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suprachiasmatic nucleus

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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
#1
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
#2
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
#3
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
#4
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...
December 29, 2016: 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
#5
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-lifespan-the-hypothalamic-deregulation-hypothesis
#6
Arvin M Gouw, Gizem Efe, Rita Barakat, Andrew Preecha, Movarid Mehdizadeh, Steven A Garan, George A Brooks
In several species caloric restriction (CR) extends lifespan. 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 lifespan 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)...
December 23, 2016: Physiological Genomics
https://www.readbyqxmd.com/read/28006027/evidence-for-weakened-intercellular-coupling-in-the-mammalian-circadian-clock-under-long-photoperiod
#7
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
https://www.readbyqxmd.com/read/28004075/regulation-of-reproduction-by-the-circadian-rhythms
#8
Wen-Xiang Zhang, Si-Yu Chen, Chang Liu
Mammals synchronize their circadian activity primarily to the cycles of light and darkness in the environment. Circadian rhythm is controlled by the central clock in the hypothalamic suprachiasmatic nucleus (SCN) and the peripheral clocks in various tissues. More importantly, the central clock can integrate photic/nonphotic signals to generate rhythmic outputs, and then drive the slave oscillators in peripheral tissues through neuroendocrine and behavioral signals. Human reproductive activities, as some other physiological functions, are controlled by the biological clocks...
December 25, 2016: Sheng Li Xue Bao: [Acta Physiologica Sinica]
https://www.readbyqxmd.com/read/28003802/restricted-feeding-schedules-modulate-in-a-different-manner-the-expression-of-clock-genes-in-rat-hypothalamic-nuclei
#9
Leonardo D De Araujo, Silvia L Roa, Ana C Bueno, Fernanda B Coeli-Lacchini, Clarissa S Martins, Ernane T Uchoa, Jose Antunes-Rodrigues, Lucila L Elias, Paula C Elias, Ayrton C Moreira, Margaret De Castro
Food access restriction is associated to changes in gene expression of the circadian clock system. However, there are only a few studies investigating the effects of non-photic synchronizers, such as food entrainment, on the expression of clock genes in the central oscillators. We hypothesized that different feeding restriction patterns could modulate the expression of clock genes in the suprachiasmatic nucleus (SCN) "master" clock and in extra-SCN oscillators such as the paraventricular (PVN) and arcuate (ARC) hypothalamic nuclei...
2016: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/27997334/ontogeny-of-clock-and-kiss-1-metastasis-suppressor-kiss1-gene-expression-in-the-prepubertal-mouse-hypothalamus
#10
Cassandra C Yap, Peter J Mark, Brendan J Waddell, Jeremy T Smith
Kisspeptin is crucial for the generation of the circadian-gated preovulatory gonadotrophin-releasing hormone (GnRH)-LH surge in female rodents, with expression in the anteroventral periventricular nucleus (AVPV) peaking in the late afternoon of pro-oestrus. Given kisspeptin expression is established before puberty, the aim of the present study was to investigate kisspeptin and clock gene rhythms during the neonatal period. Anterior and posterior hypothalami were collected from C57BL/6J mice on Postnatal Days (P) 5, 15 and 25, at six time points across 24h, for analysis of gene expression by reverse transcription-quantitative polymerase chain reaction...
December 21, 2016: Reproduction, Fertility, and Development
https://www.readbyqxmd.com/read/27997028/differential-sensitivity-to-ethanol-induced-circadian-rhythm-disruption-in-adolescent-and-adult-mice
#11
Christina L Ruby, Kaitlyn N Palmer, Jiawen Zhang, Megan O Risinger, Melissa A Butkowski, H Scott Swartzwelder
BACKGROUND: Growing evidence supports a central role for the circadian system in alcohol use disorders, but few studies have examined this relationship during adolescence. In mammals, circadian rhythms are regulated by the suprachiasmatic nucleus, a biological clock whose timing is synchronized (reset) to the environment primarily by light (photic) input. Alcohol (ethanol [EtOH]) disrupts circadian timing in part by attenuating photic phase-resetting responses in adult rodents. However, circadian rhythms change throughout life and it is not yet known whether EtOH has similar effects on circadian regulation during adolescence...
