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Ono D, Weaver DR, Hastings MH, Honma KI, Honma S, Silver R. The Suprachiasmatic Nucleus at 50: Looking Back, Then Looking Forward. J Biol Rhythms 2024; 39:135-165. [PMID: 38366616 PMCID: PMC7615910 DOI: 10.1177/07487304231225706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2024]
Abstract
It has been 50 years since the suprachiasmatic nucleus (SCN) was first identified as the central circadian clock and 25 years since the last overview of developments in the field was published in the Journal of Biological Rhythms. Here, we explore new mechanisms and concepts that have emerged in the subsequent 25 years. Since 1997, methodological developments, such as luminescent and fluorescent reporter techniques, have revealed intricate relationships between cellular and network-level mechanisms. In particular, specific neuropeptides such as arginine vasopressin, vasoactive intestinal peptide, and gastrin-releasing peptide have been identified as key players in the synchronization of cellular circadian rhythms within the SCN. The discovery of multiple oscillators governing behavioral and physiological rhythms has significantly advanced our understanding of the circadian clock. The interaction between neurons and glial cells has been found to play a crucial role in regulating these circadian rhythms within the SCN. Furthermore, the properties of the SCN network vary across ontogenetic stages. The application of cell type-specific genetic manipulations has revealed components of the functional input-output system of the SCN and their correlation with physiological functions. This review concludes with the high-risk effort of identifying open questions and challenges that lie ahead.
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Affiliation(s)
- Daisuke Ono
- Stress Recognition and Response, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
- Department of Neural Regulation, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - David R Weaver
- Department of Neurobiology and NeuroNexus Institute, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Michael H Hastings
- Division of Neurobiology, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Ken-Ichi Honma
- Research and Education Center for Brain Science, Hokkaido University, Sapporo, Japan
- Center for Sleep and Circadian Rhythm Disorders, Sapporo Hanazono Hospital, Sapporo, Japan
| | - Sato Honma
- Research and Education Center for Brain Science, Hokkaido University, Sapporo, Japan
- Center for Sleep and Circadian Rhythm Disorders, Sapporo Hanazono Hospital, Sapporo, Japan
| | - Rae Silver
- Stress Recognition and Response, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
- Department of Neural Regulation, Nagoya University Graduate School of Medicine, Nagoya, Japan
- Department of Neuroscience & Behavior, Barnard College and Department of Psychology, Columbia University, New York City, New York, USA
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2
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Yaodong C, Zhang Y, Feng G, Lei Y, Liu Q, Liu Y. Light therapy for sleep disturbance comorbid depression in relation to neural circuits and interactive hormones-A systematic review. PLoS One 2023; 18:e0286569. [PMID: 37768984 PMCID: PMC10538739 DOI: 10.1371/journal.pone.0286569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 05/19/2023] [Indexed: 09/30/2023] Open
Abstract
AIM To provide an overview of the evidence on the effect of light therapy on sleep disturbance and depression, identify the light-active neural and hormonal correlates of the effect of light therapy on sleep disturbance comorbid depression (SDCD), and construct the mechanism by which light therapy alleviates SDCD. METHODS Articles published between 1981 and 2021 in English were accessed using Science Direct, Elsevier, and Google Scholar following a three-step searching process via evolved keywords. The evidence level, reliability, and credibility of the literature were evaluated using the evidence pyramid method, which considers the article type, impact factor, and journal citation report (JCR) partition. RESULTS A total of 372 articles were collected, of which 129 articles fit the inclusion criteria and 44% were at the top of the evidence pyramid hierarchy; 50% were in the first quarter of the JCR partitions. 114 articles provided specific neural and hormonal evidence of light therapy and were further divided into three groups: 37% were related to circadian regulation circuits, 27% were related to emotional regulation circuits, and 36% were related to hormones. CONCLUSIONS First, neural and hormonal light-active pathways for alleviating sleep disturbance or depression were identified, based on which the neural correlates of SDCD were located. Second, the light responses and interactions of hormones were reviewed and summarized, which also provided a way to alleviate SDCD. Finally, the light-active LHb and SCN exert extensive regulation impacts on the circadian and emotional circuits and hormones, forming a dual-core system for alleviating SDCD.
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Affiliation(s)
- Chen Yaodong
- School of Architecture, Southwest JiaoTong University, Chengdu, China
| | - Yingzi Zhang
- School of Architecture, Southwest JiaoTong University, Chengdu, China
| | - Guo Feng
- Psychological Research and Counseling Center, Southwest Jiaotong Univerisity, Chengdu, China
| | - Yuanfang Lei
- School of Architecture, Southwest JiaoTong University, Chengdu, China
| | - Qiuping Liu
- School of Architecture, Southwest JiaoTong University, Chengdu, China
| | - Yang Liu
- School of Architecture, Southwest JiaoTong University, Chengdu, China
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Ocampo-Espindola JL, Nikhil KL, Li JS, Herzog ED, Kiss IZ. Synchronization, clustering, and weak chimeras in a densely coupled transcription-based oscillator model for split circadian rhythms. CHAOS (WOODBURY, N.Y.) 2023; 33:083105. [PMID: 37535024 PMCID: PMC10403273 DOI: 10.1063/5.0156135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 07/08/2023] [Indexed: 08/04/2023]
Abstract
The synchronization dynamics for the circadian gene expression in the suprachiasmatic nucleus is investigated using a transcriptional circadian clock gene oscillator model. With global coupling in constant dark (DD) conditions, the model exhibits a one-cluster phase synchronized state, in dim light (dim LL), bistability between one- and two-cluster states and in bright LL, a two-cluster state. The two-cluster phase synchronized state, where some oscillator pairs synchronize in-phase, and some anti-phase, can explain the splitting of the circadian clock, i.e., generation of two bouts of daily activities with certain species, e.g., with hamsters. The one- and two-cluster states can be reached by transferring the animal from DD or bright LL to dim LL, i.e., the circadian synchrony has a memory effect. The stability of the one- and two-cluster states was interpreted analytically by extracting phase models from the ordinary differential equation models. In a modular network with two strongly coupled oscillator populations with weak intragroup coupling, with appropriate initial conditions, one group is synchronized to the one-cluster state and the other group to the two-cluster state, resulting in a weak-chimera state. Computational modeling suggests that the daily rhythms in sleep-wake depend on light intensity acting on bilateral networks of suprachiasmatic nucleus (SCN) oscillators. Addition of a network heterogeneity (coupling between the left and right SCN) allowed the system to exhibit chimera states. The simulations can guide experiments in the circadian rhythm research to explore the effect of light intensity on the complexities of circadian desynchronization.
