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Rohr KE, Inda T, Evans JA. Vasopressin Resets the Central Circadian Clock in a Manner Influenced by Sex and Vasoactive Intestinal Polypeptide Signaling. Neuroendocrinology 2022; 112:904-916. [PMID: 34856551 PMCID: PMC9160207 DOI: 10.1159/000521286] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 12/01/2021] [Indexed: 01/03/2023]
Abstract
BACKGROUND/AIMS Circadian rhythms in behavior and physiology are programmed by the suprachiasmatic nucleus (SCN) of the hypothalamus. A subset of SCN neurons produce the neuropeptide arginine vasopressin (AVP), but it remains unclear whether AVP signaling influences the SCN clock directly. METHODS Here, we test that AVP signaling acting through V1A and V1B receptors influences molecular rhythms in SCN neurons. V1 receptor agonists were applied ex vivo to PERIOD2::LUCIFERASE SCN slices, allowing for real-time monitoring of changes in molecular clock function. RESULTS V1A/B agonists reset the phase of the SCN molecular clock in a time-dependent manner, with larger magnitude responses by the female SCN. Further, we found evidence that both Gαq and Gαs signaling pathways interact with V1A/B-induced SCN resetting, and that this response requires vasoactive intestinal polypeptide (VIP) signaling. CONCLUSIONS Collectively, this work indicates that AVP signaling resets SCN molecular rhythms in conjunction with VIP signaling and in a manner influenced by sex. This highlights the utility of studying clock function in both sexes and suggests that signal integration in central clock circuits regulates emergent properties important for the control of daily rhythms in behavior and physiology.
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Affiliation(s)
| | | | - Jennifer A. Evans
- Corresponding author: 560 N 16 St, Schroeder Complex, Room 446, Milwaukee, WI 53233, Phone: 414 288-5732, Fax: 414-288-6564,
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2
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Gottlieb LA, Larsen K, Halade GV, Young ME, Thomsen MB. Prolonged QT intervals in mice with cardiomyocyte-specific deficiency of the molecular clock. Acta Physiol (Oxf) 2021; 233:e13707. [PMID: 34176211 DOI: 10.1111/apha.13707] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 06/11/2021] [Accepted: 06/25/2021] [Indexed: 12/19/2022]
Abstract
AIM Cardiac arrhythmias and sudden deaths have diurnal rhythms in humans. The underlying mechanisms are unknown. Mice with cardiomyocyte-specific disruption of the molecular clock genes have lower heart rate than control. Because changes in the QT interval on the electrocardiogram is a clinically used marker of risk of arrhythmias, we sought to test if the biological rhythms of QT intervals are dependent on heart rate and if this dependency is changed when the molecular clock is disrupted. METHODS We implanted radio transmitters in male mice with cardiomyocyte-specific Bmal1 knockout (CBK) and in control mice and recorded 24-h ECGs under diurnal and circadian conditions. We obtained left ventricular monophasic action potentials during pacing in hearts ex vivo. RESULTS Both RR and QT intervals were longer in conscious CBK than control mice (RR: 117 ± 7 vs 110 ± 9 ms, P < .05; and QT: 53 ± 4 vs 48 ± 2 ms, P < .05). The prolonged QT interval was independent of the slow heart rate in CBK mice. The QT interval exhibited diurnal and circadian rhythms in both CBK and control mice. The action potential duration was longer in CBK than in control mice, indicating slower repolarization. Action potential alternans occurred at lower pacing rate in hearts from CBK than control mice (12 ± 3 vs 16 ± 2 Hz, respectively, P < .05). CONCLUSION The bradycardic CBK mice have prolonged ventricular repolarization independent of the heart rate. Diurnal and circadian rhythms in repolarization are preserved in CBK mice and are not a consequence of the 24-h rhythm in heart rate. Arrhythmia vulnerability appears to be increased when the cardiac clock is disrupted.
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Affiliation(s)
- Lisa A. Gottlieb
- Department of Biomedical Sciences University of Copenhagen Denmark
- Department of Experimental Cardiology Amsterdam University Medical Centerlocatie AMC Amsterdam the Netherlands
| | - Karin Larsen
- Department of Biomedical Sciences University of Copenhagen Denmark
| | - Ganesh V. Halade
- Division of Cardiovascular Sciences Department of Medicine University of South Florida Tampa FL USA
| | - Martin E. Young
- Department of Medicine University of Alabama at Birmingham AL USA
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3
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Exposure to Short Wavelength-Enriched White Light and Exercise Improves Alertness and Performance in Operational NASA Flight Controllers Working Overnight Shifts. J Occup Environ Med 2021; 63:111-118. [PMID: 33065729 DOI: 10.1097/jom.0000000000002054] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE We evaluated the efficacy of a combined short-wavelength-enriched white light and exercise fatigue countermeasure during breaks for flight controllers working overnight shifts. METHODS Twenty NASA flight controllers were studied for two blocks of nightshifts in ISS mission control, randomized to either the control or countermeasure condition. The countermeasure constituted passive exposure to blue-enriched polychromatic lighting for three 20-minute intervals, which included 10 minutes of exercise and occurred before and twice during their shifts. Alertness, performance, and mood were evaluated. RESULTS Flight controllers reported being significantly more alert (P < 0.0001) and happy (P = 0.003) and had faster reaction times (10% slowest responses; P < 0.05) during the countermeasure condition compared to control. CONCLUSIONS The combined light and exercise countermeasure improved alertness, performance, and mood in shift workers overnight. Further research is necessary to determine their relative contribution.
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Zheng X, Zhang K, Zhao Y, Fent K. Environmental chemicals affect circadian rhythms: An underexplored effect influencing health and fitness in animals and humans. ENVIRONMENT INTERNATIONAL 2021; 149:106159. [PMID: 33508534 DOI: 10.1016/j.envint.2020.106159] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 09/21/2020] [Accepted: 09/21/2020] [Indexed: 06/12/2023]
Abstract
Circadian rhythms control the life of virtually all organisms. They regulate numerous aspects ranging from cellular processes to reproduction and behavior. Besides the light-dark cycle, there are additional environmental factors that regulate the circadian rhythms in animals as well as humans. Here, we outline the circadian rhythm system and considers zebrafish (Danio rerio) as a representative vertebrate organism. We characterize multiple physiological processes, which are affected by circadian rhythm disrupting compounds (circadian disrupters). We focus on and summarize 40 natural and anthropogenic environmental circadian disrupters in fish. They can be divided into six major categories: steroid hormones, metals, pesticides and biocides, polychlorinated biphenyls, neuroactive drugs and other compounds such as cyanobacterial toxins and bisphenol A. Steroid hormones as well as metals are most studied. Especially for progestins and glucocorticoids, circadian dysregulation was demonstrated in zebrafish on the molecular and physiological level, which comprise mainly behavioral alterations. Our review summarizes the current state of knowledge on circadian disrupters, highlights their risks to fish and identifies knowledge gaps in animals and humans. While most studies focus on transcriptional and behavioral alterations, additional effects and consequences are underexplored. Forthcoming studies should explore, which additional environmental circadian disrupters exist. They should clarify the underlying molecular mechanisms and aim to better understand the consequences for physiological processes.
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Affiliation(s)
- Xuehan Zheng
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Kun Zhang
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Yanbin Zhao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
| | - Karl Fent
- University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Hofackerstrasse 30, CH-4132 Muttenz, Switzerland; ETH Zürich, Institute of Biogeochemistry and Pollution Dynamics, Department of Environmental Systems Science, CH-8092 Zürich, Switzerland.
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5
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Jha PK, Bouâouda H, Kalsbeek A, Challet E. Distinct feedback actions of behavioural arousal to the master circadian clock in nocturnal and diurnal mammals. Neurosci Biobehav Rev 2021; 123:48-60. [PMID: 33440199 DOI: 10.1016/j.neubiorev.2020.12.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 09/16/2020] [Accepted: 12/10/2020] [Indexed: 12/20/2022]
Abstract
The master clock in the suprachiasmatic nucleus (SCN) of the hypothalamus provides a temporal pattern of sleep and wake that - like many other behavioural and physiological rhythms - is oppositely phased in nocturnal and diurnal animals. The SCN primarily uses environmental light, perceived through the retina, to synchronize its endogenous circadian rhythms with the exact 24 h light/dark cycle of the outside world. The light responsiveness of the SCN is maximal during the night in both nocturnal and diurnal species. Behavioural arousal during the resting period not only perturbs sleep homeostasis, but also acts as a potent non-photic synchronizing cue. The feedback action of arousal on the SCN is mediated by processes involving several brain nuclei and neurotransmitters, which ultimately change the molecular functions of SCN pacemaker cells. Arousing stimuli during the sleeping period differentially affect the circadian system of nocturnal and diurnal species, as evidenced by the different circadian windows of sensitivity to behavioural arousal. In addition, arousing stimuli reduce and increase light resetting in nocturnal and diurnal species, respectively. It is important to address further question of circadian impairments associated with shift work and trans-meridian travel not only in the standard nocturnal laboratory animals but also in diurnal animal models.
