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https://www.readbyqxmd.com/read/27920039/systems-chronobiology-global-analysis-of-gene-regulation-in-a-24-hour-periodic-world
#1
Jérôme Mermet, Jake Yeung, Felix Naef
Mammals have evolved an internal timing system, the circadian clock, which synchronizes physiology and behavior to the daily light and dark cycles of the Earth. The master clock, located in the suprachiasmatic nucleus (SCN) of the brain, takes fluctuating light input from the retina and synchronizes other tissues to the same internal rhythm. The molecular clocks that drive these circadian rhythms are ticking in nearly all cells in the body. Efforts in systems chronobiology are now being directed at understanding, on a comprehensive scale, how the circadian clock controls different layers of gene regulation to provide robust timing cues at the cellular and tissue level...
December 5, 2016: Cold Spring Harbor Perspectives in Biology
https://www.readbyqxmd.com/read/27916729/enkephalin-and-neuropeptide-y-interaction-in-the-intergeniculate-leaflet-network-a-part-of-the-mammalian-biological-clock
#2
K Palus, L Chrobok, M Kepczynski, M H Lewandowski
The intergeniculate leaflet (IGL) is a flat thalamic nucleus implicated in the modulation of circadian rhythmicity. In rat, two main GABAergic subpopulations can be distinguished in the IGL: neurons synthesising neuropeptide Y (NPY), which directly innervates the suprachiasmatic nuclei, and enkephalinergic cells, which connect contralaterally located leaflets. The aim of this study was to evaluate possible effects of inner IGL neurotransmitters on the spontaneous and synaptic activity of IGL neurons. The data presented in this article provide evidence that enkephalin, and not NPY, could act upon the majority of IGL neurons...
December 1, 2016: Neuroscience
https://www.readbyqxmd.com/read/27906111/the-functional-significance-of-the-skeletal-muscle-clock-lessons-from-bmal1-knockout-models
#3
REVIEW
Stefano Schiaffino, Bert Blaauw, Kenneth A Dyar
The circadian oscillations of muscle genes are controlled either directly by the intrinsic muscle clock or by extrinsic factors, such as feeding, hormonal signals, or neural influences, which are in turn regulated by the central pacemaker, the suprachiasmatic nucleus of the hypothalamus. A unique feature of circadian rhythms in skeletal muscle is motor neuron-dependent contractile activity, which can affect the oscillation of a number of muscle genes independently of the muscle clock. The role of the intrinsic muscle clock has been investigated using different Bmal1 knockout (KO) models...
October 13, 2016: Skeletal Muscle
https://www.readbyqxmd.com/read/27894927/the-dynamics-of-gaba-signaling-revelations-from-the-circadian-pacemaker-in-the-suprachiasmatic-nucleus
#4
REVIEW
H Elliott Albers, James C Walton, Karen L Gamble, John K McNeill, Daniel L Hummer
Virtually every neuron within the suprachiasmatic nucleus (SCN) communicates via GABAergic signaling. The extra-cellular levels of GABA within the SCN are determined by a complex interaction of synthesis and transport, as well as synaptic and non-synaptic release. The response to GABA is mediated by GABAA receptors that respond to both phasic and tonic GABA release and that can produce excitatory as well as inhibitory cellular responses. GABA also influences circadian control through the exclusively inhibitory effects of GABAB receptors...
November 25, 2016: Frontiers in Neuroendocrinology
https://www.readbyqxmd.com/read/27869182/the-effects-of-non-self-sustained-oscillators-on-the-en-trainment-ability-of-the-suprachiasmatic-nucleus
#5
Changgui Gu, Ming Tang, Jos H T Rohling, Huijie Yang
In mammals, the circadian rhythms of behavioral and physiological activities are regulated by an endogenous clock located in the suprachiasmatic nucleus (SCN). The SCN is composed of ~20,000 neurons, of which some are capable of self-sustained oscillations, while the others do not oscillate in a self-sustainable manner, but show arrhythmic patterns or damped oscillations. Thus far, the effects of these non-self-sustained oscillatory neurons are not fully explored. Here, we examined how the proportion of the non-self-sustained oscillators affects the free running period under constant darkness and the ability to entrain to the light-dark cycle...
