1
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Bonilla P, Shanks A, Nerella Y, Porcu A. Effects of chronic light cycle disruption during adolescence on circadian clock, neuronal activity rhythms, and behavior in mice. Front Neurosci 2024; 18:1418694. [PMID: 38952923 PMCID: PMC11215055 DOI: 10.3389/fnins.2024.1418694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Accepted: 05/29/2024] [Indexed: 07/03/2024] Open
Abstract
The advent of artificial lighting, particularly during the evening and night, has significantly altered the predictable daily light and dark cycles in recent times. Altered light environments disrupt the biological clock and negatively impact mood and cognition. Although adolescents commonly experience chronic changes in light/dark cycles, our understanding of how the adolescents' brain adapts to altered light environments remains limited. Here, we investigated the impact of chronic light cycle disruption (LCD) during adolescence, exposing adolescent mice to 19 h of light and 5 h of darkness for 5 days and 12 L:12D for 2 days per week (LCD group) for 4 weeks. We showed that LCD exposure did not affect circadian locomotor activity but impaired memory and increased avoidance response in adolescent mice. Clock gene expression and neuronal activity rhythms analysis revealed that LCD disrupted local molecular clock and neuronal activity in the dentate gyrus (DG) and in the medial amygdala (MeA) but not in the circadian pacemaker (SCN). In addition, we characterized the photoresponsiveness of the MeA and showed that somatostatin neurons are affected by acute and chronic aberrant light exposure during adolescence. Our research provides new evidence highlighting the potential consequences of altered light environments during pubertal development on neuronal physiology and behaviors.
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Affiliation(s)
| | | | | | - Alessandra Porcu
- Department of Drug Discovery and Biomedical Science, University of South Carolina, Columbia, SC, United States
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2
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Kitajima T. Commentary: Aripiprazole disrupts cellular synchrony in the suprachiasmatic nucleus and enhances entrainment to environmental light-dark cycles in mice. Front Neurosci 2024; 18:1371195. [PMID: 38707592 PMCID: PMC11066157 DOI: 10.3389/fnins.2024.1371195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 04/08/2024] [Indexed: 05/07/2024] Open
Affiliation(s)
- Tsuyoshi Kitajima
- Department of Psychiatry, Fujita Health University School of Medicine, Toyoake, Japan
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3
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Richardson MES, Browne CA, Mazariegos CIH. Reversible suppression of circadian-driven locomotor rhythms in mice using a gradual fragmentation of the day-night cycle. Sci Rep 2023; 13:14423. [PMID: 37660212 PMCID: PMC10475134 DOI: 10.1038/s41598-023-41029-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 08/21/2023] [Indexed: 09/04/2023] Open
Abstract
Circadian rhythms are regulated by molecular clockwork and drive 24-h behaviors such as locomotor activity, which can be rendered non-functional through genetic knockouts of clock genes. Circadian rhythms are robust in constant darkness (DD) but are modulated to become exactly 24 h by the external day-night cycle. Whether ill-timed light and dark exposure can render circadian behaviors non-functional to the extent of genetic knockouts is less clear. In this study, we discovered an environmental approach that led to a reduction or lack in rhythmic 24-h-circadian wheel-running locomotor behavior in mice (referred to as arrhythmicity). We first observed behavioral circadian arrhythmicity when mice were gradually exposed to a previously published disruptive environment called the fragmented day-night cycle (FDN-G), while maintaining activity alignment with the four dispersed fragments of darkness. Remarkably, upon exposure to constant darkness (DD) or constant light (LL), FDN-G mice lost any resemblance to the FDN-G-only phenotype and instead, exhibited sporadic activity bursts. Circadian rhythms are maintained in control mice with sudden FDN exposure (FDN-S) and fully restored in FDN-G mice either spontaneously in DD or after 12 h:12 h light-dark exposure. This is the first study to generate a light-dark environment that induces reversible suppression of circadian locomotor rhythms in mice.
