An N-methyl-D-aspartate receptor channel blocker with neuroprotective activity.
Excitotoxicity, resulting from sustained activation of glutamate receptors of the N-methyl-d-aspartate (NMDA) subtype, is considered to play a causative role in the etiology of ischemic stroke and several neurodegenerative diseases. The NMDA receptor is therefore a target for the development of neuroprotective agents. Here, we identify an N-benzylated triamine (denoted as NBTA) as a highly selective and potent NMDA-receptor channel blocker selected by screening a reduced dipeptidomimetic synthetic combinatorial library. NBTA blocks recombinant NMDA receptors expressed in Xenopus laevis oocytes with a mean IC(50) of 80 nM; in contrast, it does not block GluR1, a glutamate receptor of the non-NMDA subtype. The blocking activity of NBTA on NMDA receptors exhibits the characteristics of an open-channel blocker: (i) no competition with agonists, (ii) voltage dependence, and (iii) use dependence. Significantly, NBTA protects rodent hippocampal neurons from NMDA receptor, but not kainate receptor-mediated excitotoxic cell death, in agreement with its selective action on the corresponding recombinant receptors. Mutagenesis data indicate that the N site, a key asparagine on the M2 transmembrane segment of the NR1 subunit, is the main determinant of the blocker action. The results highlight the potential of this compound as a neuroprotectant.
Tai
K K
KK
Section of Neurobiology, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0366, USA.
Blondelle
S E
SE
Ostresh
J M
JM
Houghten
R A
RA
Montal
M
M
D000588:Amines / Q000494:pharmacology*; D000818:Animals; D016923:Cell Death; D002478:Cells, Cultured; D005260:Female; D006624:Hippocampus / Q000166:cytology; D009474:Neurons / Q000166:cytology / Q000187:drug effects*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors* / Q000235:genetics; D014982:Xenopus laevis
D000588:Amines; C438205:N-benzylated triamine; D018696:Neuroprotective Agents; D016194:Receptors, N-Methyl-D-Aspartate