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Larnerd C, Kachewar N, Wolf FW. Drosophila learning and memory centers and the actions of drugs of abuse. Learn Mem 2024; 31:a053815. [PMID: 38862166 PMCID: PMC11199947 DOI: 10.1101/lm.053815.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 03/27/2024] [Indexed: 06/13/2024]
Abstract
Drug addiction and the circuitry for learning and memory are intimately intertwined. Drugs of abuse create strong, inappropriate, and lasting memories that contribute to many of their destructive properties, such as continued use despite negative consequences and exceptionally high rates of relapse. Studies in Drosophila melanogaster are helping us understand how drugs of abuse, especially alcohol, create memories at the level of individual neurons and in the circuits where they function. Drosophila is a premier organism for identifying the mechanisms of learning and memory. Drosophila also respond to drugs of abuse in ways that remarkably parallel humans and rodent models. An emerging consensus is that, for alcohol, the mushroom bodies participate in the circuits that control acute drug sensitivity, not explicitly associative forms of plasticity such as tolerance, and classical associative memories of their rewarding and aversive properties. Moreover, it is becoming clear that drugs of abuse use the mushroom body circuitry differently from other behaviors, potentially providing a basis for their addictive properties.
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Affiliation(s)
- Caleb Larnerd
- Quantitative and Systems Biology Graduate Group, University of California, Merced, California 95343, USA
| | - Neha Kachewar
- Department of Molecular and Cell Biology, University of California, Merced, California 95343, USA
- Health Sciences Research Institute, University of California, Merced, California 95343, USA
| | - Fred W Wolf
- Quantitative and Systems Biology Graduate Group, University of California, Merced, California 95343, USA
- Department of Molecular and Cell Biology, University of California, Merced, California 95343, USA
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2
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Scaplen KM, Kaun KR. Dopamine determines how reward overrides risk. Nature 2023; 623:258-259. [PMID: 37880521 DOI: 10.1038/d41586-023-03085-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2023]
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3
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Vannan A, Dell’Orco M, Perrone-Bizzozero NI, Neisewander JL, Wilson MA. An approach for prioritizing candidate genes from RNA-seq using preclinical cocaine self-administration datasets as a test case. G3 (BETHESDA, MD.) 2023; 13:jkad143. [PMID: 37433118 PMCID: PMC10542560 DOI: 10.1093/g3journal/jkad143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 06/03/2023] [Accepted: 06/07/2023] [Indexed: 07/13/2023]
Abstract
RNA-sequencing (RNA-seq) technology has led to a surge of neuroscience research using animal models to probe the complex molecular mechanisms underlying brain function and behavior, including substance use disorders. However, findings from rodent studies often fail to be translated into clinical treatments. Here, we developed a novel pipeline for narrowing candidate genes from preclinical studies by translational potential and demonstrated its utility in 2 RNA-seq studies of rodent self-administration. This pipeline uses evolutionary conservation and preferential expression of genes across brain tissues to prioritize candidate genes, increasing the translational utility of RNA-seq in model organisms. Initially, we demonstrate the utility of our prioritization pipeline using an uncorrected P-value. However, we found no differentially expressed genes in either dataset after correcting for multiple testing with false discovery rate (FDR < 0.05 or <0.1). This is likely due to low statistical power that is common across rodent behavioral studies, and, therefore, we additionally illustrate the use of our pipeline on a third dataset with differentially expressed genes corrected for multiple testing (FDR < 0.05). We also advocate for improved RNA-seq data collection, statistical testing, and metadata reporting that will bolster the field's ability to identify reliable candidate genes and improve the translational value of bioinformatics in rodent research.
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Affiliation(s)
- Annika Vannan
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
| | - Michela Dell’Orco
- Department of Neurosciences, University of New Mexico Health Science Center, University of New Mexico, Albuquerque, NM 87131-0001, USA
| | - Nora I Perrone-Bizzozero
- Department of Neurosciences, University of New Mexico Health Science Center, University of New Mexico, Albuquerque, NM 87131-0001, USA
| | - Janet L Neisewander
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
| | - Melissa A Wilson
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ 85287-4501, USA
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4
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Dresp-Langley B. From Reward to Anhedonia-Dopamine Function in the Global Mental Health Context. Biomedicines 2023; 11:2469. [PMID: 37760910 PMCID: PMC10525914 DOI: 10.3390/biomedicines11092469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 08/29/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023] Open
Abstract
When "hijacked" by compulsive behaviors that affect the reward and stress centers of the brain, functional changes in the dopamine circuitry occur as the consequence of pathological brain adaptation. As a brain correlate of mental health, dopamine has a central functional role in behavioral regulation from healthy reward-seeking to pathological adaptation to stress in response to adversity. This narrative review offers a spotlight view of the transition from healthy reward function, under the control of dopamine, to the progressive deregulation of this function in interactions with other brain centers and circuits, producing what may be called an anti-reward brain state. How such deregulation is linked to specific health-relevant behaviors is then explained and linked to pandemic-related adversities and the stresses they engendered. The long lockdown periods where people in social isolation had to rely on drink, food, and digital rewards via the internet may be seen as the major triggers of changes in motivation and reward-seeking behavior worldwide. The pathological adaptation of dopamine-mediated reward circuitry in the brain is discussed. It is argued that, when pushed by fate and circumstance into a physiological brain state of anti-reward, human behavior changes and mental health is affected, depending on individual vulnerabilities. A unified conceptual account that places dopamine function at the centre of the current global mental health context is proposed.
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Affiliation(s)
- Birgitta Dresp-Langley
- Centre National de la Recherche Scientifique, UMR 7357 ICube CNRS, Université de Strasbourg Hôpitaux Universitaires Faculté de Médecine, Pavillon Clovis Vincent, 4 Rue Kirschleger, CEDEX, 67085 Strasbourg, France
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5
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Garrett EC, Bielawski AM, Ruchti E, Sherer LM, Waghmare I, Hess-Homeier D, McCabe BD, Stowers RS, Certel SJ. The matricellular protein Drosophila Cellular Communication Network Factor is required for synaptic transmission and female fertility. Genetics 2023; 223:iyac190. [PMID: 36602539 PMCID: PMC9991515 DOI: 10.1093/genetics/iyac190] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 11/16/2022] [Accepted: 11/17/2022] [Indexed: 01/06/2023] Open
Abstract
Within the extracellular matrix, matricellular proteins are dynamically expressed nonstructural proteins that interact with cell surface receptors, growth factors, and proteases, as well as with structural matrix proteins. The cellular communication network factors family of matricellular proteins serve regulatory roles to regulate cell function and are defined by their conserved multimodular organization. Here, we characterize the expression and neuronal requirement for the Drosophila cellular communication network factor family member. Drosophila cellular communication network factor is expressed in the nervous system throughout development including in subsets of monoamine-expressing neurons. Drosophila cellular communication network factor-expressing abdominal ganglion neurons innervate the ovaries and uterus and the loss of Drosophila cellular communication network factor results in reduced female fertility. In addition, Drosophila cellular communication network factor accumulates at the synaptic cleft and is required for neurotransmission at the larval neuromuscular junction. Analyzing the function of the single Drosophila cellular communication network factor family member will enhance our potential to understand how the microenvironment impacts neurotransmitter release in distinct cellular contexts and in response to activity.
