1
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Starnes AN, Jones JR. Inputs and Outputs of the Mammalian Circadian Clock. BIOLOGY 2023; 12:508. [PMID: 37106709 PMCID: PMC10136320 DOI: 10.3390/biology12040508] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 03/16/2023] [Accepted: 03/24/2023] [Indexed: 03/30/2023]
Abstract
Circadian rhythms in mammals are coordinated by the central circadian pacemaker, the suprachiasmatic nucleus (SCN). Light and other environmental inputs change the timing of the SCN neural network oscillator, which, in turn, sends output signals that entrain daily behavioral and physiological rhythms. While much is known about the molecular, neuronal, and network properties of the SCN itself, the circuits linking the outside world to the SCN and the SCN to rhythmic outputs are understudied. In this article, we review our current understanding of the synaptic and non-synaptic inputs onto and outputs from the SCN. We propose that a more complete description of SCN connectivity is needed to better explain how rhythms in nearly all behaviors and physiological processes are generated and to determine how, mechanistically, these rhythms are disrupted by disease or lifestyle.
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Affiliation(s)
| | - Jeff R. Jones
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
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2
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Grassi D, Marraudino M, Garcia-Segura LM, Panzica GC. The hypothalamic paraventricular nucleus as a central hub for the estrogenic modulation of neuroendocrine function and behavior. Front Neuroendocrinol 2022; 65:100974. [PMID: 34995643 DOI: 10.1016/j.yfrne.2021.100974] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 12/18/2021] [Accepted: 12/21/2021] [Indexed: 12/17/2022]
Abstract
Estradiol and hypothalamic paraventricular nucleus (PVN) help coordinate reproduction with body physiology, growth and metabolism. PVN integrates hormonal and neural signals originating in the periphery, generating an output mediated both by its long-distance neuronal projections, and by a variety of neurohormones produced by its magnocellular and parvocellular neurosecretory cells. Here we review the cyto-and chemo-architecture, the connectivity and function of PVN and the sex-specific regulation exerted by estradiol on PVN neurons and on the expression of neurotransmitters, neuromodulators, neuropeptides and neurohormones in PVN. Classical and non-classical estrogen receptors (ERs) are expressed in neuronal afferents to PVN and in specific PVN interneurons, projecting neurons, neurosecretory neurons and glial cells that are involved in the input-output integration and coordination of neurohormonal signals. Indeed, PVN ERs are known to modulate body homeostatic processes such as autonomic functions, stress response, reproduction, and metabolic control. Finally, the functional implications of the estrogenic modulation of the PVN for body homeostasis are discussed.
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Affiliation(s)
- D Grassi
- Department of Anatomy, Histology and Neuroscience, Universidad Autonoma de Madrid, Madrid, Spain
| | - M Marraudino
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Torino, Italy
| | - L M Garcia-Segura
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - G C Panzica
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Torino, Italy; Department of Neuroscience Rita Levi Montalcini, University of Torino, Torino, Italy.
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3
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Hou X, Rong C, Wang F, Liu X, Sun Y, Zhang HT. GABAergic System in Stress: Implications of GABAergic Neuron Subpopulations and the Gut-Vagus-Brain Pathway. Neural Plast 2020; 2020:8858415. [PMID: 32802040 PMCID: PMC7416252 DOI: 10.1155/2020/8858415] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 07/03/2020] [Accepted: 07/06/2020] [Indexed: 02/07/2023] Open
Abstract
Stress can cause a variety of central nervous system disorders, which are critically mediated by the γ-aminobutyric acid (GABA) system in various brain structures. GABAergic neurons have different subsets, some of which coexpress certain neuropeptides that can be found in the digestive system. Accumulating evidence demonstrates that the gut-brain axis, which is primarily regulated by the vagus nerve, is involved in stress, suggesting a communication between the "gut-vagus-brain" pathway and the GABAergic neuronal system. Here, we first summarize the evidence that the GABAergic system plays an essential role in stress responses. In addition, we review the effects of stress on different brain regions and GABAergic neuron subpopulations, including somatostatin, parvalbumin, ionotropic serotonin receptor 5-HT3a, cholecystokinin, neuropeptide Y, and vasoactive intestinal peptide, with regard to signaling events, behavioral changes, and pathobiology of neuropsychiatric diseases. Finally, we discuss the gut-brain bidirectional communications and the connection of the GABAergic system and the gut-vagus-brain pathway.
