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Liao M, Gao X, Chen C, Li Q, Guo Q, Huang H, Zhang E, Ju D. Integrated neural tracing and in-situ barcoded sequencing reveals the logic of SCN efferent circuits in regulating circadian behaviors. SCIENCE CHINA. LIFE SCIENCES 2024; 67:518-528. [PMID: 38057622 DOI: 10.1007/s11427-023-2420-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 06/30/2023] [Indexed: 12/08/2023]
Abstract
The circadian clock coordinates rhythms in numerous physiological processes to maintain organismal homeostasis. Since the suprachiasmatic nucleus (SCN) is widely accepted as the circadian pacemaker, it is critical to understand the neural mechanisms by which rhythmic information is transferred from the SCN to peripheral clocks. Here, we present the first comprehensive map of SCN efferent connections and suggest a molecular logic underlying these projections. The SCN projects broadly to most major regions of the brain, rather than solely to the hypothalamus and thalamus. The efferent projections from different subtypes of SCN neurons vary in distance and intensity, and blocking synaptic transmission of these circuits affects circadian rhythms in locomotion and feeding to different extents. We also developed a barcoding system to integrate retrograde tracing with in-situ sequencing, allowing us to link circuit anatomy and spatial patterns of gene expression. Analyses using this system revealed that brain regions functioning downstream of the SCN receive input from multiple neuropeptidergic cell types within the SCN, and that individual SCN neurons generally project to a single downstream brain region. This map of SCN efferent connections provides a critical foundation for future investigations into the neural circuits underlying SCN-mediated rhythms in physiology. Further, our new barcoded tracing method provides a tool for revealing the molecular logic of neuronal circuits within heterogeneous brain regions.
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Affiliation(s)
- Meimei Liao
- College of Biological Sciences, China Agriculture University, Beijing, 100193, China
- National Institute of Biological Sciences (NIBS), Beijing, 102206, China
| | - Xinwei Gao
- Chinese Institute for Brain Research, Beijing, 102206, China
| | - Chen Chen
- National Institute of Biological Sciences (NIBS), Beijing, 102206, China
| | - Qi Li
- National Institute of Biological Sciences (NIBS), Beijing, 102206, China
- Tsinghua Institute of Multidisciplinar^ Biomedical Research, Tsinghua University, Beijing, 102206, China
| | - Qingchun Guo
- Chinese Institute for Brain Research, Beijing, 102206, China
- School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China
| | - He Huang
- Department of Anesthesiology, The Second Affiliated Hospital, Chongqing Medical University, Chongqing, 401336, China
| | - Erquan Zhang
- National Institute of Biological Sciences (NIBS), Beijing, 102206, China
- Tsinghua Institute of Multidisciplinar^ Biomedical Research, Tsinghua University, Beijing, 102206, China
| | - Dapeng Ju
- Department of Anesthesiology, The Second Affiliated Hospital, Chongqing Medical University, Chongqing, 401336, China.
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Lee J, Chen S, Monfared RV, Derdeyn P, Leong K, Chang T, Beier K, Baldi P, Alachkar A. Reanalysis of primate brain circadian transcriptomics reveals connectivity-related oscillations. iScience 2023; 26:107810. [PMID: 37752952 PMCID: PMC10518731 DOI: 10.1016/j.isci.2023.107810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 07/22/2023] [Accepted: 08/30/2023] [Indexed: 09/28/2023] Open
Abstract
Research shows that brain circuits controlling vital physiological processes are closely linked with endogenous time-keeping systems. In this study, we aimed to examine oscillatory gene expression patterns of well-characterized neuronal circuits by reanalyzing publicly available transcriptomic data from a spatiotemporal gene expression atlas of a non-human primate. Unexpectedly, brain structures known for regulating circadian processes (e.g., hypothalamic nuclei) did not exhibit robust cycling expression. In contrast, basal ganglia nuclei, not typically associated with circadian physiology, displayed the most dynamic cycling behavior of its genes marked by sharp temporally defined expression peaks. Intriguingly, the mammillary bodies, considered hypothalamic nuclei, exhibited gene expression patterns resembling the basal ganglia, prompting reevaluation of their classification. Our results emphasize the potential for high throughput circadian gene expression analysis to deepen our understanding of the functional synchronization across brain structures that influence physiological processes and resulting complex behaviors.
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Affiliation(s)
- Justine Lee
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, USA
| | - Siwei Chen
- Department of Computer Science, School of Information and Computer Sciences, University of California, Irvine, Irvine, CA, USA
| | - Roudabeh Vakil Monfared
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, USA
| | - Pieter Derdeyn
- Mathematical, Computational, and Systems Biology Program, University of California, Irvine, Irvine, CA, USA
| | - Kenneth Leong
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, USA
| | - Tiffany Chang
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, USA
| | - Kevin Beier
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, USA
- Department of Physiology and Biophysics, School of medicine, University of California, Irvine, Irvine, CA, USA
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA 92697-4560, USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697-4560, USA
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA 92697, USA
| | - Pierre Baldi
- Department of Computer Science, School of Information and Computer Sciences, University of California, Irvine, Irvine, CA, USA
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA 92697, USA
- Institute for Genomics and Bioinformatics, University of California, Irvine, Irvine, CA, USA
| | - Amal Alachkar
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, USA
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA 92697, USA
- Institute for Genomics and Bioinformatics, University of California, Irvine, Irvine, CA, USA
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Davidson AJ, Beckner D, Bonnefont X. A Journey in the Brain's Clock: In Vivo Veritas? BIOLOGY 2023; 12:1136. [PMID: 37627020 PMCID: PMC10452196 DOI: 10.3390/biology12081136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 08/12/2023] [Accepted: 08/14/2023] [Indexed: 08/27/2023]
Abstract
The suprachiasmatic nuclei (SCN) of the hypothalamus contain the circadian pacemaker that coordinates mammalian rhythms in tune with the day-night cycle. Understanding the determinants of the intrinsic rhythmicity of this biological clock, its outputs, and resetting by environmental cues, has been a longstanding goal of the field. Integrated techniques of neurophysiology, including lesion studies and in vivo multi-unit electrophysiology, have been key to characterizing the rhythmic nature and outputs of the SCN in animal models. In parallel, reduced ex vivo and in vitro approaches have permitted us to unravel molecular, cellular, and multicellular mechanisms underlying the pacemaker properties of the SCN. New questions have emerged in recent years that will require combining investigation at a cell resolution within the physiological context of the living animal: What is the role of specific cell subpopulations in the SCN neural network? How do they integrate various external and internal inputs? What are the circuits involved in controlling other body rhythms? Here, we review what we have already learned about the SCN from in vivo studies, and how the recent development of new genetically encoded tools and cutting-edge imaging technology in neuroscience offers chronobiologists the opportunity to meet these challenges.
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Affiliation(s)
- Alec J. Davidson
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA;
| | - Delaney Beckner
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA;
| | - Xavier Bonnefont
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094 Montpellier, France
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Santana NNM, Silva EHA, dos Santos SF, Costa MSMO, Nascimento Junior ES, Engelberth RCJG, Cavalcante JS. Retinorecipient areas in the common marmoset ( Callithrix jacchus): An image-forming and non-image forming circuitry. Front Neural Circuits 2023; 17:1088686. [PMID: 36817647 PMCID: PMC9932520 DOI: 10.3389/fncir.2023.1088686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 01/10/2023] [Indexed: 02/05/2023] Open
Abstract
The mammalian retina captures a multitude of diverse features from the external environment and conveys them via the optic nerve to a myriad of retinorecipient nuclei. Understanding how retinal signals act in distinct brain functions is one of the most central and established goals of neuroscience. Using the common marmoset (Callithrix jacchus), a monkey from Northeastern Brazil, as an animal model for parsing how retinal innervation works in the brain, started decades ago due to their marmoset's small bodies, rapid reproduction rate, and brain features. In the course of that research, a large amount of new and sophisticated neuroanatomical techniques was developed and employed to explain retinal connectivity. As a consequence, image and non-image-forming regions, functions, and pathways, as well as retinal cell types were described. Image-forming circuits give rise directly to vision, while the non-image-forming territories support circadian physiological processes, although part of their functional significance is uncertain. Here, we reviewed the current state of knowledge concerning retinal circuitry in marmosets from neuroanatomical investigations. We have also highlighted the aspects of marmoset retinal circuitry that remain obscure, in addition, to identify what further research is needed to better understand the connections and functions of retinorecipient structures.
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Affiliation(s)
- Nelyane Nayara M. Santana
- Laboratory of Neurochemical Studies, Department of Physiology and Behavior, Bioscience Center, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Eryck H. A. Silva
- Laboratory of Neurochemical Studies, Department of Physiology and Behavior, Bioscience Center, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Sâmarah F. dos Santos
- Laboratory of Neurochemical Studies, Department of Physiology and Behavior, Bioscience Center, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Miriam S. M. O. Costa
- Laboratory of Neuroanatomy, Department of Morphology, Bioscience Center, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Expedito S. Nascimento Junior
- Laboratory of Neuroanatomy, Department of Morphology, Bioscience Center, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Rovena Clara J. G. Engelberth
- Laboratory of Neurochemical Studies, Department of Physiology and Behavior, Bioscience Center, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Jeferson S. Cavalcante
- Laboratory of Neurochemical Studies, Department of Physiology and Behavior, Bioscience Center, Federal University of Rio Grande do Norte, Natal, Brazil,*Correspondence: Jeferson S. Cavalcante,
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The duper mutation reveals previously unsuspected functions of Cryptochrome 1 in circadian entrainment and heart disease. Proc Natl Acad Sci U S A 2022; 119:e2121883119. [PMID: 35930669 PMCID: PMC9371649 DOI: 10.1073/pnas.2121883119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The Cryptochrome 1 (Cry1)-deficient duper mutant hamster has a short free-running period in constant darkness (τDD) and shows large phase shifts in response to brief light pulses. We tested whether this measure of the lability of the circadian phase is a general characteristic of Cry1-null animals and whether it indicates resistance to jet lag. Upon advance of the light:dark (LD) cycle, both duper hamsters and Cry1-/- mice re-entrained locomotor rhythms three times as fast as wild types. However, accelerated re-entrainment was dissociated from the amplified phase-response curve (PRC): unlike duper hamsters, Cry1-/- mice show no amplification of the phase response to 15' light pulses. Neither the amplified acute shifts nor the increased rate of re-entrainment in duper mutants is due to acceleration of the circadian clock: when mutants drank heavy water to lengthen the period, these aspects of the phenotype persisted. In light of the health consequences of circadian misalignment, we examined effects of duper and phase shifts on a hamster model of heart disease previously shown to be aggravated by repeated phase shifts. The mutation shortened the lifespan of cardiomyopathic hamsters relative to wild types, but this effect was eliminated when mutants experienced 8-h phase shifts every second week, to which they rapidly re-entrained. Our results reveal previously unsuspected roles of Cry1 in phase shifting and longevity in the face of heart disease. The duper mutant offers new opportunities to understand the basis of circadian disruption and jet lag.