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Affiliation(s)
| | - Ashley M Bielawski
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Evelyne Ruchti
- Brain Mind Institute, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
| | - Lewis M Sherer
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Indrayani Waghmare
- Department of Cell and Developmental Biology, Program in Developmental Biology, Vanderbilt-Ingram Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - David Hess-Homeier
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Brian D McCabe
- Brain Mind Institute, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
| | - R Steven Stowers
- Department of Cell Biology and Microbiology, Montana State University, Bozeman, MT 59717, USA
| | - Sarah J Certel
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
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6
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Shekar A, Mabry SJ, Cheng MH, Aguilar JI, Patel S, Zanella D, Saleeby DP, Zhu Y, Romanazzi T, Ulery-Reynolds P, Bahar I, Carter AM, Matthies HJG, Galli A. Syntaxin 1 Ser 14 phosphorylation is required for nonvesicular dopamine release. SCIENCE ADVANCES 2023; 9:eadd8417. [PMID: 36630507 PMCID: PMC9833662 DOI: 10.1126/sciadv.add8417] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 12/14/2022] [Indexed: 05/30/2023]
Abstract
Amphetamine (AMPH) is a psychostimulant that is commonly abused. The stimulant properties of AMPH are associated with its ability to increase dopamine (DA) neurotransmission. This increase is promoted by nonvesicular DA release mediated by reversal of DA transporter (DAT) function. Syntaxin 1 (Stx1) is a SNARE protein that is phosphorylated at Ser14 by casein kinase II. We show that Stx1 phosphorylation is critical for AMPH-induced nonvesicular DA release and, in Drosophila melanogaster, regulates the expression of AMPH-induced preference and sexual motivation. Our molecular dynamics simulations of the DAT/Stx1 complex demonstrate that phosphorylation of these proteins is pivotal for DAT to dwell in a DA releasing state. This state is characterized by the breakdown of two key salt bridges within the DAT intracellular gate, causing the opening and hydration of the DAT intracellular vestibule, allowing DA to bind from the cytosol, a mechanism that we hypothesize underlies nonvesicular DA release.
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Affiliation(s)
- Aparna Shekar
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Samuel J. Mabry
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Mary H. Cheng
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jenny I. Aguilar
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Shalin Patel
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Daniele Zanella
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - David P. Saleeby
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Yanqi Zhu
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Tiziana Romanazzi
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | | | - Ivet Bahar
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Angela M. Carter
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | | | - Aurelio Galli
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
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7
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Yu JX, Xiang Q, Qu JB, Hui YM, Lin T, Zeng XN, Liu JL. Octopaminergic neurons function in appetitive but not aversive olfactory learning and memory in Bactrocera dorsalis. INSECT SCIENCE 2022; 29:1747-1760. [PMID: 35189034 DOI: 10.1111/1744-7917.13023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 01/17/2022] [Accepted: 02/02/2022] [Indexed: 06/14/2023]
Abstract
The biogenic amine octopamine (OA, invertebrate counterpart of noradrenaline) plays critical roles in the regulation of olfactory behavior. Historically, OA has been thought to mediate appetitive but not aversive learning in honeybees, fruit flies (Drosophila), and crickets. However, this viewpoint has recently been challenged because OA activity through a β-adrenergic-like receptor drives both appetitive and aversive learning. Here, we explored the roles of OA neurons in olfactory learning and memory retrieval in Bactrocera dorsalis. We trained flies to associate an orange odor with a sucrose reward or to associate methyl eugenol, a male lure, with N,N-diethyl-3-methyl benzoyl amide (DEET) punishment. We then treated flies with OA receptor antagonists before appetitive or aversive conditioning and a memory retention test. Injection of OA receptor antagonist mianserin or epinastine into the abdomen of flies led to impaired of appetitive learning and memory retention with a sucrose reward, while aversive learning and memory retention with DEET punishment remained intact. Our results suggest that the OA signaling participates in appetitive but not aversive learning and memory retrieval in B. dorsalis through OA receptors.
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Affiliation(s)
- Jin-Xin Yu
- Guangdong Engineering Research Center for Insect Behavior Regulation, College of Plant Protection, South China Agricultural University, Guangzhou, Guangdong, China
| | - Qian Xiang
- Guangdong Engineering Research Center for Insect Behavior Regulation, College of Plant Protection, South China Agricultural University, Guangzhou, Guangdong, China
| | - Jia-Bao Qu
- Guangdong Engineering Research Center for Insect Behavior Regulation, College of Plant Protection, South China Agricultural University, Guangzhou, Guangdong, China
| | - Yan-Min Hui
- Guangdong Engineering Research Center for Insect Behavior Regulation, College of Plant Protection, South China Agricultural University, Guangzhou, Guangdong, China
| | - Tao Lin
- Guangdong Engineering Research Center for Insect Behavior Regulation, College of Plant Protection, South China Agricultural University, Guangzhou, Guangdong, China
- College of Life Sciences, Department of Biological Science, Shangrao Normal University, Shangrao, Jiangxi, China
| | - Xin-Nian Zeng
- Guangdong Engineering Research Center for Insect Behavior Regulation, College of Plant Protection, South China Agricultural University, Guangzhou, Guangdong, China
| | - Jia-Li Liu
- Guangdong Engineering Research Center for Insect Behavior Regulation, College of Plant Protection, South China Agricultural University, Guangzhou, Guangdong, China
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8
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Dvořáček J, Kodrík D. Drug effect and addiction research with insects - From Drosophila to collective reward in honeybees. Neurosci Biobehav Rev 2022; 140:104816. [PMID: 35940307 DOI: 10.1016/j.neubiorev.2022.104816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 07/29/2022] [Accepted: 08/01/2022] [Indexed: 10/16/2022]
Abstract
Animals and humans share similar reactions to the effects of addictive substances, including those of their brain networks to drugs. Our review focuses on simple invertebrate models, particularly the honeybee (Apis mellifera), and on the effects of drugs on bee behaviour and brain functions. The drug effects in bees are very similar to those described in humans. Furthermore, the honeybee community is a superorganism in which many collective functions outperform the simple sum of individual functions. The distribution of reward functions in this superorganism is unique - although sublimated at the individual level, community reward functions are of higher quality. This phenomenon of collective reward may be extrapolated to other animal species living in close and strictly organised societies, i.e. humans. The relationship between sociality and reward, based on use of similar parts of the neural network (social decision-making network in mammals, mushroom body in bees), suggests a functional continuum of reward and sociality in animals.
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Affiliation(s)
- Jiří Dvořáček
- Institute of Entomology, Biology Centre, Czech Academy of Sciences, Branišovská 31, 370 05, České Budĕjovice, Czech Republic; Faculty of Science, University of South Bohemia, Branišovská 31, 370 05, České Budĕjovice, Czech Republic.