January 2017: Alcoholism, Clinical and Experimental Research
https://www.readbyqxmd.com/read/27992553/intrinsically-photosensitive-retinal-ganglion-cells-iprgcs-are-necessary-for-light-entrainment-of-peripheral-clocks
#12
Paulo Kofuji, Ludovic S Mure, Logan J Massman, Nicole Purrier, Satchidananda Panda, William C Engeland
Light is a powerful entrainer of circadian clocks in almost all eukaryotic organisms promoting synchronization of internal circadian rhythms with external environmental light-dark (LD) cycles. In mammals, the circadian system is organized in a hierarchical manner, in which a central pacemaker in the suprachiasmatic nucleus (SCN) synchronizes oscillators in peripheral tissues. Recent evidence demonstrates that photoentrainment of the SCN proceeds via signaling from a subpopulation of retinal ganglion cells (RGCs) which are melanopsin-expressing and intrinsically photosensitive (ipRGCs)...
2016: PloS One
https://www.readbyqxmd.com/read/27992087/urokinase-type-plasminogen-activator-modulates-mammalian-circadian-clock-phase-regulation-in-tissue-type-plasminogen-activator-knockout-mice
#13
Joanna M Cooper, Ashutosh Rastogi, Jessica A Krizo, Eric M Mintz, Rebecca A Prosser
Glutamate phase shifts the circadian clock in the mammalian suprachiasmatic nucleus (SCN) by activating NMDA receptors. Tissue-type plasminogen activator (tPA) gates phase shifts by activating plasmin to generate m(ature)BDNF, which binds TrkB receptors allowing clock phase shifts. Here we investigate phase shifting in tPA knockout (tPA(-/-) ; B6.129S2-Plat(tm1Mlg) /J) mice, and identify urokinase-type plasminogen activator (uPA) as an additional circadian clock regulator. Behavioral activity rhythms in tPA(-/-) mice entrain to a light-dark (LD) cycle and phase shift in response to nocturnal light pulses with no apparent loss in sensitivity...
December 19, 2016: European Journal of Neuroscience
https://www.readbyqxmd.com/read/27991900/molecular-interrogation-of-hypothalamic-organization-reveals-distinct-dopamine-neuronal-subtypes
#14
Roman A Romanov, Amit Zeisel, Joanne Bakker, Fatima Girach, Arash Hellysaz, Raju Tomer, Alán Alpár, Jan Mulder, Frédéric Clotman, Erik Keimpema, Brian Hsueh, Ailey K Crow, Henrik Martens, Christian Schwindling, Daniela Calvigioni, Jaideep S Bains, Zoltán Máté, Gábor Szabó, Yuchio Yanagawa, Ming-Dong Zhang, Andre Rendeiro, Matthias Farlik, Mathias Uhlén, Peer Wulff, Christoph Bock, Christian Broberger, Karl Deisseroth, Tomas Hökfelt, Sten Linnarsson, Tamas L Horvath, Tibor Harkany
The hypothalamus contains the highest diversity of neurons in the brain. Many of these neurons can co-release neurotransmitters and neuropeptides in a use-dependent manner. Investigators have hitherto relied on candidate protein-based tools to correlate behavioral, endocrine and gender traits with hypothalamic neuron identity. Here we map neuronal identities in the hypothalamus by single-cell RNA sequencing. We distinguished 62 neuronal subtypes producing glutamatergic, dopaminergic or GABAergic markers for synaptic neurotransmission and harboring the ability to engage in task-dependent neurotransmitter switching...
December 19, 2016: Nature Neuroscience
https://www.readbyqxmd.com/read/27920039/systems-chronobiology-global-analysis-of-gene-regulation-in-a-24-hour-periodic-world
#15
Jérôme Mermet, Jake Yeung, Felix Naef
Mammals have evolved an internal timing system, the circadian clock, which synchronizes physiology and behavior to the daily light and dark cycles of the Earth. The master clock, located in the suprachiasmatic nucleus (SCN) of the brain, takes fluctuating light input from the retina and synchronizes other tissues to the same internal rhythm. The molecular clocks that drive these circadian rhythms are ticking in nearly all cells in the body. Efforts in systems chronobiology are now being directed at understanding, on a comprehensive scale, how the circadian clock controls different layers of gene regulation to provide robust timing cues at the cellular and tissue level...