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Affiliation(s)
- Pawan Kumar Jha
- Circadian Clocks and Metabolism Team, Institute of Cellular and Integrative Neurosciences, Centre National de la Recherche Scientifique (CNRS), University of Strasbourg, France; Department of Endocrinology and Metabolism, Amsterdam University Medical Center (AUMC), University of Amsterdam, the Netherlands; Hypothalamic Integration Mechanisms, Netherlands Institute for Neuroscience, Amsterdam, the Netherlands.
| | - Hanan Bouâouda
- Circadian Clocks and Metabolism Team, Institute of Cellular and Integrative Neurosciences, Centre National de la Recherche Scientifique (CNRS), University of Strasbourg, France
| | - Andries Kalsbeek
- Department of Endocrinology and Metabolism, Amsterdam University Medical Center (AUMC), University of Amsterdam, the Netherlands; Hypothalamic Integration Mechanisms, Netherlands Institute for Neuroscience, Amsterdam, the Netherlands
| | - Etienne Challet
- Circadian Clocks and Metabolism Team, Institute of Cellular and Integrative Neurosciences, Centre National de la Recherche Scientifique (CNRS), University of Strasbourg, France
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6
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Good CH, Brager AJ, Capaldi VF, Mysliwiec V. Sleep in the United States Military. Neuropsychopharmacology 2020; 45:176-191. [PMID: 31185484 PMCID: PMC6879759 DOI: 10.1038/s41386-019-0431-7] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 05/23/2019] [Accepted: 05/31/2019] [Indexed: 02/07/2023]
Abstract
The military lifestyle often includes continuous operations whether in training or deployed environments. These stressful environments present unique challenges for service members attempting to achieve consolidated, restorative sleep. The significant mental and physical derangements caused by degraded metabolic, cardiovascular, skeletomuscular, and cognitive health often result from insufficient sleep and/or circadian misalignment. Insufficient sleep and resulting fatigue compromises personal safety, mission success, and even national security. In the long-term, chronic insufficient sleep and circadian rhythm disorders have been associated with other sleep disorders (e.g., insomnia, obstructive sleep apnea, and parasomnias). Other physiologic and psychologic diagnoses such as post-traumatic stress disorder, cardiovascular disease, and dementia have also been associated with chronic, insufficient sleep. Increased co-morbidity and mortality are compounded by traumatic brain injury resulting from blunt trauma, blast exposure, and highly physically demanding tasks under load. We present the current state of science in human and animal models specific to service members during- and post-military career. We focus on mission requirements of night shift work, sustained operations, and rapid re-entrainment to time zones. We then propose targeted pharmacological and non-pharmacological countermeasures to optimize performance that are mission- and symptom-specific. We recognize a critical gap in research involving service members, but provide tailored interventions for military health care providers based on the large body of research in health care and public service workers.
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Affiliation(s)
- Cameron H. Good
- 0000 0001 2151 958Xgrid.420282.ePhysical Scientist, US Army Research Laboratory, Aberdeen Proving Ground, MD, 21005 USA
| | - Allison J. Brager
- 0000 0001 0036 4726grid.420210.5Sleep Research Center, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD 20910 USA
| | - Vincent F. Capaldi
- 0000 0001 0036 4726grid.420210.5Department of Behavioral Biology Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, Silver Spring, MD 20910 USA
| | - Vincent Mysliwiec
- 0000 0004 0467 8038grid.461685.8San Antonio Military Health System, Department of Sleep Medicine, JBSA, Lackland, TX 78234 USA
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7
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Weinert D, Schöttner K, Meinecke AC, Hauer J. Voluntary exercise stabilizes photic entrainment of djungarian hamsters (Phodopus sungorus) with a delayed activity onset. Chronobiol Int 2018; 35:1435-1444. [PMID: 29985662 DOI: 10.1080/07420528.2018.1490313] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The Djungarian hamsters of our breeding colony show unstable daily activity patterns when kept under standard laboratory conditions. Moreover, part of them develops a delayed activity onset (DAO) or an arrhythmic phenotype. In former studies, we have shown that the system of photic entrainment works at its limits. If the period length (tau) increases, which is the case in DAO hamsters, the light-induced phase advances are too small to compensate the daily delay of the activity rhythm caused by tau being longer than 24 h. Accordingly, under natural conditions, there must be further (environmental) factors to enable a stable entrainment. One of these may be the higher level of motor activity. Animals must cover long distances to search for food, sexual partners and others. In the laboratory, hamsters are kept singly in small cages. This does restrict animals' options for motor activity. Also, there is less need for moving around as the hamsters are fed ad libitum. In the present study, a series of experiments was performed to investigate the putative effect of the activity level. To begin with, wild type (WT) and DAO animals were given access to running wheels. 50% of DAO hamsters developed a WT activity pattern. As the main reason for the DAO phenomenon is their long tau together with a too weak photic phase response, the effect of wheel running on these parameters was investigated in further experiments. With higher activity level, tau decreased in WT hamsters but increased in DAO animals even though the increase for the activity onset was only close to significance. Moreover, the photic phase responses were weaker though significant only for the activity offset of DAO hamsters. Based on the assumptions that running wheel activity will affect the phase response and/or the free running period, the results of the present paper do not provide an explanation for why part of DAO hamsters developed a WT phenotype when they had access to running wheels. Obviously, mechanisms downstream from the suprachiasmatic nuclei must be taken into account when investigating the stabilizing, improving circadian entrainment effect of motor activity.
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Affiliation(s)
- D Weinert
- a Institute of Biology/Zoology, Martin Luther University Halle-Wittenberg , Halle-Wittenberg , Germany
| | - K Schöttner
- b Center for Studies in Behavioral Neurobiology, Concordia University , Montreal , Canada
| | - A C Meinecke
- a Institute of Biology/Zoology, Martin Luther University Halle-Wittenberg , Halle-Wittenberg , Germany
| | - J Hauer
- a Institute of Biology/Zoology, Martin Luther University Halle-Wittenberg , Halle-Wittenberg , Germany
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8
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Belle MDC, Diekman CO. Neuronal oscillations on an ultra-slow timescale: daily rhythms in electrical activity and gene expression in the mammalian master circadian clockwork. Eur J Neurosci 2018; 48:2696-2717. [PMID: 29396876 DOI: 10.1111/ejn.13856] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 01/16/2018] [Accepted: 01/28/2018] [Indexed: 12/17/2022]
Abstract
Neuronal oscillations of the brain, such as those observed in the cortices and hippocampi of behaving animals and humans, span across wide frequency bands, from slow delta waves (0.1 Hz) to ultra-fast ripples (600 Hz). Here, we focus on ultra-slow neuronal oscillators in the hypothalamic suprachiasmatic nuclei (SCN), the master daily clock that operates on interlocking transcription-translation feedback loops to produce circadian rhythms in clock gene expression with a period of near 24 h (< 0.001 Hz). This intracellular molecular clock interacts with the cell's membrane through poorly understood mechanisms to drive the daily pattern in the electrical excitability of SCN neurons, exhibiting an up-state during the day and a down-state at night. In turn, the membrane activity feeds back to regulate the oscillatory activity of clock gene programs. In this review, we emphasise the circadian processes that drive daily electrical oscillations in SCN neurons, and highlight how mathematical modelling contributes to our increasing understanding of circadian rhythm generation, synchronisation and communication within this hypothalamic region and across other brain circuits.
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Affiliation(s)
- Mino D C Belle
- Institute of Clinical and Biomedical Sciences, University of Exeter Medical School, University of Exeter, Exeter, EX4 4PS, UK
| | - Casey O Diekman
- Department of Mathematical Sciences, New Jersey Institute of Technology, Newark, NJ, USA.,Institute for Brain and Neuroscience Research, New Jersey Institute of Technology, Newark, NJ, USA
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9
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Kiessling S, O'Callaghan EK, Freyburger M, Cermakian N, Mongrain V. The cell adhesion molecule EphA4 is involved in circadian clock functions. GENES BRAIN AND BEHAVIOR 2017; 17:82-92. [PMID: 28425198 DOI: 10.1111/gbb.12387] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 04/11/2017] [Accepted: 04/11/2017] [Indexed: 12/29/2022]
Abstract
Circadian (∼24 h) rhythms of cellular network plasticity in the central circadian clock, the suprachiasmatic nucleus (SCN), have been described. The neuronal network in the SCN regulates photic resetting of the circadian clock as well as stability of the circadian system during both entrained and constant conditions. EphA4, a cell adhesion molecule regulating synaptic plasticity by controlling connections of neurons and astrocytes, is expressed in the SCN. To address whether EphA4 plays a role in circadian photoreception and influences the neuronal network of the SCN, we have analyzed circadian wheel-running behavior of EphA4 knockout (EphA4-/- ) mice under different light conditions and upon photic resetting, as well as their light-induced protein response in the SCN. EphA4-/- mice exhibited reduced wheel-running activity, longer endogenous periods under constant darkness and shorter periods under constant light conditions, suggesting an effect of EphA4 on SCN function. Moreover, EphA4-/- mice exhibited suppressed phase delays of their wheel-running activity following a light pulse during the beginning of the subjective night (CT15). Accordingly, light-induced c-FOS (FBJ murine osteosarcoma viral oncogene homolog) expression was diminished. Our results suggest a circadian role for EphA4 in the SCN neuronal network, affecting the circadian system and contributing to the circadian response to light.
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Affiliation(s)
- S Kiessling
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada.,Present address: Nutrition and Immunology, Technical University of Munich, Freising, Germany
| | - E K O'Callaghan
- Center for Advanced Research in Sleep Medicine and Research Center, Hôpital du Sacré-Coeur de Montréal, Montreal, QC, Canada.,Department of Neuroscience, Université de Montréal, Montreal, QC, Canada
| | - M Freyburger
- Center for Advanced Research in Sleep Medicine and Research Center, Hôpital du Sacré-Coeur de Montréal, Montreal, QC, Canada.,Department of Neuroscience, Université de Montréal, Montreal, QC, Canada
| | - N Cermakian
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada
| | - V Mongrain
- Center for Advanced Research in Sleep Medicine and Research Center, Hôpital du Sacré-Coeur de Montréal, Montreal, QC, Canada.,Department of Neuroscience, Université de Montréal, Montreal, QC, Canada
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10
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Weinert D, Schöttner K, Müller L, Wienke A. Intensive voluntary wheel running may restore circadian activity rhythms and improves the impaired cognitive performance of arrhythmic Djungarian hamsters. Chronobiol Int 2016; 33:1161-1170. [DOI: 10.1080/07420528.2016.1205083] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Dietmar Weinert
- Institute of Biology, Department of Zoology, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Konrad Schöttner
- Institute of Entomology, Biology Centre CAS, Ceske Budejovice, Czech Republic
| | - Lisa Müller
- Institute of Biology, Department of Zoology, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Andreas Wienke
- Institute of Medical Epidemiology, Biometrics and Informatics, Martin Luther University Halle-Wittenberg, Halle, Germany
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11
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Antle MC, Sterniczuk R, Smith VM, Hagel K. Non-Photic Modulation of Phase Shifts to Long Light Pulses. J Biol Rhythms 2016; 22:524-33. [DOI: 10.1177/0748730407306882] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Circadian rhythms can be reset by both photic and non-photic stimuli. Recent studies have used long light exposure to produce photic phase shifts or to enhance non-photic phase shifts. The presence or absence of light can also influence the expression of locomotor rhythms through masking; light during the night attenuates locomotor activity, while darkness during the day induces locomotor activity in nocturnal animals. Given this dual role of light, the current study was designed to examine the relative contributions of photic and non-photic components present in a long light pulse paradigm. Mice entrained to a light/dark cycle were exposed to light pulses of various durations (0, 3, 6, 9, or 12 h) starting at the time of lights-off. After the light exposure, animals were placed in DD and were either left undisturbed in their home cages or had their wheels locked for the remainder of the subjective night and subsequent subjective day. Light treatments of 6, 9, and 12 h produced large phase delays. These treatments were associated with decreased activity during the nocturnal light and increased activity during the initial hours of darkness following light exposure. When the wheels were locked to prevent high-amplitude activity, the resulting phase delays to the light were significantly attenuated, suggesting that the activity following the light exposure may have contributed to the overall phase shift. In a second experiment, telemetry probes were used to assess what effect permanently locking the wheels had on the phase shift to the long light pulses. These animals had phase shifts fully as large as animals without any form of wheel lock, suggesting that while non-photic events can modulate photic phase shifts, they do not play a role in the full phase-shift response observed in animals exposed to long light pulses. This paradigm will facilitate investigations into non-photic responses of the mouse circadian system.
