title: Characterization of the γ-aminobutyric acid signaling system in the zebrafish (Danio rerio Hamilton) central nervous system by reverse transcription-quantitative polymerase chain reaction.
abstract: In the vertebrate brain, inhibition is largely mediated by γ-aminobutyric acid (GABA). This neurotransmitter comprises a signaling machinery of GABAA, GABABreceptors, transporters, glutamate decarboxylases (gads) and 4-aminobutyrate aminotransferase (abat), and associated proteins. Chloride is intimately related to GABAAreceptor conductance, GABA uptake, and GADs activity. The response of target neurons to GABA stimuli is shaped by chloride-cation co-transporters (CCCs), which strictly control Cl-gradient across plasma membranes. This research profiled the expression of forty genes involved in GABA signaling in the zebrafish (Danio rerio) brain, grouped brain regions and retinas. Primer pairs were developed for reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The mRNA levels of the zebrafish GABA system share similarities with that of mammals, and confirm previous studies in non-mammalian species. Proposed GABAAreceptors are α1β2γ2, α1β2δ, α2bβ3γ2, α2bβ3δ, α4β2γ2, α4β2δ, α6bβ2γ2and α6bβ2δ. Regional brain differences were documented. Retinal hetero- or homomeric ρ-composed GABAAreceptors could exist, accompanying α1βyγ2, α1βyδ, α6aβyγ2, α6aβyδ. Expression patterns of α6aand α6bwere opposite, with the former being more abundant in retinas, the latter in brains. Given the stoichiometry α6wβyγz, α6a- or α6b-containing receptors likely have different regulatory mechanisms. Different gene isoforms could originate after the rounds of genome duplication during teleost evolution. This research depicts that one isoform is generally more abundantly expressed than the other. Such observations also apply to GABABreceptors, GABA transporters, GABA-related enzymes, CCCs and GABAAreceptor-associated proteins, whose presence further strengthens the proof of a GABA system in zebrafish.
authors.affiliation: Department of Neuroscience, Biomedical Centre, Uppsala University, P.O. Box 593, 751 24 Uppsala, Sweden. Electronic address: arianna.cocco@neuro.uu.se.
authors.forename: Arianna
authors.initials: A
authors.lastname: Cocco
authors.affiliation: Department of Neuroscience, Biomedical Centre, Uppsala University, P.O. Box 593, 751 24 Uppsala, Sweden. Electronic address: carrr0-@hotmail.com.
authors.forename: A M Carolina
authors.initials: AM
authors.lastname: Rönnberg
authors.affiliation: Department of Neuroscience, Biomedical Centre, Uppsala University, P.O. Box 593, 751 24 Uppsala, Sweden. Electronic address: zhe.jin@neuro.uu.se.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Jin
authors.affiliation: Department of Neuroscience, Biomedical Centre, Uppsala University, P.O. Box 593, 751 24 Uppsala, Sweden. Electronic address: goncalo.igrejaandre@research.uwa.edu.au.
authors.forename: Gonçalo Igreja
authors.initials: GI
authors.lastname: André
authors.affiliation: Department of Neuroscience, Biomedical Centre, Uppsala University, P.O. Box 593, 751 24 Uppsala, Sweden. Electronic address: laura.vossen@neuro.uu.se.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Vossen
authors.affiliation: Department of Neuroscience, Biomedical Centre, Uppsala University, P.O. Box 593, 751 24 Uppsala, Sweden. Electronic address: amol.bhandage@neuro.uu.se.
authors.forename: Amol K
authors.initials: AK
authors.lastname: Bhandage
authors.affiliation: Department of Neuroscience, Biomedical Centre, Uppsala University, P.O. Box 593, 751 24 Uppsala, Sweden. Electronic address: per-ove.thornqvist@neuro.uu.se.
authors.forename: Per-Ove
authors.initials: PO
authors.lastname: Thörnqvist
authors.affiliation: Department of Neuroscience, Biomedical Centre, Uppsala University, P.O. Box 593, 751 24 Uppsala, Sweden. Electronic address: bryndis.birnir@neuro.uu.se.
authors.forename: Bryndis
authors.initials: B
authors.lastname: Birnir
authors.affiliation: Department of Neuroscience, Biomedical Centre, Uppsala University, P.O. Box 593, 751 24 Uppsala, Sweden. Electronic address: svante.winberg@neuro.uu.se.
authors.forename: Svante
authors.initials: S
authors.lastname: Winberg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism*; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism*; D050485:GABA Plasma Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D011963:Receptors, GABA-A / Q000235:genetics / Q000378:metabolism*; D018080:Receptors, GABA-B / Q000235:genetics / Q000378:metabolism; D012160:Retina / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015027:Zebrafish / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D029941:Fish Proteins; D050485:GABA Plasma Membrane Transport Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D011963:Receptors, GABA-A; D018080:Receptors, GABA-B; D005680:gamma-Aminobutyric Acid
keywords: GABA; comparative neuroscience; neurotransmitter systems; receptors; teleost; zebrafish