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Affiliation(s)
- Melissa E S Richardson
- Department of Biological Sciences, Oakwood University, 7000 Adventist Blvd., Huntsville, AL, 35896, USA.
| | - Chérie-Akilah Browne
- Department of Biological Sciences, Oakwood University, 7000 Adventist Blvd., Huntsville, AL, 35896, USA
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4
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Ocampo-Espindola JL, Nikhil KL, Li JS, Herzog ED, Kiss IZ. Synchronization, clustering, and weak chimeras in a densely coupled transcription-based oscillator model for split circadian rhythms. CHAOS (WOODBURY, N.Y.) 2023; 33:083105. [PMID: 37535024 PMCID: PMC10403273 DOI: 10.1063/5.0156135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 07/08/2023] [Indexed: 08/04/2023]
Abstract
The synchronization dynamics for the circadian gene expression in the suprachiasmatic nucleus is investigated using a transcriptional circadian clock gene oscillator model. With global coupling in constant dark (DD) conditions, the model exhibits a one-cluster phase synchronized state, in dim light (dim LL), bistability between one- and two-cluster states and in bright LL, a two-cluster state. The two-cluster phase synchronized state, where some oscillator pairs synchronize in-phase, and some anti-phase, can explain the splitting of the circadian clock, i.e., generation of two bouts of daily activities with certain species, e.g., with hamsters. The one- and two-cluster states can be reached by transferring the animal from DD or bright LL to dim LL, i.e., the circadian synchrony has a memory effect. The stability of the one- and two-cluster states was interpreted analytically by extracting phase models from the ordinary differential equation models. In a modular network with two strongly coupled oscillator populations with weak intragroup coupling, with appropriate initial conditions, one group is synchronized to the one-cluster state and the other group to the two-cluster state, resulting in a weak-chimera state. Computational modeling suggests that the daily rhythms in sleep-wake depend on light intensity acting on bilateral networks of suprachiasmatic nucleus (SCN) oscillators. Addition of a network heterogeneity (coupling between the left and right SCN) allowed the system to exhibit chimera states. The simulations can guide experiments in the circadian rhythm research to explore the effect of light intensity on the complexities of circadian desynchronization.
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Affiliation(s)
| | - K. L. Nikhil
- Department of Biology, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130-4899, USA
| | - Jr-Shin Li
- Department of Electrical and Systems Engineering, Washington University in St Louis, 1 Brookings Drive, St. Louis, Missouri 63130, USA
| | - Erik D. Herzog
- Department of Biology, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130-4899, USA
| | - István Z. Kiss
- Department of Chemistry, Saint Louis University, 3501 Laclede Ave., St. Louis, Missouri 63103, USA
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5
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Vadnie CA, Petersen KA, Eberhardt LA, Hildebrand MA, Cerwensky AJ, Zhang H, Burns JN, Becker-Krail DD, DePoy LM, Logan RW, McClung CA. The Suprachiasmatic Nucleus Regulates Anxiety-Like Behavior in Mice. Front Neurosci 2022; 15:765850. [PMID: 35126036 PMCID: PMC8811036 DOI: 10.3389/fnins.2021.765850] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 12/23/2021] [Indexed: 01/21/2023] Open
Abstract
Individuals suffering from mood and anxiety disorders often show significant disturbances in sleep and circadian rhythms. Animal studies indicate that circadian rhythm disruption can cause increased depressive- and anxiety-like behavior, but the underlying mechanisms are unclear. One potential mechanism to explain how circadian rhythms are contributing to mood and anxiety disorders is through dysregulation of the suprachiasmatic nucleus (SCN) of the hypothalamus, known as the "central pacemaker." To investigate the role of the SCN in regulating depressive- and anxiety-like behavior in mice, we chronically manipulated the neural activity of the SCN using two optogenetic stimulation paradigms. As expected, chronic stimulation of the SCN late in the active phase (circadian time 21, CT21) resulted in a shortened period and dampened amplitude of homecage activity rhythms. We also repeatedly stimulated the SCN at unpredictable times during the active phase of mice when SCN firing rates are normally low. This resulted in dampened, fragmented, and unstable homecage activity rhythms. In both chronic SCN optogenetic stimulation paradigms, dampened homecage activity