A vicious circle: role of oxidative stress, intraneuronal Abeta and Cu in Alzheimer's disease.

Recent evidence indicates that both intraneuronal Abeta and Cu are involved in the pathological processes in Alzheimer's disease (AD). This perspective shows a possible interrelation of these factors. AbetaPP, the precursor of Abeta which represents the main constituent of amyloid plaques, is involved in Cu homeostasis in mammals. In vitro observations and in vivo data obtained from AbetaPP mouse models provide strong evidence that AbetaPP and the resulting Abeta overproduction facilitate intracellular Cu to leave the cell. An increased Cu efflux seems to lead to Cu deficiency and, subsequently, reduced SOD-1 activity. The Cu-dependent SOD-1 activity is the main enzyme involved in detoxifying free radicals. Several reports have shown that oxidative stress is an invariable age-dependent feature in the brain of AD patients. Increased oxidative stress leads to an increase in intraneuronal Abeta accumulation, which has been shown to be the main trigger for neuronal loss in transgenic mouse models. Thus, we conclude that bioavailability of Cu is a crucial point for the pathogenesis of AD.