title: Midazolam suppresses interleukin-1β-induced interleukin-6 release from rat glial cells.
abstract: BACKGROUND
  Peripheral-type benzodiazepine receptor (PBR) expression levels are low in normal human brain, but their levels increase in inflammation, brain injury, neurodegenerative states and gliomas. It has been reported that PBR functions as an immunomodulator. The mechanisms of action of midazolam, a benzodiazepine, in the immune system in the CNS remain to be fully elucidated. We previously reported that interleukin (IL)-1β stimulates IL-6 synthesis from rat C6 glioma cells and that IL-1β induces phosphorylation of inhibitory kappa B (IκB), p38 mitogen-activated protein (MAP) kinase, stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase 1/2, and signal transducer and activator of transcription (STAT)3. It has been shown that p38 MAP kinase is involved in IL-1β-induced IL-6 release from these cells. In the present study, we investigated the effect of midazolam on IL-1β-induced IL-6 release from C6 cells, and the mechanisms of this effect.
  
  
  METHODS
  Cultured C6 cells were stimulated by IL-1β. IL-6 release from C6 cells was measured using an enzyme-linked immunosorbent assay, and phosphorylation of IκB, the MAP kinase superfamily, and STAT3 was analyzed by Western blotting.
  
  
  RESULTS
  Midazolam, but not propofol, inhibited IL-1β-stimulated IL-6 release from C6 cells. The IL-1β-stimulated levels of IL-6 were suppressed by wedelolactone (an inhibitor of IκB kinase), SP600125 (an inhibitor of SAPK/JNK), and JAK inhibitor I (an inhibitor of JAK 1, 2 and 3). However, IL-6 levels were not affected by PD98059 (an inhibitor of MEK1/2). Midazolam markedly suppressed IL-1β-stimulated STAT3 phosphorylation without affecting the phosphorylation of p38 MAP kinase, SAPK/JNK or IκB.
  
  
  CONCLUSIONS
  These results strongly suggest that midazolam inhibits IL-1β-induced IL-6 release in rat C6 glioma cells via suppression of STAT3 activation. Midazolam may affect immune system function in the CNS.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan. kumiko-t@m2.gyao.ne.jp
authors.forename: Kumiko
authors.initials: K
authors.lastname: Tanabe
authors.forename: Osamu
authors.initials: O
authors.lastname: Kozawa
authors.forename: Hiroki
authors.initials: H
authors.lastname: Iida
mesh_terms: D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D002478:Cells, Cultured; D003374:Coumarins / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D018757:GABA Modulators / Q000494:pharmacology*; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D053583:Interleukin-1beta / Q000494:pharmacology*; D015850:Interleukin-6 / Q000378:metabolism*; D008874:Midazolam / Q000494:pharmacology*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009457:Neuroglia / Q000187:drug effects* / Q000378:metabolism*; D015742:Propofol / Q000494:pharmacology; D051381:Rats; D050796:STAT3 Transcription Factor / Q000378:metabolism
chemical_list: D000873:Anthracenes; D003374:Coumarins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D018757:GABA Modulators; D006993:Hypnotics and Sedatives; D053583:Interleukin-1beta; D015850:Interleukin-6; D050796:STAT3 Transcription Factor; C051122:wedelolactone; C432165:pyrazolanthrone; D020928:Mitogen-Activated Protein Kinases; D008874:Midazolam; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D015742:Propofol