Competition between 11C-raclopride and endogenous dopamine in Parkinson's disease.

Abstract

OBJECTIVE:

The aim of this study was to understand whether the increase in 11C-raclopride binding in the striatum of patients with Parkinson's disease (PD) is associated with the depletion of endogenous dopamine.

METHODS:

Positron emission tomography (PET) scans of the two dopamine D2 receptor ligands, 11C-raclopride and 11C-N-methylspiperone (11C-NMSP), and the dopamine transporter ligand, 11C-2beta-carbomethoxy-3beta-(4-fluorophenyl)-tropane, were performed on five patients with PD and seven controls. The binding of each tracer was calculated by using a (region-cerebellum)/cerebellum ratio in the caudate, anterior putamen, and posterior putamen.

RESULTS:

In patients with PD, the 11C-raclopride to 11C-NMSP ratios in the posterior putamen, which was the subregion of the striatum with the lowest binding of 11C-2beta-carbomethoxy-3beta-(4-fluorophenyl)-tropane, were the largest among all three subregions of the striatum. In controls, the 11C-raclopride to 11C-NMSP ratios in all three subregions of the striatum were within a constant range.

CONCLUSION:

In patients with PD, the kinetic difference between 11C-raclopride and 11C-NMSP was found prominently in the posterior putamen, in which presynaptic degeneration occurred most profoundly. Therefore, we concluded that the increase in 11C-raclopride binding in the striatum of patients with PD was strongly associated with the depletion of endogenous dopamine. 11C-NMSP can be chosen in the place of 11C-raclopride in cases in which it may be essential to eliminate the influence of endogenous dopamine.

• Authors: Kenji Ishibashi, Kenji Ishii, Keiichi Oda, Hidehiro Mizusawa, Kiichi Ishiwata
• Journal: Nuclear medicine communications (Nucl Med Commun) Vol. 31 Issue 2 Pg. 159-66 (Feb 2010) ISSN: 1473-5628 [Electronic] England
• PMID: 19966595 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Carbon Radioisotopes
• Nortropanes
• 2-carbomethoxy-3-(4-fluorophenyl)nortropane
• Raclopride
• Spiperone
• 3-N-methylspiperone
• Dopamine

Topics

• Aged
• Binding, Competitive
• Carbon Radioisotopes
• Case-Control Studies
• Dopamine (metabolism)
• Female
• Humans
• Linear Models
• Male
• Middle Aged
• Neostriatum (metabolism)
• Nortropanes (metabolism)
• Parkinson Disease (diagnostic imaging, metabolism, pathology)
• Positron-Emission Tomography
• Raclopride (metabolism)
• Reproducibility of Results
• Retrospective Studies
• Spiperone (analogs & derivatives)
• Synapses (metabolism)