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Affiliation(s)
| | - K. L. Nikhil
- Department of Biology, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130-4899, USA
| | - Jr-Shin Li
- Department of Electrical and Systems Engineering, Washington University in St Louis, 1 Brookings Drive, St. Louis, Missouri 63130, USA
| | - Erik D. Herzog
- Department of Biology, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130-4899, USA
| | - István Z. Kiss
- Department of Chemistry, Saint Louis University, 3501 Laclede Ave., St. Louis, Missouri 63103, USA
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4
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Evans JA, Schwartz WJ. On the origin and evolution of the dual oscillator model underlying the photoperiodic clockwork in the suprachiasmatic nucleus. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2023:10.1007/s00359-023-01659-1. [PMID: 37481773 PMCID: PMC10924288 DOI: 10.1007/s00359-023-01659-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 07/07/2023] [Accepted: 07/13/2023] [Indexed: 07/25/2023]
Abstract
Decades have now passed since Colin Pittendrigh first proposed a model of a circadian clock composed of two coupled oscillators, individually responsive to the rising and setting sun, as a flexible solution to the challenge of behavioral and physiological adaptation to the changing seasons. The elegance and predictive power of this postulation has stimulated laboratories around the world in searches to identify and localize such hypothesized evening and morning oscillators, or sets of oscillators, in insects, rodents, and humans, with experimental designs and approaches keeping pace over the years with technological advances in biology and neuroscience. Here, we recount the conceptual origin and highlight the subsequent evolution of this dual oscillator model for the circadian clock in the mammalian suprachiasmatic nucleus; and how, despite our increasingly sophisticated view of this multicellular pacemaker, Pittendrigh's binary conception has remained influential in our clock models and metaphors.
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Affiliation(s)
- Jennifer A Evans
- Department of Biomedical Sciences, College of Health Sciences, Marquette University, Milwaukee, WI, USA.
| | - William J Schwartz
- Department of Neurology, Dell Medical School, The University of Texas at Austin, Austin, TX, USA
- Groningen Institute for Evolutionary Life Sciences, Faculty of Science and Engineering, University of Groningen, Groningen, The Netherlands
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Qian J, Morris CJ, Phillips AJK, Li P, Rahman SA, Wang W, Hu K, Arendt J, Czeisler CA, Scheer FAJL. Unanticipated daytime melatonin secretion on a simulated night shift schedule generates a distinctive 24-h melatonin rhythm with antiphasic daytime and nighttime peaks. J Pineal Res 2022; 72:e12791. [PMID: 35133678 PMCID: PMC8930611 DOI: 10.1111/jpi.12791] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 01/31/2022] [Accepted: 02/02/2022] [Indexed: 11/29/2022]
Abstract
The daily rhythm of plasma melatonin concentrations is typically unimodal, with one broad peak during the circadian night and near-undetectable levels during the circadian day. Light at night acutely suppresses melatonin secretion and phase shifts its endogenous circadian rhythm. In contrast, exposure to darkness during the circadian day has not generally been reported to increase circulating melatonin concentrations acutely. Here, in a highly-controlled simulated night shift protocol with 12-h inverted behavioral/environmental cycles, we unexpectedly found that circulating melatonin levels were significantly increased during daytime sleep (p < .0001). This resulted in a secondary melatonin peak during the circadian day in addition to the primary peak during the circadian night, when sleep occurred during the circadian day following an overnight shift. This distinctive diurnal melatonin rhythm with antiphasic peaks could not be readily anticipated from the behavioral/environmental factors in the protocol (e.g., light exposure, posture, diet, activity) or from current mathematical model simulations of circadian pacemaker output. The observation, therefore, challenges our current understanding of underlying physiological mechanisms that regulate melatonin secretion. Interestingly, the increase in melatonin concentration observed during daytime sleep was positively correlated with the change in timing of melatonin nighttime peak (p = .002), but not with the degree of light-induced melatonin suppression during nighttime wakefulness (p = .92). Both the increase in daytime melatonin concentrations and the change in the timing of the nighttime peak became larger after repeated exposure to simulated night shifts (p = .002 and p = .006, respectively). Furthermore, we found that melatonin secretion during daytime sleep was positively associated with an increase in 24-h glucose and insulin levels during the night shift protocol (p = .014 and p = .027, respectively). Future studies are needed to elucidate the key factor(s) driving the unexpected daytime melatonin secretion and the melatonin rhythm with antiphasic peaks during shifted sleep/wake schedules, the underlying mechanisms of their relationship with glucose metabolism, and the relevance for diabetes risk among shift workers.
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Affiliation(s)
- Jingyi Qian
- Medical Chronobiology Program, Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
| | - Christopher J Morris
- Medical Chronobiology Program, Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
| | - Andrew JK Phillips
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Melbourne, Victoria, Australia
| | - Peng Li
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
- Medical Biodynamics Program, Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
| | - Shadab A Rahman
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
| | - Wei Wang
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
| | - Kun Hu
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
- Medical Biodynamics Program, Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
| | - Josephine Arendt
- School of Biological Sciences, University of Surrey, Guildford, Surrey, United Kingdom
| | - Charles A Czeisler
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
| | - Frank AJL Scheer
- Medical Chronobiology Program, Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
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Kiss DS, Toth I, Jocsak G, Barany Z, Bartha T, Frenyo LV, Horvath TL, Zsarnovszky A. Functional Aspects of Hypothalamic Asymmetry. Brain Sci 2020; 10:brainsci10060389. [PMID: 32575391 PMCID: PMC7349050 DOI: 10.3390/brainsci10060389] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/08/2020] [Accepted: 06/16/2020] [Indexed: 01/12/2023] Open
Abstract
Anatomically, the brain is a symmetric structure. However, growing evidence suggests that certain higher brain functions are regulated by only one of the otherwise duplicated (and symmetric) brain halves. Hemispheric specialization correlates with phylogeny supporting intellectual evolution by providing an ergonomic way of brain processing. The more complex the task, the higher are the benefits of the functional lateralization (all higher functions show some degree of lateralized task sharing). Functional asymmetry has been broadly studied in several brain areas with mirrored halves, such as the telencephalon, hippocampus, etc. Despite its paired structure, the hypothalamus has been generally considered as a functionally unpaired unit, nonetheless the regulation of a vast number of strongly interrelated homeostatic processes are attributed to this relatively small brain region. In this review, we collected all available knowledge supporting the hypothesis that a functional lateralization of the hypothalamus exists. We collected and discussed findings from previous studies that have demonstrated lateralized hypothalamic control of the reproductive functions and energy expenditure. Also, sporadic data claims the existence of a partial functional asymmetry in the regulation of the circadian rhythm, body temperature and circulatory functions. This hitherto neglected data highlights the likely high-level ergonomics provided by such functional asymmetry.
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Affiliation(s)
- David Sandor Kiss
- Department of Physiology and Biochemistry, University of Veterinary Medicine, 1078 Budapest, Hungary; (I.T.); (G.J.); (Z.B.); (T.B.); (L.V.F.)
