Pyruvate protection against beta-amyloid-induced neuronal death: role of mitochondrial redox state.
The mechanism by which beta-amyloid protein (A beta) causes degeneration in cultured neurons is not completely understood, but several lines of evidence suggest that A beta-mediated neuronal death is associated with an enhanced production of reactive oxygen species (ROS) and oxidative damage. In the present study, we address whether supplementation of glucose-containing culture media with energy substrates, pyruvate plus malate (P/M), protects rat primary neurons from A beta-induced degeneration and death. We found that P/M addition attenuated cell death evoked by beta-amyloid peptides (A beta(25-35) and A beta(1-40)) after 24 hr treatment and that this effect was blocked by alpha-ciano-3-hydroxycinnamate (CIN), suggesting that it requires mitochondrial pyruvate uptake. P/M supply to control and A beta-treated neuronal cultures increases cellular reducing power, as indicated by the ability to reduce the dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The early increases in ROS levels, measured by dichlorofluorescein (DCF) fluorescence, and caspase-3 activity that follow exposure to A beta were notably reduced in the presence of P/M. These results place activation of caspase-3 most likely downstream of oxidative damage to the mitochondria and indicate that mitochondrial NAD(P) redox status plays a central role in the neuroprotective effect of pyruvate. Inhibition of respiratory chain complexes and mitochondrial uncoupling did not block the early increase in ROS levels, suggesting that A beta could initiate oxidative stress by activating a source of ROS that is not accesible to the antioxidant defenses fueled by mitochondrial substrates.
Alvarez
Gema
G
Centro de Biología Molecular "Severo Ochoa," CSIC-Universidad Autónoma de Madrid, Madrid, Spain.
Ramos
Milagros
M
Ruiz
Francisca
F
Satrústegui
Jorgina
J
Bogónez
Elena
E
D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D000818:Animals; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D019610:Cytoprotection / Q000187:drug effects* / Q000502:physiology; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D010084:Oxidation-Reduction / Q000187:drug effects; D019289:Pyruvic Acid / Q000494:pharmacology*; D051381:Rats
D016229:Amyloid beta-Peptides; D019289:Pyruvic Acid