title: [Effect of hyperoxia exposure on the function of N9 microglia in vitro].
abstract: OBJECTIVE
  To observe the effect of normobaric hyperoxia exposure on the functions of N9 microglia and explore the underlying mechanism of hyperoxia-induced immature brain injury.
  
  
  METHODS
  N9 microglial cells were exposed to 900 ml/L O(2) for 2, 6, 12, 24 or 48 h, and the cell apoptotic rate was assessed using flow cytometry. The intracellular oxidative stress was measured using a fluorescent DCFH-DA probe, and the expression of Toll-like receptor 4 (TLR4) mRNA was detected using RT-PCR. Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) concentrations in the supernatant of the cell cultures were tested with ELISA following the exposures. TLR4 protein expression was observed using immunofluorescence staining.
  
  
  RESULTS
  Significant cell apoptosis was detected after oxygen exposures for 12-24 h. Accumulation of reactive oxygen species (ROS) were detected after a 2-h exposure. After prolonged hyperoxia exposure, TLR4 expression and IL-1β and TNF-α levels significantly increased in the cells.
  
  
  CONCLUSIONS
  Hyperoxia exposure activates TLR4 signaling pathway in N9 microglial cells in vitro, leading to massive production of ROS, IL-1β, and TNF-α and thus triggering cell apoptosis.
authors.affiliation: Department of Forensic Medicine, Chongqing Medical University, Chongqing, China. jiangpu_e@163.com
authors.forename: Pu
authors.initials: P
authors.lastname: Jiang
authors.forename: Ying
authors.initials: Y
authors.lastname: Xu
authors.forename: Liangan
authors.initials: L
authors.lastname: Hu
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Shixiong
authors.initials: S
authors.lastname: Deng
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015687:Cell Hypoxia; D002478:Cells, Cultured; D053583:Interleukin-1beta / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D017628:Microglia / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D010100:Oxygen / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism
chemical_list: D053583:Interleukin-1beta; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D010100:Oxygen