1
|
Clancy BM, Theriault BR, Turcios R, Langan GP, Luchins KR. The Effect of Noise, Vibration, and Light Disturbances from Daily Health Checks on Breeding Performance, Nest Building, and Corticosterone in Mice. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE : JAALAS 2023; 62:291-302. [PMID: 37339873 PMCID: PMC10434751 DOI: 10.30802/aalas-jaalas-23-000002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 03/03/2023] [Accepted: 04/26/2023] [Indexed: 06/22/2023]
Abstract
At our institution, the techniques that technicians use for health checks vary for mice housed in cages on individually ventilated caging (IVC) racks. If the mice cannot be adequately visualized, some technicians partially undock the cage whereas others use an LED flashlight. These actions undoubtedly alter the cage microenvironment, particularly with regard to noise, vibration, and light, which are known to affect multiple welfare and research-related parameters in mice. The central aim of this study was to assess the effects of partial cage undocking and LED flashlight use during daily health checks on fecundity, nest building scores, and hair corticosterone concentrations in C57BL/6J mice to determine the least disturbing method of performing these health checks. In addition, we used an accelerometer, a microphone, and a light meter to measure intracage noise, vibration, and light under each condition. Breeding pairs (n = 100 pairs) were randomly assigned to one of 3 health check groups: partial undocking, LED flashlight, or control (in which mice were observed without any cage manipulation). We hypothesized that mice exposed to a flashlight or cage undocking during daily health checks would have fewer pups, poorer nest building scores, and higher hair corticosterone levels than did the control mice. We found no statistically significant difference in fecundity, nest building scores, or hair corticosterone levels between either experimental group as compared with the control group. However, hair corticosterone levels were significantly affected by the cage height on the rack and the amount of time on study. These results indicate that a short duration, once-daily exposure to partial cage undocking or to an LED flashlight during daily healthy checks does not affect breeding performance or wellbeing, as measured by nest scores and hair corticosterone levels, in C57BL/6J mice.
Collapse
Affiliation(s)
- Bridget M Clancy
- Animal Resources Center and Department of Surgery, The University of Chicago, Chicago, Illinois
| | - Betty R Theriault
- Animal Resources Center and Department of Surgery, The University of Chicago, Chicago, Illinois
| | - Rebecca Turcios
- Animal Resources Center and Department of Surgery, The University of Chicago, Chicago, Illinois
| | - George P Langan
- Animal Resources Center and Department of Surgery, The University of Chicago, Chicago, Illinois
| | - Kerith R Luchins
- Animal Resources Center and Department of Surgery, The University of Chicago, Chicago, Illinois
| |
Collapse
|
2
|
Dulko E, Jedrusiak M, Osuru HP, Atluri N, Illendula M, Davis EM, Beenhakker MP, Lunardi N. Sleep Fragmentation, Electroencephalographic Slowing, and Circadian Disarray in a Mouse Model for Intensive Care Unit Delirium. Anesth Analg 2023; 137:209-220. [PMID: 37192134 DOI: 10.1213/ane.0000000000006524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
BACKGROUND We aimed to further validate our previously published animal model for delirium by testing the hypothesis that in aged mice, Anesthesia, Surgery and simulated ICU conditions (ASI) induce sleep fragmentation, electroencephalographic (EEG) slowing, and circadian disarray consistent with intensive care unit (ICU) patients with delirium. METHODS A total of 41 mice were used. Mice were implanted with EEG electrodes and randomized to ASI or control groups. ASI mice received laparotomy, anesthesia, and simulated ICU conditions. Controls did not receive ASI. Sleep was recorded at the end of ICU conditions, and hippocampal tissue was collected on EEG recording. Arousals, EEG dynamics, and circadian gene expression were compared with t tests. Two-way repeated measures analysis of variance (RM ANOVA) was used to assess sleep according to light. RESULTS ASI mice experienced frequent arousals (36.6 ± 3.2 vs 26.5 ± 3.4; P = .044; 95% confidence interval [CI], 0.29-19.79; difference in mean ± SEM, 10.04 ± 4.62) and EEG slowing (frontal theta ratio, 0.223 ± 0.010 vs 0.272 ± 0.019; P = .026; 95% CI, -0.091 to -0.007; difference in mean ± SEM, -0.05 ± 0.02) relative to controls. In ASI mice with low theta ratio, EEG slowing was associated with a higher percentage of quiet wakefulness (38.2 ± 3.6 vs 13.4 ± 3.8; P = .0002; 95% CI, -35.87 to -13.84; difference in mean ± SEM, -24.86 ± 5.19). ASI mice slept longer during the dark phases of the circadian cycle (nonrapid eye movement [NREM], dark phase 1 [D1]: 138.9 ± 8.1 minutes vs 79.6 ± 9.6 minutes, P = .0003, 95% CI, -95.87 to -22.69, predicted mean difference ± SE: -59.28 ± 13.89; NREM, dark phase 2 (D2): 159.3 ± 7.3 minutes vs 112.6 ± 15.5 minutes, P = .006, 95% CI, -83.25 to -10.07, mean difference ± SE, -46.66 ± 13.89; rapid eye movement (REM), D1: 20.5 ± 2.1 minutes vs 5.8 ± 0.8 minutes, P = .001, 95% CI, -24.60 to -4.71, mean difference ± SE, -14. 65 ± 3.77; REM, D2: 21.0 ± 2.2 minutes vs 10.3 ± 1.4 minutes, P = .029, 95% CI, -20.64 to -0.76, mean difference ± SE, -10.70 ± 3.77). The expression of essential circadian genes was also lower in ASI mice (basic helix-loop-helix ARNT like [BMAL1] : -1.3 fold change; circadian locomotor output cycles protein kaput [CLOCK] : -1.2). CONCLUSIONS ASI mice experienced EEG and circadian changes mimicking those of delirious ICU patients. These findings support further exploration of this mouse approach to characterize the neurobiology of delirium.
Collapse
Affiliation(s)
| | | | | | | | | | | | - Mark P Beenhakker
- Pharmacology, University of Virginia Health, Charlottesville, Virginia
| | | |
Collapse
|
3
|
Starnes AN, Jones JR. Inputs and Outputs of the Mammalian Circadian Clock. BIOLOGY 2023; 12:biology12040508. [PMID: 37106709 PMCID: PMC10136320 DOI: 10.3390/biology12040508] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 03/16/2023] [Accepted: 03/24/2023] [Indexed: 03/30/2023]
Abstract
Circadian rhythms in mammals are coordinated by the central circadian pacemaker, the suprachiasmatic nucleus (SCN). Light and other environmental inputs change the timing of the SCN neural network oscillator, which, in turn, sends output signals that entrain daily behavioral and physiological rhythms. While much is known about the molecular, neuronal, and network properties of the SCN itself, the circuits linking the outside world to the SCN and the SCN to rhythmic outputs are understudied. In this article, we review our current understanding of the synaptic and non-synaptic inputs onto and outputs from the SCN. We propose that a more complete description of SCN connectivity is needed to better explain how rhythms in nearly all behaviors and physiological processes are generated and to determine how, mechanistically, these rhythms are disrupted by disease or lifestyle.
Collapse
|
4
|
Verma AK, Singh S, Rizvi SI. Aging, circadian disruption and neurodegeneration: Interesting interplay. Exp Gerontol 2023; 172:112076. [PMID: 36574855 DOI: 10.1016/j.exger.2022.112076] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 11/26/2022] [Accepted: 12/22/2022] [Indexed: 12/26/2022]
Abstract
The circadian system is an intricate molecular network of coordinating circadian clocks that organize the internal synchrony of the organism in response to the environment. These rhythms are maintained by genetically programmed positive and negative auto-regulated transcriptional and translational feedback loops that sustain 24-hour oscillations in mRNA and protein components of the endogenous circadian clock. Since inter and intracellular activity of the central pacemaker appears to reduce with aging, the interaction between the circadian clock and aging continues to elude our understanding. In this review article, we discuss circadian clock components at the molecular level and how aging adversely affects circadian clock functioning in rodents and humans. The natural decline in melatonin levels with aging strongly contributes to circadian dysregulation resulting in the development of neurological anomalies. Additionally, inappropriate environmental conditions such as Artificial Light at Night (ALAN) can cause circadian disruption or chronodisruption (CD) which can result in a variety of pathological diseases, including premature aging. Furthermore, we summarize recent evidence suggesting that CD may also be a predisposing factor for the development of age-related neurodegenerative diseases (NDDs) such as Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD), although more investigation is required to prove this link. Finally, certain chrono-enhancement approaches have been offered as intervention strategies to prevent, alleviate, or mitigate the impacts of CD. This review thus aims to bring together recent advancements in the chronobiology of the aging process, as well as its role in NDDs.
Collapse
Affiliation(s)
- Avnish Kumar Verma
- Department of Biochemistry, University of Allahabad, Allahabad 211002, India
| | - Sandeep Singh
- Department of Biochemistry, University of Allahabad, Allahabad 211002, India; Psychedelics Research Group, Biological Psychiatry Laboratory and Hadassah BrainLabs, Hadassah Medical Center, Hebrew University, Jerusalem, Israel
| | - Syed Ibrahim Rizvi
- Department of Biochemistry, University of Allahabad, Allahabad 211002, India.
| |
Collapse
|
5
|
Leone VA, Onishi KG, Kennedy M, Riggle JP, Pierre JF, Maneval AC, Spedale MN, Theriault BR, Chang EB, Prendergast BJ. Atypical behavioral and thermoregulatory circadian rhythms in mice lacking a microbiome. Sci Rep 2022; 12:14491. [PMID: 36008471 PMCID: PMC9411200 DOI: 10.1038/s41598-022-18291-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 08/09/2022] [Indexed: 12/17/2022] Open
Abstract
Trillions of microbial oscillators reside throughout the mammalian body, yet their contributions toward fundamental features of host circadian rhythms (CRs) have not been characterized. Here, we demonstrate that the microbiome contributes to host CRs in activity and thermoregulation. Mice devoid of microbes (germ-free, GF) exhibited higher-amplitude CRs in a light-dark cycle and longer circadian periods in constant darkness. Circadian entrainment to food was greater in GF mice, but resetting responses to simulated jet-lag were unaffected. Microbial transplantation with cecal contents of conventionally-raised mice normalized CRs of GF mice, indicating that the concurrent activity of gut microbes modulates host circadian networks. Obesogenic effects of high-fat diet were absent in GF mice, but some circadian-disruptive effects persisted. Transkingdom (host-microbe) interactions affect circadian period and entrainment of CRs in diverse traits, and microbes alter interactions among light- and food-entrainable circadian processes in the face of environmental (light, diet) perturbations.
