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suprachiasmatic nucleus

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https://www.readbyqxmd.com/read/29237755/differential-contribution-of-ca2-sources-to-day-and-night-bk-current-activation-in-the-circadian-clock
#1
Joshua P Whitt, Beth A McNally, Andrea L Meredith
Large conductance K+ (BK) channels are expressed widely in neurons, where their activation is regulated by membrane depolarization and intracellular Ca2+ (Ca2+i). To enable this regulation, BK channels functionally couple to both voltage-gated Ca2+ channels (VGCCs) and channels mediating Ca2+ release from intracellular stores. However, the relationship between BK channels and their specific Ca2+ source for particular patterns of excitability is not well understood. In neurons within the suprachiasmatic nucleus (SCN)-the brain's circadian clock-BK current, VGCC current, and Ca2+i are diurnally regulated, but paradoxically, BK current is greatest at night when VGCC current and Ca2+i are reduced...
December 13, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/29230807/a-comparative-study-of-the-neural-stem-cell-niche-in-the-adult-hypothalamus-of-human-mouse-rat-and-grey-mouse-lemur-microcebus-murinus
#2
Giuliana Pellegrino, Claire Trubert, Jérémy Terrien, Fabien Pifferi, Danièle Leroy, Anne Loyens, Martine Migaud, Marc Baroncini, Claude-Alain Maurage, Christian Fontaine, Vincent Prévot, Ariane Sharif
The adult brain contains niches of neural stem cells that continuously add new neurons to selected circuits throughout life. Two niches have been extensively studied in various mammalian species including humans, the subventricular zone of the lateral ventricles and the subgranular zone of the hippocampal dentate gyrus. Recently, studies conducted mainly in rodents have identified a third neurogenic niche in the adult hypothalamus. In order to evaluate whether a neural stem cell niche also exists in the adult hypothalamus in humans, we performed multiple immunofluorescence labeling to assess the expression of a panel of neural stem/progenitor cell (NPC) markers (Sox2, nestin, vimentin, GLAST, GFAP) in the human hypothalamus and compared them with the mouse, rat and a non-human primate species, the grey mouse lemur (Microcebus murinus)...
December 12, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/29230328/circadian-rhythm-disturbances-in-mood-disorders-insights-into-the-role-of-the-suprachiasmatic-nucleus
#3
REVIEW
Chelsea A Vadnie, Colleen A McClung
Circadian rhythm disturbances are a common symptom among individuals with mood disorders. The suprachiasmatic nucleus (SCN), in the ventral part of the anterior hypothalamus, orchestrates physiological and behavioral circadian rhythms. The SCN consists of self-sustaining oscillators and receives photic and nonphotic cues, which entrain the SCN to the external environment. In turn, through synaptic and hormonal mechanisms, the SCN can drive and synchronize circadian rhythms in extra-SCN brain regions and peripheral tissues...
2017: Neural Plasticity
https://www.readbyqxmd.com/read/29224669/circadian-aspects-of-adipokine-regulation-in-rodents
#4
REVIEW
Etienne Challet
Most hormones display daily fluctuations of secretion during the 24-h cycle. This is also the case for adipokines, in particular the anorexigenic hormone, leptin. The temporal organization of the endocrine system is principally controlled by a network of circadian clocks. The circadian network comprises a master circadian clock, located in the suprachiasmatic nucleus of the hypothalamus, synchronized to the ambient light, and secondary circadian clocks found in various peripheral organs, such as the adipose tissues...
December 2017: Best Practice & Research. Clinical Endocrinology & Metabolism
https://www.readbyqxmd.com/read/29224666/central-and-peripheral-roles-of-vasopressin-in-the-circadian-defense-of-body-hydration
#5
REVIEW
Claire Gizowski, Eric Trudel, Charles W Bourque
Vasopressin is a neuropeptide synthesized by specific subsets of neurons within the eye and brain. Studies in rats and mice have shown that vasopressin produced by magnocellular neurosecretory cells (MNCs) that project to the neurohypophysis is released into the blood circulation where it serves as an antidiuretic hormone to promote water reabsorption from the kidney. Moreover vasopressin is a neurotransmitter and neuromodulator that contributes to time-keeping within the master circadian clock (i.e. the suprachiasmatic nucleus, SCN) and is also used as an output signal by SCN neurons to direct centrally mediated circadian rhythms...
