Comparison of [123I]beta-CIT and [123I]IPCIT as single-photon emission tomography radiotracers for the dopamine transporter in nonhuman primates
| Autor: | B. Ellen Scanley, Mohammed S. Al-Tikriti, Mitchell S. Gandelman, Marc Laruelle, Yolanda Zea-Ponce, Ronald M. Baldwin, Sami S. Zoghbi, Paul B. Hoffer, Dennis S. Charney, Shayoin Wang, John L. Neumeyer, Robert B. Innis |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
Serotonin
Time Factors Metabolite Dopamine Nerve Tissue Proteins Sensitivity and Specificity Iodine Radioisotopes chemistry.chemical_compound Cocaine In vivo medicine Animals Radiology Nuclear Medicine and imaging Dopamine transporter Brain Chemistry Serotonin Plasma Membrane Transport Proteins Tomography Emission-Computed Single-Photon Dopamine Plasma Membrane Transport Proteins Membrane Glycoproteins biology business.industry Brain Membrane Transport Proteins Transporter Tropane General Medicine chemistry Lipophilicity Biophysics biology.protein Female Nuclear medicine business Carrier Proteins medicine.drug Papio |
| Zdroj: | European journal of nuclear medicine. 22(1) |
| ISSN: | 0340-6997 |
| Popis: | Single-photon emission tomographic (SPET) imaging with the radiotracer [123I]2β-carbomethoxy-3β-(4-iodophenyl)tropane ([123I]β-CIT) has been reported to be a useful in vivo measure of dopamine (DA) transporters. However, in addition to its high DA transporter affinity,β-CIT also binds with high affinity to serotonin (5-HT) transporters. 2β-Carboisopropoxy-3β-(4-iodophenyl)tropane (IPCIT) has been demonstrated by in vitro studies to have higher selectivity for the DA transporter. We compared [123I]β-CIT and [123I]IPCIT SPET imaging and plasma metabolite analyses in baboons to evaluate the potential advantages of [123I]IPCIT for quantitative in vivo measurements of DA transporter densities. Both tracers had low levels (2% of total plasma123I activity) of lipophilic radiolabeled metabolites at 420 min. [123I]IPCIT had significantly higher binding to plasma proteins. The average percent free (nonprotein bound) [123I]β-CIT and [123I]IPCIT were 52%±7% and 14%±6%, respectively. Region of interest uptake data were normalized by injected dose and body weight. Consistent with the high density of 5-HT transporters in the midbrain and the lower 5-HT transporter affinity of IPCIT, the normalized peak specific midbrain uptake of [123I]β-CIT (1.7±0.5) was higher than that of [123I]IPCIT (0.4±0.2). Consistent with its greater lipophilicity, [123I]IPCIT had higher nonspecific uptake, such that normalized cerebellar uptake of [123I]IPCIT was about twice that of [123I]β-CIT. The ratio of specific to nonspecific uptake in striatum was greater for [123I]β-CIT compared to [123I]IPCIT; however, striatal binding potentials and distribution volumes were not significantly different. In conclusion, [123I]IPCIT demonstrated in vivo a higher DA transporter selectivity and higher level of nonspecific uptake. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full text from SpringerLink