Advanced glycation endproducts change glutathione redox status in SH-SY5Y human neuroblastoma cells by a hydrogen peroxide dependent mechanism

The reaction of proteins with reducing sugars leads to the formation of 'advanced glycation endproducts' (AGEs). They accumulate in Alzheimer's disease brain in the vicinity of β-amyloid plaques. AGEs are cytotoxic by a mechanism involving reactive oxygen species, which implies that they could compromise glutathione redox status. In this study, we show that AGEs (BSA-AGE and β-amyloid-AGE) persistently increase the ratio of oxidized to reduced glutathione in a dose- and time-dependent manner in SH-SY5Y neuroblastoma cells. The level of oxidized glutathione accounted to 10-14% and persisted for up to 24 h in the presence of added AGEs. In contrast, the unmodified β-amyloid peptides Aβ (1-40) and Aβ (25-35) had no significant effect on glutathione redox status. The AGE-induced increase in oxidized glutathione could be prevented by the radical scavengers N-acetylcysteine, α-lipoic acid and 17β-estradiol or by application of catalase, indicating that superoxide and hydrogen peroxide production precedes the AGE-mediated depletion of reduced glutathione.