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Domínguez-Valdés T, Bonnin-Arias C, Alvarez-Peregrina C, Galvez BG, Sanchez-Tena MA, Germain F, de la Villa P, Sánchez-Ramos C. Violet Light Effects on the Circadian Rest-Activity Rhythm and the Visual System. Clocks Sleep 2024; 6:433-445. [PMID: 39189196 PMCID: PMC11348119 DOI: 10.3390/clockssleep6030029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 08/05/2024] [Accepted: 08/06/2024] [Indexed: 08/28/2024] Open
Abstract
BACKGROUND Rooms illuminated by "black light" (<400 nm wavelength) has become popular, but there is not enough scientific evidence to support its implementation. This study aims to assess the effects of violet light (392 nm) on the circadian rest-activity rhythm and the visual system through animal experimentation. MATERIALS AND RESULTS Five groups of four mice were exposed to different white light, violet light, and dark periods, and their circadian rhythm was analyzed by measuring the circadian period using rest-activity cycles. Electroretinographic recordings and structural analysis of the retina were also performed on experimental animals. RESULTS Our study demonstrates that mice present normal circadian activity during exposure to violet light, taking rest not only under white light but under violet lighting periods. However, mice suffered a decrease in electrical retinal response after exposure to violet light as measured by electroretinography. Nevertheless, no structural changes were observed in the retinas of the animals under different lighting conditions. CONCLUSIONS Violet light elicits circadian rest-activity rhythm in mice but alters their visual function, although no structural changes are observed after short periods of violet light exposure.
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Affiliation(s)
- Teresa Domínguez-Valdés
- Faculty of Optics and Optometry, Universidad Complutense de Madrid, 28037 Madrid, Spain; (T.D.-V.); (C.B.-A.); (C.A.-P.); (C.S.-R.)
| | - Cristina Bonnin-Arias
- Faculty of Optics and Optometry, Universidad Complutense de Madrid, 28037 Madrid, Spain; (T.D.-V.); (C.B.-A.); (C.A.-P.); (C.S.-R.)
- Vision and Ophthalmology Research Group, Universidad Complutense de Madrid, 28037 Madrid, Spain
| | - Cristina Alvarez-Peregrina
- Faculty of Optics and Optometry, Universidad Complutense de Madrid, 28037 Madrid, Spain; (T.D.-V.); (C.B.-A.); (C.A.-P.); (C.S.-R.)
| | - Beatriz G. Galvez
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, Universidad Complutense de Madrid, 28040 Madrid, Spain;
| | - Miguel Angel Sanchez-Tena
- Faculty of Optics and Optometry, Universidad Complutense de Madrid, 28037 Madrid, Spain; (T.D.-V.); (C.B.-A.); (C.A.-P.); (C.S.-R.)
- ISEC LISBOA-Instituto Superior de Educação e Ciências, 1750-179 Lisbon, Portugal
| | - Francisco Germain
- Department of System Biology, University of Alcalá, 28805 Alcalá de Henares, Spain; (F.G.); (P.d.l.V.)
- Visual Neurophysiology Group, Instituto Ramon y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - Pedro de la Villa
- Department of System Biology, University of Alcalá, 28805 Alcalá de Henares, Spain; (F.G.); (P.d.l.V.)
- Visual Neurophysiology Group, Instituto Ramon y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - Celia Sánchez-Ramos
- Faculty of Optics and Optometry, Universidad Complutense de Madrid, 28037 Madrid, Spain; (T.D.-V.); (C.B.-A.); (C.A.-P.); (C.S.-R.)
- Vision and Ophthalmology Research Group, Universidad Complutense de Madrid, 28037 Madrid, Spain
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2
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Lloyd E, Rastogi A, Holtz N, Aaronson B, Craig Albertson R, Keene AC. Ontogeny and social context regulate the circadian activity patterns of Lake Malawi cichlids. J Comp Physiol B 2024; 194:299-313. [PMID: 37910192 PMCID: PMC11233325 DOI: 10.1007/s00360-023-01523-3] [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] [Received: 05/27/2023] [Revised: 09/01/2023] [Accepted: 09/25/2023] [Indexed: 11/03/2023]
Abstract
Activity patterns tend to be highly stereotyped and critical for executing many different behaviors including foraging, social interactions, and predator avoidance. Differences in the circadian timing of locomotor activity and rest periods can facilitate habitat partitioning and the exploitation of novel niches. As a consequence, closely related species often display highly divergent activity patterns, suggesting that shifts from diurnal to nocturnal behavior, or vice versa, are critical for survival. In Africa's Lake Malawi alone, there are over 500 species of cichlids, which inhabit diverse environments and exhibit extensive phenotypic variation. We have previously identified a substantial range in activity patterns across adult Lake Malawi cichlid species, from strongly diurnal to strongly nocturnal. In many species, including fishes, ecological pressures differ dramatically across life-history stages, raising the possibility that activity patterns may change over ontogeny. To determine if rest-activity patterns change across life stages, we compared the locomotor patterns of six Lake Malawi cichlid species. While total rest and activity did not change between early juvenile and adult stages, rest-activity patterns did, with juveniles displaying distinct activity rhythms that are more robust than adults. One distinct difference between juveniles and adults is the emergence of complex social behavior. To determine whether social context is required for activity rhythms, we next measured locomotor behavior in group-housed adult fish. We found that when normal social interactions were allowed, locomotor activity patterns were restored, supporting the notion that social interactions promote circadian regulation of activity in adult fish. These findings reveal a previously unidentified link between developmental stage and social interactions in the circadian timing of cichlid activity.
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Affiliation(s)
- Evan Lloyd
- Department of Biology, Texas A&M University, College Station, TX, 77840, USA
| | - Aakriti Rastogi
- Department of Biology, Texas A&M University, College Station, TX, 77840, USA
| | - Niah Holtz
- Organismic and Evolutionary Biology Graduate Program, University of Massachusetts, Amherst, MA, 01003, USA
| | - Ben Aaronson
- Department of Biology, University of Massachusetts, Amherst, MA, 01003, USA
| | - R Craig Albertson
- Department of Biology, University of Massachusetts, Amherst, MA, 01003, USA
| | - Alex C Keene
- Department of Biology, Texas A&M University, College Station, TX, 77840, USA.
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Dauchy RT, Hanifin JP, Brainard GC, Blask DE. Light: An Extrinsic Factor Influencing Animal-based Research. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE : JAALAS 2024; 63:116-147. [PMID: 38211974 PMCID: PMC11022951 DOI: 10.30802/aalas-jaalas-23-000089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 10/26/2023] [Accepted: 10/28/2023] [Indexed: 01/13/2024]
Abstract
Light is an environmental factor that is extrinsic to animals themselves and that exerts a profound influence on the regulation of circadian, neurohormonal, metabolic, and neurobehavioral systems of all animals, including research animals. These widespread biologic effects of light are mediated by distinct photoreceptors-rods and cones that comprise the conventional visual system and melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) of the nonvisual system that interact with the rods and cones. The rods and cones of the visual system, along with the ipRGCs of the nonvisual system, are species distinct in terms of opsins and opsin concentrations and interact with one another to provide vision and regulate circadian rhythms of neurohormonal and neurobehavioral responses to light. Here, we review a brief history of lighting technologies, the nature of light and circadian rhythms, our present understanding of mammalian photoreception, and current industry practices and standards. We also consider the implications of light for vivarium measurement, production, and technological application and provide simple recommendations on artificial lighting for use by regulatory authorities, lighting manufacturers, designers, engineers, researchers, and research animal care staff that ensure best practices for optimizing animal health and well-being and, ultimately, improving scientific outcomes.
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Key Words
- blad, blue-enriched led light at daytime
- clock, circadian locomotor output kaput
- cct, correlated color temperature
- cwf, cool white fluorescent
- ign, intergeniculate nucleus
- iprgc, intrinsically photosensitive retinal ganglion cell
- hiomt, hydroxyindole-o-methyltransferase
- k, kelvin temperature
- lan, light at night
- led, light-emitting diode
- lgn, lateral geniculate nucleus
- plr, pupillary light reflex
- pot, primary optic tract
- rht, retinohypothalamic tract
- scn, suprachiasmatic nuclei
- spd, spectral power distribution.
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Affiliation(s)
- Robert T Dauchy
- Department of Structural and Cellular Biology, Laboratory of Chrono-Neuroendocrine Oncology, Tulane University School of Medicine, New Orleans, Louisiana;,
| | - John P Hanifin
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - George C Brainard
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - David E Blask
- Department of Structural and Cellular Biology, Laboratory of Chrono-Neuroendocrine Oncology, Tulane University School of Medicine, New Orleans, Louisiana
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Lucas RJ, Allen AE, Brainard GC, Brown TM, Dauchy RT, Didikoglu A, Do MTH, Gaskill BN, Hattar S, Hawkins P, Hut RA, McDowell RJ, Nelson RJ, Prins JB, Schmidt TM, Takahashi JS, Verma V, Voikar V, Wells S, Peirson SN. Recommendations for measuring and standardizing light for laboratory mammals to improve welfare and reproducibility in animal research. PLoS Biol 2024; 22:e3002535. [PMID: 38470868 PMCID: PMC10931507 DOI: 10.1371/journal.pbio.3002535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024] Open
Abstract
Light enables vision and exerts widespread effects on physiology and behavior, including regulating circadian rhythms, sleep, hormone synthesis, affective state, and cognitive processes. Appropriate lighting in animal facilities may support welfare and ensure that animals enter experiments in an appropriate physiological and behavioral state. Furthermore, proper consideration of light during experimentation is important both when it is explicitly employed as an independent variable and as a general feature of the environment. This Consensus View discusses metrics to use for the quantification of light appropriate for nonhuman mammals and their application to improve animal welfare and the quality of animal research. It provides methods for measuring these metrics, practical guidance for their implementation in husbandry and experimentation, and quantitative guidance on appropriate light exposure for laboratory mammals. The guidance provided has the potential to improve data quality and contribute to reduction and refinement, helping to ensure more ethical animal use.
