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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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2
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Ranson DC, Ayoub SS, Corcoran O, Casalotti SO. Pharmacological targeting of the GABA B receptor alters Drosophila's behavioural responses to alcohol. Addict Biol 2020; 25:e12725. [PMID: 30761704 PMCID: PMC7050513 DOI: 10.1111/adb.12725] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 01/14/2019] [Accepted: 01/17/2019] [Indexed: 01/15/2023]
Abstract
When exposed to ethanol, Drosophila melanogaster display a variety of addiction-like behaviours similar to those observed in mammals. Sensitivity to ethanol can be quantified by measuring the time at which 50% of the flies are sedated by ethanol exposure (ST50); an increase of ST50 following multiple ethanol exposures is widely interpreted as development of tolerance to ethanol. Sensitivity and tolerance to ethanol were measured after administration of the gamma-aminobutyric acid receptor B (GABAB ) agonist (SKF 97541) and antagonist (CGP 54626), when compared with flies treated with ethanol alone. Dose-dependent increases and decreases in sensitivity to ethanol were observed for both the agonist and antagonist respectively. Tolerance was recorded in the presence of GABAB drugs, but the rate of tolerance development was increased by SKF 97451 and unaltered in presence of CGP 54626. This indicates that the GABAB receptor contributes to both the sensitivity to ethanol and mechanisms by which tolerance develops. The data also reinforce the usefulness of Drosophila as a model for identifying the molecular components of addictive behaviours and for testing drugs that could potentially be used for the treatment of alcohol use disorder (AUD).
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Affiliation(s)
| | - Samir S. Ayoub
- Medicines Research GroupUniversity of East London London UK
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3
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Ramirez-Roman ME, Billini CE, Ghezzi A. Epigenetic Mechanisms of Alcohol Neuroadaptation: Insights from Drosophila. J Exp Neurosci 2018; 12:1179069518779809. [PMID: 29899666 PMCID: PMC5990879 DOI: 10.1177/1179069518779809] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 05/09/2018] [Indexed: 12/28/2022] Open
Abstract
Alcohol addiction is a serious condition perpetuated by enduring physiological and behavioral adaptations. An important component of these adaptations is the long-term rearrangement of neuronal gene expression in the brain of the addicted individual. Epigenetic histone modifications have recently surfaced as important modulators of the transcriptional adaptation to alcohol as these are thought to represent a form of transcriptional memory that is directly imprinted on the chromosome. Some histone modifications affect transcription by modulating the accessibility of the underlying DNA, whereas others have been proposed to serve as marks read by transcription factors as a "histone code" that helps to specify the expression level of a gene. Although the effects of some epigenetic modifications on the transcriptional activity of genes are well known, the mechanisms by which alcohol consumption produces this rearrangement and leads to lasting changes in behavior remain unresolved. Recent advances using the Drosophila model system have started to unravel the epigenetic modulators underlying functional alcohol neuroadaptations. In this review, we discuss the role of 3 different histone modification systems in Drosophila, which have a direct impact on key alcohol neuroadaptations associated with the addictive process. These systems involve the histone deacetylase Sirt1, the histone acetyltransferase CREB-binding protein (CBP), and a subset of the Drosophila JmjC-Domain histone demethylase family.
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Affiliation(s)
| | - Carlos E Billini
- Department of Biology, University of Puerto Rico–Rio Piedras, San Juan, PR, USA
| | - Alfredo Ghezzi
- Department of Biology, University of Puerto Rico–Rio Piedras, San Juan, PR, USA
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4
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De Nobrega AK, Lyons LC. Drosophila: An Emergent Model for Delineating Interactions between the Circadian Clock and Drugs of Abuse. Neural Plast 2017; 2017:4723836. [PMID: 29391952 PMCID: PMC5748135 DOI: 10.1155/2017/4723836] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 08/13/2017] [Indexed: 01/12/2023] Open
Abstract
Endogenous circadian oscillators orchestrate rhythms at the cellular, physiological, and behavioral levels across species to coordinate activity, for example, sleep/wake cycles, metabolism, and learning and memory, with predictable environmental cycles. The 21st century has seen a dramatic rise in the incidence of circadian and sleep disorders with globalization, technological advances, and the use of personal electronics. The circadian clock modulates alcohol- and drug-induced behaviors with circadian misalignment contributing to increased substance use and abuse. Invertebrate models, such as Drosophila melanogaster, have proven invaluable for the identification of genetic and molecular mechanisms underlying highly conserved processes including the circadian clock, drug tolerance, and reward systems. In this review, we highlight the contributions of Drosophila as a model system for understanding the bidirectional interactions between the circadian system and the drugs of abuse, alcohol and cocaine, and illustrate the highly conserved nature of these interactions between Drosophila and mammalian systems. Research in Drosophila provides mechanistic insights into the corresponding behaviors in higher organisms and can be used as a guide for targeted inquiries in mammals.