- Correspondence: ; Tel.: +36-1478-4247 or +36-1478-8406
| | - Istvan Toth
- Department of Physiology and Biochemistry, University of Veterinary Medicine, 1078 Budapest, Hungary; (I.T.); (G.J.); (Z.B.); (T.B.); (L.V.F.)
| | - Gergely Jocsak
- Department of Physiology and Biochemistry, University of Veterinary Medicine, 1078 Budapest, Hungary; (I.T.); (G.J.); (Z.B.); (T.B.); (L.V.F.)
| | - Zoltan Barany
- Department of Physiology and Biochemistry, University of Veterinary Medicine, 1078 Budapest, Hungary; (I.T.); (G.J.); (Z.B.); (T.B.); (L.V.F.)
| | - Tibor Bartha
- Department of Physiology and Biochemistry, University of Veterinary Medicine, 1078 Budapest, Hungary; (I.T.); (G.J.); (Z.B.); (T.B.); (L.V.F.)
| | - Laszlo V. Frenyo
- Department of Physiology and Biochemistry, University of Veterinary Medicine, 1078 Budapest, Hungary; (I.T.); (G.J.); (Z.B.); (T.B.); (L.V.F.)
| | - Tamas L. Horvath
- Department of Animal Physiology and Animal Health, Szent Istvan University, Faculty of Agricultural and Environmental Sciences, 2100 Gödöllő, Hungary; (T.L.H.); (A.Z.)
- Division of Comparative Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Attila Zsarnovszky
- Department of Animal Physiology and Animal Health, Szent Istvan University, Faculty of Agricultural and Environmental Sciences, 2100 Gödöllő, Hungary; (T.L.H.); (A.Z.)
- Division of Comparative Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
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7
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Kiss DS, Toth I, Jocsak G, Bartha T, Frenyo LV, Barany Z, Horvath TL, Zsarnovszky A. Metabolic Lateralization in the Hypothalamus of Male Rats Related to Reproductive and Satiety States. Reprod Sci 2020; 27:1197-1205. [PMID: 32046448 PMCID: PMC7181557 DOI: 10.1007/s43032-019-00131-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 10/21/2019] [Indexed: 01/12/2023]
Abstract
The hypothalamus is the main regulatory center of many homeostatic processes, such as reproduction, food intake, and sleep-wake behavior. Recent findings show that there is a strongly interdependent side-linked localization of hypothalamic functions between the left and right hemispheres. The goal of the present study was to trace functional asymmetry of the hypothalamus related to the regulation of food intake and reproduction, in male rodents. Subjects were examined through measurements of mitochondrial metabolism ex vivo. Impact of gonadectomy and scheduled feeding was tested on the modulation of hypothalamic metabolic asymmetry. Results show that in male rats, functional lateralization of the hypothalamus can be attributed to the satiety state rather than to reproductive control. Fasting caused left-sided metabolic dominance, while satiety was linked to the right hemisphere; trends and direction in sided dominance gradually followed the changes in satiety state. Our findings revealed satiety state-dependent metabolic differences between the two hypothalamic hemispheres. It is therefore concluded that, at least in male rats, the hypothalamic hemispheres control the satiety state-related functions in an asymmetric manner.
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Affiliation(s)
- David S Kiss
- Department of Physiology and Biochemistry, University of Veterinary Medicine, Istvan u. 2, Budapest, 1078, Hungary.
| | - Istvan Toth
- Department of Physiology and Biochemistry, University of Veterinary Medicine, Istvan u. 2, Budapest, 1078, Hungary
| | - Gergely Jocsak
- Department of Physiology and Biochemistry, University of Veterinary Medicine, Istvan u. 2, Budapest, 1078, Hungary
| | - Tibor Bartha
- Department of Physiology and Biochemistry, University of Veterinary Medicine, Istvan u. 2, Budapest, 1078, Hungary
| | - Laszlo V Frenyo
- Department of Physiology and Biochemistry, University of Veterinary Medicine, Istvan u. 2, Budapest, 1078, Hungary
| | - Zoltan Barany
- Department of Physiology and Biochemistry, University of Veterinary Medicine, Istvan u. 2, Budapest, 1078, Hungary
| | - Tamas L Horvath
- Department of Animal Physiology and Animal Health, Faculty of Agricultural and Environmental Sciences, Szent Istvan University, Pater Karoly u. 1, Godollo, 2100, Hungary.,Department of Comparative Medicine, Yale University School of Medicine, 310 Cedar Street, New Haven, CT, 06520-8016, USA
| | - Attila Zsarnovszky
- Department of Animal Physiology and Animal Health, Faculty of Agricultural and Environmental Sciences, Szent Istvan University, Pater Karoly u. 1, Godollo, 2100, Hungary.,Department of Comparative Medicine, Yale University School of Medicine, 310 Cedar Street, New Haven, CT, 06520-8016, USA
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8
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Aizawa H, Zhu M. Toward an understanding of the habenula's various roles in human depression. Psychiatry Clin Neurosci 2019; 73:607-612. [PMID: 31131942 DOI: 10.1111/pcn.12892] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 05/17/2019] [Accepted: 05/22/2019] [Indexed: 02/07/2023]
Abstract
The habenula is an evolutionarily conserved structure in the vertebrate brain. Lesion and electrophysiological studies in animals have suggested that it is involved in the regulation of monoaminergic activity through projection to the brain stem nuclei. Since studies in animal models of depression and human functional imaging have indicated that increased activity of the habenula is associated with depressive phenotypes, this structure has attracted a surge of interest in neuroscience research. According to pathway- and cell-type-specific dissection of habenular function in animals, we have begun to understand how the heterogeneity of the habenula accounts for alteration of diverse physiological functions in depression. Indeed, recent studies have revealed that the subnuclei embedded in the habenula show a wide variety of molecular profiles not only in neurons but also in glial cells implementing the multifaceted regulatory mechanism for output from the habenula. In this review, we overview the known facts on mediolateral subdivision in the habenular structure, then discuss heterogeneity of the habenular structure from the anatomical and functional viewpoint to understand its emerging role in diverse neural functions relevant to depressive phenotypes. Despite the prevalent use of antidepressants acting on monoamine metabolisms, ~30% of patients with major depression are reported to be treatment-resistant. Thus, cellular mechanisms deciphering such diversity in depressive symptoms would be a promising candidate for the development of new antidepressants.
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Affiliation(s)
- Hidenori Aizawa
- Department of Neurobiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Meina Zhu
- Department of Neurobiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
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9
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Paul JR, Davis JA, Goode LK, Becker BK, Fusilier A, Meador-Woodruff A, Gamble KL. Circadian regulation of membrane physiology in neural oscillators throughout the brain. Eur J Neurosci 2019; 51:109-138. [PMID: 30633846 DOI: 10.1111/ejn.14343] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 12/19/2018] [Accepted: 12/21/2018] [Indexed: 12/21/2022]
Abstract
Twenty-four-hour rhythmicity in physiology and behavior are driven by changes in neurophysiological activity that vary across the light-dark and rest-activity cycle. Although this neural code is most prominent in neurons of the primary circadian pacemaker in the suprachiasmatic nucleus (SCN) of the hypothalamus, there are many other regions in the brain where region-specific function and behavioral rhythmicity may be encoded by changes in electrical properties of those neurons. In this review, we explore the existing evidence for molecular clocks and/or neurophysiological rhythms (i.e., 24 hr) in brain regions outside the SCN. In addition, we highlight the brain regions that are ripe for future investigation into the critical role of circadian rhythmicity for local oscillators. For example, the cerebellum expresses rhythmicity in over 2,000 gene transcripts, and yet we know very little about how circadian regulation drives 24-hr changes in the neural coding responsible for motor coordination. Finally, we conclude with a discussion of how our understanding of circadian regulation of electrical properties may yield insight into disease mechanisms which may lead to novel chronotherapeutic strategies in the future.