November 21, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27852737/role-of-fructose-and-fructokinase-in-acute-dehydration-induced-vasopressin-gene-expression-and-secretion-in-mice
#6
Zhilin Song, Carlos A Roncal-Jimenez, Miguel A Lanaspa-Garcia, Sarah A Oppelt, Masanari Kuwabara, Thomas Jensen, Tamara Milagres, Ana Andres-Hernando, Takuji Ishimoto, Gabriela E Garcia, Ginger C Johnson, Paul S MacLean, Laura-Gabriela Sanchez-Lozada, Dean R Tolan, Richard J Johnson
BACKGROUND: Fructose stimulates vasopressin in humans and can be generated endogenously by activation of the polyol pathway with hyperosmolarity. We hypothesized that fructose metabolism in the hypothalamus might partly control vasopressin responses after acute dehydration. METHODS: Wildtype and fructokinase-knockout mice were deprived of water for 24 hours. The supraoptic nucleus was evaluated for vasopressin and the aldose reductase-fructokinase pathway. The posterior pituitary vasopressin and serum copeptin levels were examined...
November 16, 2016: Journal of Neurophysiology
https://www.readbyqxmd.com/read/27826225/single-cell-transcriptional-analysis-reveals-novel-neuronal-phenotypes-and-interaction-networks-involved-in-the-central-circadian-clock
#7
James Park, Haisun Zhu, Sean O'Sullivan, Babatunde A Ogunnaike, David R Weaver, James S Schwaber, Rajanikanth Vadigepalli
Single-cell heterogeneity confounds efforts to understand how a population of cells organizes into cellular networks that underlie tissue-level function. This complexity is prominent in the mammalian suprachiasmatic nucleus (SCN). Here, individual neurons exhibit a remarkable amount of asynchronous behavior and transcriptional heterogeneity. However, SCN neurons are able to generate precisely coordinated synaptic and molecular outputs that synchronize the body to a common circadian cycle by organizing into cellular networks...
2016: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/27824104/degeneration-and-energy-shortage-in-the-suprachiasmatic-nucleus-underlies-the-circadian-rhythm-disturbance-in-apoe-mice-implications-for-alzheimer-s-disease
#8
Lan Zhou, Qian Gao, Meng Nie, Jing-Li Gu, Wei Hao, Lin Wang, Ji-Min Cao
Alzheimer's disease (AD) patients suffer sleep disorders and circadian rhythm disturbances (CRDs). The underlying mechanisms are incompletely understood, and treatments are lacking. In this study, we characterized the locomotor activity, clock gene expression, morphological degeneration and energy metabolism of suprachiasmatic nucleus (SCN), together with retinal light sensing, in ApoE(-/-) mice, a model for AD. Compared with the control C57BL/6J mice, ApoE(-/-) mice exhibited disordered circadian locomotor activity under dim light and constant darkness, with impaired re-entrainment to phase change schedules...
November 8, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27802074/gestational-chronodisruption-impairs-circadian-physiology-in-rat-male-offspring-increasing-the-risk-of-chronic-disease
#9
Natalia Mendez, Diego Halabi, Carlos Spichiger, Esteban R Salazar, Karina Vergara, Pamela Alonso-Vasquez, Pamela Carmona, Jose M Sarmiento, Hans G Richter, Maria Seron-Ferre, Claudia Torres-Farfan
Chronic exposure to light at night, as in shift work, alters biological clocks (chronodisruption), negatively impacting pregnancy outcome in humans. Actually the interaction of maternal and fetal circadian systems could be a key factor determining a fitting health in adults. We propose that chronic photoperiod shift (CPS) during pregnancy alter maternal circadian rhythms and impair circadian physiology in the adult offspring, increasing health risks. Pregnant rats were exposed to normal photoperiod (12 h light, 12 h dark) or to CPS until 85% of gestation...
