Age-related deficiencies in complex I endogenous substrate availability and reserve capacity of complex IV in cortical neuron electron transport.
Respiratory enzyme complex dysfunction is mechanistically involved in mitochondrial failure leading to neurodegenerative disease, but the pathway is unclear. Here, age-related differences in mitochondrial respiration were measured in both whole and permeabilized neurons from 9-month and 24-month adult rat cortex cultured in common conditions. After permeabilization, respiration increased in both ages of neurons with excess substrates. To dissect specific deficiencies in the respiratory chain, inhibitors for each respiratory chain complex were used to isolate their contributions. Relative to neurons from 9-month rats, in neurons isolated from 24-month rats, complexes I, III, and IV were more sensitive to selective inhibition. Flux control point analysis identified complex I in neurons isolated from 24-month rats as the most sensitive to endogenous substrate availability. The greatest age-related deficit in flux capacity occurred at complex IV with a 29% decrease in neurons isolated from 24-month rats relative to those from 9-month rats. The deficits in complexes I and III may contribute to a redox shift in the quinone pool within the electron transport chain, further extending these age-related deficits. Together these changes could lead to an age-related catastrophic decline in energy production and neuronal death.
Department of Medical Microbiology, Immunology, and Cell Biology, Southern Illinois University School of Medicine, PO Box 19626, Springfield, IL 62794-9626, USA.
Torrie T
TT
Jones
Gregory J
GJ
Brewer
D000818:Animals; D002463:Cell Membrane Permeability; D019069:Cell Respiration; D016922:Cellular Senescence / Q000502:physiology*; D002540:Cerebral Cortex / Q000166:cytology / Q000201:enzymology*; D004579:Electron Transport / Q000502:physiology*; D042967:Electron Transport Complex I / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000378:metabolism*; D004734:Energy Metabolism; D008297:Male; D009474:Neurons / Q000166:cytology / Q000201:enzymology*; D051381:Rats; D017208:Rats, Wistar; D013379:Substrate Specificity
D003576:Electron Transport Complex IV; D042967:Electron Transport Complex I