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Affiliation(s)
- Michael C. Antle
- Department of Psychology, University of Calgary, Calgary, AB, Canada, Hotchkiss Brain Institute, Department of Pharmacology & Therapeutics, University of Calgary, Calgary, AB, Canada,
| | | | - Victoria M. Smith
- Department of Psychology, University of Calgary, Calgary, AB, Canada
| | - Kimberly Hagel
- Department of Psychology, University of Calgary, Calgary, AB, Canada
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12
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Schöttner K, Hauer J, Weinert D. Non-parametric photic entrainment of Djungarian hamsters with different rhythmic phenotypes. Chronobiol Int 2016; 33:506-19. [PMID: 27031879 DOI: 10.3109/07420528.2016.1160100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
To investigate the role of non-parametric light effects in entrainment, Djungarian hamsters of two different circadian phenotypes were exposed to skeleton photoperiods, or to light pulses at different circadian times, to compile phase response curves (PRCs). Wild-type (WT) hamsters show daily rhythms of locomotor activity in accord with the ambient light/dark conditions, with activity onset and offset strongly coupled to light-off and light-on, respectively. Hamsters of the delayed activity onset (DAO) phenotype, in contrast, progressively delay their activity onset, whereas activity offset remains coupled to light-on. The present study was performed to better understand the underlying mechanisms of this phenomenon. Hamsters of DAO and WT phenotypes were kept first under standard housing conditions with a 14:10 h light-dark cycle, and then exposed to skeleton photoperiods (one or two 15-min light pulses of 100 lx at the times of the former light-dark and/or dark-light transitions). In a second experiment, hamsters of both phenotypes were transferred to constant darkness and allowed to free-run until the lengths of the active (α) and resting (ρ) periods were equal (α:ρ = 1). At this point, animals were then exposed to light pulses (100 lx, 15 min) at different circadian times (CTs). Phase and period changes were estimated separately for activity onset and offset. When exposed to skeleton-photoperiods with one or two light pulses, the daily activity patterns of DAO and WT hamsters were similar to those obtained under conditions of a complete 14:10 h light-dark cycle. However, in the case of giving only one light pulse at the time of the former light-dark transition, animals temporarily free-ran until activity offset coincided with the light pulse. These results show that photic entrainment of the circadian activity rhythm is attained primarily via non-parametric mechanisms, with the "morning" light pulse being the essential cue. In the second experiment, typical photic PRCs were obtained with phase delays in the first half of the subjective night, phase advances in the second half, and a dead zone during the subjective day. ANOVA indicated no significant differences between WT and DAO animals despite a significantly longer free-running period (tau) in DAO hamsters. Considering the phase shifts induced around CT0 and the different period lengths, it was possible to model the entrainment patterns of both phenotypes. It was shown that light-induced phase shifts of activity offset were sufficient to compensate for the long tau in WT and DAO hamsters, thus enabling a stable entrainment of their activity offsets to be achieved. With respect to activity onsets, phase shifts were sufficient only in WT animals; in DAO hamsters, activity onset showed increasing delays. The results of the present paper clearly demonstrate that, under laboratory conditions, the non-parametric component of light and dark leads to circadian entrainment in Djungarian hamsters. However, a stable entrainment of activity onset can be achieved only if the free-running period does not exceed a certain value. With longer tau values, hamsters reveal a DAO phenotype. Under field conditions, therefore, non-photic cues/zeitgebers must obviously be involved to enable a proper circadian entrainment.
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Affiliation(s)
- Konrad Schöttner
- a Department of Zoology , Institute of Biology/Zoology, Martin-Luther-University Halle-Wittenberg , Halle , Germany.,b Department of Biochemistry and Physiology , Institute of Entomology, Biology Centre CAS , Ceske Budejovice , Czech Republic
| | - Jane Hauer
- a Department of Zoology , Institute of Biology/Zoology, Martin-Luther-University Halle-Wittenberg , Halle , Germany
| | - Dietmar Weinert
- a Department of Zoology , Institute of Biology/Zoology, Martin-Luther-University Halle-Wittenberg , Halle , Germany
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Abstract
Limited research has compared the circadian phase-shifting effects of bright light and exercise and additive effects of these stimuli. The aim of this study was to compare the phase-delaying effects of late night bright light, late night exercise, and late evening bright light followed by early morning exercise. In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols. Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness in dim light for 2h, followed by attempted sleep in darkness for 1 h, repeated throughout each protocol. On night 2 of each protocol, participants received either (1) bright light alone (5,000 lux) from 2210-2340 h, (2) treadmill exercise alone from 2210-2340 h, or (3) bright light (2210-2340 h) followed by exercise from 0410-0540 h. Urine was collected every 90 min. Shifts in the 6-sulphatoxymelatonin (aMT6s) cosine acrophase from baseline to post-treatment were compared between treatments. Analyses revealed a significant additive phase-delaying effect of bright light + exercise (80.8 ± 11.6 [SD] min) compared with exercise alone (47.3 ± 21.6 min), and a similar phase delay following bright light alone (56.6 ± 15.2 min) and exercise alone administered for the same duration and at the same time of night. Thus, the data suggest that late night bright light followed by early morning exercise can have an additive circadian phase-shifting effect.
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14
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Prosser RA, Glass JD. Assessing ethanol's actions in the suprachiasmatic circadian clock using in vivo and in vitro approaches. Alcohol 2015; 49:321-339. [PMID: 25457753 DOI: 10.1016/j.alcohol.2014.07.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 07/07/2014] [Accepted: 07/09/2014] [Indexed: 12/18/2022]
Abstract
Research over the past decade has demonstrated substantial interactions between the circadian system and the processes through which alcohol affects behavior and physiology. Here we summarize the results of our collaborative efforts focused on this intersection. Using a combination of in vivo and in vitro approaches, we have shown that ethanol affects many aspects of the mammalian circadian system, both acutely as well as after chronic administration. Conversely, we have shown circadian influences on ethanol consumption. Importantly, we are beginning to delve into the cellular mechanisms associated with these effects. We are also starting to form a picture of the neuroanatomical bases for many of these actions. Finally, we put our current findings into perspective by suggesting new avenues of inquiry for our future efforts.
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15
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Kallingal GJ, Mintz EM. Site-specific effects of gastrin-releasing peptide in the suprachiasmatic nucleus. Eur J Neurosci 2013; 39:630-9. [PMID: 24528136 DOI: 10.1111/ejn.12411] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 10/07/2013] [Indexed: 11/29/2022]
Abstract
The effects of gastrin-releasing peptide (GRP) on the circadian clock in the suprachiasmatic nucleus (SCN) are dependent on the activation of N-methyl-d-aspartate (NMDA) receptors in the SCN. In this study, the interaction between GRP, glutamate and serotonin in the regulation of circadian phase in Syrian hamsters was evaluated. Microinjection of GRP into the third ventricle induced c-fos and p-ERK expression throughout the SCN. Coadministration of an NMDA antagonist or 8-hydroxy-2-di-n-propylamino-tetralin [a serotonin (5-HT)1A,7 agonist, DPAT] with GRP limited c-fos expression in the SCN to a region dorsal to GRP cell bodies. Similar to the effects of NMDA antagonists, DPAT attenuated GRP-induced phase shifts in the early night, suggesting that the actions of serotonin on the photic phase shifting mechanism occur downstream from retinorecipient cells. c-fos and p-ERK immunoreactivity in the supraoptic (SON) and paraventricular hypothalamic nuclei also increased following ventricular microinjection of GRP. Because of this finding, a second set of experiments was designed to test a potential role for the SON in the regulation of clock function. Syrian hamsters were given microinjections of GRP into the peri-SON during the early night. GRP-induced c-fos activity in the SCN was similar to that following ventricular administration of GRP. GRP or bicuculline (a γ-aminobutyric acidA antagonist) administered near the SON during the early night elicited phase delays of circadian activity rhythms. These data suggest that GRP-induced phase-resetting is dependent on levels of glutamatergic and serotonergic neurotransmission in the SCN and implicate activity in the SON as a potential regulator of photic signaling in the SCN.
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Affiliation(s)
- George J Kallingal
- Department of Biological Sciences and School of Biomedical Sciences, Kent State University, Kent, OH, USA
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16
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Paulus EV, Mintz EM. Photic and nonphotic responses of the circadian clock in serotonin-deficient Pet-1 knockout mice. Chronobiol Int 2013; 30:1251-60. [PMID: 24059871 DOI: 10.3109/07420528.2013.815198] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The neurotransmitter serotonin plays an important role in the regulation of the circadian clock. To gain further insight into the mechanisms by which serotonin regulates rhythmicity, the authors investigated photic and nonphotic effects on the circadian clock in Pet-1 knockout mice. In these mice, the serotonergic system suffers a developmental loss of 70% of serotonin neurons, with the remaining neurons being deficient in serotonergic function as well. Pet-1 knockout mice show significantly decreased phase delays of the circadian clock in response to light pulses in the early night; however, this difference was not reflected in a difference in the expression of Fos protein in the suprachiasmatic nucleus. There were no genotypic differences detected in the phase-shifting response to injection of the 5-HT1A/7 (serotonin 1A and 7) agonist 8-OH-DPAT ((±)-8-hydroxy-2-(dipropylamino)tetralin hydrobromide); however, there were small but significant differences in the phase-shifting responses to cages between genotypes and sexes. Several different patterns of wheel-running activity were observed in knockout mice that differed from those in wild-type mice, suggesting that normal serotonergic function is necessary for the proper consolidation of nocturnal activity. Overall, these data are consistent with other pharmacological and genetic studies demonstrating a significant role for serotonin in circadian clock function.
