title: Vector-mediated delivery of 125I-labeled beta-amyloid peptide A beta 1-40 through the blood-brain barrier and binding to Alzheimer disease amyloid of the A beta 1-40/vector complex.
abstract: The brain amyloid of Alzheimer disease (AD) may potentially be imaged in patients with AD by using neuroimaging technology and a radiolabeled form of the 40-residue beta-amyloid peptide A beta 1-40 that is enabled to undergo transport through the brain capillary endothelial wall, which makes up the blood-brain barrier (BBB) in vivo. Transport of 125I-labeled A beta 1-40 (125I-A beta 1-40) through the BBB was found to be negligible by experiments with both an intravenous injection technique and an internal carotid artery perfusion method in anesthetized rats. In addition, 125I-A beta 1-40 was rapidly metabolized after either intravenous injection or internal carotid artery perfusion. BBB transport was increased and peripheral metabolism was decreased by conjugation of monobiotinylated 125I-A beta 1-40 to a vector-mediated drug delivery system, which consisted of a conjugate of streptavidin (SA) and the OX26 monoclonal antibody to the rat transferrin receptor, which undergoes receptor-mediated transcytosis through the BBB. The brain uptake, expressed as percent of injected dose delivered per gram of brain, of the 125I,bio-A beta 1-40/SA-OX26 conjugate was 0.15 +/- 0.01, a level that is 2-fold greater than the brain uptake of morphine. The binding of the 125I,bio-A beta 1-40/SA-OX26 conjugate to the amyloid of AD brain was demonstrated by both film and emulsion autoradiography performed on frozen sections of AD brain. Binding of the 125I,bio-A beta 1-40/SA-OX26 conjugate to the amyloid of AD brain was completely inhibited by high concentrations of unlabeled A beta 1-40. In conclusion, these studies show that BBB transport and access to amyloid within brain may be achieved by conjugation of A beta 1-40 to a vector-mediated BBB drug delivery system.
mesh_terms: D000544:Alzheimer Disease / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000008:administration & dosage / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D000911:Antibodies, Monoclonal; D001345:Autoradiography; D001665:Binding Sites; D001692:Biological Transport; D001710:Biotin; D001812:Blood-Brain Barrier; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D002343:Carotid Artery, Internal; D004337:Drug Carriers; D006801:Humans; D007150:Immunohistochemistry; D007261:Infusions, Intra-Arterial; D007262:Infusions, Intravenous; D007457:Iodine Radioisotopes; D007700:Kinetics; D008297:Male; D010446:Peptide Fragments / Q000008:administration & dosage / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011990:Receptors, Transferrin / Q000378:metabolism
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D000911:Antibodies, Monoclonal; D004337:Drug Carriers; D007457:Iodine Radioisotopes; D010446:Peptide Fragments; D011990:Receptors, Transferrin; C078592:amyloid beta-protein (1-40); D001710:Biotin