title: Gene expression changes in a zebrafish model of drug dependency suggest conservation of neuro-adaptation pathways.
abstract: Addiction is a complex psychiatric disorder considered to be a disease of the brain's natural reward reinforcement system. Repeated stimulation of the 'reward' pathway leads to adaptive changes in gene expression and synaptic organization that reinforce drug taking and underlie long-term changes in behaviour. The primitive nature of reward reinforcement pathways and the near universal ability of abused drugs to target the same system allow drug-associated reward and reinforcement to be studied in non-mammalian species. Zebrafish have proved to be a valuable model system for the study of vertebrate development and disease. Here we demonstrate that adult zebrafish show a dose-dependent acute conditioned place preference (CPP) reinforcement response to ethanol or nicotine. Repeated exposure of adult zebrafish to either nicotine or ethanol leads to a robust CPP response that persists following 3 weeks of abstinence and in the face of adverse stimuli, a behavioural indicator of the establishment of dependence. Microarray analysis using whole brain samples from drug-treated and control zebrafish identified 1362 genes that show a significant change in expression between control and treated individuals. Of these genes, 153 are common to both ethanol- and nicotine-treated animals. These genes include members of pathways and processes implicated in drug dependence in mammalian models, revealing conservation of neuro-adaptation pathways between zebrafish and mammals.
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End, London E1 4NS, UK.
authors.forename: Layla J M
authors.initials: LJ
authors.lastname: Kily
authors.forename: Yuka C M
authors.initials: YC
authors.lastname: Cowe
authors.forename: Osman
authors.initials: O
authors.lastname: Hussain
authors.forename: Salma
authors.initials: S
authors.lastname: Patel
authors.forename: Suzanne
authors.initials: S
authors.lastname: McElwaine
authors.forename: Finbarr E
authors.initials: FE
authors.lastname: Cotter
authors.forename: Caroline H
authors.initials: CH
authors.lastname: Brennan
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002633:Chemotaxis / Q000187:drug effects*; D017931:DNA Primers / Q000235:genetics; D000431:Ethanol / Q000633:toxicity; D005786:Gene Expression Regulation / Q000187:drug effects*; D009538:Nicotine / Q000633:toxicity; D020411:Oligonucleotide Array Sequence Analysis; D012054:Reinforcement, Psychology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012201:Reward; D019966:Substance-Related Disorders / Q000378:metabolism*; D015027:Zebrafish
chemical_list: D017931:DNA Primers; D000431:Ethanol; D009538:Nicotine