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suprachiasmatic nucleus

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https://www.readbyqxmd.com/read/28629848/a-novel-intrinsic-electroretinogram-response-in-isolated-mouse-retina
#1
Motoharu Takao, Yumi Fukuda, Takeshi Morita
Since the discovery of intrinsic photosensitive retinal ganglion cell (ipRGC) was reported in 2002, many features specific to this cell type have been described. However, scare information is available on the retinographic components directly reflecting ipRGC activity. In this study, we identified the electroretinogram (microERG) that reflects the photoresponses by ipRGCs in ex vivo preparations of the mouse retina, in which classical photoreceptors (cones and rods) were ablated mechanically and photochemically...
June 16, 2017: Neuroscience
https://www.readbyqxmd.com/read/28623226/entraining-to-the-polar-day-circadian-rhythms-in-arctic-ground-squirrels
#2
Cory T Williams, Brian M Barnes, Lily Yan, C Loren Buck
Circadian systems are principally entrained to 24h light/dark cycles, but this cue is seasonally absent in polar environments. Although some resident polar vertebrates have weak circadian clocks and are seasonally arrhythmic, the arctic ground squirrel (AGS) maintains daily rhythms of physiology and behavior throughout the summer, which includes six weeks of constant daylight. Here, we show that persistent daily rhythms in AGS are maintained through a circadian system that readily entrains to the polar day yet remains insensitive to entrainment by rapid light-dark transitions, which AGS generate naturally due to their semi-fossorial behavior...
June 16, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28616754/sexually-dimorphic-distribution-of-prokr2-neurons-revealed-by-the-prokr2-cre-mouse-model
#3
Zaid Mohsen, Hosung Sim, David Garcia-Galiano, Xingfa Han, Nicole Bellefontaine, Thomas L Saunders, Carol F Elias
Prokineticin receptor 2 (PROKR2) is predominantly expressed in the mammalian central nervous system. Loss-of-function mutations of PROKR2 in humans are associated with Kallmann syndrome due to the disruption of gonadotropin releasing hormone neuronal migration and deficient olfactory bulb morphogenesis. PROKR2 has been also implicated in the neuroendocrine control of GnRH neurons post-migration and other physiological systems. However, the brain circuitry and mechanisms associated with these actions have been difficult to investigate mainly due to the widespread distribution of Prokr2-expressing cells, and the lack of animal models and molecular tools...
June 14, 2017: Brain Structure & Function
https://www.readbyqxmd.com/read/28608287/increased-glutamic-acid-decarboxylase-expression-in-the-hypothalamic-suprachiasmatic-nucleus-in-depression
#4
Xueyan Wu, Rawien Balesar, Jing Lu, Sahar Farajnia, Qiongbin Zhu, Manli Huang, Ai-Min Bao
In depression, disrupted circadian rhythms reflect abnormalities in the central circadian pacemaker, the hypothalamic suprachiasmatic nucleus (SCN). Although many SCN neurons are said to be GABAergic, it was not yet known whether and how SCN GABA changes occur in the SCN in depression. We, therefore, studied GABA in the SCN in relation to the changes in arginine vasopressin (AVP), which is one of the major SCN output systems. Postmortem hypothalamus specimens of 13 subjects suffering from depression and of 13 well-matched controls were collected...
June 12, 2017: Brain Structure & Function
https://www.readbyqxmd.com/read/28608154/neural-control-of-daily-and-seasonal-timing-of-songbird-migration
#5
Tyler J Stevenson, Vinod Kumar
Bird migration is one of most salient annual events in nature. It involves predictable seasonal movements between breeding and non-breeding habitats. Both circadian and circannual clocks are entrained by photoperiodic cues and time daily and seasonal changes in migratory physiology and behavior. This mini-review provides an update on daily and seasonal rhythms of migratory behavior, and examines the neuroendocrine and molecular pathways involved in the timing of migration in songbirds. Recent findings have identified key neural substrates, and suggest the involvement of multiple neuroendocrine regulatory systems in controlling seasonal states in migrants...
