Expression of amyloid precursor protein after rat traumatic brain injury.
OBJECTIVE
Previous reports have demonstrated that some focal brain injuries increase amyloid precursor protein (APP) immunoreactivity in the region surrounding the injury in the cerebral cortex. However, the chronologic changes in APP expression have not been evaluated after traumatic brain injury (TBI).


METHODS
In this study, we immunohistochemically and biologically investigated chronologic changes in cellular sources and levels of APP production after rat TBI.


RESULTS
In the present report, we show that traumatic brain injury increased the expression of APP in the neuronal perikarya and in damaged dystrophic neurites from 1 to 90 days after injury. Moreover, 7 days after injury, some macrophages/microglia also were co-localized with APP, which was overproduced by the neuronal perikarya and APP-positive dystrophic neurites after injury and then APP were phagocytosed by macrophages/microglia during this phase. However, astroglia did not express APP immunopositivity after brain injury.


CONCLUSIONS
These results suggested that long-term overexpression of APP was confirmed by immunohistochemical and biologic technique after TBI. This may be related to the induction of Alzheimer type dementia and it is a very important risk factor for this disease.
Itoh
Tatsuki
T
Department of Pathology, Kinki University School of Medicine, Okasayyama City, Osaka, Japan. tatsuki@med.kindai.ac.jp
Satou
Takao
T
Nishida
Shozo
S
Tsubaki
Masahiro
M
Hashimoto
Shigeo
S
Ito
Hiroyuki
H
D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D001930:Brain Injuries / Q000378:metabolism* / Q000473:pathology*; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D007150:Immunohistochemistry; D008297:Male; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction
D016564:Amyloid beta-Protein Precursor; D012333:RNA, Messenger