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suprachiasmatic nucleus

Norman Atkins, Shifang Ren, Nathan G Hatcher, Penny W Burgoon, Jennifer W Mitchell, Jonathan V Sweedler, Martha U Gillette
Daily oscillations of brain and body states are under complex temporal modulation by environmental light and the hypothalamic suprachiasmatic nucleus (SCN), the master circadian clock. To better understand mediators of differential temporal modulation, we characterize neuropeptide releasate profiles by non-selective capture of secreted neuropeptides in an optic nerve-horizontal SCN brain slice model. Releasates are collected following electrophysiological stimulation of the optic nerve/retinohypothalamic tract under conditions that alter the phase of SCN activity state...
June 14, 2018: ACS Chemical Neuroscience
Monika Dmitrzak-Weglarz, Edyta Reszka
Circadian rhythm alterations resulting in disturbed sleep and disturbed melatonin secretion are flagship features of depression. Melatonin, known as a hormone of darkness, is secreted by the pineal gland located near to the center of the brain between the two hemispheres. Melatonin has an antidepressant effect by maintaining the body's circadian rhythm, by regulating the pattern of expression of the clock genes in the suprachiasmatic nucleus (SCN) and modifying the key genes of serotoninergic neurotransmission that are linked with a depressive mood...
June 13, 2018: Neuropsychobiology
Shuhui Ma, Zixu Wang, Jing Cao, Yulan Dong, Yaoxing Chen
The avian circadian system is a complex of mutually coupled pacemakers residing in pineal gland, retina and suprachiasmatic nucleus. In this study, the self-regulation mechanism of pineal circadian rhythm was investigated by culturing chick primary pinealocytes exposed to red light (RL), green light (GL), blue light (BL), white light (WL) and constant darkness (DD), respectively. All illuminations were set up with a photoperiod of 12 light: 12 dark. The 24-h expression profiles of seven core clock genes (cBmal1/2, cClock, cCry1/2, and cPer2/3), cAanat and melatonin showed significant circadian oscillation in all groups, except for the loss of cCry1 rhythm in BL...
June 13, 2018: Photochemistry and Photobiology
Jennifer Y Li, Tiffany M Schmidt
In addition to its well-known role in pattern vision, light influences a wide range of non-image forming, subconscious visual behaviors including circadian photoentrainment, sleep, mood, learning, and the pupillary light reflex. Each of these behaviors is thought to require input from the M1 subtype of melanopsin-expressing, intrinsically photosensitive retinal ganglion cell (ipRGC). Recent work has demonstrated that the M1 subtype of ipRGC can be further subdivided based on expression of the transcription factor Brn3b...
June 11, 2018: Journal of Comparative Neurology
Denis Matrov, Tanel Kaart, Laurence Lanfumey, Rafael Maldonado, Trevor Sharp, Rosa M Tordera, Paul A Kelly, Bill Deakin, Jaanus Harro
The psychopathology of depression is highly complex and the outcome of studies on animal models is divergent. In order to find brain regions that could be metabolically distinctively active across a variety of mouse depression models and to compare the interconnectivity of brain regions of wild-type and such genetically modified mice, histochemical mapping of oxidative metabolism was performed by the measurement of cytochrome oxidase activity. We included mice with the heterozygous knockout of the vesicular glutamate transporter (VGLUT1 -/+ ), full knockout of the cannabinoid 1 receptor (CB1-/- ), an anti-sense knockdown of the glucocorticoid receptor (GRi) and overexpression of the human 5-hydroxytryptamine transporter (h5-HTT)...
June 7, 2018: Behavioural Brain Research
Mario Caba, Jorge Mendoza
In mammals, the suprachiasmatic nucleus (SCN), the master circadian clock, is mainly synchronized to the environmental light/dark cycle. SCN oscillations are maintained by a molecular clockwork in which certain genes, Period 1-2, Cry1-2, Bmal1, and Clock, are rhythmically expressed. Disruption of these genes leads to a malfunctioning clockwork and behavioral and physiological rhythms are altered. In addition to synchronization of circadian rhythms by light, when subjects are exposed to food for a few hours daily, behavioral and physiological rhythms are entrained to anticipate mealtime, even in the absence of the SCN...
2018: Frontiers in Endocrinology
Nelyane N M Santana, Marília A S Barros, Helder H A Medeiros, Melquisedec A D Santana, Lara L Silva, Paulo L A G Morais, Fernando V L Ladd, Jeferson S Cavalcante, Ruthnaldo R M Lima, Judney C Cavalcante, Miriam S M O Costa, Rovena C J G Engelberth, Expedito S Nascimento
In mammals, the suprachiasmatic nucleus (SCN) and the intergeniculate leaflet (IGL) are the main components of the circadian timing system. The SCN, classically known as the master circadian clock, generates rhythms and synchronizes them to environmental cues. The IGL is a key structure that modulates SCN activity. Strategies on the use of time by animals can provide important clues about how some species are adapted to competitive process in nature. Few studies have provided information about temporal niche in bats with special attention on the neural substrate underlies circadian rhythms...
