Multiple inhibitory pathways for lipopolysaccharide- and pro-inflammatory cytokine-induced nitric oxide production in cultured astrocytes.
We previously showed that lipopolysaccharide (LPS) and pro-inflammatory cytokines utilized different mechanisms for the production of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) in cultured rat astrocytes. To further characterize these regulatory pathways, we tested the effects of inhibitory factors (anti-inflammatory cytokines, cellular cAMP, and glucocorticoid) on aspects of iNOS expression (from transcription to enzyme activity) during LPS- and cytokine-induced astrocyte NO production. Anti-inflammatory cytokines (transforming growth factor-beta and interleukin-4) suppressed both LPS- and cytokine-induced NO production by reducing iNOS protein expression without affecting mRNA levels. Increased cellular cAMP levels, induced by noradrenaline or forskolin, suppressed LPS-induced, but not cytokine-induced, NO production without affecting iNOS protein expression. The glucocorticoid analog, dexamethasone, suppressed LPS-induced, but not cytokine-induced, NO production by reducing iNOS promoter activity. These different mechanisms would allow the fine control of NO concentration in the brain, as well as accounting for the multiple roles of NO in brain physiology and pathology. Moreover, these mechanisms provide useful therapeutic targets for the treatment of neurodegenerative diseases.
Kozuka
N
N
Laboratory of Cellular Neurobiology, School of Life Science, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, 192-0392 Tokyo, Japan.
Kudo
Y
Y
Morita
M
M
D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D001921:Brain / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D004660:Encephalitis / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology; D018836:Inflammation Mediators / Q000494:pharmacology*; D015847:Interleukin-4 / Q000378:metabolism / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000494:pharmacology
D016207:Cytokines; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D015847:Interleukin-4; D009569:Nitric Oxide; D003907:Dexamethasone; D000242:Cyclic AMP; D052247:Nitric Oxide Synthase Type II