title: Glutamatergic neurotransmission in the procerebrum (olfactory center) of a terrestrial mollusk.
abstract: The terrestrial slug Limax has the ability to learn odor associations. This ability depends on the function of the procerebrum, the secondary olfactory center in the brain. Among the various neurotransmitters that are thought to be involved in the function of the procerebrum, glutamate is one of the most important molecules. However, the existence and function of glutamate in this system have been proposed solely on the basis of a few lines of indirect evidence from pharmacological experiments. In the present study, we demonstrated the existence and release of glutamate as a neurotransmitter in the procerebrum of Limax, by using three different techniques: 1) immunohistochemistry of glutamate, 2) in situ hybridization to mRNA of the vesicular glutamate transporter, and 3) real-time imaging of glutamate release within the procerebrum using the glutamate optical sensor EOS2. The release of glutamate within the cell mass layer of the procerebrum was synchronized with oscillation of the local field potential and had the same physiological properties as this oscillation; both were blocked by a serotonin antagonist and were propagated in an apical to basal direction in the procerebrum. Our observations suggest strongly that the oscillation of the local field potential is driven by the glutamate released by bursting neurons in the procerebrum.
authors.affiliation: Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Kagawa, Japan. matsuor@kph.bunri-u.ac.jp
authors.forename: Ryota
authors.initials: R
authors.lastname: Matsuo
authors.forename: Suguru
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Watanabe
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Namiki
authors.forename: Sho
authors.initials: S
authors.lastname: Iinuma
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Sakamoto
authors.forename: Kenzo
authors.initials: K
authors.lastname: Hirose
authors.forename: Etsuro
authors.initials: E
authors.lastname: Ito
mesh_terms: D000200:Action Potentials; D000595:Amino Acid Sequence; D000825:Animal Structures / Q000502:physiology; D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology; D049851:Gastropoda / Q000502:physiology*; D018698:Glutamic Acid / Q000502:physiology*; D007051:Ibotenic Acid / Q000494:pharmacology; D008969:Molecular Sequence Data; D009833:Olfactory Pathways / Q000502:physiology*; D010802:Phylogeny; D011810:Quinoxalines / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012702:Serotonin Antagonists / Q000494:pharmacology; D012903:Smell / Q000502:physiology*; D013045:Species Specificity; D009435:Synaptic Transmission / Q000502:physiology*; D050496:Vesicular Glutamate Transport Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics
chemical_list: D011810:Quinoxalines; D012333:RNA, Messenger; D012702:Serotonin Antagonists; D050496:Vesicular Glutamate Transport Proteins; C062865:2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline; D007051:Ibotenic Acid; D018698:Glutamic Acid