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Goltsev AV, Wright EAP, Mendes JFF, Yoon S. Generation and Disruption of Circadian Rhythms in the Suprachiasmatic Nucleus: A Core-Shell Model. J Biol Rhythms 2022; 37:545-561. [PMID: 35848398 PMCID: PMC9452856 DOI: 10.1177/07487304221107834] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We focus our research on how the core-shell organization controls behavior of the
suprachiasmatic nucleus (SCN), how the core and shell are synchronized to the
environment, what impact they have on the behavior of the SCN under different
lighting conditions, and what mechanisms disrupt synchronization. To this end,
we use a reduced Kuramoto model, with parameters inferred from experimental
observations and calibrated for mice, and perform a detailed comparison between
the model and experimental data under light-dark (LD), dark-dark (DD), and
light-light (LL) conditions. The operating limits of free-running and entrained
SCN activity under symmetric LD cycles are analyzed, with particular focus on
the phenomena of anticipation and dissociation. Results reveal that the
core-shell organization of the SCN enables anticipation of future events over
circadian cycles. The model predicts the emergence of a second (dissociated)
rhythm for large and small LD periods. Our results are in good qualitative and
quantitative agreement with experimental observations of circadian dissociation.
We further describe SCN activity under LL conditions and show that our model
satisfies Aschoff’s first rule, according to which the endogenous free-running
circadian period observed under complete darkness will shorten in diurnal
animals and lengthen in nocturnal animals under constant light. Our results
strongly suggest that the Kuramoto model captures essential features of
synchronization and entrainment in the SCN. Moreover, our approach is easily
extendible to an arbitrary number of groups, with dynamics described by explicit
equations for the group phase and synchronization index. Viewed together, the
reduced Kuramoto model presents itself as a useful tool for exploring open
problems in the study of circadian rhythms, one that can account for evolving
views of the circadian system’s organization, including peripheral clocks and
inter-hemispheric interaction, and can be translated to other nocturnal and
diurnal animals, including humans.
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Affiliation(s)
| | - Edgar A P Wright
- Department of Physics & I3N, University of Aveiro, Aveiro, Portugal
| | - José F F Mendes
- Department of Physics & I3N, University of Aveiro, Aveiro, Portugal
| | - Sooyeon Yoon
- Department of Physics & I3N, University of Aveiro, Aveiro, Portugal
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Circadian Regulation of Retinal Pigment Epithelium Function. Int J Mol Sci 2022; 23:ijms23052699. [PMID: 35269840 PMCID: PMC8910459 DOI: 10.3390/ijms23052699] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/16/2022] [Accepted: 02/21/2022] [Indexed: 12/22/2022] Open
Abstract
The retinal pigment epithelium (RPE) is a single layer of cells located between the choriocapillaris vessels and the light-sensitive photoreceptors in the outer retina. The RPE performs physiological processes necessary for the maintenance and support of photoreceptors and visual function. Among the many functions performed by the RPE, the timing of the peak in phagocytic activity by the RPE of the photoreceptor outer segments that occurs 1-2 h. after the onset of light has captured the interest of many investigators and has thus been intensively studied. Several studies have shown that this burst in phagocytic activity by the RPE is under circadian control and is present in nocturnal and diurnal species and rod and cone photoreceptors. Previous investigations have demonstrated that a functional circadian clock exists within multiple retinal cell types and RPE cells. However, the anatomical location of the circadian controlling this activity is not clear. Experimental evidence indicates that the circadian clock, melatonin, dopamine, and integrin signaling play a key role in controlling this rhythm. A series of very recent studies report that the circadian clock in the RPE controls the daily peak in phagocytic activity. However, the loss of the burst in phagocytic activity after light onset does not result in photoreceptor or RPE deterioration during aging. In the current review, we summarized the current knowledge on the mechanism controlling this phenomenon and the physiological role of this peak.
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8
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Tabibzadeh S. CircadiOmic medicine and aging. Ageing Res Rev 2021; 71:101424. [PMID: 34389481 DOI: 10.1016/j.arr.2021.101424] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 07/22/2021] [Accepted: 08/05/2021] [Indexed: 01/15/2023]
Abstract
The earth displays daily, seasonal and annual environmental cycles that have led to evolutionarily adapted ultradian, circadian and infradian rhythmicities in the entire biosphere. All biological organisms must adapt to these cycles that synchronize the function of their circadiome. The objective of this review is to discuss the latest knowledge regarding the role of circadiomics in health and aging. The biological timekeepers are responsive to the environmental cues at microsecond to seasonal time-scales and act with precision of a clock machinery. The robustness of these rhythms is essential to normal daily function of cells, tissues and organs. Mis-alignment of circadian rhythms makes the individual prone to aging, sleep disorders, cancer, diabetes, and neuro-degenerative diseases. Circadian and CircadiOmic medicine are emerging fields that leverage our in-depth understanding of health issues, that arise as a result of disturbances in circadian rhythms, towards establishing better therapeutic approaches in personalized medicine and for geroprotection.
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Affiliation(s)
- Siamak Tabibzadeh
- Frontiers in Bioscience Research Institute in Aging and Cancer, 16471 Scientific Way, Irvine, CA 92618, United States.
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Faltraco F, Palm D, Coogan A, Simon F, Tucha O, Thome J. Molecular Link between Circadian Rhythmicity and Mood Disorders. Curr Med Chem 2021; 29:5692-5709. [PMID: 34620057 DOI: 10.2174/0929867328666211007113725] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 08/17/2021] [Accepted: 08/26/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND The internal clock is driven by circadian genes [e.g., Clock, Bmal1, Per1-3, Cry1-2], hormones [e.g., melatonin, cortisol], as well as zeitgeber ['synchronisers']. Chronic disturbances in the circadian rhythm in patients diagnosed with mood disorders have been recognised for more than 50 years. OBJECTIVES The aim of this review is to summarise the current knowledge and literature regarding circadian rhythms in the context of mood disorders, focussing on the role of circadian genes, hormones, and neurotransmitters. METHOD The review presents the current knowledge and literature regarding circadian rhythms in mood disorders using the Pubmed database. Articles with a focus on circadian rhythms and mood disorders [n=123], particularly from 1973 to 2020, were included. RESULTS The article suggests a molecular link between disruptions in the circadian rhythm and mood disorders. Circadian disturbances, caused by the dysregulation of circadian genes, hormones, and neurotransmitters, often result in a clinical picture resembling depression. CONCLUSION Circadian rhythms are intrinsically linked to affective disorders, such as unipolar depression and bipolar disorder.
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Affiliation(s)
- Frank Faltraco
- Department of Psychiatry and Psychotherapy, University Medical Center Rostock, Rostock. Germany
| | - Denise Palm
- Department of Psychiatry and Psychotherapy, University Medical Center Rostock, Rostock. Germany
| | - Andrew Coogan
- Department of Psychology, Maynooth University, National University of Ireland, Maynooth. Ireland
| | - Frederick Simon
- Department of Psychiatry and Psychotherapy, University Medical Center Rostock, Rostock. Germany
| | - Oliver Tucha
- Department of Psychiatry and Psychotherapy, University Medical Center Rostock, Rostock. Germany
| | - Johannes Thome
- Department of Psychiatry and Psychotherapy, University Medical Center Rostock, Rostock. Germany
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Dim light in the evening causes coordinated realignment of circadian rhythms, sleep, and short-term memory. Proc Natl Acad Sci U S A 2021; 118:2101591118. [PMID: 34556572 PMCID: PMC8488663 DOI: 10.1073/pnas.2101591118] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2021] [Indexed: 12/28/2022] Open
Abstract
In modern societies, people are regularly exposed to artificial light (e.g., light-emitting electronic devices). Dim light in the evening (DLE) imposes an artificial extension of the solar day, increasing our alertness before bedtime, delaying melatonin timing and sleep onset, and increasing sleepiness in the next morning. Using laboratory mice as a model organism, we show that 2 wk of 4-h, 20-lux DLE postpones rest–activity rhythms, delays molecular rhythms in the brain and body, and reverses the diurnal pattern of short-term memory performance. These results highlight the biological impact of DLE and emphasize the need to optimize our evening light exposure if we are to avoid shifting our biological clocks. Light provides the primary signal for entraining circadian rhythms to the day/night cycle. In addition to rods and cones, the retina contains a small population of photosensitive retinal ganglion cells (pRGCs) expressing the photopigment melanopsin (OPN4). Concerns have been raised that exposure to dim artificial lighting in the evening (DLE) may perturb circadian rhythms and sleep patterns, and OPN4 is presumed to mediate these effects. Here, we examine the effects of 4-h, 20-lux DLE on circadian physiology and behavior in mice and the role of OPN4 in these responses. We show that 2 wk of DLE induces a phase delay of ∼2 to 3 h in mice, comparable to that reported in humans. DLE-induced phase shifts are unaffected in Opn4−/− mice, indicating that rods and cones are capable of driving these responses in the absence of melanopsin. DLE delays molecular clock rhythms in the heart, liver, adrenal gland, and dorsal hippocampus. It also reverses short-term recognition memory performance, which is associated with changes in preceding sleep history. In addition, DLE modifies patterns of hypothalamic and cortical cFos signals, a molecular correlate of recent neuronal activity. Together, our data show that DLE causes coordinated realignment of circadian rhythms, sleep patterns, and short-term memory process in mice. These effects are particularly relevant as DLE conditions―due to artificial light exposure―are experienced by the majority of the populace on a daily basis.
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Saad L, Kalsbeek A, Zwiller J, Anglard P. Rhythmic Regulation of DNA Methylation Factors and Core-Clock Genes in Brain Structures Activated by Cocaine or Sucrose: Potential Role of Chromatin Remodeling. Genes (Basel) 2021; 12:genes12081195. [PMID: 34440369 PMCID: PMC8392220 DOI: 10.3390/genes12081195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 12/25/2022] Open
Abstract
The circadian system interacts with the mesocorticolimbic reward system to modulate reward and memory in a time-of-day dependent manner. The circadian discrimination of reward, however, remains difficult to address between natural reinforcers and drugs of abuse. Circadian rhythms control cocaine sensitization and conversely cocaine causes long-term alteration in circadian periodicity in part through the serotonergic neurotransmission. Since neural circuits activated by cocaine and natural reinforcers do not completely overlap, we compared the effect of cocaine with that of sucrose, a strong reinforcer in rodents, by using passive chronic administration. The expression of fifteen genes playing a major role in DNA methylation (Dnmts, Tets), circadian rhythms (Clock, Bmal1, Per1/2, Cry1/2, Rev-Erbβ, Dbp1), appetite, and satiety (Orexin, Npy) was analyzed in dopamine projection areas like the prefrontal cortex, the caudate putamen, and the hypothalamus interconnected with the reward system. The corresponding proteins of two genes (Orexin, Per2) were examined by IHC. For many factors controlling biological and cognitive functions, striking opposite responses were found between the two reinforcers, notably for genes controlling DNA methylation/demethylation processes and in global DNA methylation involved in chromatin remodeling. The data are consistent with a repression of critical core-clock genes by cocaine, suggesting that, consequently, both agents differentially modulate day/night cycles. Whether observed cocaine and sucrose-induced changes in DNA methylation in a time dependent manner are long lasting or contribute to the establishment of addiction requires further neuroepigenetic investigation. Understanding the mechanisms dissociating drugs of abuse from natural reinforcers remains a prerequisite for the design of selective therapeutic tools for compulsive behaviors.
