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Gegnaw ST, Sandu C, Mazzaro N, Mendoza J, Bergen AA, Felder-Schmittbuhl MP. Enhanced Robustness of the Mouse Retinal Circadian Clock Upon Inherited Retina Degeneration. J Biol Rhythms 2022; 37:567-574. [PMID: 35912966 DOI: 10.1177/07487304221112845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Daily biological rhythms are fundamental to retinal physiology and visual function. They are generated by a local circadian clock composed of a network of cell type/layer-specific, coupled oscillators. Animal models of retinal degeneration have been instrumental in characterizing the anatomical organization of the retinal clock. However, it is still unclear, among the multiple cell-types composing the retina, which ones are essential for proper circadian function. In this study, we used a previously well-characterized mouse model for autosomal dominant retinitis pigmentosa to examine the relationship between rod degeneration and the retinal circadian clock. This model carries the P23H mutation in rhodopsin, which induces mild rod degeneration in heterozygous and rapid loss of photoreceptors in homozygous genotypes. By measuring PER2::LUC bioluminescence rhythms, we show that the retinal clock in P23H/+ heterozygous mice displays circadian rhythms with significantly increased robustness and amplitude. By treating retinal explants with L-α aminoadipic acid, we further provide evidence that this enhanced rhythmicity might involve activation of Müller glial cells.
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Affiliation(s)
- Shumet T Gegnaw
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France.,Departments of Clinical Genetics and Ophthalmology, University of Amsterdam, Amsterdam UMC, AMC, Amsterdam, The Netherlands
| | - Cristina Sandu
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Nadia Mazzaro
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Jorge Mendoza
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Arthur A Bergen
- Departments of Clinical Genetics and Ophthalmology, University of Amsterdam, Amsterdam UMC, AMC, Amsterdam, The Netherlands.,The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Marie-Paule Felder-Schmittbuhl
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
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Neuronal Myocyte-Specific Enhancer Factor 2D (MEF2D) Is Required for Normal Circadian and Sleep Behavior in Mice. J Neurosci 2019; 39:7958-7967. [PMID: 31420455 DOI: 10.1523/jneurosci.0411-19.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 07/08/2019] [Accepted: 08/10/2019] [Indexed: 11/21/2022] Open
Abstract
The transcription factor, myocyte enhancer factor-2 (MEF2), is required for normal circadian behavior in Drosophila; however, its role in the mammalian circadian system has not been established. Of the four mammalian Mef2 genes, Mef2d is highly expressed in the suprachiasmatic nucleus (SCN) of the hypothalamus, a region critical for coordinating peripheral circadian clocks. Using both conventional and brain-specific Mef2d KO (Mef2d -/-) mouse lines, we demonstrate that MEF2D is essential for maintaining the length of the circadian free-running period of locomotor activity and normal sleep patterns in male mice. Crossing Mef2d -/- with Per2::luc reporter mice, we show that these behavioral changes are achieved without altering the endogenous period of the master circadian oscillator in the SCN. Together, our data suggest that alterations in behavior in Mef2d -/- mice may be the result of an effect on SCN output, rather than an effect on timekeeping within the SCN itself. These findings add to the growing body of evidence that MEF2 proteins play important roles in the brain.SIGNIFICANCE STATEMENT These studies are the first to show a role for MEF2 proteins in the brain outside of the hippocampus, and our findings suggest that these proteins may play diverse roles in the CNS. It is important to continue to build on our understanding of the roles of proteins acting in the SCN because SCN dysfunction underlies jet lag in humans and influences the response to shift work schedules, which are now known as risk factors for the development of cancer. Our work on MEF2D could be the basis for opening new lines of research in the development and regulation of circadian rhythms.
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Ba-Ali S, Brøndsted AE, Andersen HU, Sander B, Jennum PJ, Lund-Andersen H. Assessment of diurnal melatonin, cortisol, activity, and sleep-wake cycle in patients with and without diabetic retinopathy. Sleep Med 2018; 54:35-42. [PMID: 30529775 DOI: 10.1016/j.sleep.2018.10.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 09/20/2018] [Accepted: 10/02/2018] [Indexed: 12/23/2022]
Abstract
OBJECTIVE To assess the diurnal melatonin, cortisol, and activity/rest levels, as well as sleep quality, in patients with and without nonproliferative diabetic retinopathy (DR). METHODS We included 25 diabetic patients with DR and 29 without DR. A total of 21 healthy subjects constituted the control group. We assessed the circadian rhythm by actigraphy and diurnal salivary melatonin and cortisol measurements. Sleep quality was evaluated by actigraphy and the Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS) questionnaires. Light exposure was quantified by actigraphy. The primary outcome was peak salivary melatonin level. Secondary outcomes were mean melatonin and cortisol levels during dark hours, activity-rest rhythm, sleep quality, as well as level of white, red, green, and blue light exposure. RESULTS Peak melatonin concentration at 04:00 and mean nocturnal melatonin level were significantly reduced in all diabetic patients, regardless of retinopathy stage (p < 0.001). Levels of light exposures during dark hours were not significantly different in patients with and without DR and healthy controls. Only patients with DR showed increased intradaily variability in their activity-rest interval, indicating circadian misalignment (p = 0.04). Neither the objective actigraphic sleep quality parameters nor the subjective PSQI or ESS scores were significantly different between healthy controls and diabetic patients. CONCLUSIONS Reduced nocturnal melatonin concentration and increased fragmentation of activity-rest intervals revealed circadian rhythm disturbance in diabetic patients with DR.