2018: Frontiers in Neuroanatomy
Yulin Chen, Yoshiaki Yamaguchi, Toru Suzuki, Masao Doi, Hitoshi Okamura
Jet-lag symptoms arise from temporal misalignment between the internal circadian clock and external solar time when traveling across multiple time zones. Light is known as a strong timing cue of the circadian clock. We here examined the effect of daily light on the process of jet lag by detecting c-Fos expression in the master clock neurons in the suprachiasmatic nucleus (SCN) under 8-hr phase-advanced jet lag condition. In WT mice, c-Fos-immunoreactivity was found at 1-2 hours on the first day after light/dark (LD) phase-advance...
April 27, 2018: Acta Histochemica et Cytochemica
Martina Pfeffer, Zuzana Zimmermann, Suzana Gispert, Georg Auburger, Horst-Werner Korf, Charlotte von Gall
Parkinson's disease (PD) is characterized by distinct motor and non-motor symptoms. Sleep disorders are the most frequent and challenging non-motor symptoms in PD patients, and there is growing evidence that they are a consequence of disruptions within the circadian system. PD is characterized by a progressive degeneration of the dorsal vagal nucleus and midbrain dopaminergic neurons together with an imbalance of many other neurotransmitters. Mutations in α-synuclein (SNCA), a protein modulating SNARE complex-dependent neurotransmission, trigger dominantly inherited PD variants and sporadic cases of PD...
June 3, 2018: International Journal of Molecular Sciences
Rudiger Hardeland
Several recent developments in melatonin research deserve attention and divulgation. The role of melatonin in the brain has been extended to its synthesis in the cerebellum as a response to inflammation, findings that exceed the earlier demonstration of aralkylamine N-acetyltransferase expression. The release of melatonin via the pineal recess into the third ventricle appears to be more important than previously believed and has been discussed as a strong direct signal to the suprachiasmatic nucleus. The mitochondrial role of melatonin has been substantially extended by the demonstration of the melatonin receptor MT1 in this organelle and evidence for melatonin synthesis in mammalian mitochondria, in addition to the previously shown uptake into these organelles...
May 30, 2018: Central Nervous System Agents in Medicinal Chemistry
Aldo Giudice, Anna Crispo, Maria Grimaldi, Andrea Polo, Sabrina Bimonte, Mario Capunzo, Alfonso Amore, Giovanni D'Arena, Pellegrino Cerino, Alfredo Budillon, Gerardo Botti, Susan Costantini, Maurizio Montella
In mammals, a master clock is located within the suprachiasmatic nucleus (SCN) of the hypothalamus, a region that receives input from the retina that is transmitted by the retinohypothalamic tract. The SCN controls the nocturnal synthesis of melatonin by the pineal gland that can influence the activity of the clock's genes and be involved in the inhibition of cancer development. On the other hand, in the literature, some papers highlight that artificial light exposure at night (LAN)-induced circadian disruptions promote cancer...
May 29, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Pi-Cheng Cheng, Yi-Chi Wang, Ya-Shuan Chen, Ruo-Ciao Cheng, Jyh-Jeen Yang, Rong-Chi Huang
BACKGROUND: Transmembrane Ca2+ influx is critical for molecular rhythmicity, metabolic activity, and neuropeptide release in the central clock of the suprachiasmatic nucleus (SCN). We previously reported that both the Na+ /Ca2+ exchanger (NCX) and mitochondria play a role in regulating intracellular Ca2+ homeostasis in the rat SCN neurons. Here we present evidence to show differential regulation by NCX and mitochondria of nimodipine-sensitive and -insensitive Ca2+ influx. METHODS: Ratiometric Ca2+ imaging was used to measure change in [Ca2+ ]i and patch clamp recordings to study spontaneous firing, membrane potential, and voltage-dependent Ca2+ channels in neurons from reduced SCN slice preparations...
May 22, 2018: Journal of Biomedical Science
Ajda Yilmaz, Andries Kalsbeek, Ruud M Buijs
The present study investigates the circadian behavior of spontaneously hypertensive rats (SHRs) during the pre-hypertensive and hypertensive stage, with the aim to gain insight into whether observed changes in the functionality of suprachiasmatic nucleus (SCN) in the hypertensive state are cause or consequence of hypertension. Four types of animals were used in this study: (1) SHRs which develop hypertension genetically; (2) their normotensive controls, Wistar Kyoto rats (WKYs); (3) Wistar rats whereby hypertension was surgically induced (2 Kidney 1 Clamp (2K1C) method); and (4) sham-operated control Wistar rats...