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Affiliation(s)
- Xueqin Hou
- Institute of Pharmacology, Shandong First Medical University & Shandong Academy of Medical Sciences, Tai'an, Shandong 271016, China
| | - Cuiping Rong
- The Second Clinical Medical College, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China
| | - Fugang Wang
- Institute of Pharmacology, Shandong First Medical University & Shandong Academy of Medical Sciences, Tai'an, Shandong 271016, China
| | - Xiaoqian Liu
- Institute of Pharmacology, Shandong First Medical University & Shandong Academy of Medical Sciences, Tai'an, Shandong 271016, China
| | - Yi Sun
- Institute of Pharmacology, Shandong First Medical University & Shandong Academy of Medical Sciences, Tai'an, Shandong 271016, China
| | - Han-Ting Zhang
- Departments of Neuroscience and Behavioral Medicine & Psychiatry, The Rockefeller Neurosciences Institute, West Virginia University Health Sciences Center, Morgantown, WV 26506, USA
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4
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A hypothalamic circuit for the circadian control of aggression. Nat Neurosci 2018; 21:717-724. [PMID: 29632359 PMCID: PMC5920747 DOI: 10.1038/s41593-018-0126-0] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 02/09/2018] [Indexed: 11/21/2022]
Abstract
“Sundowning” in dementia and Alzheimer’s disease is characterized by early evening agitation and aggression. While such periodicity suggests a circadian origin, whether the circadian clock directly regulates aggressive behavior is unknown. We demonstrate that a daily rhythm in aggression propensity in male mice is gated by GABAergic subparaventricular zone (SPZGABA) neurons, the major postsynaptic targets of the central circadian clock, the suprachiasmatic nucleus (SCN). Optogenetic mapping revealed that SPZGABA neurons receive input from vasoactive intestinal polypeptide SCN neurons and innervate neurons in the ventrolateral part of the ventromedial hypothalamus (VMHvl) known to regulate aggression. Additionally, VMH-projecting dorsal SPZ neurons are more active during early day than early night, and acute chemogenetic inhibition of SPZGABA transmission phase-dependently increases aggression. Finally, SPZGABA-recipient central VMH neurons directly innervate VMHvl neurons and activation of this intra-VMH circuit drove attack behavior. Altogether, we reveal a functional polysynaptic circuit by which the SCN clock regulates aggression.
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5
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Diessler S, Kostic C, Arsenijevic Y, Kawasaki A, Franken P. Rai1 frees mice from the repression of active wake behaviors by light. eLife 2017; 6. [PMID: 28548639 PMCID: PMC5464769 DOI: 10.7554/elife.23292] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 05/24/2017] [Indexed: 12/23/2022] Open
Abstract
Besides its role in vision, light impacts physiology and behavior through circadian and direct (aka ‘masking’) mechanisms. In Smith-Magenis syndrome (SMS), the dysregulation of both sleep-wake behavior and melatonin production strongly suggests impaired non-visual light perception. We discovered that mice haploinsufficient for the SMS causal gene, Retinoic acid induced-1 (Rai1), were hypersensitive to light such that light eliminated alert and active-wake behaviors, while leaving time-spent-awake unaffected. Moreover, variables pertaining to circadian rhythm entrainment were activated more strongly by light. At the input level, the activation of rod/cone and suprachiasmatic nuclei (SCN) by light was paradoxically greatly reduced, while the downstream activation of the ventral-subparaventricular zone (vSPVZ) was increased. The vSPVZ integrates retinal and SCN input and, when activated, suppresses locomotor activity, consistent with the behavioral hypersensitivity to light we observed. Our results implicate Rai1 as a novel and central player in processing non-visual light information, from input to behavioral output. DOI:http://dx.doi.org/10.7554/eLife.23292.001
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Affiliation(s)
- Shanaz Diessler
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Corinne Kostic
- Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, University of Lausanne, Lausanne, Switzerland
| | - Yvan Arsenijevic
- Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, University of Lausanne, Lausanne, Switzerland
| | - Aki Kawasaki
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland.,Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, University of Lausanne, Lausanne, Switzerland
| | - Paul Franken
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
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6
