Beside the use of H2O2 in some initial experiments, we usually induced oxidative stress by the NO donor sodium nitroprusside (SNP), due to the important role of nitrosative stress in AD (Keil et al., 2004a,b). In PC12 cells, SNP, led to a reduction of MMP and ATP levels. Under basal conditions without additional SNP damage, piracetam did not affect both alterations even at rather high concentrations. However, piracetam was able to reduce both measures of mitochondrial dysfunction after pre- and post-incubation (Keil et al., 2006).