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Affiliation(s)
- Robert J. Lucas
- Centre for Biological Timing, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Annette E. Allen
- Centre for Biological Timing, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - George C. Brainard
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Timothy M. Brown
- Centre for Biological Timing, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Robert T. Dauchy
- Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane, Louisiana, United States of America
| | - Altug Didikoglu
- Department of Neuroscience, Izmir Institute of Technology, Gülbahçe, Urla, Izmir, Turkey
| | - Michael Tri H. Do
- F.M. Kirby Neurobiology Center and Department of Neurology, Boston Children’s Hospital and Harvard Medical School, Center for Life Science, Boston, Massachusetts, United States of America
| | - Brianna N. Gaskill
- Novartis Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
| | - Samer Hattar
- Section on Light and Circadian Rhythms (SLCR), National Institute of Mental Health, John Edward Porter Neuroscience Research Center, Bethesda, Maryland, United States of America
| | | | - Roelof A. Hut
- Chronobiology Unit, Groningen Institute of Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - Richard J. McDowell
- Centre for Biological Timing, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Randy J. Nelson
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, West Virginia, United States of America
| | - Jan-Bas Prins
- The Francis Crick Institute, London, United Kingdom
- Leiden University Medical Centre, Leiden, the Netherlands
| | - Tiffany M. Schmidt
- Department of Neurobiology, Northwestern University, Evanston, Illinois, United States of America
| | - Joseph S. Takahashi
- Department of Neuroscience, Peter O’Donnell Jr Brain Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Vandana Verma
- NASA Ames Research Center, Space Biosciences Division, Moffett Field, California, United States of America
| | - Vootele Voikar
- Laboratory Animal Center and Neuroscience Center, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Sara Wells
- The Mary Lyon Centre, MRC Harwell, Harwell Campus, Oxfordshire, United Kingdom
| | - Stuart N. Peirson
- Sleep and Circadian Neuroscience Institute (SCNi), Kavli Institute for Nanoscience Discovery, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
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Orlowska‐Feuer P, Bano‐Otalora B, Rodgers J, Martial FP, Storchi R, Lucas RJ. The mouse suprachiasmatic nucleus encodes irradiance via a diverse population of neurons monotonically tuned to different ranges of intensity. J Physiol 2023; 601:4737-4749. [PMID: 37777993 PMCID: PMC10953322 DOI: 10.1113/jp285000] [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] [Received: 05/18/2023] [Accepted: 09/11/2023] [Indexed: 10/03/2023] Open
Abstract
Many neurons of the mammalian master circadian oscillator in the suprachiasmatic nuclei (SCN) respond to light pulses with irradiance-dependent changes in firing. Here, we set out to better understand this irradiance coding ability by considering how the SCN tracks more continuous changes in irradiance at both population and single unit level. To this end, we recorded extracellular activity in the SCN of anaesthetised mice presented with up + down irradiance staircase stimuli covering moonlight to daylight conditions and incorporating epochs with steady light or superimposed higher frequency modulations (temporal white noise (WN) and frequency/contrast chirps). Single unit activity was extracted by spike sorting. The population response of SCN units to this stimulus was a progressive increase in firing rate at higher irradiances. This relationship was symmetrical for up vs. down phases of the ramp in the presence of white noise or chirps but exhibited hysteresis for steady light, with firing systematically higher during increasing irradiance. Single units also showed a monotonic relationship between firing and irradiance but exhibited diversity not only in response polarity (increases vs. decreases in firing), but also in the sensitivity (EC50 ) and slope of fitted functions. These data show that individual SCN neurons exhibit monotonic relationships between irradiance and firing rate but differ in the irradiance range over which they respond. This property may help the SCN to encode the large differences in irradiance found in nature using neurons with a constrained range of firing rates. KEY POINTS: Daily changes in environmental light (irradiance) entrain the suprachiasmatic nucleus (SCN) circadian clock. The mouse SCN shows graded increases in neurophysiological activity with light pulses of increasing irradiance. We show that this monotonic relationship between firing rate and irradiance is retained at population and single unit level when probed with more naturalistic staircase increases and decreases in irradiance. The irradiance response is more reliable in the presence of ongoing higher temporal frequency modulations in light intensity than under steady light. Single units varied in sensitivity allowing the population to cover a wide range of irradiances. Irradiance coding in the SCN has characteristics of a sparse code with individual neurons tracking different portions of the natural irradiance range. This property may address the challenge of encoding a 109 -fold day:night difference in irradiance within the constrained range of firing rates available to individual neurons.
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Affiliation(s)
- Patrycja Orlowska‐Feuer
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterOxford RoadManchesterUK
| | - Beatriz Bano‐Otalora
- Centre for Biological Timing, Faculty of Biology, Medicine and HealthUniversity of ManchesterOxford RoadManchesterUK
| | - Jessica Rodgers
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterOxford RoadManchesterUK
| | - Franck P. Martial
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterOxford RoadManchesterUK
| | - Riccardo Storchi
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterOxford RoadManchesterUK
| | - Robert James Lucas
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterOxford RoadManchesterUK
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6
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Pan D, Wang Z, Chen Y, Cao J. Melanopsin-mediated optical entrainment regulates circadian rhythms in vertebrates. Commun Biol 2023; 6:1054. [PMID: 37853054 PMCID: PMC10584931 DOI: 10.1038/s42003-023-05432-7] [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] [Received: 07/08/2023] [Accepted: 10/09/2023] [Indexed: 10/20/2023] Open
Abstract
Melanopsin (OPN4) is a light-sensitive protein that plays a vital role in the regulation of circadian rhythms and other nonvisual functions. Current research on OPN4 has focused on mammals; more evidence is needed from non-mammalian vertebrates to fully assess the significance of the non-visual photosensitization of OPN4 for circadian rhythm regulation. There are species differences in the regulatory mechanisms of OPN4 for vertebrate circadian rhythms, which may be due to the differences in the cutting variants, tissue localization, and photosensitive activation pathway of OPN4. We here summarize the distribution of OPN4 in mammals, birds, and teleost fish, and the classical excitation mode for the non-visual photosensitive function of OPN4 in mammals is discussed. In addition, the role of OPN4-expressing cells in regulating circadian rhythm in different vertebrates is highlighted, and the potential rhythmic regulatory effects of various neuropeptides or neurotransmitters expressed in mammalian OPN4-expressing ganglion cells are summarized among them.
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Affiliation(s)
- Deng Pan
- Laboratory of Anatomy of Domestic Animals, National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Haidian, 100193, Beijing, China
| | - Zixu Wang
- Laboratory of Anatomy of Domestic Animals, National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Haidian, 100193, Beijing, China
| | - Yaoxing Chen
- Laboratory of Anatomy of Domestic Animals, National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Haidian, 100193, Beijing, China
| | - Jing Cao
- Laboratory of Anatomy of Domestic Animals, National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Haidian, 100193, Beijing, China.
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7
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Campbell I, Sharifpour R, Vandewalle G. Light as a Modulator of Non-Image-Forming Brain Functions—Positive and Negative Impacts of Increasing Light Availability. Clocks Sleep 2023; 5:116-140. [PMID: 36975552 PMCID: PMC10047820 DOI: 10.3390/clockssleep5010012] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 02/17/2023] [Accepted: 03/13/2023] [Indexed: 03/19/2023] Open
Abstract
Light use is rising steeply, mainly because of the advent of light-emitting diode (LED) devices. LEDs are frequently blue-enriched light sources and may have different impacts on the non-image forming (NIF) system, which is maximally sensitive to blue-wavelength light. Most importantly, the timing of LED device use is widespread, leading to novel light exposure patterns on the NIF system. The goal of this narrative review is to discuss the multiple aspects that we think should be accounted for when attempting to predict how this situation will affect the NIF impact of light on brain functions. We first cover both the image-forming and NIF pathways of the brain. We then detail our current understanding of the impact of light on human cognition, sleep, alertness, and mood. Finally, we discuss questions concerning the adoption of LED lighting and screens, which offer new opportunities to improve well-being, but also raise concerns about increasing light exposure, which may be detrimental to health, particularly in the evening.
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8
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Dauchy RT, Blask DE. Vivarium Lighting as an Important Extrinsic Factor Influencing Animal-based Research. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE : JAALAS 2023; 62:3-25. [PMID: 36755210 PMCID: PMC9936857 DOI: 10.30802/aalas-jaalas-23-000003] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/26/2022] [Accepted: 09/02/2022] [Indexed: 01/22/2023]
Abstract
Light is an extrinsic factor that exerts widespread influence on the regulation of circadian, physiologic, hormonal, metabolic, and behavioral systems of all animals, including those used in research. These wide-ranging biologic effects of light are mediated by distinct photoreceptors, the melanopsin-containing intrinsically photosensitive retinal ganglion cells of the nonvisual system, which interact with the rods and cones of the conventional visual system. Here, we review the nature of light and circadian rhythms, current industry practices and standards, and our present understanding of the neurophysiology of the visual and nonvisual systems. We also consider the implications of this extrinsic factor for vivarium measurement, production, and technological application of light, and provide simple recommendations on artificial lighting for use by regulatory authorities, lighting manufacturers, designers, engineers, researchers, and research animal care staff that ensure best practices for optimizing animal health and wellbeing and, ultimately, improving scientific outcomes.
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Key Words
- blad, blue-enriched led light at daytime
- clock, circadian locomotor output kaput
- cct, correlated color temperature
- cwf, cool white fluorescent
- iprgc, intrinsically photosensitive retinal ganglion cell
- hiomt, hydroxyindole-o-methyltransferase
- lan, light at night
- led, light-emitting diode
- plr, pupillary light reflex
- scn, suprachiasmatic nuclei
- spd, spectral power distribution
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Affiliation(s)
- Robert T Dauchy
- Department of Structural and Cellular Biology, Laboratory of Chrono-Neuroendocrine Oncology, Tulane University School of Medicine, New Orleans, Louisiana
| | - David E Blask
- Department of Structural and Cellular Biology, Laboratory of Chrono-Neuroendocrine Oncology, Tulane University School of Medicine, New Orleans, Louisiana
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9
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Nakaya M, Wakamatsu M, Motegi H, Tanaka A, Sutherland K, Ishikawa M, Ozaki M, Shirato H, Hamada K, Hamada T. A real-time measurement system for gene expression rhythms from deep tissues of freely moving mice under light-dark conditions. Biochem Biophys Rep 2022; 32:101344. [PMID: 36160030 PMCID: PMC9489493 DOI: 10.1016/j.bbrep.2022.101344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 09/05/2022] [Accepted: 09/06/2022] [Indexed: 10/24/2022] Open
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10
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Divergent outer retinal circuits drive image and non-image visual behaviors. Cell Rep 2022; 39:111003. [PMID: 35767957 PMCID: PMC9400924 DOI: 10.1016/j.celrep.2022.111003] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/25/2022] [Accepted: 06/03/2022] [Indexed: 11/22/2022] Open
Abstract
Image- and non-image-forming vision are essential for animal behavior. Here we use genetically modified mouse lines to examine retinal circuits driving image- and non-image-functions. We describe the outer retinal circuits underlying the pupillary light response (PLR) and circadian photoentrainment, two non-image-forming behaviors. Rods and cones signal light increments and decrements through the ON and OFF pathways, respectively. We find that the OFF pathway drives image-forming vision but cannot drive circadian photoentrainment or the PLR. Cone light responses drive image formation but fail to drive the PLR. At photopic levels, rods use the primary and secondary rod pathways to drive the PLR, whereas at the scotopic and mesopic levels, rods use the primary pathway to drive the PLR, and the secondary pathway is insufficient. Circuit dynamics allow rod ON pathways to drive two non-image-forming behaviors across a wide range of light intensities, whereas the OFF pathway is potentially restricted to image formation.
