Regulation of the NMDA receptor by redox phenomena: inhibitory role of ascorbate.

Redox phenomena seem to modulate activity of the N-methyl-D-aspartate receptor. Some reductants (ascorbate, hydroquinone) inhibit, while others (dithiothreitol, mercaptoethanol, penicillamine) potentiate NMDA receptor function. Ascorbate inhibits binding of [3H]glutamate and [3H]thienylcycohexylpiperidine to the NMDA receptor complex, and impedes NMDA-gated currents in isolated neurons; dithiothreitol-like reductants enhance NMDA-induced currents. The ability of reductants to alter function of the NMDA receptor is abolished by oxidation.