May 22, 2018: Chronobiology International
Christopher M Depner, Edward L Melanson, Andrew W McHill, Kenneth P Wright
Proteomics holds great promise for understanding human physiology, developing health biomarkers, and precision medicine. However, how much the plasma proteome varies with time of day and is regulated by the master circadian suprachiasmatic nucleus brain clock, assessed here by the melatonin rhythm, is largely unknown. Here, we assessed 24-h time-of-day patterns of human plasma proteins in six healthy men during daytime food intake and nighttime sleep in phase with the endogenous circadian clock (i.e., circadian alignment) versus daytime sleep and nighttime food intake out of phase with the endogenous circadian clock (i...
May 21, 2018: Proceedings of the National Academy of Sciences of the United States of America
A H O Olde Engberink, J H Meijer, S Michel
One of the principal neurotransmitters of the central nervous system is GABA. In the adult brain, GABA is predominantly inhibitory, but there is growing evidence indicating that GABA can shift to excitatory action depending on environmental conditions. In the mammalian central circadian clock of the suprachiasmatic nucleus (SCN) GABAergic activity shifts from inhibition to excitation when animals are exposed to long day photoperiod. The polarity of the GABAergic response (inhibitory versus excitatory) depends on the GABA equilibrium potential determined by the intracellular Cl- concentration ([Cl- ]i )...
May 18, 2018: Neuropharmacology
Sandra Crnko, Martin Cour, Linda W Van Laake, Sandrine Lecour
The master mammalian circadian clock (i.e. central clock), located in the suprachiasmatic nucleus of the hypothalamus, orchestrates the synchronization of the daily behavioural and physiological rhythms to better adapt the organism to the external environment in an anticipatory manner. This central clock is entrained by a variety of signals, the best established being light and food. However, circadian cycles are not simply the consequences of these two cues but are generated by endogenous circadian clocks...
May 17, 2018: Vascular Pharmacology
Jorge Mendoza, Hester C van Diepen, Rob Rodrigues Pereira, Johanna H Meijer
People suffering of attention-deficit/hyperactivity disorder (ADHD) and treated with the psychostimulant methylphenidate (MPH) show sleep-wake cycle and daily rhythm alterations despite the beneficial effects of MPH on behavioral symptoms (i.e., hyperactivity, attention). In nocturnal rodents (i.e., mice), chronic exposure to MPH alters the neural activity of the circadian clock in the suprachiasmatic nucleus (SCN), behavioral rhythms, and the sleep-wake cycle. Here, we studied the effects of MPH on daily rhythms of behavior and body temperature of the diurnal rodent Arvicanthis ansorgei...
May 18, 2018: Psychopharmacology
Sunghyon Kyeong, Jung Eun Shin, Kyu Hyun Yang, Woo Suk Lee, Tae-Sub Chung, Jae-Jin Kim
Elderly adults are more likely to develop delirium after major surgery, but there is limited knowledge of the vulnerability for postoperative delirium. In this study, we aimed to identify neural predisposing factors for postoperative delirium and develop a prediction model for estimating an individual's probability of postoperative delirium. Among 57 elderly participants with femoral neck fracture, 25 patients developed postoperative delirium and 32 patients did not. We preoperatively obtained data for clinical assessments, anatomical MRI, and resting-state functional MRI...
May 15, 2018: Scientific Reports
Michael G Moldavan, Patricia J Sollars, Michael R Lasarev, Charles N Allen, Gary E Pickard
Intrinsically photosensitive retinal ganglion cells (ipRGCs) innervate the hypothalamic suprachiasmatic nucleus (SCN), a circadian oscillator that functions as a biological clock. ipRGCs use vesicular glutamate transporter 2 (vGlut2) to package glutamate into synaptic vesicles and light-evoked resetting of the SCN circadian clock is widely attributed to ipRGC glutamatergic neurotransmission. Pituitary adenylate cyclase-activating polypeptide (PACAP) is also packaged into vesicles in ipRGCs and PACAP may be coreleased with glutamate in the SCN...
May 2018: ENeuro
Chidambaram Ramanathan, Nimish D Kathale, Dong Liu, Choogon Lee, David A Freeman, John B Hogenesch, Ruifeng Cao, Andrew C Liu
The circadian clock coordinates physiology and metabolism. mTOR (mammalian/mechanistic target of rapamycin) is a major intracellular sensor that integrates nutrient and energy status to regulate protein synthesis, metabolism, and cell growth. Previous studies have identified a key role for mTOR in regulating photic entrainment and synchrony of the central circadian clock in the suprachiasmatic nucleus (SCN). Given that mTOR activities exhibit robust circadian oscillations in a variety of tissues and cells including the SCN, here we continued to investigate the role of mTOR in orchestrating autonomous clock functions in central and peripheral circadian oscillators...
May 11, 2018: PLoS Genetics
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