December 2017: Best Practice & Research. Clinical Endocrinology & Metabolism
https://www.readbyqxmd.com/read/29224246/circadian-peak-dopaminergic-activity-response-at-the-biological-clock-pacemaker-suprachiasmatic-nucleus-area-mediates-the-metabolic-responsiveness-to-a-high-fat-diet
#6
Shuqin Luo, Yahong Zhang, Michael Ezrokhi, Yang Li, Tsung-Huang Tsai, Anthony H Cincotta
Among vertebrate species of the major vertebrate classes in the wild, a seasonal rhythm of whole body fuel metabolism, oscillating from lean to obese condition, is a common biological phenomenon. This annual cycle is driven in part by annual changes in the circadian dopaminergic signaling at the suprachiasmatic nuclei (SCN), with diminution of circadian peak dopaminergic activity at the SCN facilitating development of the seasonal obese insulin resistant condition. The present study investigated whether such an ancient circadian dopamine-SCN activity system for expression of the seasonal obese, insulin resistant phenotype may be operative in animals made obese, insulin resistant by high fat feeding and if so whether reinstatement of the circadian dopaminergic peak at the SCN would be sufficient to reverse the adverse metabolic impact of the high fat diet without alteration of caloric intake...
December 10, 2017: Journal of Neuroendocrinology
https://www.readbyqxmd.com/read/29223281/human-studies-on-hypothalamo-pituitary-adrenal-hpa-axis
#7
REVIEW
Kamani Liyanarachchi, Richard Ross, Miguel Debono
The daily rhythm of the hypothalamo-pituitary-adrenal (HPA) axis is regulated by the central clock in the suprachiasmatic nucleus. Cortisol, a glucocorticoid, acts as a secondary messenger between the central clock and the peripheral tissues. Changes in clock time, as seen in shift workers, alters the HPA axis and results in metabolic disturbances associated with ill health. Depression, anorexia nervosa and obstructive sleep apnoea, are associated with cortisol rhythm phase shifts and increased cortisol exposure...
October 2017: Best Practice & Research. Clinical Endocrinology & Metabolism
https://www.readbyqxmd.com/read/29223143/neurobiological-functions-of-the-period-circadian-clock-2-gene-per2
#8
REVIEW
Mikyung Kim, June Bryan de la Peña, Jae Hoon Cheong, Hee Jin Kim
Most organisms have adapted to a circadian rhythm that follows a roughly 24-hour cycle, which is modulated by both internal (clock-related genes) and external (environment) factors. In such organisms, the central nervous system (CNS) is influenced by the circadian rhythm of individual cells. Furthermore, the period circadian clock 2 (Per2) gene is an important component of the circadian clock, which modulates the circadian rhythm. Per2 is mainly expressed in the suprachiasmatic nucleus (SCN) of the hypothalamus as well as other brain areas, including the midbrain and forebrain...
December 8, 2017: Biomolecules & Therapeutics
https://www.readbyqxmd.com/read/29219034/measuring-relative-coupling-strength-in-circadian-systems
#9
Christoph Schmal, Erik D Herzog, Hanspeter Herzel
Modern imaging techniques allow the monitoring of circadian rhythms of single cells. Coupling between these single cellular circadian oscillators can generate coherent periodic signals on the tissue level that subsequently orchestrate physiological outputs. The strength of coupling in such systems of oscillators is often unclear. In particular, effects on coupling strength by varying cell densities, by knockouts, and by inhibitor applications are debated. In this study, we suggest to quantify the relative coupling strength via analyzing period, phase, and amplitude distributions in ensembles of individual circadian oscillators...
December 1, 2017: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/29218725/characterization-of-retinal-ganglion-cell-horizontal-cell-and-amacrine-cell-types-expressing-the-neurotrophic-receptor-tyrosine-kinase-ret
#10
Nadia Parmhans, Szilard Sajgo, Jingwen Niu, Wenqin Luo, Tudor Constantin Badea
We report the retinal expression pattern of Ret, a receptor tyrosine kinase for the Glial Derived Neurotrophic Factor (GDNF) family ligands (GFLs), during development and in the adult mouse. Ret is initially expressed in Retinal Ganglion Cells (RGCs), followed by Horizontal Cells (HCs) and Amacrine Cells (ACs), beginning with the early stages of postmitotic development. Ret expression persists in all three classes of neurons in the adult. Using RNA sequencing, immunostaining and random sparse recombination, we show that Ret is expressed in at least three distinct types of ACs, and ten types of RGCs...