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Affiliation(s)
- Aliza K. De Nobrega
- Department of Biological Science, Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
| | - Lisa C. Lyons
- Department of Biological Science, Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
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5
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FLIC: high-throughput, continuous analysis of feeding behaviors in Drosophila. PLoS One 2014; 9:e101107. [PMID: 24978054 PMCID: PMC4076220 DOI: 10.1371/journal.pone.0101107] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 05/30/2014] [Indexed: 12/01/2022] Open
Abstract
We present a complete hardware and software system for collecting and quantifying continuous measures of feeding behaviors in the fruit fly, Drosophila melanogaster. The FLIC (Fly Liquid-Food Interaction Counter) detects analog electronic signals as brief as 50 µs that occur when a fly makes physical contact with liquid food. Signal characteristics effectively distinguish between different types of behaviors, such as feeding and tasting events. The FLIC system performs as well or better than popular methods for simple assays, and it provides an unprecedented opportunity to study novel components of feeding behavior, such as time-dependent changes in food preference and individual levels of motivation and hunger. Furthermore, FLIC experiments can persist indefinitely without disturbance, and we highlight this ability by establishing a detailed picture of circadian feeding behaviors in the fly. We believe that the FLIC system will work hand-in-hand with modern molecular techniques to facilitate mechanistic studies of feeding behaviors in Drosophila using modern, high-throughput technologies.
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Krishnan HR, Sakharkar AJ, Teppen TL, Berkel TDM, Pandey SC. The epigenetic landscape of alcoholism. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 115:75-116. [PMID: 25131543 DOI: 10.1016/b978-0-12-801311-3.00003-2] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Alcoholism is a complex psychiatric disorder that has a multifactorial etiology. Epigenetic mechanisms are uniquely capable of accounting for the multifactorial nature of the disease in that they are highly stable and are affected by environmental factors, including alcohol itself. Chromatin remodeling causes changes in gene expression in specific brain regions contributing to the endophenotypes of alcoholism such as tolerance and dependence. The epigenetic mechanisms that regulate changes in gene expression observed in addictive behaviors respond not only to alcohol exposure but also to comorbid psychopathology such as the presence of anxiety and stress. This review summarizes recent developments in epigenetic research that may play a role in alcoholism. We propose that pharmacologically manipulating epigenetic targets, as demonstrated in various preclinical models, hold great therapeutic potential in the treatment and prevention of alcoholism.
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Affiliation(s)
- Harish R Krishnan
- Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, USA; Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, USA
| | - Amul J Sakharkar
- Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, USA; Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, USA
| | - Tara L Teppen
- Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, USA; Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, USA
| | - Tiffani D M Berkel
- Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, USA; Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, USA
| | - Subhash C Pandey
- Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, USA; Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, USA; Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois, USA.
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Ghezzi A, Krishnan HR, Lew L, Prado FJ, Ong DS, Atkinson NS. Alcohol-induced histone acetylation reveals a gene network involved in alcohol tolerance. PLoS Genet 2013; 9:e1003986. [PMID: 24348266 PMCID: PMC3861128 DOI: 10.1371/journal.pgen.1003986] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 10/14/2013] [Indexed: 12/19/2022] Open
Abstract
Sustained or repeated exposure to sedating drugs, such as alcohol, triggers homeostatic adaptations in the brain that lead to the development of drug tolerance and dependence. These adaptations involve long-term changes in the transcription of drug-responsive genes as well as an epigenetic restructuring of chromosomal regions that is thought to signal and maintain the altered transcriptional state. Alcohol-induced epigenetic changes have been shown to be important in the long-term adaptation that leads to alcohol tolerance and dependence endophenotypes. A major constraint impeding progress is that alcohol produces a surfeit of changes in gene expression, most of which may not make any meaningful contribution to the ethanol response under study. Here we used a novel genomic epigenetic approach to find genes relevant for functional alcohol tolerance by exploiting the commonalities of two chemically distinct alcohols. In Drosophila melanogaster, ethanol and benzyl alcohol induce mutual cross-tolerance, indicating that they share a common mechanism for producing tolerance. We surveyed the genome-wide changes in histone acetylation that occur in response to these drugs. Each drug induces modifications in a large number of genes. The genes that respond similarly to either treatment, however, represent a subgroup enriched for genes important for the common tolerance response. Genes were functionally tested for behavioral tolerance to the sedative effects of ethanol and benzyl alcohol using mutant and inducible RNAi stocks. We identified a network of genes that are essential for the development of tolerance to sedation by alcohol.
