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Eckstein N, Bates AS, Champion A, Du M, Yin Y, Schlegel P, Lu AKY, Rymer T, Finley-May S, Paterson T, Parekh R, Dorkenwald S, Matsliah A, Yu SC, McKellar C, Sterling A, Eichler K, Costa M, Seung S, Murthy M, Hartenstein V, Jefferis GSXE, Funke J. Neurotransmitter classification from electron microscopy images at synaptic sites in Drosophila melanogaster. Cell 2024; 187:2574-2594.e23. [PMID: 38729112 PMCID: PMC11106717 DOI: 10.1016/j.cell.2024.03.016] [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] [Received: 04/02/2023] [Revised: 10/04/2023] [Accepted: 03/13/2024] [Indexed: 05/12/2024]
Abstract
High-resolution electron microscopy of nervous systems has enabled the reconstruction of synaptic connectomes. However, we do not know the synaptic sign for each connection (i.e., whether a connection is excitatory or inhibitory), which is implied by the released transmitter. We demonstrate that artificial neural networks can predict transmitter types for presynapses from electron micrographs: a network trained to predict six transmitters (acetylcholine, glutamate, GABA, serotonin, dopamine, octopamine) achieves an accuracy of 87% for individual synapses, 94% for neurons, and 91% for known cell types across a D. melanogaster whole brain. We visualize the ultrastructural features used for prediction, discovering subtle but significant differences between transmitter phenotypes. We also analyze transmitter distributions across the brain and find that neurons that develop together largely express only one fast-acting transmitter (acetylcholine, glutamate, or GABA). We hope that our publicly available predictions act as an accelerant for neuroscientific hypothesis generation for the fly.
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Affiliation(s)
- Nils Eckstein
- HHMI Janelia Research Campus, Ashburn, VA, USA; Institute of Neuroinformatics UZH/ETHZ, Zurich, Switzerland
| | - Alexander Shakeel Bates
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK; Centre for Neural Circuits and Behaviour, The University of Oxford, Tinsley Building, Mansfield Road, Oxford OX1 3SR, UK; Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Andrew Champion
- Drosophila Connectomics Group, Department of Zoology, University of Cambridge, Cambridge, UK
| | - Michelle Du
- HHMI Janelia Research Campus, Ashburn, VA, USA
| | - Yijie Yin
- Drosophila Connectomics Group, Department of Zoology, University of Cambridge, Cambridge, UK
| | - Philipp Schlegel
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK; Drosophila Connectomics Group, Department of Zoology, University of Cambridge, Cambridge, UK
| | | | | | | | | | | | - Sven Dorkenwald
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA
| | - Arie Matsliah
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA
| | - Szi-Chieh Yu
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA
| | - Claire McKellar
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA
| | - Amy Sterling
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA
| | - Katharina Eichler
- Drosophila Connectomics Group, Department of Zoology, University of Cambridge, Cambridge, UK
| | - Marta Costa
- Drosophila Connectomics Group, Department of Zoology, University of Cambridge, Cambridge, UK
| | - Sebastian Seung
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA
| | - Mala Murthy
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA
| | - Volker Hartenstein
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Gregory S X E Jefferis
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK; Drosophila Connectomics Group, Department of Zoology, University of Cambridge, Cambridge, UK.
| | - Jan Funke
- HHMI Janelia Research Campus, Ashburn, VA, USA.
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Jagannathan SR, Jeans T, Van De Poll MN, van Swinderen B. Multivariate classification of multichannel long-term electrophysiology data identifies different sleep stages in fruit flies. SCIENCE ADVANCES 2024; 10:eadj4399. [PMID: 38381836 PMCID: PMC10881036 DOI: 10.1126/sciadv.adj4399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 01/18/2024] [Indexed: 02/23/2024]
Abstract
Identifying different sleep stages in humans and other mammals has traditionally relied on electroencephalograms. Such an approach is not feasible in certain animals such as invertebrates, although these animals could also be sleeping in stages. Here, we perform long-term multichannel local field potential recordings in the brains of behaving flies undergoing spontaneous sleep bouts. We acquired consistent spatial recordings of local field potentials across multiple flies, allowing us to compare brain activity across awake and sleep periods. Using machine learning, we uncover distinct temporal stages of sleep and explore the associated spatial and spectral features across the fly brain. Further, we analyze the electrophysiological correlates of microbehaviors associated with certain sleep stages. We confirm the existence of a distinct sleep stage associated with rhythmic proboscis extensions and show that spectral features of this sleep-related behavior differ significantly from those associated with the same behavior during wakefulness, indicating a dissociation between behavior and the brain states wherein these behaviors reside.