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Affiliation(s)
- Erin V Paulus
- Department of Biological Sciences and School of Biomedical Sciences, Kent State University , Kent, Ohio , USA
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17
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Vivanco P, Studholme KM, Morin LP. Drugs that prevent mouse sleep also block light-induced locomotor suppression, circadian rhythm phase shifts and the drop in core temperature. Neuroscience 2013; 254:98-109. [PMID: 24056197 DOI: 10.1016/j.neuroscience.2013.09.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 09/10/2013] [Accepted: 09/11/2013] [Indexed: 02/08/2023]
Abstract
Exposure of mice to a brief light stimulus during their nocturnal active phase induces several simultaneous behavioral or physiological responses, including circadian rhythm phase shifts, a drop in core body temperature (Tc), suppression of locomotor activity and sleep. Each response is triggered by light, endures for a relatively fixed interval and does not require additional light for expression. The present studies address the ability of the psychostimulant drugs, methamphetamine (MA), modafinil (MOD) or caffeine (CAF), to modify the light-induced responses. Drug or vehicle (VEH) was injected at CT11 into constant dark-housed mice then exposed to 5-min 100μW/cm(2) light or no light at CT13. Controls (VEH/Light) showed approximately 60-min phase delays. In contrast, response was substantially attenuated by each drug (only 12-15min delays). Under a 12-h light:12-h dark (LD12:12) photoperiod, VEH/light-treated mice experienced a Tc drop of about 1.3°C coincident with locomotor suppression and both effects were abolished by drug pre-treatment. Each drug elevated activity during the post-injection interval, but there was also evidence for CAF-induced hypoactivity in the dark prior to the photic test stimulus. CAF acutely elevated Tc; MA acutely lowered it, but both drugs reduced Tc during the early dark (ZT12.5-ZT13). The ability of the psychostimulant drugs to block the several effects of light exposure is not the result of drug-induced hyperactivity. The results raise questions concerning the manner in which drugs, activity, sleep and Tc influence behavioral and physiological responses to light.
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Affiliation(s)
- P Vivanco
- Department of Psychiatry, Health Science Center, Stony Brook University, Stony Brook, NY, United States
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18
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Saderi N, Cazarez-Márquez F, Buijs FN, Salgado-Delgado RC, Guzman-Ruiz MA, del Carmen Basualdo M, Escobar C, Buijs RM. The NPY intergeniculate leaflet projections to the suprachiasmatic nucleus transmit metabolic conditions. Neuroscience 2013; 246:291-300. [PMID: 23680526 DOI: 10.1016/j.neuroscience.2013.05.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 05/02/2013] [Accepted: 05/03/2013] [Indexed: 11/27/2022]
Abstract
The intergeniculate leaflet (IGL) is classically known as the area of the Thalamic Lateral Geniculate Complex providing the suprachiasmatic nucleus (SCN) non-photic information. In the present study we investigated whether this information might be related to the metabolic state of the animal. The following groups of male Wistar rats were used for analysis of neuropeptide Y (NPY) and c-Fos in the IGL and SCN. (1) Fed ad libitum. (2) Fasted for 48 h. (3) Fasted for 48 h followed by refeeding for 3 h. (4) Monosodium glutamate-lesioned and 48 h fasted. (5) Electrolytic lesion in the IGL and 48 h fasted. The results were quantified by optical densitometry. Neuronal tracers were injected in two brain areas that receive metabolic information from the periphery, the arcuate nucleus (ARC) and Nucleus of the Tractus Solitarius to investigate whether there is an anatomical relationship with the IGL. Lesion studies showed the IGL, and not the ARC, as origin of most NPY projections to the SCN. Fasting induced important changes in the NPY expression in the IGL, coinciding with similar changes of NPY/glutamate decarboxylase projections of the IGL to the SCN. These changes revealed that the IGL is involved in the transmission of metabolic information to the SCN. In fasted animals IGL lesion resulted in a significant increase of c-Fos in the SCN as compared to intact fasted animals demonstrating the inhibitory influence of the IGL to the SCN in fasting conditions. When the animal after fasting was refed, an increase of c-Fos in the SCN indicated a removal of this inhibitory input. Together these observations show that in addition to increased inhibitory IGL input during fasting, the negative metabolic condition also results in increased excitatory input to the SCN via other pathways. Consequently the present observations show that at least part of the non-photic input to the SCN, arising from the IGL contains information about metabolic conditions.
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Affiliation(s)
- N Saderi
- Laboratory of Hypothalamic Integration Mechanism, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Apartado Postal 70228, Ciudad Universitaria, 04510 Mexico DF, Mexico
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19
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Abstract
Investigators typically study one function of the circadian visual system at a time, be it photoreception, transmission of photic information to the suprachiasmatic nucleus (SCN), light control of rhythm phase, locomotor activity, or gene expression. There are good reasons for such a focused approach, but sometimes it is advantageous to look at the broader picture, asking how all the parts and functions complete the whole. Here, several seemingly disparate functions of the circadian visual system are examined. They share common characteristics with respect to regulation by light and, to the extent known, share a common input neuroanatomy. The argument presented is that the 3 hypothalamically mediated effects of light for which there are the most data, circadian clock phase shifts, suppression of nocturnal locomotion (“negative masking”), and suppression of nocturnal pineal function, are regulated by a common photic input pathway terminating in the SCN. For each, light triggers a relatively fixed interval response that is irradiance-dependent, the effective stimulus can be very brief light exposure, and the response continues to completion in the absence of additional light. The presence of a triggered, fixed-length response interval is of particular importance to the understanding of the circuitry and mechanisms regulating circadian rhythm phase shifts because it implies that the SCN clock response to light is not instantaneous. It also may explain why certain stimuli (neuropeptide Y or novel wheel running) administered many minutes after light exposure are able to block light-induced phase shifts. The understanding of negative masking is complicated by the fact that it can be represented as a positive change, that is, light-induced sleep, not just as a reduction in locomotion. Acute nocturnal light exposure also induces adrenal hormone secretion and a rapid drop in body temperature, physiological responses that appear to be regulated similarly to the other light effects. The likelihood of a common regulatory basis for the several responses suggests that additional light-induced responses will be forthcoming and raises questions about the relationships between light, SCN cellular anatomy, the molecular clockworks of SCN neurons, and SCN throughput mechanisms for regulating disparate downstream activities.
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Affiliation(s)
- Lawrence P. Morin
- Department of Psychiatry, Stony Brook Medical Center, Stony Brook University, Stony Brook, NY
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20
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Blasiak A, Blasiak T, Lewandowski MH, Hossain MA, Wade JD, Gundlach AL. Relaxin-3 innervation of the intergeniculate leaflet of the rat thalamus - neuronal tract-tracing and in vitro electrophysiological studies. Eur J Neurosci 2013; 37:1284-94. [PMID: 23432696 DOI: 10.1111/ejn.12155] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 01/16/2013] [Indexed: 11/29/2022]
Abstract
Behavioural state is controlled by a range of neural systems that are sensitive to internal and external stimuli. The relaxin-3 and relaxin family peptide receptor 3 (RXFP3) system has emerged as a putative ascending arousal network with putative involvement in regulation of stress responses, neuroendocrine control, feeding and metabolism, circadian activity and cognition. Relaxin-3/γ-aminobutyric acid neuron populations have been identified in the nucleus incertus, pontine raphe nucleus, periaqueductal grey (PAG) and an area dorsal to the substantia nigra. Relaxin-3-positive fibres/terminals densely innervate arousal-related structures in the brainstem, hypothalamus and limbic forebrain, but the functional significance of the heterogeneous relaxin-3 neuron distribution and its inputs to specific brain areas are unclear. Therefore, in this study, we used neuronal tract-tracing and immunofluorescence staining to explore the source of the dense relaxin-3 innervation of the intergeniculate leaflet (IGL) of the thalamus, a component of the neural circadian timing system. Confocal microscopy analysis revealed that relaxin-3-positive neurons retrogradely labelled from the IGL were predominantly present in the PAG and these neurons expressed corticotropin-releasing factor receptor-like immunoreactivity. Subsequently, whole-cell patch-clamp recordings revealed heterogeneous effects of RXFP3 activation in the IGL by the RXFP3 agonist, relaxin-3 B-chain/insulin-like peptide-5 A-chain (R3/I5). Identified, neuropeptide Y-positive IGL neurons, known to influence suprachiasmatic nucleus activity, were excited by R3/I5, whereas neurons of unidentified neurotransmitter content were either depolarized or displayed a decrease in action potential firing and/or membrane potential hyperpolarization. Our data identify a PAG to IGL relaxin-3/RXFP3 pathway that might convey stress-related information to key elements of the circadian system and influence behavioural state rhythmicity.
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Affiliation(s)
- Anna Blasiak
- Department of Neurophysiology and Chronobiology, Jagiellonian University, Gronostajowa 9, 30-387, Krakow, Poland.
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21
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Studholme KM, Gompf HS, Morin LP. Brief light stimulation during the mouse nocturnal activity phase simultaneously induces a decline in core temperature and locomotor activity followed by EEG-determined sleep. Am J Physiol Regul Integr Comp Physiol 2013; 304:R459-71. [PMID: 23364525 DOI: 10.1152/ajpregu.00460.2012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Light exerts a variety of effects on mammals. Unexpectedly, one of these effects is the cessation of nocturnal locomotion and the induction of behavioral sleep (photosomnolence). Here, we extend the initial observations in several ways, including the fundamental demonstration that core body temperature (T(c)) drops substantially (about 1.5°C) in response to the light stimulation at CT15 or CT18 in a manner suggesting that the change is a direct response to light rather than simply a result of the locomotor suppression. The results show that 1) the decline of locomotion and T(c) begin soon after nocturnal light stimulation; 2) the variability in the magnitude and onset of light-induced locomotor suppression is very large, whereas the variability in T(c) is very small; 3) T(c) recovers from the light-induced decline in advance of the recovery of locomotion; 4) under entrained and freerunning conditions, the daily late afternoon T(c) increase occurs in advance of the corresponding increase in wheel running; and 5) toward the end of the subjective night, the nocturnally elevated T(c) persists longer than does locomotor activity. Finally, EEG measurements confirm light-induced sleep and, when T(c) or locomotion was measured, show their temporal association with sleep onset. Both EEG- and immobility-based sleep detection methods confirm rapid induction of light-induced sleep. The similarities between light-induced loss of locomotion and drop in T(c) suggest a common cause for parallel responses. The photosomnolence response may be contingent upon both the absence of locomotion and a simultaneous low T(c).
