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suprachiasmatic nucleus

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https://www.readbyqxmd.com/read/28198033/synchrony-between-suprachiasmatic-nucleus-driven-signals-and-the-light-dark-cycle-is-essential-for-liver-homeostasis
#1
Ruud M Buijs, Natali Guerrero Vargas
No abstract text is available yet for this article.
February 15, 2017: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
https://www.readbyqxmd.com/read/28197551/ephrina5-signaling-is-required-for-the-distinctive-targeting-of-raphe-serotonin-neurons-in-the-forebrain
#2
Teng Teng, Afsaneh Gaillard, Aude Muzerelle, Patricia Gaspar
Serotonin (5-HT) neurotransmission in the brain relies on a widespread axon terminal network originating from the hindbrain raphe nuclei. These projections are topographically organized such that the dorsal (DR), and median raphe (MnR) nuclei have different brain targets. However, the guidance molecules involved in this selective targeting in development are unknown. Here, we show the implication of ephrinA5 signaling in this process. We find that the EphA5 gene is selectively expressed in a subset of 5-HT neurons during embryonic and postnatal development...
January 2017: ENeuro
https://www.readbyqxmd.com/read/28186121/astrocyte-deletion-of-bmal1-alters-daily-locomotor-activity-and-cognitive-functions-via-gaba-signalling
#3
Olga Barca-Mayo, Meritxell Pons-Espinal, Philipp Follert, Andrea Armirotti, Luca Berdondini, Davide De Pietri Tonelli
Circadian rhythms are controlled by a network of clock neurons in the central pacemaker, the suprachiasmatic nucleus (SCN). Core clock genes, such as Bmal1, are expressed in SCN neurons and in other brain cells, such as astrocytes. However, the role of astrocytic clock genes in controlling rhythmic behaviour is unknown. Here we show that ablation of Bmal1 in GLAST-positive astrocytes alters circadian locomotor behaviour and cognition in mice. Specifically, deletion of astrocytic Bmal1 has an impact on the neuronal clock through GABA signalling...
February 10, 2017: Nature Communications
https://www.readbyqxmd.com/read/28178768/distribution-of-endomorphin-like-immunoreactive-neurones-in-the-brain-of-the-cichlid-fish-oreochromis-mossambicus
#4
Vijayalaxmi, C B Ganesh
Endomorphins are tetrapeptides involved in pain and neuroendocrine responses with high affinity for mu opioid receptors in mammals. In the present investigation, we studied the distribution of endomorphin-like-immunoreactive (EM-L-ir) neurones in the brain of the cichlid fish Oreochromis mossambicus. Application of antisera against endomorphin 1 and 2 (EM-1-2) revealed the presence of EM-L-ir somata and fibres throughout the different subdivisions of the olfactory bulb such as the olfactory nerve layer and the granule cell layer...
February 8, 2017: Journal of Neuroendocrinology
https://www.readbyqxmd.com/read/28174180/suprachiasmatic-vasopressin-to-paraventricular-oxytocin-neurocircuit-in-the-hypothalamus-relays-light-reception-to-inhibition-of-feeding-behavior
#5
Putra Santoso, Masanori Nakata, Yoichi Ueta, Toshihiko Yada
Light syncronizes body's circadian rhythms by modulating the master clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus. In modern life, the extended and/or irregular light exposure impairs circadian rhythms and consequently promotes feeding and metabolic disorders. However, the neuronal pathway through which light is coupled to feeding behavior is less elucidated. The present study employed the light exposure during dark phase of the day in rats and observed its effect on neuronal activity and feeding behavior...
February 7, 2017: American Journal of Physiology. Endocrinology and Metabolism
https://www.readbyqxmd.com/read/28155916/dual-origins-of-the-intracellular-circadian-calcium-rhythm-in-the-suprachiasmatic-nucleus
#6
Ryosuke Enoki, Daisuke Ono, Shigeru Kuroda, Sato Honma, Ken-Ichi Honma
In mammals, the master circadian clock is located in the suprachiasmatic nucleus (SCN), where most neurons show circadian rhythms of intracellular Ca(2+) levels. However, the origin of these Ca(2+) rhythms remains largely unknown. In this study, we successfully monitored the intracellular circadian Ca(2+) rhythms together with the circadian PER2 and firing rhythms in a single SCN slice ex vivo, which enabled us to explore the origins. The phase relation between the circadian PER2 and Ca(2+) rhythms, but not between the circadian PER2 and firing rhythms, was significantly altered in Cry1/Cry2 double knockout mice, which display a loss of intercellular synchronization in the SCN...