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Affiliation(s)
- Alfredo Ghezzi
- Section of Neurobiology and Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, United States of America
- * E-mail: (AG); (NSA)
| | - Harish R. Krishnan
- Section of Neurobiology and Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, United States of America
| | - Linda Lew
- Section of Neurobiology and Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, United States of America
| | - Francisco J. Prado
- Section of Neurobiology and Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, United States of America
| | - Darryl S. Ong
- Section of Neurobiology and Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, United States of America
| | - Nigel S. Atkinson
- Section of Neurobiology and Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, United States of America
- * E-mail: (AG); (NSA)
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Pohl JB, Ghezzi A, Lew LK, Robles RB, Cormack L, Atkinson NS. Circadian genes differentially affect tolerance to ethanol in Drosophila. Alcohol Clin Exp Res 2013; 37:1862-71. [PMID: 23808628 PMCID: PMC4861224 DOI: 10.1111/acer.12173] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 03/29/2013] [Indexed: 11/28/2022]
Abstract
BACKGROUND There is a strong relationship between circadian rhythms and ethanol (EtOH) responses. EtOH consumption has been shown to disrupt physiological and behavioral circadian rhythms in mammals (Alcohol Clin Exp Res 2005b, 29, 1550). The Drosophila central circadian pacemaker is composed of proteins encoded by the per, tim, cyc, and Clk genes. Using Drosophila mutant analysis, we asked whether these central components of the circadian clock make the equivalent contribution toward EtOH tolerance and whether rhythmicity itself is necessary for tolerance. METHODS We tested flies carrying mutations in core clock genes for the capacity to acquire EtOH tolerance. Tolerance was assayed by comparing the sedation curves of populations during their first and second sedation. Animals that had acquired tolerance sedated more slowly. Movement was also monitored as the flies breathe the EtOH vapor to determine if other facets of the EtOH response were affected by the mutations. Gas chromatography was used to measure internal EtOH concentration. Constant light was used to nongenetically destabilize the PER and TIM proteins. RESULTS A group of circadian mutations, all of which eliminate circadian rhythms, do not disrupt tolerance identically. Mutations in per, tim, and cyc completely block tolerance. However, a mutation in Clk does not interfere with tolerance. Constant light also disrupts the capacity to acquire tolerance. These lines did not differ in EtOH absorption. CONCLUSIONS Mutations affecting different parts of the intracellular circadian clock can block the capacity to acquire rapid EtOH tolerance. However, the role of circadian genes in EtOH tolerance is independent of their role in producing circadian rhythmicity. The interference in the capacity to acquire EtOH tolerance by some circadian mutations is not merely a downstream effect of a nonfunctional circadian clock; instead, these circadian genes play an independent role in EtOH tolerance.