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Affiliation(s)
- Keith M Studholme
- Department of Psychiatry, Stony Brook Medical Center, Stony Brook, NY 11794-8101, USA
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22
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Hughes ATL, Piggins HD. Feedback actions of locomotor activity to the circadian clock. PROGRESS IN BRAIN RESEARCH 2012; 199:305-336. [PMID: 22877673 DOI: 10.1016/b978-0-444-59427-3.00018-6] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The phase of the mammalian circadian system can be entrained to a range of environmental stimuli, or zeitgebers, including food availability and light. Further, locomotor activity can act as an entraining signal and represents a mechanism for an endogenous behavior to feedback and influence subsequent circadian function. This process involves a number of nuclei distributed across the brain stem, thalamus, and hypothalamus and ultimately alters SCN electrical and molecular function to induce phase shifts in the master circadian pacemaker. Locomotor activity feedback to the circadian system is effective across both nocturnal and diurnal species, including humans, and has recently been shown to improve circadian function in a mouse model with a weakened circadian system. This raises the possibility that exercise may be useful as a noninvasive treatment in cases of human circadian dysfunction including aging, shift work, transmeridian travel, and the blind.
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Affiliation(s)
- Alun T L Hughes
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom.
| | - Hugh D Piggins
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
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23
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Paulus EV, Mintz EM. Developmental disruption of the serotonin system alters circadian rhythms. Physiol Behav 2012; 105:257-63. [DOI: 10.1016/j.physbeh.2011.08.032] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 08/03/2011] [Accepted: 08/24/2011] [Indexed: 11/28/2022]
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24
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Glass JD, Guinn J, Kaur G, Francl JM. On the intrinsic regulation of neuropeptide Y release in the mammalian suprachiasmatic nucleus circadian clock. Eur J Neurosci 2010; 31:1117-26. [PMID: 20377624 DOI: 10.1111/j.1460-9568.2010.07139.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Timing of the circadian clock of the suprachiasmatic nucleus (SCN) is regulated by photic and non-photic inputs. Of these, neuropeptide Y (NPY) signaling from the intergeniculate leaflet (IGL) to the SCN plays a prominent role. Although NPY is critical to clock regulation, neither the mechanisms modulating IGL NPY neuronal activity nor the nature of regulatory NPY signaling in the SCN clock are understood, as NPY release in the SCN has never been measured. Here, microdialysis procedures for in vivo measurement of NPY were used in complementary experiments to address these questions. First, neuronal release of NPY in the hamster SCN was rhythmic under a 14L : 10D photocycle, with the acrophase soon after lights-on and the nadir at midday. No rhythmic fluctuation in NPY occurred under constant darkness. Second, a behavioral phase-resetting stimulus (wheel-running at midday that induces IGL serotonin release) acutely stimulated SCN NPY release. Third, bilateral IGL microinjection of the serotonin agonist, (+/-)-2-dipropyl-amino-8-hydroxyl-1,2,3,4-tetrahydronapthalene (8-OH-DPAT) (another non-photic phase-resetting stimulant), at midday enhanced SCN NPY release. Conversely, similar application of the serotonin antagonist, metergoline, abolished wheel-running-induced SCN NPY release. IGL microinjection of the GABA agonist, muscimol, suppressed SCN NPY release. These results support an intra-IGL mechanism whereby behavior-induced serotonergic activity suppresses inhibitory GABAergic transmission, promoting NPY activity and subsequent phase resetting. Collectively, these results confirm IGL-mediated NPY release in the SCN and verify that its daily rhythm of release is dependent upon the 14L : 10D photocycle, and that it is modulated by appropriately-timed phase-resetting behavior, probably mediated by serotonergic activation of NPY units in the IGL.
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Affiliation(s)
- J David Glass
- Department of Biological Sciences, Kent State University, Kent, OH 44242-0001, USA.
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25
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Biello SM. Circadian clock resetting in the mouse changes with age. AGE (DORDRECHT, NETHERLANDS) 2009; 31:293-303. [PMID: 19557547 PMCID: PMC2813053 DOI: 10.1007/s11357-009-9102-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Accepted: 06/08/2009] [Indexed: 05/28/2023]
Abstract
The most widely recognised consequence of normal age-related changes in biological timing is the sleep disruption that appears in old age and diminishes the quality of life. These sleep disorders are part of the normal ageing process and consist primarily of increased amounts of wakefulness and reduced amounts of deep sleep. Changes in the amplitude and timing of the sleep-wake cycle appear to represent, at least in part, a loss of effective circadian regulation of sleep. Understanding alterations in the characteristics of stimuli that help to consolidate internal rhythms will lead to recommendations to improve synchronisation in old age. Converging evidence from both human and animal studies indicate that senescence is associated with alterations in the neural structure thought to be primarily responsible for the generation of the circadian oscillation, the suprachiasmatic nuclei (SCN). Work has shown that there are changes in the anatomy, physiology and ability of the clock to reset in response to stimuli with age. Therefore it is possible that at least some of the observed age-related changes in sleep and circadian timing could be mediated at the level of the SCN. The SCN contain a circadian clock whose activity can be recorded in vitro for several days. We have tested the response of the circadian clock to a number of neurochemicals that reset the clock in a manner similar to light, including glutamate, N-methyl-D-aspartate (NMDA), gastrin-releasing peptide (GRP) and histamine (HA). In addition, we have also tested agents which phase shift in a pattern similar to behavioural 'non-photic' signals, including neuropeptide Y (NPY), serotonin (5HT) and gamma-aminobutyric acid (GABA). These were tested on the circadian clock in young and older mice (approximately 4 and 15 months old). We found deficits in the response to specific neurochemicals but not to others in our older mice. These results indicate that some changes seen in the responsiveness of the circadian clock to light with age may be mediated at the level of the SCN. Further, the responsiveness of the circadian clock with age is attenuated to some, but not all stimuli. This suggests that not all clock stimuli lose their effectiveness with age, and that it may be possible to compensate for deficits in clock performance by enhancing the strength of those stimulus pathways which are intact.
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26
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Scherbarth F, Steinlechner S. The Annual Activity Pattern of Djungarian Hamsters (Phodopus sungorus) Is Affected by Wheel‐Running Activity. Chronobiol Int 2009; 25:905-22. [DOI: 10.1080/07420520802544514] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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27
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28
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Novak CM, Ehlen JC, Albers HE. Photic and nonphotic inputs to the diurnal circadian clock. BIOL RHYTHM RES 2008. [DOI: 10.1080/09291010701683482] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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29
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Yi CX, Challet E, Pévet P, Kalsbeek A, Escobar C, Buijs RM. A circulating ghrelin mimetic attenuates light-induced phase delay of mice and light-induced Fos expression in the suprachiasmatic nucleus of rats. Eur J Neurosci 2008; 27:1965-72. [DOI: 10.1111/j.1460-9568.2008.06181.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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30
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Ehlen JC, Novak CM, Karom MC, Gamble KL, Albers HE. Interactions of GABA A receptor activation and light on period mRNA expression in the suprachiasmatic nucleus. J Biol Rhythms 2008; 23:16-25. [PMID: 18258754 DOI: 10.1177/0748730407310785] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Activation of gamma-aminobutyric acid (GABA) A receptors in the suprachiasmatic nucleus (SCN) resets the circadian clock during the day and inhibits the ability of light to reset the clock at night. Light in turn acts during the day to inhibit the phase-resetting effects of GABA. Some evidence suggests that Period mRNA changes in the SCN are responsible for these interactions between light and GABA. Here, the hypothesis that light and the GABA A receptor interact by altering the expression of Period 1 and/or Period 2 mRNA in the SCN is tested. The GABA A agonist muscimol was injected near the SCN just prior to a light pulse, during the mid-subjective day and the early and late subjective night. Changes in Period 1 and Period 2 mRNA were measured in the SCN by in situ hybridization. Light-induced Period 1 mRNA was inhibited by GABA A receptor activation in the early and late subjective night, while Period 2 mRNA was only inhibited during the late night. During the subjective day, light had no effect on the ability of muscimol to suppress Period 1 mRNA hybridization signal. Thus, light and GABA A receptor activation inhibit each other's ability to induce behavioral phase shifts throughout the subjective day and night. However, only in the late night are these behavioral effects correlated with changes in Period gene expression. Together, our data support the hypothesis that the interacting effects of light and GABA are the result of the opposing actions of these stimuli on Period mRNA, but only during the subjective night.
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31
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Acute ethanol modulates glutamatergic and serotonergic phase shifts of the mouse circadian clock in vitro. Neuroscience 2008; 152:837-48. [PMID: 18313227 DOI: 10.1016/j.neuroscience.2007.12.049] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 12/18/2007] [Accepted: 12/28/2007] [Indexed: 01/05/2023]
Abstract
Alcohol abuse is associated with sleep problems, which are often linked to circadian rhythm disturbances. However, there is no information on the direct effects of ethanol on the mammalian circadian clock. Acute ethanol inhibits glutamate signaling, which is the primary mechanism through which light resets the mammalian clock in the suprachiasmatic nucleus (SCN). Glutamate and light also inhibit circadian clock resetting induced by nonphotic signals, including 5-HT. Thus, we investigated the effects of acute ethanol on both glutamatergic and serotoninergic resetting of the mouse SCN clock in vitro. We show that ethanol dose-dependently inhibits glutamate-induced phase shifts and enhances serotonergic phase shifts. The inhibition of glutamate-induced phase shifts is not affected by excess glutamate, glycine or d-serine, but is prevented by excess brain-derived neurotrophic factor (BDNF). BDNF is known to augment glutamate signaling in the SCN and to be necessary for glutamate/light-induced phase shifts. Thus, ethanol may inhibit glutamate-induced clock resetting at least in part by blocking BDNF enhancement of glutamate signaling. Ethanol enhancement of serotonergic phase shifts is mimicked by treatments that suppress glutamate signaling in the SCN, including antagonists of glutamate receptors, BDNF signaling and nitric oxide synthase. The combined effect of ethanol with these treatments is not additive, suggesting they act through a common pathway. Our data indicate further that the interaction between 5-HT and glutamate in the SCN may occur downstream from nitric oxide synthase activation. Thus, acute ethanol disrupts normal circadian clock phase regulation, which could contribute to the physiological and psychological problems associated with alcohol abuse.
