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Nouha Souayed, Malek Chennoufi, Nadia Ben Frej, Amel Chaabane, Mossadok Ben-Attia, Karim Aouam, Alain Reinberg, Naceur A Boughattas
INTRODUCTION: This study is designed to investigate whether the pharmacokinetics of the antituberculous agent isoniazid (INH) varied according to the circadian dosing-time. METHODS: A total of 168 male mice aged 10 weeks and synchronized for 3 weeks to 12h light and 12h dark were used. A single INH (100mg/kg) dose was administered by intraperitonal (i.p.) route at either of the four different circadian stages (1, 7, 13 and 19h after light onset, HALO). At each circadian stage, blood samples were withdrawn at 0, 0...
October 22, 2016: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
Melissa A Wren-Dail, Robert T Dauchy, Tara G Ooms, Kate C Baker, David E Blask, Steven M Hill, Lynell M Dupepe, Rudolf P Bohm
Environmental enrichment (EE) gives laboratory animals opportunities to engage in species-specific behaviors. However, the effects of EE devices on normal physiology and scientific outcomes must be evaluated. We hypothesized that the spectral transmittance (color) of light to which rats are exposed when inside colored enrichment devices (CED) affects the circadian rhythms of various plasma markers. Pair-housed male Crl:SD rats were maintained in ventilated racks under a 12:12-h light:dark environment (265.0 lx; lights on, 0600); room lighting intensity and schedule remained constant throughout the study...
2016: Comparative Medicine
Robert T Dauchy, Melissa A Wren-Dail, Aaron E Hoffman, John P Hanifin, Benjamin Warfield, George C Brainard, Steven M Hill, Victoria P Belancio, Erin M Dauchy, David E Blask
Regular cycles of exposure to light and dark control pineal melatonin production and temporally coordinate circadian rhythms of metabolism and physiology in mammals. Previously we demonstrated that the peak circadian amplitude of nocturnal blood melatonin levels of rats were more than 6-fold higher after exposure to cool white fluorescent (CWF) light through blue-tinted (compared with clear) rodent cages. Here, we evaluated the effects of light-phase exposure of rats to white light-emitting diodes (LED), which emit light rich in the blue-appearing portion of the visible spectrum (465-485 nm), compared with standard broadspectrum CWF light, on melatonin levels during the subsequent dark phase and on plasma measures of metabolism and physiology...
2016: Comparative Medicine
Bertel T Hansen, Kim M Sønderskov, Ida Hageman, Peter T Dinesen, Søren D Østergaard
BACKGROUND: Daylight savings time transitions affect approximately 1.6 billion people worldwide. Prior studies have documented associations between daylight savings time transitions and adverse health outcomes, but it remains unknown whether they also cause an increase in the incidence rate of depressive episodes. This seems likely because daylight savings time transitions affect circadian rhythms, which are implicated in the etiology of depressive disorder. Therefore, we investigated the effects of daylight savings time transitions on the incidence rate of unipolar depressive episodes...
October 20, 2016: Epidemiology
Sherie Ma, Craig M Smith, Anna Blasiak, Andrew L Gundlach
Relaxin-3 is a member of a superfamily of structurally-related peptides that includes relaxin and insulin-like peptide hormones. Soon after the discovery of the relaxin-3 gene, relaxin-3 was identified as an abundant neuropeptide in brain with a distinctive topographical distribution within a small number of GABA neuron populations that is well conserved across species. Relaxin-3 is thought to exert its biological actions through a single class-A GPCR - relaxin-family peptide receptor 3 (RXFP3). Class-A comprises GPCRs for relaxin-3 and insulin-like peptide-5 and other peptides such as orexin and the monoamine transmitters...
October 23, 2016: British Journal of Pharmacology
Yaling Wu, Dingbin Tang, Na Liu, Wei Xiong, Huanwei Huang, Yang Li, Zhixiong Ma, Haijiao Zhao, Peihao Chen, Xiangbing Qi, Eric Erquan Zhang
Circadian regulation is critically important in maintaining metabolic and physiological homeostasis. However, little is known about the possible influence of the clock on physiological abnormalities occurring under pathological conditions. Here, we report the discovery that hypoxia, a condition that causes catastrophic bodily damage, is gated by the circadian clock in vivo. Hypoxia signals conversely regulate the clock by slowing the circadian cycle and dampening the amplitude of oscillations in a dose-dependent manner...
October 14, 2016: Cell Metabolism
Clara Bien Peek, Daniel C Levine, Jonathan Cedernaes, Akihiko Taguchi, Yumiko Kobayashi, Stacy J Tsai, Nicolle A Bonar, Maureen R McNulty, Kathryn Moynihan Ramsey, Joseph Bass
Circadian clocks are encoded by a transcription-translation feedback loop that aligns energetic processes with the solar cycle. We show that genetic disruption of the clock activator BMAL1 in skeletal myotubes and fibroblasts increased levels of the hypoxia-inducible factor 1α (HIF1α) under hypoxic conditions. Bmal1(-/-) myotubes displayed reduced anaerobic glycolysis, mitochondrial respiration with glycolytic fuel, and transcription of HIF1α targets Phd3, Vegfa, Mct4, Pk-m, and Ldha, whereas abrogation of the clock repressors CRY1/2 stabilized HIF1α in response to hypoxia...