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Affiliation(s)
- Shakoor Ba-Ali
- Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark; Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | | | | | - Birgit Sander
- Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark
| | - Poul Jørgen Jennum
- Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Danish Centre for Sleep Medicine, Neurophysiology Clinic, Rigshospitalet, Glostrup, Denmark
| | - Henrik Lund-Andersen
- Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark; Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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NMDA and PACAP receptor signaling interact to mediate retinal-induced scn cellular rhythmicity in the absence of light. PLoS One 2013; 8:e76365. [PMID: 24098484 PMCID: PMC3788112 DOI: 10.1371/journal.pone.0076365] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 08/26/2013] [Indexed: 12/19/2022] Open
Abstract
The "core" region of the suprachiasmatic nucleus (SCN), a central clock responsible for coordinating circadian rhythms, shows a daily rhythm in phosphorylation of extracellular regulated kinase (pERK). This cellular rhythm persists under constant darkness and, despite the absence of light, is dependent upon inputs from the eye. The neural signals driving this rhythmicity remain unknown and here the roles of glutamate and PACAP are examined. First, rhythmic phosphorylation of the NR1 NMDA receptor subunit (pNR1, a marker for receptor activation) was shown to coincide with SCN core pERK, with a peak at circadian time (CT) 16. Enucleation and intraocular TTX administration attenuated the peak in the pERK and pNR1 rhythms, demonstrating that activation of the NMDA receptor and ERK in the SCN core at CT16 are dependent on retinal inputs. In contrast, ERK and NR1 phosphorylation in the SCN shell region were unaffected by these treatments. Intraventricular administration of the NMDA receptor antagonist MK-801 also attenuated the peak in SCN core pERK, indicating that ERK phosphorylation in this region requires NMDA receptor activation. As PACAP is implicated in photic entrainment and is known to modulate glutamate signaling, the effects of a PAC1 receptor antagonist (PACAP 6-38) on SCN core pERK and pNR1 also were examined. PACAP 6-38 administration attenuated SCN core pERK and pNR1, suggesting that PACAP induces pERK directly, and indirectly via a modulation of NMDA receptor signaling. Together, these data indicate that, in the absence of light, retinal-mediated NMDA and PAC1 receptor activation interact to induce cellular rhythms in the SCN core. These results highlight a novel function for glutamate and PACAP release in the hamster SCN apart from their well-known roles in the induction of photic circadian clock resetting.
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Reiter R, Tan D, SanchezBarcelo E, Mediavilla M, Gitto E, Korkmaz A. Circadian mechanisms in the regulation of melatonin synthesis: disruption with light at night and the pathophysiological consequences. ACTA ACUST UNITED AC 2011. [DOI: 10.5455/jeim.101210.ir.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Abstract
Life on earth is subject to alternating cycles of day and night imposed by the rotation of the earth. Consequently, living things have evolved photodetective systems to synchronize their physiology and behavior with the external light-dark cycle. This form of photodetection is unlike the familiar "image vision," in that the basic information is light or darkness over time, independent of spatial patterns. "Nonimage" vision is probably far more ancient than image vision and is widespread in living species. For mammals, it has long been assumed that the photoreceptors for nonimage vision are also the textbook rods and cones. However, recent years have witnessed the discovery of a small population of retinal ganglion cells in the mammalian eye that express a unique visual pigment called melanopsin. These ganglion cells are intrinsically photosensitive and drive a variety of nonimage visual functions. In addition to being photoreceptors themselves, they also constitute the major conduit for rod and cone signals to the brain for nonimage visual functions such as circadian photoentrainment and the pupillary light reflex. Here we review what is known about these novel mammalian photoreceptors.