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Affiliation(s)
- Lamis Saad
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), UMR 7364 CNRS, Université de Strasbourg, Neuropôle de Strasbourg, 67000 Strasbourg, France; (L.S.); (J.Z.)
- The Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, The Netherlands
- Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, 1066 EA Amsterdam, The Netherlands
| | - Andries Kalsbeek
- The Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, The Netherlands
- Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, 1066 EA Amsterdam, The Netherlands
- Correspondence: (A.K.); or (P.A.)
| | - Jean Zwiller
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), UMR 7364 CNRS, Université de Strasbourg, Neuropôle de Strasbourg, 67000 Strasbourg, France; (L.S.); (J.Z.)
- CNRS, Centre National de la Recherche Scientifique, 75016 Paris, France
| | - Patrick Anglard
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), UMR 7364 CNRS, Université de Strasbourg, Neuropôle de Strasbourg, 67000 Strasbourg, France; (L.S.); (J.Z.)
- INSERM, Institut National de la Santé et de la Recherche Médicale, 75013 Paris, France
- Correspondence: (A.K.); or (P.A.)
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Hubbard J, Kobayashi Frisk M, Ruppert E, Tsai JW, Fuchs F, Robin-Choteau L, Husse J, Calvel L, Eichele G, Franken P, Bourgin P. Dissecting and modeling photic and melanopsin effects to predict sleep disturbances induced by irregular light exposure in mice. Proc Natl Acad Sci U S A 2021; 118:e2017364118. [PMID: 34155139 PMCID: PMC8237663 DOI: 10.1073/pnas.2017364118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Artificial lighting, day-length changes, shift work, and transmeridian travel all lead to sleep-wake disturbances. The nychthemeral sleep-wake cycle (SWc) is known to be controlled by output from the central circadian clock in the suprachiasmatic nuclei (SCN), which is entrained to the light-dark cycle. Additionally, via intrinsically photosensitive retinal ganglion cells containing the photopigment melanopsin (Opn4), short-term light-dark alternations exert direct and acute influences on sleep and waking. However, the extent to which longer exposures typically experienced across the 24-h day exert such an effect has never been clarified or quantified, as disentangling sustained direct light effects (SDLE) from circadian effects is difficult. Recording sleep in mice lacking a circadian pacemaker, either through transgenesis (Syt10cre/creBmal1fl/- ) or SCN lesioning and/or melanopsin-based phototransduction (Opn4-/- ), we uncovered, contrary to prevailing assumptions, that the contribution of SDLE is as important as circadian-driven input in determining SWc amplitude. Specifically, SDLE were primarily mediated (>80%) through melanopsin, of which half were then relayed through the SCN, revealing an ancillary purpose for this structure, independent of its clock function in organizing SWc. Based on these findings, we designed a model to estimate the effect of atypical light-dark cycles on SWc. This model predicted SWc amplitude in mice exposed to simulated transequatorial or transmeridian paradigms. Taken together, we demonstrate this SDLE is a crucial mechanism influencing behavior on par with the circadian system. In a broader context, these findings mandate considering SDLE, in addition to circadian drive, for coping with health consequences of atypical light exposure in our society.
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Affiliation(s)
- Jeffrey Hubbard
- CNRS-Unité Propre de Recherche (UPR) 3212, Institute of Cellular and Integrative Neurosciences, 67084 Strasbourg, France
- International Research Center for ChronoSomnology, Translational Medicine Federation Strasbourg, Sleep Disorders Center, Strasbourg University Hospital, University of Strasbourg, 67000 Strasbourg, France
| | - Mio Kobayashi Frisk
- CNRS-Unité Propre de Recherche (UPR) 3212, Institute of Cellular and Integrative Neurosciences, 67084 Strasbourg, France
- International Research Center for ChronoSomnology, Translational Medicine Federation Strasbourg, Sleep Disorders Center, Strasbourg University Hospital, University of Strasbourg, 67000 Strasbourg, France
| | - Elisabeth Ruppert
- CNRS-Unité Propre de Recherche (UPR) 3212, Institute of Cellular and Integrative Neurosciences, 67084 Strasbourg, France
- International Research Center for ChronoSomnology, Translational Medicine Federation Strasbourg, Sleep Disorders Center, Strasbourg University Hospital, University of Strasbourg, 67000 Strasbourg, France
| | - Jessica W Tsai
- Department of Biology, Stanford University, Stanford, CA 94305
| | - Fanny Fuchs
- CNRS-Unité Propre de Recherche (UPR) 3212, Institute of Cellular and Integrative Neurosciences, 67084 Strasbourg, France
- International Research Center for ChronoSomnology, Translational Medicine Federation Strasbourg, Sleep Disorders Center, Strasbourg University Hospital, University of Strasbourg, 67000 Strasbourg, France
| | - Ludivine Robin-Choteau
- CNRS-Unité Propre de Recherche (UPR) 3212, Institute of Cellular and Integrative Neurosciences, 67084 Strasbourg, France
- European Center for Diabetes Studies, 67200 Strasbourg, France
| | - Jana Husse
- Department of Genes and Behavior, Max Planck Institute for Biophysical Chemistry, 37077 Goettingen, Germany
| | - Laurent Calvel
- CNRS-Unité Propre de Recherche (UPR) 3212, Institute of Cellular and Integrative Neurosciences, 67084 Strasbourg, France
- International Research Center for ChronoSomnology, Translational Medicine Federation Strasbourg, Sleep Disorders Center, Strasbourg University Hospital, University of Strasbourg, 67000 Strasbourg, France
| | - Gregor Eichele
- Department of Genes and Behavior, Max Planck Institute for Biophysical Chemistry, 37077 Goettingen, Germany
| | - Paul Franken
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland
| | - Patrice Bourgin
- CNRS-Unité Propre de Recherche (UPR) 3212, Institute of Cellular and Integrative Neurosciences, 67084 Strasbourg, France;
- International Research Center for ChronoSomnology, Translational Medicine Federation Strasbourg, Sleep Disorders Center, Strasbourg University Hospital, University of Strasbourg, 67000 Strasbourg, France
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13
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Hughes ATL, Samuels RE, Baño-Otálora B, Belle MDC, Wegner S, Guilding C, Northeast RC, Loudon ASI, Gigg J, Piggins HD. Timed daily exercise remodels circadian rhythms in mice. Commun Biol 2021; 4:761. [PMID: 34145388 PMCID: PMC8213798 DOI: 10.1038/s42003-021-02239-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 05/18/2021] [Indexed: 01/26/2023] Open
Abstract
Regular exercise is important for physical and mental health. An underexplored and intriguing property of exercise is its actions on the body’s 24 h or circadian rhythms. Molecular clock cells in the brain’s suprachiasmatic nuclei (SCN) use electrical and chemical signals to orchestrate their activity and convey time of day information to the rest of the brain and body. To date, the long-lasting effects of regular physical exercise on SCN clock cell coordination and communication remain unresolved. Utilizing mouse models in which SCN intercellular neuropeptide signaling is impaired as well as those with intact SCN neurochemical signaling, we examined how daily scheduled voluntary exercise (SVE) influenced behavioral rhythms and SCN molecular and neuronal activities. We show that in mice with disrupted neuropeptide signaling, SVE promotes SCN clock cell synchrony and robust 24 h rhythms in behavior. Interestingly, in both intact and neuropeptide signaling deficient animals, SVE reduces SCN neural activity and alters GABAergic signaling. These findings illustrate the potential utility of regular exercise as a long-lasting and effective non-invasive intervention in the elderly or mentally ill where circadian rhythms can be blunted and poorly aligned to the external world. Using mice with disrupted neuropeptide signaling, Hughes et al. show that daily scheduled voluntary exercise (SVE) promotes suprachiasmatic nuclei (SCN) clock cell synchrony and robust 24 h rhythms in behavior. This study suggests the potential utility of regular exercise as a non-invasive intervention for the elderly or mentally ill, where circadian rhythms can be poorly aligned to the external world.
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Affiliation(s)
- Alun Thomas Lloyd Hughes
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, UK
| | - Rayna Eve Samuels
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Beatriz Baño-Otálora
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Mino David Charles Belle
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,University of Exeter Medical School, Exeter, UK
| | - Sven Wegner
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Clare Guilding
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,School of Medical Education, Newcastle University, Newcastle, UK
| | | | | | - John Gigg
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Hugh David Piggins
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK. .,School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, UK.
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14
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Nesan D, Feighan KM, Antle MC, Kurrasch DM. Gestational low-dose BPA exposure impacts suprachiasmatic nucleus neurogenesis and circadian activity with transgenerational effects. SCIENCE ADVANCES 2021; 7:eabd1159. [PMID: 34049886 PMCID: PMC8163075 DOI: 10.1126/sciadv.abd1159] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 04/09/2021] [Indexed: 05/30/2023]
Abstract
Critical physiological processes such as sleep and stress that underscore health are regulated by an intimate interplay between the endocrine and nervous systems. Here, we asked how fetal exposure to the endocrine disruptor found in common plastics, bisphenol A (BPA), causes lasting effects on adult animal behaviors. Adult mice exposed to low-dose BPA during gestation displayed notable disruption in circadian activity, social interactions, and associated neural hyperactivity, with some phenotypes maintained transgenerationally. Gestational BPA exposure increased vasopressin+ neurons in the suprachiasmatic nucleus (SCN), the region that regulates circadian rhythms, of F1 and F3 generations. Mechanistically, BPA increased proliferation of hypothalamic neural progenitors ex vivo and caused precocious neurogenesis in vivo. Co-antagonism of both estrogen and androgen receptors was necessary to block BPA's effects on hypothalamic neural progenitors, illustrating a dual role for these endocrine targets. Together, gestational BPA exposure affects development of circadian centers, with lasting consequences across generations.