Collapse
Affiliation(s)
- Vanessa A Leone
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, 1933 Observatory Dr., Madison, WI, 53706, USA.
- Department of Medicine, University of Chicago, Chicago, IL, 60637, USA.
| | - Kenneth G Onishi
- Department of Psychology, Institute for Mind and Biology, University of Chicago, 940 E 57th St., Chicago, IL, 60637, USA.
| | - Megan Kennedy
- Medical Scientist Training Program, University of Chicago, Chicago, IL, 60637, USA
- Department of Ecology and Evolution, University of Chicago, Chicago, IL, 60637, USA
| | - Jonathan P Riggle
- Department of Psychology, Institute for Mind and Biology, University of Chicago, 940 E 57th St., Chicago, IL, 60637, USA
| | - Joseph F Pierre
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Andrew C Maneval
- Department of Psychology, Institute for Mind and Biology, University of Chicago, 940 E 57th St., Chicago, IL, 60637, USA
| | - Melanie N Spedale
- Animal Resources Center, The University of Chicago, Chicago, IL, 60637, USA
| | - Betty R Theriault
- Department of Surgery, University of Chicago, Chicago, IL, 60637, USA
| | - Eugene B Chang
- Department of Medicine, University of Chicago, Chicago, IL, 60637, USA
| | - Brian J Prendergast
- Department of Psychology, Institute for Mind and Biology, University of Chicago, 940 E 57th St., Chicago, IL, 60637, USA
| |
Collapse
|
6
|
Shkodina AD, Tan SC, Hasan MM, Abdelgawad M, Chopra H, Bilal M, Boiko DI, Tarianyk KA, Alexiou A. Roles of clock genes in the pathogenesis of Parkinson's disease. Ageing Res Rev 2022; 74:101554. [PMID: 34973458 DOI: 10.1016/j.arr.2021.101554] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 11/24/2021] [Accepted: 12/27/2021] [Indexed: 12/13/2022]
Abstract
Parkinson's disease (PD) is a common motor disorder that has become increasingly prevalent in the ageing population. Recent works have suggested that circadian rhythms disruption is a common event in PD patients. Clock genes regulate the circadian rhythm of biological processes in eukaryotic organisms, but their roles in PD remain unclear. Despite this, several lines of evidence point to the possibility that clock genes may have a significant impact on the development and progression of the disease. This review aims to consolidate recent understanding of the roles of clock genes in PD. We first summarized the findings of clock gene expression and epigenetic analyses in PD patients and animal models. We also discussed the potential contributory role of clock gene variants in the development of PD and/or its symptoms. We further reviewed the mechanisms by which clock genes affect mitochondrial dynamics as well as the rhythmic synthesis and secretion of endocrine hormones, the impairment of which may contribute to the development of PD. Finally, we discussed the limitations of the currently available studies, and suggested future potential studies to deepen our understanding of the roles of clock genes in PD pathogenesis.
Collapse
Affiliation(s)
| | - Shing Cheng Tan
- UKM Medical Molecular Biology Institute, Universiti Kebangsaan Malaysia, 56000 Cheras, Kuala Lumpur, Malaysia.
| | - Mohammad Mehedi Hasan
- Department of Biochemistry and Molecular Biology, Faculty of Life Science, Mawlana Bhashani Science and Technology University, Tangail 1902, Bangladesh
| | - Mai Abdelgawad
- Biotechnology and Life Sciences Department, Faculty of Postgraduate Studies for Advanced Sciences (PSAS), Beni-Suef University, Beni-Suef 62511, Egypt
| | - Hitesh Chopra
- Chitkara College of Pharmacy, Chitkara University, 140401 Punjab, India
| | - Muhammad Bilal
- College of Pharmacy, Liaquat University of Medical and Health Sciences, Jamshoro, Pakistan
| | | | | | - Athanasios Alexiou
- Novel Global Community Educational Foundation, Peterlee Place NSW2700, Australia; AFNP Med, Haidingergasse 29, 1030 Wien, Austria
| |
Collapse
|
7
|
Shkodina AD, Tan SC, Hasan MM, Abdelgawad M, Chopra H, Bilal M, Boiko DI, Tarianyk KA, Alexiou A. Roles of clock genes in the pathogenesis of Parkinson's disease. Ageing Res Rev 2022; 74:101554. [DOI: https:/doi.org/10.1016/j.arr.2021.101554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
|
8
|
Shkodina AD, Tan SC, Hasan MM, Abdelgawad M, Chopra H, Bilal M, Boiko DI, Tarianyk KA, Alexiou A. Roles of clock genes in the pathogenesis of Parkinson's disease. Ageing Res Rev 2022. [DOI: https://doi.org/10.1016/j.arr.2021.101554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
9
|
Ashton A, Foster RG, Jagannath A. Photic Entrainment of the Circadian System. Int J Mol Sci 2022; 23:ijms23020729. [PMID: 35054913 PMCID: PMC8775994 DOI: 10.3390/ijms23020729] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 12/17/2021] [Accepted: 12/22/2021] [Indexed: 01/27/2023] Open
Abstract
Circadian rhythms are essential for the survival of all organisms, enabling them to predict daily changes in the environment and time their behaviour appropriately. The molecular basis of such rhythms is the circadian clock, a self-sustaining molecular oscillator comprising a transcriptional–translational feedback loop. This must be continually readjusted to remain in alignment with the external world through a process termed entrainment, in which the phase of the master circadian clock in the suprachiasmatic nuclei (SCN) is adjusted in response to external time cues. In mammals, the primary time cue, or “zeitgeber”, is light, which inputs directly to the SCN where it is integrated with additional non-photic zeitgebers. The molecular mechanisms underlying photic entrainment are complex, comprising a number of regulatory factors. This review will outline the photoreception pathways mediating photic entrainment, and our current understanding of the molecular pathways that drive it in the SCN.
Collapse
|
10
|
Bittman EL. Anatomical Methods to Study the Suprachiasmatic Nucleus. Methods Mol Biol 2022; 2482:191-210. [PMID: 35610428 PMCID: PMC10752494 DOI: 10.1007/978-1-0716-2249-0_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The mammalian suprachiasmatic nucleus (SCN) functions as a master circadian pacemaker. In order to examine mechanisms by which it keeps time, entrains to periodic environmental signals (zeitgebers), and regulates subordinate oscillators elsewhere in the brain and in the periphery, a variety of molecular methods have been applied. Multiple label immunocytochemistry and in situ hybridization provide anatomical insights that complement physiological approaches (such as ex vivo electrophysiology and luminometry) widely used to study the SCN.The anatomical methods require interpretation of data gathered from groups of individual animals sacrificed at different time points. This imposes constraints on the design of the experiments that aim to observe changes that occur with circadian phase in free-running conditions. It is essential in such experiments to account for differences in the periods of the subjects. Nevertheless, it is possible to resolve intracellular colocalization and regional expression of functionally important transcripts and/or their peptide products that serve as neuromodulators or neurotransmitters. Armed with these tools and others, understanding of the mechanisms by which the hypothalamic pacemaker regulates circadian function is progressing apace.
Collapse
Affiliation(s)
- Eric L Bittman
- Department of Biology and Program in Neuroscience & Behavior, University of Massachusetts, Amherst, MA, USA.
| |
Collapse
|
11
|
Rohr KE, Inda T, Evans JA. Vasopressin Resets the Central Circadian Clock in a Manner Influenced by Sex and Vasoactive Intestinal Polypeptide Signaling. Neuroendocrinology 2022; 112:904-916. [PMID: 34856551 PMCID: PMC9160207 DOI: 10.1159/000521286] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 12/01/2021] [Indexed: 01/03/2023]
Abstract
BACKGROUND/AIMS Circadian rhythms in behavior and physiology are programmed by the suprachiasmatic nucleus (SCN) of the hypothalamus. A subset of SCN neurons produce the neuropeptide arginine vasopressin (AVP), but it remains unclear whether AVP signaling influences the SCN clock directly. METHODS Here, we test that AVP signaling acting through V1A and V1B receptors influences molecular rhythms in SCN neurons. V1 receptor agonists were applied ex vivo to PERIOD2::LUCIFERASE SCN slices, allowing for real-time monitoring of changes in molecular clock function. RESULTS V1A/B agonists reset the phase of the SCN molecular clock in a time-dependent manner, with larger magnitude responses by the female SCN. Further, we found evidence that both Gαq and Gαs signaling pathways interact with V1A/B-induced SCN resetting, and that this response requires vasoactive intestinal polypeptide (VIP) signaling. CONCLUSIONS Collectively, this work indicates that AVP signaling resets SCN molecular rhythms in conjunction with VIP signaling and in a manner influenced by sex. This highlights the utility of studying clock function in both sexes and suggests that signal integration in central clock circuits regulates emergent properties important for the control of daily rhythms in behavior and physiology.
Collapse
Affiliation(s)
| | | | - Jennifer A. Evans
- Corresponding author: 560 N 16 St, Schroeder Complex, Room 446, Milwaukee, WI 53233, Phone: 414 288-5732, Fax: 414-288-6564,
| |
Collapse
|
12
|
Kim S, McMahon DG. Light sets the brain's daily clock by regional quickening and slowing of the molecular clockworks at dawn and dusk. eLife 2021; 10:70137. [PMID: 34927581 PMCID: PMC8687663 DOI: 10.7554/elife.70137] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 12/11/2021] [Indexed: 12/15/2022] Open
Abstract
How daily clocks in the brain are set by light to local environmental time and encode the seasons is not fully understood. The suprachiasmatic nucleus (SCN) is a central circadian clock in mammals that orchestrates physiology and behavior in tune with daily and seasonal light cycles. Here, we have found that optogenetically simulated light input to explanted mouse SCN changes the waveform of the molecular clockworks from sinusoids in free-running conditions to highly asymmetrical shapes with accelerated synthetic (rising) phases and extended degradative (falling) phases marking clock advances and delays at simulated dawn and dusk. Daily waveform changes arise under ex vivo entrainment to simulated winter and summer photoperiods, and to non-24 hr periods. Ex vivo SCN imaging further suggests that acute waveform shifts are greatest in the ventrolateral SCN, while period effects are greatest in the dorsomedial SCN. Thus, circadian entrainment is encoded by SCN clock gene waveform changes that arise from spatiotemporally distinct intrinsic responses within the SCN neural network.