December 2016: Endocrinology
https://www.readbyqxmd.com/read/27790157/influence-of-time-of-day-on-maximal-exercise-capacity-is-related-to-daily-thermal-balance-but-not-to-induced-neuronal-activity-in-rats
#10
Frederico S M Machado, Daniela R C Fóscolo, Maristela O Poletini, Cândido C Coimbra
In the present study, we investigated whether the daily fluctuations of internal body temperature (Tb) and spontaneous locomotor activity (SLA) interact with the thermal and neuronal adjustments induced by high-intensity aerobic exercise until fatigue. The body temperature and SLA of adult Wistar rats (n = 23) were continuously recorded by telemetry for 48 h. Then, the rats were subjected to a protocol of graded exercise until fatigue or rest on the treadmill during light and dark-phases. Tb, tail skin temperature and ambient temperature during each experimental session were recorded...
2016: Frontiers in Physiology
https://www.readbyqxmd.com/read/27781473/resynchronization-of-circadian-oscillators-and-the-east-west-asymmetry-of-jet-lag
#11
Zhixin Lu, Kevin Klein-Cardeña, Steven Lee, Thomas M Antonsen, Michelle Girvan, Edward Ott
Cells in the brain's Suprachiasmatic Nucleus (SCN) are known to regulate circadian rhythms in mammals. We model synchronization of SCN cells using the forced Kuramoto model, which consists of a large population of coupled phase oscillators (modeling individual SCN cells) with heterogeneous intrinsic frequencies and external periodic forcing. Here, the periodic forcing models diurnally varying external inputs such as sunrise, sunset, and alarm clocks. We reduce the dimensionality of the system using the ansatz of Ott and Antonsen and then study the effect of a sudden change of clock phase to simulate cross-time-zone travel...
September 2016: Chaos
https://www.readbyqxmd.com/read/27771730/spatiotemporal-development-of-the-orexinergic-hypocretinergic-system-in-the-central-nervous-system-of-xenopus-laevis
#12
Jesús M López, Lorena Morales, Agustín González
The present immunohistochemical study represents a detailed spatiotemporal analysis of the localization of orexin-immunoreactive (OX-ir) cells and fibers throughout development in the brain of the anuran amphibian Xenopus laevis, a model frequently used in developmental studies. Anurans undergo remarkable physiological changes during the early life stages, and very little is known about the ontogeny and the localization of the centers that control functions such as appetite and feed ingestion in the developing brain...
2016: Brain, Behavior and Evolution
https://www.readbyqxmd.com/read/27762290/dim-light-at-night-disturbs-the-daily-sleep-wake-cycle-in-the-rat
#13
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
https://www.readbyqxmd.com/read/27752300/the-functional-significance-of-the-skeletal-muscle-clock-lessons-from-bmal1-knockout-models
#14
Stefano Schiaffino, Bert Blaauw, Kenneth A Dyar
The circadian oscillations of muscle genes are controlled either directly by the intrinsic muscle clock or by extrinsic factors, such as feeding, hormonal signals, or neural influences, which are in turn regulated by the central pacemaker, the suprachiasmatic nucleus of the hypothalamus. A unique feature of circadian rhythms in skeletal muscle is motor neuron-dependent contractile activity, which can affect the oscillation of a number of muscle genes independently of the muscle clock. The role of the intrinsic muscle clock has been investigated using different Bmal1 knockout (KO) models...
2016: Skeletal Muscle
https://www.readbyqxmd.com/read/27749086/the-functional-and-clinical-significance-of-the-24-h-rhythm-of-circulating-glucocorticoids
#15
Henrik Oster, Etienne Challet, Volker Ott, Emanuela Arvat, E Ronald de Kloet, Derk-Jan Dijk, Stafford Lightman, Alexandros Vgontzas, Eve Van Cauter
Adrenal glucocorticoids are major modulators of multiple functions, including energy metabolism, stress responses, immunity, and cognition. The endogenous secretion of glucocorticoids is normally characterized by a prominent and robust circadian (around 24 hours) oscillation, with a daily peak around the time of the habitual sleep-wake transition and minimal levels in the evening and early part of the night. It has been long recognized that this 24-h rhythm partly reflects the activity of a master circadian pacemaker located in the suprachiasmatic nucleus of the hypothalamus...