February 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28150809/selective-binocular-vision-loss-in-two-subterranean-caviomorph-rodents-spalacopus-cyanus-and-ctenomys-talarum
#7
T Vega-Zuniga, F S Medina, G Marín, J C Letelier, A G Palacios, P Němec, C E Schleich, J Mpodozis
To what extent can the mammalian visual system be shaped by visual behavior? Here we analyze the shape of the visual fields, the densities and distribution of cells in the retinal ganglion-cell layer and the organization of the visual projections in two species of facultative non-strictly subterranean rodents, Spalacopus cyanus and Ctenomys talarum, aiming to compare these traits with those of phylogenetically closely related species possessing contrasting diurnal/nocturnal visual habits. S. cyanus shows a definite zone of frontal binocular overlap and a corresponding area centralis, but a highly reduced amount of ipsilateral retinal projections...
February 2, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28123663/a-hypothetic-aging-pathway-from-skin-to-hypothalamic-suprachiasmatic-nucleus-via-slow-wave-sleep
#8
Zi-Jian Cai
Many observations have demonstrated that the hypothalamic neuroendocrine change determines the chronological sequence of aging in mammals. However, it remains uncertain on the mechanism to account for the hypothalamic aging manifestations. In this article, it is pointed out that, as constantly exposed to sunshine and oxygen, the skin would undergo both telomere-shortening and oxidative senescent processes. The senescent alterations of skin, such as attenuation in electrodermal activities, would in turn reduce the emotional responses and memories...
July 2016: Sleep Science
https://www.readbyqxmd.com/read/28116759/improvement-of-a-patient-s-circadian-rhythm-sleep-disorders-by-aripiprazole-was-associated-with-stabilization-of-his-bipolar-illness
#9
Tetsuo Tashiro
Splitting of the behavioural activity phase has been found in nocturnal rodents with suprachiasmatic nucleus (SCN) coupling disorder. A similar phenomenon was observed in the sleep phase in the diurnal human discussed here, suggesting that there are so-called evening and morning oscillators in the SCN of humans. The present case suffered from bipolar disorder refractory to various treatments, and various circadian rhythm sleep disorders, such as delayed sleep phase, polyphasic sleep, separation of the sleep bout resembling splitting and circabidian rhythm (48 h), were found during prolonged depressive episodes with hypersomnia...
January 24, 2017: Journal of Sleep Research
https://www.readbyqxmd.com/read/28114877/modulation-of-circadian-clocks-by-nutrients-and-food-factors
#10
Hideaki Oike
Daily activity rhythms that are dominated by internal clocks are called circadian rhythms. A central clock is located in the suprachiasmatic nucleus of the hypothalamus, and peripheral clocks are located in most mammalian peripheral cells. The central clock is entrained by light/dark cycles, whereas peripheral clocks are entrained by feeding cycles. The effects of nutrients on the central and peripheral clocks have been investigated during the past decade and much interaction between them has come to light...
January 24, 2017: Bioscience, Biotechnology, and Biochemistry
https://www.readbyqxmd.com/read/28109907/circadian-gene-variants-and-breast-cancer
#11
Edyta Reszka, Monika Przybek, Olav Muurlink, Beata Pepłonska
The endogenous and self-sustained circadian rhythm generated and maintained in suprachiasmatic nucleus and peripheral tissues can coordinate various molecular, biochemical and physiological processes in living organisms resulting in the adaptation to environmental cues, e.g. light. Multifactorial breast cancer etiology also involves circadian gene alterations, especially among individuals exposed to light at night. Indeed, shift work that causes circadian disruption has been classified by the International Agency for Research on Cancer as a probable human carcinogen, group 2A...