June 12, 2017: Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology
https://www.readbyqxmd.com/read/28596466/-clocks-behavior-and-cognition
#6
Akinori Futamura, Azusa Shiromaru, Takeshi Kuroda, Motoyasu Honma, Ryuta Kinno, Kenjiro Ono, Mitsuru Kawamura
The nerve center responsible for controlling our circadian rhythm is located in a cluster of cells known as the suprachiasmatic nucleus in the hypothalamus. Various physiological functions such as sleep, arousal, blood pressure, body temperature, and hormone secretion are regulated in a 24-hour rhythm by this circuit. Somatic cells of other organs have a peripheral clock gene and by synchronizing the rhythm of the central and peripheral clocks, it is possible to live a healthy life. Due to aging and degenerative disease, circadian rhythm gradually collapses...
June 2017: Brain and Nerve, Shinkei Kenkyū No Shinpo
https://www.readbyqxmd.com/read/28588500/temporal-expression-patterns-of-clock-genes-and-aquaporin-5-anoctamin-1-in-rat-submandibular-gland-cells
#7
Ryouichi Satou, Masaki Sato, Maki Kimura, Yoichi Ishizuka, Masakazu Tazaki, Naoki Sugihara, Yoshiyuki Shibukawa
Circadian rhythms are essential for health and regulate various physiological functions. These rhythms are regulated by a negative-feedback loop involving clock genes in the suprachiasmatic nucleus (SCN) and peripheral tissues. The rate of secretion of salivary substances, ions, and water follows a circadian rhythm, however, the relationship between the molecular mechanism of salivary secretion and peripheral circadian rhythm is not yet clear. Anoctamin 1 (ANO1, also known as TMEM16A) and Aquaporin 5 (AQP5) play an important role in the transport of ions and water in the submandibular glands (SGs)...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28585194/circadian-rhythms-in-diet-induced-obesity
#8
Atilla Engin
The biological clocks of the circadian timing system coordinate cellular and physiological processes and synchronizes these with daily cycles, feeding patterns also regulates circadian clocks. The clock genes and adipocytokines show circadian rhythmicity. Dysfunction of these genes are involved in the alteration of these adipokines during the development of obesity. Food availability promotes the stimuli associated with food intake which is a circadian oscillator outside of the suprachiasmatic nucleus (SCN)...
2017: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/28577110/daily-chronomics-of-proteomic-profile-in-aging-and-rotenone-induced-parkinson-s-disease-model-in-male-wistar-rat-and-its-modulation-by-melatonin
#9
Anita Jagota, Ushodaya Mattam
Aging is associated with changes in several basic parameters of circadian timing system (CTS) in mammals leading to circadian dysfunction. We had reported earlier that upon aging and in rotenone induced Parkinson's disease (RIPD) rat model there were significant alterations in the core clock genes expression levels and daily pulses. To identify biomarkers of aging and PD chronomics of proteomic day-night profiles in suprachiasmatic nucleus (SCN), pineal and substantia nigra (SN) in 3 month (m), 12, 24 m and RIPD rat model were studied at two time points i...
June 2, 2017: Biogerontology
https://www.readbyqxmd.com/read/28576728/cellular-circadian-oscillators-in-the-suprachiasmatic-nucleus-remain-coupled-in-the-absence-of-connexin-36
#10
Tanja Diemer, Dominic Landgraf, Takako Noguchi, Haiyun Pan, Jose L Moreno, David K Welsh
In mammals, the master circadian clock resides in the suprachiasmatic nucleus (SCN). The SCN is characterized by robust circadian oscillations of clock gene expression and neuronal firing. The synchronization of circadian oscillations among individual cells in the SCN is attributed to intercellular coupling. Previous studies have shown that gap junctions, specifically those composed of connexin-36 (Cx36) subunits, are required for coupling of electrical firing among SCN neurons at a time scale of milliseconds...
