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https://www.readbyqxmd.com/read/28994762/in-vitro-bioluminescence-assay-to-characterize-circadian-rhythm-in-mammary-epithelial-cells
#1
Mingzhu Fang, Hwan-Goo Kang, Youngil Park, Brian Estrella, Helmut Zarbl
The circadian rhythm is a fundamental physiological process present in all organisms that regulates biological processes ranging from gene expression to sleep behavior. In vertebrates, circadian rhythm is controlled by a molecular oscillator that functions in both the suprachiasmatic nucleus (SCN; central pacemaker) and individual cells comprising most peripheral tissues. More importantly, disruption of circadian rhythm by exposure to light-at-night, environmental stressors and/or toxicants is associated with increased risk of chronic diseases and aging...
September 28, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28974783/environmental-perturbation-of-the-circadian-clock-during-pregnancy-leads-to-transgenerational-mood-disorder-like-behaviors-in-mice
#2
Peng Zhang, Guang Li, Hui Li, XiaoQiu Tan, Hai-Ying Mary Cheng
It remains unknown whether chronic circadian disturbance (CCD) during pregnancy can lead to mood disorders in the offspring. Here we show that pregnant mice in the F0 generation that were exposed to CCD stress displayed depression-like behaviors, and produced offspring in the F1 and F2 generations that also exhibited mood-associated behavioral phenotypes despite the lack of direct stressful experiences during their postnatal or adult period. Prenatal CCD stress was correlated with the elevation of plasma corticosterone levels in F1 mice...
October 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28970786/circadian-clock-protein-content-and-daily-rhythm-of-locomotor-activity-are-altered-after-chronic-exposure-to-lead-in-rat
#3
Mariam Sabbar, Ouria Dkhissi-Benyahya, Abdelhamid Benazzouz, Nouria Lakhdar-Ghazal
Lead exposure has been reported to produce many clinical features, including parkinsonism. However, its consequences on the circadian rhythms are still unknown. Here we aimed to examine the circadian rhythms of locomotor activity following lead intoxication and investigate the mechanisms by which lead may induce alterations of circadian rhythms in rats. Male Wistar rats were injected with lead or sodium acetate (10 mg/kg/day, i.p.) during 4 weeks. Both groups were tested in the "open field" to quantify the exploratory activity and in the rotarod to evaluate motor coordination...
2017: Frontiers in Behavioral Neuroscience
https://www.readbyqxmd.com/read/28968417/effects-of-meal-composition-and-meal-timing-on-the-expression-of-genes-involved-in-hepatic-drug-metabolism-in-rats
#4
E M de Vries, J E Oosterman, H M Eggink, P de Goede, S Sen, E Foppen, O Boudzovitch-Surovtseva, A Boelen, J A Romijn, S E laFleur, A Kalsbeek
INTRODUCTION: With chronotherapy, drug administration is synchronized with daily rhythms in drug clearance and pharmacokinetics. Daily rhythms in gene expression are centrally mastered by the suprachiasmatic nucleus of the hypothalamus as well as by tissue clocks containing similar molecular mechanisms in peripheral organs. The central timing system is sensitive to changes in the external environment such as those of the light-dark cycle, meal timing and meal composition. We investigated how changes in diet composition and meal timing would affect the daily hepatic expression rhythms of the nuclear receptors PXR and CAR and of enzymes involved in P450 mediated drug metabolism, as such changes could have consequences for the practice of chronotherapy...
2017: PloS One
https://www.readbyqxmd.com/read/28964140/differences-in-intrinsic-amplitudes-of-neuronal-oscillators-improve-synchronization-in-the-suprachiasmatic-nucleus
#5
Changgui Gu, Huijie Yang
In mammals, a main clock located in the suprachiasmatic nucleus (SCN) regulates the ∼24 h rhythms of behavioral and physiological activities exposed to a natural 24 light-dark cycle or even under constant darkness. The rhythms originate from self-sustained oscillations of the SCN neurons, which differ in both intrinsic periods and intrinsic amplitudes. The intrinsic periods and the intrinsic amplitudes were found to be bound to specific regions in the previous experiments. In particular, neurons of smaller amplitudes and larger periods are located in a ventrolateral part, and neurons of larger amplitudes and smaller periods are in a dorsomedial part...
