title: Nitric oxide-coupled signaling in odor elicited molecular events in the olfactory center of the terrestrial snail, Helix pomatia.
abstract: Olfaction, a chemosensory modality, plays a pivotal role in the orientation and behavior of invertebrates. The central olfactory processing unit in terrestrial stylomatophoran snails is the procerebrum, which contains NO synthesizing interneurons, whose oscillatory currents are believed to be the base of odor evoked memory formation. Nevertheless, in this model the up- and downstream events of molecular cascades that trigger and follow NO release, respectively, have not been studied. Immunocytochemistry and flow cytometry studies performed on procerebral neural perikarya isolated from the snail Helix pomatia revealed cell populations with discrete DAF-2 fluorescence, indicating the release of different amounts of NO. Glutamate increased the intensity of DAF-2 fluorescence, and the number of DAF-2 positive non-bursting interneurons, through a mechanism likely to involve an NMDA-like receptor. Similarly to glutamate, NO activation induced an increase in intracellular cGMP levels through activation of soluble guanylyl cyclase. Immunohistochemical localization of proteins possessing the phosphorylated target sequence of AGC family kinases (RXXS/T-P), among them protein kinase A (RRXS/T-P), showed striking similarities to the distribution of NOS/cGMP. Activators of cyclic nucleotide synthesis increased the AGC-kinase-dependent phosphorylation of discrete proteins with 28, 45, and 55kDamw. Importantly, exposure of snails to an attractive odorant induced hyperphosphorylation of the 28kDa protein, and increased levels of cGMP synthesis. Protein S-nitrosylation and intercellular activation of protein kinase G were also suggested as alternative components of NO signaling in the snail procerebrum. The present results from Helix pomatia indicate an important role for procerebrum NO/cGMP/PKA signaling pathways in the regulation of olfactory (food-finding) behavior.
authors.affiliation: MTA Centre for Ecological Research, Balaton Limnological Institute, Tihany, Hungary. Electronic address: serfozo.zoltan@okologia.mta.hu.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Serfőző
authors.affiliation: MTA Centre for Ecological Research, Balaton Limnological Institute, Tihany, Hungary.
authors.forename: Kálmán
authors.initials: K
authors.lastname: Nacsa
authors.affiliation: Institute of Biochemistry and Molecular Biology, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Veréb
authors.affiliation: MTA Centre for Ecological Research, Balaton Limnological Institute, Tihany, Hungary.
authors.forename: Izabella
authors.initials: I
authors.lastname: Battonyai
authors.affiliation: Institute of Medical Chemistry, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary.
authors.forename: Csaba
authors.initials: C
authors.lastname: Hegedűs
authors.affiliation: MTA Centre for Ecological Research, Balaton Limnological Institute, Tihany, Hungary.
authors.forename: Csilla
authors.initials: C
authors.lastname: Balogh
authors.affiliation: MTA Centre for Ecological Research, Balaton Limnological Institute, Tihany, Hungary.
authors.forename: Károly
authors.initials: K
authors.lastname: Elekes
mesh_terms: D000818:Animals; D006152:Cyclic GMP / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D006372:Helix, Snails / Q000378:metabolism*; D008954:Models, Biological; D016202:N-Methylaspartate / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D009812:Odorants; D009830:Olfactory Bulb / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D016194:Receptors, N-Methyl-D-Aspartate; D009569:Nitric Oxide; D018698:Glutamic Acid; D016202:N-Methylaspartate; D006152:Cyclic GMP
keywords: AGC family kinase; Cyclic guanosine monophosphate; Glutamate; Nitric oxide; Olfaction; Procerebrum