Upregulation of iNOS by COX-2 in muscularis resident macrophage of rat intestine stimulated with LPS.
We investigated the effect of lipopolysaccharide (LPS) on the induction of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in muscularis resident macrophages of rat intestine in situ. When the tissue was incubated with LPS for 4 h, mRNA levels of iNOS and COX-2 were increased. The majority of iNOS and COX-2 proteins appeared to be localized to the dense network of muscularis resident macrophages immunoreactive to ED2. LPS treatment also increased the production of nitric oxide (NO), PGE(2), and PGI(2). The increased expression of iNOS mRNA by LPS was suppressed by indomethacin but not by N(G)-monomethyl-L-arginine (L-NMMA). The increased expression of COX-2 mRNA by LPS was affected neither by indomethacin nor by L-NMMA. Muscle contractility stimulated by 3 microM carbachol was significantly inhibited in the LPS-treated muscle, which was restored by treatment of the tissue with L-NMMA, aminoguanidine, indomethacin, or NS-398. Together, these findings show that LPS increases iNOS expression and stimulates NO production in muscularis resident macrophages to inhibit smooth muscle contraction. LPS-induced iNOS gene expression may be mediated by autocrine regulation of PGs through the induction of COX-2 gene expression.
Hori
M
M
Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan. ahori@mail.ecc.u-tokyo.ac.jp
Kita
M
M
Torihashi
S
S
Miyamoto
S
S
Won
K J
KJ
Sato
K
K
Ozaki
H
H
Karaki
H
H
D000818:Animals; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000378:metabolism; D004790:Enzyme Induction; D011464:Epoprostenol / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D007082:Ileum / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics*; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000166:cytology / Q000201:enzymology*; D008297:Male; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000235:genetics*; D052247:Nitric Oxide Synthase Type II; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000187:drug effects; D019323:omega-N-Methylarginine / Q000494:pharmacology
D007527:Isoenzymes; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D011464:Epoprostenol; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone; D007213:Indomethacin