Collapse
Affiliation(s)
- Suil Kim
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, United States
| | - Douglas G McMahon
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, United States.,Department of Biological Sciences, Vanderbilt University, Nashville, United States
| |
Collapse
|
13
|
Alzate-Correa D, Aten S, Campbell MJ, Hoyt KR, Obrietan K. Light-induced changes in the suprachiasmatic nucleus transcriptome regulated by the ERK/MAPK pathway. PLoS One 2021; 16:e0249430. [PMID: 34191798 PMCID: PMC8244859 DOI: 10.1371/journal.pone.0249430] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 03/17/2021] [Indexed: 11/18/2022] Open
Abstract
The mammalian master circadian pacemaker within the suprachiasmatic nucleus (SCN) maintains tight entrainment to the 24 hr light/dark cycle via a sophisticated clock-gated rhythm in the responsiveness of the oscillator to light. A central event in this light entrainment process appears to be the rapid induction of gene expression via the ERK/MAPK pathway. Here, we used RNA array-based profiling in combination with pharmacological disruption methods to examine the contribution of ERK/MAPK signaling to light-evoked gene expression. Transient photic stimulation during the circadian night, but not during the circadian day, triggered marked changes in gene expression, with early-night light predominately leading to increased gene expression and late-night light predominately leading to gene downregulation. Functional analysis revealed that light-regulated genes are involved in a diversity of physiological processes, including DNA transcription, RNA translation, mRNA processing, synaptic plasticity and circadian timing. The disruption of MAPK signaling led to a marked reduction in light-evoked gene regulation during the early night (32/52 genes) and late night (190/191 genes); further, MAPK signaling was found to gate gene expression across the circadian cycle. Together, these experiments reveal potentially important insights into the transcriptional-based mechanisms by which the ERK/MAPK pathway regulates circadian clock timing and light-evoked clock entrainment.
Collapse
Affiliation(s)
- Diego Alzate-Correa
- Division of Pharmaceutics and Pharmacology, Ohio State University, Columbus, OH, United States of America
| | - Sydney Aten
- Department of Neuroscience, Ohio State University, Columbus, OH, United States of America
| | - Moray J. Campbell
- Division of Pharmaceutics and Pharmacology, Ohio State University, Columbus, OH, United States of America
| | - Kari R. Hoyt
- Division of Pharmaceutics and Pharmacology, Ohio State University, Columbus, OH, United States of America
| | - Karl Obrietan
- Department of Neuroscience, Ohio State University, Columbus, OH, United States of America
| |
Collapse
|
14
|
Uriu K, Tei H. Complementary phase responses via functional differentiation of dual negative feedback loops. PLoS Comput Biol 2021; 17:e1008774. [PMID: 33684114 PMCID: PMC7971863 DOI: 10.1371/journal.pcbi.1008774] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 03/18/2021] [Accepted: 02/05/2021] [Indexed: 11/18/2022] Open
Abstract
Multiple feedback loops are often found in gene regulations for various cellular functions. In mammalian circadian clocks, oscillations of Period1 (Per1) and Period2 (Per2) expression are caused by interacting negative feedback loops (NFLs) whose protein products with similar molecular functions repress each other. However, Per1 expression peaks earlier than Per2 in the pacemaker tissue, raising the question of whether the peak time difference reflects their different dynamical functions. Here, we address this question by analyzing phase responses of the circadian clock caused by light-induced transcription of both Per1 and Per2 mRNAs. Through mathematical analyses of dual NFLs, we show that phase advance is mainly driven by light inputs to the repressor with an earlier expression peak as Per1, whereas phase delay is driven by the other repressor with a later peak as Per2. Due to the complementary contributions to phase responses, the ratio of light-induced transcription rates between Per1 and Per2 determines the magnitude and direction of phase shifts at each time of day. Specifically, stronger Per1 light induction than Per2 results in a phase response curve (PRC) with a larger phase advance zone than delay zone as observed in rats and hamsters, whereas stronger Per2 induction causes a larger delay zone as observed in mice. Furthermore, the ratio of light-induced transcription rates required for entrainment is determined by the relation between the circadian and light-dark periods. Namely, if the autonomous period of a circadian clock is longer than the light-dark period, a larger light-induced transcription rate of Per1 than Per2 is required for entrainment, and vice versa. In short, the time difference between Per1 and Per2 expression peaks can differentiate their dynamical functions. The resultant complementary contributions to phase responses can determine entrainability of the circadian clock to the light-dark cycle.
Collapse
Affiliation(s)
- Koichiro Uriu
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Japan
- * E-mail:
| | - Hajime Tei
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Japan
| |
Collapse
|
15
|
Liu JA, Walton JC, DeVries AC, Nelson RJ. Disruptions of Circadian Rhythms and Thrombolytic Therapy During Ischemic Stroke Intervention. Front Neurosci 2021; 15:675732. [PMID: 34177452 PMCID: PMC8222607 DOI: 10.3389/fnins.2021.675732] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 05/11/2021] [Indexed: 11/24/2022] Open
Abstract
Several endogenous and exogenous factors interact to influence stroke occurrence, in turn contributing to discernable daily distribution patterns in the frequency and severity of cerebrovascular events. Specifically, strokes that occur during the morning tend to be more severe and are associated with elevated diastolic blood pressure, increased hospital stay, and worse outcomes, including mortality, compared to strokes that occur later in the day. Furthermore, disrupted circadian rhythms are linked to higher risk for stroke and play a role in stroke outcome. In this review, we discuss the interrelation among core clock genes and several factors contributing to ischemic outcomes, sources of disrupted circadian rhythms, the implications of disrupted circadian rhythms in foundational stroke scientific literature, followed by a review of clinical implications. In addition to highlighting the distinct daily pattern of onset, several aspects of physiology including immune response, endothelial/vascular and blood brain barrier function, and fibrinolysis are under circadian clock regulation; disrupted core clock gene expression patterns can adversely affect these physiological processes, leading to a prothrombotic state. Lastly, we discuss how the timing of ischemic onset increases morning resistance to thrombolytic therapy and the risk of hemorrhagic transformation.
Collapse
Affiliation(s)
- Jennifer A Liu
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, United States
| | - James C Walton
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, United States
| | - A Courtney DeVries
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, United States.,Department of Medicine, Division of Oncology/Hematology, West Virginia University, Morgantown, WV, United States.,West Virginia University Cancer Institute, West Virginia University, Morgantown, WV, United States
| | - Randy J Nelson
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, United States
| |
Collapse
|
16
|
Walker WH, Bumgarner JR, Walton JC, Liu JA, Meléndez-Fernández OH, Nelson RJ, DeVries AC. Light Pollution and Cancer. Int J Mol Sci 2020; 21:E9360. [PMID: 33302582 PMCID: PMC7764771 DOI: 10.3390/ijms21249360] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/04/2020] [Accepted: 12/06/2020] [Indexed: 01/03/2023] Open
Abstract
For many individuals in industrialized nations, the widespread adoption of electric lighting has dramatically affected the circadian organization of physiology and behavior. Although initially assumed to be innocuous, exposure to artificial light at night (ALAN) is associated with several disorders, including increased incidence of cancer, metabolic disorders, and mood disorders. Within this review, we present a brief overview of the molecular circadian clock system and the importance of maintaining fidelity to bright days and dark nights. We describe the interrelation between core clock genes and the cell cycle, as well as the contribution of clock genes to oncogenesis. Next, we review the clinical implications of disrupted circadian rhythms on cancer, followed by a section on the foundational science literature on the effects of light at night and cancer. Finally, we provide some strategies for mitigation of disrupted circadian rhythms to improve health.
Collapse
Affiliation(s)
- William H. Walker
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV 26506, USA; (J.R.B.); (J.C.W.); (J.A.L.); (O.H.M.-F.); (R.J.N.); (A.C.D.)
| | - Jacob R. Bumgarner
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV 26506, USA; (J.R.B.); (J.C.W.); (J.A.L.); (O.H.M.-F.); (R.J.N.); (A.C.D.)
| | - James C. Walton
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV 26506, USA; (J.R.B.); (J.C.W.); (J.A.L.); (O.H.M.-F.); (R.J.N.); (A.C.D.)
| | - Jennifer A. Liu
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV 26506, USA; (J.R.B.); (J.C.W.); (J.A.L.); (O.H.M.-F.); (R.J.N.); (A.C.D.)
| | - O. Hecmarie Meléndez-Fernández
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV 26506, USA; (J.R.B.); (J.C.W.); (J.A.L.); (O.H.M.-F.); (R.J.N.); (A.C.D.)
| | - Randy J. Nelson
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV 26506, USA; (J.R.B.); (J.C.W.); (J.A.L.); (O.H.M.-F.); (R.J.N.); (A.C.D.)
| | - A. Courtney DeVries
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV 26506, USA; (J.R.B.); (J.C.W.); (J.A.L.); (O.H.M.-F.); (R.J.N.); (A.C.D.)
- Department of Medicine, Division of Oncology/Hematology, West Virginia University, Morgantown, WV 26506, USA
- West Virginia University Cancer Institute, West Virginia University, Morgantown, WV 26506, USA
| |
Collapse
|
17
|
Tomiyama Y, Shinohara T, Matsuka M, Bando T, Mito T, Tomioka K. The role of clockwork orange in the circadian clock of the cricket Gryllus bimaculatus. ZOOLOGICAL LETTERS 2020; 6:12. [PMID: 33292692 PMCID: PMC7659126 DOI: 10.1186/s40851-020-00166-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 10/31/2020] [Indexed: 06/12/2023]
Abstract
The circadian clock generates rhythms of approximately 24 h through periodic expression of the clock genes. In insects, the major clock genes period (per) and timeless (tim) are rhythmically expressed upon their transactivation by CLOCK/CYCLE, with peak levels in the early night. In Drosophila, clockwork orange (cwo) is known to inhibit the transcription of per and tim during the daytime to enhance the amplitude of the rhythm, but its function in other insects is largely unknown. In this study, we investigated the role of cwo in the clock mechanism of the cricket Gryllus bimaculatus. The results of quantitative RT-PCR showed that under a light/dark (LD) cycle, cwo is rhythmically expressed in the optic lobe (lamina-medulla complex) and peaks during the night. When cwo was knocked down via RNA interference (RNAi), some crickets lost their locomotor rhythm, while others maintained a rhythm but exhibited a longer free-running period under constant darkness (DD). In cwoRNAi crickets, all clock genes except for cryptochrome 2 (cry2) showed arrhythmic expression under DD; under LD, some of the clock genes showed higher mRNA levels, and tim showed rhythmic expression with a delayed phase. Based on these results, we propose that cwo plays an important role in the cricket circadian clock.