September 2017: Chaos
https://www.readbyqxmd.com/read/28956001/circadian-rhythm-of-intracellular-protein-synthesis-signaling-in-rat-cardiac-and-skeletal-muscles
#6
Shuo-Wen Chang, Toshinori Yoshihara, Shuichi Machida, Hisashi Naito
Intracellular signaling exhibits circadian variation in the suprachiasmatic nucleus and liver. However, it is unclear whether circadian regulation also extends to intracellular signaling pathways in the cardiac and skeletal muscles. Here, we examined circadian variation in the intracellular mammalian target of rapamycin (mTOR)/70 kDa ribosomal protein S6 kinase 1 (p70S6K) and extracellular signal-regulated kinase (ERK) pathways, which regulate protein synthesis in rat cardiac and skeletal muscles. Seven-week-old male Wistar rats were assigned to six groups: Zeitgeber time (ZT) 2, ZT6, ZT10, ZT14, ZT18, and ZT22 (ZT0, lights on; ZT12, lights off)...
March 2017: Biochemistry and Biophysics Reports
https://www.readbyqxmd.com/read/28954569/the-dorsal-medial-habenula-minimally-impacts-circadian-regulation-of-locomotor-activity-and-sleep
#7
Yun-Wei A Hsu, Jennifer J Gile, Jazmine G Perez, Glenn Morton, Miriam Ben-Hamo, Eric E Turner, Horacio O de la Iglesia
In nocturnal rodents, voluntary wheel-running activity (WRA) represents a self-reinforcing behavior. We have previously demonstrated that WRA is markedly reduced in mice with a region-specific deletion of the transcription factor Pou4f1 (Brn3a), which leads to an ablation of the dorsal medial habenula (dMHb). The decrease in WRA in these dMHb-lesioned (dMHb(CKO)) mice suggests that the dMHb constitutes a critical center for conveying reinforcement by exercise. However, WRA also represents a prominent output of the circadian system, and the possibility remains that the dMHb is a source of input to the master circadian pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus...
September 1, 2017: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/28946788/the-hepato-hypothalamic-pituitary-adrenal-renal-axis-mathematical-modeling-of-cortisol-s-production-metabolism-and-seasonal-variation
#8
Kamau Pierre, Naomi Schlesinger, Ioannis P Androulakis
Cortisol dynamics are governed by the integration of influences from the suprachiasmatic nucleus (SCN), the hypothalamic-pituitary-adrenal (HPA) axis, and metabolic enzymes, such as the 11β-hydroxysteroid dehydrogenase (HSD) family, which are highly expressed in hepatic and renal tissue. The coordinated regulation of cortisol dynamics is essential for the maintenance of a healthy state, and aberrant cortisol circadian rhythms are associated with various pathophysiological conditions. The duration of the light-dark cycle, or photoperiod, which regulates SCN activity, varies seasonally, and the shorter photoperiod winter season is associated with elevated cortisol levels, peak inflammatory disease incidence, and symptom exacerbation...
September 1, 2017: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/28943398/cold-sensing-trpm8-channel-participates-in-circadian-control-of-the-brown-adipose-tissue
#9
Maria Nathália Moraes, Leonardo Vinicius Monteiro de Assis, Felipe Dos Santos Henriques, Miguel Luiz Batista, Ali D Güler, Ana Maria de Lauro Castrucci
Transient receptor potential (TRP) channels are known to regulate energy metabolism, and TRPM8 has become an interesting player in this context. Here we demonstrate the role of the cold sensor TRPM8 in the regulation of clock gene and clock controlled genes in brown adipose tissue (BAT). We investigated TrpM8 temporal profile in the eyes, suprachiasmatic nucleus and BAT; only BAT showed temporal variation of TrpM8 transcripts. Eyes from mice lacking TRPM8 lost the temporal profile of Per1 in LD cycle. This alteration in the ocular circadian physiology may explain the delay in the onset of locomotor activity in response to light pulse, as compared to wild type animals (WT)...
September 21, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28943001/melatonin-modulates-monochromatic-light-induced-melatonin-receptor-expression-in-the-hypothalamus-of-chicks
#10
Liwei Zhang, Funing Chen, Jing Cao, Yulan Dong, Zixu Wang, Yaoxing Chen
To study the mechanism of the effect of monochromatic light on physiological function in chicken, a total of 192 newly hatched chicks were randomly divided into intact, sham-operated and pinealectomy groups then exposed to white light (WL), red light (RL), green light (GL) and blue light (BL) using a light-emitting diode (LED) system for two weeks. At P14, the hypothalami were immediately collected for immunohistochemical staining of melatonin receptor subtypes (Mel1a and Mel1b) and detection of Mel1a and Mel1b expressions using RT-PCR and western blot...
