Abstract: Objective To explore an method for diffuse axonal injury (DAI) diagnosis and injury time esti-mation, the changes of β- APP immunoreactivity and to observe the morphology of axonal in different partsof brain after experimental DAI injury. Methods The animal models of DAI was established according tothe Marmarou′s method. Immunohistochemistry and Gless staining were performed to observe the changesof β- APP expression and the morphology of axon with the time elapsed after the DAI injury. Results Inthe brain injury group, the morphologic changes of axon in brain stem were showed as twisted,broken andswellen at 0.5h , and the myelin sheaths broken could be observed, the retraction ball was found at 12h. Those morphology changes further progressed at 12h, reached to peack up to 1d, then repaired at 3d,and recovered at 10d; Meanwhile the analysis of β- APP immunoreactivity was also showed a time- depen-dent difference as fellows: β- APP expression begin at 3h, increased its immunoreactivity at 12h, reachedto maximize at 1 d, decreased after 3 d, returned to basal level at 10 d. Conclusions The results suggestthat β- APP immunohistochemistry combine with Gless staining be sensitive methods for DAI diagnosis,they could discover the time- dependent changes of the axonal morphology.The changes β- APP are quiteregular and could be used for timing DAI injury.

Key words: diffuse axonal injury, β- amyloid precursor protein, immunohistochemistry, injury time estimation