May 31, 2017: Neuroscience
https://www.readbyqxmd.com/read/28575207/moran-s-i-quantifies-spatio-temporal-pattern-formation-in-neural-imaging-data
#11
Christoph Schmal, Jihwan Myung, Hanspeter Herzel, Grigory Bordyugov
Motivation: Neural activities of the brain occur through the formation of spatio-temporal patterns. In recent years, macroscopic neural imaging techniques have produced a large body of data on these patterned activities, yet a numerical measure of spatio-temporal coherence has often been reduced to the global order parameter, which does not uncover the degree of spatial correlation. Here, we propose to use the spatial autocorrelation measure Moran's I, which can be applied to capture dynamic signatures of spatial organization...
May 31, 2017: Bioinformatics
https://www.readbyqxmd.com/read/28560311/acute-knockdown-of-kv4-1-regulates-repetitive-firing-rates-and-clock-gene-expression-in-the-suprachiasmatic-nucleus-and-daily-rhythms-in-locomotor-behavior
#12
Tracey O Hermanstyne, Daniel Granados-Fuentes, Rebecca L Mellor, Erik D Herzog, Jeanne M Nerbonne
Rapidly activating and inactivating A-type K(+) currents (IA) encoded by Kv4.2 and Kv4.3 pore-forming (α) subunits of the Kv4 subfamily are key regulators of neuronal excitability. Previous studies have suggested a role for Kv4.1 α-subunits in regulating the firing properties of mouse suprachiasmatic nucleus (SCN) neurons. To test this, we utilized an RNA-interference strategy to knockdown Kv4.1, acutely and selectively, in the SCN. Current-clamp recordings revealed that the in vivo knockdown of Kv4.1 significantly (p < 0...
May 2017: ENeuro
https://www.readbyqxmd.com/read/28553739/anatomical-and-behavioral-investigation-of-c1ql3-in-the-mouse-suprachiasmatic-nucleus
#13
Kylie S Chew, Diego C Fernandez, Samer Hattar, Thomas C Südhof, David C Martinelli
Many biochemical, physiological, and behavioral processes such as glucose metabolism, body temperature, and sleep-wake cycles show regular daily rhythms. These circadian rhythms are adjusted to the environmental light-dark cycle by a central pacemaker located in the suprachiasmatic nucleus (SCN) in order for the processes to occur at appropriate times of day. Here, we investigated the expression and function of a synaptic organizing protein, C1QL3, in the SCN. We found that C1ql3 is robustly expressed in the SCN...
June 2017: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/28553673/fractal-regulation-in-temporal-activity-fluctuations-a-biomarker-for-circadian-control-and-beyond
#14
Peng Li, Tommy To, Wei-Yin Chiang, Carolina Escobar, Ruud M Buijs, Kun Hu
Motor activity in humans and other animals possesses fractal temporal fluctuations that co-exists with circadian or daily activity rhythms. The perturbations in fractal activity patterns are often accompanied by altered circadian/daily rhythms. The goal of this study is to test whether fractal regulation in motor activity provides physiological information independent from 24-h/circadian rhythmicity. To achieve the goal, we studied locomotor activity recordings of rats with the lesion of the suprachiasmatic nucleus (SCN) that are known to have diminished circadian/daily activity rhythms and perturbed fractal regulation...
2017: JSM Biomark
https://www.readbyqxmd.com/read/28547658/time-of-day-dependent-expression-of-purinergic-receptors-in-mouse-suprachiasmatic-nucleus
#15
Julian Lommen, Anna Stahr, Marc Ingenwerth, Amira A H Ali, Charlotte von Gall
Purinergic P2X and P2Y receptors are involved in mediating intercellular signalling via purines such as adenosine triphosphate (ATP). P2X and P2Y receptors have been implicated in numerous body functions including learning, memory and sleep. All of these body functions show time-of-day-dependent variations controlled by the master circadian oscillator located in the suprachiasmatic nucleus (SCN). Evidence exists for a role of purinergic signalling in intercellular coupling within SCN. However, few studies have been performed on the expression of purinergic receptors in SCN...