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Affiliation(s)
- Michael Tri Hoang Do
- Solomon H. Snyder Department of Neuroscience and Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA
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Abstract
Mammalian circadian rhythms are controlled by endogenous biological oscillators, including a master clock located in the hypothalamic suprachiasmatic nuclei (SCN). Since the period of this oscillation is of approximately 24 h, to keep synchrony with the environment, circadian rhythms need to be entrained daily by means of Zeitgeber ("time giver") signals, such as the light-dark cycle. Recent advances in the neurophysiology and molecular biology of circadian rhythmicity allow a better understanding of synchronization. In this review we cover several aspects of the mechanisms for photic entrainment of mammalian circadian rhythms, including retinal sensitivity to light by means of novel photopigments as well as circadian variations in the retina that contribute to the regulation of retinal physiology. Downstream from the retina, we examine retinohypothalamic communication through neurotransmitter (glutamate, aspartate, pituitary adenylate cyclase-activating polypeptide) interaction with SCN receptors and the resulting signal transduction pathways in suprachiasmatic neurons, as well as putative neuron-glia interactions. Finally, we describe and analyze clock gene expression and its importance in entrainment mechanisms, as well as circadian disorders or retinal diseases related to entrainment deficits, including experimental and clinical treatments.
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Affiliation(s)
- Diego A Golombek
- Laboratory of Chronobiology, Department of Science and Technology, University of Quilmes/Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Quilmes, Argentina.
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Rovsing L, Rath MF, Lund-Andersen C, Klein DC, Møller M. A neuroanatomical and physiological study of the non-image forming visual system of the cone-rod homeobox gene (Crx) knock out mouse. Brain Res 2010; 1343:54-65. [PMID: 20438719 PMCID: PMC3652412 DOI: 10.1016/j.brainres.2010.04.066] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 04/13/2010] [Accepted: 04/14/2010] [Indexed: 11/18/2022]
Abstract
The anatomy and physiology of the non-image forming visual system was investigated in a visually blind cone-rod homeobox gene (Crx) knock-out mouse (Crx(-)(/)(-)), which lacks the outer segments of the photoreceptors. We show that the suprachiasmatic nuclei (SCN) in the Crx(-/-) mouse exhibit morphology as in the wild type mouse. In addition, the SCN contain vasoactive intestinal peptide-, vasopressin-, and gastrin-releasing peptide-immunoreactive neurons as present in the wild type. Anterograde in vivo tracings from the retina of the Crx(-/-) and wild type mouse showed that the retinohypothalamic projection to the SCN and the central optic pathways were similar in both animals. Telemetric monitoring of the running activity and temperature revealed that both the Crx(-/-)and wild type mouse exhibited diurnal rhythms with a 24-h period, which could be phase changed by light. However, power spectral analysis revealed that both rhythms in the Crx(-/-) mouse were less robust than those in the wild type. The normal development of the SCN and the central visual pathways in the Crx(-/-) mouse suggests that a modulatory input from the photoreceptors in the peripheral retina to the retinal melanopsin neurons or the SCN may be necessary for a normal function of the non-image forming system of the mouse. However, a change in the SCN of the Crx(-/-) mouse might also explain the observed circadian differences between the knock out mouse and wild type mouse.
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Affiliation(s)
- Louise Rovsing
- Department of Neuroscience and Pharmacology, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Martin F. Rath
- Department of Neuroscience and Pharmacology, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Casper Lund-Andersen
- Department of Neuroscience and Pharmacology, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - David C. Klein
- Section on Neuroendocrinology, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Morten Møller
- Department of Neuroscience and Pharmacology, Panum Institute, University of Copenhagen, Copenhagen, Denmark
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Ruggiero L, Allen CN, Brown RL, Robinson DW. Mice with early retinal degeneration show differences in neuropeptide expression in the suprachiasmatic nucleus. Behav Brain Funct 2010; 6:36. [PMID: 20604961 PMCID: PMC2912232 DOI: 10.1186/1744-9081-6-36] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Accepted: 07/06/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In mammals, the brain clock responsible for generating circadian rhythms is located in the suprachiasmatic nucleus (SCN) of the hypothalamus. Light entrainment of the clock occurs through intrinsically photosensitive retinal ganglion cells (ipRGCs) whose axons project to the SCN via the retinohypothalamic tract. Although ipRGCs are sufficient for photoentrainment, rod and cone photoreceptors also contribute. Adult CBA/J mice, which exhibit loss of rod and cone photoreceptors during early postnatal development, have greater numbers of ipRGCs compared to CBA/N control mice. A greater number of photosensitive cells might argue for enhanced light responses, however, these mice exhibit attenuated phase shifting behaviors. To reconcile these findings, we looked for potential differences in SCN neurons of CBA/J mice that might underly the altered circadian behaviors. We hypothesized that CBA/J mice have differences in the expression of neuropeptides in the SCN, where ipRGCs synapse. The neuropeptides vasoactive intestinal peptide (VIP) and vasopressin (VP) are expressed by many SCN neurons and play an important role in the generation of circadian rhythms and photic entrainment. METHODS Using immunohistochemistry, we looked for differences in the expression of VIP and VP in the SCN of CBA/J mice, and using a light-induced FOS assay, we also examined the degree of retinal innervation of the SCN by ipRGCs. RESULTS Our data demonstrate greater numbers of VIP-and VP-positive cells in the SCN of CBA/J mice and a greater degree of light-induced FOS expression. CONCLUSIONS These results implicate changes in neuropeptide expression in the SCN which may underlie the altered circadian responses to light in these animals.
