Abstract
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.
MeSH terms
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Animals
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Animals, Newborn
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Blotting, Western / methods
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Brain / cytology
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Catalase / pharmacology
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Catecholamines / pharmacology
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Cell Count
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Cells, Cultured
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Cyclooxygenase 2
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Dinoprostone / metabolism*
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Dose-Response Relationship, Drug
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Drug Interactions
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Extracellular Space / drug effects
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Extracellular Space / metabolism
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Female
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Fluoresceins / pharmacology
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Imidazolines*
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Intracellular Space / drug effects
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Intracellular Space / metabolism
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Isoenzymes / genetics
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Isoenzymes / metabolism
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Lipopolysaccharides / pharmacology*
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Mice
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Mice, Inbred C57BL
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Mice, Knockout
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Microglia / drug effects*
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Microglia / metabolism
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NADPH Oxidases / genetics
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Nitric Oxide / metabolism
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Nitric Oxide Synthase / metabolism
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Nitric Oxide Synthase Type II
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Organometallic Compounds / pharmacology
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Pregnancy
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Prostaglandin-Endoperoxide Synthases / genetics
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Prostaglandin-Endoperoxide Synthases / metabolism
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RNA, Messenger / biosynthesis
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Rats
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Rats, Inbred F344
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Reactive Oxygen Species / metabolism*
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Reverse Transcriptase Polymerase Chain Reaction / methods
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Salicylates / pharmacology
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Superoxide Dismutase / pharmacology
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Tetrazolium Salts / pharmacology
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Thiazoles / pharmacology
Substances
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Catecholamines
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EUK-134
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EUK-189
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Fluoresceins
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Imidazolines
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Isoenzymes
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Lipopolysaccharides
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Organometallic Compounds
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RNA, Messenger
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Reactive Oxygen Species
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Salicylates
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Tetrazolium Salts
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Thiazoles
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diacetyldichlorofluorescein
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Nitric Oxide
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(3,4-dihydroxyphenylamino)-2-imidazoline
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Catalase
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Nitric Oxide Synthase
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Nitric Oxide Synthase Type II
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Nos2 protein, mouse
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Nos2 protein, rat
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Cyclooxygenase 2
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Prostaglandin-Endoperoxide Synthases
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Superoxide Dismutase
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NADPH Oxidases
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thiazolyl blue
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Dinoprostone