Dissociation of metabolic and neurovascular responses to levodopa in the treatment of Parkinson's disease.

Abstract

We compared the metabolic and neurovascular effects of levodopa (LD) therapy for Parkinson's disease (PD). Eleven PD patients were scanned with both [15O]-H2O and [18F]-fluorodeoxyglucose positron emission tomography in the unmedicated state and during intravenous LD infusion. Images were used to quantify LD-mediated changes in the expression of motor- and cognition-related PD covariance patterns in scans of cerebral blood flow (CBF) and cerebral metabolic rate for glucose (CMR). These changes in network activity were compared with those occurring during subthalamic nucleus (STN) deep brain stimulation (DBS), and those observed in a test-retest PD control group. Separate voxel-based searches were conducted to identify individual regions with dissociated treatment-mediated changes in local cerebral blood flow and metabolism. We found a significant dissociation between CBF and CMR in the modulation of the PD motor-related network by LD treatment (p < 0.001). This dissociation was characterized by reductions in network activity in the CMR scans (p < 0.003) occurring concurrently with increases in the CBF scans (p < 0.01). Flow-metabolism dissociation was also evident at the regional level, with LD-mediated reductions in CMR and increases in CBF in the putamen/globus pallidus, dorsal midbrain/pons, STN, and ventral thalamus. CBF responses to LD in the putamen and pons were relatively greater in patients exhibiting drug-induced dyskinesia. In contrast, flow-metabolism dissociation was not present in the STN DBS treatment group or in the PD control group. These findings suggest that flow-metabolism dissociation is a distinctive feature of LD treatment. This phenomenon may be especially pronounced in patients with LD-induced dyskinesia.

• Authors: Shigeki Hirano, Kotaro Asanuma, Yilong Ma, Chengke Tang, Andrew Feigin, Vijay Dhawan, Maren Carbon, David Eidelberg
• Journal: The Journal of neuroscience : the official journal of the Society for Neuroscience (J Neurosci) Vol. 28 Issue 16 Pg. 4201-9 (Apr 16 2008) ISSN: 1529-2401 [Electronic] United States
• PMID: 18417699 (Publication Type: Comparative Study, Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Levodopa

Topics

• Aged
• Blood Flow Velocity (drug effects, physiology)
• Cerebrovascular Circulation (drug effects, physiology)
• Deep Brain Stimulation (methods)
• Humans
• Levodopa (pharmacology, therapeutic use)
• Middle Aged
• Parkinson Disease (drug therapy, metabolism, physiopathology)
• Positron-Emission Tomography (methods)
• Subthalamic Nucleus (drug effects, metabolism)