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Scaplen KM, Petruccelli E. Receptors and Channels Associated with Alcohol Use: Contributions from Drosophila. Neurosci Insights 2021; 16:26331055211007441. [PMID: 33870197 PMCID: PMC8020223 DOI: 10.1177/26331055211007441] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 03/03/2021] [Indexed: 12/14/2022] Open
Abstract
Alcohol Use Disorder (AUD) is a debilitating disorder that manifests as problematic patterns of alcohol use. At the core of AUD's behavioral manifestations are the profound structural, physiological, cellular, and molecular effects of alcohol on the brain. While the field has made considerable progress in understanding the neuromolecular targets of alcohol we still lack a comprehensive understanding of alcohol's actions and effective treatment strategies. Drosophila melanogaster is a powerful model for investigating the neuromolecular targets of alcohol because flies model many of the core behavioral elements of AUD and offer a rich genetic toolkit to precisely reveal the in vivo molecular actions of alcohol. In this review, we focus on receptors and channels that are often targeted by alcohol within the brain. We discuss the general roles of these proteins, their role in alcohol-associated behaviors across species, and propose ways in which Drosophila models can help advance the field.
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Affiliation(s)
- Kristin M Scaplen
- Department of Psychology, Bryant University, Smithfield, RI, USA
- Center for Health and Behavioral Studies, Bryant University, Smithfield, RI, USA
- Department of Neuroscience, Brown University, Providence, RI, USA
| | - Emily Petruccelli
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, USA
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Ethanol Regulates Presynaptic Activity and Sedation through Presynaptic Unc13 Proteins in Drosophila. eNeuro 2018; 5:eN-NWR-0125-18. [PMID: 29911175 PMCID: PMC6001265 DOI: 10.1523/eneuro.0125-18.2018] [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: 03/30/2018] [Revised: 05/09/2018] [Accepted: 05/12/2018] [Indexed: 11/21/2022] Open
Abstract
Ethanol has robust effects on presynaptic activity in many neurons, however, it is not yet clear how this drug acts within this compartment to change neural activity, nor the significance of this change on behavior and physiology in vivo. One possible presynaptic effector for ethanol is the Munc13-1 protein. Herein, we show that ethanol binding to the rat Munc13-1 C1 domain, at concentrations consistent with binge exposure, reduces diacylglycerol (DAG) binding. The inhibition of DAG binding is predicted to reduce the activity of Munc13-1 and presynaptic release. In Drosophila, we show that sedating concentrations of ethanol significantly reduce synaptic vesicle release in olfactory sensory neurons (OSNs), while having no significant impact on membrane depolarization and Ca2+ influx into the presynaptic compartment. These data indicate that ethanol targets the active zone in reducing synaptic vesicle exocytosis. Drosophila, haploinsufficent for the Munc13-1 ortholog Dunc13, are more resistant to the effect of ethanol on presynaptic inhibition. Genetically reducing the activity of Dunc13 through mutation or expression of RNAi transgenes also leads to a significant resistance to the sedative effects of ethanol. The neuronal expression of Munc13-1 in heterozygotes for a Dunc13 loss-of-function mutation can largely rescue the ethanol sedation resistance phenotype, indicating a conservation of function between Munc13-1 and Dunc13 in ethanol sedation. Hence, reducing Dunc13 activity leads to naïve physiological and behavioral resistance to sedating concentrations of ethanol. We propose that reducing Dunc13 activity, genetically or pharmacologically by ethanol binding to the C1 domain of Munc13-1/Dunc13, promotes a homeostatic response that leads to ethanol tolerance.
