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Dissociation of metabolic and hemodynamic levodopa responses in the 6-hydroxydopamine rat model

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Author

  • Renata P. Lerner
  • Zisis Bimpisidis
  • Stergiani Agorastos
  • Sandra Scherrer
  • Stephen L. Dewey
  • Angela Cenci Nilsson
  • David Eidelberg

Summary, in English

Dissociation of vasomotor and metabolic responses to levodopa has been observed in human subjects with Parkinson's disease (PD) studied with PET and in autoradiograms from 6-hydroxydopamine (6-OHDA) rat. In both species, acute levodopa administration was associated with increases in basal ganglia cerebral blood flow (CBF) with concurrent reductions in cerebral metabolic rate (CMR) for glucose in the same brain regions. In this study, we used a novel dual-tracer microPET technique to measure CBF and CMR levodopa responses in the same animal. Rats with unilateral 6-OHDA or sham lesion underwent sequential 15O-water (H2 15O) and 18F-fluorodeoxyglucose (FDG) microPET to map CBF and CMR following the injection of levodopa or saline. A subset of animals was separately scanned under ketamine/xylazine and isoflurane to compare the effects of these anesthetics. Regardless of anesthetic agent, 6-OHDA animals exhibited significant dissociation of vasomotor (ΔCBF) and metabolic (ΔCMR) responses to levodopa, with stereotyped increases in CBF and reductions in CMR in the basal ganglia ipsilateral to the dopamine lesion. No significant changes were seen in sham-lesioned animals. These data faithfully recapitulate analogous dissociation effects observed previously in human PD subjects scanned sequentially during levodopa infusion. This approach may have utility in the assessment of new drugs targeting the exaggerated regional vasomotor responses seen in human PD and in experimental models of levodopa-induced dyskinesia.

Publishing year

2016-12-01

Language

English

Pages

31-37

Publication/Series

Neurobiology of Disease

Volume

96

Document type

Journal article

Publisher

Elsevier

Topic

  • Neurosciences

Keywords

  • Cerebral blood flow
  • Glucose metabolism
  • Levodopa treatment
  • MicroPET
  • Parkinson's disease

Status

Published

Research group

  • Basal Ganglia Pathophysiology

ISBN/ISSN/Other

  • ISSN: 0969-9961