Objective  To investigate the expression of erythropoietin (EPO)and its receptor (EPOR) in adult rat brain after acute traumatic brain injury.    Methods  One hundred and thirty Wistar rats were randomly divided into three groups: normal control group (n=10)

sham operation group (n=60) and brain injury group (n=60). The sham operation group and brain injury group were further randomly divided into 6 subgroups respectively according to different time points for sacrifice of the animals (5 h

12 h

24 h

3 d

5 d

7 d). The expressions of EPO and EPOR at different time points were detected by reverse transcription polymerase chain reaction (RT-PCR) and immunofluorescence staining.   Results  EPO and its receptor mRNA expressed in normal control group and sham operation group at each time point were just a small amount. RT-PCR and immunofluorescence stain revealed EPO mRNA and protein expressions sharply increased at 12 h

peaked at 3 d

gradually declined to 5 d

returned to normal level at 7 d. EPOR mRNA and protein expressions in brain injury group began to increase at 12 h after injury

peaked at 24 h

sustained to 7 d.   Conclusion  EPOR expression was significantly upregulated at least for 6 days after acute traumatic brain injury

while EPO mRNA and its protein were only shortly elevated. The protective mechanism of EPO on central nerve is possibly related to the markedly increased expression of erythropoietin receptor after traumatic brain injury.