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Costa Petrillo C, Pírez N, Beckwith EJ. Social information as an entrainment cue for the circadian clock. Genet Mol Biol 2024; 47Suppl 1:e20240008. [PMID: 39037375 PMCID: PMC11262420 DOI: 10.1590/1678-4685-gmb-2024-0008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 05/10/2024] [Indexed: 07/23/2024] Open
Abstract
Animals adapt to the daily changes in their environmental conditions by means of genetically encoded circadian clocks. These clocks, found throughout the tree of life, regulate diverse biological functions, and allow periodical changes in physiology and behaviour. The molecular underpinnings of these clocks have been extensively studied across taxa, revealing a brain-based system that coordinates rhythmic activities through neuronal networks and signalling pathways. Entrainment, the alignment of internal rhythms with external cues or zeitgebers, is crucial for the adaptive value of these internal clocks. While the solar light-dark cycle is a primary zeitgeber for most animals, other relevant cues such as temperature, meal timing, predators, anxiety, fear, physical activity, and social interactions also play roles in entraining circadian clocks. The search of a detailed description of the circadian clocks is a goal for neurobiology and an area of growing societal interests. Moreover, as disruptions in circadian rhythms are implicated in various diseases, understanding the entrainment pathways contributes to developing interventions for improved wellbeing and health outcomes. This review focuses on socially relevant cues, examining their impact on animal physiology and behaviour, and explores the sensory pathways transmitting information to the central clock.
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Affiliation(s)
- Chiara Costa Petrillo
- Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Fisiología, Biología Molecular y Neurociencias, Buenos Aires, Argentina
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Instituto de Fisiología, Biología Molecular y Neurociencias, Buenos Aires, Argentina
| | - Nicolás Pírez
- Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Fisiología, Biología Molecular y Neurociencias, Buenos Aires, Argentina
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Instituto de Fisiología, Biología Molecular y Neurociencias, Buenos Aires, Argentina
| | - Esteban J. Beckwith
- Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Fisiología, Biología Molecular y Neurociencias, Buenos Aires, Argentina
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Wang Y, Guo H, He F. Circadian disruption: from mouse models to molecular mechanisms and cancer therapeutic targets. Cancer Metastasis Rev 2023; 42:297-322. [PMID: 36513953 DOI: 10.1007/s10555-022-10072-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 11/25/2022] [Indexed: 12/15/2022]
Abstract
The circadian clock is a timekeeping system for numerous biological rhythms that contribute to the regulation of numerous homeostatic processes in humans. Disruption of circadian rhythms influences physiology and behavior and is associated with adverse health outcomes, especially cancer. However, the underlying molecular mechanisms of circadian disruption-associated cancer initiation and development remain unclear. It is essential to construct good circadian disruption models to uncover and validate the detailed molecular clock framework of circadian disruption in cancer development and progression. Mouse models are the most widely used in circadian studies due to their relatively small size, fast reproduction cycle, easy genome manipulation, and economic practicality. Here, we reviewed the current mouse models of circadian disruption, including suprachiasmatic nuclei destruction, genetic engineering, light disruption, sleep deprivation, and other lifestyle factors in our understanding of the crosstalk between circadian rhythms and oncogenic signaling, as well as the molecular mechanisms of circadian disruption that promotes cancer growth. We focused on the discoveries made with the nocturnal mouse, diurnal human being, and cell culture and provided several circadian rhythm-based cancer therapeutic strategies.
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Affiliation(s)
- Yu Wang
- Academy of Integrative Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China
| | - Haidong Guo
- Academy of Integrative Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
- Department of Anatomy, School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
| | - Feng He
- Academy of Integrative Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
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Jeczmien-Lazur JS, Sanetra AM, Pradel K, Izowit G, Chrobok L, Palus-Chramiec K, Piggins HD, Lewandowski MH. Metabolic cues impact non-oscillatory intergeniculate leaflet and ventral lateral geniculate nucleus: standard versus high-fat diet comparative study. J Physiol 2023; 601:979-1016. [PMID: 36661095 DOI: 10.1113/jp283757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 01/12/2023] [Indexed: 01/21/2023] Open
Abstract
The intergeniculate leaflet and ventral lateral geniculate nucleus (IGL/VLG) are subcortical structures involved in entrainment of the brain's circadian system to photic and non-photic (e.g. metabolic and arousal) cues. Both receive information about environmental light from photoreceptors, exhibit infra-slow oscillations (ISO) in vivo, and connect to the master circadian clock. Although current evidence demonstrates that the IGL/VLG communicate metabolic information and are crucial for entrainment of circadian rhythms to time-restricted feeding, their sensitivity to food intake-related peptides has not been investigated yet. We examined the effect of metabolically relevant peptides on the spontaneous activity of IGL/VLG neurons. Using ex vivo and in vivo electrophysiological recordings as well as in situ hybridisation, we tested potential sensitivity of the IGL/VLG to anorexigenic and orexigenic peptides, such as cholecystokinin, glucagon-like peptide 1, oxyntomodulin, peptide YY, orexin A and ghrelin. We explored neuronal responses to these drugs during day and night, and in standard vs. high-fat diet conditions. We found that IGL/VLG neurons responded to all the substances tested, except peptide YY. Moreover, more neurons responded to anorexigenic drugs at night, while a high-fat diet affected the IGL/VLG sensitivity to orexigenic peptides. Interestingly, ISO neurons responded to light and orexin A, but did not respond to the other food intake-related peptides. In contrast, non-ISO cells were activated by metabolic peptides, with only some being responsive to light. Our results show for the first time that peptides involved in the body's energy homeostasis stimulate the thalamus and suggest functional separation of the IGL/VLG cells. KEY POINTS: The intergeniculate leaflet and ventral lateral geniculate nucleus (IGL/VLG) of the rodent thalamus process various signals and participate in circadian entrainment. In both structures, cells exhibiting infra-slow oscillatory activity as well as non-rhythmically firing neurons being observed. Here, we reveal that only one of these two groups of cells responds to anorexigenic (cholecystokinin, glucagon-like peptide 1 and oxyntomodulin) and orexigenic (ghrelin and orexin A) peptides. Neuronal responses vary depending on the time of day (day vs. night) and on the diet (standard vs. high-fat diet). Additionally, we visualised receptors to the tested peptides in the IGL/VLG using in situ hybridisation. Our results suggest that two electrophysiologically different subpopulations of IGL/VLG neurons are involved in two separate functions: one related to the body's energy homeostasis and one associated with the subcortical visual system.
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Affiliation(s)
- Jagoda S Jeczmien-Lazur
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland
| | - Anna M Sanetra
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland
| | - Kamil Pradel
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland
| | - Gabriela Izowit
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland
| | - Lukasz Chrobok
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland.,School of Physiology, Pharmacology, and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, UK
| | - Katarzyna Palus-Chramiec
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland
| | - Hugh D Piggins
- School of Physiology, Pharmacology, and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, UK
| | - Marian H Lewandowski
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland
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Brock O, Gelegen C, Sully P, Salgarella I, Jager P, Menage L, Mehta I, Jęczmień-Łazur J, Djama D, Strother L, Coculla A, Vernon AC, Brickley S, Holland P, Cooke SF, Delogu A. A Role for Thalamic Projection GABAergic Neurons in Circadian Responses to Light. J Neurosci 2022; 42:9158-9179. [PMID: 36280260 PMCID: PMC9761691 DOI: 10.1523/jneurosci.0112-21.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 09/16/2022] [Accepted: 09/19/2022] [Indexed: 11/07/2022] Open
Abstract
The thalamus is an important hub for sensory information and participates in sensory perception, regulation of attention, arousal and sleep. These functions are executed primarily by glutamatergic thalamocortical neurons that extend axons to the cortex and initiate cortico-thalamocortical connectional loops. However, the thalamus also contains projection GABAergic neurons that do not extend axons toward the cortex. Here, we have harnessed recent insight into the development of the intergeniculate leaflet (IGL) and the ventral lateral geniculate nucleus (LGv) to specifically target and manipulate thalamic projection GABAergic neurons in female and male mice. Our results show that thalamic GABAergic neurons of the IGL and LGv receive retinal input from diverse classes of retinal ganglion cells (RGCs) but not from the M1 intrinsically photosensitive retinal ganglion cell (ipRGC) type. We describe the synergistic role of the photoreceptor melanopsin and the thalamic neurons of the IGL/LGv in circadian entrainment to dim light. We identify a requirement for the thalamic IGL/LGv neurons in the rapid changes in vigilance states associated with circadian light transitions.SIGNIFICANCE STATEMENT The intergeniculate leaflet (IGL) and ventral lateral geniculate nucleus (LGv) are part of the extended circadian system and mediate some nonimage-forming visual functions. Here, we show that each of these structures has a thalamic (dorsal) as well as prethalamic (ventral) developmental origin. We map the retinal input to thalamus-derived cells in the IGL/LGv complex and discover that while RGC input is dominant, this is not likely to originate from M1ipRGCs. We implicate thalamic cells in the IGL/LGv in vigilance state transitions at circadian light changes and in overt behavioral entrainment to dim light, the latter exacerbated by concomitant loss of melanopsin expression.