October 19, 2016: Cell Metabolism
Yaarit Adamovich, Benjamin Ladeuix, Marina Golik, Maarten P Koeners, Gad Asher
The mammalian circadian system consists of a master clock in the brain that synchronizes subsidiary oscillators in peripheral tissues. The master clock maintains phase coherence in peripheral cells through systemic cues such as feeding-fasting and temperature cycles. Here, we examined the role of oxygen as a resetting cue for circadian clocks. We continuously measured oxygen levels in living animals and detected daily rhythms in tissue oxygenation. Oxygen cycles, within the physiological range, were sufficient to synchronize cellular clocks in a HIF1α-dependent manner...
October 19, 2016: Cell Metabolism
Germaine Cornelissen, Kuniaki Otsuka
Aging is generally associated with weakening of the circadian system. The circadian amplitude is reduced and the circadian acrophase becomes more labile, tending to occur earlier with advancing age. As originally noted by Franz Halberg, similar features are observed in the experimental laboratory after bilateral lesioning of the suprachiasmatic nuclei, suggesting the involvement of clock genes in the aging process as they are in various disease conditions. Recent work has been shedding light on underlying pathways involved in the aging process, with the promise of interventions to extend healthy life spans...
October 22, 2016: Gerontology
Cinthia D Coria-Lucero, Rebeca S Golini, Ivana T Ponce, Nicolas Deyurka, Ana C Anzulovich, Silvia M Delgado, Lorena S Navigatore-Fonzo
Aging brain undergoes several changes leading to a decline in cognitive functions. Memory and learning-related genes such as Creb, Bdnf and its receptor TrkB, are expressed in different brain regions including prefrontal cortex. Those genes' proteins regulate a wide range of functions such as synaptic plasticity and long-term potentiation. In this work, our objectives were: 1) to investigate whether Creb1, Bdnf and TrkB genes display endogenous circadian expression rhythms, in the prefrontal cortex of rats maintained under constant darkness conditions; 2) to study the synchronization of those temporal patterns to the local cellular clock and 3) to evaluate the aging consequences on both cognition-related genes and activating clock transcription factor, BMAL1, rhythms...
October 19, 2016: Brain Research
Yanzhu Lin, Zhen-Xia Chen, Brian Oliver, Susan T Harbison
Differences in phenotype among genetically identical individuals exposed to the same environmental condition are often noted in genetic studies. Despite this commonplace observation, little is known about the causes of this variability, which has been termed microenvironmental plasticity. One possibility is that stochastic or technical sources of variance produce these differences. A second possibility is that this variation has a genetic component. We have explored gene expression robustness in the transcriptomes of 730 individual Drosophila melanogaster of 16 fixed genotypes, 9 of which are infected with Wolbachia Three replicates of flies were grown controlling for food, day/night cycles, humidity, temperature, sex, mating status, social exposure, and circadian timing of RNA extraction...
October 21, 2016: G3: Genes—Genomes—Genetics
Sonja Rutten, Chris Vriend, Jan H Smit, Henk W Berendse, Adriaan W Hoogendoorn, Odile A van den Heuvel, Ysbrand D van der Werf
BACKGROUND: A disturbed circadian rhythm seems to be a causal factor in the occurrence of depressive disorders in patients with Parkinson's disease (PD). The circadian rhythm can be restored with light. Therefore, Bright Light Therapy (BLT) might be a new treatment option for depression in PD patients. METHODS/DESIGN: In this double-blind controlled trial, 84 subjects with idiopathic PD are randomized to either BLT or a control light condition. The BLT condition emits white light with an intensity of 10,000 Lux, while the control device emits dim white light of 200 Lux, which is presumed to be too low to influence the circadian rhythm...
October 21, 2016: BMC Psychiatry
Andreas Arendt, El-Sayed Baz, Monika Stengl
The circadian pacemaker of the Madeira cockroach Rhyparobia (Leucophaea) maderae is located in the accessory medulla (AME). Ipsi- and contralateral histaminergic compound eyes are required for photic entrainment. Light pulses delayed locomotor activity rhythms during the early night and advanced during the late night. Thus, different neuronal pathways might relay either light-dependent delays or advances to the clock. Injections of neuroactive substances combined with running-wheel assays suggested that GABA, PDF, myoinhibitory peptides (MIPs), and orcokinins (ORCs) are part of both entrainment pathways, while allatotropin (AT) only delayed locomotor rhythms at the early night...