Collapse
Affiliation(s)
- Yasuaki Tomiyama
- Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530 Japan
| | - Tsugumichi Shinohara
- Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530 Japan
| | - Mirai Matsuka
- Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530 Japan
| | - Tetsuya Bando
- Graduate School of Medicine, Dentistry and Pharmaceutical Science, Okayama University, Okayama, 700-8558 Japan
| | - Taro Mito
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, 770-8513 Japan
| | - Kenji Tomioka
- Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530 Japan
| |
Collapse
|
18
|
Fleury G, Masís‐Vargas A, Kalsbeek A. Metabolic Implications of Exposure to Light at Night: Lessons from Animal and Human Studies. Obesity (Silver Spring) 2020; 28 Suppl 1:S18-S28. [PMID: 32700826 PMCID: PMC7497102 DOI: 10.1002/oby.22807] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 03/13/2020] [Accepted: 03/14/2020] [Indexed: 02/06/2023]
Abstract
Lately, the incidence of overweight, obesity, and type 2 diabetes has shown a staggering increase. To prevent and treat these conditions, one must look at their etiology. As life on earth has evolved under the conditions of nature's 24-hour light/dark cycle, it seems likely that exposure to artificial light at night (LAN) would affect physiology. Indeed, ample evidence has shown that LAN impacts many metabolic parameters, at least partly via the biological clock in the suprachiasmatic nucleus of the hypothalamus. This review focuses on the impact of chronic and acute effects of LAN of different wavelengths on locomotor activity, food intake, the sleep/wake cycle, body temperature, melatonin, glucocorticoids, and glucose and lipid metabolism. While chronic LAN disturbs daily rhythms in these parameters, experiments using short-term LAN exposure also have shown acute negative effects in metabolically active peripheral tissues. Experiments using LAN of different wavelengths not only have indicated an important role for melanopsin, the photopigment found in intrinsically photosensitive retinal ganglion cells, but also provided evidence that each wavelength may have a specific impact on energy metabolism. Importantly, exposure to LAN has been shown to impact glucose homeostasis also in humans and to be associated with an increased incidence of overweight, obesity, and atherosclerosis.
Collapse
Affiliation(s)
- Giulia Fleury
- Department of Endocrinology and MetabolismAmsterdam UMCUniversity of AmsterdamAmsterdamthe Netherlands
| | - Anayanci Masís‐Vargas
- Department of Endocrinology and MetabolismAmsterdam UMCUniversity of AmsterdamAmsterdamthe Netherlands
- Hypothalamic Integration MechanismsNetherlands Institute for Neuroscience (NIN)Amsterdamthe Netherlands
- Institute of Cellular and Integrative Neurosciences (INCI)UPR‐3212 CNRSUniversity of StrasbourgStrasbourgFrance
| | - Andries Kalsbeek
- Department of Endocrinology and MetabolismAmsterdam UMCUniversity of AmsterdamAmsterdamthe Netherlands
- Hypothalamic Integration MechanismsNetherlands Institute for Neuroscience (NIN)Amsterdamthe Netherlands
| |
Collapse
|
19
|
Tackenberg MC, Hughey JJ, McMahon DG. Distinct Components of Photoperiodic Light Are Differentially Encoded by the Mammalian Circadian Clock. J Biol Rhythms 2020; 35:353-367. [PMID: 32527181 DOI: 10.1177/0748730420929217] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Seasonal light cycles influence multiple physiological functions and are mediated through photoperiodic encoding by the circadian system. Despite our knowledge of the strong connection between seasonal light input and downstream circadian changes, less is known about the specific components of seasonal light cycles that are encoded and induce persistent changes in the circadian system. Using combinations of 3 T cycles (23, 24, 26 h) and 2 photoperiods per T cycle (long and short, with duty cycles scaled to each T cycle), we investigate the after-effects of entrainment to these 6 light cycles. We measure locomotor behavior duration (α), period (τ), and entrained phase angle (ψ) in vivo and SCN phase distribution (σφ), τ, and ψ ex vivo to refine our understanding of critical light components for influencing particular circadian properties. We find that both photoperiod and T-cycle length drive determination of in vivo ψ but differentially influence after-effects in α and τ, with photoperiod driving changes in α and photoperiod length and T-cycle length combining to influence τ. Using skeleton photoperiods, we demonstrate that in vivo ψ is determined by both parametric and nonparametric components, while changes in α are driven nonparametrically. Within the ex vivo SCN, we find that ψ and σφ of the PER2∷LUCIFERASE rhythm follow closely with their likely behavioral counterparts (ψ and α of the locomotor activity rhythm) while also confirming previous reports of τ after-effects of gene expression rhythms showing negative correlations with behavioral τ after-effects in response to T cycles. We demonstrate that within-SCN σφ changes, thought to underlie α changes in vivo, are induced primarily nonparametrically. Taken together, our results demonstrate that distinct components of seasonal light input differentially influence ψ, α, and τ and suggest the possibility of separate mechanisms driving the persistent changes in circadian behaviors mediated by seasonal light.
Collapse
Affiliation(s)
| | - Jacob J Hughey
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee.,Department of Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Douglas G McMahon
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee.,Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee
| |
Collapse
|
20
|
Moustafa A. Effect of Light-Dark Cycle Misalignment on the Hypothalamic-Pituitary-Gonadal Axis, Testicular Oxidative Stress, and Expression of Clock Genes in Adult Male Rats. Int J Endocrinol 2020; 2020:1426846. [PMID: 33204259 PMCID: PMC7666629 DOI: 10.1155/2020/1426846] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/07/2020] [Accepted: 07/13/2020] [Indexed: 01/18/2023] Open
Abstract
This study investigated the influence of circadian misalignment on the male reproductive system. Adult Sprague-Dawley male rats were exposed to prolonged light (20 h light : 4 h dark) or prolonged darkness (4 h light : 20 h dark) for 12 consecutive weeks. The somatic index of seminal vesicles and prostates increased due to prolonged light exposure. Sperm count and motility were enhanced solely by prolonged light exposure, whereas the percentage of sperm abnormalities was reduced by both prolonged light and darkness. The serum levels of reproductive hormones (follicle-stimulating hormone, luteinizing hormone, testosterone, and prolactin) were elevated, and the estradiol level was reduced by long-term light and dark exposure. Testicular total antioxidant capacity and antioxidant enzyme activities were improved, and lipid peroxidation was inhibited following chronic exposure to light or dark. Chronic light exposure increased, but chronic darkness decreased, testicular nitric oxide production. The mRNA expression of the hypothalamic and testicular clock genes including PER1-2, CRY1-2, BMAL1, CLOCK, and Rev-Erbα was altered by circadian disruption. Prolonged light exposure decreased the levels of thyroid hormones and suppressed the mRNA expression of adiponectin receptors 1 and 2. The immunohistochemical expression of proliferating cell nuclear antigen was decreased only by chronic darkness. The present study thus provides new insights into the physiological changes associated with long-term exposure to light or darkness, in which the expression levels of various clock gene mRNAs are modulated, reproductive hormones are increased, and the antioxidant enzyme system is ameliorated as mechanisms of adaptation to chronic circadian disruption.
Collapse
Affiliation(s)
- Amira Moustafa
- Department of Physiology, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44519, Egypt
| |
Collapse
|
21
|
Manoogian ENC, Kumar A, Obed D, Bergan J, Bittman EL. Suprachiasmatic function in a circadian period mutant: Duper alters light-induced activation of vasoactive intestinal peptide cells and PERIOD1 immunostaining. Eur J Neurosci 2019; 48:3319-3334. [PMID: 30346078 DOI: 10.1111/ejn.14214] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 09/07/2018] [Accepted: 09/18/2018] [Indexed: 11/28/2022]
Abstract
Mammalian circadian rhythms are entrained by photic stimuli that are relayed by retinal projections to the core of the suprachiasmatic nucleus (SCN). Neuronal activation, as demonstrated by expression of the immediate early gene c-fos, leads to transcription of the core clock gene per1. The duper mutation in hamsters shortens circadian period and amplifies light-induced phase shifts. We performed two experiments to compare the number of c-FOS immunoreactive (ir) and PER1-ir cells, and the intensity of staining, in the SCN of wild-type (WT) and duper hamsters at various intervals after presentation of a 15-min light pulse in the early subjective night. Light-induced c-FOS-ir within 1 hr in the dorsocaudal SCN of duper, but not WT hamsters. In cells that express vasoactive intestinal peptide (VIP), which plays a critical role in synchronization of SCN cellular oscillators, light-induced c-FOS-ir was greater in duper than WT hamsters. After the light pulse, PER1-ir cells were found in more medial portions of the SCN than FOS-ir, and appeared with a longer latency and over a longer time course, in VIP cells of duper than wild-type hamsters. Our results indicate that the duper allele alters SCN function in ways that may contribute to changes in free running period and phase resetting.
Collapse
Affiliation(s)
- Emily N C Manoogian
- Program in Neuroscience and Behavior, University of Massachusetts, Amherst, Massachusetts
| | - Ajay Kumar
- Program in Neuroscience and Behavior, University of Massachusetts, Amherst, Massachusetts
| | - Doha Obed
- Department of Biology, University of Massachusetts, Amherst, Massachusetts
| | - Joseph Bergan
- Psychological and Brain Sciences and Program in Neuroscience and Behavior, University of Massachusetts, Amherst, Massachusetts
| | - Eric L Bittman
- Department of Biology, Program in Neuroscience and Behavior, University of Massachusetts, Amherst, Massachusetts
| |
Collapse
|
22
|
Abnormal Photic Entrainment to Phase-Delaying Stimuli in the R6/2 Mouse Model of Huntington's Disease, despite Retinal Responsiveness to Light. eNeuro 2019; 6:ENEURO.0088-19.2019. [PMID: 31744839 PMCID: PMC6905640 DOI: 10.1523/eneuro.0088-19.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 10/22/2019] [Accepted: 10/28/2019] [Indexed: 12/13/2022] Open
Abstract
The circadian clock located in the suprachiasmatic nucleus (SCN) in mammals entrains to ambient light via the retinal photoreceptors. This allows behavioral rhythms to change in synchrony with seasonal and daily changes in light period. Circadian rhythmicity is progressively disrupted in Huntington's disease (HD) and in HD mouse models such as the transgenic R6/2 line. Although retinal afferent inputs to the SCN are disrupted in R6/2 mice at late stages, they can respond to changes in light/dark cycles, as seen in jet lag and 23 h/d paradigms. To investigate photic entrainment and SCN function in R6/2 mice at different stages of disease, we first assessed the effect on locomotor activity of exposure to a 15 min light pulse given at different times of the day. We then placed the mice under five non-standard light conditions. These were light cycle regimes (T-cycles) of T21 (10.5 h light/dark), T22 (11 h light/dark), T26 (13 h light/dark), constant light, or constant dark. We found a progressive impairment in photic synchronization in R6/2 mice when the stimuli required the SCN to lengthen rhythms (phase-delaying light pulse, T26, or constant light), but normal synchronization to stimuli that required the SCN to shorten rhythms (phase-advancing light pulse and T22). Despite the behavioral abnormalities, we found that Per1 and c-fos gene expression remained photo-inducible in SCN of R6/2 mice. Both the endogenous drift of the R6/2 mouse SCN to shorter periods and its inability to adapt to phase-delaying changes will contribute to the HD circadian dysfunction.