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Affiliation(s)
- Olivier Brock
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, United Kingdom
| | - Cigdem Gelegen
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, United Kingdom
| | - Peter Sully
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, United Kingdom
| | - Irene Salgarella
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, United Kingdom
| | - Polona Jager
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, United Kingdom
| | - Lucy Menage
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, United Kingdom
| | - Ishita Mehta
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, United Kingdom
| | - Jagoda Jęczmień-Łazur
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, United Kingdom
| | - Deyl Djama
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, United Kingdom
- Department of Life Sciences and Centre for Neurotechnology, Imperial College London, London SW7 2AZ, United Kingdom
| | - Lauren Strother
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, United Kingdom
| | - Angelica Coculla
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, United Kingdom
| | - Anthony C Vernon
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, United Kingdom
| | - Stephen Brickley
- Department of Life Sciences and Centre for Neurotechnology, Imperial College London, London SW7 2AZ, United Kingdom
| | - Philip Holland
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, United Kingdom
- Wolfson Centre for Age Related Disease, King's College London, London SE1 1UL, United Kingdom
| | - Samuel F Cooke
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, United Kingdom
| | - Alessio Delogu
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, United Kingdom
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Azabou E, Navarro V, Kubis N, Gavaret M, Heming N, Cariou A, Annane D, Lofaso F, Naccache L, Sharshar T. Value and mechanisms of EEG reactivity in the prognosis of patients with impaired consciousness: a systematic review. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2018; 22:184. [PMID: 30071861 PMCID: PMC6091014 DOI: 10.1186/s13054-018-2104-z] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 06/22/2018] [Indexed: 12/21/2022]
Abstract
Background Electroencephalography (EEG) is a well-established tool for assessing brain function that is available at the bedside in the intensive care unit (ICU). This review aims to discuss the relevance of electroencephalographic reactivity (EEG-R) in patients with impaired consciousness and to describe the neurophysiological mechanisms involved. Methods We conducted a systematic search of the term “EEG reactivity and coma” using the PubMed database. The search encompassed articles published from inception to March 2018 and produced 202 articles, of which 42 were deemed relevant, assessing the importance of EEG-R in relationship to outcomes in patients with impaired consciousness, and were therefore included in this review. Results Although definitions, characteristics and methods used to assess EEG-R are heterogeneous, several studies underline that a lack of EEG-R is associated with mortality and unfavorable outcome in patients with impaired consciousness. However, preserved EEG-R is linked to better odds of survival. Exploring EEG-R to nociceptive, auditory, and visual stimuli enables a noninvasive trimodal functional assessment of peripheral and central sensory ascending pathways that project to the brainstem, the thalamus and the cerebral cortex. A lack of EEG-R in patients with impaired consciousness may result from altered modulation of thalamocortical loop activity by afferent sensory input due to neural impairment. Assessing EEG-R is a valuable tool for the diagnosis and outcome prediction of severe brain dysfunction in critically ill patients. Conclusions This review emphasizes that whatever the etiology, patients with impaired consciousness featuring a reactive electroencephalogram are more likely to have a favorable outcome, whereas those with a nonreactive electroencephalogram are prone to having an unfavorable outcome. EEG-R is therefore a valuable prognostic parameter and warrants a rigorous assessment. However, current assessment methods are heterogeneous, and no consensus exists. Standardization of stimulation and interpretation methods is needed.
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Affiliation(s)
- Eric Azabou
- Department of Physiology and Department of Critical Care Medicine, Raymond Poincaré Hospital, Assistance Publique - Hôpitaux de Paris (AP-HP), Inserm UMR 1173 Infection and Inflammation, University of Versailles Saint Quentin (UVSQ), University Paris-Saclay, Garches, Paris, France. .,Clinical Neurophysiology Unit, Raymond Poincaré Hospital - Assistance - Publique Hôpitaux de Paris, INSERM U1173, University of Versailles-Saint Quentin (UVSQ), 104 Boulevard Raymond Poincaré, Garches, 92380, Paris, France.
| | - Vincent Navarro
- Department of Clinical Neurophysiology, Pitié-Salpêtrière Hospital, AP-HP, Inserm UMRS 1127, CNRS UMR 7225, Sorbonne Universities, Université Pierre et Marie Curie - UPMC Université Paris 06, Paris, France
| | - Nathalie Kubis
- Department of Clinical Physiology, Lariboisière Hospital, AP-HP, Inserm U965, University of Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Martine Gavaret
- Department of Clinical Neurophysiology, Sainte-Anne Hospital, Inserm U894, University Paris-Descartes, Paris, France
| | - Nicholas Heming
- Department of Physiology and Department of Critical Care Medicine, Raymond Poincaré Hospital, Assistance Publique - Hôpitaux de Paris (AP-HP), Inserm UMR 1173 Infection and Inflammation, University of Versailles Saint Quentin (UVSQ), University Paris-Saclay, Garches, Paris, France
| | - Alain Cariou
- Medical ICU, Cochin Hospital, AP-HP, Paris Cardiovascular Research Center, INSERM U970, Université Paris Descartes Sorbonne Paris Cité, Paris, France
| | - Djillali Annane
- Department of Physiology and Department of Critical Care Medicine, Raymond Poincaré Hospital, Assistance Publique - Hôpitaux de Paris (AP-HP), Inserm UMR 1173 Infection and Inflammation, University of Versailles Saint Quentin (UVSQ), University Paris-Saclay, Garches, Paris, France
| | - Fréderic Lofaso
- Department of Physiology and Department of Critical Care Medicine, Raymond Poincaré Hospital, Assistance Publique - Hôpitaux de Paris (AP-HP), Inserm UMR 1173 Infection and Inflammation, University of Versailles Saint Quentin (UVSQ), University Paris-Saclay, Garches, Paris, France
| | - Lionel Naccache
- Department of Clinical Neurophysiology, Pitié-Salpêtrière Hospital, AP-HP, Inserm UMRS 1127, CNRS UMR 7225, Sorbonne Universities, Université Pierre et Marie Curie - UPMC Université Paris 06, Paris, France
| | - Tarek Sharshar
- Department of Neuro-Intensive Care Medicine, Sainte-Anne Hospital, Paris-Descartes University, Paris, France
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Brown TM. Using light to tell the time of day: sensory coding in the mammalian circadian visual network. ACTA ACUST UNITED AC 2017; 219:1779-92. [PMID: 27307539 PMCID: PMC4920240 DOI: 10.1242/jeb.132167] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 05/09/2016] [Indexed: 12/31/2022]
Abstract
Circadian clocks are a near-ubiquitous feature of biology, allowing organisms to optimise their physiology to make the most efficient use of resources and adjust behaviour to maximise survival over the solar day. To fulfil this role, circadian clocks require information about time in the external world. This is most reliably obtained by measuring the pronounced changes in illumination associated with the earth's rotation. In mammals, these changes are exclusively detected in the retina and are relayed by direct and indirect neural pathways to the master circadian clock in the hypothalamic suprachiasmatic nuclei. Recent work reveals a surprising level of complexity in this sensory control of the circadian system, including the participation of multiple photoreceptive pathways conveying distinct aspects of visual and/or time-of-day information. In this Review, I summarise these important recent advances, present hypotheses as to the functions and neural origins of these sensory signals, highlight key challenges for future research and discuss the implications of our current knowledge for animals and humans in the modern world.
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Affiliation(s)
- Timothy M Brown
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
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Hanna L, Walmsley L, Pienaar A, Howarth M, Brown TM. Geniculohypothalamic GABAergic projections gate suprachiasmatic nucleus responses to retinal input. J Physiol 2017; 595:3621-3649. [PMID: 28217893 DOI: 10.1113/jp273850] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 02/13/2017] [Indexed: 01/28/2023] Open
Abstract
KEY POINTS Visual input to the suprachiasmatic nucleus circadian clock is critical for animals to adapt their physiology and behaviour in line with the solar day. In addition to direct retinal projections, the clock receives input from the visual thalamus, although the role of this geniculohypothalamic pathway in circadian photoreception is poorly understood. In the present study, we develop a novel brain slice preparation that preserves the geniculohypothalamic pathway to show that GABAergic thalamic neurons inhibit retinally-driven activity in the central clock in a circadian time-dependent manner. We also show that in vivo manipulation of thalamic signalling adjusts specific features of the hypothalamic light response, indicating that the geniculohypothalamic pathway is primarily activated by crossed retinal inputs. Our data provide a mechanism by which geniculohypothalamic signals can adjust the magnitude of circadian and more acute hypothalamic light responses according to time-of-day and establish an important new model for future investigations of the circadian visual system. ABSTRACT Sensory input to the master mammalian circadian clock, the suprachiasmatic nucleus (SCN), is vital in allowing animals to optimize physiology and behaviour alongside daily changes in the environment. Retinal inputs encoding changes in external illumination provide the principle source of such information. The SCN also receives input from other retinorecipient brain regions, primarily via the geniculohypothalamic tract (GHT), although the contribution of these indirect projections to circadian photoreception is currently poorly understood. To address this deficit, in the present study, we established an in vitro mouse brain slice preparation that retains connectivity across the extended circadian system. Using multi-electrode recordings, we first confirm that this preparation retains intact optic projections to the SCN, thalamus and pretectum and a functional GHT. We next show that optogenetic activation of GHT neurons selectively suppresses SCN responses to retinal input, and also that this effect exhibits a pronounced day/night variation and involves a GABAergic mechanism. This inhibitory action was not associated with overt circadian rhythmicity in GHT output, indicating modulation at the SCN level. Finally, we use in vivo electrophysiological recordings alongside pharmacological inactivation or optogenetic excitation to show that GHT signalling actively modulates specific features of the SCN light response, indicating that GHT cells are primarily activated by crossed retinal projections. Taken together, our data establish a new model for studying network communication in the extended circadian system and provide novel insight into the roles of GHT-signalling, revealing a mechanism by which thalamic activity can help gate retinal input to the SCN according to time of day.
