P3–375: Lipoic acid and <i>N</i>–acetyl cysteine protect against mitochondrial–related oxidative stress in fibroblasts from Alzheimer disease patients

Recent work was begun to focus on oxidative stress events that involve a variety of cellular pathways. Indeed, there is accumulating evidence suggesting that oxidative stress occurs prior to the onset of symptoms in Alzheimer disease (AD) and such oxidative changes are pervasive throughout the body being detected peripherally as well as associated with the vulnerable regions of the brain affected in disease. The possibility that oxidative stress is a primary event in AD has led to research exploring how antioxidants in foods and supplements can prevent and/or delay onset of AD. Compare oxidative and apoptotic markers in skin fibroblasts obtained from AD, age–matched and young control subjects, at basal conditions and after pre–treatment with lipoic acid (LA) and/or N–acetyl cysteine (NAC). Furthermore, to elucidate if the oxidative levels observed were directly related with mitochondria, we induced mitochondrial dysfunction with N–methylprotoporphyrine (NMP), which inhibits cytochrome oxidase assembly. We evaluated cell viability, oxidative stress (4–hydroxy–2–nonenal, Nϵ–(carboxymethyl)lysine and heme–oxygenase–1) and apoptotic (caspase 9 and Bax) markers. Fibroblasts from patients with AD showed the highest levels of oxidative stress; additionally we observed an age–dependent increase in the levels of oxidative stress among controls. The antioxidants, LA (1mM) and/or NAC (100mM) exerted a protective effect characterized by an increase in cell viability and a decrease in oxidative stress and apoptotic markers. Furthermore, we observed that the protective effect of both agents was synergistic, i.e., the protection was higher when both agents were present simultaneously. Heme deficiency induced by NMP resulted in increased oxidative and apoptotic levels. The effect induced by NMP was reversed or attenuated by the presence of LA and NAC suggesting that these agents are reducing oxidative stress by acting on mitochondria. Our results support the view that mitochondria are key players in oxidative damage observed in AD. Furthermore, antioxidant therapies based on LA and NAC supplementation seem promising since they can prevent mitochondrial decay associated with aging and AD.