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Affiliation(s)
- Sridhar R. Jagannathan
- Department of Psychology, University of Cambridge, Cambridge, UK
- Institute of Neurophysiology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Travis Jeans
- Queensland Brain Institute, The University of Queensland, St Lucia, QLD Australia
| | | | - Bruno van Swinderen
- Queensland Brain Institute, The University of Queensland, St Lucia, QLD Australia
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3
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Anthoney N, Tainton-Heap L, Luong H, Notaras E, Kewin AB, Zhao Q, Perry T, Batterham P, Shaw PJ, van Swinderen B. Experimentally induced active and quiet sleep engage non-overlapping transcriptional programs in Drosophila. eLife 2023; 12:RP88198. [PMID: 37910019 PMCID: PMC10619980 DOI: 10.7554/elife.88198] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2023] Open
Abstract
Sleep in mammals can be broadly classified into two different physiological categories: rapid eye movement (REM) sleep and slow-wave sleep (SWS), and accordingly REM and SWS are thought to achieve a different set of functions. The fruit fly Drosophila melanogaster is increasingly being used as a model to understand sleep functions, although it remains unclear if the fly brain also engages in different kinds of sleep as well. Here, we compare two commonly used approaches for studying sleep experimentally in Drosophila: optogenetic activation of sleep-promoting neurons and provision of a sleep-promoting drug, gaboxadol. We find that these different sleep-induction methods have similar effects on increasing sleep duration, but divergent effects on brain activity. Transcriptomic analysis reveals that drug-induced deep sleep ('quiet' sleep) mostly downregulates metabolism genes, whereas optogenetic 'active' sleep upregulates a wide range of genes relevant to normal waking functions. This suggests that optogenetics and pharmacological induction of sleep in Drosophila promote different features of sleep, which engage different sets of genes to achieve their respective functions.
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Affiliation(s)
- Niki Anthoney
- Queensland Brain Institute, The University of QueenslandBrisbaneAustralia
| | - Lucy Tainton-Heap
- Queensland Brain Institute, The University of QueenslandBrisbaneAustralia
| | - Hang Luong
- School of BioSciences, The University of MelbourneMelbourneAustralia
| | - Eleni Notaras
- Queensland Brain Institute, The University of QueenslandBrisbaneAustralia
| | - Amber B Kewin
- Queensland Brain Institute, The University of QueenslandBrisbaneAustralia
| | - Qiongyi Zhao
- Queensland Brain Institute, The University of QueenslandBrisbaneAustralia
| | - Trent Perry
- School of BioSciences, The University of MelbourneMelbourneAustralia
| | - Philip Batterham
- School of BioSciences, The University of MelbourneMelbourneAustralia
| | - Paul J Shaw
- Department of Neuroscience, School of Medicine, Washington University in St. LouisSt LouisUnited States
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4
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Anthoney N, Tainton-Heap LA, Luong H, Notaras E, Kewin AB, Zhao Q, Perry T, Batterham P, Shaw PJ, van Swinderen B. Experimentally induced active and quiet sleep engage non-overlapping transcriptional programs in Drosophila. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.03.535331. [PMID: 37066182 PMCID: PMC10103959 DOI: 10.1101/2023.04.03.535331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Sleep in mammals can be broadly classified into two different physiological categories: rapid eye movement (REM) sleep and slow wave sleep (SWS), and accordingly REM and SWS are thought to achieve a different set of functions. The fruit fly Drosophila melanogaster is increasingly being used as a model to understand sleep functions, although it remains unclear if the fly brain also engages in different kinds of sleep as well. Here, we compare two commonly used approaches for studying sleep experimentally in Drosophila: optogenetic activation of sleep-promoting neurons and provision of a sleep-promoting drug, Gaboxadol. We find that these different sleep-induction methods have similar effects on increasing sleep duration, but divergent effects on brain activity. Transcriptomic analysis reveals that drug-induced deep sleep ('quiet' sleep) mostly downregulates metabolism genes, whereas optogenetic 'active' sleep upregulates a wide range of genes relevant to normal waking functions. This suggests that optogenetics and pharmacological induction of sleep in Drosophila promote different features of sleep, which engage different sets of genes to achieve their respective functions.
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Affiliation(s)
- Niki Anthoney
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072 Australia
| | | | - Hang Luong
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3052 Australia
| | - Eleni Notaras
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Amber B. Kewin
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Qiongyi Zhao
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Trent Perry
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3052 Australia
| | - Philip Batterham
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3052 Australia
| | - Paul J. Shaw
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO USA
| | - Bruno van Swinderen
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072 Australia
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5
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De J, Wu M, Lambatan V, Hua Y, Joiner WJ. Re-examining the role of the dorsal fan-shaped body in promoting sleep in Drosophila. Curr Biol 2023; 33:3660-3668.e4. [PMID: 37552985 PMCID: PMC10573663 DOI: 10.1016/j.cub.2023.07.043] [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] [Received: 03/02/2023] [Revised: 06/10/2023] [Accepted: 07/20/2023] [Indexed: 08/10/2023]
Abstract
The needs fulfilled by sleep are unknown, though the effects of insufficient sleep are manifold. To better understand how the need to sleep is sensed and discharged, much effort has gone into identifying the neural circuits involved in regulating arousal, especially those that promote sleep. In prevailing models, the dorsal fan-shaped body (dFB) plays a central role in this process in the fly brain. In the present study we manipulated various properties of the dFB including its electrical activity, synaptic output, and endogenous gene expression. In each of these experimental contexts we were unable to identify any effect on sleep that could be unambiguously mapped to the dFB. Furthermore, we found evidence that sleep phenotypes previously attributed to the dFB were caused by genetic manipulations that inadvertently targeted the ventral nerve cord. We also examined expression of two genes whose purported effects have been attributed to functions within a specific subpopulation of dFB neurons. In both cases we found little to no expression in the expected cells. Collectively, our results cast doubt on the prevailing hypothesis that the dFB plays a central role in promoting sleep.
