xidative stress refers to the cytotoxic consequences of reactive oxy- O gen species (ROS) which are generated as by-products of normal or aberrant metabolic processes that utilize molecular oxygen, or changes in protection systems. Thus, generation of ROS is a part of normal life and their interaction with host defense systems appears to exert a sig- nificant influence on the normal and abnormal functioning of the cen- tral nervous system. Oxidative stress could also be a secondary conse- quence of defects in energy metabolism involving mitochondria. A subbtle shift toward the prooxidant...