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11
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Schoonderwoerd RA, Buck TM, Andriessen CA, Wijnholds J, Hattar S, Meijer JH, Deboer T. Sleep Deprivation Does not Change the Flash Electroretinogram in Wild-type and Opn4-/-Gnat1-/- Mice. J Biol Rhythms 2022; 37:216-221. [PMID: 35132885 PMCID: PMC9008555 DOI: 10.1177/07487304221074995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Sleep deprivation reduces the response of neuronal activity in the suprachiasmatic nucleus (SCN) and the phase shift in circadian behaviour to phase shifting light pulses, and thus seems to impair the adaptation of the circadian clock to the external light-dark cycle. The question remains where in the pathway of light input to the SCN the response is reduced. We therefore investigated whether the electroretinogram (ERG) changes after sleep deprivation in wild-type mice and in Opn4−/−Gnat1−/− mutant male mice. We found that the ERG is clearly affected by the Opn4−/−Gnat1−/− mutations, but that the ERG after sleep deprivation does not differ from the baseline response. The difference between wild-type and mutant is in accordance with the lack of functional rod and melanopsin in the retina of the mutant mice. We conclude that the decrease in light responsiveness of the SCN after sleep deprivation is probably not caused by changes at the retinal level, but rather at the postsynaptic site within the SCN, reflecting affected neurotransmitter signalling.
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Affiliation(s)
- Robin A Schoonderwoerd
- Laboratory for Neurophysiology, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Thilo M Buck
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | | | - Jan Wijnholds
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - Samer Hattar
- Section of Light and Circadian Rhythms, National Institutes of Health, Bethesda, Maryland, USA
| | - Johanna H Meijer
- Laboratory for Neurophysiology, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Tom Deboer
- Laboratory for Neurophysiology, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
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12
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Steel LCE, Tir S, Tam SKE, Bussell JN, Spitschan M, Foster RG, Peirson SN. Effects of Cage Position and Light Transmission on Home Cage Activity and Circadian Entrainment in Mice. Front Neurosci 2022; 15:832535. [PMID: 35082600 PMCID: PMC8784806 DOI: 10.3389/fnins.2021.832535] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 12/15/2021] [Indexed: 11/13/2022] Open
Abstract
Light is known to exert powerful effects on behavior and physiology, including upon the amount and distribution of activity across the day/night cycle. Here we use home cage activity monitoring to measure the effect of differences in home cage light spectrum and intensity on key circadian activity parameters in mice. Due to the relative positioning of any individually ventilated cage (IVC) with regard to the animal facility lighting, notable differences in light intensity occur across the IVC rack. Although all mice were found to be entrained, significant differences in the timing of activity onset and differences in activity levels were found between mice housed in standard versus red filtering cages. Furthermore, by calculating the effective irradiance based upon the known mouse photopigments, a significant relationship between light intensity and key circadian parameters are shown. Perhaps unsurprisingly given the important role of the circadian photopigment melanopsin in circadian entrainment, melanopic illuminance is shown to correlate more strongly with key circadian activity parameters than photopic lux. Collectively, our results suggest that differences in light intensity may reflect an uncharacterized source of variation in laboratory rodent research, with potential consequences for reproducibility. Room design and layout vary within and between facilities, and caging design and lighting location relative to cage position can be highly variable. We suggest that cage position should be factored into experimental design, and wherever possible, experimental lighting conditions should be characterized as a way of accounting for this source of variation.
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Affiliation(s)
- Laura C. E. Steel
- Nuffield Department of Clinical Neurosciences, Sir Jules Thorn Sleep and Circadian Neuroscience Institute (SCNi), University of Oxford, Oxford, United Kingdom
| | - Selma Tir
- Nuffield Department of Clinical Neurosciences, Sir Jules Thorn Sleep and Circadian Neuroscience Institute (SCNi), University of Oxford, Oxford, United Kingdom
| | - Shu K. E. Tam
- Nuffield Department of Clinical Neurosciences, Sir Jules Thorn Sleep and Circadian Neuroscience Institute (SCNi), University of Oxford, Oxford, United Kingdom
| | - James N. Bussell
- Department of Biomedical Services, University of Oxford, Oxford, United Kingdom
| | - Manuel Spitschan
- Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- TUM Department of Sport and Health Sciences (TUM SG), Technical University of Munich, Munich, Germany
| | - Russell G. Foster
- Nuffield Department of Clinical Neurosciences, Sir Jules Thorn Sleep and Circadian Neuroscience Institute (SCNi), University of Oxford, Oxford, United Kingdom
| | - Stuart N. Peirson
- Nuffield Department of Clinical Neurosciences, Sir Jules Thorn Sleep and Circadian Neuroscience Institute (SCNi), University of Oxford, Oxford, United Kingdom
- *Correspondence: Stuart N. Peirson,
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13
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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.
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14
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Beyond irradiance: Visual signals influencing mammalian circadian function. PROGRESS IN BRAIN RESEARCH 2022; 273:145-169. [DOI: 10.1016/bs.pbr.2022.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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Jeczmien-Lazur JS, Orlowska-Feuer P, Kustron A, Lewandowski MH. Short Wavelengths Contribution to Light-induced Responses and Irradiance Coding in the Rat Dorsal Lateral Geniculate Nucleus - An In vivo Electrophysiological Approach. Neuroscience 2021; 468:220-234. [PMID: 34146632 DOI: 10.1016/j.neuroscience.2021.06.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 06/07/2021] [Accepted: 06/10/2021] [Indexed: 10/21/2022]
Abstract
The dorsal lateral geniculate nucleus (dLGN) is the main neuronal station en route to higher visual areas. It receives information about environmental light from retinal photoreceptors whose sensitivity peaks are distributed across a visible spectrum. Here, using electrophysiological multichannel recordings in vivo combined with different light stimulations, we investigated short wavelength contribution to the dLGN responses to light and irradiance coding. The results showed that the majority of dLGN cells responded evenly to almost all wavelengths from the 340 to 490 nm spectrum; however, some cells representing extremes of unimodal distribution of Blue-UV index were specialised in the reception of blue or UV light. Moreover, by using alternate yellow and monochromatic light stimuli from blue - UV range, we also assessed the relative spectral contribution to rat dLGN responses to light. Finally, we observed no clear changes in the irradiance coding property of short wavelength-deficient light stimuli, however we noticed a distortion of the coding curves manifested by a significant drop in measure of fit after using short wavelength blocking filter. In conclusion, our data provide the first electrophysiological report on dLGN short wavelength-induced responses under changing light conditions and suggest the presence of colour opponent cells in the rat dLGN.
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Affiliation(s)
- Jagoda Stanislawa Jeczmien-Lazur
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland; Malopolska Centre of Biotechnology (MCB), Jagiellonian University in Krakow, Krakow, Poland
| | - Patrycja Orlowska-Feuer
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland; Malopolska Centre of Biotechnology (MCB), Jagiellonian University in Krakow, Krakow, Poland.
| | - Anna Kustron
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland
| | - Marian Henryk Lewandowski
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland.
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16
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Distinct contribution of cone photoreceptor subtypes to the mammalian biological clock. Proc Natl Acad Sci U S A 2021; 118:2024500118. [PMID: 34050024 PMCID: PMC8179201 DOI: 10.1073/pnas.2024500118] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Synchronization of our biological clocks to the environmental day–night cycle critically depends on daily exposure to light. Here, we show that cones transmit distinct photic information to the clock by performing recordings of clock neurons in freely moving mice with cones as their only photoreceptors. This is in contrast to the expectation that exclusively melanopsin and rods fulfil this role. Moreover, we show that especially short-wavelength–sensitive cones as compared to mid-wavelength–sensitive cones are important. The evidence for a role for cones implicates that clocks respond to a broad spectrum of colors rather than to blue light, which can be used to strengthen the clock in humans. Ambient light detection is important for the synchronization of the circadian clock to the external solar cycle. Light signals are sent to the suprachiasmatic nuclei (SCN), the site of the major circadian pacemaker. It has been assumed that cone photoreceptors contribute minimally to synchronization. Here, however, we find that cone photoreceptors are sufficient for mediating entrainment and transmitting photic information to the SCN, as evaluated in mice that have only cones as functional photoreceptors. Using in vivo electrophysiological recordings in the SCN of freely moving cone-only mice, we observed light responses in SCN neuronal activity in response to 60-s pulses of both ultraviolet (UV) (λmax 365 nm) and green (λmax 505 nm) light. Higher irradiances of UV light led to irradiance-dependent enhancements in SCN neuronal activity, whereas higher irradiances of green light led to a reduction in the sustained response with only the transient response remaining. Responses in SCN neuronal activity decayed with a half-max time of ∼9 min for UV light and less than a minute for green light, indicating differential input between short-wavelength–sensitive and mid-wavelength–sensitive cones for the SCN responsiveness. Furthermore, we show that UV light is more effective for photoentrainment than green light. Based on the lack of a full sustained response in cone-only mice, we confirmed that rapidly alternating light levels, rather than slowly alternating light, caused substantial phase shifts. Together, our data provide strong evidence that cone types contribute to photoentrainment and differentially affect the electrical activity levels of the SCN.
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17
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Wong KY, Fernandez FX. Circadian Responses to Light-Flash Exposure: Conceptualization and New Data Guiding Future Directions. Front Neurol 2021; 12:627550. [PMID: 33643205 PMCID: PMC7905211 DOI: 10.3389/fneur.2021.627550] [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: 11/09/2020] [Accepted: 01/21/2021] [Indexed: 01/03/2023] Open
Abstract
A growing number of studies document circadian phase-shifting after exposure to millisecond light flashes. When strung together by intervening periods of darkness, these stimuli evoke pacemaker responses rivaling or outmatching those created by steady luminance, suggesting that the circadian system's relationship to light can be contextualized outside the principle of simple dose-dependence. In the current review, we present a brief chronology of this work. We then develop a conceptual model around it that attempts to relate the circadian effects of flashes to a natural integrative process the pacemaker uses to intermittently sample the photic information available at dawn and dusk. Presumably, these snapshots are employed as building blocks in the construction of a coherent representation of twilight the pacemaker consults to orient the next day's physiology (in that way, flash-resetting of pacemaker rhythms might be less an example of a circadian visual illusion and more an example of the kinds of gestalt inferences that the image-forming system routinely makes when identifying objects within the visual field; i.e., closure). We conclude our review with a discussion on the role of cones in the pacemaker's twilight predictions, providing new electrophysiological data suggesting that classical photoreceptors—but not melanopsin—are necessary for millisecond, intermediate-intensity flash responses in ipRGCs (intrinsically photosensitive retinal ganglion cells). Future investigations are necessary to confirm this “Cone Sentinel Model” of circadian flash-integration and twilight-prediction, and to further define the contribution of cones vs. rods in transducing pacemaker flash signals.