September 21, 2017: Acta Histochemica
https://www.readbyqxmd.com/read/28921823/encoding-seasonal-information-in-a-two-oscillator-model-of-the-multi-oscillator-circadian-clock
#11
Jihwan Myung, Scott D Pauls
The suprachiasmatic nucleus (SCN) is a collection of about 10,000 neurons, each of which functions as a circadian clock with slightly different periods and phases, that work in concert to form and maintain the master circadian clock for the organism. The diversity among neurons confers on the SCN the ability to robustly encode both the 24-hour light pattern as well as the seasonal time. Cluster synchronization brings the different neurons into line and reduces the large population to essentially two oscillators, coordinated by a macroscopic network motif of asymmetric repulsive-attractive coupling...
September 16, 2017: European Journal of Neuroscience
https://www.readbyqxmd.com/read/28912695/region-and-cell-specific-expression-of-transmembrane-collagens-in-mouse-brain
#12
Aboozar Monavarfeshani, Courtney N Knill, Ubadah Sabbagh, Jianmin Su, Michael A Fox
Unconventional collagens are nonfribrillar proteins that not only contribute to the structure of extracellular matrices but exhibit unique bio-activities. Although roles for unconventional collagens have been well-established in the development and function of non-neural tissues, only recently have studies identified roles for these proteins in brain development, and more specifically, in the formation and refinement of synaptic connections between neurons. Still, our understanding of the full cohort of unconventional collagens that are generated in the mammalian brain remains unclear...
2017: Frontiers in Integrative Neuroscience
https://www.readbyqxmd.com/read/28893605/oscillator-networks-with-tissue-specific-circadian-clocks-in-plants
#13
REVIEW
Keisuke Inoue, Takashi Araki, Motomu Endo
Many organisms rely on circadian clocks to synchronize their biological processes with the 24-hour rotation of the earth. In mammals, the circadian clock consists of a central clock in the suprachiasmatic nucleus and peripheral clocks in other tissues. The central clock is tightly coupled to synchronize rhythmicity and can organize peripheral clocks through neural and hormonal signals. In contrast to mammals, it has long been assumed that the circadian clocks in each plant cell is able to be entrained by external light, and they are only weakly coupled to each other...
September 8, 2017: Seminars in Cell & Developmental Biology
https://www.readbyqxmd.com/read/28860458/intracellular-chloride-regulation-in-avp-and-vip-neurons-of-the-suprachiasmatic-nucleus
#14
Nathan J Klett, Charles N Allen
Several reports have described excitatory GABA transmission in the suprachiasmatic nucleus (SCN), the master pacemaker of circadian physiology. However, there is disagreement regarding the prevalence, timing, and neuronal location of excitatory GABA transmission in the SCN. Whether GABA is inhibitory or excitatory depends, in part, on the intracellular concentration of chloride ([Cl(-)]i). Here, using ratiometric Cl(-) imaging, we have investigated intracellular chloride regulation in AVP and VIP-expressing SCN neurons and found evidence suggesting that [Cl(-)]i is higher during the day than during the night in both AVP+ and VIP+ neurons...
August 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28855650/novel-rbfox2-isoforms-associated-with-alternative-exon-usage-in-rat-cortex-and-suprachiasmatic-nucleus
#15
L M M Partridge, D A Carter
Transcriptome diversity in adult neurons is partly mediated by RNA binding proteins (RBPs), including the RBFOX factors. RBFOX3/NeuN, a neuronal maturity marker, is strangely depleted in suprachiasmatic nucleus (SCN) neurons, and may be compensated by a change in Rbfox2 expression. In this study, we found no superficial changes in Rbfox2 expression in the SCN, but mRNA population analysis revealed a distinct SCN transcript profile that includes multiple novel Rbfox2 isoforms. Of eleven isoforms in SCN and cerebral cortex that exhibit exon variation across two protein domains, we found a 3-fold higher abundance of a novel ('-12-40') C-terminal domain (CTD)-variant in the SCN...