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Affiliation(s)
- Jodi R Paul
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Jennifer A Davis
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Lacy K Goode
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Bryan K Becker
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Allison Fusilier
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Aidan Meador-Woodruff
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Karen L Gamble
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
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10
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Distributions of GABAergic and glutamatergic neurons in the brains of a diurnal and nocturnal rodent. Brain Res 2018; 1700:152-159. [PMID: 30153458 DOI: 10.1016/j.brainres.2018.08.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 07/25/2018] [Accepted: 08/17/2018] [Indexed: 12/26/2022]
Abstract
Light influences the daily patterning of activity by both synchronizing internal clocks to environmental light-dark cycles and acutely modulating arousal states, a process known as masking. Masking responses are completely reversed in diurnal and nocturnal species. In nocturnal rodents, masking is mediated through a subset of intrinsically photosensitive retinal ganglion cells (ipRGCs) whose projections are similar in diurnal and nocturnal rodents. This raises the possibility that differences in responsivity to signals that these cells release might underlie chronotype differences in masking. We explored one aspect of this hypothesis by examining the distribution of excitatory and inhibitory neuronal populations in many ipRGC target areas of a diurnal species (Nile grass rat) and a nocturnal one (Norway rat). We discovered that while many of these regions were very similar in these two species, there were striking differences in the ventral lateral geniculate nucleus (vLGN; higher density of glutamate cells in Norway rats) and in the lateral habenula (LHb; GABAeric cells present in grass rats, but not Norway rats). These patterns raise the possibility that the vLGN and LHb contribute to differences in masking and/or circadian regulation of diurnal and nocturnal species.
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11
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Abstract
Over the past 20years, substantive research has firmly implicated the lateral habenula in myriad neural processes including addiction, depression, and sleep. More recently, evidence has emerged suggesting that the lateral habenula is a component of the brain's intrinsic daily or circadian timekeeping system. This system centers on the master circadian pacemaker in the suprachiasmatic nuclei of the hypothalamus that is synchronized to the external world through environmental light information received directly from the eye. Rhythmic clock gene expression in suprachiasmatic neurons drives variation in their electrical activity enabling communication of temporal information, and the organization of circadian rhythms in downstream targets. Here, we review the evidence implicating the lateral habenula as part of an extended neural circadian system. We consider findings suggesting that the lateral habenula is a recipient of circadian signals from the suprachiasmatic nuclei as well as light information from the eye. Further we examine the proposition that the lateral habenula itself expresses intrinsic clock gene and neuronal rhythms. We then speculate on how circadian information communicated from the lateral habenula could influence activity and function in downstream targets such as the ventral tegmental area and raphe nuclei.
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Affiliation(s)
| | - Hugh D Piggins
- Faculty of Biology, Medicine and Health, University of Manchester, M13 9PT, UK.
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12
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Blancas-Velazquez A, Mendoza J, Garcia AN, la Fleur SE. Diet-Induced Obesity and Circadian Disruption of Feeding Behavior. Front Neurosci 2017; 11:23. [PMID: 28223912 PMCID: PMC5293780 DOI: 10.3389/fnins.2017.00023] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 01/12/2017] [Indexed: 12/13/2022] Open
Abstract
Feeding behavior shows a rhythmic daily pattern, which in nocturnal rodents is observed mainly during the dark period. This rhythmicity is under the influence of the hypothalamic suprachiasmatic nucleus (SCN), the main biological clock. Nevertheless, various studies have shown that in rodent models of obesity, using high-energy diets, the general locomotor activity and feeding rhythms can be disrupted. Here, we review the data on the effects of diet-induced obesity (DIO) on locomotor activity and feeding patterns, as well as the effect on the brain sites within the neural circuitry involved in metabolic and rewarding feeding behavior. In general, DIO may alter locomotor activity by decreasing total activity. On the other hand, DIO largely alters eating patterns, producing increased overall ingestion and number of eating bouts that can extend to the resting period. Furthermore, within the hypothalamic areas, little effect has been reported on the molecular circadian mechanism in DIO animals with ad libitum hypercaloric diets and little or no data exist so far on its effects on the reward system areas. We further discuss the possibility of an uncoupling of metabolic and reward systems in DIO and highlight a gap of circadian and metabolic research that may help to better understand the implications of obesity.
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Affiliation(s)
- Aurea Blancas-Velazquez
- Institute of Cellular and Integrative Neurosciences, Centre National de la Recherche Scientifique UPR-3212, University of StrasbourgStrasbourg, France; Department of Endocrinology and Metabolism, Academic Medical Center, University of AmsterdamAmsterdam, Netherlands; Metabolism and Reward Group, Netherlands Institute for NeuroscienceAmsterdam, Netherlands
| | - Jorge Mendoza
- Institute of Cellular and Integrative Neurosciences, Centre National de la Recherche Scientifique UPR-3212, University of Strasbourg Strasbourg, France
| | - Alexandra N Garcia
- Department of Endocrinology and Metabolism, Academic Medical Center, University of AmsterdamAmsterdam, Netherlands; Metabolism and Reward Group, Netherlands Institute for NeuroscienceAmsterdam, Netherlands
| | - Susanne E la Fleur
- Department of Endocrinology and Metabolism, Academic Medical Center, University of AmsterdamAmsterdam, Netherlands; Metabolism and Reward Group, Netherlands Institute for NeuroscienceAmsterdam, Netherlands
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13
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Zhao Z, Xu H, Liu Y, Mu L, Xiao J, Zhao H. Diurnal Expression of the Per2 Gene and Protein in the Lateral Habenular Nucleus. Int J Mol Sci 2015. [PMID: 26213916 PMCID: PMC4581166 DOI: 10.3390/ijms160816740] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The suprachiasmatic nucleus plays an important role in generating circadian rhythms in mammals. The lateral habenular nucleus (LHb) is closely linked to this structure. Interestingly, the LHb shows a rhythmic firing rate in vivo and in vitro, and sustained oscillation of rhythmic genes in vitro. However, under the in vivo condition, whether rhythmic gene expression in the LHb has circadian rhythms remains unknown. In this study, we examined LHb tissue in rats to determine Period2 (Per2) gene and protein expression at six zeitgeber time points (ZT2, ZT6, ZT10, ZT14, ZT18, and ZT22) in a 12-h light and 12-h dark (LD) environment. We found that in the LD environment, Per2 gene expression and PER2 protein levels in the LHb were higher in the day and lower in the night, showing periodic oscillation, with a peak at ZT10 and a trough at ZT22 (Per2 mRNA) and ZT18 (PER2 protein). We conclude that Per2 expression and PER2 protein levels in the LHb have rhythmic oscillation in vivo. This study provides a basis for further study on the role of the LHb in the circadian rhythm system.
