title: Dopamine reduction in the substantia nigra of Parkinson's disease patients confirmed by in vivo magnetic resonance spectroscopic imaging.
abstract: OBJECTIVE
  Metabolic changes in the substantia nigra of patients with Parkinson's disease were previously investigated in different molecular-pathological examinations. The aim of our study was the in vivo measurement of these alterations using three-dimensional magnetic resonance spectroscopic imaging.
  
  
  METHODS
  21 patients with Parkinson's disease and 24 controls were examined using magnetic resonance spectroscopic imaging at 3 Tesla. The spectra of rostral and caudal substantia nigra regions were analyzed using LCModel. For spectral fitting, an adjusted basis data set with pathology-specific metabolites and macromolecules was used to better reproduce the in vivo spectra. To assess differences between both groups more accurately, especially in metabolites at lower concentrations, group-averaged spectra were evaluated in addition to the analysis of individual data.
  
  
  RESULTS
  We found significantly decreased N-acetylaspartate, choline, creatine, myo-inositol, glutathione and dopamine concentrations in patients with Parkinson's disease compared to controls, whereas glutamine+glutamate, γ-aminobutyric acid, and homovanillic acid were slightly increased. According to anatomical features, clear differences in the biochemical profiles were found between rostral and caudal substantia nigra voxels in both groups.
  
  
  CONCLUSIONS
  Reduced N-acetylaspartate and dopamine concentrations result from progressive degeneration of dopamine-producing neurons within the substantia nigra pars compacta. Decreased creatine levels can be interpreted as impaired energy metabolism due to mitochondrial dysfunction. Lower glutathione concentrations might be a cause or consequence of oxidative stress. Furthermore, slightly increased glutamine+glutamate and γ-aminobutyric acid levels are expected based on post mortem data in Parkinson's disease. To the best of our knowledge, this is the first non-invasive confirmation of these metabolic changes.
authors.affiliation: Department of Diagnostic and Interventional Neuroradiology, Magnetic Resonance Research Group, University Hospital Tübingen, Tübingen, Germany.
authors.forename: Adriane
authors.initials: A
authors.lastname: Gröger
authors.affiliation: Department of Diagnostic and Interventional Neuroradiology, Magnetic Resonance Research Group, University Hospital Tübingen, Tübingen, Germany.
authors.forename: Rupert
authors.initials: R
authors.lastname: Kolb
authors.affiliation: Department of Diagnostic and Interventional Neuroradiology, Magnetic Resonance Research Group, University Hospital Tübingen, Tübingen, Germany.
authors.forename: Rita
authors.initials: R
authors.lastname: Schäfer
authors.affiliation: Department of Diagnostic and Interventional Neuroradiology, Magnetic Resonance Research Group, University Hospital Tübingen, Tübingen, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Klose
mesh_terms: D000368:Aged; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D016022:Case-Control Studies; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D010300:Parkinson Disease / Q000378:metabolism*; D013378:Substantia Nigra / Q000378:metabolism*
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline; D004298:Dopamine