Aurintricarboxylic Acid Prevents NMDA‐Mediated Excitotoxicity: Evidence for Its Action as an NMDA Receptor Antagonist

Abstract

The effect of the endonuclease inhibitor aurintricarboxylic acid (ATA) versus NMDA-mediated delayed cell death was examined in an ex vivo chick retinal preparation. Transient exposure to 100 microM NMDA for 60 min followed by a 24-h recovery period resulted in a sevenfold increase in lactate dehydrogenase (LDH) release into the medium. ATA at 100 microM significantly reduced NMDA-mediated LDH release by 60%. In clarifying the mechanism of protection versus NMDA, ATA was found to inhibit several acute NMDA-mediated effects: ATA attenuated NMDA-mediated GABA release in a dose-dependent manner (IC50 = 29.5 microM), prevented NMDA-stimulated cyclic GMP formation, and blocked NMDA-mediated 22Na+ influx. These acute inhibitory effects of ATA were overcome by increasing the NMDA concentration, which suggested a competitive interaction between NMDA and ATA. In a binding assay using membranes prepared from adult rat forebrain, ATA displaced the competitive NMDA receptor ligand [3H]CGS 19755 with an IC50 of 26.9 microM. Maximal displacement was 88% with 100 microM ATA. These studies demonstrate that ATA protected neurons from NMDA-mediated cell death upstream of endonuclease inhibition, i.e., by antagonizing NMDA receptor activity in a manner consistent with competitive antagonism.

Pathophysiology of oligodendroglial excitotoxicity

“…SD, n = 5 ) . These results suggest that kainate-induced plasma membrane damage is a consequence, rather than a cause, of DNA damage, but should be interpreted with caution, because the pharmacological actions of ATA are known not to be restricted to inhibition of endonucleases (Batistatou and Greene, 1991;Zeevalk et al, 1993;Yasuda et al, 1995).…”

Delayed application of aurintricarboxylic acid reduces glutamate‐induced cortical neuronal injury

“…The ability of ATA to block glutamate or N-methyl-D-aspartate (NMDA) neurotoxicity has been confirmed on cultured hippocampal neurons (Samples and Dubinsky, 1993), hippocampal neurons in vivo (Roberts-Lewis et al, 1993), and chick retinal neurons (Zeevalk et al, 1993). However, Dessi et al (1993) found that neither ATA nor protein synthesis inhibitors protected cerebellar granule cells against glutamate neurotoxicity .…”

“…However, Dessi et al (1993) found that neither ATA nor protein synthesis inhibitors protected cerebellar granule cells against glutamate neurotoxicity . Of further interest was the observation of Zeevalk et al (1993) that ATA is a competitive NMDA antagonist, able to displace ['HICGS 19755 with an ICs0 of 27 pM.…”

Aurintricarboxylic Acid Protects against Cell Death Caused by Lipopolysaccharide in Macrophages by Decreasing Inducible Nitric-Oxide Synthase Induction via IκB Kinase, Extracellular Signal-Regulated Kinase, and p38 Mitogen-Activated Protein Kinase Inhibition

“…After these observations, ATA was also demonstrated to act in an endonuclease-independent manner to interact with several cellular targets, which might also contribute to its antiapoptotic effects. These include the topoisomerases (Benchokroun et al, 1995), the interferon-␣ and N-methyl-D-aspartate receptors (Zeevald et al, 1993), and different important signaling cascades. For example, it is a potent activator of the mitogen-activated protein kinase (MAPK) cascade in PC-12 (Okada and Koizumi, 1995) and Nb2 lymphoma (Rui et al, 1998) cells.…”