An intraperitoneally administered pentapeptide protects against Aβ1-42 induced neuronal excitation in vivo

The underlying cause of Alzheimer's disease (AD) is thought to be the accumulation and aggregation of a misfolded protein, amyloid-β (Aβ). A promising strategy against AD is the application of protective, peptide-based neuroprotective agents that selectively bind to Aβ. We recently described a pentapeptide, LPYFDa, which recognizes Aβ1−42 and protects neurons against the toxic effects of aggregated Aβ1−42 both in vitro and in vivo. Our previous work indicated that the in vivo ejection of fibrillar Aβ1−42 into the hippocampal CA1 region resulted in a massive increase in the NMDA-evoked neuronal firing rate. Our current aim was to study whether intraperitoneally administered LPYFDa is capable of protecting against the synaptotoxic action of fibrillar Aβ1−42 administered by iontophoresis. Our investigations of the in vivo biodistribution of tritium-labelled LPYFDa and single-unit electrophysiology revealed that LPYFDa readily crosses the blood-brain barrier, and protects the synapses against the excitatory action of fibrillar Aβ1−42 in a relatively wide temporal window in rat. This pentapeptide may serve as a lead compound for the design of novel drug candidates for the prevention of AD.