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Affiliation(s)
- Dinushan Nesan
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Kira M Feighan
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Michael C Antle
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Department of Psychology, Faculty of Arts, University of Calgary, Calgary, AB, Canada
- Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Deborah M Kurrasch
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
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15
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Jones AA, Nelson LR, Marino GM, Chappelle NA, Joye DAM, Arble DM. Photoperiod Manipulation Reveals a Light-Driven Component to Daily Patterns of Ventilation in Male C57Bl/6J Mice. J Biol Rhythms 2021; 36:346-358. [PMID: 33685258 DOI: 10.1177/0748730421992581] [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: 11/17/2022]
Abstract
Obstructive sleep apnea is a common sleep disorder that increases risk for cardiovascular disease and mortality. The severity of sleep-disordered breathing in obstructive sleep apnea patients fluctuates with the seasons, opening the possibility that seasonal changes in light duration, or photoperiod, can influence mechanisms of breathing. Photoperiod can have profound effects on internal timekeeping and can reshape metabolic rhythms in mammals. While the daily rhythm in ventilation is largely shaped by the metabolic rate, less is known about whether ventilatory rhythms are altered in accordance with metabolism under different photoperiods. Here, we investigate the relationship between ventilation and metabolism under different photoperiods using whole-body plethysmography and indirect calorimetry. We find that the daily timing of ventilation is chiefly synchronized to dark onset and that light cues are important for maintaining daily ventilatory rhythms. Moreover, changes in ventilatory patterns are not paralleled by changes in oxygen consumption, energy expenditure, or respiratory exchange rate under different photoperiods. We conclude that ventilatory patterns are not only shaped by the metabolic rate and circadian timing but are also influenced by other light-driven factors. Collectively, these findings have clinical implications for the seasonal variations in sleep-disordered breathing found in individuals with obstructive sleep apnea.
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Affiliation(s)
- Aaron A Jones
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
| | - Lauren R Nelson
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
| | - Gabriella M Marino
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
| | - Nakia A Chappelle
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
| | - Deborah A M Joye
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin
| | - Deanna M Arble
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
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16
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Finger A, Kramer A. Mammalian circadian systems: Organization and modern life challenges. Acta Physiol (Oxf) 2021; 231:e13548. [PMID: 32846050 DOI: 10.1111/apha.13548] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/04/2020] [Accepted: 08/11/2020] [Indexed: 12/11/2022]
Abstract
Humans and other mammalian species possess an endogenous circadian clock system that has evolved in adaptation to periodically reoccurring environmental changes and drives rhythmic biological functions, as well as behavioural outputs with an approximately 24-hour period. In mammals, body clocks are hierarchically organized, encompassing a so-called pacemaker clock in the hypothalamic suprachiasmatic nucleus (SCN), non-SCN brain and peripheral clocks, as well as cell-autonomous oscillators within virtually every cell type. A functional clock machinery on the molecular level, alignment among body clocks, as well as synchronization between endogenous circadian and exogenous environmental cycles has been shown to be crucial for our health and well-being. Yet, modern life constantly poses widespread challenges to our internal clocks, for example artificial lighting, shift work and trans-meridian travel, potentially leading to circadian disruption or misalignment and the emergence of associated diseases. For instance many of us experience a mismatch between sleep timing on work and free days (social jetlag) in our everyday lives without being aware of health consequences that may arise from such chronic circadian misalignment, Hence, this review provides an overview of the organization and molecular built-up of the mammalian circadian system, its interactions with the outside world, as well as pathologies arising from circadian disruption and misalignment.
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Affiliation(s)
- Anna‐Marie Finger
- Laboratory of Chronobiology Institute for Medical immunology Charité Universitätsmedizin Berlin Berlin Germany
- Berlin Institute of Health (BIH) Berlin Germany
| | - Achim Kramer
- Laboratory of Chronobiology Institute for Medical immunology Charité Universitätsmedizin Berlin Berlin Germany
- Berlin Institute of Health (BIH) Berlin Germany
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17
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Díaz NM, Lang RA, Van Gelder RN, Buhr ED. Wounding Induces Facultative Opn5-Dependent Circadian Photoreception in the Murine Cornea. Invest Ophthalmol Vis Sci 2021; 61:37. [PMID: 32543667 PMCID: PMC7415322 DOI: 10.1167/iovs.61.6.37] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Autonomous molecular circadian clocks are present in the majority of mammalian tissues. These clocks are synchronized to phases appropriate for their physiologic role by internal systemic cues, external environmental cues, or both. The circadian clocks of the in vivo mouse cornea synchronize to the phase of the brain's master clock primarily through systemic cues, but ex vivo corneal clocks entrain to environmental light cycles. We evaluated the underlying mechanisms of this difference. Methods Molecular circadian clocks of mouse corneas were evaluated in vivo and ex vivo for response to environmental light. The presence of opsins and effect of genetic deletion of opsins were evaluated for influence on circadian photoresponses. Opn5-expressing cells were identified using Opn5Cre;Ai14 mice and RT-PCR, and they were characterized using immunocytochemistry. Results Molecular circadian clocks of the cornea remain in phase with behavioral circadian locomotor rhythms in vivo but are photoentrainable in tissue culture. After full-thickness incision or epithelial debridement, expression of the opsin photopigment Opn5 is induced in the cornea in a subset of preexisting epithelial cells adjacent to the wound site. This induction coincides with conferral of direct, short-wavelength light sensitivity to the circadian clocks throughout the cornea. Conclusions Corneal circadian rhythms become photosensitive after wounding. Opn5 gene function (but not Opn3 or Opn4 function) is necessary for induced photosensitivity. These results demonstrate that opsin-dependent direct light sensitivity can be facultatively induced in the murine cornea.
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18
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Sokolowska E, Viitanen R, Misiewicz Z, Mennesson M, Saarnio S, Kulesskaya N, Kängsep S, Liljenbäck H, Marjamäki P, Autio A, Callan SA, Nuutila P, Roivainen A, Partonen T, Hovatta I. The circadian gene Cryptochrome 2 influences stress-induced brain activity and depressive-like behavior in mice. GENES BRAIN AND BEHAVIOR 2020; 20:e12708. [PMID: 33070440 DOI: 10.1111/gbb.12708] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 09/15/2020] [Accepted: 10/14/2020] [Indexed: 12/16/2022]
Abstract
Cryptochrome 2 (Cry2) is a core clock gene important for circadian regulation. It has also been associated with anxiety and depressive-like behaviors in mice, but the previous findings have been conflicting in terms of the direction of the effect. To begin to elucidate the molecular mechanisms of this association, we carried out behavioral testing, PET imaging, and gene expression analysis of Cry2-/- and Cry2+/+ mice. Compared to Cry2+/+ mice, we found that Cry2-/- mice spent less time immobile in the forced swim test, suggesting reduced despair-like behavior. Moreover, Cry2-/- mice had lower saccharin preference, indicative of increased anhedonia. In contrast, we observed no group differences in anxiety-like behavior. The behavioral changes were accompanied by lower metabolic activity of the ventro-medial hypothalamus, suprachiasmatic nuclei, ventral tegmental area, anterior and medial striatum, substantia nigra, and habenula after cold stress as measured by PET imaging with a glucose analog. Although the expression of many depression-associated and metabolic genes was upregulated or downregulated by cold stress, we observed no differences between Cry2-/- and Cry2+/+ mice. These findings are consistent with other studies showing that Cry2 is required for normal emotional behavior. Our findings confirm previous roles of Cry2 in behavior and extend them by showing that the effects on behavior may be mediated by changes in brain metabolism.
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Affiliation(s)
- Ewa Sokolowska
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki, Finland
| | | | - Zuzanna Misiewicz
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki, Finland.,Department of Psychology and Logopedics, University of Helsinki, Helsinki, Finland
| | - Marie Mennesson
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki, Finland.,Department of Psychology and Logopedics, University of Helsinki, Helsinki, Finland.,SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Suvi Saarnio
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki, Finland
| | - Natalia Kulesskaya
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki, Finland
| | - Sanna Kängsep
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki, Finland
| | - Heidi Liljenbäck
- Turku PET Centre, University of Turku, Turku, Finland.,Turku Center for Disease Modeling, University of Turku, Turku, Finland
| | | | - Anu Autio
- Turku PET Centre, University of Turku, Turku, Finland
| | - Saija-Anita Callan
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki, Finland
| | - Pirjo Nuutila
- Turku PET Centre, University of Turku, Turku, Finland.,Department of Endocrinology, Turku University Hospital, Turku, Finland.,Turku PET Centre, Turku University Hospital, Turku, Finland
| | - Anne Roivainen
- Turku PET Centre, University of Turku, Turku, Finland.,Turku Center for Disease Modeling, University of Turku, Turku, Finland.,Turku PET Centre, Turku University Hospital, Turku, Finland
| | - Timo Partonen
- Department of Public Health Solutions, National Institute for Health and Welfare, Helsinki, Finland
| | - Iiris Hovatta
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki, Finland.,Department of Psychology and Logopedics, University of Helsinki, Helsinki, Finland.,SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Department of Public Health Solutions, National Institute for Health and Welfare, Helsinki, Finland.,Neuroscience Center, Helsinki Institute of Life Science HiLIFE, University of Helsinki, Helsinki, Finland
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19
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Luo PH, Shu YM, Ni RJ, Liu YJ, Zhou JN. A Characteristic Expression Pattern of Core Circadian Genes in the Diurnal Tree Shrew. Neuroscience 2020; 437:145-160. [PMID: 32339628 DOI: 10.1016/j.neuroscience.2020.04.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 04/16/2020] [Accepted: 04/17/2020] [Indexed: 02/08/2023]
Abstract
The day-active tree shrew may serve as an animal model of human-like diurnal rhythms. However, the molecular basis for circadian rhythms in this species has remained unclear. In the present study, we investigated the expression patterns of core circadian genes involved in transcriptional/translational feedback loops (TTFLs) in both central and peripheral tissues of the tree shrew. The expression of 12 core circadian genes exhibited similar rhythmic patterns in the olfactory bulb, prefrontal cortex, hippocampus, and cerebellum, while the hypothalamus exhibited the weakest oscillations. The rhythms in peripheral tissues, especially the liver, were much more robust than those in brain tissues. ARNTL and NPAS2 were weakly rhythmic in brain tissues but exhibited almost the strongest rhythmicity in peripheral tissues. CLOCK and CRY2 exhibited the weakest rhythms in both central and peripheral tissues, while NR1D1 and CIART exhibited robust rhythms in both tissues. Most of these circadian genes were highly expressed at light/dark transitions in both brain and peripheral tissues, such as ARNTL and NPAS2 peaking at dusk while PERs peaking at dawn. Additionally, the peripheral clock was phase-advanced relative to the brain clock, as there was a significant advance (2-4 h) for PER3, DBP, NR1D1 and NR1D2. Furthermore, these genes exhibited an anti-phasic relationship between the diurnal tree shrew and the nocturnal mouse (i.e., 12-h phasing differential). Collectively, our findings demonstrate a characteristic expression pattern of core circadian genes in the tree shrew, which may provide a means for elucidating molecular mechanisms of diurnal rhythms.
