ABSTRACT
Although it is known that neuronal cell death during development occurs by apoptosis, the mechanisms underlying excitatory amino acid-induced neuronal cell death remain poorly understood. In this study we have examined the mechanism by which L-glutamate, an excitatory amino acid neurotransmitter, induces cell death in PC12 cell lines. To characterize cell death, we employed sandwich enzyme-linked immunosorbent assay (ELISA) method for cellular DNA fragmentation, DNA agarose gel electrophoresis and chromatin staining by acridine orange and ethidium bromide after treating the PC12 cells with L-glutamate. L-Glutamate caused dose-dependent cell death with a maximum at 24 hrs after the treatment. These cellular fragmentation was blocked by pretreatment of MK-801, a noncompetitive N-methyl-D-aspartic acid (NMDA) receptor antagonist, and nerve growth factor(NGF). Analysis of DNA integrity from L-glutamate-treated cells revealed cleavage of DNA into regular sized fragments, a biochemical hallmark of apoptosis. The PC12 cells that were induced to die by L-glutamate treatment exhibited classical chromatin condensation under the light microscopy after acridine orange and ethidium bromide staining. These results suggest that apoptosis is one of the key features that are involved in L-glutamate-induced excitotoxic cell death in PC12 cells, and these cell death are mediated by NMDA receptor and depend on NGF.