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Affiliation(s)
- Joydeep De
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Meilin Wu
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Vanessa Lambatan
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yue Hua
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - William J Joiner
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA; Center for Circadian Biology, University of California, San Diego, La Jolla, CA 92093, USA.
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6
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Troup M, Tainton-Heap LAL, van Swinderen B. Neural Ensemble Fragmentation in the Anesthetized Drosophila Brain. J Neurosci 2023; 43:2537-2551. [PMID: 36868857 PMCID: PMC10082453 DOI: 10.1523/jneurosci.1657-22.2023] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 02/15/2023] [Accepted: 02/22/2023] [Indexed: 03/05/2023] Open
Abstract
General anesthetics cause a profound loss of behavioral responsiveness in all animals. In mammals, general anesthesia is induced in part by the potentiation of endogenous sleep-promoting circuits, although "deep" anesthesia is understood to be more similar to coma (Brown et al., 2011). Surgically relevant concentrations of anesthetics, such as isoflurane and propofol, have been shown to impair neural connectivity across the mammalian brain (Mashour and Hudetz, 2017; Yang et al., 2021), which presents one explanation why animals become largely unresponsive when exposed to these drugs. It remains unclear whether general anesthetics affect brain dynamics similarly in all animal brains, or whether simpler animals, such as insects, even display levels of neural connectivity that could be disrupted by these drugs. Here, we used whole-brain calcium imaging in behaving female Drosophila flies to investigate whether isoflurane anesthesia induction activates sleep-promoting neurons, and then inquired how all other neurons across the fly brain behave under sustained anesthesia. We were able to track the activity of hundreds of neurons simultaneously during waking and anesthetized states, for spontaneous conditions as well as in response to visual and mechanical stimuli. We compared whole-brain dynamics and connectivity under isoflurane exposure to optogenetically induced sleep. Neurons in the Drosophila brain remain active during general anesthesia as well as induced sleep, although flies become behaviorally inert under both treatments. We identified surprisingly dynamic neural correlation patterns in the waking fly brain, suggesting ensemble-like behavior. These become more fragmented and less diverse under anesthesia but remain wake-like during induced sleep.SIGNIFICANCE STATEMENT When humans are rendered immobile and unresponsive by sleep or general anesthetics, their brains do not shut off - they just change how they operate. We tracked the activity of hundreds of neurons simultaneously in the brains of fruit flies that were anesthetized by isoflurane or genetically put to sleep, to investigate whether these behaviorally inert states shared similar brain dynamics. We uncovered dynamic patterns of neural activity in the waking fly brain, with stimulus-responsive neurons constantly changing through time. Wake-like neural dynamics persisted during induced sleep but became more fragmented under isoflurane anesthesia. This suggests that, like larger brains, the fly brain might also display ensemble-like behavior, which becomes degraded rather than silenced under general anesthesia.
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Affiliation(s)
- Michael Troup
- Queensland Brain Institute, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Lucy A L Tainton-Heap
- Queensland Brain Institute, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Bruno van Swinderen
- Queensland Brain Institute, The University of Queensland, St. Lucia, Queensland 4072, Australia
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7
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Titos I, Juginović A, Vaccaro A, Nambara K, Gorelik P, Mazor O, Rogulja D. A gut-secreted peptide suppresses arousability from sleep. Cell 2023; 186:1382-1397.e21. [PMID: 36958331 PMCID: PMC10216829 DOI: 10.1016/j.cell.2023.02.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 08/26/2022] [Accepted: 02/16/2023] [Indexed: 03/25/2023]
Abstract
Suppressing sensory arousal is critical for sleep, with deeper sleep requiring stronger sensory suppression. The mechanisms that enable sleeping animals to largely ignore their surroundings are not well understood. We show that the responsiveness of sleeping flies and mice to mechanical vibrations is better suppressed when the diet is protein rich. In flies, we describe a signaling pathway through which information about ingested proteins is conveyed from the gut to the brain to help suppress arousability. Higher protein concentration in the gut leads to increased activity of enteroendocrine cells that release the peptide CCHa1. CCHa1 signals to a small group of dopamine neurons in the brain to modulate their activity; the dopaminergic activity regulates the behavioral responsiveness of animals to vibrations. The CCHa1 pathway and dietary proteins do not influence responsiveness to all sensory inputs, showing that during sleep, different information streams can be gated through independent mechanisms.
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Affiliation(s)
- Iris Titos
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Alen Juginović
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Alexandra Vaccaro
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Keishi Nambara
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Pavel Gorelik
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Ofer Mazor
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Dragana Rogulja
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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8
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Dissel S, Klose MK, van Swinderen B, Cao L, Ford M, Periandri EM, Jones JD, Li Z, Shaw PJ. Sleep-promoting neurons remodel their response properties to calibrate sleep drive with environmental demands. PLoS Biol 2022; 20:e3001797. [PMID: 36173939 PMCID: PMC9521806 DOI: 10.1371/journal.pbio.3001797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 08/16/2022] [Indexed: 01/29/2023] Open
Abstract
Falling asleep at the wrong time can place an individual at risk of immediate physical harm. However, not sleeping degrades cognition and adaptive behavior. To understand how animals match sleep need with environmental demands, we used live-brain imaging to examine the physiological response properties of the dorsal fan-shaped body (dFB) following interventions that modify sleep (sleep deprivation, starvation, time-restricted feeding, memory consolidation) in Drosophila. We report that dFB neurons change their physiological response-properties to dopamine (DA) and allatostatin-A (AstA) in response to different types of waking. That is, dFB neurons are not simply passive components of a hard-wired circuit. Rather, the dFB neurons intrinsically regulate their response to the activity from upstream circuits. Finally, we show that the dFB appears to contain a memory trace of prior exposure to metabolic challenges induced by starvation or time-restricted feeding. Together, these data highlight that the sleep homeostat is plastic and suggests an underlying mechanism.
