Early loss of dendritic spines in murine scrapie revealed by confocal analysis.

Confocal analysis of dye-filled neurons has revealed a significant early loss of dendritic spines in a murine scrapie model in which neuron loss occurs in the hippocampus. An 18% loss of spines was found at 109 days, > 50 days before neuron loss occurs, and by 126 days a 51% spine loss was found. Spine loss is concurrent with synapse loss, axon terminal degeneration and a decrease in long term potentiation in this model. Preceding these changes is the deposition of disease specific PrP at 70 days, which may initiate the damage to dendritic spines and the subsequent degeneration of synapses. We suggest that these changes underlie the development of clinical disease in the transmissible spongiform encephalopathies.