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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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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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Behavioral Deficits Following Withdrawal from Chronic Ethanol Are Influenced by SLO Channel Function in Caenorhabditis elegans. Genetics 2017; 206:1445-1458. [PMID: 28546434 DOI: 10.1534/genetics.116.193102] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 04/29/2017] [Indexed: 01/03/2023] Open
Abstract
Symptoms of withdrawal from chronic alcohol use are a driving force for relapse in alcohol dependence. Thus, uncovering molecular targets to lessen their severity is key to breaking the cycle of dependence. Using the nematode Caenorhabditis elegans, we tested whether one highly conserved ethanol target, the large-conductance, calcium-activated potassium channel (known as the BK channel or Slo1), modulates ethanol withdrawal. Consistent with a previous report, we found that C. elegans displays withdrawal-related behavioral impairments after cessation of chronic ethanol exposure. We found that the degree of impairment is exacerbated in worms lacking the worm BK channel, SLO-1, and is reduced by selective rescue of this channel in the nervous system. Enhanced SLO-1 function, via gain-of-function mutation or overexpression, also dramatically reduced behavioral impairment during withdrawal. Consistent with these results, we found that chronic ethanol exposure decreased SLO-1 expression in a subset of neurons. In addition, we found that the function of a distinct, conserved Slo family channel, SLO-2, showed an inverse relationship to withdrawal behavior, and this influence depended on SLO-1 function. Together, our findings show that modulation of either Slo family ion channel bidirectionally regulates withdrawal behaviors in worm, supporting further exploration of the Slo family as targets for normalizing behaviors during alcohol withdrawal.
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Ghezzi A, Li X, Lew LK, Wijesekera TP, Atkinson NS. Alcohol-Induced Neuroadaptation Is Orchestrated by the Histone Acetyltransferase CBP. Front Mol Neurosci 2017; 10:103. [PMID: 28442993 PMCID: PMC5387060 DOI: 10.3389/fnmol.2017.00103] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 03/24/2017] [Indexed: 12/19/2022] Open
Abstract
Homeostatic neural adaptations to alcohol underlie the production of alcohol tolerance and the associated symptoms of withdrawal. These adaptations have been shown to persist for relatively long periods of time and are believed to be of central importance in promoting the addictive state. In Drosophila, a single exposure to alcohol results in long-lasting alcohol tolerance and symptoms of withdrawal following alcohol clearance. These persistent adaptations involve mechanisms such as long-lasting changes in gene expression and perhaps epigenetic restructuring of chromosomal regions. Histone modifications have emerged as important modulators of gene expression and are thought to orchestrate and maintain the expression of multi-gene networks. Previously genes that contribute to tolerance were identified as those that show alcohol-induced changes in histone H4 acetylation following a single alcohol exposure. However, the molecular mediator of the acetylation process that orchestrates their expression remains unknown. Here we show that the Drosophila ortholog of mammalian CBP, nejire, is the histone acetyltransferase involved in regulatory changes producing tolerance—alcohol induces nejire expression, nejire mutations suppress tolerance, and transgenic nejire induction mimics tolerance in alcohol-naive animals. Moreover, we observed that a loss-of-function mutation in the alcohol tolerance gene slo epistatically suppresses the effects of CBP induction on alcohol resistance, linking nejire to a well-established alcohol tolerance gene network. We propose that CBP is a central regulator of the network of genes underlying an alcohol adaptation.
