Modified Bielschowsky stain and immunohistochemical studies on striatal plaques in Alzheimer's disease

The nature of senile plaques (SP) in the striatum in 14 cases of Alzheimer's disease (AD) was investigated with the modified Bielschowsky stain and immunohistochemistry using antibodies to a beta amyloid synthetic peptide, ubiquitin, tau protein, and paired helical filaments (PHF). Striatal SP, composed of beta amyloid deposits with or without neuritic elements, were demonstrated in all AD cases examined. Compact and perivascular amyloid deposits were concentrated in the ventral striatum, including the nucleus accumbens. Many diffuse amyloid deposits in the ventral striatum contained ubiquitin-positive granular elements, presumably representing dystrophic neurites, whereas most of those in the dorsal striatum did not have such elements. On the other hand, most compact amyloid deposits in both ventral and dorsal striatum had ubiquitin immunoreactivity. Dystrophic neurites with tau or PHF immunoreactivity were detected particularly around compact amyloid deposits. Our results indicate that the ventral striatum, which is closely affiliated with the limbic system, is frequently affected by amyloid deposits with dystrophic neurites, and suggest that the ventral striatum is particularly vulnerable to AD. Furthermore, our results suggest that amyloid deposits, especially compact deposits, may induce dystrophic neurites.