A strategy for the study of cerebral amino acid transport using iodine-123-labeled amino acid radiopharmaceutical: 3-iodo-alpha-methyl-L-tyrosine.
We examined the brain accumulation of iodine-123-iodo-alpha-methyl-L-tyrosine (123I-L-AMT) in mice and rats. I-L-AMT showed high brain accumulation in mice, and in rats; rat brain uptake index exceeded that of 14C-L-tyrosine. The brain uptake index and the brain slice studies indicated the affinity of I-L-AMT for carrier-mediated and stereoselective active transport systems, respectively; both operating across the blood-brain barrier and cell membranes of the brain. The tissue homogenate analysis revealed that most of the accumulated radioactivity belonged to intact I-L-AMT, an indication of its stability. Thus, 123I-L-AMT appears to be a useful radiopharmaceutical for the selective measurement of cerebral amino acid transport.
Kawai
K
K
Faculty of Pharmaceutical Sciences, Science University of Tokyo, Japan.
Fujibayashi
Y
Y
Saji
H
H
Yonekura
Y
Y
Konishi
J
J
Kubodera
A
A
Yokoyama
A
A
D000596:Amino Acids / Q000493:pharmacokinetics*; D000818:Animals; D001692:Biological Transport; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D007457:Iodine Radioisotopes; D008297:Male; D008781:Methyltyrosines; D051379:Mice; D011877:Radionuclide Imaging; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution; D014443:Tyrosine / Q000493:pharmacokinetics
D000596:Amino Acids; D007457:Iodine Radioisotopes; D008781:Methyltyrosines; D014443:Tyrosine; C030855:3-iodo-alpha-methyltyrosine