Amyloid peptide enhances nail rusting: novel insight into mechanisms of aging and Alzheimer’s disease

Oxidative stress is believed to play a major role in the dysfunction and degeneration of neurons that occurs in Alzheimer’s disease (AD). Amyloid β-peptide forms insoluble aggregates in the brains of AD patients and it has been shown that the neurotoxic actions of amyloid β-peptide involve membrane lipid peroxidation. However, it is not known how amyloid β-peptide induces oxidative stress. Here we describe a simple experiment that we performed 6 years ago that demonstrates that amyloid β-peptide is itself a source of oxyradicals. The weights of iron nails were recorded and the nails were then incubated in one of three different solutions: water (control), 1 mM amyloid β-peptide (1–40) in water, and 1 mM bovine serum albumin in water. After 1 month of incubation the nails were then removed, allowed to dry, and then their weights determined. The weights of all the nails decreased, but the amount of weight decrease in the nails that had been incubated in the presence of amyloid β-peptide was approximately twice that of the nails incubated in the control solutions. These data provide direct evidence that amyloid β-peptide generates, or facilitates the production of, oxyradicals thereby enhancing metal oxidation.