October 20, 2016: Journal of Comparative Neurology
Víctor Resco de Dios, Arthur Gessler, Juan Pedro Ferrio, Josu G Alday, Michael Bahn, Jorge Del Castillo, Sébastien Devidal, Sonia García-Muñoz, Zachary Kayler, Damien Landais, Paula Martín-Gómez, Alexandru Milcu, Clément Piel, Karin Pirhofer-Walzl, Olivier Ravel, Serajis Salekin, David T Tissue, Mark G Tjoelker, Jordi Voltas, Jacques Roy
BACKGROUND: Molecular clocks drive oscillations in leaf photosynthesis, stomatal conductance, and other cell and leaf-level processes over ~24 h under controlled laboratory conditions. The influence of such circadian regulation over whole-canopy fluxes remains uncertain; diurnal CO2 and H2O vapor flux dynamics in the field are currently interpreted as resulting almost exclusively from direct physiological responses to variations in light, temperature and other environmental factors. We tested whether circadian regulation would affect plant and canopy gas exchange at the Montpellier European Ecotron...
October 20, 2016: GigaScience
Gregory D M Potter, Debra J Skene, Josephine Arendt, Janet E Cade, Peter J Grant, Laura J Hardie
Circadian (∼ 24 hour) timing systems pervade all kingdoms of life, and temporally optimize behaviour and physiology in humans. Relatively recent changes to our environments, such as the introduction of artificial lighting, can disorganize the circadian system, from the level of the molecular clocks that regulate the timing of cellular activities to the level of synchronization between our daily cycles of behaviour and the solar day. Sleep/wake cycles are intertwined with the circadian system, and global trends indicate that these too are increasingly subject to disruption...
October 20, 2016: Endocrine Reviews
Rüdiger Hardeland
Dynamic aspects of melatonin's actions merit increasing future attention. This concerns particularly entirely different effects in senescent, weakened oscillators and in dysregulated oscillators of cancer cells that may be epigenetically blocked. This is especially obvious in the case of sirtuin 1 (SIRT1) which is upregulated by melatonin in aged tissues, but strongly downregulated in several cancer cells. These findings are not at all controversial, but are explained on the basis of divergent changes in weakened and dysregulated oscillators...
October 20, 2016: Journal of Pineal Research
Dirk Jan Stenvers, Rick van Dorp, Ewout Foppen, Jorge Mendoza, Anne-Loes Opperhuizen, Eric Fliers, Peter H Bisschop, Johanna H Meijer, Andries Kalsbeek, Tom Deboer
Exposure to light at night (LAN) is associated with insomnia in humans. Light provides the main input to the master clock in the hypothalamic suprachiasmatic nucleus (SCN) that coordinates the sleep-wake cycle. We aimed to develop a rodent model for the effects of LAN on sleep. Therefore, we exposed male Wistar rats to either a 12 h light (150-200lux):12 h dark (LD) schedule or a 12 h light (150-200 lux):12 h dim white light (5 lux) (LDim) schedule. LDim acutely decreased the amplitude of daily rhythms of REM and NREM sleep, with a further decrease over the following days...
October 20, 2016: Scientific Reports
Joseph F O'Grady, Laura S Hoelters, Martin T Swain, David C Wilcockson
BACKGROUND: Talitrus saltator is an amphipod crustacean that inhabits the supralittoral zone on sandy beaches in the Northeast Atlantic and Mediterranean. T. saltator exhibits endogenous locomotor activity rhythms and time-compensated sun and moon orientation, both of which necessitate at least one chronometric mechanism. Whilst their behaviour is well studied, currently there are no descriptions of the underlying molecular components of a biological clock in this animal, and very few in other crustacean species...
2016: PeerJ
Kevin A McGoff, Xin Guo, Anastasia Deckard, Christina M Kelliher, Adam R Leman, Lauren J Francey, John B Hogenesch, Steven B Haase, John L Harer
We present a novel approach, the Local Edge Machine, for the inference of regulatory interactions directly from time-series gene expression data. We demonstrate its performance, robustness, and scalability on in silico datasets with varying behaviors, sizes, and degrees of complexity. Moreover, we demonstrate its ability to incorporate biological prior information and make informative predictions on a well-characterized in vivo system using data from budding yeast that have been synchronized in the cell cycle...
October 19, 2016: Genome Biology
Aurore Woller, Hélène Duez, Bart Staels, Marc Lefranc
To maintain energy homeostasis despite variable energy supply and consumption along the diurnal cycle, the liver relies on a circadian clock synchronized to food timing. Perturbed feeding and fasting cycles have been associated with clock disruption and metabolic diseases; however, the mechanisms are unclear. To address this question, we have constructed a mathematical model of the mammalian circadian clock, incorporating the metabolic sensors SIRT1 and AMPK. The clock response to various temporal patterns of AMPK activation was simulated numerically, mimicking the effects of a normal diet, fasting, and a high-fat diet...
October 18, 2016: Cell Reports
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