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Affiliation(s)
- Peng-Hao Luo
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Yu-Mian Shu
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei, China; School of Architecture and Civil Engineering, Chengdu University, Chengdu, China
| | - Rong-Jun Ni
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei, China; Psychiatric Laboratory and Mental Health Center, West China Hospital of Sichuan University, Chengdu, China
| | - Ya-Jing Liu
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei, China; Department of Obstetrics and Gynecology, Center for Reproductive Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Jiang-Ning Zhou
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei, China.
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20
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Onishi KG, Maneval AC, Cable EC, Tuohy MC, Scasny AJ, Sterina E, Love JA, Riggle JP, Malamut LK, Mukerji A, Novo JS, Appah-Sampong A, Gary JB, Prendergast BJ. Circadian and circannual timescales interact to generate seasonal changes in immune function. Brain Behav Immun 2020; 83:33-43. [PMID: 31351184 DOI: 10.1016/j.bbi.2019.07.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 07/14/2019] [Accepted: 07/23/2019] [Indexed: 12/22/2022] Open
Abstract
Annual changes in day length enhance or suppress diverse aspects of immune function, giving rise to seasonal cycles of illness and mortality. The daily light-dark cycle also entrains circadian rhythms in immunity. Most published reports on immunological seasonality rely on measurements or interventions performed only at one point in the day. Because there can be no perfect matching of circadian phase across photoperiods of different duration, the manner in which these timescales interact to affect immunity is not understood. We examined whether photoperiodic changes in immune function reflect phenotypic changes that persist throughout the daily cycle, or merely reflect photoperiodic shifts in the circadian phase alignment of immunological rhythms. Diurnal rhythms in blood leukocyte trafficking, infection induced sickness responses, and delayed-type hypersensitivity skin inflammatory responses were examined at high-frequency sampling intervals (every 3 h) in Siberian hamsters (Phodopus sungorus) following immunological adaptation to summer or winter photoperiods. Photoperiod profoundly enhanced or suppressed immune function, in a trait-specific manner, and we were unable to identify a phase alignment of diurnal waveforms which eliminated these enhancing and suppressing effects of photoperiod. These results support the hypothesis that seasonal timescales affect immunity via mechanisms independent of circadian entrainment of the immunological circadian waveform.
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Affiliation(s)
- Kenneth G Onishi
- Department of Psychology and Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, United States.
| | - Andrew C Maneval
- Department of Psychology and Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, United States
| | - Erin C Cable
- Department of Psychology and Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, United States
| | - Mary Claire Tuohy
- Department of Psychology and Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, United States
| | - Andrew J Scasny
- Department of Psychology and Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, United States
| | - Evelina Sterina
- Department of Psychology and Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, United States
| | - Jharnae A Love
- Department of Psychology and Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, United States
| | - Jonathan P Riggle
- Department of Psychology and Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, United States
| | - Leah K Malamut
- Department of Psychology and Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, United States
| | - Aashna Mukerji
- Department of Psychology and Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, United States
| | - Jennifer S Novo
- Department of Psychology and Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, United States
| | - Abena Appah-Sampong
- Department of Psychology and Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, United States
| | - Joseph B Gary
- Department of Psychology and Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, United States
| | - Brian J Prendergast
- Department of Psychology and Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, United States; Committee on Neurobiology, University of Chicago, Chicago, IL 60637, United States; Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, University of Chicago, Chicago, IL 60637, United States
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21
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Manoogian ENC, Kumar A, Obed D, Bergan J, Bittman EL. Suprachiasmatic function in a circadian period mutant: Duper alters light-induced activation of vasoactive intestinal peptide cells and PERIOD1 immunostaining. Eur J Neurosci 2019; 48:3319-3334. [PMID: 30346078 DOI: 10.1111/ejn.14214] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 09/07/2018] [Accepted: 09/18/2018] [Indexed: 11/28/2022]
Abstract
Mammalian circadian rhythms are entrained by photic stimuli that are relayed by retinal projections to the core of the suprachiasmatic nucleus (SCN). Neuronal activation, as demonstrated by expression of the immediate early gene c-fos, leads to transcription of the core clock gene per1. The duper mutation in hamsters shortens circadian period and amplifies light-induced phase shifts. We performed two experiments to compare the number of c-FOS immunoreactive (ir) and PER1-ir cells, and the intensity of staining, in the SCN of wild-type (WT) and duper hamsters at various intervals after presentation of a 15-min light pulse in the early subjective night. Light-induced c-FOS-ir within 1 hr in the dorsocaudal SCN of duper, but not WT hamsters. In cells that express vasoactive intestinal peptide (VIP), which plays a critical role in synchronization of SCN cellular oscillators, light-induced c-FOS-ir was greater in duper than WT hamsters. After the light pulse, PER1-ir cells were found in more medial portions of the SCN than FOS-ir, and appeared with a longer latency and over a longer time course, in VIP cells of duper than wild-type hamsters. Our results indicate that the duper allele alters SCN function in ways that may contribute to changes in free running period and phase resetting.
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Affiliation(s)
- Emily N C Manoogian
- Program in Neuroscience and Behavior, University of Massachusetts, Amherst, Massachusetts
| | - Ajay Kumar
- Program in Neuroscience and Behavior, University of Massachusetts, Amherst, Massachusetts
| | - Doha Obed
- Department of Biology, University of Massachusetts, Amherst, Massachusetts
| | - Joseph Bergan
- Psychological and Brain Sciences and Program in Neuroscience and Behavior, University of Massachusetts, Amherst, Massachusetts
| | - Eric L Bittman
- Department of Biology, Program in Neuroscience and Behavior, University of Massachusetts, Amherst, Massachusetts
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22
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Rohr KE, Pancholi H, Haider S, Karow C, Modert D, Raddatz NJ, Evans J. Seasonal plasticity in GABA A signaling is necessary for restoring phase synchrony in the master circadian clock network. eLife 2019; 8:49578. [PMID: 31746738 PMCID: PMC6867713 DOI: 10.7554/elife.49578] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Accepted: 10/15/2019] [Indexed: 12/14/2022] Open
Abstract
Annual changes in the environment threaten survival, and numerous biological processes in mammals adjust to this challenge via seasonal encoding by the suprachiasmatic nucleus (SCN). To tune behavior according to day length, SCN neurons display unified rhythms with synchronous phasing when days are short, but will divide into two sub-clusters when days are long. The transition between SCN states is critical for maintaining behavioral responses to seasonal change, but the mechanisms regulating this form of neuroplasticity remain unclear. Here we identify that a switch in chloride transport and GABAA signaling is critical for maintaining state plasticity in the SCN network. Further, we reveal that blocking excitatory GABAA signaling locks the SCN into its long day state. Collectively, these data demonstrate that plasticity in GABAA signaling dictates how clock neurons interact to maintain environmental encoding. Further, this work highlights factors that may influence susceptibility to seasonal disorders in humans. In winter, as the days become shorter, millions of people find that their mood and energy levels start to drop. They crave carbohydrates, struggle with their weight, and find it harder to get out of bed in the mornings. These individuals are suffering from the ‘winter blues’ or seasonal affective disorder (SAD), and most find that their symptoms spontaneously improve in the spring when the days become longer again. Many also benefit from bright light therapy during the winter months, but not everyone responds fully to this treatment, so additional options are needed. The winter blues occur when the brain adjusts to changes in day length with the onset of winter. The brain region responsible for making this adjustment is the suprachiasmatic nucleus (SCN). The SCN is the master clock of the brain that coordinates the body’s circadian rhythms – the daily fluctuations in things like appetite, body temperature, sleep and wakefulness. But as well as being the brain’s clock, the SCN is also the brain’s calendar. In winter, when the days are short, SCN neurons coordinate their activity and fire in synchrony. But in summer, when the days are long, SCN neurons divide into two clusters, which fire at different times. By transitioning between these two states, the SCN helps the body adjust to seasonal changes in day length. Rohr, Pancholi et al. now provide new insight into the mechanism behind this process by showing that light alters the neurochemistry of the SCN. Exposing mice to long days causes a brain chemical called GABA to switch from inhibiting neurons in the SCN to activating them. Blocking this switch from inhibition to activation locks the SCN into its 'summer state'. Rohr, Pancholi et al. propose that this failure to transition to the winter state may be an interesting way to prevent the winter blues. While much remains to be learned about this process, these findings pave the way for better understanding the neurobiology of winter depression and how best to treat it.
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Affiliation(s)
- Kayla E Rohr
- Department of Biomedical Sciences, Marquette University, Milwaukee, United States
| | - Harshida Pancholi
- Department of Biomedical Sciences, Marquette University, Milwaukee, United States
| | - Shabi Haider
- Department of Biomedical Sciences, Marquette University, Milwaukee, United States
| | - Christopher Karow
- Department of Biomedical Sciences, Marquette University, Milwaukee, United States
| | - David Modert
- Department of Biomedical Sciences, Marquette University, Milwaukee, United States
| | - Nicholas J Raddatz
- Department of Biomedical Sciences, Marquette University, Milwaukee, United States
| | - Jennifer Evans
- Department of Biomedical Sciences, Marquette University, Milwaukee, United States
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23
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Bittman EL. Circadian Function in Multiple Cell Types Is Necessary for Proper Timing of the Preovulatory LH Surge. J Biol Rhythms 2019; 34:622-633. [PMID: 31530063 DOI: 10.1177/0748730419873511] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The timing of the preovulatory surge of luteinizing hormone (LH), which occurs on the evening of proestrus in female mice, is determined by the circadian system. The identity of cells that control the phase of the LH surge is unclear: evidence supports a role of arginine vasopressin (AVP) cells of the suprachiasmatic nucleus (SCN), but it is not known whether vasopressinergic neurons are necessary or sufficient to account for circadian control of ovulation. Among other cell types, evidence also suggests important roles of circadian function of kisspeptin cells of the anteroventral periventricular nucleus (AvPV) and gonadotropin-releasing hormone (GnRH) neurons of the preoptic area (POA), whose discharge is immediately responsible for the discharge of LH from the anterior pituitary. The present studies used an ovariectomized, estradiol-treated preparation to determine critical cell types whose clock function is critical to the timing of LH secretion. As expected, the LH surge occurred at or shortly after ZT12 in control mice. In further confirmation of circadian control, the surge was advanced by 2 h in tau mutant animals. The timing of the surge was altered to varying degrees by conditional deletion of Bmal1 in AVPCre, KissCreBAC, and GnRHCreBAC mice. Excision of the mutant Cnsk1e (tau) allele in AVP neurons resulted in a reversion of the surge to the ZT12. Conditional deletion of Bmal1 in Kiss1 or GnRH neurons had no noticeable effect on locomotor rhythms, but targeting of AVP neurons produced variable effects on circadian period that did not always correspond to changes in the phase of LH secretion. The results indicate that circadian function in multiple cell types is necessary for proper timing of the LH surge.