December 8, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/29215920/effects-of-genetic-variants-of-st8sia2-and-ncam1-genes-on-seasonal-mood-changes-and-circadian-preference-in-the-general-population
#11
So Yung Yang, Ji Hyun Baek, Youngah Cho, Eun-Young Cho, Yujin Choi, Yongkang Kim, Taesung Park, Kyung Sue Hong
ST8SIA2 and NCAM1 are functionally related genes forming polysialic acid (PSA) - neural cell adhesion molecule (NCAM) complex in suprachiasmatic nucleus (SCN), the regulating site of circadian biological rhythm. In this study, the relationship of ST8SIA2 and NCAM1 with circadian and seasonal rhythms of human behavior was explored. Subjects were 261 healthy Korean adults who were free of any history of clinically significant psychiatric symptoms. The phenotypes were circadian preference and seasonal change of mood and behavior (seasonality) measured by the Composite Scale of Morningness and the Seasonal Pattern Assessment Questionnaire, respectively...
December 7, 2017: Chronobiology International
https://www.readbyqxmd.com/read/29211510/forced-desynchronization-model-for-a-diurnal-primate
#12
Crhistiane A Silva, Laís I M Melo, Alina R Pires, Jordana C Barbalho, Andreia V Melo, Diego A C Fernandes, Everly B Oliveira, Carolina V M Azevedo, Trinitat Cambras, Antoni Díez-Noguera, John Fontenele-Araujo
The circadian system is organized in a hierarchy of multiple oscillators, with the suprachiasmatic nucleus (SCN) as the master oscillator in mammals. The SCN is formed by a group of coupled cell oscillators. Knowledge of this coupling mechanism is essential to understanding entrainment and the expression of circadian rhythms. Some authors suggest that light-dark (LD) cycles with periods near the limit of entrainment may be good models for promoting internal desynchronization, providing knowledge about the coupling mechanism...
December 6, 2017: Chronobiology International
https://www.readbyqxmd.com/read/29208411/distribution-of-nadph-diaphorase-reactivity-in-the-central-nervous-system-of-the-common-toad-bufo-bufo
#13
Claudia Pinelli, Arun G Jadhao, Anna Scandurra, Biagio D'Aniello
We examined the distribution of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d)-reactive elements in the central nervous system (CNS) of the common toad, Bufo bufo. The investigation involved adult male and female toads collected during the breeding season. Labeled neurons of different morphological appearances (weakly or darkly stained, unipolar, bipolar, and multipolar) and fibers were observed across all subdivisions of the amphibian brain. Overall, a similar distribution of NADPH-d-labeled neurons was observed in the brain of male and female toads...
December 2, 2017: Journal of Chemical Neuroanatomy
https://www.readbyqxmd.com/read/29202376/circadian-rhythm-in-idiopathic-normal-pressure-hydrocephalus
#14
Andreas Eleftheriou, Martin Ulander, Fredrik Lundin
OBJECTIVES: The pathogenesis of idiopathic normal pressure hydrocephalus (iNPH) takes place in structures close to the cerebral ventricular system. Suprachiasmatic nucleus (SCN), situated close to the third ventricle, is involved in circadian rhythm. Diurnal disturbances are well-known in demented patients. The cognitive decline in iNPH is potentially reversible after a shunt operation. Diurnal rhythm has never been studied in iNPH. We hypothesize that there is a disturbance of circadian rhythm in iNPH-patients and the aim was to study any changes of the diurnal rhythm (mesor and circadian period) as well as any changes of the diurnal amplitude and acrophase of the activity in iNPH-patients before and after a shunt operation...
November 29, 2017: Clinical Neurology and Neurosurgery
https://www.readbyqxmd.com/read/29198725/circadian-clock-mediated-regulation-of-blood-pressure
#15
REVIEW
Lauren G Douma, Michelle L Gumz
Most bodily functions vary over the course of a 24 hour day. Circadian rhythms in body temperature, sleep-wake cycles, metabolism, and blood pressure (BP) are just a few examples. These circadian rhythms are controlled by the central clock in the suprachiasmatic nucleus (SCN) of the hypothalamus and peripheral clocks located throughout the body. Light and food cues entrain these clocks to the time of day and this synchronicity contributes to the regulation of a variety of physiological processes with effects on overall health...