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32
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Mrosovsky N. A non-photic gateway to the circadian clock of hamsters. CIBA FOUNDATION SYMPOSIUM 2007; 183:154-67; discussion 167-74. [PMID: 7656684 DOI: 10.1002/9780470514597.ch9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
This paper considers the neural mechanisms underlying a particular kind of non-photic phase shifting, that produced by novelty-induced wheel running in the hamster. The projection from the intergeniculate leaflet (IGL) to the suprachiasmatic nucleus (SCN) appears to be an important part of the mechanism mediating such phase shifts. A number of experiments support this view. First, expression of immediate-early genes in the IGL is induced by non-photic phase-shifting stimuli. Second, Fos-like immunoreactivity in the IGL co-localizes with neuropeptide Y (NPY) immunoreactivity. Third, direct application of NPY to the SCN produces phase shifts which do not depend on the hamsters becoming active following the injections. Fourth, blocking the normal actions of NPY at the SCN blocks or greatly attenuates the phase shifting that is normally produced by novelty-induced wheel running. Progress on the physiological basis of phase shifts associated with activity, or a correlate, depends on understanding the behavioural aspects of this phenomenon. The activity-shift response curve is especially useful.
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Affiliation(s)
- N Mrosovsky
- Department of Zoology, University of Toronto, Ontario, Canada
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Maywood ES, Mrosovsky N. A molecular explanation of interactions between photic and non-photic circadian clock-resetting stimuli. Gene Expr Patterns 2007; 1:27-31. [PMID: 15018816 DOI: 10.1016/s1567-133x(01)00005-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2001] [Indexed: 11/28/2022]
Abstract
Non-photic clock-resetting events (arousal and locomotor activity) in the subjective day reduced expression of Period genes in the suprachiasmatic nucleus of hamsters. This decrease was attenuated by a 30-min light pulse occurring during the last 0.5 h of 3.5 h of confinement to a novel running wheel. This provides an example at the molecular level of an interaction between different modalities of synchronizing agents.
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Affiliation(s)
- E S Maywood
- Department of Anatomy, University of Cambridge, Cambridge CB2 3DY, UK
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34
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Weinert D, Weinandy R, Gattermann R. Photic and non-photic effects on the daily activity pattern of Mongolian gerbils. Physiol Behav 2007; 90:325-33. [PMID: 17084868 DOI: 10.1016/j.physbeh.2006.09.019] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2006] [Revised: 09/18/2006] [Accepted: 09/20/2006] [Indexed: 11/16/2022]
Abstract
The paper analyses the daily activity pattern of Mongolian gerbils with and without access to a running wheel. To evaluate the synchronizing and the masking effects of light, experiments were performed under different photoperiods (L:D=14:10 h and 10:14 h), and light and dark pulses were applied at different phases of the day-night cycle. In order to get a more direct estimate of the central pacemaker of the circadian system, the body temperature rhythm was investigated via implanted transmitters. Without access to a running wheel, the daily activity pattern was bimodal. One peak occurred in the first half of the light time, the other one around the light-dark transition. Also, the gerbils were more active during the light phase as compared to the dark phase. After unlocking the running wheel, the gerbils were active mainly during the dark time. The activity peak in the first half of the light phase remained, the second one shifted by a phase delay into the dark time. These results were found under both LD-regimens. Light during the night nearly completely suppressed running wheel activity, switching off the light during the day time induced wheel running. Whereas wheel running was clearly affected by light and dark pulses, the general activity was not. The body temperature rhythm also shows two peaks, with the second one being bigger and coinciding with the endogenous component of the circadian body temperature rhythm. It was found around light-off. After unlocking the running wheel, the maximum of the body temperature rhythm shifted to the night. This was not primarily a consequence of the changed activity pattern as shown by means of purification analysis. Removing the direct effects of motor activity led to a body temperature curve that could be described by a cosine function, and the delay shift was found also for the purified data, a better estimate of the endogenous circadian component. The wheel-associated increase in nocturnality is not only due to masking effects of wheel-running activity on the body temperature and activity rhythms. It also involves clock-related processes. Changes in the phase preference may serve as an adaptation mechanism to the changes in the animal's natural environment.
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Affiliation(s)
- D Weinert
- Institute of Zoology, Martin-Luther-University Halle-Wittenberg, Domplatz 4, D-06108 Halle, Germany.
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35
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Gamble KL, Paul KN, Karom MC, Tosini G, Albers HE. Paradoxical effects of NPY in the suprachiasmatic nucleus. Eur J Neurosci 2006; 23:2488-94. [PMID: 16706855 DOI: 10.1111/j.1460-9568.2006.04784.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The circadian clock in the suprachiasmatic nucleus (SCN) is synchronized by the 24 h, light : dark cycle, and is reset by photic and non-photic cues. The acute effects of light in the SCN include the increase of mRNA levels of the circadian clock gene Per1 and a dramatic reduction of pineal melatonin. Neuropeptide Y (NPY), which appears to mediate the phase-resetting effects of non-photic stimuli, prevents the ability of light, and stimuli that mimic light, to phase shift the circadian clock when injected into the SCN. The purpose of the present study was to determine if NPY inhibits the ability of light to suppress pineal melatonin. Surprisingly, NPY injected into the SCN of hamsters mimicked the effects of light by suppressing pineal melatonin levels. To confirm that NPY inhibited the effects of light on the induction of Per1 mRNA levels, Per1 mRNA levels in the SCN were measured in these same animals. NPY significantly reduced Per1 mRNA levels induced by the light pulse. The suppression of melatonin by NPY appears to be mediated by the same subtype of NPY receptors in the SCN that mediate the modulation of phase shifts. Injection of Y5 receptor agonists mimicked the effects of NPY on pineal melatonin, while injection of a Y2 agonist did not. Thus, these data are the first to demonstrate the paradoxical effects of NPY within the SCN. NPY mimics the effects of light on pineal melatonin and inhibits the effects of light on the induction of Per1 mRNA.
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Affiliation(s)
- Karen L Gamble
- Department of Psychology, Georgia State University, Atlanta, GA, USA
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36
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Morin LP, Allen CN. The circadian visual system, 2005. ACTA ACUST UNITED AC 2006; 51:1-60. [PMID: 16337005 DOI: 10.1016/j.brainresrev.2005.08.003] [Citation(s) in RCA: 306] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2005] [Revised: 07/19/2005] [Accepted: 08/09/2005] [Indexed: 11/17/2022]
Abstract
The primary mammalian circadian clock resides in the suprachiasmatic nucleus (SCN), a recipient of dense retinohypothalamic innervation. In its most basic form, the circadian rhythm system is part of the greater visual system. A secondary component of the circadian visual system is the retinorecipient intergeniculate leaflet (IGL) which has connections to many parts of the brain, including efferents converging on targets of the SCN. The IGL also provides a major input to the SCN, with a third major SCN afferent projection arriving from the median raphe nucleus. The last decade has seen a blossoming of research into the anatomy and function of the visual, geniculohypothalamic and midbrain serotonergic systems modulating circadian rhythmicity in a variety of species. There has also been a substantial and simultaneous elaboration of knowledge about the intrinsic structure of the SCN. Many of the developments have been driven by molecular biological investigation of the circadian clock and the molecular tools are enabling novel understanding of regional function within the SCN. The present discussion is an extension of the material covered by the 1994 review, "The Circadian Visual System."
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Affiliation(s)
- L P Morin
- Department of Psychiatry and Graduate Program in Neuroscience, Stony Brook University, Stony Brook, NY 11794, USA.
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37
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Abstract
Living organisms are endowed with an autonomous timekeeping program that not only maintains circadian rhythms of behaviour and physiology but is reset by cues from the external, cyclic environment. Intracellular signaling events that mediate entrainment of the mammalian circadian clock by photic (light) as well as non-photic inputs are only beginning to be elucidated. Dexras1 is a novel Ras-like G protein that modulates multiple signaling cascades. Genetic ablation of Dexras1 in mice (dexras1(-/-)) results in altered responsiveness of the master circadian clock to photic and non-photic cues. This review will attempt to provide mechanistic insights into the involvement of Dexras1 in biological timing processes based on its role as a modulator of signal transduction.
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Affiliation(s)
- Hai-Ying Mary Cheng
- Department of Medical Biophysics, The University Health Network, University of Toronto, 610 University Avenue, Toronto, Ont., Canada M5G 2M9.
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38
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Webb IC, Pollock MS, Mistlberger RE. Modafinil [2-[(Diphenylmethyl)sulfinyl]acetamide] and Circadian Rhythms in Syrian Hamsters: Assessment of the Chronobiotic Potential of a Novel Alerting Compound. J Pharmacol Exp Ther 2006; 317:882-9. [PMID: 16461586 DOI: 10.1124/jpet.105.099010] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In Syrian hamsters, behavioral procedures for inducing arousal (e.g., running in a novel wheel or gentle handling) can shift circadian rhythms when applied during the usual sleep period ("subjective day") and can attenuate phase shifts to light during the active period ("subjective night"). This raises the possibility that drugs that affect behavioral state may have "chronobiotic" potential. We characterized the effects of modafinil (2-[(diphenylmethyl)sulfinyl]acetamide), an atypical alerting compound, on circadian rhythms in male Syrian hamsters. Electroencephalogram recordings and video observations confirmed that modafinil dose dependently increases wakefulness at the expense of slow-wave and paradoxical sleep with no increase in locomotor activity per unit of time awake. Despite inducing arousal, modafinil at these doses (150 or 300 mg/kg), administered in the subjective day or early or late in the subjective night, did not perturb circadian phase. Modafinil (300 mg/kg) also had no effect on phase shifts to light exposure either early or late in the night and did not alter the size of phase shifts induced by running in a novel wheel for 3 h during the mid-day. Modafinil (300 mg/kg) did, however, decrease by approximately 50% the amount of novel wheel-stimulated running, moving leftward the dose-response relation between wheel revolutions and shift magnitude. These results indicate that, in Syrian hamsters, modafinil alone has no significant chronobiotic efficacy. Nevertheless, this agent may increase the sensitivity of the circadian pacemaker to nonphotic stimuli and may thus have some potential as a tool for promoting clock resetting in combination with behavioral strategies.
