Protection of cortical neurons against oxygen-glucose deprivation and N-methyl- d-aspartate by DIDS and SITS

Abstract

The Cl − channel blockers, 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS) or 4-acetamido-4′-isothiocyanatostilbene-2,2′-disulfonic acid (SITS) dose-dependently protected against oxygen-glucose deprivation in cultured rat cortical neurons. DIDS or SITS attenuated oxygen-glucose deprivation-induced increases in extracellular glutamate concentrations and intracellular Ca 2+. DIDS or SITS provided moderate protection against N-methyl- d-aspartate (NMDA) toxicity and decreased NMDA receptor-mediated increases in intracellular Ca 2+. Whole-cell NMDA receptor currents were attenuated 39±2% and 21±3% by 1 mM DIDS and SITS, respectively. Other Cl − channel blockers as equipotent as DIDS and SITS did not decrease oxygen-glucose deprivation- or NMDA-mediated neuronal Ca 2+ influx or toxicity. Neurotoxicity by exogenous glutamate was not prevented by SITS and was exacerbated by DIDS. Reductions in oxygen-glucose deprivation-induced increases in intracellular Ca 2+ levels underlie neuroprotection by DIDS and SITS. This was a reflection of lower extracellular [glutamate], direct inhibition of Ca 2+ influx through postsynaptic NMDA receptors, and possibly through other protective properties associated with DIDS and SITS.