rhythms (decreased amplitude) were directly correlated with increased measures of anxiety-like behavior. In contrast, we only observed a correlation between behavioral despair and homecage activity amplitude in mice stimulated at CT21. Surprisingly, the change in period of homecage activity rhythms was not directly associated with anxiety- or depressive-like behavior. Finally, to determine if anxiety-like behavior is affected during a single SCN stimulation session, we acutely stimulated the SCN in the active phase (zeitgeber time 14-16, ZT14-16) during behavioral testing. Unexpectedly this also resulted in increased anxiety-like behavior. Taken together, these results indicate that SCN-mediated dampening of rhythms is directly correlated with increased anxiety-like behavior. This work is an important step in understanding how specific SCN neural activity disruptions affect depressive- and anxiety-related behavior.
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Affiliation(s)
- Chelsea A. Vadnie
- Department of Psychology, Ohio Wesleyan University, Delaware, OH, United States
| | - Kaitlyn A. Petersen
- Translational Neuroscience Program, Department of Psychiatry, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States
| | - Lauren A. Eberhardt
- Translational Neuroscience Program, Department of Psychiatry, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States
| | - Mariah A. Hildebrand
- Translational Neuroscience Program, Department of Psychiatry, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States
| | - Allison J. Cerwensky
- Translational Neuroscience Program, Department of Psychiatry, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States
| | - Hui Zhang
- Translational Neuroscience Program, Department of Psychiatry, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States
| | - Jennifer N. Burns
- Translational Neuroscience Program, Department of Psychiatry, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States
| | - Darius D. Becker-Krail
- Translational Neuroscience Program, Department of Psychiatry, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States
| | - Lauren M. DePoy
- Translational Neuroscience Program, Department of Psychiatry, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States
| | - Ryan W. Logan
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, United States
| | - Colleen A. McClung
- Translational Neuroscience Program, Department of Psychiatry, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States
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6
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Smith CB, van der Vinne V, McCartney E, Stowie AC, Leise TL, Martin-Burgos B, Molyneux PC, Garbutt LA, Brodsky MH, Davidson AJ, Harrington ME, Dallmann R, Weaver DR. Cell-Type-Specific Circadian Bioluminescence Rhythms in Dbp Reporter Mice. J Biol Rhythms 2022; 37:53-77. [PMID: 35023384 DOI: 10.1177/07487304211069452] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Circadian rhythms are endogenously generated physiological and molecular rhythms with a cycle length of about 24 h. Bioluminescent reporters have been exceptionally useful for studying circadian rhythms in numerous species. Here, we report development of a reporter mouse generated by modification of a widely expressed and highly rhythmic gene encoding D-site albumin promoter binding protein (Dbp). In this line of mice, firefly luciferase is expressed from the Dbp locus in a Cre recombinase-dependent manner, allowing assessment of bioluminescence rhythms in specific cellular populations. A mouse line in which luciferase expression was Cre-independent was also generated. The Dbp reporter alleles do not alter Dbp gene expression rhythms in liver or circadian locomotor activity rhythms. In vivo and ex vivo studies show the utility of the reporter alleles for monitoring rhythmicity. Our studies reveal cell-type-specific characteristics of rhythms among neuronal populations within the suprachiasmatic nuclei ex vivo. In vivo studies show Dbp-driven bioluminescence rhythms in the liver of Albumin-Cre;DbpKI/+ "liver reporter" mice. After a shift of the lighting schedule, locomotor activity achieved the proper phase relationship with the new lighting cycle more rapidly than hepatic bioluminescence did. As previously shown, restricting food access to the daytime altered the phase of hepatic rhythmicity. Our model allowed assessment of the rate of recovery from misalignment once animals were provided with food ad libitum. These studies confirm the previously demonstrated circadian misalignment following environmental perturbations and reveal the utility of this model for minimally invasive, longitudinal monitoring of rhythmicity from specific mouse tissues.
