title: Roles of OA1 octopamine receptor and Dop1 dopamine receptor in mediating appetitive and aversive reinforcement revealed by RNAi studies.
abstract: Revealing reinforcing mechanisms in associative learning is important for elucidation of brain mechanisms of behavior. In mammals, dopamine neurons are thought to mediate both appetitive and aversive reinforcement signals. Studies using transgenic fruit-flies suggested that dopamine neurons mediate both appetitive and aversive reinforcements, through the Dop1 dopamine receptor, but our studies using octopamine and dopamine receptor antagonists and using Dop1 knockout crickets suggested that octopamine neurons mediate appetitive reinforcement and dopamine neurons mediate aversive reinforcement in associative learning in crickets. To fully resolve this issue, we examined the effects of silencing of expression of genes that code the OA1 octopamine receptor and Dop1 and Dop2 dopamine receptors by RNAi in crickets. OA1-silenced crickets exhibited impairment in appetitive learning with water but not in aversive learning with sodium chloride solution, while Dop1-silenced crickets exhibited impairment in aversive learning but not in appetitive learning. Dop2-silenced crickets showed normal scores in both appetitive learning and aversive learning. The results indicate that octopamine neurons mediate appetitive reinforcement via OA1 and that dopamine neurons mediate aversive reinforcement via Dop1 in crickets, providing decisive evidence that neurotransmitters and receptors that mediate appetitive reinforcement indeed differ among different species of insects.
authors.affiliation: Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Awata
authors.affiliation: Graduate School of Live Sciences, Hokkaido University, Sapporo, 060-0810, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Wakuda
authors.affiliation: Department of Life Systems, Institute of Technology and Science, Tokushima University, Tokushima 770-8506, Japan.
authors.forename: Yoshiyasu
authors.initials: Y
authors.lastname: Ishimaru
authors.affiliation: Department of Life Systems, Institute of Technology and Science, Tokushima University, Tokushima 770-8506, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Matsuoka
authors.affiliation: Graduate School of Live Sciences, Hokkaido University, Sapporo, 060-0810, Japan.
authors.forename: Kanta
authors.initials: K
authors.lastname: Terao
authors.affiliation: Graduate School of Live Sciences, Hokkaido University, Sapporo, 060-0810, Japan.
authors.forename: Satomi
authors.initials: S
authors.lastname: Katata
authors.affiliation: Faculty of Liberal Arts, Tokyo Medical and Dental University, Ichikawa 272-0827, Japan.
authors.forename: Yukihisa
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Hamanaka
authors.affiliation: Department of Life Systems, Institute of Technology and Science, Tokushima University, Tokushima 770-8506, Japan.
authors.forename: Sumihare
authors.initials: S
authors.lastname: Noji
authors.affiliation: Department of Life Systems, Institute of Technology and Science, Tokushima University, Tokushima 770-8506, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Mito
authors.affiliation: Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Mizunami
mesh_terms: D000818:Animals; D001070:Appetitive Behavior / Q000502:physiology*; D001362:Avoidance Learning / Q000502:physiology*; D059290:Dopaminergic Neurons / Q000378:metabolism / Q000502:physiology; D006135:Gryllidae / Q000235:genetics / Q000502:physiology; D019476:Insect Proteins / Q000235:genetics / Q000502:physiology*; D008297:Male; D008568:Memory / Q000502:physiology; D009474:Neurons / Q000378:metabolism / Q000502:physiology; D009655:Octopamine / Q000378:metabolism; D034622:RNA Interference; D017982:Receptors, Biogenic Amine / Q000235:genetics / Q000502:physiology*; D011954:Receptors, Dopamine / Q000235:genetics / Q000502:physiology*; D012054:Reinforcement, Psychology
chemical_list: D019476:Insect Proteins; D017982:Receptors, Biogenic Amine; D011954:Receptors, Dopamine; C027604:norsynephrine receptor; D009655:Octopamine