May 26, 2017: Cell and Tissue Research
https://www.readbyqxmd.com/read/28546123/distribution-of-tyrosine-hydroxylase-immunoreactive-neurons-in-the-brain-of-the-viviparous-fish-gambusia-affinis
#16
Shilpa K Bhat, C B Ganesh
Tyrosine hydroxylase (TH) is the common precursor enzyme involved in the biosynthetic pathway of the catecholaminergic neurotransmitters, dopamine and norepinephrine. In this investigation, the neuroanatomical distribution of TH-immunoreactivity was studied in the brain of the female mosquitofish Gambusia affinis. Numerous intensely stained TH-immunoreactive (ir) neurons were scattered in the olfactory bulb with their fibres extending towards the medial olfactory tract, whereas few telencephalic TH-ir cells with distinct fibres were observed in the dorsal nucleus of area ventralis telencephali and the posterior nucleus of area ventralis telencephali regions...
May 22, 2017: Journal of Chemical Neuroanatomy
https://www.readbyqxmd.com/read/28535270/intrinsically-photosensitive-retinal-ganglion-cell-function-sleep-efficiency-and-depression-in-advanced-age-related-macular-degeneration
#17
Michelle L Maynard, Andrew J Zele, Anthony S Kwan, Beatrix Feigl
Purpose: Melanopsin expressing intrinsically photosensitive retinal ganglion cells (ipRGC) input to multiple brain regions including those for pupil control, circadian rhythms, sleep and mood regulation. Here we measured ipRGC function and its relationship to sleep quality and depression in patients with advanced AMD. Methods: The melanopsin-mediated post-illumination pupil response (PIPR) was measured in 53 patients with advanced AMD (age 78.8 ± 8.8 years) and in 20 healthy controls (age 72...
February 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28533170/synchronizing-effects-of-melatonin-on-diurnal-and-circadian-rhythms
#18
REVIEW
Martina Pfeffer, Horst-Werner Korf, Helmut Wicht
In mammals, the rhythmic secretion of melatonin from the pineal gland is driven by the circadian clock in the suprachiasmatic nucleus (SCN) of the hypothalamus. The robust nightly peak of melatonin secretion is an output signal of the circadian clock and is supposed to deliver the circadian message to the whole of the organism. Since the circadian system regulates many behavioral and physiological processes, its disruption by external (shift-work, jet-lag) or internal desynchronization (blindness, aging) causes many different health problems...
May 19, 2017: General and Comparative Endocrinology
https://www.readbyqxmd.com/read/28528901/responses-to-spatial-contrast-in-the-mouse-suprachiasmatic-nuclei
#19
Joshua W Mouland, Adam R Stinchcombe, Daniel B Forger, Timothy M Brown, Robert J Lucas
A direct retinal projection targets the suprachiasmatic nucleus (SCN) (an important hypothalamic control center). The accepted function of this projection is to convey information about ambient light (irradiance) to synchronize the SCN's endogenous circadian clock with local time and drive the diurnal variations in physiology and behavior [1-4]. Here, we report that it also renders the SCN responsive to visual images. We map spatial receptive fields (RFs) for SCN neurons and find that only a minority are excited (or inhibited) by light from across the scene as expected for irradiance detectors...
June 5, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28505726/entrainment-range-of-the-suprachiasmatic-nucleus-affected-by-the-difference-in-the-neuronal-amplitudes-between-the-light-sensitive-and-light-insensitive-regions
#20
Changgui Gu, Huijie Yang, Zhongyuan Ruan
Mammals not only can be synchronized to the natural 24-h light-dark cycle, but also to a cycle with a non-24-h period. The range of the period of the external cycle, for which the animals can be entrained to, is called the entrainment range, which differs among species. The entrainment range as a characteristic of the animal is determined by the main circadian clock, i.e., the suprachiasmatic nucleus (SCN) in the brain. The SCN is composed of ∼10000 heterogeneous neurons, which can be divided into two subgroups, i...
April 2017: Physical Review. E
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