title: Octopamine receptors from the barnacle balanus improvisus are activated by the alpha2-adrenoceptor agonist medetomidine.
abstract: G protein-coupled octopamine receptors of insects and other invertebrates represent counterparts of adrenoceptors in vertebrate animals. The alpha(2)-adrenoceptor agonist medetomidine, which is in clinical use as a veterinary sedative agent, was discovered to inhibit the settling process of barnacles, an important step in the ontogeny of this crustacean species. Settling of barnacles onto ship hulls leads to biofouling that has many harmful practical consequences, and medetomidine is currently under development as a novel type of antifouling agent. We now report that medetomidine induces hyperactivity in the barnacle larvae to disrupt the settling process. To identify the molecular targets of medetomidine, we cloned five octopamine receptors from the barnacle Balanus improvisus. We show by phylogenetic analyses that one receptor (BiOctalpha) belongs to the alpha-adrenoceptor-like subfamily, and the other four (BiOctbeta-R1, BiOctbeta-R2, BiOctbeta-R3, and BiOctbeta-R4) belong to the beta-adrenoceptor-like octopamine receptor subfamily. Phylogenetic analyses also indicated that B. improvisus has a different repertoire of beta-adrenoceptor-like octopamine receptors than insects. When expressed in CHO cells, the cloned receptors were activated by both octopamine and medetomidine, resulting in increased intracellular cAMP or calcium levels. Tyramine activated the receptors but with much lesser potency than octopamine. A hypothesis for receptor discrimination between tyramine and octopamine was generated from a homology three-dimensional model. The characterization of B. improvisus octopamine receptors is important for a better functional understanding of these receptors in crustaceans as well as for practical applications in development of environmentally sustainable antifouling agents.
authors.affiliation: Department of Cell and Molecular Biology,University of Gothenburg, Gothenburg, Sweden.
authors.forename: Ulrika
authors.initials: U
authors.lastname: Lind
authors.forename: Magnus
authors.initials: M
authors.lastname: Alm Rosenblad
authors.forename: Linda
authors.initials: L
authors.lastname: Hasselberg Frank
authors.forename: Susanna
authors.initials: S
authors.lastname: Falkbring
authors.forename: Lars
authors.initials: L
authors.lastname: Brive
authors.forename: Jonne M
authors.initials: JM
authors.lastname: Laurila
authors.forename: Katariina
authors.initials: K
authors.lastname: Pohjanoksa
authors.forename: Anne
authors.initials: A
authors.lastname: Vuorenpää
authors.forename: Jyrki P
authors.initials: JP
authors.lastname: Kukkonen
authors.forename: Lina
authors.initials: L
authors.lastname: Gunnarsson
authors.forename: Mika
authors.initials: M
authors.lastname: Scheinin
authors.forename: Lena G E
authors.initials: LG
authors.lastname: Mårtensson Lindblad
authors.forename: Anders
authors.initials: A
authors.lastname: Blomberg
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D003001:Cloning, Molecular; D006224:Cricetinae; D003412:Cricetulus; D020926:Medetomidine / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D017982:Receptors, Biogenic Amine / Q000819:agonists* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D001468:Thoracica
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists; D017982:Receptors, Biogenic Amine; C027604:norsynephrine receptor; D020926:Medetomidine