Collapse
|
23
|
Pathak SS, Liu D, Li T, de Zavalia N, Zhu L, Li J, Karthikeyan R, Alain T, Liu AC, Storch KF, Kaufman RJ, Jin VX, Amir S, Sonenberg N, Cao R. The eIF2α Kinase GCN2 Modulates Period and Rhythmicity of the Circadian Clock by Translational Control of Atf4. Neuron 2019; 104:724-735.e6. [PMID: 31522764 PMCID: PMC6872934 DOI: 10.1016/j.neuron.2019.08.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 04/13/2019] [Accepted: 08/03/2019] [Indexed: 12/20/2022]
Abstract
The integrated stress response (ISR) is activated in response to diverse stress stimuli to maintain homeostasis in neurons. Central to this process is the phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α). Here, we report a critical role for ISR in regulating the mammalian circadian clock. The eIF2α kinase GCN2 rhythmically phosphorylates eIF2α in the suprachiasmatic circadian clock. Increased eIF2α phosphorylation shortens the circadian period in both fibroblasts and mice, whereas reduced eIF2α phosphorylation lengthens the circadian period and impairs circadian rhythmicity in animals. Mechanistically, phosphorylation of eIF2α promotes mRNA translation of Atf4. ATF4 binding motifs are identified in multiple clock genes, including Per2, Per3, Cry1, Cry2, and Clock. ATF4 binds to the TTGCAGCA motif in the Per2 promoter and activates its transcription. Together, these results demonstrate a significant role for ISR in circadian physiology and provide a potential link between dysregulated ISR and circadian dysfunction in brain diseases.
Collapse
Affiliation(s)
- Salil Saurav Pathak
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN 55812, USA
| | - Dong Liu
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN 55812, USA
| | - Tianbao Li
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Nuria de Zavalia
- Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, QC H4B 1R6, Canada
| | - Lei Zhu
- Douglas Mental Health University Institute and Department of Psychiatry, McGill University, Montreal, QC H4H 1R3, Canada
| | - Jin Li
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN 55812, USA
| | - Ramanujam Karthikeyan
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN 55812, USA
| | - Tommy Alain
- Children's Hospital of Eastern Ontario Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
| | - Andrew C Liu
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Kai-Florian Storch
- Douglas Mental Health University Institute and Department of Psychiatry, McGill University, Montreal, QC H4H 1R3, Canada
| | - Randal J Kaufman
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92307, USA
| | - Victor X Jin
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Shimon Amir
- Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, QC H4B 1R6, Canada.
| | - Nahum Sonenberg
- Department of Biochemistry and Goodman Cancer Research Center, McGill University, Montreal, QC H3A 1A3, Canada.
| | - Ruifeng Cao
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN 55812, USA; Department of Neuroscience, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
| |
Collapse
|
24
|
Circadian regulation of depression: A role for serotonin. Front Neuroendocrinol 2019; 54:100746. [PMID: 31002895 PMCID: PMC9826732 DOI: 10.1016/j.yfrne.2019.04.003] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 03/13/2019] [Accepted: 04/15/2019] [Indexed: 01/11/2023]
Abstract
Synchronizing circadian (24 h) rhythms in physiology and behavior with the environmental light-dark cycle is critical for maintaining optimal health. Dysregulation of the circadian system increases susceptibility to numerous pathological conditions including major depressive disorder. Stress is a common etiological factor in the development of depression and the circadian system is highly interconnected to stress-sensitive neurotransmitter systems such as the serotonin (5-hydroxytryptamine, 5-HT) system. Thus, here we propose that stress-induced perturbation of the 5-HT system disrupts circadian processes and increases susceptibility to depression. In this review, we first provide an overview of the basic components of the circadian system. Next, we discuss evidence that circadian dysfunction is associated with changes in mood in humans and rodent models. Finally, we provide evidence that 5-HT is a critical factor linking dysregulation of the circadian system and mood. Determining how these two systems interact may provide novel therapeutic targets for depression.
Collapse
|
25
|
Jagannath A, Taylor L, Wakaf Z, Vasudevan SR, Foster RG. The genetics of circadian rhythms, sleep and health. Hum Mol Genet 2018; 26:R128-R138. [PMID: 28977444 PMCID: PMC5886477 DOI: 10.1093/hmg/ddx240] [Citation(s) in RCA: 126] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 06/21/2017] [Indexed: 11/12/2022] Open
Abstract
Circadian rhythms are 24-h rhythms in physiology and behaviour generated by molecular clocks, which serve to coordinate internal time with the external world. The circadian system is a master regulator of nearly all physiology and its disruption has major consequences on health. Sleep and circadian rhythm disruption (SCRD) is a ubiquitous feature in today's 24/7 society, and studies on shift-workers have shown that SCRD can lead not only to cognitive impairment, but also metabolic syndrome and psychiatric illness including depression (1,2). Mouse models of clock mutants recapitulate these deficits, implicating mechanistic and causal links between SCRD and disease pathophysiology (3-5). Importantly, treating clock disruption reverses and attenuates these adverse health states in animal models (6,7), thus establishing the circadian system as a novel therapeutic target. Significantly, circadian and clock-controlled gene mutations have recently been identified by Genome-Wide Association Studies (GWAS) in the aetiology of sleep, mental health and metabolic disorders. This review will focus upon the genetics of circadian rhythms in sleep and health.
Collapse
Affiliation(s)
- Aarti Jagannath
- Sleep and Circadian Neuroscience Institute, OMPI-G, Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Lewis Taylor
- Sleep and Circadian Neuroscience Institute, OMPI-G, Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Zeinab Wakaf
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Sridhar R Vasudevan
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Russell G Foster
- Sleep and Circadian Neuroscience Institute, OMPI-G, Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| |
Collapse
|
26
|
Hsu YWA, Gile JJ, Perez JG, Morton G, Ben-Hamo M, Turner EE, de la Iglesia HO. The Dorsal Medial Habenula Minimally Impacts Circadian Regulation of Locomotor Activity and Sleep. J Biol Rhythms 2017; 32:444-455. [PMID: 28954569 DOI: 10.1177/0748730417730169] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
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 (dMHbCKO) 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. To test this hypothesis, we assessed the integrity of the circadian system in dMHbCKO mice. Here we show that the developmental lesion of the dMHb reduces WRA under both a light-dark cycle and constant darkness, increases the circadian period of WRA, but has no effect on the circadian amplitude or period of home cage activity or the daily amplitude of sleep stages, suggesting that the lengthening of period is a result of the decreased WRA in the mutant mice. Polysomnographic sleep recordings show that dMHbCKO mice have an overall unaltered daily amplitude of sleep stages but have fragmented sleep and an overall increase in total rapid eye movement (REM) sleep. Photoresponsiveness is intact in dMHbCKO mice, but compared with control animals, they reentrain faster to a 6-h abrupt phase delay protocol. Circadian changes in WRA of dMHbCKO mice do not appear to emerge within the central pacemaker, as circadian expression of the clock genes Per1 and Per2 within the SCN is normal. We do find some evidence for fragmented sleep and an overall increase in total REM sleep, supporting a model in which the dMHb is part of the neural circuitry encoding motivation and involved in the manifestation of some of the symptoms of depression.
Collapse
Affiliation(s)
- Yun-Wei A Hsu
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Jennifer J Gile
- Department of Biology and Graduate Program in Neuroscience, University of Washington, Seattle, Washington
| | - Jazmine G Perez
- Department of Biology and Graduate Program in Neuroscience, University of Washington, Seattle, Washington
| | - Glenn Morton
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Miriam Ben-Hamo
- Department of Biology and Graduate Program in Neuroscience, University of Washington, Seattle, Washington
| | - Eric E Turner
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington.,Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington
| | - Horacio O de la Iglesia
- Department of Biology and Graduate Program in Neuroscience, University of Washington, Seattle, Washington
| |
Collapse
|
27
|
Walbeek TJ, Gorman MR. Simple Lighting Manipulations Facilitate Behavioral Entrainment of Mice to 18-h Days. J Biol Rhythms 2017; 32:309-322. [PMID: 28770653 DOI: 10.1177/0748730417718347] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In an invariantly rhythmic world, a robust and stable mammalian circadian clock is presumed to confer fitness advantages. In shift-work or after rapid transmeridian travel, however, a stable clock might be maladaptive and a more flexibly resettable clock may have advantages. The rate at which rodents can adjust to simulated time zone travel and the range of entrainment can be markedly increased through simple light manipulations, namely, by exposing animals to extremely dim light (<0.01 lux) at night or by bifurcating rhythms under 24-h light-dark-light-dark (LDLD) cycles. Here we investigated the separate effects of dim light and bifurcation on the ability of mice to entrain to 18-h days (LD 13:5; T18). Incorporating dim light at night, mice in Experiment 1 were exposed either to LD cycles with photophases that were progressively shortened from LD 19:5 to LD 13:5 or to bifurcating LDLD cycles with photophases that were lengthened from LDLD 7:5:7:5 to LDLD 13:5:13:5. In both cases, wheel-running rhythms were robustly synchronized to T18 and the phase of the free-running circadian rhythm was controlled by the timing of release into constant conditions. In Experiment 2, either dimly illuminated nights or a history of bifurcation without continuing dim light was sufficient to allow behavioral entrainment to T18 whereas previously unbifurcated mice under dark nights failed to entrain to T18. Additionally, concurrent measurement of body temperature rhythms in T24 LDLD revealed them to be bimodal. These studies suggest that the circadian system is markedly more flexible than conventionally thought and that this flexibility can be achieved in a noninvasive and nonpharmacological way. Facilitation of behavioral entrainment to extreme light-dark cycles may have translational potential for human shift-workers.