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Fung C, Boesmans W, Cirillo C, Foong JPP, Bornstein JC, Vanden Berghe P. VPAC Receptor Subtypes Tune Purinergic Neuron-to-Glia Communication in the Murine Submucosal Plexus. Front Cell Neurosci 2017; 11:118. [PMID: 28487635 PMCID: PMC5403822 DOI: 10.3389/fncel.2017.00118] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 04/10/2017] [Indexed: 12/20/2022] Open
Abstract
The enteric nervous system (ENS) situated within the gastrointestinal tract comprises an intricate network of neurons and glia which together regulate intestinal function. The exact neuro-glial circuitry and the signaling molecules involved are yet to be fully elucidated. Vasoactive intestinal peptide (VIP) is one of the main neurotransmitters in the gut, and is important for regulating intestinal secretion and motility. However, the role of VIP and its VPAC receptors within the enteric circuitry is not well understood. We investigated this in the submucosal plexus of mouse jejunum using calcium (Ca2+)-imaging. Local VIP application induced Ca2+-transients primarily in neurons and these were inhibited by VPAC1- and VPAC2-antagonists (PG 99-269 and PG 99-465 respectively). These VIP-evoked neural Ca2+-transients were also inhibited by tetrodotoxin (TTX), indicating that they were secondary to action potential generation. Surprisingly, VIP induced Ca2+-transients in glia in the presence of the VPAC2 antagonist. Further, selective VPAC1 receptor activation with the agonist ([K15, R16, L27]VIP(1-7)/GRF(8-27)) predominantly evoked glial responses. However, VPAC1-immunoreactivity did not colocalize with the glial marker glial fibrillary acidic protein (GFAP). Rather, VPAC1 expression was found on cholinergic submucosal neurons and nerve fibers. This suggests that glial responses observed were secondary to neuronal activation. Trains of electrical stimuli were applied to fiber tracts to induce endogenous VIP release. Delayed glial responses were evoked when the VPAC2 antagonist was present. These findings support the presence of an intrinsic VIP/VPAC-initiated neuron-to-glia signaling pathway. VPAC1 agonist-evoked glial responses were inhibited by purinergic antagonists (PPADS and MRS2179), thus demonstrating the involvement of P2Y1 receptors. Collectively, we showed that neurally-released VIP can activate neurons expressing VPAC1 and/or VPAC2 receptors to modulate purine-release onto glia. Selective VPAC1 activation evokes a glial response, whereas VPAC2 receptors may act to inhibit this response. Thus, we identified a component of an enteric neuron-glia circuit that is fine-tuned by endogenous VIP acting through VPAC1- and VPAC2-mediated pathways.
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Affiliation(s)
- Candice Fung
- Department of Physiology, The University of MelbourneParkville, VIC, Australia.,Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
| | - Werend Boesmans
- Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
| | - Carla Cirillo
- Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
| | - Jaime P P Foong
- Department of Physiology, The University of MelbourneParkville, VIC, Australia
| | - Joel C Bornstein
- Department of Physiology, The University of MelbourneParkville, VIC, Australia
| | - Pieter Vanden Berghe
- Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
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7
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Albers HE, Walton JC, Gamble KL, McNeill JK, Hummer DL. The dynamics of GABA signaling: Revelations from the circadian pacemaker in the suprachiasmatic nucleus. Front Neuroendocrinol 2017; 44:35-82. [PMID: 27894927 PMCID: PMC5225159 DOI: 10.1016/j.yfrne.2016.11.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 10/16/2016] [Accepted: 11/22/2016] [Indexed: 12/31/2022]
Abstract
Virtually every neuron within the suprachiasmatic nucleus (SCN) communicates via GABAergic signaling. The extracellular levels of GABA within the SCN are determined by a complex interaction of synthesis and transport, as well as synaptic and non-synaptic release. The response to GABA is mediated by GABAA receptors that respond to both phasic and tonic GABA release and that can produce excitatory as well as inhibitory cellular responses. GABA also influences circadian control through the exclusively inhibitory effects of GABAB receptors. Both GABA and neuropeptide signaling occur within the SCN, although the functional consequences of the interactions of these signals are not well understood. This review considers the role of GABA in the circadian pacemaker, in the mechanisms responsible for the generation of circadian rhythms, in the ability of non-photic stimuli to reset the phase of the pacemaker, and in the ability of the day-night cycle to entrain the pacemaker.
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Affiliation(s)
- H Elliott Albers
- Center for Behavioral Neuroscience, Atlanta, GA 30302, United States; Neuroscience Institute, Georgia State University, Atlanta, GA 30302, United States.
