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suprachiasmatic nucleus

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https://www.readbyqxmd.com/read/28430522/impact-of-naturalistic-lighting-on-hospitalized-stroke-patients-in-a-rehabilitation-unit-design-and-measurement
#1
Anders West, Poul Jennum, Sofie Amalie Simonsen, Birgit Sander, Milena Pavlova, Helle K Iversen
INTRODUCTION AND RATIONALE: Stroke is a major cause of acquired cerebral disability among adults, frequently accompanied by depression, anxiety, cognitive impairment, disrupted sleep and fatigue. New ways of intervention to prevent these complications are therefore needed. The major circadian regulator, the suprachiasmatic nucleus, is mainly controlled by natural daylight, and the blue spectrum is considered the most powerful. During stroke rehabilitation, patients typically are mostly indoors and therefore not exposed to the natural daytime variation in light intensity...
April 21, 2017: Chronobiology International
https://www.readbyqxmd.com/read/28425198/the-cell-adhesion-molecule-epha4-is-involved-in-circadian-clock-functions
#2
Silke Kiessling, Emma K O'Callaghan, Marlène Freyburger, Nicolas Cermakian, Valérie Mongrain
Circadian (~24 h) rhythms of cellular network plasticity in the central circadian clock, the suprachiasmatic nucleus (SCN), have been described. The neuronal network in the SCN regulates photic resetting of the circadian clock as well as stability of the circadian system during both entrained and constant conditions. EphA4, a cell adhesion molecule regulating synaptic plasticity by controlling connections of neurons and astrocytes, is expressed in the SCN. To address whether EphA4 plays a role in circadian photoreception and influences the neuronal network of the SCN, we have analysed circadian wheel-running behavior of EphA4 knockout (EphA4(-/-) ) mice under different light conditions and upon photic resetting, as well as their light-induced protein response in the SCN...
April 20, 2017: Genes, Brain, and Behavior
https://www.readbyqxmd.com/read/28423315/mir-132-212-modulates-seasonal-adaptation-and-dendritic-morphology-of-the-central-circadian-clock
#3
Lucia Mendoza-Viveros, Cheng-Kang Chiang, Jonathan L K Ong, Sara Hegazi, Arthur H Cheng, Pascale Bouchard-Cannon, Michael Fana, Christopher Lowden, Peng Zhang, Béatrice Bothorel, Matthew G Michniewicz, Stephen T Magill, Melissa M Holmes, Richard H Goodman, Valérie Simonneaux, Daniel Figeys, Hai-Ying M Cheng
The central circadian pacemaker, the suprachiasmatic nucleus (SCN), encodes day length information by mechanisms that are not well understood. Here, we report that genetic ablation of miR-132/212 alters entrainment to different day lengths and non-24 hr day-night cycles, as well as photoperiodic regulation of Period2 expression in the SCN. SCN neurons from miR-132/212-deficient mice have significantly reduced dendritic spine density, along with altered methyl CpG-binding protein (MeCP2) rhythms. In Syrian hamsters, a model seasonal rodent, day length regulates spine density on SCN neurons in a melatonin-independent manner, as well as expression of miR-132, miR-212, and their direct target, MeCP2...
April 18, 2017: Cell Reports
https://www.readbyqxmd.com/read/28423013/mapping-the-co-localization-of-the-circadian-proteins-per2-and-bmal1-with-enkephalin-and-substance-p-throughout-the-rodent-forebrain
#4
Ariana Frederick, Jory Goldsmith, Nuria de Zavalia, Shimon Amir
Despite rhythmic expression of clock genes being found throughout the central nervous system, very little is known about their function outside of the suprachiasmatic nucleus. Determining the pattern of clock gene expression across neuronal subpopulations is a key step in understanding their regulation and how they may influence the functions of various brain structures. Using immunofluorescence and confocal microscopy, we quantified the co-expression of the clock proteins BMAL1 and PER2 with two neuropeptides, Substance P (SubP) and Enkephalin (Enk), expressed in distinct neuronal populations throughout the forebrain...