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Affiliation(s)
- Stephane Dissel
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, Missouri, United States of America
- * E-mail: (SD); (PJS)
| | - Markus K. Klose
- University of Pittsburgh School of Medicine, Department of Pharmacology & Chemical Biology, Pittsburgh, Pennsylvania, United States of America
| | - Bruno van Swinderen
- Queensland Brain Institute, The University of Queensland, St Lucia, Australia
| | - Lijuan Cao
- Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Melanie Ford
- Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Erica M. Periandri
- Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Joseph D. Jones
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, Missouri, United States of America
| | - Zhaoyi Li
- Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Paul J. Shaw
- Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail: (SD); (PJS)
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9
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Gong NN, Luong HNB, Dang AH, Mainwaring B, Shields E, Schmeckpeper K, Bonasio R, Kayser MS. Intrinsic maturation of sleep output neurons regulates sleep ontogeny in Drosophila. Curr Biol 2022; 32:4025-4039.e3. [PMID: 35985328 PMCID: PMC9529826 DOI: 10.1016/j.cub.2022.07.054] [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] [Received: 11/04/2021] [Revised: 06/06/2022] [Accepted: 07/21/2022] [Indexed: 11/19/2022]
Abstract
The maturation of sleep behavior across a lifespan (sleep ontogeny) is an evolutionarily conserved phenomenon. Mammalian studies have shown that in addition to increased sleep duration, early life sleep exhibits stark differences compared with mature sleep with regard to sleep states. How the intrinsic maturation of sleep output circuits contributes to sleep ontogeny is poorly understood. The fruit fly Drosophila melanogaster exhibits multifaceted changes to sleep from juvenile to mature adulthood. Here, we use a non-invasive probabilistic approach to investigate the changes in sleep architecture in juvenile and mature flies. Increased sleep in juvenile flies is driven primarily by a decreased probability of transitioning to wake and characterized by more time in deeper sleep states. Functional manipulations of sleep-promoting neurons in the dorsal fan-shaped body (dFB) suggest that these neurons differentially regulate sleep in juvenile and mature flies. Transcriptomic analysis of dFB neurons at different ages and a subsequent RNAi screen implicate the genes involved in dFB sleep circuit maturation. These results reveal that the dynamic transcriptional states of sleep output neurons contribute to the changes in sleep across the lifespan.
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Affiliation(s)
- Naihua N Gong
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Hang Ngoc Bao Luong
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - An H Dang
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Benjamin Mainwaring
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Emily Shields
- Department of Urology and Institute of Neuropathology, Medical Center-University of Freiburg, 79106 Freiburg, Germany; Epigenetics Institute and Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Karl Schmeckpeper
- Department of Computer Science, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Roberto Bonasio
- Epigenetics Institute and Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Matthew S Kayser
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Chronobiology and Sleep Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA.
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10
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Zlomuzica A, Plank L, Dere E. A new path to mental disorders: Through gap junction channels and hemichannels. Neurosci Biobehav Rev 2022; 142:104877. [PMID: 36116574 DOI: 10.1016/j.neubiorev.2022.104877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 08/20/2022] [Accepted: 09/13/2022] [Indexed: 11/18/2022]
Abstract
Behavioral disturbances related to emotional regulation, reward processing, cognition, sleep-wake regulation and activity/movement represent core symptoms of most common mental disorders. Increasing empirical and theoretical evidence suggests that normal functioning of these behavioral domains relies on fine graded coordination of neural and glial networks which are maintained and modulated by intercellular gap junction channels and unapposed pannexin or connexin hemichannels. Dysfunctions in these networks might contribute to the development and maintenance of psychopathological and neurobiological features associated with mental disorders. Here we review and discuss the evidence indicating a prominent role of gap junction channel and hemichannel dysfunction in core symptoms of mental disorders. We further discuss how the increasing knowledge on intercellular gap junction channels and unapposed pannexin or connexin hemichannels in the brain might lead to deeper mechanistic insight in common mental disorders and to the development of novel treatment approaches. We further attempt to exemplify what type of future research on this topic could be integrated into multidimensional approaches to understand and cure mental disorders.
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Affiliation(s)
- Armin Zlomuzica
- Department of Behavioral and Clinical Neuroscience, Ruhr-University Bochum (RUB), Massenbergstraße 9-13, D-44787 Bochum, Germany.
| | - Laurin Plank
- Department of Behavioral and Clinical Neuroscience, Ruhr-University Bochum (RUB), Massenbergstraße 9-13, D-44787 Bochum, Germany
| | - Ekrem Dere
- Department of Behavioral and Clinical Neuroscience, Ruhr-University Bochum (RUB), Massenbergstraße 9-13, D-44787 Bochum, Germany; Sorbonne Université. Institut de Biologie Paris-Seine, (IBPS), Département UMR 8256: Adaptation Biologique et Vieillissement, UFR des Sciences de la Vie, Campus Pierre et Marie Curie, Bâtiment B, 9 quai Saint Bernard, F-75005 Paris, France.