| | - Dalibor Kodrík
- Institute of Entomology, Biology Centre, Czech Academy of Sciences, Branišovská 31, 370 05, České Budĕjovice, Czech Republic; Faculty of Science, University of South Bohemia, Branišovská 31, 370 05, České Budĕjovice, Czech Republic
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9
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Alcohol, neuronal plasticity, and mitochondrial trafficking. Proc Natl Acad Sci U S A 2022; 119:e2208744119. [PMID: 35858366 PMCID: PMC9303853 DOI: 10.1073/pnas.2208744119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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10
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Digital Addiction and Sleep. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19116910. [PMID: 35682491 PMCID: PMC9179985 DOI: 10.3390/ijerph19116910] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 06/02/2022] [Accepted: 06/03/2022] [Indexed: 12/25/2022]
Abstract
In 2020, the World Health Organization formally recognized addiction to digital technology (connected devices) as a worldwide problem, where excessive online activity and internet use lead to inability to manage time, energy, and attention during daytime and produce disturbed sleep patterns or insomnia during nighttime. Recent studies have shown that the problem has increased in magnitude worldwide during the COVID-19 pandemic. The extent to which dysfunctional sleep is a consequence of altered motivation, memory function, mood, diet, and other lifestyle variables or results from excess of blue-light exposure when looking at digital device screens for long hours at day and night is one of many still unresolved questions. This article offers a narrative overview of some of the most recent literature on this topic. The analysis provided offers a conceptual basis for understanding digital addiction as one of the major reasons why people, and adolescents in particular, sleep less and less well in the digital age. It discusses definitions as well as mechanistic model accounts in context. Digital addiction is identified as functionally equivalent to all addictions, characterized by the compulsive, habitual, and uncontrolled use of digital devices and an excessively repeated engagement in a particular online behavior. Once the urge to be online has become uncontrollable, it is always accompanied by severe sleep loss, emotional distress, depression, and memory dysfunction. In extreme cases, it may lead to suicide. The syndrome has been linked to the known chronic effects of all drugs, producing disturbances in cellular and molecular mechanisms of the GABAergic and glutamatergic neurotransmitter systems. Dopamine and serotonin synaptic plasticity, essential for impulse control, memory, and sleep function, are measurably altered. The full spectrum of behavioral symptoms in digital addicts include eating disorders and withdrawal from outdoor and social life. Evidence pointing towards dysfunctional melatonin and vitamin D metabolism in digital addicts should be taken into account for carving out perspectives for treatment. The conclusions offer a holistic account for digital addiction, where sleep deficit is one of the key factors.
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11
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Flavell SW, Gordus A. Dynamic functional connectivity in the static connectome of Caenorhabditis elegans. Curr Opin Neurobiol 2022; 73:102515. [PMID: 35183877 PMCID: PMC9621599 DOI: 10.1016/j.conb.2021.12.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 12/16/2021] [Accepted: 12/22/2021] [Indexed: 01/01/2023]
Abstract
A hallmark of adaptive behavior is the ability to flexibly respond to sensory cues. To understand how neural circuits implement this flexibility, it is critical to resolve how a static anatomical connectome can be modulated such that functional connectivity in the network can be dynamically regulated. Here, we review recent work in the roundworm Caenorhabditis elegans on this topic. EM studies have mapped anatomical connectomes of many C. elegans animals, highlighting the level of stereotypy in the anatomical network. Brain-wide calcium imaging and studies of specified neural circuits have uncovered striking flexibility in the functional coupling of neurons. The coupling between neurons is controlled by neuromodulators that act over long timescales. This gives rise to persistent behavioral states that animals switch between, allowing them to generate adaptive behavioral responses across environmental conditions. Thus, the dynamic coupling of neurons enables multiple behavioral states to be encoded in a physically stereotyped connectome.
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Affiliation(s)
- Steven W Flavell
- Picower Institute for Learning and Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Andrew Gordus
- Department of Biology, Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA.
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12
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Dvořáček J, Bednářová A, Krishnan N, Kodrík D. Dopaminergic muhsroom body neurons in Drosophila: flexibility of neuron identity in a model organism? Neurosci Biobehav Rev 2022; 135:104570. [DOI: 10.1016/j.neubiorev.2022.104570] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 02/03/2022] [Accepted: 02/03/2022] [Indexed: 11/28/2022]
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Abstract
In this review, we highlight sources of alcohols in nature, as well as the behavioral and ecological roles that these fermentation cues play in the short lifespan of Drosophila melanogaster. With a focus on neuroethology, we describe the olfactory detection of alcohol as well as ensuing neural signaling within the brain of the fly. We proceed to explain the plethora of behaviors related to alcohol, including attraction, feeding, and oviposition, as well as general effects on aggression and courtship. All of these behaviors are shaped by physiological state and social contexts. In a comparative perspective, we also discuss inter- and intraspecies differences related to alcohol tolerance and metabolism. Lastly, we provide corollaries with other dipteran and coleopteran insect species that also have olfactory systems attuned to ethanol detection and describe ecological and evolutionary directions for further studies of the natural history of alcohol and the fly.
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Affiliation(s)
- Ian W Keesey
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588, USA;
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, D-07745 Jena, Germany;
| | - Bill S Hansson
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, D-07745 Jena, Germany;
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14
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Srinivasan C, Phan BN, Lawler AJ, Ramamurthy E, Kleyman M, Brown AR, Kaplow IM, Wirthlin ME, Pfenning AR. Addiction-Associated Genetic Variants Implicate Brain Cell Type- and Region-Specific Cis-Regulatory Elements in Addiction Neurobiology. J Neurosci 2021; 41:9008-9030. [PMID: 34462306 PMCID: PMC8549541 DOI: 10.1523/jneurosci.2534-20.2021] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 06/18/2021] [Accepted: 07/10/2021] [Indexed: 12/14/2022] Open
Abstract
Recent large genome-wide association studies have identified multiple confident risk loci linked to addiction-associated behavioral traits. Most genetic variants linked to addiction-associated traits lie in noncoding regions of the genome, likely disrupting cis-regulatory element (CRE) function. CREs tend to be highly cell type-specific and may contribute to the functional development of the neural circuits underlying addiction. Yet, a systematic approach for predicting the impact of risk variants on the CREs of specific cell populations is lacking. To dissect the cell types and brain regions underlying addiction-associated traits, we applied stratified linkage disequilibrium score regression to compare genome-wide association studies to genomic regions collected from human and mouse assays for open chromatin, which is associated with CRE activity. We found enrichment of addiction-associated variants in putative CREs marked by open chromatin in neuronal (NeuN+) nuclei collected from multiple prefrontal cortical areas and striatal regions known to play major roles in reward and addiction. To further dissect the cell type-specific basis of addiction-associated traits, we also identified enrichments in human orthologs of open chromatin regions of female and male mouse neuronal subtypes: cortical excitatory, D1, D2, and PV. Last, we developed machine learning models to predict mouse cell type-specific open chromatin, enabling us to further categorize human NeuN+ open chromatin regions into cortical excitatory or striatal D1 and D2 neurons and predict the functional impact of addiction-associated genetic variants. Our results suggest that different neuronal subtypes within the reward system play distinct roles in the variety of traits that contribute to addiction.SIGNIFICANCE STATEMENT We combine statistical genetic and machine learning techniques to find that the predisposition to for nicotine, alcohol, and cannabis use behaviors can be partially explained by genetic variants in conserved regulatory elements within specific brain regions and neuronal subtypes of the reward system. Our computational framework can flexibly integrate open chromatin data across species to screen for putative causal variants in a cell type- and tissue-specific manner for numerous complex traits.