2017: PloS One
https://www.readbyqxmd.com/read/28416676/dissociation-of-per1-and-bmal1-circadian-rhythms-in-the-suprachiasmatic-nucleus-in-parallel-with-behavioral-outputs
#5
Daisuke Ono, Sato Honma, Yoshihiro Nakajima, Shigeru Kuroda, Ryosuke Enoki, Ken-Ichi Honma
The temporal order of physiology and behavior in mammals is primarily regulated by the circadian pacemaker located in the hypothalamic suprachiasmatic nucleus (SCN). Taking advantage of bioluminescence reporters, we monitored the circadian rhythms of the expression of clock genes Per1 and Bmal1 in the SCN of freely moving mice and found that the rate of phase shifts induced by a single light pulse was different in the two rhythms. The Per1-luc rhythm was phase-delayed instantaneously by the light presented at the subjective evening in parallel with the activity onset of behavioral rhythm, whereas the Bmal1-ELuc rhythm was phase-delayed gradually, similar to the activity offset...
April 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28415286/dissociation-between-two-subgroups-of-the-suprachiasmatic-nucleus-affected-by-the-number-of-damped-oscillated-neurons
#6
Changgui Gu, Huijie Yang, Jos Ht Rohling
In mammals, the main clock located in the suprachiasmatic nucleus (SCN) of the brain synchronizes the body rhythms to the environmental light-dark cycle. The SCN is composed of about 2×10^{4} neurons which can be classified into three oscillatory phenotypes: self-sustained oscillators, damped oscillators, and arrhythmic neurons. Exposed to an artificial external light-dark cycle with a period of 22h instead of 24h, two subgroups of the SCN can become desynchronized (dissociated). The ventrolateral (VL) subgroup receives photic input and is entrained to the external cycle and a dorsomedial (DM) subgroup oscillates with its endogenous (i...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28402052/vasopressin-casts-light-on-the-suprachiasmatic-nucleus
#7
Takahiro Tsuji, Andrew J Allchorne, Meng Zhang, Chiharu Tsuji, Vicky A Tobin, Rafael Pineda, Androniki Raftogianni, Javier E Stern, Valery Grinevich, Gareth Leng, Mike Ludwig
In all animals, the transition between night and day engages a host of physiological and behavioural rhythms. These rhythms depend not on the rods and cones of the retina, but on retinal ganglion cells (RGCs) that detect the ambient light level in the environment. These project to the suprachiasmatic nucleus (SCN) of the hypothalamus to entrain circadian rhythms that are generated within the SCN. The neuropeptide vasopressin has an important role in this entrainment. Many SCN neurons express vasopressin, and it has been assumed that the role of vasopressin in the SCN reflects the activity of these cells...
April 12, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28401917/cooperative-roles-of-the-suprachiasmatic-nucleus-central-clock-and-the-adrenal-clock-in-controlling-circadian-glucocorticoid-rhythm
#8
Sooyoung Chung, Eun Jeong Lee, Hyo Kyeong Cha, Jeongah Kim, Doyeon Kim, Gi Hoon Son, Kyungjin Kim
The mammalian circadian timing system consists of the central clock in the hypothalamic suprachiasmatic nucleus (SCN) and subsidiary peripheral clocks in other tissues. Glucocorticoids (GCs) are adrenal steroid hormones with widespread physiological effects that undergo daily oscillations. We previously demonstrated that the adrenal peripheral clock plays a pivotal role in circadian GC rhythm by driving cyclic GC biosynthesis. Here, we show that the daily rhythm in circulating GC levels is controlled by bimodal actions of central and adrenal clockwork...
April 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28390292/functional-connectivity-of-the-circadian-clock-and-neural-substrates-of-sleep-wake-disturbance-in-delirium
#9
Sunghyon Kyeong, Soo-Hee Choi, Jung Eun Shin, Woo Suk Lee, Kyu Hyun Yang, Tae-Sub Chung, Jae-Jin Kim
A possible mechanism of disrupted circadian rhythms in delirium was identified using resting-state functional connectivity. Thirty-four delirious patients and 38 non-delirious controls were scanned for resting-state functional MRI. Seed-based connectivity of the suprachiasmatic nucleus was compared between the groups. In delirious patients functional connectivity from the circadian clock was increased to the dorsal anterior cingulate cortex and decreased to the posterior cingulate cortex, parahippocampal gyrus, cerebellum, and thalamus...
April 4, 2017: Psychiatry Research
https://www.readbyqxmd.com/read/28377630/katp-channels-mediate-differential-metabolic-responses-to-glucose-shortage-of-the-dorsomedial-and-ventrolateral-oscillators-in-the-central-clock
#10
Jyh-Jeen Yang, Ruo-Ciao Cheng, Pi-Cheng Cheng, Yi-Chi Wang, Rong-Chi Huang
The suprachiasmatic nucleus (SCN) central clock comprises two coupled oscillators, with light entraining the retinorecipient vasoactive intestinal peptide (VIP)-positive ventrolateral oscillator, which then entrains the arginine vasopressin (AVP)-positive dorsomedial oscillator. While glucose availability is known to alter photic entrainment, it is unclear how the SCN neurones respond to metabolic regulation and whether the two oscillators respond differently. Here we show that the ATP-sensitive K(+) (KATP) channel mediates differential responses to glucose shortage of the two oscillators...