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11
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Ammer G, Vieira RM, Fendl S, Borst A. Anatomical distribution and functional roles of electrical synapses in Drosophila. Curr Biol 2022; 32:2022-2036.e4. [DOI: 10.1016/j.cub.2022.03.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 02/16/2022] [Accepted: 03/14/2022] [Indexed: 10/18/2022]
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12
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Van De Poll MN, van Swinderen B. Balancing Prediction and Surprise: A Role for Active Sleep at the Dawn of Consciousness? Front Syst Neurosci 2021; 15:768762. [PMID: 34803618 PMCID: PMC8602873 DOI: 10.3389/fnsys.2021.768762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 10/08/2021] [Indexed: 11/14/2022] Open
Abstract
The brain is a prediction machine. Yet the world is never entirely predictable, for any animal. Unexpected events are surprising, and this typically evokes prediction error signatures in mammalian brains. In humans such mismatched expectations are often associated with an emotional response as well, and emotional dysregulation can lead to cognitive disorders such as depression or schizophrenia. Emotional responses are understood to be important for memory consolidation, suggesting that positive or negative 'valence' cues more generally constitute an ancient mechanism designed to potently refine and generalize internal models of the world and thereby minimize prediction errors. On the other hand, abolishing error detection and surprise entirely (as could happen by generalization or habituation) is probably maladaptive, as this might undermine the very mechanism that brains use to become better prediction machines. This paradoxical view of brain function as an ongoing balance between prediction and surprise suggests a compelling approach to study and understand the evolution of consciousness in animals. In particular, this view may provide insight into the function and evolution of 'active' sleep. Here, we propose that active sleep - when animals are behaviorally asleep but their brain seems awake - is widespread beyond mammals and birds, and may have evolved as a mechanism for optimizing predictive processing in motile creatures confronted with constantly changing environments. To explore our hypothesis, we progress from humans to invertebrates, investigating how a potential role for rapid eye movement (REM) sleep in emotional regulation in humans could be re-examined as a conserved sleep function that co-evolved alongside selective attention to maintain an adaptive balance between prediction and surprise. This view of active sleep has some interesting implications for the evolution of subjective awareness and consciousness in animals.
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Affiliation(s)
| | - Bruno van Swinderen
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
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13
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Hulse BK, Haberkern H, Franconville R, Turner-Evans DB, Takemura SY, Wolff T, Noorman M, Dreher M, Dan C, Parekh R, Hermundstad AM, Rubin GM, Jayaraman V. A connectome of the Drosophila central complex reveals network motifs suitable for flexible navigation and context-dependent action selection. eLife 2021; 10:66039. [PMID: 34696823 PMCID: PMC9477501 DOI: 10.7554/elife.66039] [Citation(s) in RCA: 122] [Impact Index Per Article: 40.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 09/07/2021] [Indexed: 11/13/2022] Open
Abstract
Flexible behaviors over long timescales are thought to engage recurrent neural networks in deep brain regions, which are experimentally challenging to study. In insects, recurrent circuit dynamics in a brain region called the central complex (CX) enable directed locomotion, sleep, and context- and experience-dependent spatial navigation. We describe the first complete electron-microscopy-based connectome of the Drosophila CX, including all its neurons and circuits at synaptic resolution. We identified new CX neuron types, novel sensory and motor pathways, and network motifs that likely enable the CX to extract the fly's head-direction, maintain it with attractor dynamics, and combine it with other sensorimotor information to perform vector-based navigational computations. We also identified numerous pathways that may facilitate the selection of CX-driven behavioral patterns by context and internal state. The CX connectome provides a comprehensive blueprint necessary for a detailed understanding of network dynamics underlying sleep, flexible navigation, and state-dependent action selection.
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Affiliation(s)
- Brad K Hulse
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Hannah Haberkern
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Romain Franconville
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | | | | | - Tanya Wolff
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Marcella Noorman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Marisa Dreher
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Chuntao Dan
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Ruchi Parekh
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | | | - Gerald M Rubin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Vivek Jayaraman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
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14
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Ramakrishnan A, Sheeba V. Gap junction protein Innexin2 modulates the period of free-running rhythms in Drosophila melanogaster. iScience 2021; 24:103011. [PMID: 34522854 PMCID: PMC8426565 DOI: 10.1016/j.isci.2021.103011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/13/2021] [Accepted: 08/17/2021] [Indexed: 10/25/2022] Open
Abstract
A neuronal circuit of ∼150 neurons modulates rhythmic activity-rest behavior of Drosophila melanogaster. While it is known that coherent ∼24-hr rhythms in locomotion are brought about when 7 distinct neuronal clusters function as a network due to chemical communication amongst them, there are no reports of communication via electrical synapses made up of gap junctions. Here, we report that gap junction proteins, Innexins play crucial roles in determining the intrinsic period of activity-rest rhythms in flies. We show the presence of Innexin2 in the ventral lateral neurons, wherein RNAi-based knockdown of its expression slows down the speed of activity-rest rhythm along with alterations in the oscillation of a core-clock protein PERIOD and the output molecule pigment dispersing factor. Specifically disrupting the channel-forming ability of Innexin2 causes period lengthening, suggesting that Innexin2 may function as hemichannels or gap junctions in the clock circuit.