Collapse
Affiliation(s)
- Thijs J Walbeek
- Department of Psychology and Center for Circadian Biology, University of California San Diego, La Jolla, California
| | - Michael R Gorman
- Department of Psychology and Center for Circadian Biology, University of California San Diego, La Jolla, California
| |
Collapse
|
28
|
Yan SS, Wang W. The effect of lens aging and cataract surgery on circadian rhythm. Int J Ophthalmol 2016; 9:1066-74. [PMID: 27500118 DOI: 10.18240/ijo.2016.07.21] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 02/14/2016] [Indexed: 12/31/2022] Open
Abstract
Many organisms have evolved an approximately 24-hour circadian rhythm that allows them to achieve internal physiological homeostasis with external environment. Suprachiasmatic nucleus (SCN) is the central pacemaker of circadian rhythm, and its activity is entrained to the external light-dark cycle. The SCN controls circadian rhythm through regulating the synthesis of melatonin by pineal gland via a multisynaptic pathway. Light, especially short-wavelength blue light, is the most potent environmental time cue in circadian photoentrainment. Recently, the discovery of a novel type of retinal photoreceptors, intrinsically photosensitive retinal ganglion cells, sheds light on the mechanism of circadian photoentrainment and raises concerns about the effect of ocular diseases on circadian system. With age, light transmittance is significantly decreased due to the aging of crystalline lens, thus possibly resulting in progressive loss of circadian photoreception. In the current review, we summarize the circadian physiology, highlight the important role of light in circadian rhythm regulation, discuss about the correlation between age-related cataract and sleep disorders, and compare the effect of blue light- filtering intraocular lenses (IOLs) and ultraviolet only filtering IOLs on circadian rhythm.
Collapse
Affiliation(s)
- Shen-Shen Yan
- Department of Ophthalmology, Peking University Third Hospital, Beijing 100191, China
| | - Wei Wang
- Department of Ophthalmology, Peking University Third Hospital, Beijing 100191, China
| |
Collapse
|
29
|
|
30
|
Ramkisoensing A, Meijer JH. Synchronization of Biological Clock Neurons by Light and Peripheral Feedback Systems Promotes Circadian Rhythms and Health. Front Neurol 2015; 6:128. [PMID: 26097465 PMCID: PMC4456861 DOI: 10.3389/fneur.2015.00128] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 05/19/2015] [Indexed: 12/16/2022] Open
Abstract
In mammals, the suprachiasmatic nucleus (SCN) functions as a circadian clock that drives 24-h rhythms in both physiology and behavior. The SCN is a multicellular oscillator in which individual neurons function as cell-autonomous oscillators. The production of a coherent output rhythm is dependent upon mutual synchronization among single cells and requires both synaptic communication and gap junctions. Changes in phase-synchronization between individual cells have consequences on the amplitude of the SCN’s electrical activity rhythm, and these changes play a major role in the ability to adapt to seasonal changes. Both aging and sleep deprivation negatively affect the circadian amplitude of the SCN, whereas behavioral activity (i.e., exercise) has a positive effect on amplitude. Given that the amplitude of the SCN’s electrical activity rhythm is essential for achieving robust rhythmicity in physiology and behavior, the mechanisms that underlie neuronal synchronization warrant further study. A growing body of evidence suggests that the functional integrity of the SCN contributes to health, well-being, cognitive performance, and alertness; in contrast, deterioration of the 24-h rhythm is a risk factor for neurodegenerative disease, cancer, depression, and sleep disorders.
Collapse
Affiliation(s)
- Ashna Ramkisoensing
- Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center , Leiden , Netherlands
| | - Johanna H Meijer
- Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center , Leiden , Netherlands
| |
Collapse
|
31
|
Beckwith EJ, Ceriani MF. Experimental assessment of the network properties of the Drosophila circadian clock. J Comp Neurol 2015; 523:982-96. [PMID: 25504089 DOI: 10.1002/cne.23728] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 12/09/2014] [Accepted: 12/09/2014] [Indexed: 01/03/2023]
Abstract
Circadian rhythms are conserved across kingdoms and coordinate physiology and behavior for appropriate time-keeping. The neuronal populations that govern circadian rhythms are described in many animal models, and the current challenge is to understand how they interact to control overt rhythms, remaining plastic enough to respond and adapt to a changing environment. In Drosophila melanogaster, the circadian network comprises about 150 neurons, and the main synchronizer is the neuropeptide pigment-dispersing factor (PDF), released by the well-characterized central pacemaker neurons, the small ventral lateral neurons (sLNvs). However, the rules and properties governing the communication and coupling between this central pacemaker and downstream clusters are not fully elucidated. Here we genetically manipulate the speed of the molecular clock specifically in the central pacemaker neurons of Drosophila and provide experimental evidence of their restricted ability to synchronize downstream clusters. We also demonstrate that the sLNv-controlled clusters have an asymmetric entrainment range and were able to experimentally assess it. Our data imply that different clusters are subjected to different coupling strengths, and display independent endogenous periods. Finally, the manipulation employed here establishes a suitable paradigm to test other network properties as well as the cell-autonomous mechanisms running in different circadian-relevant clusters.
Collapse
Affiliation(s)
- Esteban J Beckwith
- Behavioral Genetics Laboratory, Fundación Instituto Leloir, Institute for Biochemical Research, Buenos Aires-Argentine Research Council, Buenos Aires, 1405BWE, Argentina
| | | |
Collapse
|
32
|
Hughes S, Jagannath A, Hankins MW, Foster RG, Peirson SN. Photic regulation of clock systems. Methods Enzymol 2014; 552:125-43. [PMID: 25707275 DOI: 10.1016/bs.mie.2014.10.018] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Circadian rhythms in physiology and behavior provide a selective advantage by enabling organisms to anticipate rhythmic changes in their environment. These rhythms are based upon a molecular clock generated via an intracellular transcriptional-translational feedback loop involving a number of key clock genes. However, to be of practical use, circadian rhythms need to be entrained to the external environment. In mammals, the primary signal for entrainment is light detected by the photoreceptors of the eye. Research on the mechanisms of photic entrainment has identified a novel photoreceptor system in the retina, consisting of photosensitive retinal ganglion cells expressing the photopigment melanopsin. Light input from these retinal photoreceptors reaches the master circadian pacemaker in the suprachiasmatic nuclei (SCN) via the retinohypothalamic tract, where it then interacts with the molecular clock to bring about entrainment. This chapter focuses on the retinal photoreceptors mediating entrainment, and how light information from the retina is transmitted to the SCN, before detailing recent advances in our understanding of how the molecular clock within the SCN is regulated by light input. Finally, the primary assays that have been used to measure photic entrainment are described.
Collapse
Affiliation(s)
- Steven Hughes
- Sleep and Circadian Institute (SCNi), Nuffield Department of Clinical Neurosciences (Nuffield Laboratory of Ophthalmology), University of Oxford, Oxford, United Kingdom
| | - Aarti Jagannath
- Sleep and Circadian Institute (SCNi), Nuffield Department of Clinical Neurosciences (Nuffield Laboratory of Ophthalmology), University of Oxford, Oxford, United Kingdom
| | - Mark W Hankins
- Sleep and Circadian Institute (SCNi), Nuffield Department of Clinical Neurosciences (Nuffield Laboratory of Ophthalmology), University of Oxford, Oxford, United Kingdom
| | - Russell G Foster
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
| | - Stuart N Peirson
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
| |
Collapse
|
33
|
Ramkisoensing A, Gu C, van Engeldorp Gastelaars HMD, Michel S, Deboer T, Rohling JHT, Meijer JH. Enhanced phase resetting in the synchronized suprachiasmatic nucleus network. J Biol Rhythms 2014; 29:4-15. [PMID: 24492878 DOI: 10.1177/0748730413516750] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The suprachiasmatic nucleus (SCN) adapts to both the external light-dark (LD) cycle and seasonal changes in day length. In short photoperiods, single-cell activity patterns are tightly synchronized (i.e., in phase); in long photoperiods, these patterns are relatively dispersed, causing lower amplitude rhythms. The limit cycle oscillator has been used to describe the SCN's circadian rhythmicity and predicts that following a given perturbation, high-amplitude SCN rhythms will shift less than low-amplitude rhythms. Some studies reported, however, that phase delays are larger when animals are entrained to a short photoperiod. Because phase advances and delays are mediated by partially distinct (i.e., nonoverlapping) biochemical pathways, we investigated the effect of a 4-h phase advance of the LD cycle in mice housed in either short (LD 8:16) or long (LD 16:8) photoperiods. In vitro recordings revealed a significantly larger phase advance in the SCN of mice entrained to short as compared to long photoperiods (4.2 ± 0.3 h v. 1.4 ± 0.9 h, respectively). Surprisingly, in mice with long photoperiods, the behavioral phase shift was larger than the phase shift of the SCN (3.7 ± 0.4 h v. 1.4 ± 0.9 h, respectively). To exclude a confounding influence of running-wheel activity on the magnitude of the shifts of the SCN, we repeated the experiments in the absence of running wheels and found similar shifts in the SCN in vitro in short and long days (3.0 ± 0.5 h v. 0.4 ± 0.9 h, respectively). Interestingly, removal of the running wheel reduced the phase-shifting capacity of mice in long days, leading to similar behavioral shifts in short and long photoperiods (1.0 ± 0.1 h v. 1.0 ± 0.4 h). As the behavioral shifts in the presence of wheels were larger than the shift of the SCN, it is suggested that additional, non-SCN neuronal networks in the brain are involved in regulating the timing of behavioral activity. On the basis of the phase shifts observed in vitro, we conclude that highly synchronized SCN networks with high-amplitude rhythms show a larger phase-shifting capacity than desynchronized networks of low amplitude.
Collapse
Affiliation(s)
- Ashna Ramkisoensing
- Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, the Netherlands
| | | | | | | | | | | | | |
Collapse
|
34
|
Hasegawa Y, Arita M. Optimal implementations for reliable circadian clocks. PHYSICAL REVIEW LETTERS 2014; 113:108101. [PMID: 25238386 DOI: 10.1103/physrevlett.113.108101] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Indexed: 06/03/2023]
Abstract
Circadian rhythms are acquired through evolution to increase the chances for survival through synchronizing with the daylight cycle. Reliable synchronization is realized through two trade-off properties: regularity to keep time precisely, and entrainability to synchronize the internal time with daylight. We find by using a phase model with multiple inputs that achieving the maximal limit of regularity and entrainability entails many inherent features of the circadian mechanism. At the molecular level, we demonstrate the role sharing of two light inputs, phase advance and delay, as is well observed in mammals. At the behavioral level, the optimal phase-response curve inevitably contains a dead zone, a time during which light pulses neither advance nor delay the clock. We reproduce the results of phase-controlling experiments entrained by two types of periodic light pulses. Our results indicate that circadian clocks are designed optimally for reliable clockwork through evolution.