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Affiliation(s)
- Chaitanya Srinivasan
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - BaDoi N Phan
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
- Medical Scientist Training Program, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
| | - Alyssa J Lawler
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Easwaran Ramamurthy
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Michael Kleyman
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Ashley R Brown
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Irene M Kaplow
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Morgan E Wirthlin
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Andreas R Pfenning
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
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15
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A network of phosphatidylinositol (4,5)-bisphosphate (PIP 2) binding sites on the dopamine transporter regulates amphetamine behavior in Drosophila Melanogaster. Mol Psychiatry 2021; 26:4417-4430. [PMID: 31796894 PMCID: PMC7266731 DOI: 10.1038/s41380-019-0620-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 11/15/2019] [Accepted: 11/21/2019] [Indexed: 12/19/2022]
Abstract
Reward modulates the saliency of a specific drug exposure and is essential for the transition to addiction. Numerous human PET-fMRI studies establish a link between midbrain dopamine (DA) release, DA transporter (DAT) availability, and reward responses. However, how and whether DAT function and regulation directly participate in reward processes remains elusive. Here, we developed a novel experimental paradigm in Drosophila melanogaster to study the mechanisms underlying the psychomotor and rewarding properties of amphetamine (AMPH). AMPH principally mediates its pharmacological and behavioral effects by increasing DA availability through the reversal of DAT function (DA efflux). We have previously shown that the phospholipid, phosphatidylinositol (4, 5)-bisphosphate (PIP2), directly interacts with the DAT N-terminus to support DA efflux in response to AMPH. In this study, we demonstrate that the interaction of PIP2 with the DAT N-terminus is critical for AMPH-induced DAT phosphorylation, a process required for DA efflux. We showed that PIP2 also interacts with intracellular loop 4 at R443. Further, we identified that R443 electrostatically regulates DA efflux as part of a coordinated interaction with the phosphorylated N-terminus. In Drosophila, we determined that a neutralizing substitution at R443 inhibited the psychomotor actions of AMPH. We associated this inhibition with a decrease in AMPH-induced DA efflux in isolated fly brains. Notably, we showed that the electrostatic interactions of R443 specifically regulate the rewarding properties of AMPH without affecting AMPH aversion. We present the first evidence linking PIP2, DAT, DA efflux, and phosphorylation processes with AMPH reward.
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16
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Faillace MP, Bernabeu RO. Epigenetic Mechanisms Mediate Nicotine-Induced Reward and Behaviour in Zebrafish. Curr Neuropharmacol 2021; 20:510-523. [PMID: 34279203 PMCID: PMC9608226 DOI: 10.2174/1570159x19666210716112351] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 06/03/2021] [Accepted: 07/11/2021] [Indexed: 11/26/2022] Open
Abstract
Nicotine induces long-term changes in the neural activity of the mesocorticolimbic reward pathway structures. The mechanisms involved in this process have not been fully characterized. The hypothesis discussed here proposed that epigenetic regulation participates in the installation of persistent adaptations and long-lasting synaptic plasticity generated by nicotine action on the mesolimbic dopamine neurons of zebrafish. The epigenetic mechanisms induced by nicotine entail histone and DNA chemical modifications, which have been described to lead to changes in gene expression. Among the enzymes that catalyze epigenetic chemical modifications, histone deacetylases (HDACs) remove acetyl groups from histones, thereby facilitating DNA relaxation and making DNA more accessible to gene transcription. DNA methylation, which is dependent on DNA methyltransferase (DNMTs) activity, inhibits gene expression by recruiting several methyl binding proteins that prevent RNA polymerase binding to DNA. In zebrafish, phenylbutyrate (PhB), an HDAC inhibitor, abolishes nicotine rewarding properties together with a series of typical reward-associated behaviors. Furthermore, PhB and nicotine alter long- and short-term object recognition memory in zebrafish, respectively. Regarding DNA methylation effects, a methyl group donor L-methionine (L-met) was found to dramatically reduce nicotine-induced conditioned place preference (CPP) in zebrafish. Simultaneous treatment with DNMT inhibitor 5-aza-2’-deoxycytidine (AZA) was found to reverse the L-met effect on nicotine-induced CPP as well as nicotine reward-specific effects on genetic expression in zebrafish. Therefore, pharmacological interventions that modulate epigenetic regulation of gene expression should be considered as a potential therapeutic method to treat nicotine addiction.
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Affiliation(s)
- Maria Paula Faillace
- Departamento de Fisiología, Facultad de Medicina e Instituto de Fisiología y Biofísica Profesor Bernardo Houssay (IFIBIO-Houssay, CONICET-UBA), Universidad de Buenos Aires (UBA), Ciudad Autónoma de Buenos Aires, Argentina
| | - Ramón O Bernabeu
- Departamento de Fisiología, Facultad de Medicina e Instituto de Fisiología y Biofísica Profesor Bernardo Houssay (IFIBIO-Houssay, CONICET-UBA), Universidad de Buenos Aires (UBA), Ciudad Autónoma de Buenos Aires, Argentina
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17
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Neurochemical Signaling of Reward and Aversion to Ventral Tegmental Area Glutamate Neurons. J Neurosci 2021; 41:5471-5486. [PMID: 34001626 DOI: 10.1523/jneurosci.1419-20.2021] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 04/29/2021] [Accepted: 05/05/2021] [Indexed: 12/21/2022] Open
Abstract
Ventral tegmental area (VTA) glutamate neurons signal and participate in reward and aversion-based behaviors. However, the neurochemical mechanisms that underlie how these neurons contribute to motivated behaviors is unknown. We used a combination of optical sensors to identify how distinct neurochemical inputs to VTA glutamate neurons participate in motivated behavior within female and male transgenic mice. Activity of glutamate inputs to VTA glutamate neurons increased for both reward-predicting and aversion-predicting cues and aversive outcomes, but subpopulations of glutamate inputs were increased or decreased by reward. For both reward and aversion-based cues and outcomes, activity of GABA inputs to VTA glutamate neurons mostly decreased. GCaMP recordings showed overall population increases in VTA glutamate neuron intracellular calcium during reward and aversion-based cues and outcomes. Electrophysiological recordings of VTA VGluT2 neurons showed that glutamate receptor activation increases firing while loss of excitation via glutamate receptor blockade decreases firing. GABA-A receptor activation decreased VTA glutamate neuron firing but GABA-A receptor blockade did not significantly change VTA glutamate neuron firing. Electrophysiological recordings in coordination with our sensor data suggest that glutamate inputs strongly regulate VTA glutamate neuron participation in diverse motivated behaviors.SIGNIFICANCE STATEMENT Glutamate and GABA are the primary excitatory and inhibitory neurotransmitters of the nervous system. However, identifying how these neurotransmitters regulate motivated behavior has remained challenging because of a lack of tools (1) capable of measuring neurotransmission at the temporal scale of motivated behaviors and (2) capable of capturing chemical signaling onto genetically-distinct neuronal populations. We have overcome these obstacles by implementing genetically-encoded fluorescent indicators to monitor both glutamate and GABA input dynamics exclusively to ventral tegmental area (VTA) glutamate neurons during reward and aversion-based behaviors. We identify that glutamate and GABA inputs to VTA glutamate neurons differentially and dynamically signal reward and aversion-based cues and outcomes. This research provides foundational evidence that links distinct neurotransmitters to motivated behaviors regulated by VTA glutamate neurons.
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18
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Thoener J, König C, Weiglein A, Toshima N, Mancini N, Amin F, Schleyer M. Associative learning in larval and adult Drosophila is impaired by the dopamine-synthesis inhibitor 3-Iodo-L-tyrosine. Biol Open 2021; 10:269081. [PMID: 34106227 PMCID: PMC8214425 DOI: 10.1242/bio.058198] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 05/04/2021] [Indexed: 11/30/2022] Open
Abstract
Across the animal kingdom, dopamine plays a crucial role in conferring reinforcement signals that teach animals about the causal structure of the world. In the fruit fly Drosophila melanogaster, dopaminergic reinforcement has largely been studied using genetics, whereas pharmacological approaches have received less attention. Here, we apply the dopamine-synthesis inhibitor 3-Iodo-L-tyrosine (3IY), which causes acute systemic inhibition of dopamine signaling, and investigate its effects on Pavlovian conditioning. We find that 3IY feeding impairs sugar-reward learning in larvae while leaving task-relevant behavioral faculties intact, and that additional feeding of a precursor of dopamine (L-3,4-dihydroxyphenylalanine, L-DOPA), rescues this impairment. Concerning a different developmental stage and for the aversive valence domain. Moreover, we demonstrate that punishment learning by activating the dopaminergic neuron PPL1-γ1pedc in adult flies is also impaired by 3IY feeding, and can likewise be rescued by L-DOPA. Our findings exemplify the advantages of using a pharmacological approach in combination with the genetic techniques available in D. melanogaster to manipulate neuronal and behavioral function. Summary: We surveyed the effects of a dopamine-synthesis inhibitor on associative learning in larval and adult Drosophila. This approach can supplement genetic tools in investigating the conserved reinforcing function of dopamine.