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Affiliation(s)
- Zhigong Zhao
- Department of Physiology, College of Basic Medical Sciences, Jilin University, 126 Xinmin Street, Changchun 130021, China.
| | - Haiyan Xu
- Department of Physiology, College of Basic Medical Sciences, Jilin University, 126 Xinmin Street, Changchun 130021, China.
| | - Yongmao Liu
- Department of Physiology, College of Basic Medical Sciences, Jilin University, 126 Xinmin Street, Changchun 130021, China.
| | - Li Mu
- Department of Physiology, College of Basic Medical Sciences, Jilin University, 126 Xinmin Street, Changchun 130021, China.
| | - Jinyu Xiao
- Department of Physiology, College of Basic Medical Sciences, Jilin University, 126 Xinmin Street, Changchun 130021, China.
| | - Hua Zhao
- Department of Physiology, College of Basic Medical Sciences, Jilin University, 126 Xinmin Street, Changchun 130021, China.
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14
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Mendoza J, Challet E. Circadian insights into dopamine mechanisms. Neuroscience 2014; 282:230-42. [PMID: 25281877 DOI: 10.1016/j.neuroscience.2014.07.081] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 07/22/2014] [Accepted: 07/24/2014] [Indexed: 01/11/2023]
Abstract
Almost every physiological or behavioral process in mammals follows rhythmic patterns, which depend mainly on a master circadian clock located in the hypothalamic suprachiasmatic nucleus (SCN). The dopaminergic (DAergic) system in the brain is principally implicated in motor functions, motivation and drug intake. Interestingly, DA-related parameters and behaviors linked to the motivational and arousal states, show daily rhythms that could be regulated by the SCN or by extra-SCN circadian oscillator(s) modulating DAergic systems. Here we examine what is currently understood about the anatomical and functional central multi-oscillatory circadian system, highlighting how the main SCN clock communicates timing information with other brain clocks to regulate the DAergic system and conversely, how DAergic cues may have feedback effects on the SCN. These studies give new insights into the role of the brain circadian system in DA-related neurologic pathologies, such as Parkinson's disease, attention deficit/hyperactive disorder and drug addiction.
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Affiliation(s)
- J Mendoza
- Institute of Cellular and Integrative Neurosciences, CNRS UPR-3212, University of Strasbourg, 5 rue Blaise Pascal, 67084 Strasbourg cedex, France.
| | - E Challet
- Institute of Cellular and Integrative Neurosciences, CNRS UPR-3212, University of Strasbourg, 5 rue Blaise Pascal, 67084 Strasbourg cedex, France
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15
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Silver R, Kriegsfeld LJ. Circadian rhythms have broad implications for understanding brain and behavior. Eur J Neurosci 2014; 39:1866-80. [PMID: 24799154 DOI: 10.1111/ejn.12593] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 03/14/2014] [Accepted: 03/19/2014] [Indexed: 12/28/2022]
Abstract
Circadian rhythms are generated by an endogenously organized timing system that drives daily rhythms in behavior, physiology and metabolism. In mammals, the suprachiasmatic nucleus (SCN) of the hypothalamus is the locus of a master circadian clock. The SCN is synchronized to environmental changes in the light:dark cycle by direct, monosynaptic innervation via the retino-hypothalamic tract. In turn, the SCN coordinates the rhythmic activities of innumerable subordinate clocks in virtually all bodily tissues and organs. The core molecular clockwork is composed of a transcriptional/post-translational feedback loop in which clock genes and their protein products periodically suppress their own transcription. This primary loop connects to downstream output genes by additional, interlocked transcriptional feedback loops to create tissue-specific 'circadian transcriptomes'. Signals from peripheral tissues inform the SCN of the internal state of the organism and the brain's master clock is modified accordingly. A consequence of this hierarchical, multilevel feedback system is that there are ubiquitous effects of circadian timing on genetic and metabolic responses throughout the body. This overview examines landmark studies in the history of the study of circadian timing system, and highlights our current understanding of the operation of circadian clocks with a focus on topics of interest to the neuroscience community.
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Affiliation(s)
- Rae Silver
- Department of Psychology, Barnard College, Columbia University, New York, NY, USA; Department of Psychology, Columbia University, Mail Code 5501, 1190 Amsterdam Avenue, New York, NY, 10027, USA; Department of Pathology and Cell Biology, Columbia University Health Sciences, New York, NY, USA
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16
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Kriegsfeld LJ. Circadian regulation of kisspeptin in female reproductive functioning. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 784:385-410. [PMID: 23550016 DOI: 10.1007/978-1-4614-6199-9_18] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Female reproductive functioning requires the precise temporal -organization of numerous neuroendocrine events by a master circadian brain clock located in the suprachiasmatic nucleus. Across species, including humans, disruptions to circadian timing result in pronounced deficits in ovulation and fecundity. The present chapter provides an overview of the circadian control of female reproduction, underscoring the significance of kisspeptin as a key locus of integration for circadian and steroidal signaling necessary for the initiation of ovulation.
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Affiliation(s)
- Lance J Kriegsfeld
- Department of Psychology, University of California, Berkeley, CA 94720-1650, USA.
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17
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Butler MP, Rainbow MN, Rodriguez E, Lyon SM, Silver R. Twelve-hour days in the brain and behavior of split hamsters. Eur J Neurosci 2012; 36:2556-66. [PMID: 22703520 DOI: 10.1111/j.1460-9568.2012.08166.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Hamsters will spontaneously 'split' and exhibit two rest-activity cycles each day when housed in constant light (LL). The suprachiasmatic nucleus (SCN) is the locus of a brain clock organizing circadian rhythmicity. In split hamsters, the right and left SCN oscillate 12 h out of phase with each other, and the twice-daily locomotor bouts alternately correspond to one or the other. This unique configuration of the circadian system is useful for investigation of SCN communication to efferent targets. To track phase and period in the SCN and its targets, we measured wheel-running and FOS expression in the brains of split and unsplit hamsters housed in LL or light-dark cycles. The amount and duration of activity before splitting were correlated with latency to split, suggesting behavioral feedback to circadian organization. LL induced a robust rhythm in the SCN core, regardless of splitting. The split hamsters' SCN exhibited 24-h rhythms of FOS that cycled in antiphase between left and right sides and between core and shell subregions. In contrast, the medial preoptic area, paraventricular nucleus of the hypothalamus, dorsomedial hypothalamus and orexin-A neurons all exhibited 12-h rhythms of FOS expression, in-phase between hemispheres, with some detectable right-left differences in amplitude. Importantly, in all conditions studied, the onset of FOS expression in targets occurred at a common phase reference point of the SCN oscillation, suggesting that each SCN may signal these targets once daily. Finally, the transduction of 24-h SCN rhythms to 12-h extra-SCN rhythms indicates that each SCN signals both ipsilateral and contralateral targets.
