title: Cloning of the GABABReceptor Subunits B1 and B2 and their Expression in the Central Nervous System of the Adult Sea Lamprey.
abstract: In vertebrates, γ-aminobutyric acid (GABA) is the main inhibitory transmitter in the central nervous system (CNS) acting through ionotropic (GABAA) and metabotropic (GABAB) receptors. The GABABreceptor produces a slow inhibition since it activates second messenger systems through the binding and activation of guanine nucleotide-binding proteins [G-protein-coupled receptors (GPCRs)]. Lampreys are a key reference to understand molecular evolution in vertebrates. The importance of the GABABreceptor for the modulation of the circuits controlling locomotion and other behaviors has been shown in pharmacological/physiological studies in lampreys. However, there is no data about the sequence of the GABABsubunits or their expression in the CNS of lampreys. Our aim was to identify the sea lamprey GABAB1and GABAB2transcripts and study their expression in the CNS of adults. We cloned two partial sequences corresponding to the GABAB1and GABAB2cDNAs of the sea lamprey as confirmed by sequence analysis and comparison with known GABABsequences of other vertebrates. In phylogenetic analyses, the sea lamprey GABABsequences clustered together with GABABs sequences of vertebrates and emerged as an outgroup to all gnathostome sequences. We observed a broad and overlapping expression of both transcripts in the entire CNS. Expression was mainly observed in neuronal somas of the periventricular regions including the identified reticulospinal cells. No expression was observed in identifiable fibers. Comparison of our results with those reported in other vertebrates indicates that a broad and overlapping expression of the GABABsubunits in the CNS is a conserved character shared by agnathans and gnathostomes.
authors.affiliation: Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela Santiago de Compostela, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Romaus-Sanjurjo
authors.affiliation: Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela Santiago de Compostela, Spain.
authors.forename: Blanca
authors.initials: B
authors.lastname: Fernández-López
authors.affiliation: Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela Santiago de Compostela, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Sobrido-Cameán
authors.affiliation: Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela Santiago de Compostela, Spain.
authors.forename: Antón
authors.initials: A
authors.lastname: Barreiro-Iglesias
authors.affiliation: Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela Santiago de Compostela, Spain.
authors.forename: María Celina
authors.initials: MC
authors.lastname: Rodicio
keywords: GABA; GABAB1; GABAB2; agnathans; receptor heterodimerization