Astrocyte-derived nitric oxide causes both reversible and irreversible damage to the neuronal mitochondrial respiratory chain.
Cytokine-stimulated astrocytes produce nitric oxide (NO), which, along with its metabolite peroxynitrite (ONOO(-)), can inhibit components of the mitochondrial respiratory chain. We used astrocytes as a source of NO/ONOO(-) and monitored the effects on neurons in coculture. We previously demonstrated that astrocytic NO/ONOO(-) causes significant damage to the activities of complexes II/III and IV of neighbouring neurons after a 24-h coculture. Under these conditions, no neuronal death was observed. Using polytetrafluoroethane filters, which are permeable to gases such as NO but impermeable to NO derivatives, we have now demonstrated that astrocyte-derived NO is responsible for the damage observed in our coculture system. Expanding on these observations, we have now shown that 24 h after removal of NO-producing astrocytes, neurons exhibit complete recovery of complex II/III and IV activities. Furthermore, extending the period of exposure of neurons to NO-producing astrocytes does not cause further damage to the neuronal mitochondrial respiratory chain. However, whereas the activity of complex II/III recovers with time, the damage to complex IV caused by a 48-h coculture with NO-producing astrocytes is irreversible. Therefore, it appears that neurons can recover from short-term damage to mitochondrial complex II/III and IV, whereas exposure to astrocytic-derived NO for longer periods causes permanent damage to neuronal complex IV.
Stewart
V C
VC
Department of Neurochemistry, Institute of Neurology, University College London, England. V.Stewart@ion.ucl.ac.uk
Sharpe
M A
MA
Clark
J B
JB
Heales
S J
SJ
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000166:cytology / Q000502:physiology*; D002470:Cell Survival; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000502:physiology; D002950:Citrate (si)-Synthase / Q000378:metabolism; D018920:Coculture Techniques; D042963:Electron Transport Complex II; D014450:Electron Transport Complex III / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D007700:Kinetics; D008928:Mitochondria / Q000502:physiology*; D009097:Multienzyme Complexes / Q000378:metabolism; D009245:NADH Dehydrogenase / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D009566:Nitrates / Q000502:physiology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D016877:Oxidants; D010088:Oxidoreductases / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013385:Succinate Dehydrogenase / Q000378:metabolism
D009097:Multienzyme Complexes; D009566:Nitrates; D016877:Oxidants; C039642:peroxynitric acid; D009569:Nitric Oxide; D010088:Oxidoreductases; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase; D009245:NADH Dehydrogenase; D003576:Electron Transport Complex IV; D002950:Citrate (si)-Synthase; D014450:Electron Transport Complex III