title: Multiple effects of copper on NMDA receptor currents.
abstract: Copper (Cu) is an essential metal present in the human brain and released from synaptic vesicles following neuronal depolarization. Cu is known to reduce the NMDA receptor (NR) current with IC50≈20 µM. We have studied the effect of Cu on the NR current in cultured neonatal rat cerebellum granule cells (CGC) and in transiently transfected HEK293 cells (HEK), expressing either GluN1/GLUN2A or GluN1/GluN2B receptors. In CGCs, Cu causes a potentiation of the NR current at concentrations <30 µM (EC50=4.6 µM) and a block at higher concentrations (IC50=24 µM). In Fura2 loaded CGCs, Cu (≤30 µM) caused an increase of NMDA-driven calcium influx. This facilitating effect was prevented by pre-treatment with the reducing agent DTT. Cu also caused an increase of the NR current in GluN1/GluN2A receptors (EC50=2 µM) and a block at higher concentrations (IC50=26 µM). Both facilitation and inhibition were independent of voltage. The effect of Cu was quantitatively similar in GluN1/GluN2B receptors, which were potentiated by 10 µM and inhibited by 100 µM Cu. Potentiation was absent in mutants deleted of their entire amino terminal domain (ATD) of the protein, suggesting an involvement of this region in the interaction. These results indicate that Cu can facilitate the NR current at lower concentrations than those required for blocking it; this effect can have consequences on the activity of the metal at synaptic and extrasynaptic sites.
authors.affiliation: Institute of Biophysics, National Research Council, Genova, Italy. Electronic address: marchetti@ge.ibf.cnr.it.
authors.forename: Carla
authors.initials: C
authors.lastname: Marchetti
authors.affiliation: Department of Biochemistry and Medical Chemistry, Pomeranian Medical University, Szczecin, Poland.
authors.forename: Irena
authors.initials: I
authors.lastname: Baranowska-Bosiacka
authors.affiliation: Institute of Biophysics, National Research Council, Genova, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Gavazzo
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D003300:Copper / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects* / Q000235:genetics; D009474:Neurons / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics / Q000378:metabolism*; D014131:Trace Elements / Q000494:pharmacology*; D014162:Transfection
chemical_list: D002118:Calcium; D003300:Copper; D016194:Receptors, N-Methyl-D-Aspartate; D014131:Trace Elements; C121001:NR2B NMDA receptor
keywords: 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; 5,5′-dithiobis-(2-nitrobenzoic acid).; Cerebellar granule cells; Copper; DTNB; DTT; Dithiothreitol; GluN1; GluN1/GluN2A receptor; GluN1/GluN2B receptor; GluN2A; GluN2B; HEPES; N-methyl-d-aspartate; NMDA; NMDA receptor; NMDA receptor subunit 1; NMDA receptor subunit 2A; NMDA receptor subunit 2B; NR; Nickel; Redox site