Immunoreactivity for Bcl-2 protein within neurons in the Alzheimer's disease brain increases with disease severity.
Bcl-2 protein has been suggested to be one of the proteins preventing apoptosis in a variety of cell types. Recently, apoptosis has been suggested to have an important role in the pathogenesis of Alzheimer's disease (AD). We have utilized Bcl-2 immunohistochemical methods to examine Bcl-2 in the hippocampus and entorhinal cortex of AD patients ranging in clinical and neuropathological severity from mild to severe and compared these results to those obtained from age-matched controls. Immunoreactivity for Bcl-2 was predominantly found within neurons. Bcl-2 immunostaining within AD tissue was increased relative to controls in most neurons of the entorhinal cortex, subiculum, CA1, CA2, CA3, hilus and dentate gyrus. Relative Bcl-2 staining increased in parallel with increasing disease severity. However, neurons exhibiting immunoreactivity for markers of neurofibrillary tangle formation (AT8 and PHF-1) showed reduced Bcl-2 staining, suggesting that Bcl-2 may be down regulated in these degenerating neurons. Bcl-2 immunoreactivity within astrocytes and the vasculature was also increased in AD. These results suggest that Bcl-2 protein may have a role in compensation responses to AD pathology, perhaps affording to the remaining neurons a margin of protection from apoptosis.
Satou
T
T
Institute for Brain Aging and Dementia, University of California, Irvine 92717-4550, USA.
Cummings
B J
BJ
Cotman
C W
CW
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000378:metabolism* / Q000473:pathology; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D018450:Disease Progression; D006801:Humans; D007124:Immunoenzyme Techniques; D009474:Neurons / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2; D012016:Reference Values
D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2