Identification of an inducible nitric oxide synthase in diaphragm mitochondria from septic mice: its relation with mitochondrial dysfunction and prevention by melatonin.

Abstract

Sepsis provokes an induction of inducible nitric oxide synthase (iNOS) and melatonin down-regulates its expression and activity. Looking for an inducible mtNOS isoform, we induced sepsis by cecal ligation and puncture in both normal and iNOS knockout mice and studied the changes in mtNOS activity. We also studied the effects of mtNOS induction in mitochondrial function, and the role of melatonin against induced mtNOS and mitochondrial dysfunction. The activity of mtNOS and nitrite levels significantly increased after sepsis in iNOS+/+ mice. These animals showed a significant inhibition of the respiratory chain activity and an increase in mitochondrial oxidative stress, reflected in the disulfide/glutathione ratio, glutathione redox cycling enzymes activity and lipid peroxidation levels. Interestingly, mtNOS activity remained unchanged in iNOS-/- septic mice, and mitochondria of these animals were unaffected by sepsis. Melatonin administration to iNOS+/+ mice counteracted mtNOS induction and respiratory chain failure, restoring the redox status. The results support the existence of an inducible mtNOS that is likely coded by the same gene as iNOS. The results also suggest that sepsis-induced mtNOS is responsible for the increase of mitochondrial impairment due to oxidative stress in sepsis, perhaps due to the high production of NO. Melatonin treatment prevents mitochondrial failure at the same extend as the lack of iNOS gene.

• Authors: Luis C López, Germaine Escames, Víctor Tapias, Pilar Utrilla, Josefa León, Darío Acuña-Castroviejo
• Journal: The international journal of biochemistry & cell biology (Int J Biochem Cell Biol) Vol. 38 Issue 2 Pg. 267-78 (Feb 2006) ISSN: 1357-2725 [Print] Netherlands
• PMID: 16223598 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Isoenzymes
• Nitrites
• Nitric Oxide Synthase Type II
• Glutathione
• Melatonin

Topics

• Animals
• Diaphragm (cytology, enzymology)
• Electron Transport (physiology)
• Glutathione (metabolism)
• Isoenzymes (genetics, metabolism)
• Melatonin (metabolism, pharmacology)
• Mice
• Mice, Inbred C57BL
• Mice, Knockout
• Mitochondria (drug effects, enzymology)
• Nitric Oxide Synthase Type II (genetics, metabolism)
• Nitrites (metabolism)
• Oxidation-Reduction
• Oxidative Stress
• Sepsis (metabolism)