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Affiliation(s)
- Matthew P Butler
- Department of Psychology, Columbia University, New York, NY, USA
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18
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Schroder S, Herzog ED, Kiss IZ. Transcription-based oscillator model for light-induced splitting as antiphase circadian gene expression in the suprachiasmatic nuclei. J Biol Rhythms 2012; 27:79-90. [PMID: 22306976 DOI: 10.1177/0748730411429659] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Daily locomotor patterns of a variety of organisms have been interpreted as driven by dual circadian oscillators. Yet, in mammals, cellular data have revealed many circadian oscillators in the bilateral suprachiasmatic nucleus (SCN). To test how large numbers of oscillators could respond to environmental cues as a pair of oscillators, the authors developed a computational model composed of 2 groups of oscillators with strong local interactions and with weaker coupling between the 2 groups. Unlike previous models that assumed that light affects the timing or polarity of coupling between a pair of oscillators, this simulation assumed that light increased the transcription rate of a clock gene and consequently altered circadian properties of individual cells. In constant dark, weak local (within each of the 2 groups) and distant (between group) coupling established in-phase oscillations and a typical single bout of daily activity. In constant light, local synchrony developed only if coupling was strong and resulted in antiphase synchrony between the 2 groups and bimodal daily activity reminiscent of split behavior. These numerical simulations thus showed that splitting behavior can develop with increased light intensity without structural changes in the coupling topology or sign. Instead, the authors propose that light changes intrinsic oscillator properties through the increase of maximal transcription rate of a clock gene, so that as light intensity increases, the output of the coupled network transitions from a single bout of activity through irregular beating to 2 bouts and, in bright constant light, arrhythmicity.
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Affiliation(s)
- Sondra Schroder
- Department of Chemistry, Saint Louis University, St. Louis, MO, USA
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19
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Lilley TR, Wotus C, Taylor D, Lee JM, de la Iglesia HO. Circadian regulation of cortisol release in behaviorally split golden hamsters. Endocrinology 2012; 153:732-8. [PMID: 22128030 PMCID: PMC3275398 DOI: 10.1210/en.2011-1624] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 11/03/2011] [Indexed: 11/19/2022]
Abstract
The master circadian clock located within the hypothalamic suprachiasmatic nucleus (SCN) is necessary for the circadian rhythm of glucocorticoid (GC) release. The pathways by which the SCN sustains rhythmic GC release remain unclear. We studied the circadian regulation of cortisol release in the behaviorally split golden hamster, in which the single bout of circadian locomotor activity splits into two bouts approximately 12 h apart after exposing the animals to constant light conditions. We show that unsplit control hamsters present a single peak of cortisol release that is concomitant with a single peak of ACTH release. In contrast, split hamsters show two peaks of cortisol release that are approximately 12 h appart and are appropriately phased to each locomotor activity bout but surprisingly do not rely on rhythmic release of ACTH. Our results are consistent with a model in which the circadian pacemaker within the SCN regulates the circadian release of GC via input to the hypothalamo-pituitary-adrenal axis and via a second regulatory pathway, which likely involves sympathetic innervation of the adrenal and can operate even in the absence of ACTH circadian rhythmic release. Furthermore, we show that although the overall 24-h cortisol output in split hamsters is lower than in unsplit controls, split hamsters release constant low levels of ACTH. This result suggests that the timing, rather than the absolute amount, of cortisol release is more critical for the induction of negative feedback effects that regulate the hypothalamo-pituitary-adrenal axis.
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Affiliation(s)
- Travis R Lilley
- Department of Biology, University of Washington, Box 351800, Seattle, Washington 98195-1800, USA
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20
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Williams WP, Kriegsfeld LJ. Circadian control of neuroendocrine circuits regulating female reproductive function. Front Endocrinol (Lausanne) 2012; 3:60. [PMID: 22661968 PMCID: PMC3356853 DOI: 10.3389/fendo.2012.00060] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Accepted: 04/13/2012] [Indexed: 01/14/2023] Open
Abstract
Female reproduction requires the precise temporal organization of interacting, estradiol-sensitive neural circuits that converge to optimally drive hypothalamo-pituitary-gonadal (HPG) axis functioning. In mammals, the master circadian pacemaker in the suprachiasmatic nucleus (SCN) of the anterior hypothalamus coordinates reproductively relevant neuroendocrine events necessary to maximize reproductive success. Likewise, in species where periods of fertility are brief, circadian oversight of reproductive function ensures that estradiol-dependent increases in sexual motivation coincide with ovulation. Across species, including humans, disruptions to circadian timing (e.g., through rotating shift work, night shift work, poor sleep hygiene) lead to pronounced deficits in ovulation and fecundity. Despite the well-established roles for the circadian system in female reproductive functioning, the specific neural circuits and neurochemical mediators underlying these interactions are not fully understood. Most work to date has focused on the direct and indirect communication from the SCN to the gonadotropin-releasing hormone (GnRH) system in control of the preovulatory luteinizing hormone (LH) surge. However, the same clock genes underlying circadian rhythms at the cellular level in SCN cells are also common to target cell populations of the SCN, including the GnRH neuronal network. Exploring the means by which the master clock synergizes with subordinate clocks in GnRH cells and its upstream modulatory systems represents an exciting opportunity to further understand the role of endogenous timing systems in female reproduction. Herein we provide an overview of the state of knowledge regarding interactions between the circadian timing system and estradiol-sensitive neural circuits driving GnRH secretion and the preovulatory LH surge.
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Affiliation(s)
- Wilbur P. Williams
- Department of Psychology, Helen Wills Neuroscience Institute, University of CaliforniaBerkeley, CA, USA
| | - Lance J. Kriegsfeld
- Department of Psychology, Helen Wills Neuroscience Institute, University of CaliforniaBerkeley, CA, USA
- *Correspondence: Lance J. Kriegsfeld, Neurobiology Laboratory, Department of Psychology, Helen Wills Neuroscience Institute, University of California, 3210 Tolman Hall, #1650, Berkeley, CA 94720-1650, USA. e-mail:
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21
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Blum I, Lamont EW, Abizaid A. Competing clocks: Metabolic status moderates signals from the master circadian pacemaker. Neurosci Biobehav Rev 2012; 36:254-70. [DOI: 10.1016/j.neubiorev.2011.06.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 05/27/2011] [Accepted: 06/02/2011] [Indexed: 11/28/2022]
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22
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Nighttime dim light exposure alters the responses of the circadian system. Neuroscience 2010; 170:1172-8. [PMID: 20705120 DOI: 10.1016/j.neuroscience.2010.08.009] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 08/02/2010] [Accepted: 08/04/2010] [Indexed: 12/11/2022]
Abstract
The daily light dark cycle is the most salient entraining factor for the circadian system. However, in modern society, darkness at night is vanishing as light pollution steadily increases. The impact of brighter nights on wild life ecology and human physiology is just now being recognized. In the present study, we tested the possible detrimental effects of dim light exposure on the regulation of circadian rhythms, using CD1 mice housed in light/dim light (LdimL, 300 lux:20 lux) or light/dark (LD, 300 lux:1 lux) conditions. We first examined the expression of clock genes in the suprachiasmatic nucleus (SCN), the locus of the principal brain clock, in the animals of the LD and LdimL groups. Under the entrained condition, there was no difference in PER1 peak expression between the two groups, but at the trough of the PER 1 rhythm, there was an increase in PER1 in the LdimL group, indicating a decrease in the amplitude of the PER1 rhythm. After a brief light exposure (30 min, 300 lux) at night, the light-induced expression of mPer1 and mPer2 genes was attenuated in the SCN of LdimL group. Next, we examined the behavioral rhythms by monitoring wheel-running activity to determine whether the altered responses in the SCN of LdimL group have behavioral consequence. Compared to the LD controls, the LdimL group showed increased daytime activity. After being released into constant darkness, the LdimL group displayed shorter free-running periods. Furthermore, following the light exposure, the phase shifting responses were smaller in the LdimL group. The results indicate that nighttime dim light exposure can cause functional changes of the circadian system, and suggest that altered circadian function could be one of the mechanisms underlying the adverse effects of light pollution on wild life ecology and human physiology.