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Affiliation(s)
- Aishwarya Ramakrishnan
- Chronobiology and Behavioural Neurogenetics Laboratory, Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, Karnataka 560064, India
| | - Vasu Sheeba
- Chronobiology and Behavioural Neurogenetics Laboratory, Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, Karnataka 560064, India
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15
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Abstract
Sleep is critical for diverse aspects of brain function in animals ranging from invertebrates to humans. Powerful genetic tools in the fruit fly Drosophila melanogaster have identified - at an unprecedented level of detail - genes and neural circuits that regulate sleep. This research has revealed that the functions and neural principles of sleep regulation are largely conserved from flies to mammals. Further, genetic approaches to studying sleep have uncovered mechanisms underlying the integration of sleep and many different biological processes, including circadian timekeeping, metabolism, social interactions, and aging. These findings show that in flies, as in mammals, sleep is not a single state, but instead consists of multiple physiological and behavioral states that change in response to the environment, and is shaped by life history. Here, we review advances in the study of sleep in Drosophila, discuss their implications for understanding the fundamental functions of sleep that are likely to be conserved among animal species, and identify important unanswered questions in the field.
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Affiliation(s)
- Orie T Shafer
- The Advanced Science Research Center, City University of New York, New York, NY 10031, USA.
| | - Alex C Keene
- Department of Biological Science, Florida Atlantic University, Jupiter, FL 33458, USA.
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16
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Qiu S, Sun K, Di Z. Collective Dynamics of Neural Networks With Sleep-Related Biological Drives in Drosophila. Front Comput Neurosci 2021; 15:616193. [PMID: 34012388 PMCID: PMC8126628 DOI: 10.3389/fncom.2021.616193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 03/29/2021] [Indexed: 11/18/2022] Open
Abstract
The collective electrophysiological dynamics of the brain as a result of sleep-related biological drives in Drosophila are investigated in this paper. Based on the Huber-Braun thermoreceptor model, the conductance-based neurons model is extended to a coupled neural network to analyze the local field potential (LFP). The LFP is calculated by using two different metrics: the mean value and the distance-dependent LFP. The distribution of neurons around the electrodes is assumed to have a circular or grid distribution on a two-dimensional plane. Regardless of which method is used, qualitatively similar results are obtained that are roughly consistent with the experimental data. During wake, the LFP has an irregular or a regular spike. However, the LFP becomes regular bursting during sleep. To further analyze the results, wavelet analysis and raster plots are used to examine how the LFP frequencies changed. The synchronization of neurons under different network structures is also studied. The results demonstrate that there are obvious oscillations at approximately 8 Hz during sleep that are absent during wake. Different time series of the LFP can be obtained under different network structures and the density of the network will also affect the magnitude of the potential. As the number of coupled neurons increases, the neural network becomes easier to synchronize, but the sleep and wake time described by the LFP spectrogram do not change. Moreover, the parameters that affect the durations of sleep and wake are analyzed.
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Affiliation(s)
- Shuihan Qiu
- International Academic Center of Complex Systems, Beijing Normal University at Zhuhai, Beijing, China.,School of Systems Science, Beijing Normal University, Beijing, China
| | - Kaijia Sun
- School of Systems Science, Beijing Normal University, Beijing, China
| | - Zengru Di
- International Academic Center of Complex Systems, Beijing Normal University at Zhuhai, Beijing, China.,School of Systems Science, Beijing Normal University, Beijing, China
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17
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Tainton-Heap LAL, Kirszenblat LC, Notaras ET, Grabowska MJ, Jeans R, Feng K, Shaw PJ, van Swinderen B. A Paradoxical Kind of Sleep in Drosophila melanogaster. Curr Biol 2020; 31:578-590.e6. [PMID: 33238155 DOI: 10.1016/j.cub.2020.10.081] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 09/14/2020] [Accepted: 10/27/2020] [Indexed: 01/01/2023]
Abstract
The dynamic nature of sleep in many animals suggests distinct stages that serve different functions. Genetic sleep induction methods in animal models provide a powerful way to disambiguate these stages and functions, although behavioral methods alone are insufficient to accurately identify what kind of sleep is being engaged. In Drosophila, activation of the dorsal fan-shaped body (dFB) promotes sleep, but it remains unclear what kind of sleep this is, how the rest of the fly brain is behaving, or if any specific sleep functions are being achieved. Here, we developed a method to record calcium activity from thousands of neurons across a volume of the fly brain during spontaneous sleep and compared this to dFB-induced sleep. We found that spontaneous sleep typically transitions from an active "wake-like" stage to a less active stage. In contrast, optogenetic activation of the dFB promotes sustained wake-like levels of neural activity even though flies become unresponsive to mechanical stimuli. When we probed flies with salient visual stimuli, we found that the activity of visually responsive neurons in the central brain was blocked by transient dFB activation, confirming an acute disconnect from the external environment. Prolonged optogenetic dFB activation nevertheless achieved a key sleep function by correcting visual attention defects brought on by sleep deprivation. These results suggest that dFB activation promotes a distinct form of sleep in Drosophila, where brain activity appears similar to wakefulness, but responsiveness to external sensory stimuli is profoundly suppressed.
