Intranasal delivery of human beta-amyloid peptide in rats: effective brain targeting.

(1) Intranasal administration is a non-invasive and effective way for the delivery of drugs to brain that circumvents the blood-brain barrier. The aims of the study were to test a nasal delivery system for human beta-amyloid (A beta) peptides, to measure the delivery of the peptides to brain regions, and to test their biological activity in rats. (2) A beta(1-42), in the form of a mixture of oligomers, protofibrils, and fibrils was dissolved in a nasal formulation containing hydrophobic, hydrophylic, and mucoadhesive components. The peptide solution was administered intranasally to rats as a single dose or in repeated doses. (3) Nasally injected A beta labeled with the blue fluorescent dye amino-methyl coumarinyl acetic acid (AMCA) could be detected by fluorescent microscopy in the olfactory bulb and frontal cortex. The concentration of the peptide was quantified by fluorescent spectroscopy, and a significant amount of AMCA-A beta peptide could be detected in the olfactory bulb. Unlabeled A beta also reached the olfactory bulb and frontal cortex of rats as evidenced by intense immunostaining. (4) In behavioral experiments, nasal A beta treatment did not affect anxiety levels (open-field test) and short-term memory (Y-maze test), but significantly impaired long-term spatial memory in the Morris water maze. The treatments did not result in A beta immunization. (5) The tested intranasal delivery system could successfully target a bioactive peptide into the central nervous system and provides a basis for developing a non-invasive and cost effective, new model to study amyloid-induced dysfunctions in the brain.