October 17, 2016: Endocrine Reviews
https://www.readbyqxmd.com/read/27740710/differential-localization-of-per1-and-per2-in-the-brain-master-circadian-clock
#16
Malini Riddle, Erica Mezias, Duncan Foley, Joseph LeSauter, Rae Silver
The hypothalamic suprachiasmatic nucleus (SCN), locus of the master circadian clock, bears many neuronal types. At the cellular-molecular level, the clock is comprised of feedback loops involving 'clock' genes including Period1 and Period2, and their protein products, PERIOD1 and PERIOD2 (PER1/2). In the canonical model of circadian oscillation, the PER1/2 proteins oscillate together. While their rhythmic expression in the SCN as a whole has been described, the possibility of regional differences remains unknown...
October 14, 2016: European Journal of Neuroscience
https://www.readbyqxmd.com/read/27733449/learned-motivation-drives-circadian-physiology-in-the-absence-of-the-master-circadian-clock
#17
Oliver Rawashdeh, Shannon J Clough, Randall L Hudson, Margarita L Dubocovich
The suprachiasmatic nucleus (SCN)-often referred to as the master circadian clock-is essential in generating physiologic rhythms and orchestrating synchrony among circadian clocks. This study tested the hypothesis that periodic motivation induced by rhythmically pairing 2 reinforcing stimuli [methamphetamine (Meth) and running wheel (RW)] restores autonomous circadian activity in arrhythmic SCN-lesioned (SCNX) C3H/HeN mice. Sham-surgery and SCNX mice were treated with either Meth (1.2 mg/kg, i.p.) or vehicle in association, dissociation, or absence of an RW...
October 12, 2016: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
https://www.readbyqxmd.com/read/27712099/the-pathophysiologic-role-of-disrupted-circadian-and-neuroendocrine-rhythms-in-breast-carcinogenesis
#18
Lonnele J Ball, Oxana Palesh, Lance J Kriegsfeld
Most physiological processes in the brain and body exhibit daily (circadian) rhythms coordinated by an endogenous master clock located in the suprachiasmatic nucleus of the hypothalamus that are essential for normal health and functioning. Exposure to sunlight during the day and darkness at night optimally entrains biological rhythms to promote homeostasis and human health. Unfortunately, a major consequence of the modern lifestyle is increased exposure to sun-free environments during the day and artificial lighting at night...
October 2016: Endocrine Reviews
https://www.readbyqxmd.com/read/27704948/bmal1-is-required-for-normal-reproductive-behaviors-in-male-mice
#19
Erica L Schoeller, Daniel D Clark, Sandeepa Dey, Nathan V Cao, Sheila J Semaan, Ling W Chao, Alexander S Kauffman, Lisa Stowers, Pamela L Mellon
Circadian rhythms synchronize physiological processes with the light-dark cycle and are regulated by a hierarchical system initiated in the suprachiasmatic nucleus, a hypothalamic region that receives direct photic input. The suprachiasmatic nucleus then entrains additional oscillators in the periphery. Circadian rhythms are maintained by a molecular transcriptional feedback loop, of which brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein 1 (BMAL1) is a key member. Disruption of circadian rhythms by deletion of the BMAL1 gene (Bmal1 knockout [KO]) induces a variety of disease states, including infertility in males, due to unidentified mechanisms...
December 2016: Endocrinology
https://www.readbyqxmd.com/read/27702781/differential-phasing-between-circadian-clocks-in-the-brain-and-peripheral-organs-in-humans
#20
Jacob J Hughey, Atul J Butte
The daily timing of mammalian physiology is coordinated by circadian clocks throughout the body. Although measurements of clock gene expression indicate that these clocks in mice are normally in phase with each other, the situation in humans remains unclear. We used publicly available data from five studies, comprising over 1000 samples, to compare the phasing of circadian gene expression in human brain and human blood. Surprisingly, after controlling for age, clock gene expression in brain was phase-delayed by ~8...
October 4, 2016: Journal of Biological Rhythms
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