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Affiliation(s)
- Eric L Bittman
- Department of Biology and Program in Neuroscience and Behavior, University of Massachusetts, Amherst, Massachusetts
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24
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Fernandez F. Circadian Responses to Fragmented Light: Research Synopsis in Humans. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2019; 92:337-348. [PMID: 31249494 PMCID: PMC6585514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
Light is the chief signal used by the human circadian pacemaker to maintain precise biological timekeeping. Though it has been historically assumed that light resets the pacemaker's rhythm in a dose-dependent fashion, a number of studies report enhanced circadian photosensitivity to the initial moments of light exposure, such that there are quickly diminishing returns on phase-shifting the longer the light is shown. In the current review, we summarize findings from a family of experiments conducted over two decades in the research wing of the Brigham and Women's Hospital that examined the human pacemaker's responses to standardized changes in light patterns generated from an overhead fluorescent ballast. Across several hundred days of laboratory recording, the research group observed phase-shifts in the body temperature and melatonin rhythms that scaled with illuminance. However, as suspected, phase resetting was optimized when exposure occurred as a series of minute-long episodes separated by periods of intervening darkness. These observations set the stage for a more recent program of study at Stanford University that evaluated whether the human pacemaker was capable of integrating fragmented bursts of light in much the same way it perceived steady luminance. The results here suggest that ultra-short durations of light-lasting just 1-2 seconds in total-can elicit pacemaker responses rivaling those created by continuous hour-long stimulation if those few seconds of light are evenly distributed across the hour as discreet 2-millisecond pulses. We conclude our review with a brief discussion of these findings and their potential application in future phototherapy techniques.
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Affiliation(s)
- Fabian Fernandez
- To whom all correspondence should be addressed: Fabian Fernandez, PhD, Department of Psychology, 1501 N. Campbell Avenue Life Sciences North, Room 349, Tucson, Arizona, 85724;
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25
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Felder-Schmittbuhl MP, Buhr ED, Dkhissi-Benyahya O, Hicks D, Peirson SN, Ribelayga CP, Sandu C, Spessert R, Tosini G. Ocular Clocks: Adapting Mechanisms for Eye Functions and Health. Invest Ophthalmol Vis Sci 2019; 59:4856-4870. [PMID: 30347082 PMCID: PMC6181243 DOI: 10.1167/iovs.18-24957] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Vision is a highly rhythmic function adapted to the extensive changes in light intensity occurring over the 24-hour day. This adaptation relies on rhythms in cellular and molecular processes, which are orchestrated by a network of circadian clocks located within the retina and in the eye, synchronized to the day/night cycle and which, together, fine-tune detection and processing of light information over the 24-hour period and ensure retinal homeostasis. Systematic or high throughput studies revealed a series of genes rhythmically expressed in the retina, pointing at specific functions or pathways under circadian control. Conversely, knockout studies demonstrated that the circadian clock regulates retinal processing of light information. In addition, recent data revealed that it also plays a role in development as well as in aging of the retina. Regarding synchronization by the light/dark cycle, the retina displays the unique property of bringing together light sensitivity, clock machinery, and a wide range of rhythmic outputs. Melatonin and dopamine play a particular role in this system, being both outputs and inputs for clocks. The retinal cellular complexity suggests that mechanisms of regulation by light are diverse and intricate. In the context of the whole eye, the retina looks like a major determinant of phase resetting for other tissues such as the retinal pigmented epithelium or cornea. Understanding the pathways linking the cell-specific molecular machineries to their cognate outputs will be one of the major challenges for the future.
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Affiliation(s)
- Marie-Paule Felder-Schmittbuhl
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Strasbourg, France
| | - Ethan D Buhr
- Department of Ophthalmology, University of Washington Medical School, Seattle, Washington, United States
| | - Ouria Dkhissi-Benyahya
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France
| | - David Hicks
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Strasbourg, France
| | - Stuart N Peirson
- Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Christophe P Ribelayga
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, United States
| | - Cristina Sandu
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Strasbourg, France
| | - Rainer Spessert
- Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Gianluca Tosini
- Neuroscience Institute and Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States
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26
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Abstract
Disruption of circadian clocks is strongly associated with mood disorders. Chronotherapies targeting circadian rhythms have been shown to be very effective treatments of mood disorders, but still are not widely used in clinical practice. The mechanisms by which circadian disruption leads to mood disorders are poorly characterized and, therefore, may not convince clinicians to apply chronotherapies. Hence, in this review, we describe specific potential mechanisms, in order to make this connection more credible to clinicians. We believe that four major features of disrupted clocks may contribute to the development of mood disorders: (1) loss of synchronization to environmental 24-h rhythms, (2) internal desynchronization among body clocks, (3) low rhythm amplitude, and (4) changes in sleep architecture. Discussing these attributes and giving plausible examples, we will discuss prospects for relatively simple chronotherapies addressing these features that are easy to implement in clinical practice. Key messages In this review, we describe specific potential mechanisms by which disrupted clocks may contribute to the development of mood disorders: (1) loss of synchronization to environmental 24-h rhythms, (2) internal desynchronization among body clocks, (3) low rhythm amplitude, and (4) changes in sleep architecture. We provide prospects for relatively simple chronotherapies addressing these features that are easy to implement in clinical practice.
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Affiliation(s)
- Anisja Hühne
- a Circadian Biology Group, Department of Psychiatry , Ludwig Maximilian University , Munich , Germany
| | - David K Welsh
- b Veterans Affairs San Diego Healthcare System , San Diego , CA , USA.,c Department of Psychiatry & Center for Circadian Biology , University of California San Diego , La Jolla , CA , USA
| | - Dominic Landgraf
- a Circadian Biology Group, Department of Psychiatry , Ludwig Maximilian University , Munich , Germany
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27
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Leise TL, Goldberg A, Michael J, Montoya G, Solow S, Molyneux P, Vetrivelan R, Harrington ME. Recurring circadian disruption alters circadian clock sensitivity to resetting. Eur J Neurosci 2018; 51:2343-2354. [PMID: 30269396 DOI: 10.1111/ejn.14179] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 09/06/2018] [Accepted: 09/17/2018] [Indexed: 01/12/2023]
Abstract
A single phase advance of the light:dark (LD) cycle can temporarily disrupt synchrony of neural circadian rhythms within the suprachiasmatic nucleus (SCN) and between the SCN and peripheral tissues. Compounding this, modern life can involve repeated disruptive light conditions. To model chronic disruption to the circadian system, we exposed male mice to more than a month of a 20-hr light cycle (LD10:10), which mice typically cannot entrain to. Control animals were housed under LD12:12. We measured locomotor activity and body temperature rhythms in vivo, and rhythms of PER2::LUC bioluminescence in SCN and peripheral tissues ex vivo. Unexpectedly, we discovered strong effects of the time of dissection on circadian phase of PER2::LUC bioluminescent rhythms, which varied across tissues. White adipose tissue was strongly reset by dissection, while thymus phase appeared independent of dissection timing. Prior light exposure impacted the SCN, resulting in strong resetting of SCN phase by dissection for mice housed under LD10:10, and weak phase shifts by time of dissection in SCN from control LD12:12 mice. These findings suggest that exposure to circadian disruption may desynchronize SCN neurons, increasing network sensitivity to perturbations. We propose that tissues with a weakened circadian network, such as the SCN under disruptive light conditions, or with little to no coupling, for example, some peripheral tissues, will show increased resetting effects. In particular, exposure to light at inconsistent circadian times on a recurring weekly basis disrupts circadian rhythms and alters sensitivity of the SCN neural pacemaker to dissection time.
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Affiliation(s)
- Tanya L Leise
- Department of Mathematics and Statistics, Amherst College, Amherst, Massachusetts
| | - Ariella Goldberg
- Department of Mathematics and Statistics, Amherst College, Amherst, Massachusetts
| | - John Michael
- Department of Mathematics and Statistics, Amherst College, Amherst, Massachusetts
| | - Grace Montoya
- Department of Mathematics and Statistics, Amherst College, Amherst, Massachusetts
| | - Sabrina Solow
- Department of Mathematics and Statistics, Amherst College, Amherst, Massachusetts
| | - Penny Molyneux
- Neuroscience Program, Smith College, Northampton, Massachusetts
| | - Ramalingam Vetrivelan
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts
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28
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Bedont JL, Rohr KE, Bathini A, Hattar S, Blackshaw S, Sehgal A, Evans JA. Asymmetric vasopressin signaling spatially organizes the master circadian clock. J Comp Neurol 2018; 526:2048-2067. [PMID: 29931690 DOI: 10.1002/cne.24478] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 05/07/2018] [Accepted: 03/12/2018] [Indexed: 01/04/2023]
Abstract
The suprachiasmatic nucleus (SCN) is the neural network that drives daily rhythms in behavior and physiology. The SCN encodes environmental changes through the phasing of cellular rhythms across its anteroposterior axis, but it remains unknown what signaling mechanisms regulate clock function along this axis. Here we demonstrate that arginine vasopressin (AVP) signaling organizes the SCN into distinct anteroposterior domains. Spatial mapping of SCN gene expression using in situ hybridization delineated anterior and posterior domains for AVP signaling components, including complementary patterns of V1a and V1b expression that suggest different roles for these two AVP receptors. Similarly, anteroposterior patterning of transcripts involved in Vasoactive Intestinal Polypeptide- and Prokineticin2 signaling was evident across the SCN. Using bioluminescence imaging, we then revealed that inhibiting V1A and V1B signaling alters period and phase differentially along the anteroposterior SCN. V1 antagonism lengthened period the most in the anterior SCN, whereas changes in phase were largest in the posterior SCN. Further, separately antagonizing V1A and V1B signaling modulated SCN function in a manner that mapped onto anteroposterior expression patterns. Lastly, V1 antagonism influenced SCN period and phase along the dorsoventral axis, complementing effects on the anteroposterior axis. Together, these results indicate that AVP signaling modulates SCN period and phase in a spatially specific manner, which is expected to influence how the master clock interacts with downstream tissues and responds to environmental changes. More generally, we reveal anteroposterior asymmetry in neuropeptide signaling as a recurrent organizational motif that likely influences neural computations in the SCN clock network.