| | - James C Walton
- Center for Behavioral Neuroscience, Atlanta, GA 30302, United States; Neuroscience Institute, Georgia State University, Atlanta, GA 30302, United States
| | - Karen L Gamble
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - John K McNeill
- Center for Behavioral Neuroscience, Atlanta, GA 30302, United States; Neuroscience Institute, Georgia State University, Atlanta, GA 30302, United States
| | - Daniel L Hummer
- Center for Behavioral Neuroscience, Atlanta, GA 30302, United States; Department of Psychology, Morehouse College, Atlanta, GA 30314, United States
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8
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Vosko A, van Diepen HC, Kuljis D, Chiu AM, Heyer D, Terra H, Carpenter E, Michel S, Meijer JH, Colwell CS. Role of vasoactive intestinal peptide in the light input to the circadian system. Eur J Neurosci 2015; 42:1839-48. [PMID: 25885685 DOI: 10.1111/ejn.12919] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Revised: 04/11/2015] [Accepted: 04/13/2015] [Indexed: 12/11/2022]
Abstract
The neuropeptide vasoactive intestinal peptide (VIP) is expressed at high levels in a subset of neurons in the ventral region of the suprachiasmatic nucleus (SCN). While VIP is known to be important for the synchronization of the SCN network, the role of VIP in photic regulation of the circadian system has received less attention. In the present study, we found that the light-evoked increase in electrical activity in vivo was unaltered by the loss of VIP. In the absence of VIP, the ventral SCN still exhibited N-methyl-d-aspartate-evoked responses in a brain slice preparation, although the absolute levels of neural activity before and after treatment were significantly reduced. Next, we used calcium imaging techniques to determine if the loss of VIP altered the calcium influx due to retinohypothalamic tract stimulation. The magnitude of the evoked calcium influx was not reduced in the ventral SCN, but did decline in the dorsal SCN regions. We examined the time course of the photic induction of Period1 in the SCN using in situ hybridization in VIP-mutant mice. We found that the initial induction of Period1 was not reduced by the loss of this signaling peptide. However, the sustained increase in Period1 expression (after 30 min) was significantly reduced. Similar results were found by measuring the light induction of cFOS in the SCN. These findings suggest that VIP is critical for longer-term changes within the SCN circuit, but does not play a role in the acute light response.
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Affiliation(s)
- Andrew Vosko
- Department of Structural Medicine, Rocky Vista University, Parker, CO, USA
| | - Hester C van Diepen
- Laboratory of Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Dika Kuljis
- Department of Psychiatry & Biobehavioral Sciences, University of California - Los Angeles, Los Angeles, CA, 90024, USA
| | - Andrew M Chiu
- Medical Scientist Training Program, Northwestern University, Evanston, IL, USA
| | - Djai Heyer
- Laboratory of Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Huub Terra
- Laboratory of Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Ellen Carpenter
- Department of Psychiatry & Biobehavioral Sciences, University of California - Los Angeles, Los Angeles, CA, 90024, USA
| | - Stephan Michel
- Laboratory of Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Johanna H Meijer
- Laboratory of Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Christopher S Colwell
- Department of Psychiatry & Biobehavioral Sciences, University of California - Los Angeles, Los Angeles, CA, 90024, USA
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9
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Blumberg MS, Gall AJ, Todd WD. The development of sleep-wake rhythms and the search for elemental circuits in the infant brain. Behav Neurosci 2014; 128:250-63. [PMID: 24708298 DOI: 10.1037/a0035891] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Despite the predominance of sleep in early infancy, developmental science has yet to play a major role in shaping concepts and theories about sleep and its associated ultradian and circadian rhythms. Here we argue that developmental analyses help us to elucidate the relative contributions of the brainstem and forebrain to sleep-wake control and to dissect the neural components of sleep-wake rhythms. Developmental analysis also makes it clear that sleep-wake processes in infants are the foundation for those of adults. For example, the infant brainstem alone contains a fundamental sleep-wake circuit that is sufficient to produce transitions among wakefulness, quiet sleep, and active sleep. In addition, consistent with the requirements of a "flip-flop" model of sleep-wake processes, this brainstem circuit supports rapid transitions between states. Later in development, strengthening bidirectional interactions between the brainstem and forebrain contribute to the consolidation of sleep and wake bouts, the elaboration of sleep homeostatic processes, and the emergence of diurnal or nocturnal circadian rhythms. The developmental perspective promoted here critically constrains theories of sleep-wake control and provides a needed framework for the creation of fully realized computational models. Finally, with a better understanding of how this system is constructed developmentally, we will gain insight into the processes that govern its disintegration due to aging and disease.
