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 beta-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 beta-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 beta-amyloid peptides A beta (1-40) and A beta (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, alpha-lipoic acid and 17beta-estradiol or by application of catalase, indicating that superoxide and hydrogen peroxide production precedes the AGE-mediated depletion of reduced glutathione.