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Affiliation(s)
- Juliane Thoener
- Leibniz Institute for Neurobiology, Department of Genetics, 39118 Magdeburg, Germany
| | - Christian König
- Leibniz Institute for Neurobiology, Department of Genetics, 39118 Magdeburg, Germany
| | - Aliće Weiglein
- Leibniz Institute for Neurobiology, Department of Genetics, 39118 Magdeburg, Germany
| | - Naoko Toshima
- Leibniz Institute for Neurobiology, Department of Genetics, 39118 Magdeburg, Germany
| | - Nino Mancini
- Leibniz Institute for Neurobiology, Department of Genetics, 39118 Magdeburg, Germany
| | - Fatima Amin
- Leibniz Institute for Neurobiology, Department of Genetics, 39118 Magdeburg, Germany
| | - Michael Schleyer
- Leibniz Institute for Neurobiology, Department of Genetics, 39118 Magdeburg, Germany
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19
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Abstract
Addiction is a disease characterized by compulsive drug seeking and consumption observed in 20-30% of users. An addicted individual will favor drug reward over natural rewards, despite major negative consequences. Mechanistic research on rodents modeling core components of the disease has identified altered synaptic transmission as the functional substrate of pathological behavior. While the initial version of a circuit model for addiction focused on early drug adaptive behaviors observed in all individuals, it fell short of accounting for the stochastic nature of the transition to compulsion. The model builds on the initial pharmacological effect common to all addictive drugs-an increase in dopamine levels in the mesolimbic system. Here, we consolidate this early model by integrating circuits underlying compulsion and negative reinforcement. We discuss the genetic and epigenetic correlates of individual vulnerability. Many recent data converge on a gain-of-function explanation for circuit remodeling, revealing blueprints for novel addiction therapies.
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Affiliation(s)
- Christian Lüscher
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, CH-1211 Geneva, Switzerland; .,Clinic of Neurology, Department of Clinical Neurosciences, Geneva University Hospital, CH-1211 Geneva, Switzerland
| | - Patricia H Janak
- Department of Psychological and Brain Sciences, Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, Maryland 21218, USA.,The Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, USA
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20
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Dvořáček J, Kodrík D. Drosophila reward system - A summary of current knowledge. Neurosci Biobehav Rev 2021; 123:301-319. [PMID: 33421541 DOI: 10.1016/j.neubiorev.2020.12.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 12/16/2020] [Accepted: 12/27/2020] [Indexed: 01/19/2023]
Abstract
The fruit fly Drosophila melanogaster brain is the most extensively investigated model of a reward system in insects. Drosophila can discriminate between rewarding and punishing environmental stimuli and consequently undergo associative learning. Functional models, especially those modelling mushroom bodies, are constantly being developed using newly discovered information, adding to the complexity of creating a simple model of the reward system. This review aims to clarify whether its reward system also includes a hedonic component. Neurochemical systems that mediate the 'wanting' component of reward in the Drosophila brain are well documented, however, the systems that mediate the pleasure component of reward in mammals, including those involving the endogenous opioid and endocannabinoid systems, are unlikely to be present in insects. The mushroom body components exhibit differential developmental age and different functional processes. We propose a hypothetical hierarchy of the levels of reinforcement processing in response to particular stimuli, and the parallel processes that take place concurrently. The possible presence of activity-silencing and meta-satiety inducing levels in Drosophila should be further investigated.
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Affiliation(s)
- Jiří Dvořáček
- Institute of Entomology, Biology Centre, CAS, and Faculty of Science, University of South Bohemia, Branišovská 31, 370 05 České Budějovice, Czech Republic.
| | - Dalibor Kodrík
- Institute of Entomology, Biology Centre, CAS, and Faculty of Science, University of South Bohemia, Branišovská 31, 370 05 České Budějovice, Czech Republic
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21
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Siju KP, De Backer JF, Grunwald Kadow IC. Dopamine modulation of sensory processing and adaptive behavior in flies. Cell Tissue Res 2021; 383:207-225. [PMID: 33515291 PMCID: PMC7873103 DOI: 10.1007/s00441-020-03371-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 11/26/2020] [Indexed: 12/31/2022]
Abstract
Behavioral flexibility for appropriate action selection is an advantage when animals are faced with decisions that will determine their survival or death. In order to arrive at the right decision, animals evaluate information from their external environment, internal state, and past experiences. How these different signals are integrated and modulated in the brain, and how context- and state-dependent behavioral decisions are controlled are poorly understood questions. Studying the molecules that help convey and integrate such information in neural circuits is an important way to approach these questions. Many years of work in different model organisms have shown that dopamine is a critical neuromodulator for (reward based) associative learning. However, recent findings in vertebrates and invertebrates have demonstrated the complexity and heterogeneity of dopaminergic neuron populations and their functional implications in many adaptive behaviors important for survival. For example, dopaminergic neurons can integrate external sensory information, internal and behavioral states, and learned experience in the decision making circuitry. Several recent advances in methodologies and the availability of a synaptic level connectome of the whole-brain circuitry of Drosophila melanogaster make the fly an attractive system to study the roles of dopamine in decision making and state-dependent behavior. In particular, a learning and memory center-the mushroom body-is richly innervated by dopaminergic neurons that enable it to integrate multi-modal information according to state and context, and to modulate decision-making and behavior.
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Affiliation(s)
- K. P. Siju
- School of Life Sciences, Department of Molecular Life Sciences, Technical University of Munich, 85354 Freising, Germany
| | - Jean-Francois De Backer
- School of Life Sciences, Department of Molecular Life Sciences, Technical University of Munich, 85354 Freising, Germany
| | - Ilona C. Grunwald Kadow
- School of Life Sciences, Department of Molecular Life Sciences, Technical University of Munich, 85354 Freising, Germany
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22
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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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23
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Tomassetti D, Caracciolo S, Manciocco A, Chiarotti F, Vitale A, De Filippis B. Personality and lateralization in common marmosets (Callithrix jacchus). Behav Processes 2019; 167:103899. [DOI: 10.1016/j.beproc.2019.103899] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 06/28/2019] [Accepted: 07/02/2019] [Indexed: 12/27/2022]
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24
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Abstract
Drug consumption is driven by a drug's pharmacological effects, which are experienced as rewarding, and is influenced by genetic, developmental, and psychosocial factors that mediate drug accessibility, norms, and social support systems or lack thereof. The reinforcing effects of drugs mostly depend on dopamine signaling in the nucleus accumbens, and chronic drug exposure triggers glutamatergic-mediated neuroadaptations in dopamine striato-thalamo-cortical (predominantly in prefrontal cortical regions including orbitofrontal cortex and anterior cingulate cortex) and limbic pathways (amygdala and hippocampus) that, in vulnerable individuals, can result in addiction. In parallel, changes in the extended amygdala result in negative emotional states that perpetuate drug taking as an attempt to temporarily alleviate them. Counterintuitively, in the addicted person, the actual drug consumption is associated with an attenuated dopamine increase in brain reward regions, which might contribute to drug-taking behavior to compensate for the difference between the magnitude of the expected reward triggered by the conditioning to drug cues and the actual experience of it. Combined, these effects result in an enhanced motivation to "seek the drug" (energized by dopamine increases triggered by drug cues) and an impaired prefrontal top-down self-regulation that favors compulsive drug-taking against the backdrop of negative emotionality and an enhanced interoceptive awareness of "drug hunger." Treatment interventions intended to reverse these neuroadaptations show promise as therapeutic approaches for addiction.