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Affiliation(s)
- Ciearra B Smith
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts.,Graduate Program in Neuroscience, University of Massachusetts Chan Medical School, Worcester, Massachusetts
| | - Vincent van der Vinne
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts.,Department of Biology, Williams College, Williamstown, Massachusetts
| | | | - Adam C Stowie
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia
| | - Tanya L Leise
- Department of Mathematics & Statistics, Amherst College, Amherst, Massachusetts
| | | | | | - Lauren A Garbutt
- Division of Biomedical Sciences, Warwick Medical School, The University of Warwick, Coventry, UK
| | - Michael H Brodsky
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts
| | - Alec J Davidson
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia
| | | | - Robert Dallmann
- Division of Biomedical Sciences, Warwick Medical School, The University of Warwick, Coventry, UK
| | - David R Weaver
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts.,Graduate Program in Neuroscience, University of Massachusetts Chan Medical School, Worcester, Massachusetts.,NeuroNexus Institute, University of Massachusetts Chan Medical School, Worcester, Massachusetts
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7
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Martin-Burgos B, Wang W, William I, Tir S, Mohammad I, Javed R, Smith S, Cui Y, Arzavala J, Mora D, Smith CB, van der Vinne V, Molyneux PC, Miller SC, Weaver DR, Leise TL, Harrington ME. Methods for Detecting PER2:LUCIFERASE Bioluminescence Rhythms in Freely Moving Mice. J Biol Rhythms 2021; 37:78-93. [PMID: 34873943 DOI: 10.1177/07487304211062829] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Circadian rhythms are driven by daily oscillations of gene expression. An important tool for studying cellular and tissue circadian rhythms is the use of a gene reporter, such as bioluminescence from the reporter gene luciferase controlled by a rhythmically expressed gene of interest. Here we describe methods that allow measurement of circadian bioluminescence from a freely moving mouse housed in a standard cage. Using a LumiCycle In Vivo (Actimetrics), we determined conditions that allow detection of circadian rhythms of bioluminescence from the PER2 reporter, PER2::LUC, in freely behaving mice. The LumiCycle In Vivo applies a background subtraction that corrects for effects of room temperature on photomultiplier tube (PMT) output. We tested delivery of d-luciferin via a subcutaneous minipump and in the drinking water. We demonstrate spikes in bioluminescence associated with drinking bouts. Further, we demonstrate that a synthetic luciferase substrate, CycLuc1, can support circadian rhythms of bioluminescence, even when delivered at a lower concentration than d-luciferin, and can support longer-term studies. A small difference in phase of the PER2::LUC bioluminescence rhythms, with females phase leading males, can be detected with this technique. We share our analysis scripts and suggestions for further improvements in this method. This approach will be straightforward to apply to mice with tissue-specific reporters, allowing insights into responses of specific peripheral clocks to perturbations such as environmental or pharmacological manipulations.