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23
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Guilding C, Hughes ATL, Piggins HD. Circadian oscillators in the epithalamus. Neuroscience 2010; 169:1630-9. [PMID: 20547209 PMCID: PMC2928449 DOI: 10.1016/j.neuroscience.2010.06.015] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 06/04/2010] [Accepted: 06/08/2010] [Indexed: 12/28/2022]
Abstract
The habenula complex is implicated in a range of cognitive, emotional and reproductive behaviors, and recently this epithalamic structure was suggested to be a component of the brain's circadian system. Circadian timekeeping is driven in cells by the cyclical activity of core clock genes and proteins such as per2/PER2. There are currently no reports of rhythmic clock gene/protein expression in the habenula and therefore the question of whether this structure has an intrinsic molecular clock remains unresolved. Here, using videomicroscopy imaging and photon-counting of a PER2::luciferase (LUC) fusion protein together with multiunit electrophysiological recordings, we tested the endogenous circadian properties of the mouse habenula in vitro. We show that a circadian oscillator is localized primarily to the medial portion of the lateral habenula. Rhythms in PER2:: LUC bioluminescence here are visualized in single cells and oscillations continue in the presence of the sodium channel blocker, tetrodotoxin, indicating that individual cells have intrinsic timekeeping properties. Ependymal cells lining the dorsal third ventricle also express circadian oscillations of PER2. These findings establish that neurons and non-neuronal cells in the epithalamus express rhythms in cellular and molecular activities, indicating a role for circadian oscillators in the temporal regulation of habenula controlled processes and behavior.
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Affiliation(s)
- C Guilding
- Faculty of Life Sciences, University of Manchester, Manchester, UK
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24
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Yan L, Silver R, Gorman M. Reorganization of suprachiasmatic nucleus networks under 24-h LDLD conditions. J Biol Rhythms 2010; 25:19-27. [PMID: 20075297 DOI: 10.1177/0748730409352054] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The suprachiasmatic nucleus (SCN), locus of the master circadian clock in the brain, is comprised of multioscillator neural networks that are highly plastic in responding to environmental lighting conditions. Under a 24-h light:dark:light:dark (LDLD) cycle, hamsters bifurcate their circadian locomotor activity such that wheel running occurs in each of the 2 daily dark periods with complete inactivity in between. In the present study, we explored the neural underpinning of this behavioral bifurcation. Using calbindin (CalB)- containing cells of the SCN as a regional marker, we characterized PER1 and c-FOS expression in the core and shell SCN subregions. In LD-housed animals, it is known that PER1 and c-FOS in the core and shell region are in phase with each other. In contrast, in behaviorally bifurcated animals housed in LDLD, the core and shell SCN exhibit antiphase rhythms of PER1. Furthermore, cells in the core show high FOS expression in each photophase of the LDLD cycle. The activation of FOS in the core is light driven and disappears rapidly when the photophase is replaced by darkness. The results suggest that bifurcated activity bouts in daytime and nighttime are associated with oscillating groups of cells in the core and shell subregions, respectively, and support the notion that reorganization of SCN networks underlies changes in behavioral responses under different environmental lighting conditions.
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Affiliation(s)
- Lily Yan
- Department of Psychology Neuroscience Program, Michigan State University, East Lansing, MI 48824 , USA.
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25
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Mendoza J, Pévet P, Challet E. Entrainment and coupling of the hamster suprachiasmatic clock by daily dark pulses. J Neurosci Res 2009; 87:758-65. [DOI: 10.1002/jnr.21887] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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26
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Indic P, Schwartz WJ, Paydarfar D. Design principles for phase-splitting behaviour of coupled cellular oscillators: clues from hamsters with 'split' circadian rhythms. J R Soc Interface 2008; 5:873-83. [PMID: 18077247 PMCID: PMC2607461 DOI: 10.1098/rsif.2007.1248] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Nonlinear interactions among coupled cellular oscillators are likely to underlie a variety of complex rhythmic behaviours. Here we consider the case of one such behaviour, a doubling of rhythm frequency caused by the spontaneous splitting of a population of synchronized oscillators into two subgroups each oscillating in anti-phase (phase-splitting). An example of biological phase-splitting is the frequency doubling of the circadian locomotor rhythm in hamsters housed in constant light, in which the pacemaker in the suprachiasmatic nucleus (SCN) is reconfigured with its left and right halves oscillating in anti-phase. We apply the theory of coupled phase oscillators to show that stable phase-splitting requires the presence of negative coupling terms, through delayed and/or inhibitory interactions. We also find that the inclusion of real biological constraints (that the SCN contains a finite number of non-identical noisy oscillators) implies the existence of an underlying non-uniform network architecture, in which the population of oscillators must interact through at least two types of connections. We propose that a key design principle for the frequency doubling of a population of biological oscillators is inhomogeneity of oscillator coupling.
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Affiliation(s)
- Premananda Indic
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01655, USA
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27
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Gibson EM, Humber SA, Jain S, Williams WP, Zhao S, Bentley GE, Tsutsui K, Kriegsfeld LJ. Alterations in RFamide-related peptide expression are coordinated with the preovulatory luteinizing hormone surge. Endocrinology 2008; 149:4958-69. [PMID: 18566114 PMCID: PMC2582915 DOI: 10.1210/en.2008-0316] [Citation(s) in RCA: 170] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The preovulatory LH surge is triggered when the circadian pacemaker, the bilateral suprachiasmatic nucleus (SCN), stimulates the GnRH system in the presence of high estrogen concentrations (positive feedback). Importantly, during the remainder of the estrous cycle, estradiol inhibits LH release via negative feedback. We have recently documented the presence of a novel mammalian RFamide-related peptide (RFRP), a putative gonadotropin-inhibitory hormone (GnIH), that presumably acts upstream of GnRH to modulate the negative feedback effects of estrogen. The present series of studies used female Syrian hamsters to examine the possibility that, in addition to driving the LH surge positively, the SCN concomitantly coordinates the removal of steroid-mediated RFRP inhibition of the gonadotropic axis to permit the surge. We found that the SCN forms close appositions with RFRP cells, suggesting the possibility for direct temporal control of RFRP activity. During the time of the LH surge, immediate-early gene expression is reduced in RFRP cells, and this temporal regulation is estrogen dependent. To determine whether projections from the SCN regulate the timed reduction in activation of the RFRP system, we exploited the phenomenon of splitting. In split animals in which the SCN are active in antiphase, activation of the RFRP system is asymmetrical. Importantly, this asymmetry is opposite to the state of the GnRH system. Together, these findings point to novel circadian control of the RFRP system and potential participation in the circuitry controlling ovulatory function.