December 5, 2016: Cold Spring Harbor Perspectives in Biology
https://www.readbyqxmd.com/read/27916729/enkephalin-and-neuropeptide-y-interaction-in-the-intergeniculate-leaflet-network-a-part-of-the-mammalian-biological-clock
#16
K Palus, L Chrobok, M Kepczynski, M H Lewandowski
The intergeniculate leaflet (IGL) is a flat thalamic nucleus implicated in the modulation of circadian rhythmicity. In rat, two main GABAergic subpopulations can be distinguished in the IGL: neurons synthesizing neuropeptide Y (NPY), which directly innervates the suprachiasmatic nuclei, and enkephalinergic cells, which connect contralaterally located leaflets. The aim of this study was to evaluate possible effects of inner IGL neurotransmitters on the spontaneous and synaptic activity of IGL neurons. The data presented in this article provide evidence that enkephalin, and not NPY, could act upon the majority of IGL neurons...
December 2, 2016: Neuroscience
https://www.readbyqxmd.com/read/27906111/the-functional-significance-of-the-skeletal-muscle-clock-lessons-from-bmal1-knockout-models
#17
REVIEW
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...
October 13, 2016: Skeletal Muscle
https://www.readbyqxmd.com/read/27894927/the-dynamics-of-gaba-signaling-revelations-from-the-circadian-pacemaker-in-the-suprachiasmatic-nucleus
#18
REVIEW
H Elliott Albers, James C Walton, Karen L Gamble, John K McNeill, Daniel L Hummer
Virtually every neuron within the suprachiasmatic nucleus (SCN) communicates via GABAergic signaling. The extracellular levels of GABA within the SCN are determined by a complex interaction of synthesis and transport, as well as synaptic and non-synaptic release. The response to GABA is mediated by GABAA receptors that respond to both phasic and tonic GABA release and that can produce excitatory as well as inhibitory cellular responses. GABA also influences circadian control through the exclusively inhibitory effects of GABAB receptors...
January 2017: Frontiers in Neuroendocrinology
https://www.readbyqxmd.com/read/27869182/the-effects-of-non-self-sustained-oscillators-on-the-en-trainment-ability-of-the-suprachiasmatic-nucleus
#19
Changgui Gu, Ming Tang, Jos H T Rohling, Huijie Yang
In mammals, the circadian rhythms of behavioral and physiological activities are regulated by an endogenous clock located in the suprachiasmatic nucleus (SCN). The SCN is composed of ~20,000 neurons, of which some are capable of self-sustained oscillations, while the others do not oscillate in a self-sustainable manner, but show arrhythmic patterns or damped oscillations. Thus far, the effects of these non-self-sustained oscillatory neurons are not fully explored. Here, we examined how the proportion of the non-self-sustained oscillators affects the free running period under constant darkness and the ability to entrain to the light-dark cycle...
November 21, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27852737/role-of-fructose-and-fructokinase-in-acute-dehydration-induced-vasopressin-gene-expression-and-secretion-in-mice
#20
Zhilin Song, Carlos A Roncal-Jimenez, Miguel A Lanaspa-Garcia, Sarah A Oppelt, Masanari Kuwabara, Thomas Jensen, Tamara Milagres, Ana Andres-Hernando, Takuji Ishimoto, Gabriela E Garcia, Ginger C Johnson, Paul S MacLean, Laura-Gabriela Sanchez-Lozada, Dean R Tolan, Richard J Johnson
BACKGROUND: Fructose stimulates vasopressin in humans and can be generated endogenously by activation of the polyol pathway with hyperosmolarity. We hypothesized that fructose metabolism in the hypothalamus might partly control vasopressin responses after acute dehydration. METHODS: Wildtype and fructokinase-knockout mice were deprived of water for 24 hours. The supraoptic nucleus was evaluated for vasopressin and the aldose reductase-fructokinase pathway. The posterior pituitary vasopressin and serum copeptin levels were examined...
November 16, 2016: Journal of Neurophysiology
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