Effects of pyrroloquinoline quinone on glutamate-induced production of reactive oxygen species in neurons

Eur J Pharmacol. 1997 May 12;326(1):67-74. doi: 10.1016/s0014-2999(97)00137-4.


Pyrroloquinoline quinone may act as a free radical scavenger and also as a modulator of the NMDA receptor associated redox modulatory site. Using the oxidation sensitive dye dihydroethidium, we examined the effects of pyrroloquinoline quinone on free radical production in cultured forebrain neurons following glutamate receptor activation. Both glutamate (100 microM) and hydrogen peroxide (30 mM) produced a rapid increase in dihydroethidium fluorescence indicating dye oxidation. Pyrroloquinoline quinone (5-200 microM) effectively inhibited dihydroethidium fluorescence induced by glutamate but not by hydrogen peroxide. Glutamate-induced dihydroethidium fluorescence was inhibited by the thiol oxidant 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB). Pyrroloquinoline quinone (50 microM) inhibited glutamate responses in control and in dithiothreitol treated neurons. However, pyrroloquinoline quinone did not further decrease the response to glutamate in DTNB treated neurons. These results suggest that pyrroloquinoline quinone inhibits the free radical-generating response to glutamate by oxidizing the NMDA receptor redox site and not by scavenging reactive oxygen species.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Excitatory Amino Acid Antagonists / pharmacology*
  • Free Radical Scavengers / pharmacology*
  • Glutamic Acid / pharmacology*
  • Hydrogen Peroxide / metabolism
  • Microscopy, Fluorescence
  • Neurons / drug effects
  • Neurons / metabolism*
  • Neuroprotective Agents / pharmacology*
  • Oxidants / metabolism
  • Oxidation-Reduction
  • PQQ Cofactor
  • Quinolones / pharmacology*
  • Rats
  • Rats, Sprague-Dawley
  • Reactive Oxygen Species / metabolism*
  • Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors
  • Receptors, N-Methyl-D-Aspartate / drug effects


  • Excitatory Amino Acid Antagonists
  • Free Radical Scavengers
  • Neuroprotective Agents
  • Oxidants
  • Quinolones
  • Reactive Oxygen Species
  • Receptors, N-Methyl-D-Aspartate
  • Glutamic Acid
  • PQQ Cofactor
  • Hydrogen Peroxide