April 4, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28374011/suprachiasmatic-nucleus-interaction-with-the-arcuate-nucleus-essential-for-organizing-physiological-rhythms
#11
Frederik N Buijs, Mara Guzmán-Ruiz, Luis León-Mercado, Mari Carmen Basualdo, Carolina Escobar, Andries Kalsbeek, Ruud M Buijs
The suprachiasmatic nucleus (SCN) is generally considered the master clock, independently driving all circadian rhythms. We recently demonstrated the SCN receives metabolic and cardiovascular feedback adeptly altering its neuronal activity. In the present study, we show that microcuts effectively removing SCN-arcuate nucleus (ARC) interconnectivity in Wistar rats result in a loss of rhythmicity in locomotor activity, corticosterone levels, and body temperature in constant dark (DD) conditions. Elimination of these reciprocal connections did not affect SCN clock gene rhythmicity but did cause the ARC to desynchronize...
March 2017: ENeuro
https://www.readbyqxmd.com/read/28371363/diurnal-expression-of-proteins-in-the-retina-of-the-blind-cone-rod-homeobox-crx-mouse-and-the-129-sv-mouse-a-proteomic-study
#12
Morten Møller, Martin Fredensborg Rath, Maja Ludvigsen, Bent Honoré, Henrik Vorum
PURPOSE: The vertebrate retina contains a circadian clock participating in adaptations to day and night vision. This peripheral clock is independent of the master clock in the suprachiasmatic nucleus (SCN). The retinal clock is located in several cell types, including the photoreceptors. To investigate the role of the circadian clock of the photoreceptor cells in regulation of retinal protein rhythms, we analysed diurnal protein expression in the photoreceptor-deficient cone-rod homeobox knockout mouse (Crx(-/-) ) and the 129/Sv mouse...
March 28, 2017: Acta Ophthalmologica
https://www.readbyqxmd.com/read/28367335/circadian-plasticity-of-mammalian-inhibitory-interneurons
#13
REVIEW
Malgorzata Jasinska, Elzbieta Pyza
Inhibitory interneurons participate in all neuronal circuits in the mammalian brain, including the circadian clock system, and are indispensable for their effective function. Although the clock neurons have different molecular and electrical properties, their main function is the generation of circadian oscillations. Here we review the circadian plasticity of GABAergic interneurons in several areas of the mammalian brain, suprachiasmatic nucleus, neocortex, hippocampus, olfactory bulb, cerebellum, striatum, and in the retina...
2017: Neural Plasticity
https://www.readbyqxmd.com/read/28348447/fos-expression-in-the-olfactory-pathway-of-high-and-low-sexually-performing-rams-exposed-to-urine-from-estrous-or-ovariectomized-ewes
#14
A J Mirto, K J Austin, V A Uthlaut, C E Roselli, B M Alexander
Exposure to estrous ewe urine stimulates investigation and mounting activity in sexually active but not sexually inactive rams. It was hypothesized sexual indifference may result from an inability to detect olfactory cues or an interruption of the pathway from detection of the olfactory stimulus to the motor response. Sexually active (n=4) and inactive (n=3) rams were exposed to urine from estrous ewes. An additional group of sexually active rams (n=3) were exposed to urine from ovariectomized ewes. Rams were exsanguinated following 1 h of exposure to stimulus...
January 2017: Applied Animal Behaviour Science
https://www.readbyqxmd.com/read/28348112/hypophysectomy-abolishes-rhythms-in-rat-thyroid-hormones-but-not-in-the-thyroid-clock
#15
Jan Fahrenkrug, Birgitte Georg, Jens Hannibal, Henrik Løvendahl Jørgensen
The endocrine body rhythms including the hypothalamic-pituitary-thyroid axis seem to be regulated by the circadian timing system, and daily rhythmicity of circulating thyroid stimulating hormone (TSH) is well-established. The circadian rhythms are generated by endogenous clocks in the central brain oscillator located in the hypothalamic suprachiasmatic nucleus (SCN) as well as multiple peripheral clocks, but information on the existence and function of a thyroid clock is limited. The molecular machinery in all clock cells is composed of a number of clock genes and their gene products connected by autoregulatory feedback loops...