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Affiliation(s)
| | | | - William D Todd
- Department of Neurology, Beth Israel Deaconess Medical Center
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10
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Physiologically-based modeling of sleep-wake regulatory networks. Math Biosci 2014; 250:54-68. [PMID: 24530893 DOI: 10.1016/j.mbs.2014.01.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 01/23/2014] [Accepted: 01/31/2014] [Indexed: 12/27/2022]
Abstract
Mathematical modeling has played a significant role in building our understanding of sleep-wake and circadian behavior. Over the past 40 years, phenomenological models, including the two-process model and oscillator models, helped frame experimental results and guide progress in understanding the interaction of homeostatic and circadian influences on sleep and understanding the generation of rapid eye movement sleep cycling. Recent advances in the clarification of the neural anatomy and physiology involved in the regulation of sleep and circadian rhythms have motivated the development of more detailed and physiologically-based mathematical models that extend the approach introduced by the classical reciprocal-interaction model. Using mathematical formalisms developed in the field of computational neuroscience to model neuronal population activity, these models investigate the dynamics of proposed conceptual models of sleep-wake regulatory networks with a focus on generating appropriate sleep and wake state transition patterns as well as simulating disease states and experimental protocols. In this review, we discuss several recent physiologically-based mathematical models of sleep-wake regulatory networks. We identify common features among these models in their network structures, model dynamics and approaches for model validation. We describe how the model analysis technique of fast-slow decomposition, which exploits the naturally occurring multiple timescales of sleep-wake behavior, can be applied to understand model dynamics in these networks. Our purpose in identifying commonalities among these models is to propel understanding of both the mathematical models and their underlying conceptual models, and focus directions for future experimental and theoretical work.
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11
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Resch JM, Maunze B, Gerhardt AK, Magnuson SK, Phillips KA, Choi S. Intrahypothalamic pituitary adenylate cyclase-activating polypeptide regulates energy balance via site-specific actions on feeding and metabolism. Am J Physiol Endocrinol Metab 2013; 305:E1452-63. [PMID: 24148346 PMCID: PMC3882380 DOI: 10.1152/ajpendo.00293.2013] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Numerous studies have demonstrated that both the hypothalamic paraventricular nuclei (PVN) and ventromedial nuclei (VMN) regulate energy homeostasis through behavioral and metabolic mechanisms. Receptors for pituitary adenylate cyclase-activating polypeptide (PACAP) are abundantly expressed in these nuclei, suggesting PACAP may be critical for the regulation of feeding behavior and body weight. To characterize the unique behavioral and physiological responses attributed to select hypothalamic cell groups, PACAP was site-specifically injected into the PVN or VMN. Overall food intake was significantly reduced by PACAP at both sites; however, meal pattern analysis revealed that only injections into the PVN produced significant reductions in meal size, duration, and total time spent eating. PACAP-mediated hypophagia in both the PVN and VMN was abolished by PAC1R antagonism, whereas pretreatment with a VPACR antagonist had no effect. PACAP injections into the VMN produced unique changes in metabolic parameters, including significant increases in core body temperature and spontaneous locomotor activity that was PAC1R dependent whereas, PVN injections of PACAP had no effect. Finally, PACAP-containing afferents were identified using the neuronal tracer cholera toxin subunit B (CTB) injected unilaterally into the PVN or VMN. CTB signal from PVN injections was colocalized with PACAP mRNA in the medial anterior bed nucleus of the stria terminalis, VMN, and lateral parabrachial nucleus (LPB), whereas CTB signal from VMN injections was highly colocalized with PACAP mRNA in the medial amygdala and LPB. These brain regions are known to influence energy homeostasis perhaps, in part, through PACAP projections to the PVN and VMN.
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Affiliation(s)
- Jon M Resch
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin
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12
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Kudo T, Tahara Y, Gamble KL, McMahon DG, Block GD, Colwell CS. Vasoactive intestinal peptide produces long-lasting changes in neural activity in the suprachiasmatic nucleus. J Neurophysiol 2013; 110:1097-106. [PMID: 23741043 DOI: 10.1152/jn.00114.2013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The neuropeptide vasoactive intestinal peptide (VIP) is expressed at high levels in the neurons of the suprachiasmatic nucleus (SCN). While VIP is known to be important to the input and output pathways from the SCN, the physiological effects of VIP on electrical activity of SCN neurons are not well known. Here the impact of VIP on firing rate of SCN neurons was investigated in mouse slice cultures recorded during the night. The application of VIP produced an increase in electrical activity in SCN slices that lasted several hours after treatment. This is a novel mechanism by which this peptide can produce long-term changes in central nervous system physiology. The increase in action potential frequency was blocked by a VIP receptor antagonist and lost in a VIP receptor knockout mouse. In addition, inhibitors of both the Epac family of cAMP binding proteins and cAMP-dependent protein kinase (PKA) blocked the induction by VIP. The persistent increase in spike rate following VIP application was not seen in SCN neurons from mice deficient in Kv3 channel proteins and was dependent on the clock protein PER1. These findings suggest that VIP regulates the long-term firing rate of SCN neurons through a VIPR2-mediated increase in the cAMP pathway and implicate the fast delayed rectifier (FDR) potassium currents as one of the targets of this regulation.