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Affiliation(s)
- Lydia Hanna
- Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
| | - Lauren Walmsley
- Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
| | - Abigail Pienaar
- Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
| | - Michael Howarth
- Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
| | - Timothy M Brown
- Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
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Delogu A, Sellers K, Zagoraiou L, Bocianowska-Zbrog A, Mandal S, Guimera J, Rubenstein JLR, Sugden D, Jessell T, Lumsden A. Subcortical visual shell nuclei targeted by ipRGCs develop from a Sox14+-GABAergic progenitor and require Sox14 to regulate daily activity rhythms. Neuron 2012; 75:648-62. [PMID: 22920256 DOI: 10.1016/j.neuron.2012.06.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2012] [Indexed: 11/29/2022]
Abstract
Intrinsically photosensitive retinal ganglion cells (ipRGCs) and their nuclear targets in the subcortical visual shell (SVS) are components of the non-image-forming visual system, which regulates important physiological processes, including photoentrainment of the circadian rhythm. While ipRGCs have been the subject of much recent research, less is known about their central targets and how they develop to support specific behavioral functions. We describe Sox14 as a marker to follow the ontogeny of the SVS and find that the complex forms from two narrow stripes of Dlx2-negative GABAergic progenitors in the early diencephalon through sequential waves of tangential migration. We characterize the requirement for Sox14 to orchestrate the correct distribution of neurons among the different nuclei of the network and describe how Sox14 expression is required both to ensure robustness in circadian entrainment and for masking of motor activity.
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Affiliation(s)
- Alessio Delogu
- MRC Centre for Developmental Neurobiology, School of Medicine, King's College London, London SE1 1UL, UK
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Koletar MM, Cheng HYM, Penninger JM, Ralph MR. Loss ofdexras1Alters Nonphotic Circadian Phase Shifts and Reveals a Role for the Intergeniculate Leaflet (IGL) in Gene-Targeted Mice. Chronobiol Int 2011; 28:553-62. [DOI: 10.3109/07420528.2011.592235] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Abstract
Circadian rhythms in mammals are regulated by a system of endogenous circadian oscillators (clock cells) in the brain and in most peripheral organs and tissues. One group of clock cells in the hypothalamic SCN (suprachiasmatic nuclei) functions as a pacemaker for co-ordinating the timing of oscillators elsewhere in the brain and body. This master clock can be reset and entrained by daily LD (light–dark) cycles and thereby also serves to interface internal with external time, ensuring an appropriate alignment of behavioural and physiological rhythms with the solar day. Two features of the mammalian circadian system provide flexibility in circadian programming to exploit temporal regularities of social stimuli or food availability. One feature is the sensitivity of the SCN pacemaker to behavioural arousal stimulated during the usual sleep period, which can reset its phase and modulate its response to LD stimuli. Neural pathways from the brainstem and thalamus mediate these effects by releasing neurochemicals that inhibit retinal inputs to the SCN clock or that alter clock-gene expression in SCN clock cells. A second feature is the sensitivity of circadian oscillators outside of the SCN to stimuli associated with food intake, which enables animals to uncouple rhythms of behaviour and physiology from LD cycles and align these with predictable daily mealtimes. The location of oscillators necessary for food-entrained behavioural rhythms is not yet certain. Persistence of these rhythms in mice with clock-gene mutations that disable the SCN pacemaker suggests diversity in the molecular basis of light- and food-entrainable clocks.
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Webb IC, Patton DF, Landry GJ, Mistlberger RE. Circadian clock resetting by behavioral arousal: neural correlates in the midbrain raphe nuclei and locus coeruleus. Neuroscience 2010; 166:739-51. [PMID: 20079808 DOI: 10.1016/j.neuroscience.2010.01.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Revised: 01/07/2010] [Accepted: 01/08/2010] [Indexed: 10/19/2022]
Abstract
Some procedures for stimulating arousal in the usual daily rest period (e.g., gentle handling, novel wheel-induced running) can phase shift circadian rhythms in Syrian hamsters, while other arousal procedures are ineffective (inescapable stress, caffeine, modafinil). The dorsal and median raphe nuclei (DRN, MnR) have been implicated in clock resetting by arousal and, in rats and mice, exhibit strong regionally specific responses to inescapable stress and anxiogenic drugs. To examine a possible role for the midbrain raphe nuclei in the differential effects of arousal procedures on circadian rhythms, hamsters were aroused for 3 h in the mid-rest period by confinement to a novel running wheel, gentle handling (with minimal activity) or physical restraint (with intermittent, loud compressed air stimulation) and sacrificed immediately thereafter. Regional expression of c-fos and tryptophan hydroxylase (TrpOH) were quantified immunocytochemically in the DRN, MnR and locus coeruleus (LC). Neither gentle handling nor wheel running had a large impact on c-fos expression in these areas, although the manipulations were associated with a small increase in c-Fos in TrpOH-like and TrpOH-negative cells, respectively, in the caudal interfascicular DRN region. By contrast, restraint stress significantly increased c-Fos in both TrpOH-like and TrpOH-negative cells in the rostral DRN and LC. c-Fos-positive cells in the DRN did not express tyrosine hydroxylase. These results reveal regionally specific monoaminergic correlates of arousal-induced circadian clock resetting, and suggest a hypothesis that strong activation of some DRN and LC neurons by inescapable stress may oppose clock resetting in response to arousal during the daily sleep period. More generally, these results complement evidence from other rodent species for functional topographic organization of the DRN.
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Affiliation(s)
- I C Webb
- Department of Psychology, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
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Abstract
The circadian timing system (CTS) coordinated by the suprachiasmatic nuclei (SCN) of the hypothalamus regulates daily rhythms of behavior, physiology, as well as cellular metabolism and proliferation. Altered circadian rhythms predict for poor survival in cancer patients. An increased incidence of several cancers has been reported in flight attendants and in shift workers. To explore the contribution of the CTS to tumor growth, we developed experimental models of disrupted or enhanced circadian coordination through stereotaxic destruction of the SCN, modifications of photoperiodic or feeding synchronizers and/or the administration of pharmacologic agents. SCN ablation or exposure to experimental chronic jetlag (CJL, consisting of an 8-hour advance of the light-dark cycle every 2 days) caused alterations in circadian physiology and significantly accelerated tumor growth. CJL suppressed or altered the rhythms of clock gene and cell cycle gene expression in mouse liver. It increased p53 and decreased c-Myc expression, a result in line with the promotion of diethylnitrosamine -initiated hepatocarcinogenesis in jet-lagged mice. The accelerating effect of CJL on tumor growth was counterbalanced by the regular timing of food access over the 24-h. Meal timing prevented the circadian disruption produced by CJL and slowed down tumor growth. In synchronized mice, meal timing reinforced host circadian coordination, phase-shifted the transcriptional rhythms of clock genes in the liver of tumor-bearing mice and slowed down cancer progression. These results support the role of the CTS in cancer progression and call for the development of therapeutic strategies aimed at preventing or treating circadian clock dysfunctions.
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Affiliation(s)
- Elisabeth Filipski
- Hôpital Paul Brousse, Villejuif, France, , Université Paris-Sud, Orsay, France
| | - Francis Lévi
- Hôpital Paul Brousse, Villejuif, France, Université Paris-Sud, Orsay, France
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13
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Filipski E, Subramanian P, Carrière J, Guettier C, Barbason H, Lévi F. Circadian disruption accelerates liver carcinogenesis in mice. Mutat Res 2009; 680:95-105. [PMID: 19833225 DOI: 10.1016/j.mrgentox.2009.10.002] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Accepted: 10/02/2009] [Indexed: 11/19/2022]
Abstract
BACKGROUND The circadian timing system rhythmically controls behavior, physiology, cellular proliferation and xenobiotic metabolism over the 24-h period. The suprachiasmatic nuclei in the hypothalamus coordinate the molecular clocks in most mammalian cells through an array of circadian physiological rhythms including rest-activity, body temperature, feeding patterns and hormonal secretions. As a result, shift work that involves circadian disruption is probably carcinogenic in humans. In experimental models, chronic jet-lag (CJL) suppresses rest-activity and body temperature rhythms and accelerates growth of two transplantable tumors in mice. CJL also suppresses or significantly alters the expression rhythms of clock genes in liver and tumors. Circadian clock disruption from CJL downregulates p53 and upregulates c-Myc, thus favoring cellular proliferation. Here, we investigate the role of CJL as a tumor promoter in mice exposed to the hepatic carcinogen, diethylnitrosamine (DEN). METHODS In experiment 1 (Exp 1), the dose-dependent carcinogenicity of chronic intraperitoneal (i.p.) administration of DEN was explored in mice. In Exp 2, mice received DEN at 10 mg/kg/day (cumulative dose: 243 mg/kg), then were randomized to remain in a photoperiodic regimen where 12 h of light alternates with 12 h of darkness (LD 12:12) or to be submitted to CJL (8-h advance of light onset every 2 days). Rest-activity and body temperature were monitored. Serum liver enzymes were determined repeatedly. Mice were sacrificed and examined for neoplastic lesions at 10 months. RESULTS In Exp 1, DEN produced liver cancers in all the mice receiving 10 mg/kg/day. In Exp 2, mice on CJL had increased mean plasma levels of aspartate aminotransferase and more liver tumors as compared to LD mice at approximately 10 months (p = 0.005 and 0.028, respectively). The mean diameter of the largest liver tumor was twice as large in CJL vs LD mice (8.5 vs 4.4 mm, p = 0.027). In LD, a single histologic tumor type per liver was observed. In CJL, up to four different types were associated in the same liver (hepatocellular- or cholangio-carcinomas, sarcomas or mixed tumors). DEN itself markedly disrupted the circadian rhythms in rest-activity and body temperature in all the mice. DEN-induced disruption was prolonged for >or= 3 months by CJL exposure. CONCLUSIONS The association of circadian disruption with chronic DEN exposure suggests that circadian clocks actively control the mechanisms of liver carcinogenesis in mice. Persistent circadian coordination may further be critical for slowing down and/or reverting cancer development after carcinogen exposure.
