Effect of hyperoxia exposure on the function of N9 microglia in vitro / 南方医科大学学报

ABSTRACT

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>