Collapse
Affiliation(s)
- Yoshihiko Hasegawa
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Masanori Arita
- Center for Information Biology, National Institute of Genetics, Shizuoka 411-8540, Japan and RIKEN Center for Sustainable Resource Science, Kanagawa 230-0045, Japan
| |
Collapse
|
35
|
Abstract
Most organisms display endogenously produced ∼ 24-hour fluctuations in physiology and behavior, termed circadian rhythms. Circadian rhythms are driven by a transcriptional-translational feedback loop that is hierarchically expressed throughout the brain and body, with the suprachiasmatic nucleus of the hypothalamus serving as the master circadian oscillator at the top of the hierarchy. Appropriate circadian regulation is important for many homeostatic functions including energy regulation. Multiple genes involved in nutrient metabolism display rhythmic oscillations, and metabolically related hormones such as glucagon, insulin, ghrelin, leptin, and corticosterone are released in a circadian fashion. Mice harboring mutations in circadian clock genes alter feeding behavior, endocrine signaling, and dietary fat absorption. Moreover, misalignment between behavioral and molecular circadian clocks can result in obesity in both rodents and humans. Importantly, circadian rhythms are most potently synchronized to the external environment by light information and exposure to light at night potentially disrupts circadian system function. Since the advent of electric lights around the turn of the 20th century, exposure to artificial and irregular light schedules has become commonplace. The increase in exposure to light at night parallels the global increase in the prevalence of obesity and metabolic disorders. In this review, we propose that exposure to light at night alters metabolic function through disruption of the circadian system. We first provide an introduction to the circadian system, with a specific emphasis on the effects of light on circadian rhythms. Next we address interactions between the circadian system and metabolism. Finally, we review current experimental and epidemiological work directly associating exposure to light at night and metabolism.
Collapse
Affiliation(s)
- Laura K Fonken
- Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, Ohio 43210
| | | |
Collapse
|
36
|
Husse J, Leliavski A, Tsang AH, Oster H, Eichele G. The light-dark cycle controls peripheral rhythmicity in mice with a genetically ablated suprachiasmatic nucleus clock. FASEB J 2014; 28:4950-60. [PMID: 25063847 DOI: 10.1096/fj.14-256594] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The mammalian circadian timing system consists of a master pacemaker in the suprachiasmatic nucleus (SCN), which is thought to synchronize peripheral clocks in various organs with each other and with external time. Our knowledge about the role of the SCN clock is based mainly on SCN lesion and transplantation studies. We have now directly deleted the SCN clock using the Cre/LoxP system and investigated how this affects synchronization of peripheral rhythms. Impaired locomotor activity and arrhythmic clock gene expression in the SCN confirm that the SCN clockwork was efficiently abolished in our mouse model. Nonetheless, under light-dark (LD) conditions, peripheral clocks remained rhythmic and synchronized to the LD cycle, and phase relationships between peripheral clocks were sustained. Adaptation to a shifted LD cycle was accelerated in SCN clock-deficient mice. Moreover, under zeitgeber-free conditions, rhythmicity of the peripheral clock gene expression was initially dampened, and after several days peripheral clocks were desynchronized. These findings suggest that the SCN clock is dispensable for the synchronization of peripheral clocks to the LD cycle. A model describing an SCN clock-independent pathway that synchronizes peripheral clocks with the LD cycle is discussed.
Collapse
Affiliation(s)
- Jana Husse
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Alexei Leliavski
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Anthony H Tsang
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Henrik Oster
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Gregor Eichele
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| |
Collapse
|
37
|
Gooley JJ, Chua ECP. Diurnal regulation of lipid metabolism and applications of circadian lipidomics. J Genet Genomics 2014; 41:231-50. [PMID: 24894351 DOI: 10.1016/j.jgg.2014.04.001] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 04/10/2014] [Accepted: 04/10/2014] [Indexed: 02/04/2023]
Abstract
The circadian timing system plays a key role in orchestrating lipid metabolism. In concert with the solar cycle, the circadian system ensures that daily rhythms in lipid absorption, storage, and transport are temporally coordinated with rest-activity and feeding cycles. At the cellular level, genes involved in lipid synthesis and fatty acid oxidation are rhythmically activated and repressed by core clock proteins in a tissue-specific manner. Consequently, loss of clock gene function or misalignment of circadian rhythms with feeding cycles (e.g., in shift work) results in impaired lipid homeostasis. Herein, we review recent progress in circadian rhythms research using lipidomics, i.e., large-scale profiling of lipid metabolites, to characterize circadian-regulated lipid pathways in mammals. In mice, novel regulatory circuits involved in fatty acid metabolism have been identified in adipose tissue, liver, and muscle. Extensive diversity in circadian regulation of plasma lipids has also been revealed in humans using lipidomics and other metabolomics approaches. In future studies, lipidomics platforms will be increasingly used to better understand the effects of genetic variation, shift work, food intake, and drugs on circadian-regulated lipid pathways and metabolic health.
Collapse
Affiliation(s)
- Joshua J Gooley
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Graduate Medical School, Singapore 169857, Singapore; Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston 02115, USA; Division of Sleep Medicine, Harvard Medical School, Boston 02115, USA.
| | - Eric Chern-Pin Chua
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Graduate Medical School, Singapore 169857, Singapore
| |
Collapse
|
38
|
Spoelstra K, Comas M, Daan S. Compression of daily activity time in mice lacking functionalPerorCrygenes. Chronobiol Int 2014; 31:645-54. [DOI: 10.3109/07420528.2014.885529] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- K Spoelstra
- Unit of Chronobiology, University of Groningen , Groningen , The Netherlands
| | | | | |
Collapse
|
39
|
Adachi AA, Fujioka A, Nagano M, Masumoto KH, Takumi T, Yoshimura T, Ebihara S, Mori K, Yokota Y, Shigeyoshi Y. Helix-loop-helix Protein Id2 Stabilizes Mammalian Circadian Oscillation Under Constant Light Conditions. Zoolog Sci 2013; 30:1011-8. [DOI: 10.2108/zsj.30.1011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
40
|
Jagannath A, Butler R, Godinho SIH, Couch Y, Brown LA, Vasudevan SR, Flanagan KC, Anthony D, Churchill GC, Wood MJA, Steiner G, Ebeling M, Hossbach M, Wettstein JG, Duffield GE, Gatti S, Hankins MW, Foster RG, Peirson SN. The CRTC1-SIK1 pathway regulates entrainment of the circadian clock. Cell 2013; 154:1100-1111. [PMID: 23993098 PMCID: PMC3898689 DOI: 10.1016/j.cell.2013.08.004] [Citation(s) in RCA: 144] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 05/24/2013] [Accepted: 07/29/2013] [Indexed: 11/09/2022]
Abstract
Retinal photoreceptors entrain the circadian system to the solar day. This photic resetting involves cAMP response element binding protein (CREB)-mediated upregulation of Per genes within individual cells of the suprachiasmatic nuclei (SCN). Our detailed understanding of this pathway is poor, and it remains unclear why entrainment to a new time zone takes several days. By analyzing the light-regulated transcriptome of the SCN, we have identified a key role for salt inducible kinase 1 (SIK1) and CREB-regulated transcription coactivator 1 (CRTC1) in clock re-setting. An entrainment stimulus causes CRTC1 to coactivate CREB, inducing the expression of Per1 and Sik1. SIK1 then inhibits further shifts of the clock by phosphorylation and deactivation of CRTC1. Knockdown of Sik1 within the SCN results in increased behavioral phase shifts and rapid re-entrainment following experimental jet lag. Thus SIK1 provides negative feedback, acting to suppress the effects of light on the clock. This pathway provides a potential target for the regulation of circadian rhythms. Nocturnal light induces widespread transcriptional changes in the SCN The CRTC1-SIK1 cascade regulates entrainment of the circadian clock Negative feedback by SIK1 limits the effects of light on the clock Homeostatic regulation of entrainment ensures gradual adaptation to a new time zone
Collapse
Affiliation(s)
- Aarti Jagannath
- Nuffield Department of Clinical Neurosciences (Nuffield Laboratory of Ophthalmology), University of Oxford, Levels 5-6 West Wing, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK; pRED Pharma Research and Development F. Hoffmann-La Roche, 4070 Basel, Switzerland
| | - Rachel Butler
- Nuffield Department of Clinical Neurosciences (Nuffield Laboratory of Ophthalmology), University of Oxford, Levels 5-6 West Wing, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK; pRED Pharma Research and Development F. Hoffmann-La Roche, 4070 Basel, Switzerland
| | - Sofia I H Godinho
- Nuffield Department of Clinical Neurosciences (Nuffield Laboratory of Ophthalmology), University of Oxford, Levels 5-6 West Wing, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK; pRED Pharma Research and Development F. Hoffmann-La Roche, 4070 Basel, Switzerland
| | - Yvonne Couch
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Laurence A Brown
- Nuffield Department of Clinical Neurosciences (Nuffield Laboratory of Ophthalmology), University of Oxford, Levels 5-6 West Wing, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK
| | - Sridhar R Vasudevan
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Kevin C Flanagan
- Department of Biological Sciences, University of Notre Dame, Galvin Life Sciences Center, Notre Dame, IN 46556, USA
| | - Daniel Anthony
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Grant C Churchill
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Matthew J A Wood
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
| | - Guido Steiner
- pRED Pharma Research and Development F. Hoffmann-La Roche, 4070 Basel, Switzerland
| | - Martin Ebeling
- pRED Pharma Research and Development F. Hoffmann-La Roche, 4070 Basel, Switzerland
| | - Markus Hossbach
- Axolabs GmbH Fritz-Hornschuch-Straße 9, 95326 Kulmbach, Germany
| | - Joseph G Wettstein
- pRED Pharma Research and Development F. Hoffmann-La Roche, 4070 Basel, Switzerland
| | - Giles E Duffield
- Department of Biological Sciences, University of Notre Dame, Galvin Life Sciences Center, Notre Dame, IN 46556, USA
| | - Silvia Gatti
- pRED Pharma Research and Development F. Hoffmann-La Roche, 4070 Basel, Switzerland
| | - Mark W Hankins
- Nuffield Department of Clinical Neurosciences (Nuffield Laboratory of Ophthalmology), University of Oxford, Levels 5-6 West Wing, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK
| | - Russell G Foster
- Nuffield Department of Clinical Neurosciences (Nuffield Laboratory of Ophthalmology), University of Oxford, Levels 5-6 West Wing, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK.
| | - Stuart N Peirson
- Nuffield Department of Clinical Neurosciences (Nuffield Laboratory of Ophthalmology), University of Oxford, Levels 5-6 West Wing, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK.
| |
Collapse
|
41
|
Flôres DEFL, Tomotani BM, Tachinardi P, Oda GA, Valentinuzzi VS. Modeling natural photic entrainment in a subterranean rodent (Ctenomys aff. knighti), the Tuco-Tuco. PLoS One 2013; 8:e68243. [PMID: 23874562 PMCID: PMC3707898 DOI: 10.1371/journal.pone.0068243] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 05/27/2013] [Indexed: 11/19/2022] Open
Abstract
Subterranean rodents spend most of the day inside underground tunnels, where there is little daily change in environmental variables. Our observations of tuco-tucos (Ctenomys aff. knighti) in a field enclosure indicated that these animals perceive the aboveground light-dark cycle by several bouts of light-exposure at irregular times during the light hours of the day. To assess whether such light-dark pattern acts as an entraining agent of the circadian clock, we first constructed in laboratory the Phase Response Curve for 1 h light-pulses (1000lux). Its shape is qualitatively similar to other curves reported in the literature and to our knowledge it is the first Phase Response Curve of a subterranean rodent. Computer simulations were performed with a non-linear limit-cycle oscillator subjected to a simple model of the light regimen experienced by tuco-tucos. Results showed that synchronization is achieved even by a simple regimen of a single daily light pulse scattered uniformly along the light hours of the day. Natural entrainment studies benefit from integrated laboratory, field and computational approaches.
