[Preliminary results of the study of neuronal death and the expression of bcl-2 protein in Alzheimer's disease]

Abstract

Alzheimer's disease (AD) is a degenerative central nervous system disorder where beside the histopathologic features of senile plaques and neurofibrillary tangles there is an important neuronal loss. It has been suggested that this neuronal death occurs via an apoptotic mechanism. Recognition of apoptotic cells is possible by an in situ end-labeling technique which identify the 3'-OH termini of DNA strands breaks through the incorporation of labeled nucleotides with the enzyme terminal-deoxinucleotidyl transferase (Tdt). We have applied this technique and high densities of apoptotic cells were found in 5 AD brains compared to 5 age-matched normal samples. We studied by immunohistochemical analyses the expression of the antiapoptotic protein bcl-2. We have not found neuronal bcl-2 immunoreactivity and we found an increased expression of bcl-2 by astrocytes compared to controls, this fact may aid glial survival or may have a deleterious effect on neuronal viability.