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Affiliation(s)
- Ian C Webb
- Department of Psychology, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
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39
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Duncan MJ, Franklin KM, Davis VA, Grossman GH, Knoch ME, Glass JD. Short-term constant light potentiation of large-magnitude circadian phase shifts induced by 8-OH-DPAT: effects on serotonin receptors and gene expression in the hamster suprachiasmatic nucleus. Eur J Neurosci 2005; 22:2306-14. [PMID: 16262668 DOI: 10.1111/j.1460-9568.2005.04399.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nonphotic phase-shifting of mammalian circadian rhythms is thought to be mediated in part by serotonin (5-HT) acting in the suprachiasmatic nucleus (SCN) circadian clock. Previously we showed that brief (1-3 days) exposure to constant light (LL) greatly potentiates nonphotic phase-shifting induced by the 5-HT agonist, (+/-)2-dipropyl-amino-8-hydroxyl-1,2,3,4-tetrahydronapthalene (8-OH-DPAT). Here we investigated potential mechanisms for this action of LL, including 5-HT receptor upregulation and SCN clock gene and neuropeptide gene expression. Autoradiographic analysis of ritanserin inhibition of [3H]8-OH-DPAT binding indicated that LL (approximately 2 days) did not affect 5-HT7 receptor binding in the SCN or dorsal raphe. Measurement of 5-HT1A autoreceptors in the median raphe and 5-HT1B receptors in the SCN also showed no effect of LL. In experiment 2, hamsters held under a 14-h light : 10-h dark photocycle (LD) or exposed to LL for approximately 2 days received an intraperitoneal injection of 8-OH-DPAT or vehicle at zeitgeber time (ZT) 6 or 0 and were killed after 2 h of dark exposure. 8-OH-DPAT suppressed SCN Per1 and Per2 mRNAs at both ZTs, as assessed by in situ hybridization. Per1 mRNA was also suppressed by LL alone. In addition, in situ hybridization of arginine vasopressin (AVP) mRNA and vasoactive intestinal polypeptide mRNA showed that LL significantly suppressed the former but not the latter. The LL-induced suppression of SCN Per1 mRNA and AVP mRNA may be involved in LL-induced potentiation of pacemaker resetting, especially as these data provide additional evidence that LL suppresses circadian pacemaker amplitude, thus rendering the clock more susceptible to phase-shifting stimuli.
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Affiliation(s)
- Marilyn J Duncan
- Department of Anatomy and Neurobiology, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536, USA.
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40
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Landry GJ, Mistlberger RE. Differential effects of constant light on circadian clock resetting by photic and nonphotic stimuli in Syrian hamsters. Brain Res 2005; 1059:52-8. [PMID: 16169532 DOI: 10.1016/j.brainres.2005.08.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2005] [Revised: 08/09/2005] [Accepted: 08/09/2005] [Indexed: 11/29/2022]
Abstract
Circadian rhythms in Syrian hamsters can be phase shifted by behavioral arousal during the usual rest phase of the circadian rest-activity cycle. Phase shifts can be greatly potentiated by exposing the animals to constant light for 1 or 2 cycles. This could reflect a change in a specific nonphotic input pathway to the suprachiasmatic nucleus (SCN) circadian pacemaker, or it could be caused by a change in the amplitude of the pacemaker. If the latter, then phase shifts to any stimulus, including those activating the photic input pathway, should be potentiated. This hypothesis was tested by measuring phase shifts induced by microinjections of NMDA (500 nl, 10 mM) into the SCN area of hamsters exposed to constant light or dark for 2 days. NMDA induced significant phase delay shifts that mimicked those induced by light exposure early in the night. The magnitude of these shifts did not differ by prior lighting condition. Shifts induced by NMDA (200 nl, 10 mM) microinjections on day 3 and 13 of LL also did not differ. Phase shifts induced by a nonphotic stimulus (3 h of running stimulated by confinement to a novel wheel) were significantly potentiated by 2 days of exposure to constant light. These results indicate that exposure to constant light for 2 circadian cycles differentially affects phase resetting responses to photic and nonphotic inputs to the circadian pacemaker, suggesting that potentiation of shifts to nonphotic stimuli reflect changes in a nonphotic input pathway rather than in an amplitude dimension of the circadian pacemaker.
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Affiliation(s)
- Glenn J Landry
- Department of Psychology, Simon Fraser University, 8888 University Drive, Burnaby BC, Canada V5A 1S6
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41
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Gamble KL, Ehlen JC, Albers HE. Circadian control during the day and night: Role of neuropeptide Y Y5 receptors in the suprachiasmatic nucleus. Brain Res Bull 2005; 65:513-9. [PMID: 15862923 DOI: 10.1016/j.brainresbull.2005.03.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2004] [Revised: 01/20/2005] [Accepted: 03/01/2005] [Indexed: 11/24/2022]
Abstract
Circadian rhythms are reset by light during the night or by nonphotic stimuli during the day. Neuropeptide Y (NPY), which appears to mediate at least some nonphotic phase shifts by its actions in the suprachiasmatic nucleus (SCN), induces phase advances during the day and inhibits light-induced phase advances during the night. In this study, we used a highly selective Y5-like agonist to test whether activation of NPY Y5 receptors is sufficient to mimic NPY during the day and late night in Syrian hamsters. We also tested whether NPY in the early night reduces light-induced phase delays in a dose-dependent manner. Microinjection of a selective Y5 receptor agonist, (Ala(31), Aib(32))-NPY, into the SCN significantly inhibited light-induced phase advances during the late night, but did not induce phase advances during the day. In addition, concentrations of NPY ranging from 0.23 to 23 mM did not attenuate light-induced phase delays in the early night. These results suggest that activation of Y5-like receptors is sufficient to inhibit light-induced phase advances during the late night but is not sufficient to induce phase advances during the day. Furthermore, this study provided no evidence that NPY can inhibit light-induced phase shifts early in the night.
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Affiliation(s)
- Karen L Gamble
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
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42
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Mendoza J, Graff C, Dardente H, Pevet P, Challet E. Feeding cues alter clock gene oscillations and photic responses in the suprachiasmatic nuclei of mice exposed to a light/dark cycle. J Neurosci 2005; 25:1514-22. [PMID: 15703405 PMCID: PMC6725981 DOI: 10.1523/jneurosci.4397-04.2005] [Citation(s) in RCA: 164] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2004] [Revised: 12/14/2004] [Accepted: 12/25/2004] [Indexed: 11/21/2022] Open
Abstract
The suprachiasmatic nuclei (SCN) of the hypothalamus contain the master mammalian circadian clock, which is mainly reset by light. Temporal restricted feeding, a potent synchronizer of peripheral oscillators, has only weak influence on light-entrained rhythms via the SCN, unless restricted feeding is coupled with calorie restriction, thereby altering phase angle of photic synchronization. Effects of daytime restricted feeding were investigated on the mouse circadian system. Normocaloric feeding at midday led to a predominantly diurnal (60%) food intake and decreased blood glucose in the afternoon, but it did not affect the phase of locomotor activity rhythm or vasopressin expression in the SCN. In contrast, hypocaloric feeding at midday led to 2-4 h phase advances of three circadian outputs, locomotor activity rhythm, pineal melatonin, and vasopressin mRNA cycle in the SCN, and it decreased daily levels of blood glucose. Furthermore, Per1 and Cry2 oscillations in the SCN were phase advanced by 1 and 3 h, respectively, in hypocalorie- but not in normocalorie-fed mice. The phase of Per2 and Bmal1 expression remained unchanged regardless of feeding condition. Moreover, the shape of behavioral phase-response curve to light and light-induced expression of Per1 in the SCN were markedly modified in hypocalorie-fed mice compared with animals fed ad libitum. The present study shows that diurnal hypocaloric feeding affects not only the temporal organization of the SCN clockwork and circadian outputs in mice under light/dark cycle but also photic responses of the circadian system, thus indicating that energy metabolism modulates circadian rhythmicity and gating of photic inputs in mammals.
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Affiliation(s)
- Jorge Mendoza
- Laboratory of Neurobiology of Rhythms, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7518, Department of Neuroscience, Institut Fédératif de Recherche 37, University Louis Pasteur, F-67084 Strasbourg, France
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43
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Soscia SJ, Harrington ME. Neuropeptide Y attenuates NMDA-induced phase shifts in the SCN of NPY Y1 receptor knockout mice in vitro. Brain Res 2004; 1023:148-53. [PMID: 15364030 DOI: 10.1016/j.brainres.2004.07.037] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/14/2004] [Indexed: 11/26/2022]
Abstract
Neuropeptide Y (NPY) blocks the effect of light on the mammalian circadian clock during the subjective night. The present study explores the role of the NPY Y1 receptor in this interaction. The effect of NPY when co-applied with NMDA, a glutamate agonist that can mimic the effect of light, was examined in NPY Y1-/- mice (background strain 129SVXBalb/c) using electrophysiology. Cells in the suprachiasmatic nucleus (SCN), the master circadian pacemaker, show a circadian rhythm in spontaneous firing rate that can be recorded in vitro. The results demonstrated that NPY attenuated the phase shifts to NMDA in both the Y1-/- mice and control mice, indicating that the Y1 receptor does not mediate the NPY blockade of photic-like phase shifts. The peak in frequency in the untreated control brain slices from Y1-/- mice was advanced by approximately 1 h as compared to the Y1+/+ mice. The Y1 receptor may contribute to a functional model of circadian rhythms, but apparently is not essential for the effects of NPY on photic phase shifts.