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Affiliation(s)
- Jascha B. Pohl
- The Waggoner Center for Alcohol and Addiction Research, Section of Neurobiology, The University of Texas at Austin, 1 University Station C0920, Austin, Texas, 78712 USA
| | - Alfredo Ghezzi
- The Waggoner Center for Alcohol and Addiction Research, Section of Neurobiology, The University of Texas at Austin, 1 University Station C0920, Austin, Texas, 78712 USA
| | - Linda K. Lew
- The Waggoner Center for Alcohol and Addiction Research, Section of Neurobiology, The University of Texas at Austin, 1 University Station C0920, Austin, Texas, 78712 USA
| | - Roseanna B. Robles
- The Waggoner Center for Alcohol and Addiction Research, Section of Neurobiology, The University of Texas at Austin, 1 University Station C0920, Austin, Texas, 78712 USA
| | - Lawrence Cormack
- Department of Psychology & Section of Neurobiology, The University of Texas at Austin, Texas 78712
| | - Nigel S. Atkinson
- The Waggoner Center for Alcohol and Addiction Research, Section of Neurobiology, The University of Texas at Austin, 1 University Station C0920, Austin, Texas, 78712 USA
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Dillon J, Andrianakis I, Mould R, Ient B, Liu W, James C, O'Connor V, Holden-Dye L. Distinct molecular targets including SLO-1 and gap junctions are engaged across a continuum of ethanol concentrations in Caenorhabditis elegans. FASEB J 2013; 27:4266-78. [PMID: 23882127 DOI: 10.1096/fj.11-189340] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Ethanol (alcohol) interacts with diverse molecular effectors across a range of concentrations in the brain, eliciting intoxication through to sedation. Invertebrate models including the nematode worm Caenorhabditis elegans have been deployed for molecular genetic studies to inform on key components of these alcohol signaling pathways. C. elegans studies have typically employed external dosing with high (>250 mM) ethanol concentrations: A careful analysis of responses to low concentrations is lacking. Using the C. elegans pharyngeal system as a paradigm, we report a previously uncharacterized continuum of cellular and behavioral responses to ethanol from low (10 mM) to high (300 mM) concentrations. The complexity of these responses indicates that the pleiotropic action of ethanol observed in mammalian brain is conserved in this invertebrate model. We investigated two candidate ethanol effectors, the calcium-activated K(+) channel SLO-1 and gap junctions, and show that they contribute to, but are not sole determinants of, the low- and high-concentration effects, respectively. Notably, this study shows cellular and whole organismal behavioral responses to ethanol in C. elegans that directly equate to intoxicating through to supralethal blood alcohol concentrations in humans and provides an important benchmark for interpretation of paradigms that seek to inform on human alcohol use disorders.
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Affiliation(s)
- James Dillon
- 1Current address: Institute of Digital Healthcare, Warwick Manufacturing Group, University of Warwick, Coventry CV4 7AL, UK
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Robinson BG, Khurana S, Atkinson NS. Drosophila larvae as a model to study physiological alcohol dependence. Commun Integr Biol 2013; 6:e23501. [PMID: 23750304 PMCID: PMC3609852 DOI: 10.4161/cib.23501] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Alcohol addiction is a disease that includes a diverse set of phenotypes. Functional alcohol tolerance is an adaptation to the effects of alcohol that restores neuronal homeostatic balance while the drug is present. When the drug is suddenly withheld, these adaptations unbalance the nervous system and are thought to be the origin of some withdrawal symptoms. Withdrawal symptoms, which can be a motivating factor for alcoholics to relapse, are taken as evidence of physiological ethanol dependence. Both tolerance and withdrawal symptoms are diagnostic criteria for alcoholism. Recent studies have demonstrated that the larvae of Drosophila show conserved alcohol tolerance and withdrawal phenotypes indicating that Drosophila genetics can now be used in studying this endophenotype of alcohol addiction.
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Affiliation(s)
- Brooks G Robinson
- Section of Neurobiology and Waggoner Center for Alcohol and Addiction Research; The University of Texas at Austin; Austin, TX USA
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11
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Cavaliere S, Gillespie JM, Hodge JJL. KCNQ channels show conserved ethanol block and function in ethanol behaviour. PLoS One 2012; 7:e50279. [PMID: 23209695 PMCID: PMC3510227 DOI: 10.1371/journal.pone.0050279] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 10/23/2012] [Indexed: 01/01/2023] Open
Abstract
In humans, KCNQ2/3 channels form an M-current that regulates neuronal excitability, with mutations in these channels causing benign neonatal familial convulsions. The M-current is important in mechanisms of neural plasticity underlying associative memory and in the response to ethanol, with KCNQ controlling the release of dopamine after ethanol exposure. We show that dKCNQ is broadly expressed in the nervous system, with targeted reduction in neuronal KCNQ increasing neural excitability and KCNQ overexpression decreasing excitability and calcium signalling, consistent with KCNQ regulating the resting membrane potential and neural release as in mammalian neurons. We show that the single KCNQ channel in Drosophila (dKCNQ) has similar electrophysiological properties to neuronal KCNQ2/3, including conserved acute sensitivity to ethanol block, with the fly channel (IC(50) = 19.8 mM) being more sensitive than its mammalian ortholog (IC(50) = 42.1 mM). This suggests that the role of KCNQ in alcohol behaviour can be determined for the first time by using Drosophila. We present evidence that loss of KCNQ function in Drosophila increased sensitivity and tolerance to the sedative effects of ethanol. Acute activation of dopaminergic neurons by heat-activated TRP channel or KCNQ-RNAi expression produced ethanol hypersensitivity, suggesting that both act via a common mechanism involving membrane depolarisation and increased dopamine signalling leading to ethanol sedation.