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Affiliation(s)
- Kwoon Y Wong
- Department of Molecular, Cellular, & Developmental Biology, University of Michigan, Ann Arbor, MI, United States.,Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Fabian-Xosé Fernandez
- Department of Psychology, BIO5 Research Institute, University of Arizona, Tucson, AZ, United States.,Department of Neurology, McKnight Brain Research Institute, University of Arizona, Tucson, AZ, United States
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18
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Lee R, Tapia A, Kaladchibachi S, Grandner MA, Fernandez FX. Meta-analysis of light and circadian timekeeping in rodents. Neurosci Biobehav Rev 2021; 123:215-229. [PMID: 33513413 DOI: 10.1016/j.neubiorev.2020.12.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 12/12/2020] [Accepted: 12/17/2020] [Indexed: 12/19/2022]
Abstract
We conducted a meta-analysis of papers published over the past half-century (1964-2017) that quantified the phase-shifting effects of timed light exposure on rodent locomotor rhythms. Descriptive statistics were tabulated in order to explore the extent to which these studies were generalizable across species, sex, age, circadian timing, and light sources. Attempts at understanding photic resetting were primarily targeted at younger male animals, with particular emphases placed on characterizing the pacemaker systems of C57BL/6 mice and Syrian hamsters during the parts of their subjective night most sensitive to delivery of white-fluorescent light. With subsequent analyses restricted to these rodent models, we then assessed the relationship between luminous exposure (via broadspectrum emission) and phase-shifting through a series of linear regressions. Monotonically increasing illuminance-response functions were noted at most circadian times surveyed. In the aggregate, our results show that previous research conducted on light's regulation of circadian timekeeping has been skewed in design with respect to several important biological variables. This bias might limit translation of phototherapy-relevant data to women and older individuals.
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Affiliation(s)
- Robert Lee
- Department of Psychology, University of Arizona, Tucson, AZ, USA
| | - Amaris Tapia
- Department of Psychology, University of Arizona, Tucson, AZ, USA
| | | | - Michael A Grandner
- Sleep and Health Research Program, Department of Psychiatry, University of Arizona, Tucson, AZ, USA
| | - Fabian-Xosé Fernandez
- Department of Psychology, University of Arizona, Tucson, AZ, USA; Department of Neurology, University of Arizona, Tucson, AZ, USA; BIO5 and McKnight Brain Research Institutes, Tucson, AZ, USA.
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19
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Orlowska-Feuer P, Smyk MK, Alwani A, Lewandowski MH. Neuronal Responses to Short Wavelength Light Deficiency in the Rat Subcortical Visual System. Front Neurosci 2021; 14:615181. [PMID: 33488355 PMCID: PMC7815651 DOI: 10.3389/fnins.2020.615181] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 12/08/2020] [Indexed: 12/26/2022] Open
Abstract
The amount and spectral composition of light changes considerably during the day, with dawn and dusk being the most crucial moments when light is within the mesopic range and short wavelength enriched. It was recently shown that animals use both cues to adjust their internal circadian clock, thereby their behavior and physiology, with the solar cycle. The role of blue light in circadian processes and neuronal responses is well established, however, an unanswered question remains: how do changes in the spectral composition of light (short wavelengths blocking) influence neuronal activity? In this study we addressed this question by performing electrophysiological recordings in image (dorsal lateral geniculate nucleus; dLGN) and non-image (the olivary pretectal nucleus; OPN, the suprachiasmatic nucleus; SCN) visual structures to determine neuronal responses to spectrally varied light stimuli. We found that removing short-wavelength from the polychromatic light (cut off at 525 nm) attenuates the most transient ON and sustained cells in the dLGN and OPN, respectively. Moreover, we compared the ability of different types of sustained OPN neurons (either changing or not their response profile to filtered polychromatic light) to irradiance coding, and show that both groups achieve it with equal efficacy. On the other hand, even very dim monochromatic UV light (360 nm; log 9.95 photons/cm2/s) evokes neuronal responses in the dLGN and SCN. To our knowledge, this is the first electrophysiological experiment supporting previous behavioral findings showing visual and circadian functions disruptions under short wavelength blocking environment. The current results confirm that neuronal activity in response to polychromatic light in retinorecipient structures is affected by removing short wavelengths, however, with type and structure – specific action. Moreover, they show that rats are sensitive to even very dim UV light.
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Affiliation(s)
- Patrycja Orlowska-Feuer
- Malopolska Centre of Biotechnology (MCB), Jagiellonian University in Kraków, Kraków, Poland.,Department of Neurophysiology and Chronobiology, Jagiellonian University in Kraków, Kraków, Poland
| | - Magdalena Kinga Smyk
- Malopolska Centre of Biotechnology (MCB), Jagiellonian University in Kraków, Kraków, Poland.,Department of Neurophysiology and Chronobiology, Jagiellonian University in Kraków, Kraków, Poland
| | - Anna Alwani
- Department of Neurophysiology and Chronobiology, Jagiellonian University in Kraków, Kraków, Poland
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20
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Michel S, Nakamura TJ, Meijer JH, Colwell CS. Electrophysiological Approaches to Studying the Suprachiasmatic Nucleus. Methods Mol Biol 2021; 2130:303-324. [PMID: 33284454 DOI: 10.1007/978-1-0716-0381-9_23] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In mammals, the part of the nervous system responsible for most circadian behavior can be localized to a bilaterally paired structure in the hypothalamus known as the suprachiasmatic nucleus (SCN). Understanding the mammalian circadian system will require a detailed multilevel analysis of neural SCN circuits ex vivo and in vivo. Many of the techniques and approaches that are used for the analysis of the circuitry driving circadian oscillations in the SCN are similar to those employed in other brain regions. There is, however, one fundamental difference that needs to be taken into consideration, that is, the physiological, cell, and molecular properties of SCN neurons vary with the time of day. In this chapter, we will consider the preparations and electrophysiological techniques that we have used to analyze the SCN circuit focusing on the acute brain slice and intact, freely moving animal.
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Affiliation(s)
- Stephan Michel
- Laboratory for Neurophysiology, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands.
| | - Takahiro J Nakamura
- Laboratory of Animal Physiology, Department of Life Sciences, School of Agriculture, Meiji University, Tama-ku Kawasaki, Kanagawa, Japan
| | - Johanna H Meijer
- Laboratory for Neurophysiology, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Christopher S Colwell
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, CA, USA
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21
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Harding C, Bechtold DA, Brown TM. Suprachiasmatic nucleus-dependent and independent outputs driving rhythmic activity in hypothalamic and thalamic neurons. BMC Biol 2020; 18:134. [PMID: 32998726 PMCID: PMC7528611 DOI: 10.1186/s12915-020-00871-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 09/17/2020] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Daily variations in mammalian physiology are under control of a central clock in the suprachiasmatic nucleus (SCN). SCN timing signals are essential for coordinating cellular clocks and associated circadian variations in cell and tissue function across the body; however, direct SCN projections primarily target a restricted set of hypothalamic and thalamic nuclei involved in physiological and behavioural control. The role of the SCN in driving rhythmic activity in these targets remains largely unclear. Here, we address this issue via multielectrode recording and manipulations of SCN output in adult mouse brain slices. RESULTS Electrical stimulation identifies cells across the midline hypothalamus and ventral thalamus that receive inhibitory input from the SCN and/or excitatory input from the retina. Optogenetic manipulations confirm that SCN outputs arise from both VIP and, more frequently, non-VIP expressing cells and that both SCN and retinal projections almost exclusively target GABAergic downstream neurons. The majority of midline hypothalamic and ventral thalamic neurons exhibit circadian variation in firing and those receiving inhibitory SCN projections consistently exhibit peak activity during epochs when SCN output is low. Physical removal of the SCN confirms that neuronal rhythms in ~ 20% of the recorded neurons rely on central clock input but also reveals many neurons that can express circadian variation in firing independent of any SCN input. CONCLUSIONS We identify cell populations across the midline hypothalamus and ventral thalamus exhibiting SCN-dependent and independent rhythms in neural activity, providing new insight into the mechanisms by which the circadian system generates daily physiological rhythms.
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Affiliation(s)
- Court Harding
- Centre for Biological Timing, Faculty of Medicine, Biology and Health, University of Manchester, Manchester, UK
| | - David A Bechtold
- Centre for Biological Timing, Faculty of Medicine, Biology and Health, University of Manchester, Manchester, UK
| | - Timothy M Brown
- Centre for Biological Timing, Faculty of Medicine, Biology and Health, University of Manchester, Manchester, UK.
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22
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Foster RG, Hughes S, Peirson SN. Circadian Photoentrainment in Mice and Humans. BIOLOGY 2020; 9:biology9070180. [PMID: 32708259 PMCID: PMC7408241 DOI: 10.3390/biology9070180] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 07/03/2020] [Accepted: 07/05/2020] [Indexed: 12/26/2022]
Abstract
Light around twilight provides the primary entrainment signal for circadian rhythms. Here we review the mechanisms and responses of the mouse and human circadian systems to light. Both utilize a network of photosensitive retinal ganglion cells (pRGCs) expressing the photopigment melanopsin (OPN4). In both species action spectra and functional expression of OPN4 in vitro show that melanopsin has a λmax close to 480 nm. Anatomical findings demonstrate that there are multiple pRGC sub-types, with some evidence in mice, but little in humans, regarding their roles in regulating physiology and behavior. Studies in mice, non-human primates and humans, show that rods and cones project to and can modulate the light responses of pRGCs. Such an integration of signals enables the rods to detect dim light, the cones to detect higher light intensities and the integration of intermittent light exposure, whilst melanopsin measures bright light over extended periods of time. Although photoreceptor mechanisms are similar, sensitivity thresholds differ markedly between mice and humans. Mice can entrain to light at approximately 1 lux for a few minutes, whilst humans require light at high irradiance (>100’s lux) and of a long duration (>30 min). The basis for this difference remains unclear. As our retinal light exposure is highly dynamic, and because photoreceptor interactions are complex and difficult to model, attempts to develop evidence-based lighting to enhance human circadian entrainment are very challenging. A way forward will be to define human circadian responses to artificial and natural light in the “real world” where light intensity, duration, spectral quality, time of day, light history and age can each be assessed.
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23
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Hanifin JP, Dauchy RT, Blask DE, Hill SM, Brainard GC. Relevance of Electrical Light on Circadian, Neuroendocrine, and Neurobehavioral Regulation in Laboratory Animal Facilities. ILAR J 2020; 60:150-158. [PMID: 33094817 DOI: 10.1093/ilar/ilaa010] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 03/25/2020] [Accepted: 04/15/2020] [Indexed: 02/03/2023] Open
Abstract
Light is a key extrinsic factor to be considered in operations and design of animal room facilities. Over the past four decades, many studies on typical laboratory animal populations have demonstrated impacts on neuroendocrine, neurobehavioral, and circadian physiology. These effects are regulated independently from the defined physiology for the visual system. The range of physiological responses that oscillate with the 24 hour rhythm of the day include sleep and wakefulness, body temperature, hormonal secretion, and a wide range of other physiological parameters. Melatonin has been the chief neuroendocrine hormone studied, but acute light-induced effects on corticosterone as well as other hormones have also been observed. Within the last two decades, a new photosensory system in the mammalian eye has been discovered. A small set of retinal ganglion cells, previously thought to function as a visual output neuron, have been shown to be directly photosensitive and act differently from the classic photoreceptors of the visual system. Understanding the effects of light on mammalian physiology and behavior must take into account how the classical visual photoreceptors and the newly discovered ipRGC photoreceptor systems interact. Scientists and facility managers need to appreciate lighting impacts on circadian, neuroendocrine, and neurobehavioral regulation in order to improve lighting of laboratory facilities to foster optimum health and well-being of animals.