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Affiliation(s)
- Takashi Kudo
- Laboratory of Circadian and Sleep Medicine, Department of Psychiatry and Biobehavioral Sciences, University of California-Los Angeles, CA 90024, USA
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13
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Bechtold DA, Loudon AS. Hypothalamic clocks and rhythms in feeding behaviour. Trends Neurosci 2013; 36:74-82. [DOI: 10.1016/j.tins.2012.12.007] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 12/16/2012] [Indexed: 01/23/2023]
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14
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Hermes MLHJ, Kolaj M, Coderre EM, Renaud LP. Gastrin-releasing peptide acts via postsynaptic BB2 receptors to modulate inward rectifier K+ and TRPV1-like conductances in rat paraventricular thalamic neurons. J Physiol 2013; 591:1823-39. [PMID: 23359674 DOI: 10.1113/jphysiol.2012.249227] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Gastrin-releasing peptide (GRP) is a bombesin-like peptide with a widespread distribution in mammalian CNS, where it has a role in food intake, circadian rhythm generation, fear memory, itch sensation and sexual behaviour. While it has been established that GRP predominantly excites neurons, details of the membrane mechanism involved in this action remain largely undefined. We used perforated patch clamp recording in acute brain slice preparations to investigate GRP-affected receptors and ionic conductances in neurons of the rat paraventricular thalamic nucleus (PVT). PVT is a component of the midline and intralaminar thalamus that participates in arousal, motivational drives and stress responses, and exhibits a prominence of GRP-like immunoreactive fibres. Exposure of PVT neurons to low nanomolar concentrations of GRP induced sustained TTX-resistant membrane depolarizations that could trigger rhythmic burst discharges or tonic firing. Membrane current analyses in voltage clamp revealed an underlying postsynaptic bombesin type 2 receptor-mediated inward current that resulted from the simultaneous suppression of a Ba(2+)-sensitive inward rectifier K(+) conductance and activation of a non-selective cation conductance with biophysical and pharmacological properties reminiscent of transient receptor potential vanilloid (TRPV) 1. A role for a TRPV1-like conductance was further implied by a significant suppressant influence of a TRPV1 antagonist on GRP-induced membrane depolarization and rhythmic burst or tonic firing. The results provide a detailed picture of the receptor and ionic conductances that are involved in GRP's excitatory action in midline thalamus.
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Affiliation(s)
- M L H J Hermes
- Neuroscience Program, Ottawa Hospital Research Institute and Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada K1Y 4E9.
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15
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Todd WD, Gall AJ, Weiner JA, Blumberg MS. Distinct retinohypothalamic innervation patterns predict the developmental emergence of species-typical circadian phase preference in nocturnal Norway rats and diurnal nile grass rats. J Comp Neurol 2012; 520:3277-92. [PMID: 22431036 PMCID: PMC3676184 DOI: 10.1002/cne.23098] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
How does the brain develop differently to support nocturnality in some mammals, but diurnality in others? To answer this question, one might look to the suprachiasmatic nucleus (SCN), which is entrained by light via the retinohypothalamic tract (RHT). However, because the SCN is more active during the day in all mammals studied thus far, it alone cannot determine circadian phase preference. In adult Norway rats (Rattus norvegicus), which are nocturnal, the RHT also projects to the ventral subparaventricular zone (vSPVZ), an adjacent region that expresses an in-phase pattern of SCN-vSPVZ neuronal activity. In contrast, in adult Nile grass rats (Arvicanthis niloticus), which are diurnal, an anti-phase pattern of SCN-vSPVZ neuronal activity is expressed. We hypothesized that these species differences result in part from a weak or absent RHT-to-vSPVZ projection in grass rats. Here, using a developmental comparative approach, we assessed species differences in behavior, hypothalamic activity, and RHT anatomy. We report that a robust retina-to-vSPVZ projection develops in Norway rats around the end of the second postnatal week when nocturnal wakefulness and the in-phase pattern of neuronal activity emerge. In grass rats, however, such a projection does not develop and the emergence of the anti-phase pattern during the second postnatal week is accompanied by increased diurnal wakefulness. When considered within the context of previously published reports on RHT projections in a variety of species, the current findings suggest that how and when the retina connects to the hypothalamus differentially shapes brain and behavior to produce animals that occupy opposing temporal niches.
