Modulation of an AMPA-like glutamate receptor (SqGluR) gating by L- and D-aspartic acids.
L- and D-aspartic acids (L-Asp and D-Asp) are present in the majority of nervous systems. In phylogeny, significant levels have been reported in mollusc brains, particularly cephalopods. To examine the role of L- and D-Asp on a cephalopod receptor, we studied ligand gating of a squid glutamate receptor (SqGluR) expressed in HEK 239 (human embryonic kidney) cells. Under voltage clamp, application of L-glutamate (L-Glu; 1-30 mM), but not D-glutamate (D-Glu), or L- or D-Asp, evoked an inward current of 0.1 nA. L- or D-Asp (200 microM) applied with 20 mM L-Glu, slowed the time course of activation and inactivation of the L-Glu gated current (time constant increased from 1 s (L-Glu alone) to 3 s (D-Asp and L-Glu) and to 19 s (L-Asp and L-Glu)). Our results suggest that in molluscan systems, aspartic acid could act as a neuromodulator during glutamatergic transmission and could significantly alter synaptic integration by slowing glutamate receptor gating.
Brown
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ER
Neurobiology Laboratory, Stazione Zoologica Anton Dohrn, Naples, Italy. brown@szn.it
Piscopo
S
S
Chun
J-T
JT
Francone
M
M
Mirabile
I
I
D'Aniello
A
A
D000818:Animals; D002460:Cell Line; D049830:Cephalopoda / Q000235:genetics / Q000378:metabolism*; D026603:D-Aspartic Acid / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D018698:Glutamic Acid / Q000494:pharmacology; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects* / Q000502:physiology; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D018091:Receptors, AMPA / Q000235:genetics / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects* / Q000502:physiology
D018377:Neurotransmitter Agents; D018091:Receptors, AMPA; D018698:Glutamic Acid; D026603:D-Aspartic Acid