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Affiliation(s)
- John P Hanifin
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Robert T Dauchy
- Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane, Louisiana
| | - David E Blask
- Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane, Louisiana
| | - Steven M Hill
- Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane, Louisiana
| | - George C Brainard
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania
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24
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Abstract
At the core of human thought, for the majority of individuals in the developed nations at least, there is the tacit assumption that as a species we are unfettered by the demands imposed by our biology and that we can do what we want, at whatever time we choose, whereas in reality every aspect of our physiology and behaviour is constrained by a 24 h beat arising from deep within our evolution. Our daily circadian rhythms and sleep/wake cycle allow us to function optimally in a dynamic world, adjusting our biology to the demands imposed by the day/night cycle. The themes developed in this review focus upon the growing realization that we ignore the circadian and sleep systems at our peril, and this paper considers the mechanisms that generate and regulate circadian and sleep systems; what happens mechanistically when these systems collapse as a result of societal pressures and disease; how sleep disruption and stress are linked; why sleep disruption and mental illness invariably occur together; and how individuals and employers can attempt to mitigate some of the problems associated with working against our internal temporal biology. While some of the health costs of sleep disruption can be reduced, in the short-term at least, there will always be significant negative consequences associated with shift work and sleep loss. With this in mind, society needs to address this issue and decide when the consequences of sleep disruption are justified in the workplace.
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Affiliation(s)
- Russell G. Foster
- Sleep and Circadian Neuroscience Institute (SCNi) and Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, OMPI, Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
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25
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Abstract
Sleep is a universal phenomenon occurring in all species studied thus far. Sleep loss results in adverse physiological effects at both the organismal and cellular levels suggesting an adaptive role for sleep in the maintenance of overall health. This review examines the bidirectional relationship between sleep and cellular stress. Cellular stress in this review refers to a shift in cellular homeostasis in response to an external stressor. Studies that illustrate the fact that sleep loss induces cellular stress and those that provide evidence that cellular stress in turn promotes sleep will be discussed.
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Affiliation(s)
- Julie A Williams
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
- Chronobiology and Sleep Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Nirinjini Naidoo
- Chronobiology and Sleep Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
- Division of Sleep Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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26
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Do MTH. Melanopsin and the Intrinsically Photosensitive Retinal Ganglion Cells: Biophysics to Behavior. Neuron 2019; 104:205-226. [PMID: 31647894 PMCID: PMC6944442 DOI: 10.1016/j.neuron.2019.07.016] [Citation(s) in RCA: 146] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 06/19/2019] [Accepted: 07/12/2019] [Indexed: 12/19/2022]
Abstract
The mammalian visual system encodes information over a remarkable breadth of spatiotemporal scales and light intensities. This performance originates with its complement of photoreceptors: the classic rods and cones, as well as the intrinsically photosensitive retinal ganglion cells (ipRGCs). IpRGCs capture light with a G-protein-coupled receptor called melanopsin, depolarize like photoreceptors of invertebrates such as Drosophila, discharge electrical spikes, and innervate dozens of brain areas to influence physiology, behavior, perception, and mood. Several visual responses rely on melanopsin to be sustained and maximal. Some require ipRGCs to occur at all. IpRGCs fulfill their roles using mechanisms that include an unusual conformation of the melanopsin protein, an extraordinarily slow phototransduction cascade, divisions of labor even among cells of a morphological type, and unorthodox configurations of circuitry. The study of ipRGCs has yielded insight into general topics that include photoreceptor evolution, cellular diversity, and the steps from biophysical mechanisms to behavior.
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Affiliation(s)
- Michael Tri H Do
- F.M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital and Harvard Medical School, Center for Life Science 12061, 3 Blackfan Circle, Boston, MA 02115, USA.
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27
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Michel S, Meijer JH. From clock to functional pacemaker. Eur J Neurosci 2019; 51:482-493. [PMID: 30793396 PMCID: PMC7027845 DOI: 10.1111/ejn.14388] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 01/23/2019] [Accepted: 02/11/2019] [Indexed: 12/17/2022]
Abstract
In mammals, the central pacemaker that coordinates 24‐hr rhythms is located in the suprachiasmatic nucleus (SCN). Individual neurons of the SCN have a molecular basis for rhythm generation and hence, they function as cell autonomous oscillators. Communication and synchronization among these neurons are crucial for obtaining a coherent rhythm at the population level, that can serve as a pace making signal for brain and body. Hence, the ability of single SCN neurons to produce circadian rhythms is equally important as the ability of these neurons to synchronize one another, to obtain a bona fide pacemaker at the SCN tissue level. In this chapter we will discuss the mechanisms underlying synchronization, and plasticity herein, which allows adaptation to changes in day length. Furthermore, we will discuss deterioration in synchronization among SCN neurons in aging, and gain in synchronization by voluntary physical activity or exercise.
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Affiliation(s)
- Stephan Michel
- Group Neurophysiology, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Johanna H Meijer
- Group Neurophysiology, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
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28
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Impaired Circadian Photoentrainment in Opn5-Null Mice. iScience 2018; 6:299-305. [PMID: 30240620 PMCID: PMC6137434 DOI: 10.1016/j.isci.2018.08.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 07/25/2018] [Accepted: 08/10/2018] [Indexed: 12/02/2022] Open
Abstract
The master circadian pacemaker in mammals resides in the hypothalamic suprachiasmatic nuclei (SCN) and is synchronized to ambient light/dark cycles (i.e., photoentrainment). Melanopsin (Opn4) and classical rod-cone photoreceptors are believed to provide all the photic input necessary for circadian photoentrainment. Although the UVA-sensitive photopigment Opn5 is known to be expressed in retinal ganglion cells, its physiological role remains unclear and a potential role for Opn5 in the photoentrainment of the master clock has not been addressed. Here we report impaired photoentrainment and phase shifting to UVA light in Opn5-null mice. However, triple-knockout mice lacking all known functional circadian photoreceptors (i.e., rods, cones, and melanopsin) failed to entrain to UVA-light/dark cycles, despite the presence of Opn5, demonstrating that Opn5 alone is not sufficient for photoentrainment of the SCN clock. Since Opn5 is involved in the regulation of the retinal circadian clock, disrupted retinal function may cause impaired circadian photoentrainment in Opn5-null mice. Opn5-null mice show impaired photoentrainment to UVA-light/dark (LD) cycles Mice lacking melanopsin and functional rods/cones fail to entrain to UVA-LD cycles Opn5 alone is not sufficient for circadian photoentrainment Retinal circadian clocks play a possible role in circadian photoentrainment
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Negelspach DC, Kaladchibachi S, Fernandez F. The circadian activity rhythm is reset by nanowatt pulses of ultraviolet light. Proc Biol Sci 2018; 285:20181288. [PMID: 30068685 PMCID: PMC6111179 DOI: 10.1098/rspb.2018.1288] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 07/09/2018] [Indexed: 12/21/2022] Open
Abstract
The circadian pacemaker synchronizes to the Earth's rotation by tracking step-by-step changes in illumination that occur as the sun passes the horizon. While twilight progressions of irradiance and colour are considered important stimuli in this process, comparably less thought has been given to the possibility that ultraviolet A (UVA) radiation might actually play a more formative role given its evolutionary significance in shaping 24 h timekeeping. Here, we show that Drosophila activity rhythms can be phase-shifted by UVA light at an energy range seated well below that of the visible spectrum. Because the energy threshold for this resetting matches the incident amount of UVA on the human retina at twilight, our results suggest that UVA light has the potential to function as a similar time cue in people.
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Affiliation(s)
| | | | - Fabian Fernandez
- Department of Psychology, University of Arizona, Tucson, AZ, USA
- Department of Neurology, University of Arizona, Tucson, AZ, USA
- BIO5 Institute, University of Arizona, Tucson, AZ, USA
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Hayter EA, Brown TM. Additive contributions of melanopsin and both cone types provide broadband sensitivity to mouse pupil control. BMC Biol 2018; 16:83. [PMID: 30064443 PMCID: PMC6066930 DOI: 10.1186/s12915-018-0552-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 07/20/2018] [Indexed: 01/13/2023] Open
Abstract
Background Intrinsically photosensitive retinal ganglion cells (ipRGCs) drive an array of non-image-forming (NIF) visual responses including circadian photoentrainment and the pupil light reflex. ipRGCs integrate extrinsic (rod/cone) and intrinsic (melanopsin) photoreceptive signals, but the contribution of cones to ipRGC-dependent responses remains incompletely understood. Given recent data revealing that cone-derived colour signals influence mouse circadian timing and pupil responses in humans, here we set out to investigate the role of colour information in pupil control in mice. Results We first recorded electrophysiological activity from the pretectal olivary nucleus (PON) of anaesthetised mice with a red-shifted cone population (Opn1mwR) and mice lacking functional cones (Cnga3−/−) or melanopsin (Opn1mwR; Opn4−/−). Using multispectral stimuli to selectively modulate the activity of individual opsin classes, we show that PON cells which receive ipRGC input also exhibit robust S- and/or L-cone opsin-driven activity. This population includes many cells where the two cone opsins drive opponent responses (most commonly excitatory/ON responses to S-opsin stimulation and inhibitory/OFF responses to L-opsin stimulation). These cone inputs reliably tracked even slow (0.025 Hz) changes in illuminance/colour under photopic conditions with melanopsin contributions becoming increasingly dominant for higher-contrast/lower temporal frequency stimuli. We also evaluated consensual pupil responses in awake animals and show that, surprisingly, this aspect of physiology is insensitive to chromatic signals originating with cones. Instead, by contrast with the situation in humans, signals from melanopsin and both cone opsins combine in a purely additive manner to drive pupil constriction in mice. Conclusion Our data reveal a key difference in the sensory control of the mouse pupil relative to another major target of ipRGCs—the circadian clock. Whereas the latter uses colour information to help estimate time of day, the mouse pupil instead sums signals across cone opsin classes to provide broadband spectral sensitivity to changes in illumination. As such, while the widespread co-occurrence of chromatic responses and melanopsin input in the PON supports a close association between colour discrimination mechanisms and NIF visual processing, our data suggest that colour opponent PON cells in the mouse contribute to functions other than pupil control. Electronic supplementary material The online version of this article (10.1186/s12915-018-0552-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Edward A Hayter
- Faculty of Biology, Medicine and Health, University of Manchester, AV Hill Building, Oxford Road, Manchester, M13 9PT, UK
| | - Timothy M Brown
- Faculty of Biology, Medicine and Health, University of Manchester, AV Hill Building, Oxford Road, Manchester, M13 9PT, UK.
