euk-189 and diacetyldichlorofluorescein

We determined the roles of reactive oxygen species (ROS) in the expression of cyclooxygenase-2 (COX-2) and the production of prostaglandin E2 (PGE2) in lipopolysaccharide (LPS)-activated microglia. LPS treatment increased intracellular ROS in rat microglia dose-dependently. Pre-treatment with superoxide dismutase (SOD)/catalase, or SOD/catalase mimetics that can scavenge intracellular ROS, significantly attenuated LPS-induced release in PGE2. Diphenylene iodonium (DPI), a non-specific NADPH oxidase inhibitor, decreased LPS-induced PGE2 production. In addition, microglia from NADPH oxidase-deficient mice produced less PGE2 than those from wild-type mice following LPS treatment. Furthermore, LPS-stimulated expression of COX-2 (determined by RT-PCR analysis of COX-2 mRNA and western blot for its protein) was significantly reduced by pre-treatment with SOD/catalase or SOD/catalase mimetics. SOD/catalase mimetics were more potent than SOD/catalase in reducing COX-2 expression and PGE2 production. As a comparison, scavenging ROS had no effect on LPS-induced nitric oxide production in microglia. These results suggest that ROS play a regulatory role in the expression of COX-2 and the subsequent production of PGE2 during the activation process of microglia. Thus, inhibiting NADPH oxidase activity and subsequent ROS generation in microglia can reduce COX-2 expression and PGE2 production. These findings suggest a potential therapeutic intervention strategy for the treatment of inflammation-mediated neurodegenerative diseases.

Topics: Animals; Animals, Newborn; Blotting, Western; Brain; Catalase; Catecholamines; Cell Count; Cells, Cultured; Cyclooxygenase 2; Dinoprostone; Dose-Response Relationship, Drug; Drug Interactions; Extracellular Space; Female; Fluoresceins; Imidazolines; Intracellular Space; Isoenzymes; Lipopolysaccharides; Mice; Mice, Inbred C57BL; Mice, Knockout; Microglia; NADPH Oxidases; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Organometallic Compounds; Pregnancy; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Inbred F344; Reactive Oxygen Species; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Salicylates; Superoxide Dismutase; Tetrazolium Salts; Thiazoles