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Affiliation(s)
- Elisabeth Filipski
- INSERM, U776 Rythmes Biologiques et Cancers, Hôpital Paul Brousse, Villejuif F-94807, France
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14
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Functional neuroanatomy of sleep and circadian rhythms. ACTA ACUST UNITED AC 2009; 61:281-306. [PMID: 19695288 DOI: 10.1016/j.brainresrev.2009.08.001] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Revised: 07/02/2009] [Accepted: 08/07/2009] [Indexed: 11/23/2022]
Abstract
The daily sleep-wake cycle is perhaps the most dramatic overt manifestation of the circadian timing system, and this is especially true for the monophasic sleep-wake cycle of humans. Considerable recent progress has been made in elucidating the neurobiological mechanisms underlying sleep and arousal, and more generally, of circadian rhythmicity in behavioral and physiological systems. This paper broadly reviews these mechanisms from a functional neuroanatomical and neurochemical perspective, highlighting both historical and recent advances. In particular, I focus on the neural pathways underlying reciprocal interactions between the sleep-regulatory and circadian timing systems, and the functional implications of these interactions. While these two regulatory systems have often been considered in isolation, sleep-wake and circadian regulation are closely intertwined processes controlled by extensively integrated neurobiological mechanisms.
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15
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Scheibler E, Wollnik F. Interspecific contact affects phase response and activity in Desert hamsters. Physiol Behav 2009; 98:288-95. [PMID: 19524601 DOI: 10.1016/j.physbeh.2009.06.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Revised: 05/29/2009] [Accepted: 06/04/2009] [Indexed: 11/29/2022]
Abstract
Circadian rhythms enhance survival and reproductive fitness of animals by promoting optimal timing of behavior and physiology with reference to geophysical changes in environment. Although light is considered the dominant stimulus for entraining circadian rhythms, social stimuli can also act as zeitgebers. The aim of this study was to analyze how Desert hamsters (Phodopus roborovskii) coordinate their behavior in time with that of animals of another competing species (Mongolian gerbils, Meriones unguiculatus). First, the behavior of hamsters was analyzed during a step-wise avoidance test. Two effects were observed: a) spatial separation if it was possible or b) shortening of the activity period due to contact without chance for avoidance. The latter finding was now further analyzed using a phase response curve (PRC). Here, phase shifts of Desert hamsters caused by single social interactions with Mongolian gerbils were quantified. Phase advances during the rest period were found at CT3 and CT9, a similar tendency was observed at CT6. A second phase advance was determined at CT18, coinciding with the end of the activity period. Then, it was tested whether additional activity during the stimulus was a trigger for the phase response. Although an increase in activity occurred especially when stimuli were applied during the rest period, there was no general relation between additional activity measured and the phase response shown. Overall, relevance of interspecific contact as nonphotic zeitgeber was indicated by phase shifts in a phase response curve. The shape of it can be explained by two behavioral adaptations; stress and contact avoidance.
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Affiliation(s)
- Elke Scheibler
- University Stuttgart, Biological Institute, Dept. of Animal Physiology, Pfaffenwaldring 57, D - 70569 Stuttgart, Germany.
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16
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Innervation of gonadotropin-releasing hormone neurons by peptidergic neurons conveying circadian or energy balance information in the mouse. PLoS One 2009; 4:e5322. [PMID: 19390688 PMCID: PMC2669176 DOI: 10.1371/journal.pone.0005322] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Accepted: 03/26/2009] [Indexed: 11/30/2022] Open
Abstract
Background Secretion of gonadotropin-releasing hormone (GnRH) produced in neurons in the basal forebrain is the primary regulator of reproductive maturation and function in mammals. Peptidergic signals relating to circadian timing and energy balance are an important influence on the reproductive axis. The aim of this study was to investigate the innervation of GnRH neurons by peptidergic neurons. Methodology/Principal Findings Immunohistochemistry and confocal microscopy were used to detect appositions of peptidergic fibers (NPY, β-endorphin, MCH) associated with energy balance and metabolic status in transgenic mice expressing a green fluorescent protein reporter construct in GnRH neurons. The frequency of these appositions was compared to those of vasoactive intestinal peptide (VIP), a hypothalamic neuropeptide likely to convey circadian timing information to the GnRH secretory system. The majority of GnRH neurons (73–87%) were closely apposed by fibers expressing NPY, β-endorphin, or MCH, and a significant proportion of GnRH neurons (28%) also had close contacts with VIP-ir fibers. Conclusions/Significance It is concluded that GnRH neurons in the mouse receive a high frequency of direct modulatory inputs from multiple hypothalamic peptide systems known to be important in conveying circadian information and signalling energy balance.
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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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18
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Webb IC, Patton DF, Hamson DK, Mistlberger RE. Neural correlates of arousal-induced circadian clock resetting: hypocretin/orexin and the intergeniculate leaflet. Eur J Neurosci 2008; 27:828-35. [DOI: 10.1111/j.1460-9568.2008.06074.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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19
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Szkudlarek H, Raastad M. Electrical properties of morphologically characterized neurons in the intergeniculate leaflet of the rat thalamus. Neuroscience 2007; 150:309-18. [DOI: 10.1016/j.neuroscience.2007.09.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 08/21/2007] [Accepted: 09/11/2007] [Indexed: 11/25/2022]
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20
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Carbachol injections into the intergeniculate leaflet induce nonphotic phase shifts. Brain Res 2007; 1177:59-65. [DOI: 10.1016/j.brainres.2007.07.048] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Revised: 07/12/2007] [Accepted: 07/31/2007] [Indexed: 12/29/2022]
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21
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Freeman DA, Teubner BJW, Goldman BD. The thalamic intergeniculate leaflet mediates locomotor activity-induced reversal of phenotype in photoperiod nonresponsive Siberian hamsters. J Biol Rhythms 2006; 21:206-13. [PMID: 16731660 DOI: 10.1177/0748730406287996] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The role of the intergeniculate leaflet of the thalamus (IGL) in photoperiod responsiveness was examined in a laboratory-selected line of photoperiod nonresponsive (NR) Siberian hamsters. NR hamsters fail to exhibit typical winter-type responses (i.e., gonadal regression and development of winter-type pelage) when exposed to short day lengths (e.g., 10 h of light/day). Earlier studies revealed that NR hamsters will exhibit winter-type responses when exposed to short photoperiod if they are given free access to a running wheel. The present study tested the hypothesis that this locomotor activity-induced reversal of phenotype is dependent on the IGL. Male NR hamsters underwent destruction of the IGL prior to being housed in short day lengths in cages equipped with running wheels. Activity rhythms were monitored for 8 weeks, after which time pelage response and paired testes weights were obtained. In contrast to sham-operated NR animals given access to running wheels, IGL-ablated animals showed no increase in the duration of nocturnal running wheel activity and became active later in the night than sham-lesioned animals. Lesioned animals also failed to exhibit the typical short photoperiod-induced gonadal regression and pelage molt. The results implicate the IGL in the mechanism by which running wheel activity can influence photoperiodic responses.
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Affiliation(s)
- David A Freeman
- Department of Biology, University of Memphis, Memphis, TN 38152-3540, USA.
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22
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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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23
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Abstract
UNLABELLED Altered circadian rhythms predicted for poor survival in patients with metastatic colorectal or breast cancer. An increased incidence of cancers has been reported in flying attendants and in women working predominantly at night. To explore the contribution of circadian structure to tumor growth we ablated the 24-h rest-activity cycle and markedly altered the rhythms in body temperature, serum corticosterone and lymphocyte count in mice by complete stereotaxic destruction of the suprachiasmatic nuclei (SCN) or by subjecting the mice to experimental chronic jet-lag. Such disruption of circadian coordination significantly accelerated malignant growth in two transplantable tumor models, Glasgow osteosarcoma and Pancreatic adenocarcinoma. The mRNA expression of clock genes per2 and reverb-alpha in controls displayed significant circadian rhythms in the liver (Cosinor, p=0.006 and p=0.003, respectively) and in the tumor (p=0.04 and p<0.001, respectively). Both rhythms were suppressed in the liver and in the tumor of jet lagged mice. This functional disturbance of molecular clock resulted in down regulation of p53 and overexpression of c-Myc, two effects which may favor cancer growth. CONCLUSIONS These results indicate that circadian system could play an important role in malignant growth control. This should be taken into consideration in cancer prevention and therapy.
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Affiliation(s)
- Elizabeth Filipski
- INSERM E 354 Cancer Chronotherapeutics, Hôpital Paul Brousse, Villejuif, France.
