title: Thrombin induces NO release from cultured rat microglia via protein kinase C, mitogen-activated protein kinase, and NF-kappa B.
abstract: Microglia, brain resident macrophages, become activated in brains injured due to trauma, ischemia, or neurodegenerative diseases. In this study, we found that thrombin treatment of microglia induced NO release/inducible nitric-oxide synthase expression, a prominent marker of activation. The effect of thrombin on NO release increased dose-dependently within the range of 5-20 units/ml. In immunoblot analyses, inducible nitric-oxide synthase expression was detected within 9 h after thrombin treatment. This effect of thrombin was significantly reduced by protein kinase C inhibitors, such as Go6976, bisindolylmaleimide, and Ro31-8220. Within 15 min, thrombin activated three subtypes of mitogen-activated protein kinases: extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase/stress-activated protein kinase. Inhibition of the extracellular signal-regulated kinase pathway and p38 reduced the NO release of thrombin-treated microglia. Thrombin also activated nuclear factor kappaB (NF-kappaB) within 5 min, and N-acetyl cysteine, an inhibitor of NF-kappaB, reduced NO release. However, thrombin receptor agonist peptide (an agonist of protease activated receptor-1 (PAR-1)), could not mimic the effect of thrombin, and cathepsin G, a PAR-1 inhibitor, did not reduce the effect of thrombin. These results suggest that thrombin can activate microglia via protein kinase C, mitogen-activated protein kinases, and NF-kappaB but that this occurs independently of PAR-1.
authors.affiliation: Department of Pharmacology, Ajou University School of Medicine, Suwon, 442-721, Korea.
authors.forename: J
authors.initials: J
authors.lastname: Ryu
authors.forename: H
authors.initials: H
authors.lastname: Pyo
authors.forename: I
authors.initials: I
authors.lastname: Jou
authors.forename: E
authors.initials: E
authors.lastname: Joe
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D002227:Carbazoles / Q000494:pharmacology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D004790:Enzyme Induction; D005419:Flavonoids / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D017628:Microglia / Q000166:cytology / Q000187:drug effects*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011506:Proteins / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin / Q000819:agonists / Q000378:metabolism; D015398:Signal Transduction; D013917:Thrombin / Q000494:pharmacology*
chemical_list: D002227:Carbazoles; D005419:Flavonoids; D007093:Imidazoles; D007211:Indoles; D008301:Maleimides; D016328:NF-kappa B; D011506:Proteins; D011725:Pyridines; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin; C081021:Go 6976; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D013917:Thrombin; C088060:bisindolylmaleimide; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; C064758:Ro 31-8220; D000111:Acetylcysteine