Chronic subthalamic nucleus stimulation and striatal D2 dopamine receptors in Parkinson's disease--A [(11)C]-raclopride PET study

Abstract

Context: Subthalamic nucleus (STN) stimulation mechanism of action remains a matter for debate. In animals, an increased striatal dopamine (DA) release due to STN stimulation has been reported.

Objective: To determine in Parkinson's disease (PD) patients using positron emission tomography (PET) and [11C]-Raclopride, whether STN stimulation induces a striatal DA release.

Methods: Nine PD patients with bilateral STN stimulation were enrolled and underwent two [11C]-Raclopride PET scans. The scans were randomly performed in off and on stimulation conditions. Striatal [11C]-Raclopride binding potential (BP) was calculated using regions of interest and statistical parametric mapping.

Results: For PD patients, the mean [(11C]-Raclopride BP (+/- SD) were, in Off stimulation condition: 1.7 +/- 0.3 for the right caudate nucleus, 1.8 +/- 0.4 for the left caudate nucleus, 2.6 +/- 0.5 for the right putamenand 2.6 +/- 0.5 for the left putamen. In On stimulation condition: 1.7 +/- 0.4 for the right caudate nucleus, 1.9 +/- 0.5 for the left caudate nucleus, 2.8 +/- 0.7 for the right putamen and 2.7 +/- 0.8 for the left putamen. No significant difference of BP related to the stimulation was noted.

Conclusion: STN stimulation does not produce significant variations of striatal DA release as assessed by PET and [11C]-Raclopride.