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Affiliation(s)
- Erin M Gibson
- Department of Psychology and Helen Wills Neuroscience Institute, 3210 Tolman Hall, 1650, University of California, Berkeley, California 94720-1650, USA
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28
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Abstract
In this contribution to the CNS Spectrums neuroanatomy series, Stefanie Geisler, MD, discusses the lateral habenula (LHb). This nuclear complex is one of the areas of the brain that forms part of the cross-talk between limbic fore-brain and some important ascending modulatory pathways. Situated at the caudal end of the dorsal diencephalon and classically regarded as projecting largely to the brainstem, including the serotoninergic raphe nuclei, the LHb receives afferents from widespread forebrain areas. Therefore, the LHb is able to influence serotonin tone in the brain, and has long interested neuroanatomists as a potential limbic-motor interface. Nonetheless, the LHb was not much discussed outside neuroanatomical circles until recently, when it was discovered that its impact on the mesotelencephalic dopamine system is probably much greater than had been assumed. The LHb has become a hot topic. This article-addresses these developments and emphasizes the clinical relevance of this interesting brain structure.
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29
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Kaur S, Rusak B. Optic enucleation eliminates circadian rhythm shifts induced by stimulating the intergeniculate leaflet in Syrian hamsters. Neurosci Lett 2007; 427:107-11. [DOI: 10.1016/j.neulet.2007.09.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2007] [Revised: 09/11/2007] [Accepted: 09/13/2007] [Indexed: 11/25/2022]
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Yan L, Karatsoreos I, Lesauter J, Welsh DK, Kay S, Foley D, Silver R. Exploring spatiotemporal organization of SCN circuits. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2007; 72:527-41. [PMID: 18419312 PMCID: PMC3281753 DOI: 10.1101/sqb.2007.72.037] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Suprachiasmatic nucleus (SCN) neuroanatomy has been a subject of intense interest since the discovery of the SCN's function as a brain clock and subsequent studies revealing substantial heterogeneity of its component neurons. Understanding the network organization of the SCN has become increasingly relevant in the context of studies showing that its functional circuitry, evident in the spatial and temporal expression of clock genes, can be reorganized by inputs from the internal and external environment. Although multiple mechanisms have been proposed for coupling among SCN neurons, relatively little is known of the precise pattern of SCN circuitry. To explore SCN networks, we examine responses of the SCN to various photic conditions, using in vivo and in vitro studies with associated mathematical modeling to study spatiotemporal changes in SCN activity. We find an orderly and reproducible spatiotemporal pattern of oscillatory gene expression in the SCN, which requires the presence of the ventrolateral core region. Without the SCN core region, behavioral rhythmicity is abolished in vivo, whereas low-amplitude rhythmicity can be detected in SCN slices in vitro, but with loss of normal topographic organization. These studies reveal SCN circuit properties required to signal daily time.
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Affiliation(s)
- L Yan
- Department of Psychology, Columbia University, New York, New York 10027, USA
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Tavakoli-Nezhad M, Schwartz WJ. Hamsters running on time: is the lateral habenula a part of the clock? Chronobiol Int 2006; 23:217-24. [PMID: 16687295 DOI: 10.1080/07420520500521947] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Previous anatomical and physiological studies have implicated the lateral habenula, and especially its medial division (LHbM), as a candidate component of the circadian timing system in rodents. We assayed lateral habenula rhythmicity in rodents using c-FOS immunohistochemistry and found a robust rhythm in immunoreactive cell counts in the LHbM, with higher counts during the dark phase of a light-dark (LD) cycle and during subjective night in constant darkness. We have also observed an obvious asymmetry of c-FOS expression in the LHbM of behaviorally "split" hamsters in constant light, but only during their active phase (when they were running in wheels). Locomotor activity rhythms appear to be regulated by the suprachiasmatic nucleus (SCN) via multiple output pathways, one of which might be diffusible while the other might be neural, involving the lateral habenula.
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Kriegsfeld LJ, Silver R. The regulation of neuroendocrine function: Timing is everything. Horm Behav 2006; 49:557-74. [PMID: 16497305 PMCID: PMC3275441 DOI: 10.1016/j.yhbeh.2005.12.011] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2005] [Revised: 12/06/2005] [Accepted: 12/08/2005] [Indexed: 11/21/2022]
Abstract
Hormone secretion is highly organized temporally, achieving optimal biological functioning and health. The master clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus coordinates the timing of circadian rhythms, including daily control of hormone secretion. In the brain, the SCN drives hormone secretion. In some instances, SCN neurons make direct synaptic connections with neurosecretory neurons. In other instances, SCN signals set the phase of "clock genes" that regulate circadian function at the cellular level within neurosecretory cells. The protein products of these clock genes can also exert direct transcriptional control over neuroendocrine releasing factors. Clock genes and proteins are also expressed in peripheral endocrine organs providing additional modes of temporal control. Finally, the SCN signals endocrine glands via the autonomic nervous system, allowing for rapid regulation via multisynaptic pathways. Thus, the circadian system achieves temporal regulation of endocrine function by a combination of genetic, cellular, and neural regulatory mechanisms to ensure that each response occurs in its correct temporal niche. The availability of tools to assess the phase of molecular/cellular clocks and of powerful tract tracing methods to assess connections between "clock cells" and their targets provides an opportunity to examine circadian-controlled aspects of neurosecretion, in the search for general principles by which the endocrine system is organized.
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Affiliation(s)
- Lance J Kriegsfeld
- Department of Psychology and Helen Wills Neuroscience Institute, 3210 Tolman Hall, #1650, University of California, Berkeley, CA 94720-1650, USA.
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Guglielmotti V, Cristino L. The interplay between the pineal complex and the habenular nuclei in lower vertebrates in the context of the evolution of cerebral asymmetry. Brain Res Bull 2006; 69:475-88. [PMID: 16647576 DOI: 10.1016/j.brainresbull.2006.03.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Revised: 02/24/2006] [Accepted: 03/19/2006] [Indexed: 10/24/2022]
Abstract
This paper presents an overview on the epithalamus of vertebrates, with particular reference to the pineal and to the asymmetrical organization of the habenular nuclei in lower vertebrates. The relationship between the pineal and the habenulae in the course of phylogenesis is here emphasized, taking data in the frog as example. Altogether the data support the hypothesis, put forward also in earlier studies, of a correlation of habenular asymmetry in lower vertebrates with phylogenetic modification of the pineal complex. The present re-visitation was also stimulated by recent data on the asymmetrical expression of Nodal genes, which involves the pineal and habenular structures in zebrafish. The comparative analysis of data, from cyclostomes to mammals, suggests that transformation of epithalamic structures may play an important role in brain evolution. In addition, in mammals, including rodents, a remarkable complexity has evolved in the organization of the habenulae and their functional interactions with the pineal gland. The evolution of these two epithalamic structures seems to open also new perspectives of knowledge on their implication in the regulation of biological rhythms.
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Affiliation(s)
- Vittorio Guglielmotti
- Institute of Cybernetics E. Caianiello, Consiglio Nazionale delle Ricerche, via Campi Flegrei, 34, 80078 Pozzuoli, Naples, Italy.
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