Study of the relationship between glutamate-induced delayed calcium deregulation, mitochondrial depolarization and subsequent neuronal death

Abstract

It is known that prolonged exposure of primary neuronal cultures to toxic doses of glutamate (Glu) causes a biphasic increase in intracellular free Ca2+ concentration ([Ca2+],). The second phase o f[Ca2+]i increase (delayed calcium deregulation, DCD) occurs simultaneously with a strong mitochondrial depolarization (MD). In the present study a linear correlation between lag periods of the DCD and MD in primary cultures of rat cerebellar granule cells exposed to Glu was shown. Comparison of [Ca2+], changes induced by Glu with fluorescent images of the same neurons stained with Hoechst 33342, Syto-13 and EthD-1 following 18—20 hours after Glu insult showed that all neurons, which did not have DCD, survived. In contrast, almost all neurons (~97%, 2 out of 76) who developed DCD died by necrosis or apoptosis.