Abstract: Objective To observe the change of c－ fos protein(Fos) and nerve growth factor receptor(NGFR) staining in the brain of rat after experimental brain contusion. Methods Immunohistochemistry of c fos and NGFR were applied to investigate the brain contusion. Results (1)The expression of Fos protein could be observed at 0.5h after injury and then increased with the prolonging of time.By 3h after injury,the positive staining cells could be detected massively not only in and round the wound site but also in other areas of the whole ipsilateral cortex.The stains decreased 6－ 12h later and could hardly be detected 1d after the brain contusion.The control－ experiment is negotive. (2)NGFR positive staining cells could be found round the wound area 1d postlesion. At 3d following injury,a peak of massive positively stained cells appeared both in number and in intensity, showing significant differences compaired with that of 1d after damage (P< 0.01). 5d later the positive express declined slowly.The express in the control－ rat is negotive. Conclusion There is a rule that the exprssion of Fos and NGFR positive staining changes with time going after brain contusion,which will be of great value in estimation of brain injury time. Detection of Fos can be used for time deduction in earlier period after injury,while NGFR in later period. They are also very important for distinguishing between antemortem or postmortem injury.

Key words: brain contusion, immunohistochemistry, injury time, Fos, NGFR