Hippocampal pathology in diffuse Lewy body disease using ubiquitin immunohistochemistry

Various ubiquitin-positive structures in the hippocampus in diffuse Lewy body disease (n=12) and non-demented aged subjects (n=3) were investigated immunohistochemically. These structures were composed of ubiquitin-positive granular structures (UPG), ubiquitin-positive neuritic structures (UPN), spheroidal structures, neuritic plaques, neurofibrillary tangles (NFT), Lewy bodies (LB) and ubiquitin-positive neurons. UPG, UPN, spheroidal structures and neuritic plaques were distributed with special reference to the hippocampal pathway assumed in this study. This pathway was thought to run along the stratum oriens, mostly perforating the stratum pyramidale at many sites of the subiculum and CA1-3, and to end partly in the CA2-3 and the subiculum of the uncus (UPG or UPN). After perforating the stratum pyramidale and giving off terminal branches (ubiquitin-positive neurons or neuritic plaques with degenerative neurites), it was thought to run along the stratum radiatum and continue along the stratum moleculare of the dentate gyrus, forming synapses with the apical dendrites from the stratum pyramidale and the stratum granulosum (spheroidal structures or neuritic plaques). These findings suggest that many of the ubiquitin-positive structures may be caused by degeneration of terminal or distal axons of this pathway. NFT and LB also had a somewhat orderly distribution with reference to this pathway.