Synthesis, accumulation, and release of d‐aspartate in the Aplysia californica CNS

A Novel Pyridoxal 5′-Phosphate-dependent Amino Acid Racemase in the Aplysia californica Central Nervous System

“…Using CE-LIF we measured the presence of D-Ser and D-Asp in the cells containing the enzyme to determine if they co-localize. It is particularly telling that the enzyme was present in the F-, C-, and G-clusters where high levels of D-Asp content were previously reported (21,24); we now confirm the co-localization of D-Ser and D-Asp in these structures. The correlation of DAR1 and its products supports our determination that the enzyme is involved in the actual biosynthesis of D-Asp and D-Ser.…”

Physiological evidence that d-aspartate activates a current distinct from ionotropic glutamate receptor currents in Aplysia californica neurons

“…D-Asp undergoes a transient increase in concentration in the central nervous system (CNS) during embryonic development in vertebrates, and then these levels rapidly decrease postnatally due to a rise in the concentration of D-aspartate oxidase (Furuchi and Homma 2005). Although there has been considerable research on an endocrine role for D-Asp (D'Aniello 2007), there has been less exploration of a possible neurotransmitter or neuromodulatory role, despite its presence and the machinery for its synthesis, release, uptake, and breakdown in nervous tissue of a variety of organisms (D'Aniello 2007;Homma 2007;Kim et al 2010;Savage et al 2001;Scanlan et al 2010;Waagepetersen et al 2001;Wang et al 2011;Wolosker et al 2000;Yamada et al 2006) and in neuronal processes of Aplysia (Miao et al 2005;Spinelli et al 2006). Yet to be demonstrated is the physiological and molecular description of the ion channels activated by D-Asp. Owing to their structural similarity, D-Asp and L-Glu both purportedly activate ionotropic glutamate receptors (Huang et al 2005;Kiskin et al 1990;Olverman et al 1988).…”

“…The goal of this study was to provide an electrophysiological characterization of D-Asp-activated currents in S cluster neurons of the buccal ganglion (BSC), describing the electrophysiological properties of D-Asp current responses and comparisons to L-Glu-activated currents. BSC cells show a relatively high preponderance of responses to D-Asp and are innervated (Jahan-Parwar and Fredman 1976) by neurons believed to contain D-Asp due to high D-Asp racemase immunoreactivity (Scanlan et al 2010;Wang et al 2011).…”

Small-Volume Analysis of Cell–Cell Signaling Molecules in the Brain

“…Here, we outline several approaches that have worked well for assessing concentration changes in the smallest samples of brain tissues. The combination of CE-LIF, radioisotope labeling and radionuclide detection has been successfully applied to demonstrate synthesis, accumulation, and release of D-aspartate in neurons (Scanlan et al, 2010). The quantitation of biogenic amines has been performed by MEKC with electrochemical detection (Berglund et al, 2013).…”