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Affiliation(s)
| | - Wanqi Wang
- Neuroscience Program, Smith College, Northampton, Massachusetts
| | - Ivana William
- Neuroscience Program, Smith College, Northampton, Massachusetts
| | - Selma Tir
- Neuroscience Program, Smith College, Northampton, Massachusetts
| | - Innus Mohammad
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Chan Medical School, Worcester, Massachusetts
| | - Reja Javed
- Neuroscience Program, Smith College, Northampton, Massachusetts
| | - Stormi Smith
- Neuroscience Program, Smith College, Northampton, Massachusetts
| | - Yilin Cui
- Neuroscience Program, Smith College, Northampton, Massachusetts
| | | | - Dalilah Mora
- Neuroscience Program, Smith College, Northampton, Massachusetts
| | - Ciearra B Smith
- Graduate Program in Neuroscience, University of Massachusetts Chan Medical School, Worcester, Massachusetts.,Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts
| | - Vincent van der Vinne
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts.,Department of Biology, Williams College, Williamstown, Massachusetts
| | | | - Stephen C Miller
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Chan Medical School, Worcester, Massachusetts
| | - David R Weaver
- Graduate Program in Neuroscience, University of Massachusetts Chan Medical School, Worcester, Massachusetts.,Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts
| | - Tanya L Leise
- Department of Mathematics & Statistics, Amherst College, Amherst, Massachusetts
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8
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Walbeek TJ, Harrison EM, Gorman MR, Glickman GL. Naturalistic Intensities of Light at Night: A Review of the Potent Effects of Very Dim Light on Circadian Responses and Considerations for Translational Research. Front Neurol 2021; 12:625334. [PMID: 33597916 PMCID: PMC7882611 DOI: 10.3389/fneur.2021.625334] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 01/06/2021] [Indexed: 12/16/2022] Open
Abstract
In this review, we discuss the remarkable potency and potential applications of a form of light that is often overlooked in a circadian context: naturalistic levels of dim light at night (nLAN), equivalent to intensities produced by the moon and stars. It is often assumed that such low levels of light do not produce circadian responses typically associated with brighter light levels. A solid understanding of the impacts of very low light levels is complicated further by the broad use of the somewhat ambiguous term “dim light,” which has been used to describe light levels ranging seven orders of magnitude. Here, we lay out the argument that nLAN exerts potent circadian effects on numerous mammalian species, and that given conservation of anatomy and function, the efficacy of light in this range in humans warrants further investigation. We also provide recommendations for the field of chronobiological research, including minimum requirements for the measurement and reporting of light, standardization of terminology (specifically as it pertains to “dim” light), and ideas for reconsidering old data and designing new studies.
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Affiliation(s)
- Thijs J Walbeek
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, United States.,Oregon Institute of Occupational Health Sciences, Oregon Health and Science University, Portland, OR, United States
| | - Elizabeth M Harrison
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, United States
| | - Michael R Gorman
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, United States.,Department of Psychology, University of California, San Diego, San Diego, CA, United States
| | - Gena L Glickman
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, United States.,Departments of Psychiatry and Neuroscience, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
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9
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Luo PH, Shu YM, Ni RJ, Liu YJ, Zhou JN. A Characteristic Expression Pattern of Core Circadian Genes in the Diurnal Tree Shrew. Neuroscience 2020; 437:145-160. [PMID: 32339628 DOI: 10.1016/j.neuroscience.2020.04.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 04/16/2020] [Accepted: 04/17/2020] [Indexed: 02/08/2023]
Abstract
The day-active tree shrew may serve as an animal model of human-like diurnal rhythms. However, the molecular basis for circadian rhythms in this species has remained unclear. In the present study, we investigated the expression patterns of core circadian genes involved in transcriptional/translational feedback loops (TTFLs) in both central and peripheral tissues of the tree shrew. The expression of 12 core circadian genes exhibited similar rhythmic patterns in the olfactory bulb, prefrontal cortex, hippocampus, and cerebellum, while the hypothalamus exhibited the weakest oscillations. The rhythms in peripheral tissues, especially the liver, were much more robust than those in brain tissues. ARNTL and NPAS2 were weakly rhythmic in brain tissues but exhibited almost the strongest rhythmicity in peripheral tissues. CLOCK and CRY2 exhibited the weakest rhythms in both central and peripheral tissues, while NR1D1 and CIART exhibited robust rhythms in both tissues. Most of these circadian genes were highly expressed at light/dark transitions in both brain and peripheral tissues, such as ARNTL and NPAS2 peaking at dusk while PERs peaking at dawn. Additionally, the peripheral clock was phase-advanced relative to the brain clock, as there was a significant advance (2-4 h) for PER3, DBP, NR1D1 and NR1D2. Furthermore, these genes exhibited an anti-phasic relationship between the diurnal tree shrew and the nocturnal mouse (i.e., 12-h phasing differential). Collectively, our findings demonstrate a characteristic expression pattern of core circadian genes in the tree shrew, which may provide a means for elucidating molecular mechanisms of diurnal rhythms.