November 30, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/29182371/decrease-in-scale-invariance-of-activity-fluctuations-with-aging-and-in-patients-with-suprasellar-tumors
#16
S D Joustra, C Gu, J H T Rohling, L Pickering, M Klose, K Hu, F A Scheer, U Feldt-Rasmussen, P J Jennum, A M Pereira, N R Biermasz, J H Meijer
Motor activity in healthy young humans displays intrinsic fluctuations that are scale-invariant over a wide range of time scales (from minutes to hours). Human postmortem and animal lesion studies showed that the intact function of the suprachiasmatic nucleus (SCN) is required to maintain such scale-invariant patterns. We therefore hypothesized that scale invariance is degraded in patients treated for suprasellar tumors that compress the SCN. To test the hypothesis, we investigated 68 patients with nonfunctioning pituitary macroadenoma and 22 patients with craniopharyngioma, as well as 72 age-matched healthy controls (age range 21...
November 28, 2017: Chronobiology International
https://www.readbyqxmd.com/read/29172740/the-choroid-plexus-harbors-a-circadian-oscillator-modulated-by-estrogens
#17
Telma Quintela, Tânia Albuquerque, Gabriella Lundkvist, Andrea Carmine Belin, Daniela Talhada, Isabel Gonçalves, Eva Carro, Cecília R A Santos
The suprachiasmatic nucleus (SCN) of the hypothalamus is considered the master circadian oscillator in mammals. However, extra-SCN structures in the brain also display daily rhythms. Recently, we have demonstrated that the choroid plexus (CP) expresses core clock genes that are subjected to circadian regulation in a sex-dependent manner. By using CP explants cultured from female knock-in mice carrying the Period-luciferase transgene, we show that CP exhibits endogenous circadian rhythms of PERIOD2::LUCIFERASE expression...
November 27, 2017: Chronobiology International
https://www.readbyqxmd.com/read/29165002/adrenal-dependent-and-independent-stress-induced-per1-mrna-in-hypothalamic-paraventricular-nucleus-and-prefrontal-cortex-of-male-and-female-rats
#18
Lauren E Chun, Jenny Christensen, Elizabeth R Woodruff, Sarah J Morton, Laura R Hinds, Robert L Spencer
Oscillating clock gene expression gives rise to a molecular clock that is present not only in the body's master circadian pacemaker, the hypothalamic suprachiasmatic nucleus (SCN), but also in extra-SCN brain regions. These extra-SCN molecular clocks depend on the SCN for entrainment to a light:dark cycle. The SCN has limited neural efferents, so it may entrain extra-SCN molecular clocks through its well-established circadian control of glucocorticoid hormone secretion. Glucocorticoids can regulate the normal rhythmic expression of clock genes in some extra-SCN tissues...
November 22, 2017: Stress: the International Journal on the Biology of Stress
https://www.readbyqxmd.com/read/29161694/immunohistochemical-localization-of-darpp-32-in-the-brain-of-two-lungfishes-further-assessment-of-its-relationship-with-the-dopaminergic-system
#19
Jesús M López, Ruth Morona, Agustín González
The distribution of DARPP-32 (a phosphoprotein related to the dopamine D1 receptor) has been widely used as a means to clarify the brain regions with dopaminoceptive cells, primarily in representative species of tetrapods. The relationship between dopaminergic and dopaminoceptive elements is frequently analyzed using the catecholamine marker tyrosine hydroxylase (TH). In the present study, by means of combined immunohistochemistry, we have analyzed these relationships in lungfishes, the only group of sarcopterygian fishes represented by 6 extant species that are the phylogenetically closest living relatives of tetrapods...
November 22, 2017: Brain, Behavior and Evolution
https://www.readbyqxmd.com/read/29152136/postnatal-calpain-inhibition-elicits-cerebellar-cell-death-and-motor-dysfunction
#20
Junyao Li, Sanjuan Yang, Guoqi Zhu
Calpain-1 deletion elicits neurodevelopmental disorders, such as ataxia. However, the function of calpain in postnatal neurodevelopment and its mechanisms remain unknown. In this study, we revealed that postnatal intraperitoneal injection of various calpain inhibitors attenuated cerebellar cytosolic calpain activity. Moreover, postnatal application of calpeptin (2 mg/kg) apparently reduced spectrin breakdown, promoted suprachiasmatic nucleus circadian oscillatory protein (SCOP) accumulation in cerebellar tissue...
October 20, 2017: Oncotarget
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