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Affiliation(s)
- Joseph L Bedont
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania.,Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21218
| | - Kayla E Rohr
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, 53233
| | - Abhijith Bathini
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21218
| | - Samer Hattar
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21218.,Department of Biology, Johns Hopkins University, Baltimore, MD, 21218
| | - Seth Blackshaw
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21218.,Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21218.,Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, 21218.,Center for Human Systems Biology, Johns Hopkins University School of Medicine, Baltimore, MD, 21218.,Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21218
| | - Amita Sehgal
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania
| | - Jennifer A Evans
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, 53233
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29
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Wacker D, Ludwig M. The role of vasopressin in olfactory and visual processing. Cell Tissue Res 2018; 375:201-215. [PMID: 29951699 PMCID: PMC6335376 DOI: 10.1007/s00441-018-2867-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Accepted: 05/31/2018] [Indexed: 12/23/2022]
Abstract
Neural vasopressin is a potent modulator of behaviour in vertebrates. It acts at both sensory processing regions and within larger regulatory networks to mediate changes in social recognition, affiliation, aggression, communication and other social behaviours. There are multiple populations of vasopressin neurons within the brain, including groups in olfactory and visual processing regions. Some of these vasopressin neurons, such as those in the main and accessory olfactory bulbs, anterior olfactory nucleus, piriform cortex and retina, were recently identified using an enhanced green fluorescent protein-vasopressin (eGFP-VP) transgenic rat. Based on the interconnectivity of vasopressin-producing and sensitive brain areas and in consideration of autocrine, paracrine and neurohormone-like actions associated with somato-dendritic release, we discuss how these different neuronal populations may interact to impact behaviour.
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Affiliation(s)
- Douglas Wacker
- School of STEM (Division of Biological Sciences), University of Washington Bothell, Bothell, WA, USA.
| | - Mike Ludwig
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK.,Centre for Neuroendocrinology, University of Pretoria, Pretoria, South Africa
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30
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A Meta-Analysis Characterizing Stem-Like Gene Expression in the Suprachiasmatic Nucleus and Its Circadian Clock. BIOMED RESEARCH INTERNATIONAL 2018; 2018:3610603. [PMID: 30046594 PMCID: PMC6038684 DOI: 10.1155/2018/3610603] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 04/24/2018] [Accepted: 05/28/2018] [Indexed: 12/17/2022]
Abstract
Cells expressing proteins characteristic of stem cells and progenitor cells are present in the suprachiasmatic nucleus (SCN) of the adult mammalian hypothalamus. Any relationship between this distinctive feature and the master circadian clock of the SCN is unclear. Considering the lack of obvious neurogenesis in the adult SCN relative to the hippocampus and other structures that provide neurons and glia, it is possible that the SCN has partially differentiated cells that can provide neural circuit plasticity rather than ongoing neurogenesis. To test this possibility, available databases and publications were explored to identify highly expressed genes in the mouse SCN that also have known or suspected roles in cell differentiation, maintenance of stem-like states, or cell-cell interactions found in adult and embryonic stem cells and cancer stem cells. The SCN was found to have numerous genes associated with stem cell maintenance and increased motility from which we selected 25 of the most relevant genes. Over ninety percent of these stem-like genes were expressed at higher levels in the SCN than in other brain areas. Further analysis of this gene set could provide a greater understanding of how adjustments in cell contacts alter period and phase relationships of circadian rhythms. Circadian timing and its role in cancer, sleep, and metabolic disorders are likely influenced by genes selected in this study.
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31
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Abstract
The eye contains a circadian system that acts independently from the master circadian clock located in the brain. This circadian system regulates important physiological functions within the eye. Emerging experimental evidence also indicates that disruption of the ocular circadian clock, or its outputs, negatively affects the overall health of the eye. Although previous studies have investigated the effect of aging on the regulation of circadian rhythms, no study has investigated the effects of aging on the circadian rhythm in the ocular system. The aim of the present study was to investigate how aging affects the circadian rhythm of PER2::LUC bioluminescence in the retina, retinal pigment epithelium (RPE), and cornea. Our data suggest that among the 3 different ocular tissues investigated, the retina appears to be the most affected by aging whereas the RPE and cornea are less affected by aging. Our data, along with studies of other organs and tissues, suggest that reduction in the amplitude of rhythms is probably the most severe effect of aging on the circadian clock.
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Affiliation(s)
| | - Gianluca Tosini
- Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, Georgia
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32
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Abstract
A new study utilizes transgenic mice to elucidate the coupling between cells of a neuronal pacemaker that determines circadian period.
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Affiliation(s)
- Eric L Bittman
- Department of Biology and Program in Neuroscience and Behavior, University of Massachusetts, Amherst, MA 01003, USA.
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33
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Abstract
Mammalian circadian clocks have a hierarchical organization, governed by the suprachiasmatic nucleus (SCN) in the hypothalamus. The brain itself contains multiple loci that maintain autonomous circadian rhythmicity, but the contribution of the non-SCN clocks to this hierarchy remains unclear. We examine circadian oscillations of clock gene expression in various brain loci and discovered that in mouse, robust, higher amplitude, relatively faster oscillations occur in the choroid plexus (CP) compared to the SCN. Our computational analysis and modeling show that the CP achieves these properties by synchronization of “twist” circadian oscillators via gap-junctional connections. Using an in vitro tissue coculture model and in vivo targeted deletion of the Bmal1 gene to silence the CP circadian clock, we demonstrate that the CP clock adjusts the SCN clock likely via circulation of cerebrospinal fluid, thus finely tuning behavioral circadian rhythms. The suprachiasmatic nucleus (SCN) has been thought of as the master circadian clock, but peripheral circadian clocks do exist. Here, the authors show that the choroid plexus displays oscillations more robust than the SCN and that can be described as a Poincaré oscillator with negative twist.
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34
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Photoperiod-Induced Neuroplasticity in the Circadian System. Neural Plast 2018; 2018:5147585. [PMID: 29681926 PMCID: PMC5851158 DOI: 10.1155/2018/5147585] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 01/11/2018] [Indexed: 01/01/2023] Open
Abstract
Seasonal changes in light exposure have profound effects on behavioral and physiological functions in many species, including effects on mood and cognitive function in humans. The mammalian brain's master circadian clock, the suprachiasmatic nucleus (SCN), transmits information about external light conditions to other brain regions, including some implicated in mood and cognition. Although the detailed mechanisms are not yet known, the SCN undergoes highly plastic changes at the cellular and network levels under different light conditions. We therefore propose that the SCN may be an essential mediator of the effects of seasonal changes of day length on mental health. In this review, we explore various forms of neuroplasticity that occur in the SCN and other brain regions to facilitate seasonal adaptation, particularly altered phase distribution of cellular circadian oscillators in the SCN and changes in hypothalamic neurotransmitter expression.
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35
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How does general anaesthesia affect the circadian clock? Sleep Med Rev 2018; 37:35-44. [DOI: 10.1016/j.smrv.2016.12.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 12/06/2016] [Accepted: 12/07/2016] [Indexed: 12/20/2022]
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36
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Abstract
Light improves cognitive function in humans; however, the neurobiological mechanisms underlying positive effects of light remain unclear. One obstacle is that most rodent models have employed lighting conditions that cause cognitive deficits rather than improvements. Here we have developed a mouse model where light improves cognitive function, which provides insight into mechanisms underlying positive effects of light. To increase light exposure without eliminating daily rhythms, we exposed mice to either a standard photoperiod or a long day photoperiod. Long days enhanced long-term recognition memory, and this effect was abolished by loss of the photopigment melanopsin. Further, long days markedly altered hippocampal clock function and elevated transcription of Insulin-like Growth Factor2 (Igf2). Up-regulation of Igf2 occurred in tandem with suppression of its transcriptional repressor Wilm’s tumor1. Consistent with molecular de-repression of Igf2, IGF2 expression was increased in the hippocampus before and after memory training. Lastly, long days occluded IGF2-induced improvements in recognition memory. Collectively, these results suggest that light changes hippocampal clock function to alter memory, highlighting novel mechanisms that may contribute to the positive effects of light. Furthermore, this study provides insight into how the circadian clock can regulate hippocampus-dependent learning by controlling molecular processes required for memory consolidation.
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37
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Ono D, Honma S, Nakajima Y, Kuroda S, Enoki R, Honma KI. Dissociation of Per1 and Bmal1 circadian rhythms in the suprachiasmatic nucleus in parallel with behavioral outputs. Proc Natl Acad Sci U S A 2017; 114:E3699-E3708. [PMID: 28416676 PMCID: PMC5422828 DOI: 10.1073/pnas.1613374114] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The temporal order of physiology and behavior in mammals is primarily regulated by the circadian pacemaker located in the hypothalamic suprachiasmatic nucleus (SCN). Taking advantage of bioluminescence reporters, we monitored the circadian rhythms of the expression of clock genes Per1 and Bmal1 in the SCN of freely moving mice and found that the rate of phase shifts induced by a single light pulse was different in the two rhythms. The Per1-luc rhythm was phase-delayed instantaneously by the light presented at the subjective evening in parallel with the activity onset of behavioral rhythm, whereas the Bmal1-ELuc rhythm was phase-delayed gradually, similar to the activity offset. The dissociation was confirmed in cultured SCN slices of mice carrying both Per1-luc and Bmal1-ELuc reporters. The two rhythms in a single SCN slice showed significantly different periods in a long-term (3 wk) culture and were internally desynchronized. Regional specificity in the SCN was not detected for the period of Per1-luc and Bmal1-ELuc rhythms. Furthermore, neither is synchronized with circadian intracellular Ca2+ rhythms monitored by a calcium indicator, GCaMP6s, or with firing rhythms monitored on a multielectrode array dish, although the coupling between the circadian firing and Ca2+ rhythms persisted during culture. These findings indicate that the expressions of two key clock genes, Per1 and Bmal1, in the SCN are regulated in such a way that they may adopt different phases and free-running periods relative to each other and are respectively associated with the expression of activity onset and offset.