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Affiliation(s)
- Peng-Hao Luo
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Yu-Mian Shu
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei, China; School of Architecture and Civil Engineering, Chengdu University, Chengdu, China
| | - Rong-Jun Ni
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei, China; Psychiatric Laboratory and Mental Health Center, West China Hospital of Sichuan University, Chengdu, China
| | - Ya-Jing Liu
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei, China; Department of Obstetrics and Gynecology, Center for Reproductive Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Jiang-Ning Zhou
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei, China.
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10
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Walbeek TJ, Harrison EM, Soler RR, Gorman MR. Enhanced Circadian Entrainment in Mice and Its Utility under Human Shiftwork Schedules. Clocks Sleep 2019; 1:394-413. [PMID: 33089177 PMCID: PMC7445835 DOI: 10.3390/clockssleep1030032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 08/20/2019] [Indexed: 12/21/2022] Open
Abstract
The circadian system is generally considered to be incapable of adjusting to rapid changes in sleep/work demands. In shiftworkers this leads to chronic circadian disruption and sleep loss, which together predict underperformance at work and negative health consequences. Two distinct experimental protocols have been proposed to increase circadian flexibility in rodents using dim light at night: rhythm bifurcation and T-cycle (i.e., day length) entrainment. Successful translation of such protocols to human shiftworkers could facilitate alignment of internal time with external demands. To assess entrainment flexibility following bifurcation and exposure to T-cycles, mice in Study 1 were repeatedly phase-shifted. Mice from experimental conditions rapidly phase-shifted their activity, while control mice showed expected transient misalignment. In Study 2 and 3, mice followed a several weeks-long intervention designed to model a modified DuPont or Continental shiftwork schedule, respectively. For both schedules, bifurcation and nocturnal dim lighting reduced circadian misalignment. Together, these studies demonstrate proof of concept that mammalian circadian systems can be rendered sufficiently flexible to adapt to multiple, rapidly changing shiftwork schedules. Flexible adaptation to exotic light-dark cycles likely relies on entrainment mechanisms that are distinct from traditional entrainment.
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Affiliation(s)
- Thijs J. Walbeek
- Department of Psychology, University of California San Diego, La Jolla, CA 92093, USA
- Center for Circadian Biology, University of California San Diego, La Jolla, CA 92093, USA
- Correspondence: (T.J.W.); (M.R.G.); Tel.: +1-858-822-2466 (M.R.G.)
| | - Elizabeth M. Harrison
- Department of Psychology, University of California San Diego, La Jolla, CA 92093, USA
- Center for Circadian Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Robert R. Soler
- Department of Psychology, University of California San Diego, La Jolla, CA 92093, USA
| | - Michael R. Gorman
- Department of Psychology, University of California San Diego, La Jolla, CA 92093, USA
- Center for Circadian Biology, University of California San Diego, La Jolla, CA 92093, USA
- Correspondence: (T.J.W.); (M.R.G.); Tel.: +1-858-822-2466 (M.R.G.)