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Affiliation(s)
- Nora D Volkow
- National Institute on Drug Abuse, National Institutes of Health, Bethesda, Maryland
| | - Michael Michaelides
- National Institute on Drug Abuse, National Institutes of Health, Bethesda, Maryland
| | - Ruben Baler
- National Institute on Drug Abuse, National Institutes of Health, Bethesda, Maryland
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25
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Karam CS, Jones SK, Javitch JA. Come Fly with Me: An overview of dopamine receptors in Drosophila melanogaster. Basic Clin Pharmacol Toxicol 2019; 126 Suppl 6:56-65. [PMID: 31219669 DOI: 10.1111/bcpt.13277] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 06/17/2019] [Indexed: 12/23/2022]
Abstract
Dopamine (DA) receptors play critical roles in a wide range of behaviours, including sensory processing, motor function, reward and arousal. As such, aberrant DA signalling is associated with numerous neurological and psychiatric disorders. Therefore, understanding the mechanisms by which DA neurotransmission drives intracellular signalling pathways that modulate behaviour can provide critical insights to guide the development of targeted therapeutics. Drosophila melanogaster has emerged as a powerful model with unique advantages to study the mechanisms underlying DA neurotransmission and associated behaviours in a controlled and systematic manner. Many regions in the fly brain innervated by dopaminergic neurons have been mapped and linked to specific behaviours, including associative learning and arousal. Here, we provide an overview of the homology between human and Drosophila dopaminergic systems and review the current literature on the pharmacology, molecular signalling mechanisms and behavioural outcome of DA receptor activation in the Drosophila brain.
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Affiliation(s)
- Caline S Karam
- Department of Psychiatry, Columbia University Vagelos College of Physicians and Surgeons, New York City, New York, USA.,Division of Molecular Therapeutics, New York State Psychiatric Institute, New York City, New York, USA
| | - Sandra K Jones
- Department of Psychiatry, Columbia University Vagelos College of Physicians and Surgeons, New York City, New York, USA.,Division of Molecular Therapeutics, New York State Psychiatric Institute, New York City, New York, USA
| | - Jonathan A Javitch
- Department of Psychiatry, Columbia University Vagelos College of Physicians and Surgeons, New York City, New York, USA.,Division of Molecular Therapeutics, New York State Psychiatric Institute, New York City, New York, USA.,Department of Pharmacology, Columbia University Vagelos College of Physicians and Surgeons, New York City, New York, USA
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26
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Petruccelli E, Kaun KR. Insights from intoxicated Drosophila. Alcohol 2019; 74:21-27. [PMID: 29980341 DOI: 10.1016/j.alcohol.2018.03.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 03/14/2018] [Accepted: 03/14/2018] [Indexed: 01/31/2023]
Abstract
Our understanding of alcohol use disorder (AUD), particularly alcohol's effects on the nervous system, has unquestionably benefited from the use of model systems such as Drosophila melanogaster. Here, we briefly introduce the use of flies in alcohol research, and highlight the genetic accessibility and neurobiological contribution that flies have made to our understanding of AUD. Future fly research offers unique opportunities for addressing unresolved questions in the alcohol field, such as the neuromolecular and circuit basis for cravings and alcohol-induced neuroimmune dysfunction. This review strongly advocates for interdisciplinary approaches and translational collaborations with the united goal of confronting the major health problems associated with alcohol abuse and addiction.
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27
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Friedman DA, Pilko A, Skowronska-Krawczyk D, Krasinska K, Parker JW, Hirsh J, Gordon DM. The Role of Dopamine in the Collective Regulation of Foraging in Harvester Ants. iScience 2018; 8:283-294. [PMID: 30270022 PMCID: PMC6205345 DOI: 10.1016/j.isci.2018.09.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 08/04/2018] [Accepted: 09/03/2018] [Indexed: 01/09/2023] Open
Abstract
Colonies of the red harvester ant (Pogonomyrmex barbatus) differ in how they regulate collective foraging activity in response to changes in humidity. We used transcriptomic, physiological, and pharmacological experiments to investigate the molecular basis of this ecologically important variation in collective behavior among colonies. RNA sequencing of forager brain tissue showed an association between colony foraging activity and differential expression of transcripts related to biogenic amine and neurohormonal metabolism and signaling. In field experiments, pharmacological increases in forager brain dopamine titer caused significant increases in foraging activity. Colonies that were naturally most sensitive to humidity were significantly more responsive to the stimulatory effect of exogenous dopamine. In addition, forager brain tissue significantly varied among colonies in biogenic amine content. Neurophysiological variation among colonies associated with individual forager sensitivity to humidity may reflect the heritable molecular variation on which natural selection acts to shape the collective regulation of foraging.
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Affiliation(s)
- Daniel A Friedman
- Department of Biology, Stanford University, Stanford, CA 94305, USA.
| | - Anna Pilko
- Department of Chemistry and Biochemistry and the Institute for Quantitative and Computational Biosciences (QCB), University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Dorota Skowronska-Krawczyk
- Shiley Eye Institute, Richard C. Atkinson Lab for Regenerative Ophthalmology, Department of Ophthalmology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Karolina Krasinska
- Stanford University Mass Spectrometry, Stanford University, Stanford, CA 94305, USA
| | - Jacqueline W Parker
- Department of Biology, University of Virginia, Charlottesville, Charlottesville, VA 22904, USA
| | - Jay Hirsh
- Department of Biology, University of Virginia, Charlottesville, Charlottesville, VA 22904, USA
| | - Deborah M Gordon
- Department of Biology, Stanford University, Stanford, CA 94305, USA
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28
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Petruccelli E, Feyder M, Ledru N, Jaques Y, Anderson E, Kaun KR. Alcohol Activates Scabrous-Notch to Influence Associated Memories. Neuron 2018; 100:1209-1223.e4. [PMID: 30482693 DOI: 10.1016/j.neuron.2018.10.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 08/17/2018] [Accepted: 10/02/2018] [Indexed: 12/17/2022]
Abstract
Drugs of abuse, like alcohol, modulate gene expression in reward circuits and consequently alter behavior. However, the in vivo cellular mechanisms through which alcohol induces lasting transcriptional changes are unclear. We show that Drosophila Notch/Su(H) signaling and the secreted fibrinogen-related protein Scabrous in mushroom body (MB) memory circuitry are important for the enduring preference of cues associated with alcohol's rewarding properties. Alcohol exposure affects Notch responsivity in the adult MB and alters Su(H) targeting at the dopamine-2-like receptor (Dop2R). Alcohol cue training also caused lasting changes to the MB nuclear transcriptome, including changes in the alternative splicing of Dop2R and newly implicated transcripts like Stat92E. Together, our data suggest that alcohol-induced activation of the highly conserved Notch pathway and accompanying transcriptional responses in memory circuitry contribute to addiction. Ultimately, this provides mechanistic insight into the etiology and pathophysiology of alcohol use disorder.