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31
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Schroeder MM, Harrison KR, Jaeckel ER, Berger HN, Zhao X, Flannery MP, St Pierre EC, Pateqi N, Jachimska A, Chervenak AP, Wong KY. The Roles of Rods, Cones, and Melanopsin in Photoresponses of M4 Intrinsically Photosensitive Retinal Ganglion Cells (ipRGCs) and Optokinetic Visual Behavior. Front Cell Neurosci 2018; 12:203. [PMID: 30050414 PMCID: PMC6052130 DOI: 10.3389/fncel.2018.00203] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 06/21/2018] [Indexed: 11/13/2022] Open
Abstract
Intrinsically photosensitive retinal ganglion cells (ipRGCs) mediate not only image-forming vision like other ganglion cells, but also non-image-forming physiological responses to light such as pupil constriction and circadian photoentrainment. All ipRGCs respond to light through their endogenous photopigment melanopsin as well as rod/cone-driven synaptic inputs. A major knowledge gap is how melanopsin, rods, and cones differentially drive ipRGC photoresponses and image-forming vision. We whole-cell-recorded from M4-type ipRGCs lacking melanopsin, rod input, or cone input to dissect the roles of each component in ipRGCs' responses to steady and temporally modulated (≥0.3 Hz) lights. We also used a behavioral assay to determine how the elimination of melanopsin, rod, or cone function impacts the optokinetic visual behavior of mice. Results showed that the initial, transient peak in an M4 cell's responses to 10-s light steps arises from rod and cone inputs. Both the sustainability and poststimulus persistence of these light-step responses depend only on rod and/or cone inputs, which is unexpected because these ipRGC photoresponse properties have often been attributed primarily to melanopsin. For temporally varying stimuli, the enhancement of response sustainedness involves melanopsin, whereas stimulus tracking is mediated by rod and cone inputs. Finally, the behavioral assay showed that while all three photoreceptive systems are nearly equally important for contrast sensitivity, only cones and rods contribute to spatial acuity.
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Affiliation(s)
- Melanie M Schroeder
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Krystal R Harrison
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI, United States.,Department of Molecular, Cellular & Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Elizabeth R Jaeckel
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Hunter N Berger
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Xiwu Zhao
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Michael P Flannery
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Emma C St Pierre
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Nancy Pateqi
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Agnieszka Jachimska
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Andrew P Chervenak
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Kwoon Y Wong
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI, United States.,Department of Molecular, Cellular & Developmental Biology, University of Michigan, Ann Arbor, MI, United States
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Kankanamge D, Ratnayake K, Samaradivakara S, Karunarathne A. Melanopsin (Opn4) utilizes Gα i and Gβγ as major signal transducers. J Cell Sci 2018; 131:jcs.212910. [PMID: 29712722 DOI: 10.1242/jcs.212910] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 04/23/2018] [Indexed: 01/16/2023] Open
Abstract
Melanopsin (Opn4), a ubiquitously expressed photoreceptor in all classes of vertebrates, is crucial for both visual and non-visual signaling. Opn4 supports visual functions of the eye by sensing radiance levels and discriminating contrast and brightness. Non-image-forming functions of Opn4 not only regulate circadian behavior, but also control growth and development processes of the retina. It is unclear how a single photoreceptor could govern such a diverse range of physiological functions; a role in genetic hardwiring could be one explanation, but molecular and mechanistic evidence is lacking. In addition to its role in canonical Gq pathway activation, here we demonstrate that Opn4 efficiently activates Gi heterotrimers and signals through the G protein βγ. Compared with the low levels of Gi pathway activation observed for several Gq-coupled receptors, the robust Gαi and Gβγ signaling of Opn4 led to both generation of PIP3 and directional migration of RAW264.7 macrophages. We propose that the ability of Opn4 to signal through Gαi and Gβγ subunits is a major contributor to its functional diversity.
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Affiliation(s)
- Dinesh Kankanamge
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Kasun Ratnayake
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Saroopa Samaradivakara
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Ajith Karunarathne
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
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33
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Brown TM. Using light to tell the time of day: sensory coding in the mammalian circadian visual network. ACTA ACUST UNITED AC 2017; 219:1779-92. [PMID: 27307539 PMCID: PMC4920240 DOI: 10.1242/jeb.132167] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 05/09/2016] [Indexed: 12/31/2022]
Abstract
Circadian clocks are a near-ubiquitous feature of biology, allowing organisms to optimise their physiology to make the most efficient use of resources and adjust behaviour to maximise survival over the solar day. To fulfil this role, circadian clocks require information about time in the external world. This is most reliably obtained by measuring the pronounced changes in illumination associated with the earth's rotation. In mammals, these changes are exclusively detected in the retina and are relayed by direct and indirect neural pathways to the master circadian clock in the hypothalamic suprachiasmatic nuclei. Recent work reveals a surprising level of complexity in this sensory control of the circadian system, including the participation of multiple photoreceptive pathways conveying distinct aspects of visual and/or time-of-day information. In this Review, I summarise these important recent advances, present hypotheses as to the functions and neural origins of these sensory signals, highlight key challenges for future research and discuss the implications of our current knowledge for animals and humans in the modern world.
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Affiliation(s)
- Timothy M Brown
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
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34
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Abstract
Since the discovery of intrinsic photosensitive retinal ganglion cell (ipRGC) was reported in 2002, many features specific to this cell type have been described. However, scare information is available on the retinographic components directly reflecting ipRGC activity. In this study, we identified the electroretinogram (microERG) that reflects the photoresponses by ipRGCs in ex vivo preparations of the mouse retina, in which classical photoreceptors (cones and rods) were ablated mechanically and photochemically. MicroERG consisted of three components: a large transient ON response, a small and lazy hump 19s after the onset of the light, and a large transient OFF response. A complete microERG recording required at least 30s of light exposure. MicroERG showed the highest spectral photosensitivity at 478nm. This wavelength corresponds to the peak wavelength in the ipRGCs' photosensitive curve. The psychophysical test using a blue light-emitting diode (LED) light (470nm) revealed that the absolute threshold illuminance for microERG was greater than 12.26 log photons/s/cm2 in both ON and OFF responses, whereas microERG was not adapted for dark. The amplitude of microERG increased linearly with irradiance. The sensitivity of temporal frequency was high in microERG (at least 100Hz), as suggested by the study on melatonin suppression by flickering light in human subjects (Zelter et al., 2014). Melatonin secretion was suppressed by light via ipRGCs and the suprachiasmatic nucleus. These properties of the photoresponse indicate that microERG may reflect the functions of ipRGC as a luminance detector in the mouse retina.
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Affiliation(s)
- Motoharu Takao
- Department of Human and Information Science, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan.
| | - Yumi Fukuda
- Department of Living Environmental Science, Fukuoka Women's University, Fukuoka, Fukuoka 813-8529, Japan.
| | - Takeshi Morita
- Department of Living Environmental Science, Fukuoka Women's University, Fukuoka, Fukuoka 813-8529, Japan.
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35
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Stress-Induced Sleep After Exposure to Ultraviolet Light Is Promoted by p53 in Caenorhabditis elegans. Genetics 2017; 207:571-582. [PMID: 28754659 DOI: 10.1534/genetics.117.300070] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 07/24/2017] [Indexed: 12/31/2022] Open
Abstract
Stress-induced sleep (SIS) in Caenorhabditis elegans is important for restoration of cellular homeostasis and is a useful model to study the function and regulation of sleep. SIS is triggered when epidermal growth factor (EGF) activates the ALA neuron, which then releases neuropeptides to promote sleep. To further understand this behavior, we established a new model of SIS using irradiation by ultraviolet C (UVC) light. While UVC irradiation requires ALA signaling and leads to a sleep state similar to that induced by heat and other stressors, it does not induce the proteostatic stress seen with heat exposure. Based on the known genotoxic effects of UVC irradiation, we tested two genes, atl-1 and cep-1, which encode proteins that act in the DNA damage response pathway. Loss-of-function mutants of atl-1 had no defect in UVC-induced SIS but a partial loss-of-function mutant of cep-1, gk138, had decreased movement quiescence following UVC irradiation. Germline ablation experiments and tissue-specific RNA interference experiments showed that cep-1 is required somatically in neurons for its effect on SIS. The cep-1(gk138) mutant suppressed body movement quiescence controlled by EGF, indicating that CEP-1 acts downstream or in parallel to ALA activation to promote quiescence in response to ultraviolet light.
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Abstract
Changes in illumination can rapidly influence behavior that is normally controlled by the circadian clock. This effect is termed masking. In mice, masking requires melanopsin-expressing retinal ganglion cells that detect blue light and project to the thalamus. It is not known whether masking is wavelength-dependent in other vertebrates, nor is it known whether the thalamus is also involved or how it influences masking. Here, we address these questions in zebrafish. We find that diel vertical migration, a circadian behavior in larval zebrafish, is effectively triggered by blue, but not by red light. Two-photon calcium imaging reveals that a thalamic nucleus and a downstream structure, the habenula, have a sustained response to blue but not to red light. Lesioning the habenula reduces light-evoked climbing. These data suggest that the thalamo-habenula pathway is involved in the ability of blue light to influence a circadian behavior.
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Affiliation(s)
- Qian Lin
- NUS Graduate School for Integrative Sciences and Engineering, 28 Medical Drive, National University of Singapore, Singapore, 117456, Singapore.,The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Suresh Jesuthasan
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 636921, Singapore. .,Neural Circuitry and Behavior Laboratory, Institute of Molecular and Cell Biology, Singapore, 138673, Singapore. .,Neuroscience and Behavioral Disorders Program, Duke-NUS Graduate Medical School, 8 College Road, Singapore, 169857, Singapore. .,Department of Physiology, National University of Singapore, Singapore, 117597, Singapore.
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37
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Hawkins P, Golledge HDR. The 9 to 5 Rodent - Time for Change? Scientific and animal welfare implications of circadian and light effects on laboratory mice and rats. J Neurosci Methods 2017; 300:20-25. [PMID: 28502554 DOI: 10.1016/j.jneumeth.2017.05.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 05/07/2017] [Accepted: 05/09/2017] [Indexed: 10/19/2022]
Abstract
Rodents, particularly rats and mice, are the most commonly used laboratory animals and are extensively used in neuroscience research, including as translational models for human disorders. It is common practice to carry out scientific procedures on rats and mice during the daytime, which is the inactive period for these nocturnal species. However, there is increasing evidence for circadian and light-induced effects on rodent physiology and behaviour which may affect the validity of results obtained from mice and rats in neuroscience studies. For example, testing animals during their inactive periods may produce abnormal results due to cognitive deficits, lack of motivation to perform the task or stress from being disturbed during the resting period. In addition, conducting procedures during an animal's resting period may also pose an animal welfare issue, as procedures may be experienced as more stressful than if these were done during the active phase. In this paper we set out the need to consider the impact of time of day and lighting conditions, when scientific procedures or routine husbandry are performed, on both the welfare of mice and rats used in neuroscience research and on data quality. Wherever possible, husbandry and experimental procedures should be conducted at times of day when the animals would be active, and under naturalistic lighting conditions, to minimise stress and maximise data quality and translatability.
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Affiliation(s)
- Penny Hawkins
- Research Animals Department, Royal Society for the Prevention of Cruelty to Animals, Southwater, UK.