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11
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Sun J, Joye DAM, Farkas AH, Gorman MR. Photoperiodic Requirements for Induction and Maintenance of Rhythm Bifurcation and Extraordinary Entrainment in Male Mice. Clocks Sleep 2019; 1:290-305. [PMID: 33089170 PMCID: PMC7445826 DOI: 10.3390/clockssleep1030025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 06/27/2019] [Indexed: 11/18/2022] Open
Abstract
Exposure of mice to a 24 h light:dark:light:dark (LDLD) cycle with dimly illuminated nights induces the circadian timing system to program two intervals of activity and two intervals of rest per 24 h cycle and subsequently allows entrainment to a variety of extraordinary light regimens including 30 h LDLD cycles. Little is known about critical lighting requirements to induce and maintain this non-standard entrainment pattern, termed “bifurcation,” and to enhance the range of apparent entrainment. The current study determined the necessary duration of the photophase for animals to bifurcate and assessed whether requirements for maintenance differed from those for induction. An objective index of bifurcated entrainment varied with length of the photophase over 4–10 h durations, with highest values at 8 h. To assess photic requirements for the maintenance of bifurcation, mice from each group were subsequently exposed to the LDLD cycle with 4 h photophases. While insufficient to induce bifurcation, this photoperiod maintained bifurcation in mice transferred from inductive LDLD cycles. Entrainment to 30 h LDLD cycles also varied with photoperiod duration. These studies characterize non-invasive tools that reveal latent flexibility in the circadian control of rest/activity cycles with important translational potential for addressing needs of human shift-workers.
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12
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Leise TL, Goldberg A, Michael J, Montoya G, Solow S, Molyneux P, Vetrivelan R, Harrington ME. Recurring circadian disruption alters circadian clock sensitivity to resetting. Eur J Neurosci 2018; 51:2343-2354. [PMID: 30269396 DOI: 10.1111/ejn.14179] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 09/06/2018] [Accepted: 09/17/2018] [Indexed: 01/12/2023]
Abstract
A single phase advance of the light:dark (LD) cycle can temporarily disrupt synchrony of neural circadian rhythms within the suprachiasmatic nucleus (SCN) and between the SCN and peripheral tissues. Compounding this, modern life can involve repeated disruptive light conditions. To model chronic disruption to the circadian system, we exposed male mice to more than a month of a 20-hr light cycle (LD10:10), which mice typically cannot entrain to. Control animals were housed under LD12:12. We measured locomotor activity and body temperature rhythms in vivo, and rhythms of PER2::LUC bioluminescence in SCN and peripheral tissues ex vivo. Unexpectedly, we discovered strong effects of the time of dissection on circadian phase of PER2::LUC bioluminescent rhythms, which varied across tissues. White adipose tissue was strongly reset by dissection, while thymus phase appeared independent of dissection timing. Prior light exposure impacted the SCN, resulting in strong resetting of SCN phase by dissection for mice housed under LD10:10, and weak phase shifts by time of dissection in SCN from control LD12:12 mice. These findings suggest that exposure to circadian disruption may desynchronize SCN neurons, increasing network sensitivity to perturbations. We propose that tissues with a weakened circadian network, such as the SCN under disruptive light conditions, or with little to no coupling, for example, some peripheral tissues, will show increased resetting effects. In particular, exposure to light at inconsistent circadian times on a recurring weekly basis disrupts circadian rhythms and alters sensitivity of the SCN neural pacemaker to dissection time.
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Affiliation(s)
- Tanya L Leise
- Department of Mathematics and Statistics, Amherst College, Amherst, Massachusetts
| | - Ariella Goldberg
- Department of Mathematics and Statistics, Amherst College, Amherst, Massachusetts
| | - John Michael
- Department of Mathematics and Statistics, Amherst College, Amherst, Massachusetts
| | - Grace Montoya
- Department of Mathematics and Statistics, Amherst College, Amherst, Massachusetts
| | - Sabrina Solow
- Department of Mathematics and Statistics, Amherst College, Amherst, Massachusetts
| | - Penny Molyneux
- Neuroscience Program, Smith College, Northampton, Massachusetts
| | - Ramalingam Vetrivelan
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts
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