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Affiliation(s)
- Emily Petruccelli
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Michael Feyder
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Nicolas Ledru
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Yanabah Jaques
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Edward Anderson
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Karla R Kaun
- Department of Neuroscience, Brown University, Providence, RI 02912, USA.
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29
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Srinivasan S, Greenspan RJ, Stevens CF, Grover D. Deep(er) Learning. J Neurosci 2018; 38:7365-7374. [PMID: 30006366 PMCID: PMC6596136 DOI: 10.1523/jneurosci.0153-18.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/30/2018] [Accepted: 07/05/2018] [Indexed: 12/30/2022] Open
Abstract
Animals successfully thrive in noisy environments with finite resources. The necessity to function with resource constraints has led evolution to design animal brains (and bodies) to be optimal in their use of computational power while being adaptable to their environmental niche. A key process undergirding this ability to adapt is the process of learning. Although a complete characterization of the neural basis of learning remains ongoing, scientists for nearly a century have used the brain as inspiration to design artificial neural networks capable of learning, a case in point being deep learning. In this viewpoint, we advocate that deep learning can be further enhanced by incorporating and tightly integrating five fundamental principles of neural circuit design and function: optimizing the system to environmental need and making it robust to environmental noise, customizing learning to context, modularizing the system, learning without supervision, and learning using reinforcement strategies. We illustrate how animals integrate these learning principles using the fruit fly olfactory learning circuit, one of nature's best-characterized and highly optimized schemes for learning. Incorporating these principles may not just improve deep learning but also expose common computational constraints. With judicious use, deep learning can become yet another effective tool to understand how and why brains are designed the way they are.
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Affiliation(s)
- Shyam Srinivasan
- Kavli Institute for Brain and Mind, University of California-San Diego, La Jolla, California 92093
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037
| | - Ralph J Greenspan
- Kavli Institute for Brain and Mind, University of California-San Diego, La Jolla, California 92093
- Division of Biological Sciences, University of California-San Diego, La Jolla, California 92093, and
- Department of Cognitive Science, University of California-San Diego, La Jolla, California 92093
| | - Charles F Stevens
- Kavli Institute for Brain and Mind, University of California-San Diego, La Jolla, California 92093,
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037
| | - Dhruv Grover
- Kavli Institute for Brain and Mind, University of California-San Diego, La Jolla, California 92093,
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30
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Early deprivation disruption of associative learning is a developmental pathway to depression and social problems. Nat Commun 2018; 9:2216. [PMID: 29880851 PMCID: PMC5992195 DOI: 10.1038/s41467-018-04381-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 04/23/2018] [Indexed: 12/20/2022] Open
Abstract
Exposure to psychosocial deprivation is associated with elevations in numerous forms of impairment throughout the life-course. Disruptions in associative learning may be a key mechanism through which adversity, particularly psychosocial deprivation, increases risk for impairment. Existing data consistent with this claim come entirely from correlational studies. Here, we present the first experimental evidence relating psychosocial deprivation and disruptions in multiple forms of associative learning. Using data from the Bucharest Early Intervention Project, we demonstrate that randomized placement into a family caregiving environment during the infant/toddler period as compared to prolonged institutional care normalizes two forms of associative learning in early adolescence: reward responsivity and implicit motor learning. These forms of associative learning significantly mediate the effect of institutional rearing on depressive symptoms and peer relationships. In sum, we provide evidence for a novel pathway linking early experience to psychopathology and peer relationships through basic associative learning mechanisms. Early childhood deprivation such as institutionalization can greatly affect early development. Here, the authors study children who were raised in institutions but later randomly placed in foster care vs. not, to understand how early-life deprivation affects associative learning in adolescence.
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31
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Ryvkin J, Bentzur A, Zer-Krispil S, Shohat-Ophir G. Mechanisms Underlying the Risk to Develop Drug Addiction, Insights From Studies in Drosophila melanogaster. Front Physiol 2018; 9:327. [PMID: 29740329 PMCID: PMC5928757 DOI: 10.3389/fphys.2018.00327] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Accepted: 03/15/2018] [Indexed: 12/21/2022] Open
Abstract
The ability to adapt to environmental changes is an essential feature of biological systems, achieved in animals by a coordinated crosstalk between neuronal and hormonal programs that allow rapid and integrated organismal responses. Reward systems play a key role in mediating this adaptation by reinforcing behaviors that enhance immediate survival, such as eating or drinking, or those that ensure long-term survival, such as sexual behavior or caring for offspring. Drugs of abuse co-opt neuronal and molecular pathways that mediate natural rewards, which under certain circumstances can lead to addiction. Many factors can contribute to the transition from drug use to drug addiction, highlighting the need to discover mechanisms underlying the progression from initial drug use to drug addiction. Since similar responses to natural and drug rewards are present in very different animals, it is likely that the central systems that process reward stimuli originated early in evolution, and that common ancient biological principles and genes are involved in these processes. Thus, the neurobiology of natural and drug rewards can be studied using simpler model organisms that have their systems stripped of some of the immense complexity that exists in mammalian brains. In this paper we review studies in Drosophila melanogaster that model different aspects of natural and drug rewards, with an emphasis on how motivational states shape the value of the rewarding experience, as an entry point to understanding the mechanisms that contribute to the vulnerability of drug addiction.
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Affiliation(s)
- Julia Ryvkin
- The Mina & Everard Goodman Faculty of Life Sciences and The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
| | - Assa Bentzur
- The Mina & Everard Goodman Faculty of Life Sciences and The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
| | - Shir Zer-Krispil
- The Mina & Everard Goodman Faculty of Life Sciences and The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
| | - Galit Shohat-Ophir
- The Mina & Everard Goodman Faculty of Life Sciences and The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
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Lowenstein EG, Velazquez-Ulloa NA. A Fly's Eye View of Natural and Drug Reward. Front Physiol 2018; 9:407. [PMID: 29720947 PMCID: PMC5915475 DOI: 10.3389/fphys.2018.00407] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 04/04/2018] [Indexed: 12/18/2022] Open
Abstract
Animals encounter multiple stimuli each day. Some of these stimuli are innately appetitive or aversive, while others are assigned valence based on experience. Drugs like ethanol can elicit aversion in the short term and attraction in the long term. The reward system encodes the predictive value for different stimuli, mediating anticipation for attractive or punishing stimuli and driving animal behavior to approach or avoid conditioned stimuli. The neurochemistry and neurocircuitry of the reward system is partly evolutionarily conserved. In both vertebrates and invertebrates, including Drosophila melanogaster, dopamine is at the center of a network of neurotransmitters and neuromodulators acting in concert to encode rewards. Behavioral assays in D. melanogaster have become increasingly sophisticated, allowing more direct comparison with mammalian research. Moreover, recent evidence has established the functional modularity of the reward neural circuits in Drosophila. This functional modularity resembles the organization of reward circuits in mammals. The powerful genetic and molecular tools for D. melanogaster allow characterization and manipulation at the single-cell level. These tools are being used to construct a detailed map of the neural circuits mediating specific rewarding stimuli and have allowed for the identification of multiple genes and molecular pathways that mediate the effects of reinforcing stimuli, including their rewarding effects. This report provides an overview of the research on natural and drug reward in D. melanogaster, including natural rewards such as sugar and other food nutrients, and drug rewards including ethanol, cocaine, amphetamine, methamphetamine, and nicotine. We focused mainly on the known genetic and neural mechanisms underlying appetitive reward for sugar and reward for ethanol. We also include genes, molecular pathways, and neural circuits that have been identified using assays that test the palatability of the rewarding stimulus, the preference for the rewarding stimulus, or other effects of the stimulus that indicate how it can modify behavior. Commonalities between mechanisms of natural and drug reward are highlighted and future directions are presented, putting forward questions best suited for research using D. melanogaster as a model organism.