April 1, 2017: Cancer Letters
https://www.readbyqxmd.com/read/28108951/physiological-links-of-circadian-clock-and-biological-clock-of-aging
#12
REVIEW
Fang Liu, Hung-Chun Chang
Circadian rhythms orchestrate biochemical and physiological processes in living organisms to respond the day/night cycle. In mammals, nearly all cells hold self-sustained circadian clocks meanwhile couple the intrinsic rhythms to systemic changes in a hierarchical manner. The suprachiasmatic nucleus (SCN) of the hypothalamus functions as the master pacemaker to initiate daily synchronization according to the photoperiod, in turn determines the phase of peripheral cellular clocks through a variety of signaling relays, including endocrine rhythms and metabolic cycles...
January 20, 2017: Protein & Cell
https://www.readbyqxmd.com/read/28090585/circadian-forced-desynchrony-of-the-master-clock-leads-to-phenotypic-manifestation-of-depression-in-rats
#13
Miriam Ben-Hamo, Tracy A Larson, Leanne S Duge, Carl Sikkema, Charles W Wilkinson, Horacio O de la Iglesia, Mónica M C González
In mammals, a master circadian clock within the suprachiasmatic nucleus (SCN) of the hypothalamus maintains the phase coherence among a wide array of behavioral and physiological circadian rhythms. Affective disorders are typically associated with disruption of this fine-tuned "internal synchronization," but whether this internal misalignment is part of the physiopathology of mood disorders is not clear. To date, depressive-like behavior in animal models has been induced by methods that fail to specifically target the SCN regulation of internal synchronization as the mode to generate depression...
November 2016: ENeuro
https://www.readbyqxmd.com/read/28057567/prenatal-administration-of-letrozole-reduces-sdn-and-scn-volume-and-cell-number-independent-of-partner-preference-in-the-male-rat
#14
Sandra Olvera-Hernández, Miguel Tapia-Rodríguez, Dick F Swaab, Alonso Fernández-Guasti
During development, the exposure to testosterone, and its conversion to estradiol by an enzyme complex termed aromatase, appears to be essential in adult male rats for the expression of typical male sexual behavior and female-sex preference. Some hypothalamic areas are the supposed neural bases of sexual preference/orientation; for example, male-oriented rams have a reduced volume of the sexually dimorphic nucleus (oSDN), while in homosexual men this nucleus does not differ from that of heterosexual men. In contrast, homosexual men showed a larger number of vasopressinergic cells in the suprachiasmatic nucleus (SCN)...
January 3, 2017: Physiology & Behavior
https://www.readbyqxmd.com/read/28052921/the-circadian-oscillator-of-the-cerebral-cortex-molecular-biochemical-and-behavioral-effects-of-deleting-the-arntl-clock-gene-in-cortical-neurons
#15
Tenna Bering, Mikkel Bloss Carstensen, Gitta Wörtwein, Pia Weikop, Martin Fredensborg Rath
A molecular circadian oscillator resides in neurons of the cerebral cortex, but its role is unknown. Using the Cre-LoxP method, we have here abolished the core clock gene Arntl in those neurons. This mouse represents the first model carrying a deletion of a circadian clock component specifically in an extrahypothalamic cell type of the brain. Molecular analyses of clock gene expression in the cerebral cortex of the Arntl conditional knockout mouse revealed disrupted circadian expression profiles, whereas clock gene expression in the suprachiasmatic nucleus was still rhythmic, thus showing that Arntl is required for normal function of the cortical circadian oscillator...
January 3, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28049647/regulating-the-suprachiasmatic-nucleus-scn-circadian-clockwork-interplay-between-cell-autonomous-and-circuit-level-mechanisms
#16
REVIEW
Erik D Herzog, Tracey Hermanstyne, Nicola J Smyllie, Michael H Hastings
The suprachiasmatic nucleus (SCN) is the principal circadian clock of the brain, directing daily cycles of behavior and physiology. SCN neurons contain a cell-autonomous transcription-based clockwork but, in turn, circuit-level interactions synchronize the 20,000 or so SCN neurons into a robust and coherent daily timer. Synchronization requires neuropeptide signaling, regulated by a reciprocal interdependence between the molecular clockwork and rhythmic electrical activity, which in turn depends on a daytime Na(+) drive and nighttime K(+) drag...
