Expression of inducible nitric oxide synthase mRNA in Brown Norway rats exposed to ozone: effect of dexamethasone.
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.
Haddad
E B
EB
Department of Thoracic Medicine, National Heart and Lung Institute, London, UK.
Liu
S F
SF
Salmon
M
M
Robichaud
A
A
Barnes
P J
PJ
Chung
K F
KF
D000280:Administration, Inhalation; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001483:Base Sequence; D015152:Blotting, Northern; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002452:Cell Count; D017931:DNA Primers / Q000737:chemistry; D015342:DNA Probes; D003907:Dexamethasone / Q000494:pharmacology*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D007274:Injections, Intraperitoneal; D008168:Lung / Q000187:drug effects / Q000201:enzymology*; D008969:Molecular Sequence Data; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000235:genetics; D010083:Oxidants, Photochemical / Q000008:administration & dosage / Q000633:toxicity*; D010126:Ozone / Q000008:administration & dosage / Q000633:toxicity*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011914:Rats, Inbred BN
D000893:Anti-Inflammatory Agents; D017931:DNA Primers; D015342:DNA Probes; D010083:Oxidants, Photochemical; D012333:RNA, Messenger; D010126:Ozone; D003907:Dexamethasone; D019001:Nitric Oxide Synthase