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Affiliation(s)
- Sonia Cavaliere
- School of Physiology and Pharmacology, University of Bristol, Bristol, Avon, United Kingdom
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12
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Robinson BG, Khurana S, Pohl JB, Li WK, Ghezzi A, Cady AM, Najjar K, Hatch MM, Shah RR, Bhat A, Hariri O, Haroun KB, Young MC, Fife K, Hooten J, Tran T, Goan D, Desai F, Husain F, Godinez RM, Sun JC, Corpuz J, Moran J, Zhong AC, Chen WY, Atkinson NS. A low concentration of ethanol impairs learning but not motor and sensory behavior in Drosophila larvae. PLoS One 2012; 7:e37394. [PMID: 22624024 PMCID: PMC3356251 DOI: 10.1371/journal.pone.0037394] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 04/22/2012] [Indexed: 11/18/2022] Open
Abstract
Drosophila melanogaster has proven to be a useful model system for the genetic analysis of ethanol-associated behaviors. However, past studies have focused on the response of the adult fly to large, and often sedating, doses of ethanol. The pharmacological effects of low and moderate quantities of ethanol have remained understudied. In this study, we tested the acute effects of low doses of ethanol (∼7 mM internal concentration) on Drosophila larvae. While ethanol did not affect locomotion or the response to an odorant, we observed that ethanol impaired associative olfactory learning when the heat shock unconditioned stimulus (US) intensity was low but not when the heat shock US intensity was high. We determined that the reduction in learning at low US intensity was not a result of ethanol anesthesia since ethanol-treated larvae responded to the heat shock in the same manner as untreated animals. Instead, low doses of ethanol likely impair the neuronal plasticity that underlies olfactory associative learning. This impairment in learning was reversible indicating that exposure to low doses of ethanol does not leave any long lasting behavioral or physiological effects.
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Affiliation(s)
- Brooks G. Robinson
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Sukant Khurana
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Jascha B. Pohl
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Wen-ke Li
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Alfredo Ghezzi
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Amanda M. Cady
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Kristina Najjar
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Michael M. Hatch
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Ruchita R. Shah
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Amar Bhat
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Omar Hariri
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Kareem B. Haroun
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Melvin C. Young
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Kathryn Fife
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Jeff Hooten
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Tuan Tran
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Daniel Goan
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Foram Desai
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Farhan Husain
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Ryan M. Godinez
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Jeffrey C. Sun
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Jonathan Corpuz
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Jacxelyn Moran
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Allen C. Zhong
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - William Y. Chen
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
| | - Nigel S. Atkinson
- Section of Neurobiology, Institute for Neuroscience, The University of Texas at Austin, Austin, Texas, United States of America
- * E-mail:
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13
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Pohl JB, Baldwin BA, Dinh BL, Rahman P, Smerek D, Prado FJ, Sherazee N, Atkinson NS. Ethanol preference in Drosophila melanogaster is driven by its caloric value. Alcohol Clin Exp Res 2012; 36:1903-12. [PMID: 22551215 DOI: 10.1111/j.1530-0277.2012.01817.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 02/15/2012] [Indexed: 12/01/2022]
Abstract
BACKGROUND Perhaps the most difficult thing to ascertain concerning the behavior of another animal is its motivation. The motivation underlying the preference of Drosophila melanogaster for ethanol (EtOH)-rich food has long been ascribed to its value as a food. A recently introduced idea is that, as in humans, the pharmacological effects of EtOH also motivate the fly to choose EtOH-rich food over nonalcoholic food. METHODS Flies are given a choice between pipets that contain liquid food and liquid food supplemented with EtOH. In some experiments, carbohydrates are added to the non-EtOH-containing food to balance the calories for EtOH. RESULTS We confirm that D. melanogaster indeed prefer food that is supplemented with EtOH. However, if the alternative food choice is isocaloric, D. melanogaster usually do not show any preference for a 10% EtOH solution. Even after EtOH preference has been established, it can be completely reversed if the alternative food is calorically supplemented. This occurs even when the carbohydrate solution used to balance calories is not gustatorily attractive. Furthermore, if the alternative food contains more calories than the EtOH food, the flies will prefer the non-EtOH food. We go on to show that during the preference assay that EtOH in the fly does not exceed 4 mM, which in mammals is a nonintoxicating dose. CONCLUSIONS We conclude that preference for EtOH in this assay arises not from the pharmacological effects of EtOH but rather because of its nutritive value.
