In this study we used Aβ peptide intra brain injection for induction of AD in wistar rat, and then we isolated mitochondria from brain of AD rats to figure out probable mitochondrial toxic mechanisms involved in the neuronal pathology of AD such as increased active oxygen radicals (ROS) formation, collapse of mitochondrial membrane potential and ADP/ATP ratio, mitochondrial swelling, release of cytochrome c and finally cell death signaling by caspase-3 activation. This evidence concerns the gene CYCS and Alzheimer disease.