Contribution of inducible and neuronal nitric oxide synthases to mitochondrial damage and melatonin rescue in LPS-treated mice

J Physiol Biochem. 2017 May;73(2):235-244. doi: 10.1007/s13105-017-0548-2. Epub 2017 Jan 21.

Abstract

NOS isoform activation is related to liver failure during sepsis, but the mechanisms driving mitochondrial impairment remain unclear. We induced sepsis by LPS administration to inducible nitric oxide synthase (iNOS-/-) and neuronal nitric oxide synthase (nNOS-/-) mice and their respective wild-type controls to examine the contribution of iNOS to mitochondrial failure in the absence of nNOS. To achieve this goal, the determination of messenger RNA (mRNA) expression and protein content of iNOS in cytosol and mitochondria, the mitochondrial respiratory complex content, and the levels of nitrosative and oxidative stress (by measuring 3-nitrotyrosine residues and carbonyl groups, respectively) were examined in the liver of control and septic mice. We detected strongly elevated iNOS mRNA expression and protein levels in liver cytosol and mitochondria of septic mice, which were related to enhanced oxidative and nitrosative stress, and with fewer changes in respiratory complexes. The absence of the iNOS, but not nNOS, gene absolutely prevented mitochondrial impairment during sepsis. Moreover, the nNOS gene did not modify the expression and the effects of iNOS here shown. Melatonin administration counteracted iNOS activation and mitochondrial damage and enhanced the expression of the respiratory complexes above the control values. These effects were unrelated to the presence or absence of nNOS. iNOS is a main target to prevent liver mitochondrial impairment during sepsis, and melatonin represents an efficient antagonist of these iNOS-dependent effects whereas it may boost mitochondrial respiration to enhance liver survival.

Keywords: Free radicals; LPS; Liver; Melatonin; Mitochondria; Nitric oxide synthase.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Antioxidants / administration & dosage
  • Antioxidants / therapeutic use*
  • Biomarkers / blood
  • Disease Models, Animal*
  • Gene Expression Regulation, Enzymologic / drug effects
  • Hepatic Insufficiency / etiology
  • Hepatic Insufficiency / prevention & control*
  • Injections, Intraperitoneal
  • Lipopolysaccharides / toxicity
  • Liver / drug effects*
  • Liver / immunology
  • Liver / metabolism
  • Melatonin / administration & dosage
  • Melatonin / therapeutic use*
  • Mice, 129 Strain
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mitochondria, Liver / drug effects
  • Mitochondria, Liver / immunology
  • Mitochondria, Liver / metabolism
  • Nitric Oxide Synthase Type I / genetics
  • Nitric Oxide Synthase Type I / metabolism
  • Nitric Oxide Synthase Type II / genetics
  • Nitric Oxide Synthase Type II / metabolism*
  • Oxidative Stress / drug effects
  • Protein Carbonylation / drug effects
  • RNA, Messenger / metabolism
  • Sepsis / drug therapy*
  • Sepsis / immunology
  • Sepsis / metabolism
  • Sepsis / physiopathology

Substances

  • Antioxidants
  • Biomarkers
  • Lipopolysaccharides
  • RNA, Messenger
  • Nitric Oxide Synthase Type I
  • Nitric Oxide Synthase Type II
  • Nos1 protein, mouse
  • Nos2 protein, mouse
  • Melatonin