Parvalbumin Neurons in the Hippocampus in Senile Dementia of the Alzheimer Type, Parkinson's Disease and Multi-Infarct Dementia (Part 2 of 2)

Abstract

The immunogold-silver-staining method (IGSS) was used for the detection of hippocampal neurons containing the cytoplasmic calcium-binding protein parvalbumin in senile dementia of the Alzheimer type (SDAT), Parkinson's disease and multi-infarct dementia (MID). Computer-based image analysis of cell numbers in the hippocampus proper and the entorhinal cortex, measurement of total dendritic length of selected neurons and quantitative microdensitometry of immunoreacted sections was performed. In severe SDAT cases a loss of parvalbumin-immunoreactive (parv-i) neurons and a reduction of dendritic fields was detected especially in CA1 and the subiculum. In the entorhinal cortex the general atrophy exceeded the decrease of parvalbumin immunoreactivity. Mild SDAT cases showed only minor alterations of parv-i neurons and in cases of parkinsonism without cognitive disorders or in those with depression parv-i neurons were not affected. However, in cases of parkinsonism with dementia and in MID a severe cell loss and a drastic reduction of dendritic arborization in the hippocampus proper was detected, which was accompanied by additional morphological alterations due to ischemic damage. We conclude that parv-i neuronal networks in the hippocampus are damaged in some patients with dementing disorders in SDAT, Parkinson's disease and MID consecutive to Alzheimer or ischemia related pathology.