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Affiliation(s)
- Alfredo Ghezzi
- Department of Biology, University of Puerto Rico, Río Piedras CampusSan Juan, Puerto Rico
| | - Xiaolei Li
- Department of Neuroscience and Waggoner Center for Alcohol and Addiction Research, The University of Texas at AustinAustin, TX, USA
| | - Linda K Lew
- Department of Neuroscience and Waggoner Center for Alcohol and Addiction Research, The University of Texas at AustinAustin, TX, USA
| | - Thilini P Wijesekera
- Department of Neuroscience and Waggoner Center for Alcohol and Addiction Research, The University of Texas at AustinAustin, TX, USA
| | - Nigel S Atkinson
- Department of Neuroscience and Waggoner Center for Alcohol and Addiction Research, The University of Texas at AustinAustin, TX, USA
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Park A, Ghezzi A, Wijesekera TP, Atkinson NS. Genetics and genomics of alcohol responses in Drosophila. Neuropharmacology 2017; 122:22-35. [PMID: 28161376 DOI: 10.1016/j.neuropharm.2017.01.032] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Revised: 01/24/2017] [Accepted: 01/29/2017] [Indexed: 02/07/2023]
Abstract
Drosophila melanogaster has become a significant model organism for alcohol research. In flies, a rich variety of behaviors can be leveraged for identifying genes affecting alcohol responses and adaptations. Furthermore, almost all genes can be easily genetically manipulated. Despite the great evolutionary distance between flies and mammals, many of the same genes have been implicated in strikingly similar alcohol-induced behaviors. A major problem in medical research today is that it is difficult to extrapolate from any single model system to humans. Strong evolutionary conservation of a mechanistic response between distantly related organisms, such as flies and mammals, is a powerful predictor that conservation will continue all the way to humans. This review describes the state of the Drosophila alcohol research field. It describes common alcohol behavioral assays, the independent origins of resistance and tolerance, the results of classical genetic screens and candidate gene analysis, and the outcomes of recent genomics studies employing GWAS, transcriptome, miRNA, and genome-wide histone acetylation surveys. This article is part of the Special Issue entitled "Alcoholism".
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Affiliation(s)
- Annie Park
- Department of Neuroscience and The Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, United States
| | - Alfredo Ghezzi
- Department of Biology, University of Puerto Rico, Rio Piedras. San Juan, PR, United States
| | - Thilini P Wijesekera
- Department of Neuroscience and The Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, United States
| | - Nigel S Atkinson
- Department of Neuroscience and The Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, United States.
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Abstract
This is a brief reminiscence of my time in the Ganetzky lab from 1986-1990 and its effect on my scientific trajectory.
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Affiliation(s)
- Nigel S Atkinson
- a Department of Neuroscience and The Waggoner Center for Alcohol and Addiction Research , College of Natural Sciences, The University of Texas at Austin , Austin , TX , USA
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Dopico AM, Bukiya AN, Kuntamallappanavar G, Liu J. Modulation of BK Channels by Ethanol. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 128:239-79. [PMID: 27238266 PMCID: PMC5257281 DOI: 10.1016/bs.irn.2016.03.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In alcohol-naïve systems, ethanol (<100mM) exposure of calcium-gated BK channels perturbs physiology and behavior. Brief (several minutes) ethanol exposure usually leads to increased BK current, which results from ethanol interaction with a pocket mapped to the BK channel-forming slo1 protein cytosolic tail domain. The importance of this region in ethanol-induced intoxication has been independently supported by an unbiased screen of Caenorhabditis elegans slo1 mutants. However, ethanol-induced BK activation is not universal as refractoriness and inhibition have been reported. The final effect depends on many factors, including intracellular calcium levels, slo1 isoform, BK beta subunit composition, posttranslational modification of BK proteins, channel lipid microenvironment, and type of ethanol administration. Studies in Drosophila melanogaster, C. elegans, and rodents show that protracted/repeated ethanol administration leads to tolerance to ethanol-induced modification of BK-driven physiology and behavior. Unveiling the mechanisms underlying tolerance is of major importance, as tolerance to ethanol has been proposed as predictor of risk for alcoholism.
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Affiliation(s)
- A M Dopico
- College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, United States.
