[Expression of beta-amyloid precursor protein in diffuse axonal injury of rats]

To explore an method for diffuse axonal injury (DAI) diagnosis and injury time estimation, the changes of beta-APP immunoreactivity and to observe the morphology of axonal in different parts of brain after experimental DAI injury.

The animal models of DAI was established according to the Marmarou's method. Immunohistochemistry and Gless staining were performed to observe the changes of beta-APP expression and the morphology of axon with the time elapsed after the DAI injury.

In the brain injury group, the morphologic changes of axon in brain stem were showed as twisted, broken and swellen at 0.5 h, and the myelin sheaths broken could be observed, the retraction ball was found at 12 h. Those morphology changes further progressed at 12h, reached to peack up to 1 d, then repaired at 3 d, and recovered at 10 d; Meanwhile the analysis of beta-APP immunoreactivity was also showed a time-dependent difference as fellows: beta-APP expression begin at 3h, increased its immunoreactivity at 12h, reached to maximize at 1 d, decreased after 3 d, returned to basal level at 10 d.

The results suggest that beta-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 beta-APP are quite regular and could be used for timing DAI injury.