Expression of inducible nitric oxide synthase mRNA in Brown Norway rats exposed to ozone: effect of dexamethasone

Eur J Pharmacol. 1995 Oct 6;293(3):287-90. doi: 10.1016/0926-6917(95)00032-1.


We studied the effects of ozone exposure and dexamethasone on inducible nitric synthase (iNOS) gene expression in Brown Norway rats in vivo. Using a murine iNOS cDNA probe, we detected a 4.4 kb iNOS mRNA by Northern analysis in rat lung. The iNOS signal was weak in control lungs, but increased in lungs exposed to ozone (3 ppm, 6 h). Ozone-induced iNOS mRNA expression was time-dependent, with maximal expression at 2 h, declining by 8 h and increasing again at 24 h postexposure. Dexamethasone significantly reduced the iNOS mRNA expression in the lungs of both controls and ozone-exposed rats. These results demonstrate that ozone inhalation induces iNOS expression in vivo, thus providing evidence at the molecular level for the possible involvement of nitric oxide generation in ozone-induced pulmonary inflammation or lung damage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Inhalation
  • Animals
  • Anti-Inflammatory Agents / pharmacology*
  • Base Sequence
  • Blotting, Northern
  • Bronchoalveolar Lavage Fluid / cytology
  • Cell Count
  • DNA Primers / chemistry
  • DNA Probes
  • Dexamethasone / pharmacology*
  • Female
  • Gene Expression Regulation, Enzymologic / drug effects
  • Injections, Intraperitoneal
  • Lung / drug effects
  • Lung / enzymology*
  • Molecular Sequence Data
  • Nitric Oxide Synthase / biosynthesis*
  • Nitric Oxide Synthase / genetics
  • Oxidants, Photochemical / administration & dosage
  • Oxidants, Photochemical / toxicity*
  • Ozone / administration & dosage
  • Ozone / toxicity*
  • RNA, Messenger / biosynthesis
  • Rats
  • Rats, Inbred BN


  • Anti-Inflammatory Agents
  • DNA Primers
  • DNA Probes
  • Oxidants, Photochemical
  • RNA, Messenger
  • Ozone
  • Dexamethasone
  • Nitric Oxide Synthase