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Affiliation(s)
- William D. Todd
- Program in Behavioral and Cognitive Neuroscience, Department of Psychology, University of Iowa, Iowa City, IA, 52242, USA
| | - Andrew J. Gall
- Program in Behavioral and Cognitive Neuroscience, Department of Psychology, University of Iowa, Iowa City, IA, 52242, USA
| | - Joshua A. Weiner
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA
| | - Mark S. Blumberg
- Program in Behavioral and Cognitive Neuroscience, Department of Psychology, University of Iowa, Iowa City, IA, 52242, USA
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Fleshner M, Booth V, Forger DB, Diniz Behn CG. Circadian regulation of sleep-wake behaviour in nocturnal rats requires multiple signals from suprachiasmatic nucleus. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:3855-83. [PMID: 21893532 DOI: 10.1098/rsta.2011.0085] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The dynamics of sleep and wake are strongly linked to the circadian clock. Many models have accurately predicted behaviour resulting from dynamic interactions between these two systems without specifying physiological substrates for these interactions. By contrast, recent experimental work has identified much of the relevant physiology for circadian and sleep-wake regulation, but interaction dynamics are difficult to study experimentally. To bridge these approaches, we developed a neuronal population model for the dynamic, bidirectional, neurotransmitter-mediated interactions of the sleep-wake and circadian regulatory systems in nocturnal rats. This model proposes that the central circadian pacemaker, located within the suprachiasmatic nucleus (SCN) of the hypothalamus, promotes sleep through single neurotransmitter-mediated signalling to sleep-wake regulatory populations. Feedback projections from these populations to the SCN alter SCN firing patterns and fine-tune this modulation. Although this model reproduced circadian variation in sleep-wake dynamics in nocturnal rats, it failed to describe the sleep-wake dynamics observed in SCN-lesioned rats. We thus propose two alternative, physiologically based models in which neurotransmitter- and neuropeptide-mediated signalling from the SCN to sleep-wake populations introduces mechanisms to account for the behaviour of both the intact and SCN-lesioned rat. These models generate testable predictions and offer a new framework for modelling sleep-wake and circadian interactions.
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Affiliation(s)
- Michelle Fleshner
- Department of Mathematics, University of Michigan, 530 Church Street, Ann Arbor, MI 48109-1043, USA
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17
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Loh DH, Dragich JM, Kudo T, Schroeder AM, Nakamura TJ, Waschek JA, Block GD, Colwell CS. Effects of vasoactive intestinal peptide genotype on circadian gene expression in the suprachiasmatic nucleus and peripheral organs. J Biol Rhythms 2011; 26:200-9. [PMID: 21628547 PMCID: PMC3942163 DOI: 10.1177/0748730411401740] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The neuropeptide vasoactive intestinal polypeptide (VIP) has emerged as a key candidate molecule mediating the synchronization of rhythms in clock gene expression within the suprachiasmatic nucleus (SCN). In addition, neurons expressing VIP are anatomically well positioned to mediate communication between the SCN and peripheral oscillators. In this study, we examined the temporal expression profile of 3 key circadian genes: Per1, Per2 , and Bmal1 in the SCN, the adrenal glands and the liver of mice deficient for the Vip gene (VIP KO), and their wild-type counterparts. We performed these measurements in mice held in a light/dark cycle as well as in constant darkness and found that rhythms in gene expression were greatly attenuated in the VIP-deficient SCN. In the periphery, the impact of the loss of VIP varied with the tissue and gene measured. In the adrenals, rhythms in Per1 were lost in VIP-deficient mice, while in the liver, the most dramatic impact was on the phase of the diurnal expression rhythms. Finally, we examined the effects of the loss of VIP on ex vivo explants of the same central and peripheral oscillators using the PER2::LUC reporter system. The VIP-deficient mice exhibited low amplitude rhythms in the SCN as well as altered phase relationships between the SCN and the peripheral oscillators. Together, these data suggest that VIP is critical for robust rhythms in clock gene expression in the SCN and some peripheral organs and that the absence of this peptide alters both the amplitude of circadian rhythms as well as the phase relationships between the rhythms in the SCN and periphery.
