Plaque-induced abnormalities in neurite geometry in transgenic models of Alzheimer disease: Implications for neural system disruption

Ricky Le, Luis Cruz, Brigita Urbanc, Roger B. Knowles, Karen Hsiao-Ashe, Karen Duff, Michael C. Irizarry, H. Eugene Stanley, Bradley T. Hyman

Research output: Contribution to journalArticlepeer-review

81 Scopus citations

Abstract

Neurites that pass through amyloid-β deposits in Alzheimer disease (AD) undergo 3 changes: they develop phosphorylated tau immunoreactivity; the density of SMI-32-positive dendrites diminishes; and they also develop a marked alteration in their geometric features, changing from being nearly straight to being quite curvy. The extent to which the latter 2 phenomena are related to phosphorylated tau is unknown. We have now examined whether amyloid-β deposits in APP695Sw transgenic mice, which have only rare phosphorylated tau containing neurites, develop these changes. We found that dendritic density is diminished within the boundaries of amyloid-β plaques, with the greatest loss (about 80%, p < 0.001) within the boundaries of thioflavine S cores. Remaining dendrites within plaques develop substantial morphological alterations quantitatively similar to those seen in AD. A statistically significant but smaller degree of change in geometry was seen in the immediate vicinity around plaques, suggesting a propagation of cytoskeletal disruption from the center of the plaque outward. We examined the possible physiological consequences of this change in dendritic geometry using a standard cable-theory model. We found a predicted delay of several milliseconds in about one quarter of the dendrites passing through a thioflavine S plaque. These results are consistent with previous observations in AD, and suggest that thioflavine S-positive amyloid-β deposits have a marked effect on dendritic microarchitecture in the cortex, even in the relative absence of phosphorylated tau alterations.

Original languageEnglish (US)
Pages (from-to)753-758
Number of pages6
JournalJournal of neuropathology and experimental neurology
Volume60
Issue number8
DOIs
StatePublished - 2001

Keywords

  • Alzheimer disease
  • Modeling
  • Neural networks
  • Senile plaque
  • Transgenic

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