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Affiliation(s)
- Stephanie J Soscia
- Department of Psychology and the Neuroscience Program, Smith College, 417 Bass Hall, Northampton, MA 01063, USA
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44
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Yannielli P, Harrington ME. Let there be “more” light: enhancement of light actions on the circadian system through non-photic pathways. Prog Neurobiol 2004; 74:59-76. [PMID: 15381317 DOI: 10.1016/j.pneurobio.2004.06.001] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2004] [Accepted: 06/18/2004] [Indexed: 11/19/2022]
Abstract
Circadian rhythms are internally generated circa 24 h rhythms. The phase of the circadian pacemaker in mammals can be adjusted by external stimuli such as the daily cycle of light, as well as by internal stimuli such as information related to the physiological and behavioral status of the organism, collectively called "non-photic stimuli". We review a large number of studies regarding photic-non-photic interactions on the circadian system, with special focus on two widely described neurotransmitters associated with non-photic input pathways: neuropeptide Y (NPY) and serotonin 5-HT. Both neurotransmitters are capable of phase advancing the master pacemaker oscillation when applied during the subjective day, as do several behavioral manipulations. Also, both are capable of inhibiting light-induced phase shifts during the subjective night, suggesting a dynamic interaction between photic and non-photic stimuli in the fine-tuning of the pacemaker function. Suppression of the NPYergic and/or serotonergic non-photic input pathways can in turn potentiate the phase-shifting effects of light. These findings pose new questions about the possibility of a physiological role for the dynamic interaction between photic and non-photic inputs. This might be particularly important in the case of circadian system adjustments under certain conditions, such as depression, shift work or jet lag.
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Affiliation(s)
- P Yannielli
- Neuroscience Program, Department of Psychology, Smith College, Northampton, MA 01063, USA
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45
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Cheng HYM, Obrietan K, Cain SW, Lee BY, Agostino PV, Joza NA, Harrington ME, Ralph MR, Penninger JM. Dexras1 Potentiates Photic and Suppresses Nonphotic Responses of the Circadian Clock. Neuron 2004; 43:715-28. [PMID: 15339652 DOI: 10.1016/j.neuron.2004.08.021] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2004] [Revised: 04/01/2004] [Accepted: 08/10/2004] [Indexed: 10/25/2022]
Abstract
Circadian rhythms of physiology and behavior are generated by biological clocks that are synchronized to the cyclic environment by photic or nonphotic cues. The interactions and integration of various entrainment pathways to the clock are poorly understood. Here, we show that the Ras-like G protein Dexras1 is a critical modulator of the responsiveness of the master clock to photic and nonphotic inputs. Genetic deletion of Dexras1 reduces photic entrainment by eliminating a pertussis-sensitive circadian response to NMDA. Mechanistically, Dexras1 couples NMDA and light input to Gi/o and ERK activation. In addition, the mutation greatly potentiates nonphotic responses to neuropeptide Y and unmasks a nonphotic response to arousal. Thus, Dexras1 modulates the responses of the master clock to photic and nonphotic stimuli in opposite directions. These results identify a signaling molecule that serves as a differential modulator of the gated photic and nonphotic input pathways to the circadian timekeeping system.
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Affiliation(s)
- Hai-Ying M Cheng
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohr Gasse 3-5, A-1030 Vienna.
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46
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Mistlberger RE, Skene DJ. Social influences on mammalian circadian rhythms: animal and human studies. Biol Rev Camb Philos Soc 2004; 79:533-56. [PMID: 15366762 DOI: 10.1017/s1464793103006353] [Citation(s) in RCA: 243] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
While light is considered the dominant stimulus for entraining (synchronizing) mammalian circadian rhythms to local environmental time, social stimuli are also widely cited as 'zeitgebers' (time-cues). This review critically assesses the evidence for social influences on mammalian circadian rhythms, and possible mechanisms of action. Social stimuli may affect circadian behavioural programmes by regulating the phase and period of circadian clocks (i.e. a zeitgeber action, either direct or by conditioning to photic zeitgebers), by influencing daily patterns of light exposure or modulating light input to the clock, or by associative learning processes that utilize circadian time as a discriminative or conditioned stimulus. There is good evidence that social stimuli can act as zeitgebers. In several species maternal signals are the primary zeitgeber in utero and prior to weaning. Adults of some species can also be phase shifted or entrained by single or periodic social interactions, but these effects are often weak, and appear to be mediated by social stimulation of arousal. There is no strong evidence yet for sensory-specific nonphotic inputs to the clock. The circadian phase-dependence of clock resetting to social stimuli or arousal (the 'nonphotic' phase response curve, PRC), where known, is distinct from that to light and similar in diurnal and nocturnal animals. There is some evidence that induction of arousal can modulate light input to the clock, but no studies yet of whether social stimuli can shift the clock by conditioning to photic cues, or be incorporated into the circadian programme by associative learning. In humans, social zeitgebers appear weak by comparison with light. In temporal isolation or under weak light-dark cycles, humans may ignore social cues and free-run independently, although cases of mutual synchrony among two or more group-housed individuals have been reported. Social cues may affect circadian timing by controlling sleep-wake states, but the phase of entrainment observed to fixed sleep-wake schedules in dim light is consistent with photic mediation (scheduled variations in behavioural state necessarily create daily light-dark cycles unless subjects are housed in constant dark or have no eyes). By contrast, discrete exercise sessions can induce phase shifts consistent with the nonphotic PRC observed in animal studies. The best evidence for social entrainment in humans is from a few totally blind subjects who synchronize to the 24 h day, or to near-24 h sleep-wake schedules under laboratory conditions. However, the critical entraining stimuli have not yet been identified, and there are no reported cases yet of social entrainment in bilaterally enucleated blind subjects. The role of social zeitgebers in mammalian behavioural ecology, their mechanisms of action, and their utility for manipulating circadian rhythms in humans, remains to be more fully elaborated.
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Affiliation(s)
- Ralph E Mistlberger
- Department of Psychology, Simon Fraser University, Burnaby, BC, Canada V5A 1S6.
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47
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Novak CM, Albers HE. Circadian Phase Alteration by GABA and Light Differs in Diurnal and Nocturnal Rodents During the Day. Behav Neurosci 2004; 118:498-504. [PMID: 15174927 DOI: 10.1037/0735-7044.118.3.498] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
These studies investigated the circadian effects of light and gamma aminobutyric acid-A (GABAA) receptor activation in the suprachiasmatic nucleus (SCN) of the diurnal unstriped Nile grass rat (Arvicanthis niloticus). Microinjection of the GABAA agonist muscimol into the SCN during the day produced phase shifts that were opposite in direction to those previously reported in nocturnal rodents. In addition, light had no significant effect on the magnitude of muscimol-induced phase delays during the daytime. Injection of muscimol during the night, however, significantly inhibited light-induced phase delays and advances in a manner similar to that previously reported in nocturnal rodents. Therefore, the circadian effects of GABAA receptor activation are similar in diurnal and nocturnal species during the night but differ significantly during the day.
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Affiliation(s)
- Colleen M Novak
- Departments of Biology and Psychology, Center for Behavioral Neuroscience, PO Box 4010, Georgia State University, Atlanta, GA 30302-4010, USA.
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48
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Gamble KL, Novak CM, Albers HE. Neuropeptide y and n-methyl-d-aspartic acid interact within the suprachiasmatic nuclei to alter circadian phase. Neuroscience 2004; 126:559-65. [PMID: 15183505 DOI: 10.1016/j.neuroscience.2004.04.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/24/2004] [Indexed: 11/29/2022]
Abstract
Circadian rhythms are reset by exposure to photic stimuli and nonphotic stimuli. Glutamate appears to be the primary neurotransmitter that communicates photic stimuli to the circadian clock located in the suprachiasmatic nucleus. There is also substantial evidence that neuropeptide Y (NPY) mediates the effects of at least some nonphotic stimuli on the circadian clock. The purpose of this study was to investigate how NPY and glutamate receptor activation interact to reset the phase of the circadian clock. Microinjection of the glutamate agonist N-methyl-D-aspartic acid (NMDA) during the subjective day significantly decreased NPY-induced phase advances. During the late subjective night, NMDA induced light-like phase advances, which were significantly reduced by microinjection of NPY. Microinjection of NPY inhibited NMDA-induced phase advances during the late subjective night, even when sodium-dependent action potentials were inhibited by tetrodotoxin. These data support the hypothesis that, during the subjective night, NPY and NMDA act on the same clock cells or on cells that communicate with clock cells by mechanisms not requiring action potentials. Although NPY and NMDA appear to be mutually inhibitory during both the day and the night, the mechanisms of this inhibition appear to be different during the day versus the night.
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Affiliation(s)
- K L Gamble
- Department of Psychology, University Plaza, Georgia State University, Atlanta, GA 30303, USA
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Kronfeld-Schor N, Dayan T. Partitioning of Time as an Ecological Resource. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2003. [DOI: 10.1146/annurev.ecolsys.34.011802.132435] [Citation(s) in RCA: 556] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Tamar Dayan
- Department of Zoology, Tel Aviv University, Tel Aviv 69978, Israel;
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Edelstein K, de la Iglesia HO, Schwartz WJ, Mrosovsky N. Behavioral arousal blocks light-induced phase advances in locomotor rhythmicity but not light-induced Per1 and Fos expression in the hamster suprachiasmatic nucleus. Neuroscience 2003; 118:253-61. [PMID: 12676155 DOI: 10.1016/s0306-4522(02)00908-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Both photic and nonphotic stimuli entrain circadian rhythms. Although the adaptive significance of nonphotic clock resetting is unknown, one possibility is that nonphotic cues modulate circadian responses to light. Results of studies on the interaction between photic and nonphotic stimuli support this idea. During the day, light blocks the effects of nonphotic stimuli on the phase of locomotor rhythms and on expression of clock genes in suprachiasmatic nucleus (SCN) neurons. At night, novelty-induced activity prior to and during exposure to light attenuates the phase-shifting response to that light, but the effects of this manipulation on clock gene expression are unknown. The present experiments explore the interaction between behavioral state and response to light at the molecular level. We show that confining hamsters to novel wheels immediately after a light pulse during the late subjective night attenuates light-induced phase advances of wheel-running rhythms and the transient effects on circadian period. In contrast to the striking effect of novelty-induced activity on behavioral responses to light, Fos protein and Per1 mRNA were robustly expressed in the SCN of all light-pulsed animals, regardless of behavioral treatment. Our results are inconsistent with the idea that light and nonphotic stimuli block each other's effects on phase shifts by inducing or attenuating transcription of Per1. Photic regulation of clock genes and spontaneous rhythmic expression of clock genes are probably mediated by different mechanisms.
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Affiliation(s)
- K Edelstein
- Department of Zoology, University of Toronto, 25 Harbord Street, M5S 3G5, Toronto, Canada.
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