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24
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Thankachan S, Rusak B. Juxtacellular recording/labeling analysis of physiological and anatomical characteristics of rat intergeniculate leaflet neurons. J Neurosci 2005; 25:9195-204. [PMID: 16207879 PMCID: PMC6725760 DOI: 10.1523/jneurosci.2672-05.2005] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The thalamic intergeniculate leaflet (IGL) is involved in mediating effects of both photic and nonphotic stimuli on mammalian circadian rhythms. IGL neurons containing neuropeptide Y (NPY) have been implicated in mediating nonphotic effects, but little is known about those involved in photic entrainment. We used juxtacellular recording/labeling in rats to characterize both photic responses and neurochemical phenotypes of neurons in the lateral geniculate area, focusing on the IGL and ventral lateral geniculate (VLG). Single neurons were recorded to characterize photic responsiveness and were labeled with Neurobiotin (Nb); tissue was stained for Nb, NPY, and in some cases for orexin A. Three classes of neurons were identified in the IGL/VLG. Type I neurons lacked NPY and showed sustained activations during retinal illumination and moderate firing rates in darkness. Type II neurons contained large amounts of NPY throughout the soma and showed varied responses to illumination: suppression, complex responses, or no response. Type III neurons had patches of NPY both on the external soma surface and within the soma, apparently representing internalization of NPY. Type III neurons resembled type I cells in their sustained activation by illumination but were virtually silent during the intervening dark period. These neurons appear to receive NPY input, presumably from other IGL cells, which may suppress their activity during darkness. These results demonstrate the presence of several classes of neurons in the IGL defined by their functional and anatomical features and reinforce the role of the IGL/VLG complex in integrating photic and nonphotic inputs to the circadian system.
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Affiliation(s)
- Stephen Thankachan
- Department of Psychology, Dalhousie University, Halifax, Nova Scotia, B3H 4J1, Canada
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25
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Abstract
In mammals, circadian rhythms are driven by a pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus. We measured the rhythm of arginine vasopressin release in rat organotypic SCN slices following application of tetrodotoxin (TTX) or N-methyl-D-aspartate (NMDA) at various times throughout the circadian cycle. TTX resets the clock in a manner similar to dark pulses. A 4-h application of TTX starting in mid subjective day, at around circadian time (CT) 7.0, induced phase advances, while TTX treatment started in early subjective morning, at about CT 2.0, induced phase delays. On the other hand, NMDA resets the clock in a manner similar to a light pulse; that is, NMDA treatment in the early evening induced phase delays while treatment in the late night induced phase advances. The data indicate that deprivation of neuronal firing changes the circadian rhythm.
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Affiliation(s)
- Takako Noguchi
- Department of Physiology, Dokkyo University School of Medicine, 880 Kitakobayashi, Mibu, Tochigi 321-0293, Japan
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26
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Roenneberg T, Dragovic Z, Merrow M. Demasking biological oscillators: properties and principles of entrainment exemplified by the Neurospora circadian clock. Proc Natl Acad Sci U S A 2005; 102:7742-7. [PMID: 15899977 PMCID: PMC1140435 DOI: 10.1073/pnas.0501884102] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2005] [Indexed: 11/18/2022] Open
Abstract
Oscillations are found throughout the physical and biological worlds. Their interactions can result in a systematic process of synchronization called entrainment, which is distinct from a simple stimulus-response pattern. Oscillators respond to stimuli at some times in their cycle and may not respond at others. Oscillators can also be driven if the stimulus is strong (or if the oscillator is weak); i.e., they restart their cycle every time they receive a stimulus. Stimuli can also directly affect rhythms without entraining the underlying oscillator (masking): Drivenness and masking are often difficult to distinguish. Here we use the circadian biological clock to explore properties of entrainment. We confirm previous results showing that the residual circadian system in Neurospora can be entrained in a mutant of the clock gene frequency (frq(9), a strain deficient in producing a functional FRQ protein). This finding has implications for understanding the evolution of circadian programs. By comparing data sets from independent studies, we develop a template for analyzing, modeling, and dissecting the interactions of entrained and masked components. These insights can be applied to oscillators of all periodicities.
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Affiliation(s)
- Till Roenneberg
- Centre for Chronobiology, Institute of Medical Psychology, Medical Faculty, University of Munich, Goethestrasse 31, D-80336 Munich, Germany.
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27
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Freeman DA, Dhandapani KM, Goldman BD. The thalamic intergeniculate leaflet modulates photoperiod responsiveness in Siberian hamsters. Brain Res 2004; 1028:31-8. [PMID: 15518639 DOI: 10.1016/j.brainres.2004.08.049] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2004] [Indexed: 10/26/2022]
Abstract
Siberian hamsters are seasonal breeders that use changes in day length to synchronize their reproductive effort with those times of the year most favorable for successful reproduction. The ability of Siberian hamsters to measure and respond to changes in day length depends upon accurate photoentrainment of the circadian clock in the suprachiasmatic nucleus (SCN) of the hypothalamus. Two pathways have been characterized through which entraining stimuli reach the SCN: the retinohypothalamic tract (RHT), which transmits light information from the retinae, and the geniculohypothalamic tract (GHT) from the intergeniculate leaflet of the thalamus (IGL), which is involved in transmitting both photic and nonphotic cues. Ablating the IGL/GHT results in only modest alterations in entrainment to static day lengths and fails to interfere with seasonal responses induced by transfer from static long day to static short day lengths. Because several studies suggest that the IGL may be involved in tracking the time of dusk and dawn, we sought to determine whether an intact IGL is necessary for hamsters to respond to a simulated natural photoperiod (SNP) in which the time of dusk and dawn gradually changes in a pattern approximating the rate of change in day length that occurs during autumn at the latitude this species inhabits in nature. The results indicate that neurochemical lesions of the IGL alter both the pattern of circadian entrainment and photoperiodic responsiveness of Siberian hamsters to an SNP. Both intact and IGL-lesioned hamsters exhibited testicular regression in shortening day lengths, but only IGL-intact hamsters exhibited seasonal pelage molt.
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Affiliation(s)
- David A Freeman
- Department of Biology, 103 Ellington Hall, University of Memphis, Memphis, TN 38152, USA.
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28
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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: 74] [Impact Index Per Article: 3.7] [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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29
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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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30
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Cain SW, Verwey M, Hood S, Leknickas P, Karatsoreos I, Yeomans JS, Ralph MR. Reward and Aversive Stimuli Produce Similar Nonphotic Phase Shifts. Behav Neurosci 2004; 118:131-7. [PMID: 14979789 DOI: 10.1037/0735-7044.118.1.131] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Circadian rhythms in rodents respond to arousing, nonphotic stimuli that contribute to daily patterns of entrainment. To examine whether the motivational significance of a stimulus is important for eliciting nonphotic circadian phase shirts in Syrian hamsters (Mesocricetus auratus), the authors compared responses to a highly rewarding stimulus (lateral hypothalamic brain stimulation reward [BSR]) and a highly aversive stimulus (footshock). Animals were housed on a 14:10-hr light-dark cycle until test day, when they were given a 1-hr BSR session (trained animals) or a 1-mA electric footshock at 1 of 8 circadian times, and were maintained in constant dark thereafter. Both BSR pulses and footshock produced nonphotic phase response curves. These results support the hypothesis that arousal resulting from the motivational significance of a stimulus is a major factor in nonphotic phase shifts.
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Affiliation(s)
- Sean W Cain
- Department of Psychology, University of Toronto, Toronto, ON, Canada.
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Mendoza JY, Dardente H, Escobar C, Pevet P, Challet E. Dark pulse resetting of the suprachiasmatic clock in Syrian hamsters: behavioral phase-shifts and clock gene expression. Neuroscience 2004; 127:529-37. [PMID: 15262341 DOI: 10.1016/j.neuroscience.2004.05.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2002] [Revised: 04/27/2002] [Accepted: 05/13/2004] [Indexed: 11/15/2022]
Abstract
In mammals, the circadian clock in the suprachiasmatic nuclei (SCN) is mainly synchronized to photic cues provided by the daily light/dark cycle. Phase-shifts produced by light exposure during the night are correlated with rapid induction of two clock genes, Per1 and Per2, in the SCN. Nonphotic stimuli such as behavioral and pharmacological cues, when presented during the subjective day, induce behavioral phase-advances and a down-regulation of Per1 and Per2 expression in the SCN. When applied during the subjective day, dark pulses in continuous light also produce phase-advances. These phase-shifting effects have been interpreted as reflecting either a photic image mirror, nonphotic cues, or a combination of both. Here we evaluated in Syrian hamsters housed in constant light how dark pulses applied in late subjective day affect levels of Per1, Per2 and Cry1 mRNA. Four-hour dark pulses with no access to a wheel produced 1.2+/-0.4 h phase-advances of locomotor activity rhythm while control manipulation induced non-significant shifts (0.1+/-0.2 h). Dark pulses transiently down-regulated Per1 and Per2 mRNA levels in the SCN by 40 and 20% respectively, while the levels of Cry1 mRNA remained unaffected. In behaviorally split hamsters in which Per oscillations were asymmetric between the left and right sides of the SCN, dark pulses reduced Per expression in the half-SCN with high Per. This study shows that exposure during the late subjective day to dark pulses independent of wheel-running have nonphotic-like effects on the SCN clock at both behavioral and molecular levels.