Collapse
Affiliation(s)
- Danilo E. F. L. Flôres
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Barbara M. Tomotani
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Patricia Tachinardi
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Gisele A. Oda
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Veronica S. Valentinuzzi
- Centro Regional de Investigaciones Científicas y Transferencia Tecnológica-CRILAR, Entre Rios y Mendoza s/n, (5301) Anillaco, La Rioja, Argentina
| |
Collapse
|
42
|
Albert N, da Silva C, Díez-Noguera A, Cambras T. Different adaptation of the motor activity rhythm to chronic phase shifts between adolescent and adult rats. Behav Brain Res 2013; 252:347-55. [PMID: 23792134 DOI: 10.1016/j.bbr.2013.06.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 06/14/2013] [Accepted: 06/17/2013] [Indexed: 10/26/2022]
Abstract
Chronic phase shifts is a common feature in modern societies, which may induce sleep alterations and other health problems. The effects of phase shift on the circadian rhythms have been described to be more pronounced in old than in young animals. However, few works address the effects of chronic phase shifts during adolescence. Here we tested the development of the motor activity circadian rhythm of young rats under chronic phase shifts, which consisted on 6-h advances (A), 6h delays (D) or 6h advances and delays alternated every 5 days (AD) during the first 60 days after weaning. Moreover, the rhythmic pattern was compared to that of adult rats under the same lighting conditions. Results indicate that adolescent rats, independently on the lighting environment, developed a clear circadian rhythm, whose amplitude increased the first 50 days after weaning and showed a more stable circadian rhythm than adults under the same lighting conditions. In the case of A and AD groups, circadian disruption was observed only in adult rats. In all groups, the offset of activity correlated with light pattern better than the onset, and this correlation was always higher in the case of the rhythm of the pubertal rats. When AD groups were transferred to constant darkness, the group submitted to this condition during adolescence showed shorter period than that submitted in their adulthood. In conclusion, differently from adult rats, adolescent rats submitted to chronic phase shifts did not show circadian disruption and developed a single circadian rhythm, suggesting permanent changes in the circadian system.
Collapse
Affiliation(s)
- Nerea Albert
- Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain
| | | | | | | |
Collapse
|
43
|
Golombek DA, Casiraghi LP, Agostino PV, Paladino N, Duhart JM, Plano SA, Chiesa JJ. The times they're a-changing: effects of circadian desynchronization on physiology and disease. ACTA ACUST UNITED AC 2013; 107:310-22. [PMID: 23545147 DOI: 10.1016/j.jphysparis.2013.03.007] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Circadian rhythms are endogenous and need to be continuously entrained (synchronized) with the environment. Entrainment includes both coupling internal oscillators to external periodic changes as well as synchrony between the central clock and peripheral oscillators, which have been shown to exhibit different phases and resynchronization speed. Temporal desynchronization induces diverse physiological alterations that ultimately decrease quality of life and induces pathological situations. Indeed, there is a considerable amount of evidence regarding the deleterious effect of circadian dysfunction on overall health or on disease onset and progression, both in human studies and in animal models. In this review we discuss the general features of circadian entrainment and introduce diverse experimental models of desynchronization. In addition, we focus on metabolic, immune and cognitive alterations under situations of acute or chronic circadian desynchronization, as exemplified by jet-lag and shiftwork schedules. Moreover, such situations might lead to an enhanced susceptibility to diverse cancer types. Possible interventions (including light exposure, scheduled timing for meals and use of chronobiotics) are also discussed.
Collapse
Affiliation(s)
- Diego A Golombek
- Laboratory of Chronobiology, National University of Quilmes/CONICET, Buenos Aires, Argentina.
| | | | | | | | | | | | | |
Collapse
|
44
|
Mars 520-d mission simulation reveals protracted crew hypokinesis and alterations of sleep duration and timing. Proc Natl Acad Sci U S A 2013; 110:2635-40. [PMID: 23297197 DOI: 10.1073/pnas.1212646110] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The success of interplanetary human spaceflight will depend on many factors, including the behavioral activity levels, sleep, and circadian timing of crews exposed to prolonged microgravity and confinement. To address the effects of the latter, we used a high-fidelity ground simulation of a Mars mission to objectively track sleep-wake dynamics in a multinational crew of six during 520 d of confined isolation. Measurements included continuous recordings of wrist actigraphy and light exposure (4.396 million min) and weekly computer-based neurobehavioral assessments (n = 888) to identify changes in the crew's activity levels, sleep quantity and quality, sleep-wake periodicity, vigilance performance, and workload throughout the record-long 17 mo of mission confinement. Actigraphy revealed that crew sedentariness increased across the mission as evident in decreased waking movement (i.e., hypokinesis) and increased sleep and rest times. Light exposure decreased during the mission. The majority of crewmembers also experienced one or more disturbances of sleep quality, vigilance deficits, or altered sleep-wake periodicity and timing, suggesting inadequate circadian entrainment. The results point to the need to identify markers of differential vulnerability to hypokinesis and sleep-wake changes during the prolonged isolation of exploration spaceflight and the need to ensure maintenance of circadian entrainment, sleep quantity and quality, and optimal activity levels during exploration missions. Therefore, successful adaptation to such missions will require crew to transit in spacecraft and live in surface habitats that instantiate aspects of Earth's geophysical signals (appropriately timed light exposure, food intake, exercise) required for temporal organization and maintenance of human behavior.
Collapse
|
45
|
Granados-Fuentes D, Herzog ED. The clock shop: coupled circadian oscillators. Exp Neurol 2012; 243:21-7. [PMID: 23099412 DOI: 10.1016/j.expneurol.2012.10.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 09/04/2012] [Accepted: 10/16/2012] [Indexed: 01/10/2023]
Abstract
Daily rhythms in neural activity underlie circadian rhythms in sleep-wake and other daily behaviors. The cells within the mammalian suprachiasmatic nucleus (SCN) are intrinsically capable of 24-h timekeeping. These cells synchronize with each other and with local environmental cycles to drive coherent rhythms in daily behaviors. Recent studies have identified a small number of neuropeptides critical for this ability to synchronize and sustain coordinated daily rhythms. This review highlights the roles of specific intracellular and intercellular signals within the SCN that underlie circadian synchrony.
Collapse
|
46
|
Chong SYC, Ptáček LJ, Fu YH. Genetic insights on sleep schedules: this time, it's PERsonal. Trends Genet 2012; 28:598-605. [PMID: 22939700 DOI: 10.1016/j.tig.2012.08.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 07/17/2012] [Accepted: 08/06/2012] [Indexed: 12/12/2022]
Abstract
The study of circadian rhythms is emerging as a fruitful opportunity for understanding cellular mechanisms that govern human physiology and behavior, fueled by evidence directly linking sleep disorders to genetic mutations affecting circadian molecular pathways. Familial advanced sleep-phase disorder (FASPD) is the first recognized Mendelian circadian rhythm trait, and affected individuals exhibit exceptionally early sleep-wake onset due to altered post-translational regulation of period homolog 2 (PER2). Behavioral and cellular circadian rhythms are analogously affected because the circadian period length of behavior is reduced in the absence of environmental time cues, and cycle duration of the molecular clock is likewise shortened. In light of these findings, we review the PER2 dynamics in the context of circadian regulation to reveal the mechanism of sleep-schedule modulation. Understanding PER2 regulation and functionality may shed new light on how our genetic composition can influence our sleep-wake behaviors.
Collapse
Affiliation(s)
- S Y Christin Chong
- Department of Neurology, University of California San Francisco, San Francisco, CA 94158, USA
| | | | | |
Collapse
|
47
|
Prendergast BJ, Zucker I. Photoperiodic influences on ultradian rhythms of male Siberian hamsters. PLoS One 2012; 7:e41723. [PMID: 22848579 PMCID: PMC3407235 DOI: 10.1371/journal.pone.0041723] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 06/25/2012] [Indexed: 01/27/2023] Open
Abstract
Seasonal changes in mammalian physiology and behavior are proximately controlled by the annual variation in day length. Long summer and short winter day lengths markedly alter the amplitude of endogenous circadian rhythms and may affect ultradian oscillations, but the threshold photoperiods for inducing these changes are not known. We assessed the effects of short and intermediate day lengths and changes in reproductive physiology on circadian and ultradian rhythms of locomotor activity in Siberian hamsters. Males were maintained in a long photoperiod from birth (15 h light/day; 15 L) and transferred in adulthood to 1 of 7 experimental photoperiods ranging from 14 L to 9 L. Decreases in circadian rhythm (CR) robustness, mesor and amplitude were evident in photoperiods ≤14 L, as were delays in the timing of CR acrophase and expansion of nocturnal activity duration. Nocturnal ultradian rhythms (URs) were comparably prevalent in all day lengths, but 15 L markedly inhibited the expression of light-phase URs. The period (τ’), amplitude and complexity of URs increased in day lengths ≤13 L. Among hamsters that failed to undergo gonadal regression in short day lengths (nonresponders), τ’ of the dark-phase UR was longer than in photoresponsive hamsters; in 13 L the incidence and amplitude of light-phase URs were greater in hamsters that did not undergo testicular regression. Day lengths as long as 14 L were sufficient to trigger changes in the waveform of CRs without affecting UR waveform. The transition from a long- to a short-day ultradian phenotype occurred for most UR components at day lengths of 12 L–13 L, thereby establishing different thresholds for CR and UR responses to day length. At the UR-threshold photoperiod of 13 L, differences in gonadal status were largely without effect on most UR parameters.
Collapse
Affiliation(s)
- Brian J Prendergast
- Department of Psychology and Committee on Neurobiology, University of Chicago, Chicago, Illinois, United States of America.
| | | |
Collapse
|