| | - A N Bukiya
- College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, United States
| | - G Kuntamallappanavar
- College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, United States
| | - J Liu
- College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, United States
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A DNA element in the slo gene modulates ethanol tolerance. Alcohol 2016; 51:37-42. [PMID: 26992698 DOI: 10.1016/j.alcohol.2015.12.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 12/23/2015] [Accepted: 12/23/2015] [Indexed: 12/20/2022]
Abstract
In Drosophila, the slo gene encodes BK-type Ca(2+)-activated K(+) channels and is involved in producing rapid functional tolerance to sedation with ethanol. Drosophila are ideal for the study of functional ethanol tolerance because the adult does not acquire metabolic ethanol tolerance (Scholz, Ramond, Singh, & Heberlein, 2000). It has been shown that mutations in slo block the capacity to acquire tolerance, that sedation with ethanol vapor induces slo gene expression in the nervous system, and that transgenic induction of slo can phenocopy tolerance (Cowmeadow, Krishnan, & Atkinson, 2005; Cowmeadow et al., 2006). Here we use ethanol-induced histone acetylation to map a DNA regulatory element in the slo transcriptional control region and functionally test the element for a role in producing ethanol tolerance. Histone acetylation is commonly associated with activating transcription factors. We used the chromatin immunoprecipitation assay to map histone acetylation changes following ethanol sedation to identify an ethanol-responsive DNA element. Ethanol sedation induced an increase in histone acetylation over a 60 n DNA element called 6b, which is situated between the two ethanol-responsive neural promoters of the slo gene. Removal of the 6b element from the endogenous slo gene affected the production of functional ethanol tolerance as assayed in an ethanol-vapor recovery from sedation assay. Removal of element 6b extended the period of functional ethanol tolerance from ∼10 days to more than 21 days after a single ethanol-vapor sedation. This study demonstrates that mapping the position of ethanol-induced histone acetylation is an effective way to identify DNA regulatory elements that help to mediate the response of a gene to ethanol. Using this approach, we identified a DNA element, which is conserved among Drosophila species, and which is important for producing a behaviorally relevant ethanol response.
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Li X, Ghezzi A, Krishnan HR, Pohl JB, Bohm AY, Atkinson NS. A histone modification identifies a DNA element controlling slo BK channel gene expression in muscle. J Neurogenet 2015; 29:124-34. [PMID: 25967280 DOI: 10.3109/01677063.2015.1050097] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The slo gene encodes the BK-type Ca(2+)-activated K(+) channels. In Drosophila, expression of slo is induced by organic solvent sedation (benzyl alcohol and ethanol), and this increase in neural slo expression contributes to the production of functional behavioral tolerance (inducible resistance) to these drugs. Within the slo promoter region, we observed that benzyl alcohol sedation produces a localized spike of histone acetylation over a 65-nucleotide (65-n) conserved DNA element called 55b. Changes in histone acetylation are commonly the consequence of transcription factor activity, and previously, a localized histone acetylation spike was used to successfully map a DNA element involved in benzyl alcohol-induced slo expression. To determine whether the 55b element was also involved in benzyl alcohol-induced neural expression of slo, we deleted it from the endogenous slo gene by homologous recombination. Flies lacking the 55b element were normal with respect to basal and benzyl alcohol-induced neural slo expression, the capacity to acquire and maintain functional tolerance, their threshold for electrically-induced seizures, and most slo-related behaviors. Removal of the 55b element did however increase the level of basal expression from the muscle/tracheal cell-specific slo core promoter and produced a slight increase in overall locomotor activity. We conclude that the 55b element is involved in control of slo expression from the muscle and tracheal-cell promoter but is not involved in the production of functional benzyl alcohol tolerance.
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Affiliation(s)
- Xiaolei Li
- a School of Biological Sciences, Nanyang Technological University , Singapore
| | - Alfredo Ghezzi
- b Department of Neuroscience and The Waggoner Center for Alcohol and Addiction Research , The University of Texas at Austin , Austin, Texas , USA
| | - Harish R Krishnan
- c Department of Psychiatry , University of Illinois at Chicago and Jesse Brown VA Medical Center , Chicago , IL , USA
| | - Jascha B Pohl
- b Department of Neuroscience and The Waggoner Center for Alcohol and Addiction Research , The University of Texas at Austin , Austin, Texas , USA
| | - Arun Y Bohm
- b Department of Neuroscience and The Waggoner Center for Alcohol and Addiction Research , The University of Texas at Austin , Austin, Texas , USA
| | - Nigel S Atkinson
- b Department of Neuroscience and The Waggoner Center for Alcohol and Addiction Research , The University of Texas at Austin , Austin, Texas , USA
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