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suprachiasmatic nucleus

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...
October 22, 2016: Brain, Behavior and Evolution
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
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
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
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 is unknown...
October 14, 2016: European Journal of Neuroscience
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-operated 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
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
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 (SCN), a hypothalamic region that receives direct photic input. The SCN then entrains additional oscillators in the periphery. Circadian rhythms are maintained by a molecular transcriptional feedback loop, of which BMAL1 is a key member. Disruption of circadian rhythms by deletion of the BMAL1 gene (Bmal1 KO) induces a variety of disease states, including infertility in males, due to unidentified mechanisms...
October 5, 2016: Endocrinology
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
Sahar Farajnia, Johanna H Meijer, Stephan Michel
One feature of the mammalian circadian clock, situated in the suprachiasmatic nucleus (SCN), is its ability to measure day length and thereby contribute to the seasonal adaptation of physiology and behavior. The timing signal from the SCN, namely the 24 hr pattern of electrical activity, is adjusted according to the photoperiod being broader in long days and narrower in short days. Vasoactive intestinal peptide and gamma-aminobutyric acid play a crucial role in intercellular communication within the SCN and contribute to the seasonal changes in phase distribution...
October 2016: ASN Neuro
Shery Goril, Dora Zalai, Louise Scott, Colin M Shapiro
OBJECTIVES: Caregivers describe significant sleep disturbances in the vast majority of children and adolescents, which is diagnosed as fetal alcohol spectrum disorders (FASD), but objective data on sleep disorders in this population are almost completely lacking. Animal models suggest that intrauterine alcohol exposure may disrupt sleep wake patterns, cause sleep fragmentation, and specifically affect the suprachiasmatic nucleus, thus disrupting melatonin secretion. The objective of this pioneering study was to evaluate sleep and melatonin abnormalities in children with FASD using objective, gold-standard measures...
July 2016: Sleep Medicine
Deyra A Ramírez, Elizabeth Vieyra, Aldo I González, Carolina Morán, Roberto Domínguez, Leticia Morales-Ledesma
The aims of the present study were to analyze if the superior ovarian nerve (SON) plays a role in the neural signals from suprachiasmatic nucleus (SCN) that lead to ovulation and ovarian steroids secretion on proestrus day. Rats on proestrus day were treated at 11.00 to 11.30 or 17.00 to 17.30 hours with 1 of the 3 experimental procedures (1) unilateral or bilateral SON sectioning, (2) unilateral or bilateral injury to the SCN, or (3) unilateral injury to the SCN followed by unilateral sectioning of the SON ipsilateral to the treated SCN...
September 29, 2016: Reproductive Sciences
C Gizowski, C Zaelzer, C W Bourque
Circadian rhythms have evolved to anticipate and adapt animals to the constraints of the earth's 24-hour light cycle. Although the molecular processes that establish periodicity in clock neurons of the suprachiasmatic nucleus (SCN) are well understood, the mechanisms by which axonal projections from the central clock drive behavioural rhythms are unknown. Here we show that the sleep period in mice (Zeitgeber time, ZT0-12) is preceded by an increase in water intake promoted entirely by the central clock, and not motivated by physiological need...
September 28, 2016: Nature
Satish Sen, Hélène Raingard, Stéphanie Dumont, Andries Kalsbeek, Patrick Vuillez, Etienne Challet
Restricted feeding during the resting period causes pronounced shifts in a number of peripheral clocks, but not the central clock in the suprachiasmatic nucleus (SCN). By contrast, daily caloric restriction impacts also the light-entrained SCN clock, as indicated by shifted oscillations of clock (PER1) and clock-controlled (vasopressin) proteins. To determine if these SCN changes are due to the metabolic or timing cues of the restricted feeding, mice were challenged with an ultradian 6-meals schedule (1 food access every 4 h) to abolish the daily periodicity of feeding...