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Affiliation(s)
- J Y Mendoza
- Laboratory of Neurobiology of Rhythms, University Louis Pasteur, Department of Neuroscience (IFR37), 12 rue de l'Université, 67000 Strasbourg, France
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Evans JA, Elliott JA, Gorman MR. Photoperiod differentially modulates photic and nonphotic phase response curves of hamsters. Am J Physiol Regul Integr Comp Physiol 2003; 286:R539-46. [PMID: 14644756 DOI: 10.1152/ajpregu.00456.2003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Circadian pacemakers respond to light pulses with phase adjustments that allow for daily synchronization to 24-h light-dark cycles. In Syrian hamsters, Mesocricetus auratus, light-induced phase shifts are larger after entrainment to short daylengths (e.g., 10 h light:14 h dark) vs. long daylengths (e.g., 14 h light:10 h dark). The present study assessed whether photoperiodic modulation of phase resetting magnitude extends to nonphotic perturbations of the circadian rhythm and, if so, whether the relationship parallels that of photic responses. Male Syrian hamsters, entrained for 31 days to either short or long daylengths, were transferred to novel wheel running cages for 2 h at times spanning the entire circadian cycle. Phase shifts induced by this stimulus varied with the circadian time of exposure, but the amplitude of the resulting phase response curve was not markedly influenced by photoperiod. Previously reported photoperiodic effects on photic phase resetting were verified under the current paradigm using 15-min light pulses. Photoperiodic modulation of phase resetting magnitude is input specific and may reflect alterations in the transmission of photic stimuli.
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Affiliation(s)
- J A Evans
- Department of Psychology, University of California, San Diego, La Jolla, California 92093, USA.
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33
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Mistlberger RE, Antle MC, Webb IC, Jones M, Weinberg J, Pollock MS. Circadian clock resetting by arousal in Syrian hamsters: the role of stress and activity. Am J Physiol Regul Integr Comp Physiol 2003; 285:R917-25. [PMID: 12842864 DOI: 10.1152/ajpregu.00222.2003] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Circadian rhythms in the Syrian hamster can be markedly phase shifted by 3 h of wheel running or arousal stimulation during their usual daily rest period ("subjective day"). Continuous wheel running is predictive but not necessary for phase shifts of this "nonphotic" type; hamsters aroused by gentle handling without running can also show maximal shifts. By contrast, physical restraint, a standard stress procedure and thus presumably arousing, is ineffective. To resolve this apparent paradox, phase-shifting effects of 3-h sessions of restraint or other stress procedures were assessed. In a preliminary study, phase shifts to arousal by gentle handling were significantly potentiated by the cortisol synthesis inhibitor metyrapone, suggesting that stress-related cortisol release may inhibit phase shifts to arousal. Next, it was confirmed that restraint in the subjective day does not induce phase shifts, but behavioral observations revealed that it also does not sustain arousal. Restraint combined with noxious compressed air blasts did sustain arousal and induced a significant cortisol response compared with arousal by gentle handling but did not induce shifts. Restraint combined with continuous horizontal rotation was also ineffective, as was EEG-validated arousal via confinement to a pedestal over water. However, 3 h of resident-intruder interactions (an intense psychosocial stress) or exposure to an open field (a mild stress) did induce large shifts that were positively correlated with indexes of forward locomotion. The results indicate that large phase shifts associated with arousal in the usual sleep period are neither induced nor prevented by stress per se, but are dependent on the expression of at least low levels of locomotor activity. Sustained arousal alone is not sufficient.
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Affiliation(s)
- R E Mistlberger
- Department of Psychology, Simon Fraser University Burnaby, Canada V5A 1S6.
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34
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Menet JS, Vuillez P, Saboureau M, Pévet P. Inhibition of hibernation by exercise is not affected by intergeniculate leaflets lesion in hamsters. Am J Physiol Regul Integr Comp Physiol 2003; 285:R690-700. [PMID: 12714353 DOI: 10.1152/ajpregu.00068.2003] [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] [Indexed: 11/22/2022]
Abstract
The circadian clock of mammals, located in the suprachiasmatic nuclei (SCN) of the hypothalamus, has been demonstrated to integrate day length change from long (LP) to short photoperiod (SP). This photoperiodic change induces in Syrian hamsters a testicular regression through melatonin action, a phenomenon that is inhibited when hamsters have free access to a wheel. The intergeniculate leaflets (IGL), which modulate the integration of photoperiod by the SCN, are a key structure in the circadian system, conveying nonphotic information such as those induced by novelty-induced wheel running activity. We tested in hamsters transferred from LP to a cold SP the effects of wheel running activity on a photoperiod-dependent behavior, hibernation. Lesions of the IGL were done to test the role of this structure in the inhibition induced by exercise of photoperiod integration by the clock. We show that wheel running activity actually inhibits hibernation not only in sham-operated animals, but also in hamsters with a bilateral IGL lesion (IGLX). In contrast, IGL-X hamsters without a wheel integrate slower to the SP but hibernate earlier compared with sham-operated animals. Moreover, some hibernation characteristics are affected by IGL lesion. Throughout the experiment at 7 degrees C, IGL-X hamsters were in hypothermia during 18% of the experiment vs. 32% for sham-operated hamsters. Taken together, these data show that the IGL play a modulatory role in the integration of photoperiodic cues and modulate hibernation, but they are not implicated in the inhibition of hibernation induced by wheel running activity.
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Affiliation(s)
- Jérôme S Menet
- CNRS-UMR 7518, Neurobiologie des Rythmes, Université Louis Pasteur, IFR37 Neurosciences, 12 rue de l'Université, 67000 Strasbourg, France
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35
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Vrang N, Mrosovsky N, Mikkelsen JD. Afferent projections to the hamster intergeniculate leaflet demonstrated by retrograde and anterograde tracing. Brain Res Bull 2003; 59:267-88. [PMID: 12464399 DOI: 10.1016/s0361-9230(02)00875-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The intergeniculate leaflet (IGL) is considered involved in nonphotic shifting of the circadian clock through a direct connection, the geniculo-hypothalamic tract. The brain areas mediating nonphotic arousal to the hamster IGL have not been thoroughly investigated by both retrograde and anterograde tracing. We, therefore, reinvestigated the IGL afferent connections with the retrograde tracer Cholera toxin B and subsequently verified the results with the anterograde tracer Phaseolus vulgaris-leucoagglutinin. We also defined a subset of neurons projecting to the IGL that were activated by arousal using c-Fos immunocytochemistry. Apart from a dense afferent projection from the retina- and the contralateral leaflet, there were ipsilateral projections from other structures: layer V and VI of the prefrontal cortex, the zona incerta, the magnocellular part of the subparafascicular nucleus, the dorsal raphe nucleus, the locus coeruleus, and the cuneiform nucleus. Dense bilateral projections to the leaflet from the pretectal nuclei were found. Hypothalamic afferents were observed dorsal to the suprachiasmatic nuclei, in the retrochiasmatic area (RCh) and in the ventromedial hypothalamic nuclei. All of these projections were confirmed by anterograde tracing. Furthermore, arousal (wheel-running) induced c-Fos in neurons projecting to the IGL (prefrontal cortex, RCh, pretectum). Taken together, the data strengthen the view that the IGL integrates photic and nonphotic information.
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Affiliation(s)
- Niels Vrang
- Rheoscience A/S, Glerupvej 2, Rødovre, Denmark.
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36
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Amir S, Beaulé C, Arvanitogiannis A, Stewart J. Modes of plasticity within the mammalian circadian system. PROGRESS IN BRAIN RESEARCH 2002; 138:191-203. [PMID: 12432771 DOI: 10.1016/s0079-6123(02)38079-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Affiliation(s)
- Shimon Amir
- Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, 1455 de Maisonneuve Boulevard, West, Montreal, QC, H3G 1M8, Canada.
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37
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Lall GS, Biello SM. Attenuation of phase shifts to light by activity or neuropeptide Y: a time course study. Brain Res 2002; 957:109-16. [PMID: 12443986 DOI: 10.1016/s0006-8993(02)03610-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Circadian rhythms in mammals can be synchronised to photic and non-photic stimuli. Interactions between photic and behavioural stimuli were investigated during the late subjective night, 6 h after activity onset in Syrian hamsters (CT18). Light pulses of 130 lx for 15 min at this time resulted in phase advance shifts. Novel wheel exposure, for a period of 3 h, following photic stimulation was able to attenuate the phase advancing effects of light. A time delay of up to 60 min between photic and behavioural stimuli also resulted in significant attenuation of light-induced phase shifts (P<0.05). A 90-min interval between stimuli resulted in no significant attenuation. Novel wheel exposure mediates its effects via the intergeniculate leaflet, which conveys information to the SCN and utilises neuropeptide Y (NPY) as its primary neurotransmitter. Phase shifts to light pulses given at CT18 were attenuated by NPY administration. Neuropeptide Y injections up to 60 min post-light exposure significantly attenuated phase shifts by 50% on average. However a 90-min interval between light and NPY microinjection did not significantly affect light-induced phase shifts. These results confirm previous work indicating that novel wheel exposure and NPY administration can modulate light-induced phase shifts during the late night. Further, they show for the first time that the time course for this interaction is similar between wheel running and NPY. Most significantly, our work indicates that the time course in vivo in the late night is similar to that shown previously in vitro during the early night.
