Studies on lipid peroxidation and protein oxidation in the aging brain

Lipid peroxidation (LP) and protein oxidation (PO) were investigated in hippocampus and frontal cortex homogenates from young (5 months), mature (13 months) and old (24 months) Wistar rats and young (5 months) and old (24 months) Brown Norway rats. LP and PO were determined in basal conditions and after incubation without iron (spontaneous condition) or with iron (stimulated condition). LP was measured as HPLC-assayed malondialdehyde (MDA) and PO as protein carbonyl (CO) content. Brain homogenates formed considerable amounts of MDA and CO spontaneously and, to an even greater extent, in the presence of Fe2+. Old rats showed greater iron-stimulated LP in the cortex than young rats, but the difference was not significant. Basal (but not spontaneous or stimulated) PO was significantly increased (19%) in the hippocampus of old compared to young rats. This study does not confirm the age-related increase in LP reported in the literature and only partially confirms the findings concerning PO.