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Affiliation(s)
- Lucy A L Tainton-Heap
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Leonie C Kirszenblat
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia; RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Eleni T Notaras
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Martyna J Grabowska
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Rhiannon Jeans
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Kai Feng
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Paul J Shaw
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Bruno van Swinderen
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
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18
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Ertekin D, Kirszenblat L, Faville R, van Swinderen B. Down-regulation of a cytokine secreted from peripheral fat bodies improves visual attention while reducing sleep in Drosophila. PLoS Biol 2020; 18:e3000548. [PMID: 32745077 PMCID: PMC7426065 DOI: 10.1371/journal.pbio.3000548] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 08/13/2020] [Accepted: 07/13/2020] [Indexed: 11/29/2022] Open
Abstract
Sleep is vital for survival. Yet under environmentally challenging conditions, such as starvation, animals suppress their need for sleep. Interestingly, starvation-induced sleep loss does not evoke a subsequent sleep rebound. Little is known about how starvation-induced sleep deprivation differs from other types of sleep loss, or why some sleep functions become dispensable during starvation. Here, we demonstrate that down-regulation of the secreted cytokine unpaired 2 (upd2) in Drosophila flies may mimic a starved-like state. We used a genetic knockdown strategy to investigate the consequences of upd2 on visual attention and sleep in otherwise well-fed flies, thereby sidestepping the negative side effects of undernourishment. We find that knockdown of upd2 in the fat body (FB) is sufficient to suppress sleep and promote feeding-related behaviors while also improving selective visual attention. Furthermore, we show that this peripheral signal is integrated in the fly brain via insulin-expressing cells. Together, these findings identify a role for peripheral tissue-to-brain interactions in the simultaneous regulation of sleep quality and attention, to potentially promote adaptive behaviors necessary for survival in hungry animals.
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Affiliation(s)
- Deniz Ertekin
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Leonie Kirszenblat
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Richard Faville
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Bruno van Swinderen
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
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19
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Scaplen KM, Talay M, Nunez KM, Salamon S, Waterman AG, Gang S, Song SL, Barnea G, Kaun KR. Circuits that encode and guide alcohol-associated preference. eLife 2020; 9:48730. [PMID: 32497004 PMCID: PMC7272191 DOI: 10.7554/elife.48730] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 05/18/2020] [Indexed: 12/21/2022] Open
Abstract
A powerful feature of adaptive memory is its inherent flexibility. Alcohol and other addictive substances can remold neural circuits important for memory to reduce this flexibility. However, the mechanism through which pertinent circuits are selected and shaped remains unclear. We show that circuits required for alcohol-associated preference shift from population level dopaminergic activation to select dopamine neurons that predict behavioral choice in Drosophila melanogaster. During memory expression, subsets of dopamine neurons directly and indirectly modulate the activity of interconnected glutamatergic and cholinergic mushroom body output neurons (MBON). Transsynaptic tracing of neurons important for memory expression revealed a convergent center of memory consolidation within the mushroom body (MB) implicated in arousal, and a structure outside the MB implicated in integration of naïve and learned responses. These findings provide a circuit framework through which dopamine neuronal activation shifts from reward delivery to cue onset, and provide insight into the maladaptive nature of memory.
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Affiliation(s)
- Kristin M Scaplen
- Department of Neuroscience, Brown University, Providence, United States
| | - Mustafa Talay
- Department of Neuroscience, Brown University, Providence, United States
| | - Kavin M Nunez
- Department of Molecular Pharmacology and Physiology, Brown University, Providence, United States
| | - Sarah Salamon
- Department of Pharmacology, University of Cologne, Cologne, Germany
| | - Amanda G Waterman
- Department of Neuroscience, Brown University, Providence, United States
| | - Sydney Gang
- Department of Biochemistry, Brown University, Providence, United States
| | - Sophia L Song
- Department of Neuroscience, Brown University, Providence, United States
| | - Gilad Barnea
- Department of Neuroscience, Brown University, Providence, United States
| | - Karla R Kaun
- Department of Neuroscience, Brown University, Providence, United States
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20
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Shyu WH, Lee WP, Chiang MH, Chang CC, Fu TF, Chiang HC, Wu T, Wu CL. Electrical synapses between mushroom body neurons are critical for consolidated memory retrieval in Drosophila. PLoS Genet 2019; 15:e1008153. [PMID: 31071084 PMCID: PMC6529013 DOI: 10.1371/journal.pgen.1008153] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 05/21/2019] [Accepted: 04/23/2019] [Indexed: 11/19/2022] Open
Abstract
Electrical synapses between neurons, also known as gap junctions, are direct cell membrane channels between adjacent neurons. Gap junctions play a role in the synchronization of neuronal network activity; however, their involvement in cognition has not been well characterized. Three-hour olfactory associative memory in Drosophila has two components: consolidated anesthesia-resistant memory (ARM) and labile anesthesia-sensitive memory (ASM). Here, we show that knockdown of the gap junction gene innexin5 (inx5) in mushroom body (MB) neurons disrupted ARM, while leaving ASM intact. Whole-mount brain immunohistochemistry indicated that INX5 protein was preferentially expressed in the somas, calyxes, and lobes regions of the MB neurons. Adult-stage-specific knockdown of inx5 in αβ neurons disrupted ARM, suggesting a specific requirement of INX5 in αβ neurons for ARM formation. Hyperpolarization of αβ neurons during memory retrieval by expressing an engineered halorhodopsin (eNpHR) also disrupted ARM. Administration of the gap junction blocker carbenoxolone (CBX) reduced the proportion of odor responsive αβ neurons to the training odor 3 hours after training. Finally, the α-branch-specific 3-hour ARM-specific memory trace was also diminished with CBX treatment and in inx5 knockdown flies. Altogether, our results suggest INX5 gap junction channels in αβ neurons for ARM retrieval and also provide a more detailed neuronal mechanism for consolidated memory in Drosophila.
