Preparation and biodistribution of [125I]IBZP: a potential CNS D-1 dopamine receptor imaging agent.
Carrier free [125I]IBZP, R-(+)-8-[125I] iodo-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine-7-ol), was prepared from the corresponding uniodinated compound by an oxidative iodination reaction with chloramine-T and sodium [125I]iodide. After purification by column chromatography the desired uptake was obtained with a high purity (greater than 95%). The agent showed good localization in brain after i.v. injection in rats, with an uptake of 2.7, 1.2 and 0.8% dose/organ at 2, 15 and 30 min post injection, respectively. The regional distribution in rat brain, as measured by in vivo autoradiography, displayed a high uptake in the caudate putamen, accumbens nucleus and substantia nigra, regions known to have a high concentration D-1 dopamine receptors. The uptake ratio of striatum/cerebellum increased with time; at 30 s and 2 h after injection the ratio was 1.1 and 5.3, respectively. The specific uptake in the D-1 dopamine receptor regions can be blocked by pretreatment with SCH-23390, a selective D-1 dopamine receptor antagonist (SCH-23390). The corresponding iodine-123 (t1/2 = 13 h, gamma energy 159 keV) labeled agent may be suitable for SPECT imaging of CNS D-1 dopamine receptors.
Kung
H F
HF
Department of Nuclear Medicine, SUNY, Buffalo.
Billings
J J
JJ
Guo
Y Z
YZ
Blau
M
M
Ackerhalt
R
R
D000818:Animals; D001552:Benzazepines / Q000031:analogs & derivatives* / Q000493:pharmacokinetics*; D001921:Brain / Q000000981:diagnostic imaging*; D007457:Iodine Radioisotopes; D007553:Isotope Labeling / Q000379:methods; D008297:Male; D051381:Rats; D011954:Receptors, Dopamine / Q000000981:diagnostic imaging*; D017447:Receptors, Dopamine D1; D014018:Tissue Distribution; D014055:Tomography, Emission-Computed
C049558:8-iodo-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine-7-ol; D001552:Benzazepines; D007457:Iodine Radioisotopes; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1