Induction of cyclooxygenase and nitric oxide synthase in endotoxin-activated J774 macrophages is differentially regulated by indomethacin: enhanced cyclooxygenase-2 protein expression but reduction of inducible nitric oxide synthase.
The involvement of prostaglandins in feedback modulation of the lipopolysaccharide-inducible isoforms of cyclooxygenase and nitric oxide was studied. This was done by testing the effects of arachidonic acid and indomethacin in the murine macrophage cell line J774. When added before lipopolysaccharide, arachidonic acid (10(-6)-10(-4) M) dose-dependently reduced inducible nitric oxide synthase and cyclooxygenase-2 activity as well as reducing the expression of both enzyme proteins. Indomethacin (10(-7)-10(-4) M) suppressed prostaglandin E2 release into the medium and reduced cyclooxygenase-2 activity irreversibly, as expected, but the amount of cyclooxygenase-2 protein was increased (because indomethacin removes the inhibitory effect of prostaglandins on cyclooxygenase-2 expression). However, the same doses of indomethacin also inhibited the release of nitric oxide into the medium. This was accompanied by a reduction in the amount of inducible nitric oxide synthase protein. The drug was not cytotoxic. Thus these results show that pharmacological treatments can have opposing actions on inducible nitric oxide synthase and cyclooxygenase-2 induction, with indomethacin showing an additional unexpected action in macrophages which may diminish their cytotoxic potential.
Pang
L
L
Pharmacology Group, King's College London, UK.
Hoult
J R
JR
D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D015232:Dinoprostone / Q000096:biosynthesis; D004790:Enzyme Induction / Q000187:drug effects; D007213:Indomethacin / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology*; D051379:Mice; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D009573:Nitrites / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis*
D016861:Cyclooxygenase Inhibitors; D008070:Lipopolysaccharides; D009573:Nitrites; D016718:Arachidonic Acid; D019001:Nitric Oxide Synthase; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone; D007213:Indomethacin