title: Decreased platelet cytochrome c oxidase activity is accompanied by increased blood lactate concentration during exercise in patients with Alzheimer disease.
abstract: Increasing evidence indicates that mitochondrial dysfunction occurs in the central nervous system as well as in the peripheral tissues from Alzheimer's disease (AD) patients. We have recently shown that mitochondrial cytochrome c oxidase (COX) activity is significantly reduced in brain and platelets from AD patients compared to controls. In the present study we investigated whether impaired COX activity could have functional consequences on energy metabolism. Blood lactate concentration was monitored at rest and during incremental exercise in 22 AD patients in whom COX activity in platelets was decreased compared to controls (35.7 +/- 11.4 vs 48.4 +/- 1.4 nmol/min/mg, P < 0.01). In both resting and exercising conditions, blood lactate was significantly higher in AD patients than in controls. Although the magnitude of exercise-related lactate accumulation was not different between the two groups, an anticipated anaerobic lactate threshold during the incremental forearm exercise was found in AD patients (50% of maximal voluntary contraction MVC compared to 60% in controls). COX activity was inversely related to lactate at a significant level for resting condition (r = -0.65) and borderline for anaerobic threshold exercise level. These results support the hypothesis of a systemic impairment of the mitochondrial function in AD and indicate that decreased COX activity could have functional consequences on metabolism.
authors.affiliation: Department of Neurosciences, Neurological Clinics, University of Pisa, Via Roma 67, 56126, Pisa, Italy. mmancuso@inwind.it
authors.forename: Michelangelo
authors.initials: M
authors.lastname: Mancuso
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Filosto
authors.forename: Francesca
authors.initials: F
authors.lastname: Bosetti
authors.forename: Roberto
authors.initials: R
authors.lastname: Ceravolo
authors.forename: Anna
authors.initials: A
authors.lastname: Rocchi
authors.forename: Gloria
authors.initials: G
authors.lastname: Tognoni
authors.forename: Maria Laura
authors.initials: ML
authors.lastname: Manca
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Solaini
authors.forename: Gabriele
authors.initials: G
authors.lastname: Siciliano
authors.forename: Luigi
authors.initials: L
authors.lastname: Murri
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000503:physiopathology*; D001792:Blood Platelets / Q000201:enzymology*; D003576:Electron Transport Complex IV / Q000378:metabolism*; D004734:Energy Metabolism; D005080:Exercise Test; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000201:enzymology; D009483:Neuropsychological Tests; D005082:Physical Exertion; D012016:Reference Values
chemical_list: D019344:Lactic Acid; D003576:Electron Transport Complex IV