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Affiliation(s)
- Gurprit S Lall
- Department of Psychology, University of Glasgow, 58 Hillhead Street, G12 8QB, Glasgow, UK
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38
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Thomas L, Purvis CC, Drew JE, Abramovich DR, Williams LM. Melatonin receptors in human fetal brain: 2-[(125)I]iodomelatonin binding and MT1 gene expression. J Pineal Res 2002; 33:218-24. [PMID: 12390504 DOI: 10.1034/j.1600-079x.2002.02921.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The purpose of this study was to identify sites of action of melatonin in the human fetal brain by in vitro autoradiography and in situ hybridization. Specific, guanosine triphosphate (GTP) sensitive, binding of 2-[(125)I]iodomelatonin was localized to the leptomeninges, cerebellum, thalamus, hypothalamus, and brainstem. In the hypothalalmus, specific binding was present in the suprachiasmatic nuclei (SCN) as well as the arcuate, ventromedial and mammillary nuclei. In the brainstem specific binding was present in the cranial nerve nuclei including the oculomotor nuclei, the trochlear nuclei, the motor and sensory trigeminal nuclei, the facial nuclei, and the cochlear nuclei. The localization of MT1 receptor subtype gene expression as determined by in situ hybridization matched the localization of 2-[(125)I]iodomelatonin binding. No MT2 receptor subtype gene expression was detected using this technique. Thus, melatonin may act on the human fetus via the MT1 receptor subtype at a number of discrete brain sites. A major site of action of melatonin in both fetal and adult mammals is the pars tuberalis of the pituitary gland. However, no 2-[(125)I]iodomelatonin binding or melatonin receptor gene expression was detected in the pituitary gland in the present study, indicating that the pituitary, particularly the pars tuberalis, is not a site of action of melatonin in the human fetus.
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Affiliation(s)
- Louise Thomas
- Molecular Neuroendocrinology and Phytochemical and Genome Stability Groups, Rowett Research Institute, Bucksburn, Aberdeen, Scotland, UK
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39
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Mistlberger RE, Belcourt J, Antle MC. Circadian clock resetting by sleep deprivation without exercise in Syrian hamsters: dark pulses revisited. J Biol Rhythms 2002; 17:227-37. [PMID: 12054194 DOI: 10.1177/07430402017003006] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Circadian rhythms in Syrian hamsters can be phase shifted by procedures that stimulate wheel running ("exercise") in the mid-subjective day (the hamster's usual sleep period). The authors recently demonstrated that keeping hamsters awake by gentle handling, without continuous running, is sufficient to mimic this effect. Here, the authors assessed whether wakefulness, independent of wheel running, also mediates phase shifts to dark pulses during the midsubjective day in hamsters free-running in constant light (LL). With running wheels locked during a 3 h dark pulse on day 3 of LL, hamsters (N = 16) averaged only 43+/-15 min of spontaneous wake time and phase shifted only 24+/-43 min. When wheels were open during a dark pulse, two hamsters remained awake, ran continuously, and showed phase advance shifts of 7.3 h and 8.7 h, respectively, whereas the other hamsters were awake <60 min and shifted only 45+/-38 min. No animals stayed awake for 3 h without running. Additional time in LL (10 and 20 days) did not potentiate the waking or phase shift response to dark pulses. When all hamsters were sleep deprived with wheels locked during a dark pulse, phase advance shifts averaged 261+/-110 min and ranged up to 7.3 h. These shifts are large compared to those previously observed in response to the 3 h sleep deprivation procedure. Additional tests revealed that this potentiated shift response is dependent on LL prior to sleep deprivation but not LL after sleep deprivation. A final sleep deprivation test showed that a small part of the potentiation may be due to suppression of spontaneous wheel running by LL. These results indicate that some correlate of waking, other than continuous running, mediates the phase-shifting effect of dark pulses in the mid-subjective day. The mechanism by which LL potentiates shifting remains to be determined. The lack of effect of subsequent LL on the magnitude of shifts to sleep deprivation in the dark suggests that LL reduces responsivity to light by processes that take >3 h of dark to reverse.
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Affiliation(s)
- Ralph E Mistlberger
- Department of Psychology, Simon Fraser University, Burnaby, British Columbia, Canada.
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40
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Maywood ES, Okamura H, Hastings MH. Opposing actions of neuropeptide Y and light on the expression of circadian clock genes in the mouse suprachiasmatic nuclei. Eur J Neurosci 2002; 15:216-20. [PMID: 11860521 DOI: 10.1046/j.0953-816x.2001.01852.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The circadian clockwork of the hypothalamic suprachiasmatic nuclei (SCN) is synchronized by light and by nonphotic cues. The core timing mechanism is cell-autonomous, based on an autoregulatory transcriptional/translational feedback loop of circadian genes and their products. This study investigated the effects of neuropeptide Y (NPY), a potent nonphotic resetting cue, and its interaction with light in regulating clock gene expression in the SCN in vivo. Injection of NPY adjacent to the SCN and transfer to darkness 7 h before scheduled lights out, shifted the circadian activity-rest cycle. Exposure to light for 1 h immediately after NPY infusion blocked this behavioural response. NPY-induced shifts were accompanied by suppression of both mPer1 and mPer2 mRNA in the SCN, assessed 3 h after infusion. mPer mRNAs were not altered 1 h after infusion. Levels of mClock mRNA or mCLOCK immunoreactivity in the SCN were not affected by NPY at either time point. In parallel to the behavioural response, the NPY-induced suppression of mPer genes in the SCN was attenuated when a light pulse was delivered immediately after the infusion. These results identify mPer1 and mPer2 as molecular targets for both photic and nonphotic (NPY-induced) resetting of the clockwork, and support a synthetic model of circadian entrainment based upon convergent up- and downregulation of mPer expression.
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41
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Menet J, Vuillez P, Jacob N, Pévet P. Intergeniculate leaflets lesion delays but does not prevent the integration of photoperiodic change by the suprachiasmatic nuclei. Brain Res 2001; 906:176-9. [PMID: 11430876 DOI: 10.1016/s0006-8993(01)02518-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The duration of the photosensitive phase of the suprachiasmatic nuclei (SCN), as revealed by light-induced Fos protein expression, depends on the photoperiod and is tied to the length of the night. We show here in Syrian hamsters that after a transfer from long to short photoperiod, lengthening of the photosensitive phase of the SCN is significantly delayed but not abolished when the intergeniculate leaflets (IGL) are lesioned. Thus IGL modulate the integration by the SCN of a photoperiodic change.
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Affiliation(s)
- J Menet
- CNRS-UMR 7518, Neurobiologie des Fonctions Rythmiques et Saisonnières, Université Louis Pasteur, 12 rue de l'Université, 67000 Strasbourg, France
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42
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Schaap J, Meijer JH. Opposing effects of behavioural activity and light on neurons of the suprachiasmatic nucleus. Eur J Neurosci 2001; 13:1955-62. [PMID: 11403689 DOI: 10.1046/j.0953-816x.2001.01561.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mammalian circadian pacemaker is located in the suprachiasmatic nuclei. It can be shifted in phase by photic cues and by the behavioural activity of the animal. When presented together, light and behavioural activity attenuate each others' phase-shifting effect. Still unclear is how behavioural activity affects the suprachiasmatic nuclei and how it interacts with photic information. Previously, we reported the occurrence of behaviourally induced suppressions of neuronal activity. The present study investigates the characteristics of these suppressions as a function of circadian time and, additionally, in the presence of photic cues. We performed long-term multiunit activity recordings of neurons in freely moving rats and found that these suppressions of neuronal firing in the suprachiasmatic nucleus occurred at every phase of the circadian cycle. The magnitude of the suppressions showed a circadian variation, with larger suppressions during subjective day. When a light pulse was applied during a suppression, light and activity appeared to oppose each others' effects within the recorded population of neurons. The resulting discharge level appeared to be the sum of both responses. The opposing effects of light and activity were also found in single unit recordings, indicating that photic and behavioural stimuli interact at the level of a single neuron.
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Affiliation(s)
- J Schaap
- Department of Physiology, Leiden University Medical Center, Wassenaarseweg 62, PO Box 9604, 2300 RC Leiden, The Netherlands.
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43
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Smale L, Mcelhinny T, Nixon J, Gubik B, Rose S. Patterns of wheel running are related to Fos expression in neuropeptide-Y-containing neurons in the intergeniculate leaflet of Arvicanthis niloticus. J Biol Rhythms 2001; 16:163-72. [PMID: 11302558 DOI: 10.1177/074873001129001863] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A variety of nonphotic influences on circadian rhythms have been documented in mammals. In hamsters, one such influence, running in a novel wheel, is mediated in part by the pathway extending from neuropeptide-Y (NPY)-containing cells within the intergeniculate leaflet (IGL) of the thalamus to the hypothalamic suprachiasmatic nucleus (SCN). Arvicanthis niloticus is a species in which all individuals are diurnal with respect to general activity and body temperature when they are housed without a running wheel, but access to a running wheel induces a subset of individuals to become nocturnal. In the first study, the authors evaluated the possibility that nocturnal and diurnal patterns of wheel running in Arvicanthis are correlated with differences in IGL function. Adult male Arvicanthis housed in a 12:12 light-dark (LD) cycle were monitored in wheels, classified as nocturnal or diurnal, and then perfused either 4 h after lights-on or 4 h after lights-off. Sections through the intergeniculate leaflet were processed for immunohistochemical labeling of Fos and NPY. The percentage of NPY cells that expressed Fos was significantly influenced by an interaction between time of day and phenotype such that it rose from night to day in diurnal animals, and from day to night in nocturnal animals. In the second experiment, the authors established that running in a wheel actually induces Fos in the IGL of Arvicanthis. Specifically, the proportion of NPY cells expressing Fos was increased by access to wheels in nocturnal animals at night and in diurnal animals during the day. In the third experiment, the authors established that lesions of the IGL eliminate NPY fibers within the SCN, suggesting that these IGL cells project to the SCN in this species as has been established in other rodents. Together, these data demonstrate a clear difference in NPY cell function in nocturnal and diurnal Arvicanthis that appears to be caused, at least in part, by the differences in their wheel-running patterns, and that NPY cells within the IGL project to the SCN in Arvicanthis.