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Affiliation(s)
- Linda Ruggiero
- Center for Research on Occupational and Environmental Toxicology, Oregon Health & Science University, Portland 97239, USA
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Abstract
The circadian clock is an evolutionarily, highly conserved feature of most organisms. This internal timing mechanism coordinates biochemical, physiological and behavioral processes to maintain synchrony with the environmental cycles of light, temperature and nutrients. Several studies have shown that light is the most potent cue used by most organisms (humans included) to synchronize daily activities. In mammals, light perception occurs only in the retina; three different types of photoreceptors are present within this tissue: cones, rods and the newly discovered intrinsically photosensitive retinal ganglion cells (ipRGCs). Researchers believe that the classical photoreceptors (e.g., the rods and the cones) are responsible for the image-forming vision, whereas the ipRGCs play a key role in the non-image forming vision. This non-image-forming photoreceptive system communicates not only with the master circadian pacemaker located in the suprachiasmatic nuclei of the hypothalamus, but also with many other brain areas that are known to be involved in the regulation of several functions; thus, this non-image forming system may also affect several aspects of mammalian health independently from the circadian system.
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Affiliation(s)
- Ketema N Paul
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
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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: 5.1] [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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Ruggiero L, Allen CN, Brown RL, Robinson DW. The development of melanopsin-containing retinal ganglion cells in mice with early retinal degeneration. Eur J Neurosci 2009; 29:359-67. [PMID: 19200239 PMCID: PMC2764118 DOI: 10.1111/j.1460-9568.2008.06589.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
In mammals, the neuronal pathways by which rod and cone photoreceptors mediate vision have been well documented. The roles that classical photoreceptors play in photoentrainment, however, have been less clear. In mammals, intrinsically photosensitive retinal ganglion cells (ipRGCs) that express the photopigment melanopsin project directly to the suprachiasmatic nucleus of the hypothalamus, the site of the circadian clock, and thereby contribute to non-image-forming responses to light. Classical photoreceptors are not necessary for photoentrainment as loss of rods and cones does not eliminate light entrainment. Conflicting evidence arose, however, when attenuated phase-shifting responses were observed in the retinal-degenerate CBA/J mouse. In this study, we examined the time course of retinal degeneration in CBA/J mice and used these animals to determine if maturation of the outer retina regulates the morphology, number and distribution of ipRGCs. We also examined whether degeneration during the early development of the outer retina can alter the function of the adult circadian system. We report that dendritic stratification and distribution of ipRGCs was unaltered in mice with early retinal degeneration, suggesting that normal development of the outer retina was not necessary for these processes. We found, however, that adult CBA/J mice have greater numbers of ipRGCs than controls, implicating a role for the outer retinal photoreceptors in regulating developmental cell death of ipRGCs.
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Affiliation(s)
- Linda Ruggiero
- Center for Research on Occupational and Environmental Toxicology, L606, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland OR 97239, USA
- Neuroscience Graduate Program
| | - Charles N. Allen
- Center for Research on Occupational and Environmental Toxicology, L606, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland OR 97239, USA
| | - R. Lane Brown
- Department of Veterinary & Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, WA 99164 USA
| | - David W. Robinson
- Center for Research on Occupational and Environmental Toxicology, L606, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland OR 97239, USA
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Abstract
Daily rhythms are a ubiquitous feature of living systems. Generally, these rhythms are not just passive consequences of cyclic fluctuations in the environment, but instead originate within the organism. In mammals, including humans, the master pacemaker controlling 24-hour rhythms is localized in the suprachiasmatic nuclei of the hypothalamus. This circadian clock is responsible for the temporal organization of a wide variety of functions, ranging from sleep and food intake, to physiological measures such as body temperature, heart rate and hormone release. The retinal circadian clock was the first extra-SCN circadian oscillator to be discovered in mammals and several studies have now demonstrated that many of the physiological, cellular and molecular rhythms that are present within the retina are under the control of a retinal circadian clock, or more likely a network of hierarchically organized circadian clocks that are present within this tissue. BioEssays 30:624-633, 2008. (c) 2008 Wiley Periodicals, Inc.
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Affiliation(s)
- Gianluca Tosini
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute. Morehouse School of Medicine, Atlanta, GA, USA.
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