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Affiliation(s)
- Jascha B Pohl
- Waggoner Center for Alcohol and Addiction Research , Section of Neurobiology, The University of Texas at Austin, TX 78712, USA
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Kaun KR, Devineni AV, Heberlein U. Drosophila melanogaster as a model to study drug addiction. Hum Genet 2012; 131:959-75. [PMID: 22350798 PMCID: PMC3351628 DOI: 10.1007/s00439-012-1146-6] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 02/04/2012] [Indexed: 12/24/2022]
Abstract
Animal studies have been instrumental in providing knowledge about the molecular and neural mechanisms underlying drug addiction. Recently, the fruit fly Drosophilamelanogaster has become a valuable system to model not only the acute stimulating and sedating effects of drugs but also their more complex rewarding properties. In this review, we describe the advantages of using the fly to study drug-related behavior, provide a brief overview of the behavioral assays used, and review the molecular mechanisms and neural circuits underlying drug-induced behavior in flies. Many of these mechanisms have been validated in mammals, suggesting that the fly is a useful model to understand the mechanisms underlying addiction.
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Affiliation(s)
- Karla R Kaun
- Department of Anatomy, University of California-San Francisco, 1550 4th Street, San Francisco, CA 94158, USA
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Krishnan HR, Al-Hasan YM, Pohl JB, Ghezzi A, Atkinson NS. A role for dynamin in triggering ethanol tolerance. Alcohol Clin Exp Res 2012; 36:24-34. [PMID: 21797886 PMCID: PMC3208067 DOI: 10.1111/j.1530-0277.2011.01587.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND A prevailing hypothesis is that the set of genes that underlie the endophenotypes of alcoholism overlap with those responsible for the addicted state. Functional ethanol tolerance, an endophenotype of alcoholism, is defined as a reduced response to ethanol caused by prior ethanol exposure. The neuronal origins of functional rapid tolerance are thought to be a homeostatic response of the nervous system that counters the effects of the drug. Synaptic proteins that regulate neuronal activity are an important evolutionarily conserved target of ethanol. METHODS We used mutant analysis in Drosophila to identify synaptic proteins that are important for the acquisition of rapid tolerance to sedation with ethanol. Tolerance was assayed by sedating flies with ethanol vapor and comparing the recovery time of flies after their first sedation and their second sedation. Temperature-sensitive paralytic mutants that alter key facets of synaptic neurotransmission, such as the propagation of action potentials, synaptic vesicle fusion, exocytosis, and endocytosis, were tested for the ability to acquire functional tolerance at both the permissive and restrictive temperatures. RESULTS The shibire gene encodes Drosophila Dynamin. We tested 2 temperature-sensitive alleles of the gene. The shi(ts1) allele blocked tolerance at both the permissive and restrictive temperatures, while shi(ts2) blocked only at the restrictive temperature. Using the temperature-sensitive property of shi(ts2) , we showed that Dynamin function is required concomitant with exposure to ethanol. A temperature-sensitive allele of the Syntaxin 1A gene, Syx1A(3-69), also blocked the acquisition of ethanol tolerance. CONCLUSIONS We have shown that shibire and Syntaxin 1A are required for the acquisition of rapid functional tolerance to ethanol. Furthermore, the shibire gene product, Dynamin, appears to be required for an immediate early response to ethanol that triggers a cellular response leading to rapid functional tolerance.
