1/3 of neurons of SCN. Iontophoretically applied acetylcholine increased 80% of tested neurons of SCN, whereas norepinephrine, dopamine and 5 HT inhibited 64, 60 and 75% of SCN neurons respectively. These inhibitions were much stronger in neurons, the activity of which was increased by optic nerve stimulation. Stimulation of the SCN inhibited the tonic activity in cervical sympathetic nerves.

Nishino, H.

1977-01-01

387

Shifting the Circadian Rhythm of Feeding in Mice Induces Gastrointestinal, Metabolic and Immune Alterations Which Are Influenced by Ghrelin and the Core Clock Gene Bmal1  

PubMed Central

Background In our 24-hour society, an increasing number of people are required to be awake and active at night. As a result, the circadian rhythm of feeding is seriously compromised. To mimic this, we subjected mice to restricted feeding (RF), a paradigm in which food availability is limited to short and unusual times of day. RF induces a food-anticipatory increase in the levels of the hunger hormone ghrelin. We aimed to investigate whether ghrelin triggers the changes in body weight and gastric emptying that occur during RF. Moreover, the effect of genetic deletion of the core clock gene Bmal1 on these physiological adaptations was studied. Methods Wild-type, ghrelin receptor knockout and Bmal1 knockout mice were fed ad libitum or put on RF with a normal or high-fat diet (HFD). Plasma ghrelin levels were measured by radioimmunoassay. Gastric contractility was studied in vitro in muscle strips and in vivo (13C breath test). Cytokine mRNA expression was quantified and infiltration of immune cells was assessed histologically. Results The food-anticipatory increase in plasma ghrelin levels induced by RF with normal chow was abolished in HFD-fed mice. During RF, body weight restoration was facilitated by ghrelin and Bmal1. RF altered cytokine mRNA expression levels and triggered contractility changes resulting in an accelerated gastric emptying, independent from ghrelin signaling. During RF with a HFD, Bmal1 enhanced neutrophil recruitment to the stomach, increased gastric IL-1? expression and promoted gastric contractility changes. Conclusions This is the first study demonstrating that ghrelin and Bmal1 regulate the extent of body weight restoration during RF, whereas Bmal1 controls the type of inflammatory infiltrate and contractility changes in the stomach. Disrupting the circadian rhythm of feeding induces a variety of diet-dependent metabolic, immune and gastrointestinal alterations, which may explain the higher prevalence of obesity and immune-related gastrointestinal disorders among shift workers. PMID:25329803

Laermans, Jorien; Broers, Charlotte; Beckers, Kelly; Vancleef, Laurien; Steensels, Sandra; Thijs, Theo; Tack, Jan; Depoortere, Inge

2014-01-01