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38
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Hanna L, Walmsley L, Pienaar A, Howarth M, Brown TM. Geniculohypothalamic GABAergic projections gate suprachiasmatic nucleus responses to retinal input. J Physiol 2017; 595:3621-3649. [PMID: 28217893 DOI: 10.1113/jp273850] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 02/13/2017] [Indexed: 01/28/2023] Open
Abstract
KEY POINTS Visual input to the suprachiasmatic nucleus circadian clock is critical for animals to adapt their physiology and behaviour in line with the solar day. In addition to direct retinal projections, the clock receives input from the visual thalamus, although the role of this geniculohypothalamic pathway in circadian photoreception is poorly understood. In the present study, we develop a novel brain slice preparation that preserves the geniculohypothalamic pathway to show that GABAergic thalamic neurons inhibit retinally-driven activity in the central clock in a circadian time-dependent manner. We also show that in vivo manipulation of thalamic signalling adjusts specific features of the hypothalamic light response, indicating that the geniculohypothalamic pathway is primarily activated by crossed retinal inputs. Our data provide a mechanism by which geniculohypothalamic signals can adjust the magnitude of circadian and more acute hypothalamic light responses according to time-of-day and establish an important new model for future investigations of the circadian visual system. ABSTRACT Sensory input to the master mammalian circadian clock, the suprachiasmatic nucleus (SCN), is vital in allowing animals to optimize physiology and behaviour alongside daily changes in the environment. Retinal inputs encoding changes in external illumination provide the principle source of such information. The SCN also receives input from other retinorecipient brain regions, primarily via the geniculohypothalamic tract (GHT), although the contribution of these indirect projections to circadian photoreception is currently poorly understood. To address this deficit, in the present study, we established an in vitro mouse brain slice preparation that retains connectivity across the extended circadian system. Using multi-electrode recordings, we first confirm that this preparation retains intact optic projections to the SCN, thalamus and pretectum and a functional GHT. We next show that optogenetic activation of GHT neurons selectively suppresses SCN responses to retinal input, and also that this effect exhibits a pronounced day/night variation and involves a GABAergic mechanism. This inhibitory action was not associated with overt circadian rhythmicity in GHT output, indicating modulation at the SCN level. Finally, we use in vivo electrophysiological recordings alongside pharmacological inactivation or optogenetic excitation to show that GHT signalling actively modulates specific features of the SCN light response, indicating that GHT cells are primarily activated by crossed retinal projections. Taken together, our data establish a new model for studying network communication in the extended circadian system and provide novel insight into the roles of GHT-signalling, revealing a mechanism by which thalamic activity can help gate retinal input to the SCN according to time of day.
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Affiliation(s)
- Lydia Hanna
- Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
| | - Lauren Walmsley
- Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
| | - Abigail Pienaar
- Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
| | - Michael Howarth
- Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
| | - Timothy M Brown
- Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
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Keenan WT, Rupp AC, Ross RA, Somasundaram P, Hiriyanna S, Wu Z, Badea TC, Robinson PR, Lowell BB, Hattar SS. A visual circuit uses complementary mechanisms to support transient and sustained pupil constriction. eLife 2016; 5:e15392. [PMID: 27669145 PMCID: PMC5079752 DOI: 10.7554/elife.15392] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 09/22/2016] [Indexed: 12/22/2022] Open
Abstract
Rapid and stable control of pupil size in response to light is critical for vision, but the neural coding mechanisms remain unclear. Here, we investigated the neural basis of pupil control by monitoring pupil size across time while manipulating each photoreceptor input or neurotransmitter output of intrinsically photosensitive retinal ganglion cells (ipRGCs), a critical relay in the control of pupil size. We show that transient and sustained pupil responses are mediated by distinct photoreceptors and neurotransmitters. Transient responses utilize input from rod photoreceptors and output by the classical neurotransmitter glutamate, but adapt within minutes. In contrast, sustained responses are dominated by non-conventional signaling mechanisms: melanopsin phototransduction in ipRGCs and output by the neuropeptide PACAP, which provide stable pupil maintenance across the day. These results highlight a temporal switch in the coding mechanisms of a neural circuit to support proper behavioral dynamics.
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Affiliation(s)
| | - Alan C Rupp
- Department of Biology, Johns Hopkins University, Baltimore, United States
| | - Rachel A Ross
- Department of Psychiatry, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, United States
- Department of Psychiatry, Massachusetts General Hospital, Boston, United States
| | - Preethi Somasundaram
- Department of Biological Sciences, University of Marlyand, Baltimore, United States
| | - Suja Hiriyanna
- National Eye Institute, National Institutes of Health, Bethesda, United States
| | - Zhijian Wu
- National Eye Institute, National Institutes of Health, Bethesda, United States
| | - Tudor C Badea
- National Eye Institute, National Institutes of Health, Bethesda, United States
| | - Phyllis R Robinson
- Department of Biological Sciences, University of Marlyand, Baltimore, United States
| | - Bradford B Lowell
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, United States
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, United States
- Program in Neuroscience, Harvard Medical School, Boston, United States
| | - Samer S Hattar
- Department of Biology, Johns Hopkins University, Baltimore, United States
- Department of Neuroscience, Johns Hopkins University, Baltimore, United States
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40
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Tamaru T, Ikeda M. Circadian adaptation to cell injury stresses: a crucial interplay of BMAL1 and HSF1. J Physiol Sci 2016; 66:303-6. [PMID: 26910317 PMCID: PMC10717996 DOI: 10.1007/s12576-016-0436-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 02/02/2016] [Indexed: 10/22/2022]
Abstract
The circadian clock system confers daily anticipatory physiological processes with the ability to be reset by environmental cues. This "circadian adaptation system" (CAS), driven by cell-autonomous molecular clocks, orchestrates various rhythmic physiological processes in the entire body. Hence, the dysfunction of these clocks exacerbates various diseases, which may partially be due to the impairment of protective pathways. If this is the case, how does the CAS respond to cell injury stresses that are critical in maintaining health and life by evoking protective pathways? To address this question, here we review and discuss recent evidence revealing life-protective (pro-survival) molecular networks between clock (e.g., BMAL1, CLOCK, and PER2) and adaptation (e.g., HSF1, Nrf2, NF-κB, and p53) pathways, which are evoked by various cell injury stresses (e.g., heat, reactive oxygen species, and UV). The CK2 protein kinase-integrated interplay of the BMAL1 (clock) and HSF1 (heat-shock response) pathways is one of the crucial events in CAS.
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Affiliation(s)
- Teruya Tamaru
- Department of Physiology and Advanced Research Center for Medical Science, Toho University School of Medicine, 5-21-16 Ohmori-nishi Ohta-ku, Tokyo, 143-8540, Japan.
| | - Masaaki Ikeda
- Department of Physiology, Faculty of Medicine, Saitama Medical University, 38 Morohongo Moroyama-machi, Iruma-gun, Saitama, 350-0495, Japan
- Molecular Clock Project, Project Research Division, Research Center for Genomic Medicine, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama, 350-1241, Japan
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41
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Coomans CP, Lucassen EA, Kooijman S, Fifel K, Deboer T, Rensen PCN, Michel S, Meijer JH. Plasticity of circadian clocks and consequences for metabolism. Diabetes Obes Metab 2015; 17 Suppl 1:65-75. [PMID: 26332970 DOI: 10.1111/dom.12513] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 05/17/2015] [Indexed: 12/11/2022]
Abstract
The increased prevalence of metabolic disorders and obesity in modern society, together with the widespread use of artificial light at night, have led researchers to investigate whether altered patterns of light exposure contribute to metabolic disorders. This article discusses the experimental evidence that perturbed environmental cycles induce rhythm disorders in the circadian system, thus leading to metabolic disorders. This notion is generally supported by animal studies. Distorted environmental cycles, including continuous exposure to light, affect the neuronal organization of the central circadian pacemaker in the suprachiasmatic nucleus (SCN), its waveform and amplitude of the rhythm in electrical activity. Moreover, repeated exposure to a shifted light cycle or the application of dim light at night are environmental cues that cause a change in SCN function. The effects on the SCN waveform are the result of changes in synchronization among the SCN's neuronal cell population, which lead consistently to metabolic disturbances. Furthermore, we discuss the effects of sleep deprivation and the time of feeding on metabolism, as these factors are associated with exposure to disturbed environmental cycles. Finally, we suggest that these experimental studies reveal a causal relationship between the rhythm disorders and the metabolic disorders observed in epidemiological studies performed in humans.
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Affiliation(s)
- C P Coomans
- Department of Molecular Cell Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Leiden, Netherlands
| | - E A Lucassen
- Department of Molecular Cell Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Leiden, Netherlands
| | - S Kooijman
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, Netherlands
| | - K Fifel
- Department of Molecular Cell Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Leiden, Netherlands
| | - T Deboer
- Department of Molecular Cell Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Leiden, Netherlands
| | - P C N Rensen
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, Netherlands
| | - S Michel
- Department of Molecular Cell Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Leiden, Netherlands
| | - J H Meijer
- Department of Molecular Cell Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Leiden, Netherlands
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42
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Muindi F, Colas D, Ikeme J, Ruby NF, Heller HC. Loss of Melanopsin Photoreception and Antagonism of the Histamine H3 Receptor by Ciproxifan Inhibit Light-Induced Sleep in Mice. PLoS One 2015; 10:e0128175. [PMID: 26083020 PMCID: PMC4471207 DOI: 10.1371/journal.pone.0128175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 04/24/2015] [Indexed: 12/17/2022] Open
Abstract
Light has direct effects on sleep and wakefulness causing arousal in diurnal animals and sleep in nocturnal animals. In the present study, we assessed the modulation of light-induced sleep by melanopsin and the histaminergic system by exposing mice to millisecond light flashes and continuous light respectively. First, we show that the induction of sleep by millisecond light flashes is dose dependent as a function of light flash number. We found that exposure to 60 flashes of light occurring once every 60 seconds for 1-h (120-ms of total light over an hour) induced a similar amount of sleep as a continuous bright light pulse. Secondly, the induction of sleep by millisecond light flashes was attenuated in the absence of melanopsin when animals were presented with flashes occurring every 60 seconds over a 3-h period beginning at ZT13. Lastly, the acute administration of a histamine H3 autoreceptor antagonist, ciproxifan, blocked the induction of sleep by a 1-h continuous light pulse during the dark period. Ciproxifan caused a decrease in NREMS delta power and an increase in theta activity during both sleep and wake periods respectively. The data suggest that some form of temporal integration occurs in response to millisecond light flashes, and that this process requires melanopsin photoreception. Furthermore, the pharmacological data suggest that the increase of histaminergic neurotransmission is sufficient to attenuate the light-induced sleep response during the dark period.
