Hypoxia enhances β-amyloid-induced apoptosis in rat cultured hippocampal neurons

We investigated the effect of hypoxia on β-amyloid (Aβ)-induced apoptosis in rat cultured hippocampal neurons. Aβ (25 μM for 48 h) decreased the number of neuronal cells and increased the number of TUNEL-positive cells. Hypoxia (6 h) also decreased the number of neuronal cells, but did not increase the number of TUNEL-positive cells. Moreover, combined treatment with both Aβ and hypoxia (Aβ/hypoxia) significantly enhanced in decrease in the number of neuronal cells and the increase in the number of TUNEL-positive cells. Z-Asp-CH₂-DCB, an inhibitor of interleukin-1β-converting enzyme (ICE), or 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a non-N-methyl-D-aspartate (non-NMDA) receptor antagonist, decreased the number of TUNEL-positive cells with Aβ/hypoxia. These findings suggest that ischemia or hypoxia is an important factor that facilitates the symptoms of Alzheimer's disease and that non-NMDA receptors are involved in the induction of apoptosis in patients suffering from both cerebrovascular disease and Alzheimer's disease.