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Affiliation(s)
- Daisuke Ono
- Photonic Bioimaging Section, Research Center for Cooperative Projects, Hokkaido University Graduate School of Medicine, Sapporo, 060-8638, Japan;
| | - Sato Honma
- Department of Chronomedicine, Hokkaido University Graduate School of Medicine, Sapporo, 060-8638, Japan;
| | - Yoshihiro Nakajima
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Takamatsu, Kagawa 761-0395, Japan
| | - Shigeru Kuroda
- Research Institute for Electronic Science, Hokkaido University, Sapporo, 001-0020, Japan
| | - Ryosuke Enoki
- Photonic Bioimaging Section, Research Center for Cooperative Projects, Hokkaido University Graduate School of Medicine, Sapporo, 060-8638, Japan
- Department of Chronomedicine, Hokkaido University Graduate School of Medicine, Sapporo, 060-8638, Japan
- Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Saitama 332-0012, Japan
| | - Ken-Ichi Honma
- Department of Chronomedicine, Hokkaido University Graduate School of Medicine, Sapporo, 060-8638, Japan
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38
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Chernysheva MP, Nozdrachev AD. Neuroendocrine hypothalamus as a homeostat of endogenous time. J EVOL BIOCHEM PHYS+ 2017. [DOI: 10.1134/s002209301701001x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Intrinsically Photosensitive Retinal Ganglion Cells (ipRGCs) Are Necessary for Light Entrainment of Peripheral Clocks. PLoS One 2016; 11:e0168651. [PMID: 27992553 PMCID: PMC5161485 DOI: 10.1371/journal.pone.0168651] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 12/04/2016] [Indexed: 11/23/2022] Open
Abstract
Light is a powerful entrainer of circadian clocks in almost all eukaryotic organisms promoting synchronization of internal circadian rhythms with external environmental light-dark (LD) cycles. In mammals, the circadian system is organized in a hierarchical manner, in which a central pacemaker in the suprachiasmatic nucleus (SCN) synchronizes oscillators in peripheral tissues. Recent evidence demonstrates that photoentrainment of the SCN proceeds via signaling from a subpopulation of retinal ganglion cells (RGCs) which are melanopsin-expressing and intrinsically photosensitive (ipRGCs). However, it is still unclear whether photoentrainment of peripheral clocks is mediated exclusively by the ipRGC system or if signaling from RGCs that do not express melanopsin also plays a role. Here we have used genetic “silencing” of ipRGC neurotransmission in mice to investigate whether this photoreceptive system is obligatory for the photoentrainment of peripheral circadian clocks. Genetic silencing of ipRGC neurotransmission in mice was achieved by expression of tetanus toxin light chain in melanopsin-expressing cells (Opn4::TeNT mouse line). Rhythms of the clock gene Period 2 in various peripheral tissues were measured by crossbreeding Opn4::TeNT mice with PER2 luciferase knock-in mice (mPER2Luc). We found that in Opn4::TeNT mice the pupillary light reflex, light modulation of activity, and circadian photoentrainment of locomotor activity were severely impaired. Furthermore, ex vivo cultures from Opn4::TeNT, mPER2Luc mice of the adrenal gland, cornea, lung, liver, pituitary and spleen exhibited robust circadian rhythms of PER2::LUC bioluminescence. However, their peak bioluminescence rhythms were not aligned to the projected LD cycles indicating their lack of photic entrainment in vivo. Finally, we found that the circadian rhythm in adrenal corticosterone in Opn4::TeNT mice, as monitored by in vivo subcutaneous microdialysis, was desynchronized from environmental LD cycles. Our findings reveal a non-redundant role of ipRGCs for photic entrainment of peripheral tissues, highlighting the importance of this photoreceptive system for the organismal adaptation to daily environmental LD cycles.
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Abstract
The mammalian circadian clock is a complex multi-scale, multivariable biological control system. In the past two decades, methods from systems engineering have led to numerous insights into the architecture and functionality of this system. In this review, we examine the mammalian circadian system through a process systems lens. We present a mathematical framework for examining the cellular circadian oscillator, and show recent extensions for understanding population-scale dynamics. We provide an overview of the routes by which the circadian system can be systemically manipulated, and present in silico proof of concept results for phase resetting of the clock via model predictive control.
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41
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Hughey JJ, Butte AJ. Differential Phasing between Circadian Clocks in the Brain and Peripheral Organs in Humans. J Biol Rhythms 2016; 31:588-597. [PMID: 27702781 PMCID: PMC5105327 DOI: 10.1177/0748730416668049] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The daily timing of mammalian physiology is coordinated by circadian clocks throughout the body. Although measurements of clock gene expression indicate that these clocks in mice are normally in phase with each other, the situation in humans remains unclear. We used publicly available data from five studies, comprising over 1000 samples, to compare the phasing of circadian gene expression in human brain and human blood. Surprisingly, after controlling for age, clock gene expression in brain was phase-delayed by ~8.5 h relative to that of blood. We then examined clock gene expression in two additional human organs and in organs from nine other mammalian species, as well as in the suprachiasmatic nucleus (SCN). In most tissues outside the SCN, the expression of clock gene orthologs showed a phase difference of ~12 h between diurnal and nocturnal species. The exception to this pattern was human brain, whose phasing resembled that of the SCN. Our results highlight the value of a multi-tissue, multi-species meta-analysis, and have implications for our understanding of the human circadian system.
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Affiliation(s)
- Jacob J Hughey
- Department of Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Atul J Butte
- Institute for Computational Health Sciences, University of California, San Francisco, California
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Kovanen L, Donner K, Kaunisto M, Partonen T. CRY1 and CRY2 genetic variants in seasonality: A longitudinal and cross-sectional study. Psychiatry Res 2016; 242:101-110. [PMID: 27267441 DOI: 10.1016/j.psychres.2016.05.044] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 05/27/2016] [Accepted: 05/30/2016] [Indexed: 12/15/2022]
Abstract
Cryptochromes are key components of the circadian clocks that generate and maintain seasonal variations. The aim of our study was to analyze the associations of CRY1 and CRY2 genetic variants with the problematicity of seasonal variations, and whether the problematicity of seasonal variations changed during the follow-up of 11 years. Altogether 21 CRY1 and 16 CRY2 single-nucleotide polymorphisms (SNPs) were genotyped and analyzed in 5910 individuals from a Finnish nationwide population-based sample who had filled in the self-report on the seasonal variations in mood and behavior in the year 2000. In the year 2011, 3356 of these individuals filled in the same self-report on the seasonal variations in mood and behavior. Regression models were used to test whether any of the SNPs associated with the problematicity of seasonal variations or with a change in the problematicity from 2000 to 2011. In the longitudinal analysis, CRY2 SNP rs61884508 was protective from worsening of problematicity of seasonal variations. In the cross-sectional analysis, CRY2 SNP rs72902437 showed evidence of association with problematicity of seasonal variations, as did SNP rs1554338 (in the MAPK8IP1 and downstream of CRY2).
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Affiliation(s)
- Leena Kovanen
- Department of Health, National Institute for Health and Welfare (THL), Helsinki, Finland.
| | - Kati Donner
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
| | - Mari Kaunisto
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland; Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland
| | - Timo Partonen
- Department of Health, National Institute for Health and Welfare (THL), Helsinki, Finland
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Evans JA. Collective timekeeping among cells of the master circadian clock. J Endocrinol 2016; 230:R27-49. [PMID: 27154335 PMCID: PMC4938744 DOI: 10.1530/joe-16-0054] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 05/06/2016] [Indexed: 01/09/2023]
Abstract
The suprachiasmatic nucleus (SCN) of the anterior hypothalamus is the master circadian clock that coordinates daily rhythms in behavior and physiology in mammals. Like other hypothalamic nuclei, the SCN displays an impressive array of distinct cell types characterized by differences in neurotransmitter and neuropeptide expression. Individual SCN neurons and glia are able to display self-sustained circadian rhythms in cellular function that are regulated at the molecular level by a 24h transcriptional-translational feedback loop. Remarkably, SCN cells are able to harmonize with one another to sustain coherent rhythms at the tissue level. Mechanisms of cellular communication in the SCN network are not completely understood, but recent progress has provided insight into the functional roles of several SCN signaling factors. This review discusses SCN organization, how intercellular communication is critical for maintaining network function, and the signaling mechanisms that play a role in this process. Despite recent progress, our understanding of SCN circuitry and coupling is far from complete. Further work is needed to map SCN circuitry fully and define the signaling mechanisms that allow for collective timekeeping in the SCN network.
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Affiliation(s)
- Jennifer A Evans
- Department of Biomedical SciencesMarquette University, Milwaukee, WI, USA
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44
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Abstract
In the mammalian suprachiasmatic nucleus (SCN), noisy cellular oscillators communicate within a neuronal network to generate precise system-wide circadian rhythms. Although the intracellular genetic oscillator and intercellular biochemical coupling mechanisms have been examined previously, the network topology driving synchronization of the SCN has not been elucidated. This network has been particularly challenging to probe, due to its oscillatory components and slow coupling timescale. In this work, we investigated the SCN network at a single-cell resolution through a chemically induced desynchronization. We then inferred functional connections in the SCN by applying the maximal information coefficient statistic to bioluminescence reporter data from individual neurons while they resynchronized their circadian cycling. Our results demonstrate that the functional network of circadian cells associated with resynchronization has small-world characteristics, with a node degree distribution that is exponential. We show that hubs of this small-world network are preferentially located in the central SCN, with sparsely connected shells surrounding these cores. Finally, we used two computational models of circadian neurons to validate our predictions of network structure.
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45
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Evans JA, Gorman MR. In synch but not in step: Circadian clock circuits regulating plasticity in daily rhythms. Neuroscience 2016; 320:259-80. [PMID: 26861419 DOI: 10.1016/j.neuroscience.2016.01.072] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 01/26/2016] [Accepted: 01/27/2016] [Indexed: 11/16/2022]
Abstract
The suprachiasmatic nucleus (SCN) is a network of neural oscillators that program daily rhythms in mammalian behavior and physiology. Over the last decade much has been learned about how SCN clock neurons coordinate together in time and space to form a cohesive population. Despite this insight, much remains unknown about how SCN neurons communicate with one another to produce emergent properties of the network. Here we review the current understanding of communication among SCN clock cells and highlight a collection of formal assays where changes in SCN interactions provide for plasticity in the waveform of circadian rhythms in behavior. Future studies that pair analytical behavioral assays with modern neuroscience techniques have the potential to provide deeper insight into SCN circuit mechanisms.
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Affiliation(s)
- J A Evans
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA.
| | - M R Gorman
- Department of Psychology, University of San Diego, La Jolla, CA, USA
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Webb AB, Oates AC. Timing by rhythms: Daily clocks and developmental rulers. Dev Growth Differ 2016; 58:43-58. [PMID: 26542934 PMCID: PMC4832293 DOI: 10.1111/dgd.12242] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 09/18/2015] [Accepted: 09/19/2015] [Indexed: 01/10/2023]
Abstract
Biological rhythms are widespread, allowing organisms to temporally organize their behavior and metabolism in advantageous ways. Such proper timing of molecular and cellular events is critical to their development and health. This is best understood in the case of the circadian clock that orchestrates the daily sleep/wake cycle of organisms. Temporal rhythms can also be used for spatial organization, if information from an oscillating system can be recorded within the tissue in a manner that leaves a permanent periodic pattern. One example of this is the "segmentation clock" used by the vertebrate embryo to rhythmically and sequentially subdivide its elongating body axis. The segmentation clock moves with the elongation of the embryo, such that its period sets the segment length as the tissue grows outward. Although the study of this system is still relatively young compared to the circadian clock, outlines of molecular, cellular, and tissue-level regulatory mechanisms of timing have emerged. The question remains, however, is it truly a clock? Here we seek to introduce the segmentation clock to a wider audience of chronobiologists, focusing on the role and control of timing in the system. We compare and contrast the segmentation clock with the circadian clock, and propose that the segmentation clock is actually an oscillatory ruler, with a primary function to measure embryonic space.
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Affiliation(s)
- Alexis B Webb
- The Francis Crick Institute, Mill Hill Laboratory, London, UK
| | - Andrew C Oates
- The Francis Crick Institute, Mill Hill Laboratory, London, UK
- University College London, Gower Street, London, UK
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