title: Cytochrome c oxidase is decreased in Alzheimer's disease platelets.
abstract: Cytochrome c oxidase (COX) activity reportedly is reduced in Alzheimer's disease (AD) brain and platelets. The reasons for the defect in either tissue are unknown, but its presence in a non-degenerating tissue suggests it is not simply a consequence of neurodegeneration. We now offer confirmation of the AD platelet COX defect. Compared to age-matched controls, in mitochondria isolated from AD platelets there was a 15% decrease in COX activity despite the fact that COX subunits were present at normal levels. Platelet ATP levels were diminished in AD (from 11.33 +/- 0.52 to 9.11 +/- 0.72 nmol/mg), while reactive oxygen species (ROS) were increased (from 97.03 +/- 25.9 to 338.3 +/- 100 K/mg). Platelet membrane fluidity, Vitamin E, and cholesterol content were similar between groups. We conclude that COX catalytic activity is indeed diminished in AD platelet mitochondria, does not result from altered membrane fluidity, and is associated with ROS overproduction and ATP under-production.
authors.affiliation: Faculty of Medicine, Center for Neuroscience of Coimbra, University of Coimbra, 3004 517, Portugal.
authors.forename: Sandra Morais
authors.initials: SM
authors.lastname: Cardoso
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Proença
authors.forename: Sancha
authors.initials: S
authors.lastname: Santos
authors.forename: Isabel
authors.initials: I
authors.lastname: Santana
authors.forename: Catarina R
authors.initials: CR
authors.lastname: Oliveira
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000097:blood; D017668:Age of Onset; D000368:Aged; D000544:Alzheimer Disease / Q000097:blood* / Q000201:enzymology; D001792:Blood Platelets / Q000201:enzymology*; D016022:Case-Control Studies; D002784:Cholesterol / Q000097:blood; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002950:Citrate (si)-Synthase / Q000378:metabolism; D042967:Electron Transport Complex I / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000097:blood*; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D005609:Free Radicals / Q000097:blood; D006801:Humans; D008875:Middle Aged; D008928:Mitochondria / Q000201:enzymology; D009249:NADP / Q000378:metabolism; D013384:Succinate Cytochrome c Oxidoreductase / Q000378:metabolism; D014810:Vitamin E / Q000097:blood
chemical_list: D000227:Adenine Nucleotides; D005609:Free Radicals; D014810:Vitamin E; D009249:NADP; D000255:Adenosine Triphosphate; D002784:Cholesterol; D013384:Succinate Cytochrome c Oxidoreductase; D003576:Electron Transport Complex IV; D002950:Citrate (si)-Synthase; D042967:Electron Transport Complex I