Age-related changes in H2O2 production and bioenergetics in rat brain synaptosomes.
Detrimental changes to mitochondrial function have been shown to occur with age. In this study we examined the levels of H(2)O(2) production, in situ mitochondrial membrane potential (Deltapsi(m)), oxygen consumption (JO(2)) and electron transport chain (ETC) enzyme activities in synaptosomes isolated from rats of two age groups, 6 and 18 months. The rate of H(2)O(2) production in synaptosomes was found to be higher in the 18-month old group compared to that of 6-month old. Deltapsi(m) was found to be significantly lower in synaptosomes from the older rats, which also correlated with a reduction in JO(2). Measurement of the individual electron transport chain enzyme activities revealed that reduced complex II/III and complex IV activities were the possible contributors to the reduced bioenergetic function in synaptosomes from the older rats. These data suggest that ageing may lead to increased nerve terminal H(2)O(2) production while simultaneous deleterious effects on bioenergetic function occur in in situ synaptosomal mitochondria. In addition, Ca(2+)-independent glutamate release was found to be increased at lower levels of complex I inhibition in the synaptosomes from older rats, suggesting that reduction of mitochondrial function may potentiate excitotoxic conditions in the ageing brain.
School of Biochemistry and Immunology and Trinity College Institute of Neuroscience, Trinity College Dublin, Ireland.
Seán M
SM
Kilbride
Jayne E
JE
Telford
Gavin P
GP
Davey
D000255:Adenosine Triphosphate / Q000378:metabolism; D000375:Aging / Q000502:physiology*; D000818:Animals; D001921:Brain / Q000254:growth & development* / Q000378:metabolism*; D004579:Electron Transport; D018698:Glutamic Acid / Q000378:metabolism; D006706:Homeostasis; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008564:Membrane Potentials; D008928:Mitochondria / Q000378:metabolism*; D051381:Rats; D013367:Submitochondrial Particles / Q000502:physiology; D013574:Synaptosomes / Q000378:metabolism*
D018698:Glutamic Acid; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide