Characterization of 8-epiprostaglandin F-2 alpha as a marker of amyloid beta-peptide-induced oxidative damage

The amyloid beta-peptide (A beta) is a major component of the neuritic plaq ues that are a defining histological characteristic of Alzheimer's disease. A beta can be directly toxic and pro-inflammatory to cells in vitro. Numer ous reports have shown that oxidative damage and reactive oxygen species pl ay a role in A beta-mediated neurotoxicity. 8-Epiprostaglandin F-2 alpha (8 -isoprostane) is a well characterized product of lipid peroxidation that is formed nonenzymatically in cell membranes following an oxidative insult. W e report a time- and concentration-dependent increase in 8-isoprostane leve ls in rat hippocampal cultures treated with A beta(1-40) or hydrogen peroxi de. As evidence that 8-isoprostane production is part of an A beta toxic pa thway, alkaline-treated peptide, which shows minimal toxic activity, result ed in greatly attenuated 8-isoprostane production. Although the increase in 8-isoprostane levels preceded cell death, exogenously added 8-isoprostane had no cytotoxic effects. The antioxidants vitamin E and propyl gallate att enuated A beta-induced 8-isoprostane formation yet had no effect on A beta- induced lactate dehydrogenase release. Neither vitamin E nor propyl gallate had any effect on A beta's ability to adopt a beta-pleated sheet structure and deposit on cells as determined by thioflavine S fluorescence. We concl ude that 8-isoprostane is an indicator of A beta-induced damage but not nec essarily a mediator of A beta-induced neurotoxicity, Also, 8-isoprostane co uld be a useful marker for assessing oxidative damage in the CNS.