March 27, 2017: Journal of Endocrinology
https://www.readbyqxmd.com/read/28343966/astrocytes-regulate-daily-rhythms-in-the-suprachiasmatic-nucleus-and-behavior
#16
Chak Foon Tso, Tatiana Simon, Alison C Greenlaw, Tanvi Puri, Michihiro Mieda, Erik D Herzog
Astrocytes are active partners in neural information processing [1, 2]. However, the roles of astrocytes in regulating behavior remain unclear [3, 4]. Because astrocytes have persistent circadian clock gene expression and ATP release in vitro [5-8], we hypothesized that they regulate daily rhythms in neurons and behavior. Here, we demonstrated that daily rhythms in astrocytes within the mammalian master circadian pacemaker, the suprachiasmatic nucleus (SCN), determine the period of wheel-running activity. Ablating the essential clock gene Bmal1 specifically in SCN astrocytes lengthened the circadian period of clock gene expression in the SCN and in locomotor behavior...
April 3, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28337174/regulation-of-mammalian-physiology-by-interconnected-circadian-and-feeding-rhythms
#17
REVIEW
Florian Atger, Daniel Mauvoisin, Benjamin Weger, Cédric Gobet, Frédéric Gachon
Circadian clocks are endogenous timekeeping systems that adapt in an anticipatory fashion the physiology and behavior of most living organisms. In mammals, the master pacemaker resides in the suprachiasmatic nucleus and entrains peripheral clocks using a wide range of signals that differentially schedule physiology and gene expression in a tissue-specific manner. The peripheral clocks, such as those found in the liver, are particularly sensitive to rhythmic external cues like feeding behavior, which modulate the phase and amplitude of rhythmic gene expression...
2017: Frontiers in Endocrinology
https://www.readbyqxmd.com/read/28332018/seasonal-loss-and-resumption-of-circadian-rhythms-in-hibernating-arctic-ground-squirrels
#18
Cory T Williams, Maya Radonich, Brian M Barnes, C Loren Buck
Circadian clocks are near universal among organisms and play a key role in coordinating physiological and metabolic functions to anticipate or coincide with predictable daily changes in the physical and social environment. However, whether circadian rhythms persist and are functionally important during hibernation in all mammals is currently unclear. We examined whether circadian rhythms of body temperature (T b) persist during multi-day, steady-state torpor and investigated the association between timing of animal emergence, exposure to light, and resumption of activity and T b rhythms in free-living and captive male arctic ground squirrels...
March 22, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28331994/daily-socs1-rhythms-alter-with-aging-differentially-in-peripheral-clocks-in-male-wistar-rats-therapeutic-effects-of-melatonin
#19
Ch Vinod, Anita Jagota
Suprachiasmatic nucleus (SCN) in synchronization with the peripheral clocks regulates the temporal oscillations leading to overt rhythms. Aging leads to attenuation of such circadian regulation, accompanied by increased inflammatory mediators prevalently the cytokines. Suppressors of cytokine signaling (SOCS) family of proteins such as SOCS 1, 3 and cytokine-inducible SH2-containing protein (CIS) negatively regulate the cytokine signaling pathway. The role of SOCS1 in aging and circadian system is obscure. We therefore studied the daily rhythms of rSocs1 mRNA expression at Zeitgeber time (ZT) -0, 6, 12 and 18 in peripheral clocks such as liver, kidney, intestine and heart of 3, 12 and 24 months (m) old male Wistar rats...
March 22, 2017: Biogerontology
https://www.readbyqxmd.com/read/28326909/resynchronization-dynamics-reveal-that-the-ventral-entrains-the-dorsal-suprachiasmatic-nucleus
#20
Stephanie R Taylor, Thomas J Wang, Daniel Granados-Fuentes, Erik D Herzog
Although the suprachiasmatic nucleus (SCN) has long been considered the master circadian clock in mammals, the topology of the connections that synchronize daily rhythms among SCN cells is not well understood. We combined experimental and computational methods to infer the directed interactions that mediate circadian synchrony between regions of the SCN. We analyzed PERIOD2 (PER2) expression from SCN slices during and after treatment with tetrodotoxin, allowing us to map connections as cells resynchronized their daily cycling following blockade and restoration of cell-cell communication...
February 2017: Journal of Biological Rhythms
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