Survival factor-insensitive generation of reactive oxygen species induced by serum deprivation in neuronal cells

To investigate the involvement of reactive oxygen species (ROS) in neuronal apoptosis, we performed confocal and flow cytometric analysis with a ROS-specific fluorogen, 6-carboxy-2', 7'-dichorodihydrofluorescein diacetate, di(acetoxymethyl ester) (C-DCDHF-DA). Serum deprivation significantly increased the level of ROS in PC12 cells and rat cortical neurons. N,N'-diphenyl-p-phenylenediamine (DPPD), an antioxidant, reduced ROS production induced by serum deprivation and recovered cell survival. However, some survival factors such as nerve growth factor and Bcl-2, which prevented the apoptosis of PC12 cells, did not affect the up-regulation of ROS induced by serum deprivation. Epidermal growth factor which prevented the apoptosis of cortical neurons, did not affect the increase of ROS. These data suggest that survival factors rescue the serum deprivation induced apoptosis independently of ROS production.