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Affiliation(s)
- Harish R Krishnan
- Waggoner Center for Alcohol and Addiction Research, Section of Neurobiology, The University of Texas at Austin, USA
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Linde KVD, Lyons LC. Circadian Modulation of Acute Alcohol Sensitivity But Not Acute Tolerance inDrosophila. Chronobiol Int 2011; 28:397-406. [DOI: 10.3109/07420528.2011.577921] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Tolerance to anesthesia depends on synaptic proteins. Behav Genet 2011; 41:734-45. [PMID: 21318409 DOI: 10.1007/s10519-011-9451-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Accepted: 01/28/2011] [Indexed: 12/17/2022]
Abstract
The hypnotic effects of anesthetics are caused by their interactions with neuronal components vital for proper signaling. An understanding of the adaptive mechanisms that lead to the development of anesthetic tolerance can offer insight into the regulation of neuroexcitability and plasticity that alter behavioral output. Here we use genetic and pharmacological manipulation of Drosophila to investigate the mechanisms of tolerance to benzyl alcohol. The mutants tested were temperature-sensitive paralytics that interfere with neuronal signaling: two mutations in dynamin that affect vesicle recycling, shi (ts1) and shi (ts2), and one that affects the voltage-activated Na(+) channel, para (ts1). We also used N-ethylmaleimide (NEM) to pharmacologically interfere with synaptic function. We found that blocking the generation of action potentials using a temperature-sensitive paralytic mutation does not induce nor prevent the development of functional tolerance to benzyl alcohol, but that disruption of synaptic signaling using mutations in the dynamin gene or by NEM treatment inhibits the induction of tolerance.
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Ghezzi A, Atkinson NS. Homeostatic control of neural activity: a Drosophila model for drug tolerance and dependence. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2011; 99:23-50. [PMID: 21906535 PMCID: PMC4862361 DOI: 10.1016/b978-0-12-387003-2.00002-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Drug addiction is a complex condition of compulsive drug use that results in devastating physical and social consequences. Drosophila melanogaster has recently emerged as a valuable genetic model for investigating the mechanisms of addiction. Drug tolerance is a measurable endophenotype of addiction that can be easily generated and detected in animal models. The counteradaptive theory for drug dependence postulates that the homeostatic adaptations that produce drug tolerance become counteradaptive after drug clearance, resulting in symptoms of dependence. In flies, a single sedation with ethanol or with an organic solvent anesthetic (benzyl alcohol) induces functional tolerance, an adaptation of the nervous system that reduces the effect of these neural depressants. Here we review the role of the BK channel gene (slo) and genes that encode other synaptic proteins in the process of producing functional tolerance. These proteins are predicted to be part of an orchestrated response that involves specific interactions across a highly complex synaptic protein network. The response of the slo gene to drug exposure and the consequence of induced slo expression fit nicely the tenets of the counteradaptive theory for drug tolerance and dependence. Induction of slo expression represents an adaptive process that generates tolerance because it enhances neuronal excitability, which counters the sedative effects of the drugs. After drug clearance, however, the increase in slo expression leads to an allostatic withdrawal state that is characterized by an increase in the susceptibility for seizure. Together, these results demonstrate a common origin for development of drug tolerance and withdrawal hyperexcitability in Drosophila.
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Affiliation(s)
- Alfredo Ghezzi
- Waggoner Center for Alcohol and Addiction Research, Section of Neurobiology, The University of Texas at Austin, 1 University Station C0920, Austin Texas 78712-0248, USA
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Awofala AA. Genetic approaches to alcohol addiction: gene expression studies and recent candidates from Drosophila. INVERTEBRATE NEUROSCIENCE 2010; 11:1-7. [PMID: 21153676 DOI: 10.1007/s10158-010-0113-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2010] [Accepted: 11/25/2010] [Indexed: 12/27/2022]
Abstract
Ethanol intake causes gene expression changes resulting in cellular and molecular adaptations that could be associated with a predisposition to alcohol dependence. Recently, several research groups have used high-throughput gene expression profiling to search for alcohol-responsive genes in Drosophila melanogaster. Comparison of data from these studies highlights the functional similarities in their results despite differences in their experimental approach and selection cases. Notably, alcohol-responsive gene sets associated with stress response, olfaction, metabolism, proteases, transcriptional regulation, regulation of signal transduction, nucleic acid binding and cytoskeletal organisation were markedly common to these studies. These data support the view that changes in gene expression in alcoholics are associated with widespread cellular functions.
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Affiliation(s)
- Awoyemi A Awofala
- Department of Biology and Environmental Science, School of Life Sciences, University of Sussex, Brighton, UK.
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Manev H, Dzitoyeva S. GABA-B Receptors in Drosophila. GABABRECEPTOR PHARMACOLOGY - A TRIBUTE TO NORMAN BOWERY 2010; 58:453-64. [DOI: 10.1016/s1054-3589(10)58017-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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