Possible implication of hippocampal cholinergic neurostimulating peptide (HCNP)-related components in Hirano body...

We have previously demonstrated that hippocampal cholinergic neurostimulating peptide (HCNP)-related components accumulate in almost all Hirano bodies in Sommer's sector of the hippocampus of elderly individuals, and that the number of HCNP-positive Hirano bodies is greater in patients with Alzheimer's disease. Although Hirano bodies occur preferentially in the neuronal processes of the stratum pyramidale of the hippocampus, they can be seen occasionally as small inclusions, intermingled with neurofibrillary tangles and in association with senile plaques. Here we show that the small inclusions are also recognized by an anti-HCNP antibody, and by using immunoelectron microscopy demonstrate that these HCNP-positive inclusions, intermingled with tau protein-positive neurofibrillary tangles and beta-amyloid-positive senile plaques are indeed Hirano bodies. These findings strongly suggest that HCNP-related components may be involved in Hirano body formation.