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Affiliation(s)
- Fanuel Muindi
- Department of Biology, Stanford University, Stanford, California, United States of America
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- * E-mail:
| | - Damien Colas
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Jesse Ikeme
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Norman F. Ruby
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - H. Craig Heller
- Department of Biology, Stanford University, Stanford, California, United States of America
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43
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Abstract
Circadian rhythms are an essential property of life on Earth. In mammals, these rhythms are coordinated by a small set of neurons, located in the suprachiasmatic nuclei (SCN). The environmental light/dark cycle synchronizes (entrains) the SCN via a distinct pathway, originating in a subset of photosensitive retinal ganglion cells (pRGCs) that utilize the photopigment melanopsin (OPN4). The pRGCs are also innervated by rods and cones and, so, are both endogenously and exogenously light sensitive. Accumulating evidence has shown that the circadian system is sensitive to ultraviolet (UV), blue, and green wavelengths of light. However, it was unclear whether colour perception itself can help entrain the SCN. By utilizing both behavioural and electrophysiological recording techniques, Walmsley and colleagues show that multiple photic channels interact and enhance the capacity of the SCN to synchronize to the environmental cycle. Thus, entrainment of the circadian system combines both environmental irradiance and colour information to ensure that internal and external time are appropriately aligned. New evidence reveals that entrainment of the circadian clock combines both environmental irradiance and color information to ensure that internal and external time are appropriately aligned.
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Affiliation(s)
- Hester C. van Diepen
- Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University medical School, Leiden, The Netherlands
- Nuffield Laboratory of Ophthalmology; Sleep and Circadian Neuroscience Institute (SCNi) Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Russell G. Foster
- Nuffield Laboratory of Ophthalmology; Sleep and Circadian Neuroscience Institute (SCNi) Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Johanna H. Meijer
- Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University medical School, Leiden, The Netherlands
- * E-mail:
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Walmsley L, Hanna L, Mouland J, Martial F, West A, Smedley AR, Bechtold DA, Webb AR, Lucas RJ, Brown TM. Colour as a signal for entraining the mammalian circadian clock. PLoS Biol 2015; 13:e1002127. [PMID: 25884537 PMCID: PMC4401556 DOI: 10.1371/journal.pbio.1002127] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 03/11/2015] [Indexed: 11/18/2022] Open
Abstract
Twilight is characterised by changes in both quantity (“irradiance”) and quality (“colour”) of light. Animals use the variation in irradiance to adjust their internal circadian clocks, aligning their behaviour and physiology with the solar cycle. However, it is currently unknown whether changes in colour also contribute to this entrainment process. Using environmental measurements, we show here that mammalian blue–yellow colour discrimination provides a more reliable method of tracking twilight progression than simply measuring irradiance. We next use electrophysiological recordings to demonstrate that neurons in the mouse suprachiasmatic circadian clock display the cone-dependent spectral opponency required to make use of this information. Thus, our data show that some clock neurons are highly sensitive to changes in spectral composition occurring over twilight and that this input dictates their response to changes in irradiance. Finally, using mice housed under photoperiods with simulated dawn/dusk transitions, we confirm that spectral changes occurring during twilight are required for appropriate circadian alignment under natural conditions. Together, these data reveal a new sensory mechanism for telling time of day that would be available to any mammalian species capable of chromatic vision. Environmental measurements and physiological recordings reveal that mice not only use changes in the intensity of sunlight to entrain their circadian clock, but also employ blue–yellow color discrimination to detect spectral changes associated with dawn and dusk. Animals use an internal brain clock to keep track of time and adjust their behaviour in anticipation of the coming day or night. To be useful, however, this clock must be synchronised to external time. Assessing external time is typically thought to rely on measuring large changes in ambient light intensity that occur over dawn/dusk. The colour of light also changes over these twilight transitions, but it is currently unknown whether such changes in colour are important for synchronising biological clocks to the solar cycle. Here we show that the mammalian blue–yellow colour discrimination axis provides a more reliable indication of twilight progression than a system solely measuring changes in light intensity. We go on to use electrical recordings from the brain clock to reveal the presence of many neurons that can track changes in blue–yellow colour occurring during natural twilight. Finally, using mice housed under lighting regimes with simulated dawn/dusk transitions, we show that changes in colour are required for appropriate biological timing with respect to the solar cycle. In sum, our data reveal a new sensory mechanism for estimating time of day that should be available to all mammals capable of chromatic vision, including humans.
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Affiliation(s)
- Lauren Walmsley
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Lydia Hanna
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Josh Mouland
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Franck Martial
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Alexander West
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Andrew R. Smedley
- School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, United Kingdom
| | - David A. Bechtold
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Ann R. Webb
- School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, United Kingdom
| | - Robert J. Lucas
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
- * E-mail: (RJL); (TMB)
| | - Timothy M. Brown
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
- * E-mail: (RJL); (TMB)
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45
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García-Fernández JM, Cernuda-Cernuda R, Davies WIL, Rodgers J, Turton M, Peirson SN, Follett BK, Halford S, Hughes S, Hankins MW, Foster RG. The hypothalamic photoreceptors regulating seasonal reproduction in birds: a prime role for VA opsin. Front Neuroendocrinol 2015; 37:13-28. [PMID: 25448788 DOI: 10.1016/j.yfrne.2014.11.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 10/25/2014] [Accepted: 11/02/2014] [Indexed: 01/30/2023]
Abstract
Extraretinal photoreceptors located within the medio-basal hypothalamus regulate the photoperiodic control of seasonal reproduction in birds. An action spectrum for this response describes an opsin photopigment with a λmax of ∼ 492 nm. Beyond this however, the specific identity of the photopigment remains unresolved. Several candidates have emerged including rod-opsin; melanopsin (OPN4); neuropsin (OPN5); and vertebrate ancient (VA) opsin. These contenders are evaluated against key criteria used routinely in photobiology to link orphan photopigments to specific biological responses. To date, only VA opsin can easily satisfy all criteria and we propose that this photopigment represents the prime candidate for encoding daylength and driving seasonal breeding in birds. We also show that VA opsin is co-expressed with both gonadotropin-releasing hormone (GnRH) and arginine-vasotocin (AVT) neurons. These new data suggest that GnRH and AVT neurosecretory pathways are endogenously photosensitive and that our current understanding of how these systems are regulated will require substantial revision.
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Affiliation(s)
- José M García-Fernández
- Departamento de Morfología y Biología Celular, Universidad de Oviedo, INEUROPA (Instituto de Neurociencias del Principado de Asturias), Spain
| | - Rafael Cernuda-Cernuda
- Departamento de Morfología y Biología Celular, Universidad de Oviedo, INEUROPA (Instituto de Neurociencias del Principado de Asturias), Spain
| | - Wayne I L Davies
- School of Animal Biology and University of Western Australia Oceans Institute, University of Western Australia, Perth, Western Australia, Australia
| | - Jessica Rodgers
- Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom
| | - Michael Turton
- Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom
| | - Stuart N Peirson
- Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom
| | - Brian K Follett
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom.eNuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom
| | - Stephanie Halford
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom
| | - Steven Hughes
- Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom
| | - Mark W Hankins
- Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom
| | - Russell G Foster
- Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom.
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46
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Abstract
Sleep is expressed as a circadian rhythm and the two phenomena exist in a poorly understood relationship. Light affects each, simultaneously influencing rhythm phase and rapidly inducing sleep. Light has long been known to modulate sleep, but recent discoveries support its use as an effective nocturnal stimulus for eliciting sleep in certain rodents. “Photosomnolence” is mediated by classical and ganglion cell photoreceptors and occurs despite the ongoing high levels of locomotion at the time of stimulus onset. Brief photic stimuli trigger rapid locomotor suppression, sleep, and a large drop in core body temperature (Tc; Phase 1), followed by a relatively fixed duration interval of sleep (Phase 2) and recovery (Phase 3) to pre-sleep activity levels. Additional light can lengthen Phase 2. Potential retinal pathways through which the sleep system might be light-activated are described and the potential roles of orexin (hypocretin) and melanin-concentrating hormone are discussed. The visual input route is a practical avenue to follow in pursuit of the neural circuitry and mechanisms governing sleep and arousal in small nocturnal mammals and the organizational principles may be similar in diurnal humans. Photosomnolence studies are likely to be particularly advantageous because the timing of sleep is largely under experimenter control. Sleep can now be effectively studied using uncomplicated, nonintrusive methods with behavior evaluation software tools; surgery for EEG electrode placement is avoidable. The research protocol for light-induced sleep is easily implemented and useful for assessing the effects of experimental manipulations on the sleep induction pathway. Moreover, the experimental designs and associated results benefit from a substantial amount of existing neuroanatomical and pharmacological literature that provides a solid framework guiding the conduct and interpretation of future investigations.
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47
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Walmsley L, Brown TM. Eye-specific visual processing in the mouse suprachiasmatic nuclei. J Physiol 2015; 593:1731-43. [PMID: 25652666 DOI: 10.1113/jphysiol.2014.288225] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 01/27/2015] [Indexed: 01/11/2023] Open
Abstract
Internal circadian clocks are important regulators of mammalian biology, acting to coordinate physiology and behaviour in line with daily changes in the environment. At present, synchronisation of the circadian system to the solar cycle is believed to rely on a quantitative assessment of total ambient illumination, provided by a bilateral projection from the retina to the suprachiasmatic nuclei (SCN). It is currently unclear, however, whether this photic integration occurs at the level of individual cells or within the SCN network. Here we use extracellular multielectrode recordings from the SCN of anaesthetised mice to show that most SCN neurons receive visual input from just one eye. While we find that binocular inputs to a subset of cells are important for rapid responses to changes in illumination, we find no evidence indicating that individual SCN cells are capable of reporting the average light intensity across the whole visual field. As a result of these local irradiance coding properties, our data establish that photic integration is primarily mediated at the level of the SCN network and suggest that accurate assessments of global light levels would be impaired by non-uniform illumination of either eye.
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Affiliation(s)
- Lauren Walmsley
- Faculty of Life Sciences, University of Manchester, Manchester, UK
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48
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Meijer JH, Michel S. Neurophysiological Analysis of the Suprachiasmatic Nucleus. Methods Enzymol 2015; 552:75-102. [DOI: 10.1016/bs.mie.2014.11.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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49
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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.
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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.
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50
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Jayanthy A, Setaluri V. Light-regulated microRNAs. Photochem Photobiol 2014; 91:163-72. [PMID: 25389067 DOI: 10.1111/php.12386] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 10/27/2014] [Indexed: 02/06/2023]
Abstract
In addition to exposure to passive diurnal cycles of sunlight, humans are also subjected to intentional acute exposure to other types of electromagnetic radiation (EM). Understanding the molecular mechanisms involved in the physiological, pathological and therapeutic responses to exposure to radiation is an active area of research. With the advent of methods to readily catalog and identify patterns of changes in gene expression, many studies have reported changes in gene expression upon exposure of various human and mouse cells in vitro, whole experimental organisms such as mice and parts of human body. However, the molecular mechanisms underlying these broad ranging changes in gene expression are not yet fully understood. MicroRNAs, which are short, noncoding RNAs that regulate gene expression by targeting many messenger RNAs, are also emerging as important mediators of radiation-induced changes in gene expression and hence critical for the manifestation of light-induced cellular phenotypes and physiological responses. In this article, we review available knowledge on microRNAs implicated in responses to various forms of solar and other EM radiation. Based on this knowledge, we elaborate some unifying themes in the regulation and functions of some of these miRNAs.
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Affiliation(s)
- Ashika Jayanthy
- Department of Dermatology and Graduate Program in Comparative Biomedical Sciences, School of Medicine and Public Health & School of Veterinary Medicine, University of Wisconsin, Madison, WI
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