β-Amyloid precursor protein (βAPP) as a marker for axonal injury after head injury

Abstract

It has been demonstrated recently that β-amyloid protein (βAP), generally associated with the plaques of Alzheimer's disease, can also be found in the brains of survivors of head injury. In this study the distribution of the βAP precursor protein (βAPP) was examined immunohistochemically to determine if it is colocalized with βAP in such cases. βAPP immunoreactivity was observed in neuronal perikarya in the neocortex and in dystrophic neurites surrounding βAP immunoreactive plaques i.e. in a distribution similar to that seen in Alzheimer's disease. In addition, βAPP immunoreactivity was noted within white matter tracts where it marked damaged axons. However, no colocalisation of βAPP with βAP was observed in any white matter region. These results indicate that processing of βAPP to produce βAP occurs in the synaptic terminal field of axons and illustrate the utility of βAPP immunoreactivity as a general marker for axonal injury.