title: Melatonin counteracts inducible mitochondrial nitric oxide synthase-dependent mitochondrial dysfunction in skeletal muscle of septic mice.
abstract: Mitochondrial nitric oxide synthase (mtNOS) produces nitric oxide (NO) to modulate mitochondrial respiration. Besides a constitutive mtNOS isoform it was recently suggested that mitochondria express an inducible isoform of the enzyme during sepsis. Thus, the mitochondrial respiratory inhibition and energy failure underlying skeletal muscle contractility failure observed in sepsis may reflect the high levels of NO produced by inducible mtNOS. The fact that mtNOS is induced during sepsis suggests its relation to inducible nitric oxide synthase (iNOS). Thus, we examined the changes in mtNOS activity and mitochondrial function in skeletal muscle of wild-type (iNOS(+/+)) and iNOS knockout (iNOS(-/-)) mice after sepsis. We also studied the effects of melatonin administration on mitochondrial damage in this experimental paradigm. After sepsis, iNOS(+/+) but no iNOS(-/-) mice showed an increase in mtNOS activity and NO production and a reduction in electron transport chain activity. These changes were accompanied by a pronounced oxidative stress reflected in changes in lipid peroxidation levels, oxidized glutathione/reduced glutathione ratio, and glutathione peroxidase and reductase activities. Melatonin treatment counteracted both the changes in mtNOS activity and rises in oxidative stress; the indole also restored mitochondrial respiratory chain in septic iNOS(+/+) mice. Mitochondria from iNOS(-/-) mice were unaffected by either sepsis or melatonin treatment. The data suggest that inducible mtNOS, which is coded by the same gene as that for iNOS, is responsible for mitochondrial dysfunction during sepsis. The results also suggest the use of melatonin for the protection against mtNOS-mediated mitochondrial failure.
authors.affiliation: Departamento de Fisiología, Instituto de Biotecnología, Universidad de Granada, Granada, Spain.
authors.forename: Germaine
authors.initials: G
authors.lastname: Escames
authors.forename: Luis C
authors.initials: LC
authors.lastname: López
authors.forename: Víctor
authors.initials: V
authors.lastname: Tapias
authors.forename: Pilar
authors.initials: P
authors.lastname: Utrilla
authors.forename: Russel J
authors.initials: RJ
authors.lastname: Reiter
authors.forename: Ana B
authors.initials: AB
authors.lastname: Hitos
authors.forename: Josefa
authors.initials: J
authors.lastname: León
authors.forename: María I
authors.initials: MI
authors.lastname: Rodríguez
authors.forename: Darío
authors.initials: D
authors.lastname: Acuña-Castroviejo
mesh_terms: D000818:Animals; D002432:Cecum / Q000473:pathology; D042967:Electron Transport Complex I / Q000378:metabolism; D042963:Electron Transport Complex II / Q000378:metabolism; D014450:Electron Transport Complex III / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D004790:Enzyme Induction; D005978:Glutathione / Q000378:metabolism; D008026:Ligation; D008550:Melatonin; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008931:Mitochondria, Muscle / Q000201:enzymology / Q000502:physiology*; D017240:Mitochondrial Myopathies / Q000209:etiology; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000201:enzymology*; D052247:Nitric Oxide Synthase Type II / Q000502:physiology*; D018384:Oxidative Stress; D018805:Sepsis / Q000150:complications / Q000503:physiopathology*
chemical_list: D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D042963:Electron Transport Complex II; D003576:Electron Transport Complex IV; D042967:Electron Transport Complex I; D014450:Electron Transport Complex III; D005978:Glutathione; D008550:Melatonin