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Affiliation(s)
- L Smale
- Department of Psychology, Michigan State University, East Lansing 48824, USA
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44
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Arvanitogiannis A, Robinson B, Beaulé C, Amir S. Calbindin-D28k immunoreactivity in the suprachiasmatic nucleus and the circadian response to constant light in the rat. Neuroscience 2001; 99:397-401. [PMID: 11029532 DOI: 10.1016/s0306-4522(00)00327-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Recent studies in the hamster have led to the discovery that the expression of the calcium binding protein, calbindin-D28k, is a defining feature of neurons in the suprachiasmatic nucleus involved in the regulation of circadian rhythms by environmental light.(2,18, 19,32) To study further the involvement of calbindin-D28k, we examined the effect of exposure to constant light on calbindin-D28k immunoreactivity in the suprachiasmatic nucleus of intact rats and of rats treated neonatally with the retinal neurotoxin, monosodium glutamate. Exposure to constant light is known to disrupt circadian rhythms in rodents and we found previously that treatment with monosodium glutamate selectively prevents the disruptive effect of constant light on circadian rhythms in rats.(7,9) In the present study we found that exposure to light suppresses calbindin-D28k expression in the ventrolateral retinorecipient region of the suprachiasmatic nucleus of rats and that neonatal treatment with monosodium glutamate blocks the suppressive effect of constant light on calbindin-D28k expression. These findings are consistent with the proposed role of calbindin-D28k in photic signaling in the suprachiasmatic nucleus,(32) and point to the possibility that suppression of calbindin-D28k expression is linked to the mechanism by which constant light disrupts circadian rhythms.
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Affiliation(s)
- A Arvanitogiannis
- Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montreal, Quebec, Canada
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45
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Abstract
Circadian rhythms in several species can be phase-shifted by procedures that stimulate locomotor activity ("exercise") during the usual sleep period. The role of arousal or sleep loss, independent of activity, in this effect has not been adequately resolved. We show here, using the sleep deprivation procedure of gentle handling, that comparably large phase shifts (up to 240 min advances) of the rest-activity cycle can be induced in Syrian hamsters by 3 hr of behavioral arousal, with minimal locomotion, beginning 6 hr before the usual active period. Horizontal distance traveled during the deprivation procedure averaged approximately 0.08 km, compared to 2. 5 km typical in exercise studies. Hamsters requiring fewer interventions exhibited larger shifts, suggesting that the level or continuity of spontaneous arousal determines shift size. The circadian rhythm of light-induced c-fos expression in the suprachiasmatic nucleus (SCN) was used as a phase marker to further demonstrate that the clock is reset within 1 hr after a 3 hr deprivation. Sleep deprivation mimicked the effects of exercise on basal c-fos expression in two components of the circadian system, suppressing basal Fos immunoreactivity in the SCN, and increasing Fos in the intergeniculate leaflet. Sleep deprivation without exercise in hamsters can rapidly reset the circadian clock and alter gene expression within the circadian system.
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Goel N, Governale MM, Jechura TJ, Lee TM. Effects of intergeniculate leaflet lesions on circadian rhythms in Octodon degus. Brain Res 2000; 877:306-13. [PMID: 10986345 DOI: 10.1016/s0006-8993(00)02696-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The intergeniculate leaflet (IGL) modulates photic and nonphotic entrainment of circadian rhythms in nocturnal species, but nothing is known about its role in diurnal species. We investigated the significance of the IGL for circadian rhythm function in the diurnal rodent, Octodon degus, by determining the effects of bilateral electrolytic IGL lesions (IGL(X)) on: (i) photic entrainment; (ii) reentrainment rates to photic cues following a 6-h phase advance of the light-dark (LD) cycle; (iii) reentrainment rates to nonphotic social and photic cues following a 6-h phase advance of the LD cycle; and (iv) the circadian period (tau) of the activity rhythm in constant darkness (DD). IGL(X) significantly lengthened the duration (alpha) of the entrained activity rhythm and produced a significantly earlier phase of activity onset under entrained (LD 12:12) conditions, but did not change phase of activity offset, rhythm amplitude or mean daily activity levels. IGL(X) failed to modify tau of free-running activity rhythms in DD or alter reentrainment rates of circadian rhythms to nonphotic social and photic cues or photic cues alone. Thus, the IGL modulates two parameters of photic entrainment, but is not necessary for reentrainment to either nonphotic social or photic cues. Our results contribute to the growing comparative database on the neural mechanisms controlling circadian rhythms and indicate that the role of the IGL varies across species with no apparent relationship between diurnality-nocturnality and circadian function.
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Affiliation(s)
- N Goel
- Department of Psychology, 207 High Street, Judd Hall, Wesleyan University, Middletown, CT 06459, USA.
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47
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Nonphotic entrainment by 5-HT1A/7 receptor agonists accompanied by reduced Per1 and Per2 mRNA levels in the suprachiasmatic nuclei. J Neurosci 2000. [PMID: 10908630 DOI: 10.1523/jneurosci.20-15-05867.2000] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In mammals, the environmental light/dark cycle strongly synchronizes the circadian clock within the suprachiasmatic nuclei (SCN) to 24 hr. It is well known that not only photic but also nonphotic stimuli can entrain the SCN clock. Actually, many studies have shown that a daytime injection of 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH DPAT), a serotonin 1A/7 receptor agonist, as a nonphotic stimulus induces phase advances in hamster behavioral circadian rhythms in vivo, as well as the neuron activity rhythm of the SCN in vitro. Recent reports suggest that mammalian homologs of the Drosophila clock gene, Period (Per), are involved in photic entrainment. Therefore, we examined whether phase advances elicited by 8-OH DPAT were associated with a change of Period mRNA levels in the SCN. In this experiment, we cloned partial cDNAs encoding hamster Per1, Per2, and Per3 and observed both circadian oscillation and the light responsiveness of Period. Furthermore, we found that the inhibitory effect of 8-OH DPAT on hamster Per1 and Per2 mRNA levels in the SCN occurred only during the hamster's mid-subjective day, but not during the early subjective day or subjective night. The present findings demonstrate that the acute and circadian time-dependent reduction of Per1 and/or Per2 mRNA in the hamster SCN by 8-OH DPAT is strongly correlated with the phase resetting in response to 8-OH DPAT.
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van Esseveldt KE, Lehman MN, Boer GJ. The suprachiasmatic nucleus and the circadian time-keeping system revisited. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2000; 33:34-77. [PMID: 10967353 DOI: 10.1016/s0165-0173(00)00025-4] [Citation(s) in RCA: 212] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Many physiological and behavioral processes show circadian rhythms which are generated by an internal time-keeping system, the biological clock. In rodents, evidence from a variety of studies has shown the suprachiasmatic nucleus (SCN) to be the site of the master pacemaker controlling circadian rhythms. The clock of the SCN oscillates with a near 24-h period but is entrained to solar day/night rhythm by light. Much progress has been made recently in understanding the mechanisms of the circadian system of the SCN, its inputs for entrainment and its outputs for transfer of the rhythm to the rest of the brain. The present review summarizes these new developments concerning the properties of the SCN and the mechanisms of circadian time-keeping. First, we will summarize data concerning the anatomical and physiological organization of the SCN, including the roles of SCN neuropeptide/neurotransmitter systems, and our current knowledge of SCN input and output pathways. Second, we will discuss SCN transplantation studies and how they have contributed to knowledge of the intrinsic properties of the SCN, communication between the SCN and its targets, and age-related changes in the circadian system. Third, recent findings concerning the genes and molecules involved in the intrinsic pacemaker mechanisms of insect and mammalian clocks will be reviewed. Finally, we will discuss exciting new possibilities concerning the use of viral vector-mediated gene transfer as an approach to investigate mechanisms of circadian time-keeping.
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Affiliation(s)
- K E van Esseveldt
- Graduate School Neurosciences Amsterdam, Netherlands Institute for Brain Research, Meibergdreef 33, 1105 AZ ZO, Amsterdam, The Netherlands
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Pevet P, Jacob N, Vuillez P. Suprachiasmatic nuclei, intergeniculate leaflet, and photoperiod. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 460:233-45. [PMID: 10810519 DOI: 10.1007/0-306-46814-x_26] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- P Pevet
- UMR-CNRS 7518, Université L. Pasteur, Strasbourg, France.
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Harrington ME, Schak KM. Neuropeptide Y phase advances the in vitro hamster circadian clock during the subjective day with no effect on phase during the subjective night. Can J Physiol Pharmacol 2000. [DOI: 10.1139/y99-130] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mammalian daily (circadian) clock is located in the suprachiasmatic nuclei of the hypothalamus. Clock function can be detected by the measurement of the circadian change in spontaneous firing rate of suprachiasmatic nuclei cells in a brain slice preparation in vitro. We investigated the effects of neuropeptide Y on this rhythm of firing rate in hamster suprachiasmatic nuclei neurons. Slices were prepared using standard techniques. On the 1st day in vitro, neuropeptide Y (200 ng/200 nL; 47 pmol) was applied as a microdrop to the suprachiasmatic nuclei region at various times. Spontaneous single-unit firing was measured for 6-12 h on the 2nd day in vitro. Peak firing rate in treated slices was compared with that of untreated control slices to measure phase shifts induced by the peptide. Neuropeptide Y induced phase advances of circa-3h when applied during the subjective day (ZT 2-10) but did not significantly alter phase when applied during the subjective night. The phase shifts to neuropeptide Y in the hamster tissue in vitro are similar in phase dependency and magnitude to shifts measured in vivo.Key words: circadian, neuropeptide Y, rhythm, suprachiasmatic.
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