Objective    To observe the expression and phosphorylation of N-methyl-D-aspartate (NMDA) receptor NR1 subunit in rat cortex and hippocampus under high altitude hypoxia.     Methods    The adult SD rats were exposed to hypobaric hypoxia imitating 5 500-meter high altitude for 8 h daily for 3

7

14

21 d. Immunohistochemical staining

Western blotting and co-immunoprecipitation were used to detect the expression and phosphorylation of NR1 in rat cortex and hippocampus.     Results    Both immunohistochemistry and Western blotting showed NR1 expression in rat cortex and hippocampus was increased under hypoxia in a time-dependent manner. The tyrosine phosphorylation of hypoxia groups was increased

and reached the peak on day 14 after hypoxia

then decreased

still higher than that of control groups till day 21 (P0.01).     Conclusion    The increase of tyrosine phosphorylation of NR1 subunit in rat cortex and hippocampus under hypoxia may be a key influencing factor for NMDA receptor function.