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Affiliation(s)
- Eve G Lowenstein
- Department of Biology, Lewis & Clark College, Portland, OR, United States
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Tauber JM, Brown EB, Li Y, Yurgel ME, Masek P, Keene AC. A subset of sweet-sensing neurons identified by IR56d are necessary and sufficient for fatty acid taste. PLoS Genet 2017; 13:e1007059. [PMID: 29121639 PMCID: PMC5697886 DOI: 10.1371/journal.pgen.1007059] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 11/21/2017] [Accepted: 10/08/2017] [Indexed: 01/10/2023] Open
Abstract
Fat represents a calorically potent food source that yields approximately twice the amount of energy as carbohydrates or proteins per unit of mass. The highly palatable taste of free fatty acids (FAs), one of the building blocks of fat, promotes food consumption, activates reward circuitry, and is thought to contribute to hedonic feeding underlying many metabolism-related disorders. Despite a role in the etiology of metabolic diseases, little is known about how dietary fats are detected by the gustatory system to promote feeding. Previously, we showed that a broad population of sugar-sensing taste neurons expressing Gustatory Receptor 64f (Gr64f) is required for reflexive feeding responses to both FAs and sugars. Here, we report a genetic silencing screen to identify specific populations of taste neurons that mediate fatty acid (FA) taste. We find neurons identified by expression of Ionotropic Receptor 56d (IR56d) are necessary and sufficient for reflexive feeding response to FAs. Functional imaging reveals that IR56d-expressing neurons are responsive to short- and medium-chain FAs. Silencing IR56d neurons selectively abolishes FA taste, and their activation is sufficient to drive feeding responses. Analysis of co-expression with Gr64f identifies two subpopulations of IR56d-expressing neurons. While physiological imaging reveals that both populations are responsive to FAs, IR56d/Gr64f neurons are activated by medium-chain FAs and are sufficient for reflexive feeding response to FAs. Moreover, flies can discriminate between sugar and FAs in an aversive taste memory assay, indicating that FA taste is a unique modality in Drosophila. Taken together, these findings localize FA taste within the Drosophila gustatory center and provide an opportunity to investigate discrimination between different categories of appetitive tastants. Fat represents a calorically potent food source that yields approximately twice the amount of energy as carbohydrates or proteins per unit of mass. Dietary lipids are comprised of both triacylglycerides and FAs, and growing evidence suggests that it is the free FAs that are detected by the gustatory system. The highly palatable taste of FAs promotes food consumption, activates reward centers in mammals, and is thought to contribute to hedonic feeding that underlies many metabolism-related disorders. Despite a role in the etiology of metabolic diseases, little is known about how dietary fats are detected by the gustatory system to promote feeding. We have identified a subset of sugar-sensing neurons in the fly that also responds to medium-chain FAs and are necessary and sufficient for behavioral response to FAs. Further, we find that despite being sensed by shared neuronal populations, flies can differentiate between the taste of sugar and FAs, fortifying the notion that FAs and sugar represent distinct taste modalities in flies.
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Affiliation(s)
- John M. Tauber
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL, United States of America
| | - Elizabeth B. Brown
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL, United States of America
| | - Yuanyuan Li
- Department of Biological Sciences, Binghamton University, Binghamton, NY, United States of America
| | - Maria E. Yurgel
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL, United States of America
| | - Pavel Masek
- Department of Biological Sciences, Binghamton University, Binghamton, NY, United States of America
| | - Alex C. Keene
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL, United States of America
- * E-mail:
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Dissection of the Drosophila neuropeptide F circuit using a high-throughput two-choice assay. Proc Natl Acad Sci U S A 2017; 114:E8091-E8099. [PMID: 28874527 DOI: 10.1073/pnas.1710552114] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
In their classic experiments, Olds and Milner showed that rats learn to lever press to receive an electric stimulus in specific brain regions. This led to the identification of mammalian reward centers. Our interest in defining the neuronal substrates of reward perception in the fruit fly Drosophila melanogaster prompted us to develop a simpler experimental approach wherein flies could implement behavior that induces self-stimulation of specific neurons in their brains. The high-throughput assay employs optogenetic activation of neurons when the fly occupies a specific area of a behavioral chamber, and the flies' preferential occupation of this area reflects their choosing to experience optogenetic stimulation. Flies in which neuropeptide F (NPF) neurons are activated display preference for the illuminated side of the chamber. We show that optogenetic activation of NPF neuron is rewarding in olfactory conditioning experiments and that the preference for NPF neuron activation is dependent on NPF signaling. Finally, we identify a small subset of NPF-expressing neurons located in the dorsomedial posterior brain that are sufficient to elicit preference in our assay. This assay provides the means for carrying out unbiased screens to map reward neurons in flies.
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Dopaminergic rules of engagement for memory in Drosophila. Curr Opin Neurobiol 2017; 43:56-62. [PMID: 28088703 DOI: 10.1016/j.conb.2016.12.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 12/20/2016] [Accepted: 12/26/2016] [Indexed: 11/21/2022]
Abstract
Dopamine is associated with a variety of conserved responses across species including locomotion, sleep, food consumption, aggression, courtship, addiction and several forms of appetitive and aversive memory. Historically, dopamine has been most prominently associated with dynamics underlying reward, punishment, or salience. Recent emerging evidence from Drosophila supports a role in all of these functions, as well as additional roles in the interplay between external sensation and internal states and forgetting of the very memories dopamine helped encode. We discuss how cell-specific resolution and manipulation are elucidating the rules of dopamine's involvement in encoding valence and memory.
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Gilpin NW, Weiner JL. Neurobiology of comorbid post-traumatic stress disorder and alcohol-use disorder. GENES BRAIN AND BEHAVIOR 2016; 16:15-43. [PMID: 27749004 DOI: 10.1111/gbb.12349] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 10/03/2016] [Accepted: 10/07/2016] [Indexed: 12/12/2022]
Abstract
Post-traumatic stress disorder (PTSD) and alcohol-use disorder (AUD) are highly comorbid in humans. Although we have some understanding of the structural and functional brain changes that define each of these disorders, and how those changes contribute to the behavioral symptoms that define them, little is known about the neurobiology of comorbid PTSD and AUD, which may be due in part to a scarcity of adequate animal models for examining this research question. The goal of this review is to summarize the current state-of-the-science on comorbid PTSD and AUD. We summarize epidemiological data documenting the prevalence of this comorbidity, review what is known about the potential neurobiological basis for the frequent co-occurrence of PTSD and AUD and discuss successes and failures of past and current treatment strategies. We also review animal models that aim to examine comorbid PTSD and AUD, highlighting where the models parallel the human condition, and we discuss the strengths and weaknesses of each model. We conclude by discussing key gaps in our knowledge and strategies for addressing them: in particular, we (1) highlight the need for better animal models of the comorbid condition and better clinical trial design, (2) emphasize the need for examination of subpopulation effects and individual differences and (3) urge cross-talk between basic and clinical researchers that is reflected in collaborative work with forward and reverse translational impact.
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Affiliation(s)
- N W Gilpin
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, LA.,Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA
| | - J L Weiner
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
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