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Affiliation(s)
- Dawn H. Loh
- Department of Psychiatry and Biobehavioral Sciences, University of California–Los Angeles, Los Angeles, CA
| | - Joanna M. Dragich
- Department of Psychiatry and Biobehavioral Sciences, University of California–Los Angeles, Los Angeles, CA
| | - Takashi Kudo
- Department of Psychiatry and Biobehavioral Sciences, University of California–Los Angeles, Los Angeles, CA
| | - Analyne M. Schroeder
- Department of Psychiatry and Biobehavioral Sciences, University of California–Los Angeles, Los Angeles, CA
| | - Takahiro J. Nakamura
- Department of Psychiatry and Biobehavioral Sciences, University of California–Los Angeles, Los Angeles, CA
| | - James A. Waschek
- Department of Psychiatry and Biobehavioral Sciences, University of California–Los Angeles, Los Angeles, CA
| | - Gene D. Block
- Department of Psychiatry and Biobehavioral Sciences, University of California–Los Angeles, Los Angeles, CA
| | - Christopher S. Colwell
- Department of Psychiatry and Biobehavioral Sciences, University of California–Los Angeles, Los Angeles, CA
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18
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Abstract
Neuroactive peptides and the intracellular calcium concentration ([Ca(2+) ](i) ) play important roles in light-induced modulation of gene expression in the suprachiasmatic nucleus (SCN) neurons that ultimately control behavioral rhythms. Vasoactive intestinal peptide (VIP) and arginine vasopressin (AVP) are expressed rhythmically within populations of SCN neurons. Pituitary adenylate cyclase-activating peptide (PACAP) is released from retinohypothalamic tract (RHT) terminals synapsing on SCN neurons. Nociceptin/orphanin FQ (OFQ) receptors are functionally expressed in the SCN. We examined the role of several neuropeptides on Ca(2+) signaling, simultaneously imaging multiple neurons within the SCN neural network. VIP reduced the [Ca(2+) ](i) in populations of SCN neurons during the day, but had little effect at night. Stimulation of the RHT at frequencies that simulate light input signaling evoked transient [Ca(2+) ](i) elevations that were not altered by VIP. AVP elevated the [Ca(2+) ](i) during both the day and night, PACAP produced variable responses, and OFQ induced a reduction in the [Ca(2+) ](i) similar to VIP. During the day, VIP lowered the [Ca(2+) ](i) to near nighttime levels, while AVP elevated [Ca(2+) ](i) during both the day and night, suggesting that the VIP effects on [Ca(2+) ](i) were dependent, and the AVP effects independent of the action potential firing activity state of the neuron. We hypothesize that VIP and AVP regulate, at least in part, Ca(2+) homeostasis in SCN neurons and may be a major point of regulation for SCN neuronal synchronization.
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Affiliation(s)
- Robert P Irwin
- Center for Research on Occupational and Environmental Toxicology (CROET), Oregon Health & Science University, L-606, Portland, OR, 97239 USA.
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Pantazopoulos H, Dolatshad H, Davis FC. Chronic stimulation of the hypothalamic vasoactive intestinal peptide receptor lengthens circadian period in mice and hamsters. Am J Physiol Regul Integr Comp Physiol 2010; 299:R379-85. [PMID: 20463182 DOI: 10.1152/ajpregu.00176.2010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Evidence suggests that circadian rhythms are regulated through diffusible signals generated by the suprachiasmatic nucleus (SCN). Vasoactive intestinal peptide (VIP) is located in SCN neurons positioned to receive photic input from the retinohypothalamic tract and transmit information to other SCN cells and adjacent hypothalamic areas. Studies using knockout mice indicate that VIP is essential for synchrony among SCN cells and for the expression of normal circadian rhythms. To test the hypothesis that VIP is also an SCN output signal, we recorded wheel-running activity rhythms in hamsters and continuously infused the VIP receptor agonist BAY 55-9837 in the third ventricle for 28 days. Unlike other candidate output signals, infusion of BAY 55-9837 did not affect activity levels. Instead, BAY 55-9837 lengthened the circadian period by 0.69 +/- 0.04 h (P < 0.0002 compared with controls). Period returned to baseline after infusions. We analyzed the effect of BAY 55-9837 on cultured SCN from PER2::LUC mice to determine if lengthening of the period by BAY 55-9837 is a direct effect on the SCN. Application of 10 muM BAY 55-9837 to SCN in culture lengthened the period of PER2 luciferase expression (24.73 +/- 0.24 h) compared with control SCN (23.57 +/- 0.26, P = 0.01). In addition, rhythm amplitude was significantly increased, consistent with increased synchronization of SCN neurons. The effect of BAY 55-9837 in vivo on period is similar to the effect of constant light. The present results suggest that VIP-VPAC2 signaling in the SCN may play two roles, synchronizing SCN neurons and setting the period of the SCN as a whole.
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Affiliation(s)
- Harry Pantazopoulos
- Department of Biology, Northeastern University, Boston, Massachusetts 02478, USA
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