title: Mitogen-activated protein kinases support survival of activated microglia that mediate thrombin-induced striatal injury in organotypic slice culture.
abstract: Intracerebral hemorrhage-associated tissue damage is triggered by blood-derived serine proteases such as thrombin. In addition, our previous studies have suggested that mitogen-activated protein (MAP) kinases contribute to intracerebral hemorrhage- and thrombin-induced striatal tissue damage in vivo. Here we addressed the mechanisms of MAP kinase involvement in thrombin cytotoxicity in rat corticostriatal slice culture, focusing on striatal tissue damage. Thrombin induced apoptotic nuclear condensation and fragmentation in striatal cells, which was suppressed by DEVD-CHO, a caspase-3 inhibitor. DEVD-CHO also prevented shrinkage of the striatal tissue induced by thrombin. Phagocytotic activity may be involved in tissue deterioration, because a phagocytosis inhibitor (cytochalasin D) and an inhibitor of phagocytosis of apoptotic cells (O-phospho-L-serine) suppressed shrinkage of the striatal tissue. OX42 immunostaining revealed that apoptosis-like microglial cell death was induced only when thrombin treatment was combined with application of inhibitors of MAP kinase/extracellular signal-regulated kinase kinase (PD98059), p38 MAP kinase (SB203580), or c-Jun N-terminal kinase (SP600125). Thrombin-induced increase in the number of microglia was also prevented by these inhibitors of MAP kinase pathways. We also found that thrombin-induced production of tumor necrosis factor (TNF)-alpha was inhibited by PD98059, SB203580, and SP600125. Finally, thrombin-induced neuronal apoptosis and shrinkage of the striatal tissue were significantly inhibited by anti-TNF-alpha neutralizing antibody. These results suggest that MAP kinases contribute to thrombin-induced striatal damage by supporting survival of activated microglia, which induce neuron death by producing TNF-alpha and cause tissue shrinkage by phagocytosing apoptotic cells.
authors.affiliation: Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Ohnishi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Katsuki
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Izumi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Kume
authors.forename: Yuki
authors.initials: Y
authors.lastname: Takada-Takatori
authors.forename: Akinori
authors.initials: A
authors.lastname: Akaike
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001930:Brain Injuries / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology*; D002470:Cell Survival / Q000502:physiology; D002540:Cerebral Cortex; D003342:Corpus Striatum / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D017628:Microglia / Q000187:drug effects / Q000473:pathology / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000473:pathology / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013917:Thrombin / Q000378:metabolism*; D046509:Tissue Culture Techniques; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D014409:Tumor Necrosis Factor-alpha; D020928:Mitogen-Activated Protein Kinases; D013917:Thrombin