January 3, 2017: Cold Spring Harbor Perspectives in Biology
https://www.readbyqxmd.com/read/28042033/feeding-cycle-dependent-circulating-insulin-fluctuation-is-not-a-dominant-zeitgeber-for-mouse-peripheral-clocks-except-in-the-liver-differences-between-endogenous-and-exogenous-insulin-effects
#17
Katsutaka Oishi, Yuki Yasumoto, Sayaka Higo-Yamamoto, Saori Yamamoto, Naoki Ohkura
The master clock in the suprachiasmatic nucleus synchronizes peripheral clocks via humoral and neural signals in mammals. Insulin is thought to be a critical Zeitgeber (synchronizer) for peripheral clocks because it induces transient clock gene expression in cultured cells. However, the extent to which fluctuations in feeding-dependent endogenous insulin affect the temporal expression of clock genes remains unclear. We therefore investigated the temporal expression profiles of clock genes in the peripheral tissues of mice fed for 8 h during either the daytime (DF) or the nighttime (NF) for one week to determine the involvement of feeding cycle-dependent endogenous insulin rhythms in the circadian regulation of peripheral clocks...
January 29, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28017605/an-lhx1-regulated-transcriptional-network-controls-sleep-wake-coupling-and-thermal-resistance-of-the-central-circadian-clockworks
#18
Joseph L Bedont, Tara A LeGates, Ethan Buhr, Abhijith Bathini, Jonathan P Ling, Benjamin Bell, Mark N Wu, Philip C Wong, Russell N Van Gelder, Valerie Mongrain, Samer Hattar, Seth Blackshaw
The suprachiasmatic nucleus (SCN) is the central circadian clock in mammals. It is entrained by light but resistant to temperature shifts that entrain peripheral clocks [1-5]. The SCN expresses many functionally important neuropeptides, including vasoactive intestinal peptide (VIP), which drives light entrainment, synchrony, and amplitude of SCN cellular clocks and organizes circadian behavior [5-16]. The transcription factor LHX1 drives SCN Vip expression, and cellular desynchrony in Lhx1-deficient SCN largely results from Vip loss [17, 18]...
January 9, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28011880/roles-of-estrogen-receptor-alpha-in-mediating-life-span-the-hypothalamic-deregulation-hypothesis
#19
REVIEW
Arvin M Gouw, Gizem Efe, Rita Barakat, Andrew Preecha, Morvarid Mehdizadeh, Steven A Garan, George A Brooks
In several species caloric restriction (CR) extends life span. In this paper we integrate data from studies on CR and other sources to articulate the hypothalamic deregulation hypothesis by which estrogen receptor-alpha (ER-α) signaling in the hypothalamus and limbic system affects life span under the stress of CR in mammals. ER-α is one of two principal estrogen-binding receptors differentially expressed in the amygdala, hippocampus, and several key hypothalamic nuclei: the arcuate nucleus (ARN), preoptic area (POA), ventromedial nucleus (VMN), antero ventral periventricular nucleus (AVPV), paraventricular nucleus (PVN), supraoptic nucleus (SON), and suprachiasmatic nucleus (SCN)...
February 1, 2017: Physiological Genomics
https://www.readbyqxmd.com/read/28006027/evidence-for-weakened-intercellular-coupling-in-the-mammalian-circadian-clock-under-long-photoperiod
#20
M Renate Buijink, Assaf Almog, Charlotte B Wit, Ori Roethler, Anneke H O Olde Engberink, Johanna H Meijer, Diego Garlaschelli, Jos H T Rohling, Stephan Michel
For animals living in temperate latitudes, seasonal changes in day length are an important cue for adaptations of their physiology and behavior to the altered environmental conditions. The suprachiasmatic nucleus (SCN) is known as the central circadian clock in mammals, but may also play an important role in adaptations to different photoperiods. The SCN receives direct light input from the retina and is able to encode day-length by approximating the waveform of the electrical activity rhythm to the duration of daylight...
2016: PloS One
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