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Affiliation(s)
- Wei-Huan Shyu
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Wang-Pao Lee
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Meng-Hsuan Chiang
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Ching-Ching Chang
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Department of Biochemistry, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Tsai-Feng Fu
- Department of Applied Chemistry, National Chi Nan University, Nantou, Taiwan
| | - Hsueh-Cheng Chiang
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Tony Wu
- Department of Neurology, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Chia-Lin Wu
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Department of Biochemistry, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Department of Neurology, Chang Gung Memorial Hospital, Linkou, Taiwan
- * E-mail:
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21
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Nässel DR, Zandawala M. Recent advances in neuropeptide signaling in Drosophila, from genes to physiology and behavior. Prog Neurobiol 2019; 179:101607. [PMID: 30905728 DOI: 10.1016/j.pneurobio.2019.02.003] [Citation(s) in RCA: 171] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 02/18/2019] [Accepted: 02/28/2019] [Indexed: 12/11/2022]
Abstract
This review focuses on neuropeptides and peptide hormones, the largest and most diverse class of neuroactive substances, known in Drosophila and other animals to play roles in almost all aspects of daily life, as w;1;ell as in developmental processes. We provide an update on novel neuropeptides and receptors identified in the last decade, and highlight progress in analysis of neuropeptide signaling in Drosophila. Especially exciting is the huge amount of work published on novel functions of neuropeptides and peptide hormones in Drosophila, largely due to the rapid developments of powerful genetic methods, imaging techniques and innovative assays. We critically discuss the roles of peptides in olfaction, taste, foraging, feeding, clock function/sleep, aggression, mating/reproduction, learning and other behaviors, as well as in regulation of development, growth, metabolic and water homeostasis, stress responses, fecundity, and lifespan. We furthermore provide novel information on neuropeptide distribution and organization of peptidergic systems, as well as the phylogenetic relations between Drosophila neuropeptides and those of other phyla, including mammals. As will be shown, neuropeptide signaling is phylogenetically ancient, and not only are the structures of the peptides, precursors and receptors conserved over evolution, but also many functions of neuropeptide signaling in physiology and behavior.
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Affiliation(s)
- Dick R Nässel
- Department of Zoology, Stockholm University, Stockholm, Sweden.
| | - Meet Zandawala
- Department of Zoology, Stockholm University, Stockholm, Sweden; Department of Neuroscience, Brown University, Providence, RI, USA.
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22
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Gap Junctions and NCA Cation Channels Are Critical for Developmentally Timed Sleep and Arousal in Caenorhabditis elegans. Genetics 2018; 210:1369-1381. [PMID: 30323068 DOI: 10.1534/genetics.118.301551] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 10/10/2018] [Indexed: 12/16/2022] Open
Abstract
An essential characteristic of sleep is heightened arousal threshold, with decreased behavioral response to external stimuli. The molecular and cellular mechanisms underlying arousal threshold changes during sleep are not fully understood. We report that loss of UNC-7 or UNC-9 innexin function dramatically reduced sleep and decreased arousal threshold during developmentally timed sleep in Caenorhabditis elegans UNC-7 function was required in premotor interneurons and UNC-9 function was required in motor neurons in this paradigm. Simultaneous transient overexpression of UNC-7 and UNC-9 was sufficient to induce anachronistic sleep in adult animals. Moreover, loss of UNC-7 or UNC-9 suppressed the increased sleep of EGL-4 gain-of-function animals, which have increased cyclic-GMP-dependent protein kinase activity. These results suggest C. elegans gap junctions may act downstream of previously identified sleep regulators. In other paradigms, the NCA cation channels act upstream of gap junctions. Consistent with this, diminished NCA channel activity in C. elegans robustly increased arousal thresholds during sleep bouts in L4-to-adult developmentally timed sleep. Total time in sleep bouts was only modestly increased in animals lacking NCA channel auxiliary subunit UNC-79, whereas increased channel activity dramatically decreased sleep. Loss of EGL-4 or innexin proteins suppressed UNC-79 loss-of-function sleep and arousal defects. In Drosophila, the ion channel narrow abdomen, an ortholog of the C. elegans NCA channels, drive the pigment dispersing factor (PDF) neuropeptide release, regulating circadian behavior. However, in C. elegans, we found that loss of the PDF receptor PDFR-1 did not suppress gain-of-function sleep defects, suggesting an alternative downstream pathway. This study emphasizes the conservation and importance of neuronal activity modulation during sleep, and unequivocally demonstrates that gap junction function is critical for normal sleep.
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