Objective    To explore the mechanism of the microglia inflammatory response through observing the changes of interleukin-1 receptor associated kinase-4(IRAK-4) expression in murine N9 microglia cells under hypoxia.     Methods    N9 cells were exposed to 3%O

2

5%CO

2

92%N

2

for 1

3

6

12 and 24 h respectively. The IRAK-4 protein level was detected by Western blotting and the celluar change was observed by laser scanning confocal microscope(LSCM).  The TNF-α level was measured by EL

ISA.     Results    After hypoxia

the expression of IRAK-4  protein was increased in a time-dependent manner.  The elevation began at 1 h after hypoxia

increased significantly at 3 h(P0.01)

peaked at 6 h and remained in higher level at 12 h(P0.01). then decreased at 24 h (P0.05).  The fluorescence intensity of IRAK-4 also increased with the extension of anoxic time. The TNF-α level change were similar. There were significant positive correlations between the expression of IRAK-4 and TNF-α(P0.05).     Conclusion    Hypoxia could increase IRAK-4 expression in murine microglia cells. It suggests that TLR/IL-IR signaling may exist in central nervous system and regulate the subsequent inflammation response.