Alzheimer's Disease Brain-Derived Amyloid-β-Mediated Inhibition of LTP In Vivo Is Prevented by Immunotargeting Cellular Prion Protein

Synthetic amyloid-beta protein (A beta) oligomers bind with high affinity to cellular prion protein (PrPC), but the role of this interaction in mediating the disruption of synaptic plasticity by such soluble A beta in vitro is controversial. Here we report that intracerebroventricular injection of A beta-containing aqueous extracts of Alzheimer's disease (AD) brain robustly inhibits long-term potentiation (LTP) without significantly affecting baseline excitatory synaptic transmission in the rat hippocampus in vivo. Moreover, the disruption of LTP was abrogated by immunodepletion of A beta. Importantly, intracerebroventricular administration of antigen-binding antibody fragment D13, directed to a putative A beta-binding site on PrPC, prevented the inhibition of LTP by AD brain-derived A beta. In contrast, R1, a Fab directed to the C terminus of PrPC, a region not implicated in binding of A beta, did not significantly affect the A beta-mediatedinhibition of LTP. These data support the pathophysiological significance of SDS-stable A beta dimer and the role of PrPC in mediating synaptic plasticity disruption by soluble A beta.