September 26, 2016: Chronobiology International
Donají Chi-Castañeda, Arturo Ortega
Circadian rhythms are periodic patterns in biological processes that allow the organisms to anticipate changes in the environment. These rhythms are driven by the suprachiasmatic nucleus (SCN), the master circadian clock in vertebrates. At a molecular level, circadian rhythms are regulated by the so-called clock genes, which oscillate in a periodic manner. The protein products of clock genes are transcription factors that control their own and other genes' transcription, collectively known as "clock-controlled genes...
October 2016: ASN Neuro
Ishfaq Ali, Shobha Bhargava
Neuropeptide Y (NPY) has emerged as a novel peptide to antagonize various physiological consequences of stress within a mammalian brain. Hypoxia induced neuropeptide Y release in mammalian systems is well established. However, the possible role of NPY in regulating the effects of oxygen variation in lower vertebrates has not been investigated. We have studied the distribution and neuro-anatomical expression of NPY in the brain of Euphlyctus cyanophlyctus tadpoles, exposed to normal and reduced oxygen levels using immunohistochemistry...
September 20, 2016: General and Comparative Endocrinology
Isa Kolbe, Jana Husse, Gabriela Salinas, Thomas Lingner, Mariana Astiz, Henrik Oster
The circadian master pacemaker in the suprachiasmatic nucleus (SCN) orchestrates peripheral clocks in various organs and synchronizes them with external time, including those in adipose tissue, which displays circadian oscillations in various metabolic and endocrine outputs. Because our knowledge about the instructive role of the SCN clock on peripheral tissue function is based mainly on SCN lesion studies, we here used an alternative strategy employing the Cre/loxP system to functionally delete the SCN clock in mice...
September 20, 2016: Journal of Biological Rhythms
Koliane Ouk, Juliet Aungier, A Jennifer Morton
Huntington's disease (HD) is a progressive genetic neurodegenerative disorder characterised by motor and cognitive deficits, as well as sleep and circadian abnormalities. In the R6/2 mouse, a fragment model of HD, rest-activity rhythms controlled by the suprachiasmatic nucleus disintegrate completely by 4months of age. Rhythms driven by a second circadian oscillator, the methamphetamine-sensitive circadian oscillator (MASCO), are disrupted even earlier, and cannot be induced after 2months of age. Here, we studied the effect of the HD mutation on the expression of MASCO-driven rhythms in a more slowly developing, genetically relevant mouse model of HD, the Q175 'knock-in' mouse...
September 16, 2016: Experimental Neurology
Jun J Nakano, Kimiko Shimizu, Shigeki Shimba, Yoshitaka Fukada
While disruption of the circadian clock triggers a spectrum of affective abnormalities, how the clock regulates mammalian emotionality remains unclear. Here, we characterized the time-of-day-dependent regulation of mouse anxiety-like behaviors. We show that anxiety-like behaviors are expressed in a circadian manner in mice and demonstrate that the clock machineries in the dorsal telencephalon (dTel) are required for the time-of-day-dependent regulation of anxiety-like behaviors. We identify suprachiasmatic nucleus circadian oscillatory protein (SCOP/PHLPP1β) as an essential intracellular signaling molecule mediating this temporal regulation downstream of the clock...
2016: Scientific Reports
Maria Angeles Bonmati-Carrion, Konstanze Hild, Cheryl Isherwood, Stephen J Sweeney, Victoria L Revell, Debra J Skene, Maria Angeles Rol, Juan Antonio Madrid
Intrinsically photosensitive retinal ganglion cells (ipRGCs), whose photopigment melanopsin has a peak of sensitivity in the short wavelength range of the spectrum, constitute a common light input pathway to the olivary pretectal nucleus (OPN), the pupillary light reflex (PLR) regulatory centre, and to the suprachiasmatic nuclei (SCN), the major pacemaker of the circadian system. Thus, evaluating PLR under short wavelength light (λmax ≤ 500 nm) and creating an integrated PLR parameter, as a possible tool to indirectly assess the status of the circadian system, becomes of interest...
2016: PloS One
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