title: Unique ionotropic receptors for D-aspartate are a target for serotonin-induced synaptic plasticity in Aplysia californica.
abstract: The non-L-glutamate (L-Glu) receptor component of D-aspartate (D-Asp) currents in Aplysia californica buccal S cluster (BSC) neurons was studied with whole cell voltage clamp to differentiate it from receptors activated by other well-known agonists of the Aplysia nervous system and investigate modulatory mechanisms of D-Asp currents associated with synaptic plasticity. Acetylcholine (ACh) and serotonin (5-HT) activated whole cell excitatory currents with similar current voltage relationships to D-Asp. These currents, however, were pharmacologically distinct from D-Asp. ACh currents were blocked by hexamethonium (C6) and tubocurarine (D-TC), while D-Asp currents were unaffected. 5-HT currents were blocked by granisetron and methysergide (MES), while D-Asp currents were unaffected. Conversely, while (2S,3R)-1-(Phenanthren-2-carbonyl)piperazine-2,3-dicarboxylic acid(PPDA) blocked D-Asp currents, it had no effect on ACh or 5-HT currents. Comparison of the charge area described by currents induced by ACh or 5-HT separately from, or with, D-Asp suggests activation of distinct receptors by all 3 agonists. Charge area comparisons with L-Glu, however, suggested some overlap between L-Glu and D-Asp receptors. Ten minute exposure to 5-HT induced facilitation of D-Asp-evoked responses in BSC neurons. This effect was mimicked by phorbol ester, suggesting that protein kinase C (PKC) was involved.
authors.affiliation: University of Miami Rosenstiel School of Marine and Atmospheric Science, Division of Marine Biology and Fisheries, Miami, FL 33149, USA.
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Carlson
authors.forename: Lynne A
authors.initials: LA
authors.lastname: Fieber
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001048:Aplysia / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D026603:D-Aspartic Acid / Q000378:metabolism / Q000494:pharmacology*; D003979:Diazonium Compounds / Q000494:pharmacology; D017952:Ganglia, Invertebrate / Q000187:drug effects / Q000378:metabolism; D018698:Glutamic Acid / Q000494:pharmacology; D018738:Hexamethonium / Q000494:pharmacology; D009424:Nervous System Physiological Phenomena; D009474:Neurons / Q000187:drug effects; D018408:Patch-Clamp Techniques; D011725:Pyridines / Q000494:pharmacology; D058468:Receptors, Ionotropic Glutamate / Q000378:metabolism* / Q000502:physiology; D012701:Serotonin / Q000494:pharmacology*; D009435:Synaptic Transmission; D014403:Tubocurarine / Q000494:pharmacology
chemical_list: D003979:Diazonium Compounds; D011725:Pyridines; D058468:Receptors, Ionotropic Glutamate; C056729:4-(2'-pyridyldithio)benzyldiazoacetate; D012701:Serotonin; D018738:Hexamethonium; D018698:Glutamic Acid; D026603:D-Aspartic Acid; D000109:Acetylcholine; D014403:Tubocurarine