PDAPP; YFP double transgenic mice: a tool to study amyloid-beta associated changes in axonal, dendritic, and synaptic...

Area of Science:

• Neuroscience
• Pathology
• Genetics

Background:

• Neuritic plaques, characterized by amyloid-beta (Abeta) peptide accumulations, are key pathological hallmarks of Alzheimer's disease (AD).
• Understanding the specific toxicity of different Abeta structural forms on neuronal processes is crucial for AD research.

Purpose of the Study:

• To investigate the neuritic toxicity of fibrillar versus non-fibrillar Abeta structures.
• To characterize the structural changes in axons and dendrites associated with Abeta deposits using a novel transgenic mouse model.

Main Methods:

• Generation of PDAPP; YFP double transgenic mice, which model AD-like pathology and allow YFP labeling of specific neurons.
• Microscopic analysis (including electron microscopy and silver staining) to examine YFP-labeled neuronal structures in proximity to Abeta deposits.
• Immunohistochemical analysis using synaptic vesicle markers, phosphorylated neurofilaments, and phosphorylated tau.

Main Results:

• Markedly enlarged, dystrophic axonal and dendritic varicosities were observed specifically around fibrillar Abeta deposits in PDAPP; YFP mice.
• These varicosities were absent in areas with non-fibrillar Abeta.
• YFP-labeled varicosities correlated with electron microscopy and silver staining findings, but were often missed by other standard staining methods for dystrophic neurites.
• Abnormal accumulation of some synaptic vesicle markers was noted in these varicosities.

Conclusions:

• Fibrillar Abeta deposits are directly associated with the formation of dystrophic neurites (axonal and dendritic varicosities).
• The PDAPP; YFP mouse model provides a valuable tool for studying neuritic pathology in AD and other neurological conditions.
• This model facilitates in vitro and in vivo investigations into the dynamics of neuronal structures in disease states.