Temperature-dependent N-methyl-D-aspartate receptor-mediated cytotoxicity in cultured rat cortical neurons

Hypothermia protects against hypoxic or ischemic damage. However, the mechanisms by which brain cooling prevents hypoxic or ischemic damage are not clear. We examined whether hypothermia protects against excitotoxicity in cultured cortical cells. Exposure of cortical cell culture to 500 microM N-methyl-D-aspartate (NMDA) for 15 min at 32 degrees C or 37 degrees C did not induce neurotoxicity. On the other hand, reduction of temperature to 20 degrees C resulted in widespread neuronal disintegration by the following day. Moreover, intracellular calcium concentration increased markedly by adding NMDA to cells at 20 degrees C. These results suggest that profound hypothermia does not protect neurons from excitotoxicity by inhibiting NMDA receptor activity.