August 30, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28855287/gaba-transporters-regulate-tonic-and-synaptic-gabaa-receptor-mediated-currents-in-the-suprachiasmatic-nucleus-neurons
#16
Michael G Moldavan, Olga Cravetchi, Charles N Allen
GABA is a principal neurotransmitter in the hypothalamic suprachiasmatic nucleus (SCN) that contributes to intercellular communication between individual circadian oscillators within the SCN network and the stability and precision of the circadian rhythms. GABA transporters (GAT) regulate the extracellular GABA concentration and modulate GABAA receptor (GABAAR)-mediated currents. GABA transport inhibitors were applied to study how GABAAR-mediated currents depend on the expression and function of GAT. Nipecotic acid inhibits GABA transport and induced an inward tonic current in concentration-dependent manner during whole-cell patch clamp recordings from SCN neurons...
August 30, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28851750/food-in-synchrony-with-melatonin-and-corticosterone-relieves-constant-light-disturbed-metabolism
#17
Adrián Báez-Ruiz, Natalí N Guerrero-Vargas, Fernando Cázarez-Márquez, Elizabeth Sabath, María Del Carmen Basualdo, Roberto Salgado-Delgado, Carolina Escobar, Ruud M Buijs
Circadian disruption is associated with metabolic disturbances such as hepatic steatosis (HS), obesity and type 2 diabetes. We hypothesized that HS, resulting from constant light (LL) exposure is due to an inconsistency between signals related to food intake and endocrine-driven suprachiasmatic nucleus (SCN) outputs. Indeed, exposing rats to LL induced locomotor, food intake and hormone arrhythmicity together with the development of HS. We investigated whether providing temporal signals such as 12-h food availability or driving a corticosterone plus melatonin rhythm could restore rhythmicity and prevent the metabolic disturbances under LL conditions in male rats...
December 2017: Journal of Endocrinology
https://www.readbyqxmd.com/read/28847141/na%C3%A2-%C2%BA-ca%C3%A2-%C3%A2-%C2%BA-exchanger-2-ncx2-in-the-circadian-clock-of-the-rat-suprachiasmatic-nucleus-colocalization-with-neuropeptides-and-daily-profiles-of-gene-expression-and-protein-levels
#18
Pi-Cheng Cheng, Ya-Shuan Chen, Rong-Chi Huang
The plasmalemmal Na⁺/Ca²⁺ changer (NCX) regulates intracellular Ca²⁺ by exchanging 3 Na⁺ for 1 Ca²⁺ in either the Ca²⁺ exit or Ca²⁺ entry mode. All three NCX isoforms NCX1, NCX2, and NCX3 are expressed in the rat brain, with isoform-specific differential distribution. In the central clock of suprachiasmatic nucleus (SCN), intracellular Ca²⁺ controls the circadian release of major neuropeptides, which are the arginine vasopressin (AVP), vasoactive intestinal peptide (VIP) and gastrin releasing peptide (GRP), and the NCX, most likely NCX1, rapidly clears depolarization-induced somatic Ca²⁺ influx...
August 31, 2017: Chinese Journal of Physiology
https://www.readbyqxmd.com/read/28844699/circadian-clocks-and-metabolism-implications-for-microbiome-and-aging
#19
REVIEW
Georgios K Paschos, Garret A FitzGerald
The circadian clock directs many aspects of metabolism, to separate in time opposing metabolic pathways and optimize metabolic efficiency. The master circadian clock of the suprachiasmatic nucleus synchronizes to light, while environmental cues such as temperature and feeding, out of phase with the light schedule, may synchronize peripheral clocks. This misalignment of central and peripheral clocks may be involved in the development of disease and the acceleration of aging, possibly in a gender-specific manner...
October 2017: Trends in Genetics: TIG
https://www.readbyqxmd.com/read/28828400/calcium-circadian-rhythmicity-in-the-suprachiasmatic-nucleus-cell-autonomy-and-network-modulation
#20
Takako Noguchi, Tanya L Leise, Nathaniel J Kingsbury, Tanja Diemer, Lexie L Wang, Michael A Henson, David K Welsh
Circadian rhythms of mammalian physiology and behavior are coordinated by the suprachiasmatic nucleus (SCN) in the hypothalamus. Within SCN neurons, various aspects of cell physiology exhibit circadian oscillations, including circadian clock gene expression, levels of intracellular Ca(2+) ([Ca(2+)]i), and neuronal firing rate. [Ca(2+)]i oscillates in SCN neurons even in the absence of neuronal firing. To determine the causal relationship between circadian clock gene expression and [Ca(2+)]i rhythms in the SCN, as well as the SCN neuronal network dependence of [Ca(2+)]i rhythms, we introduced GCaMP3, a genetically encoded fluorescent Ca(2+) indicator, into SCN neurons from PER2::LUC knock-in reporter mice...
July 2017: ENeuro
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