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The Decarboxylation of DOPA in the Parkinsonian Brain: In vivo Studies on an Animal Model

  • F. Hefti
  • E. Melamed
  • R. J. Wurtman
Part of the Journal of Neural Transmission book series (NEURAL SUPPL, volume 16)

Summary

The site of decarboxylation of exogenously administered L-DOPA was studied in corpora striata of rats with near-total unilateral nigrostriatal lesions. After DOPA administration, the absolute increases in dopamine (DA) levels were lower in lesioned than in unlesioned striata, suggesting that, in the intact striatum, a major part of exogenous DOPA is decarboxylated in DA neurons. DOPA can also be decarboxylated outside DA neurons, however, as shown by our finding that relatively higher DOPA decarboxylase than tyrosine hydroxylase activity or DA concentration remains in striata after the nigrostriatal lesions. Also, the percentage increases in DA formation after DOPA administration were much higher in lesioned than in control striata. Rats with both raphé and nigrostriatal lesions failed to exhibit further reductions in striatal DOPA decarboxylase activity or diminished biochemical or behavioral (turning behavior) reactions to DOPA. Inhibition of the DOPA decarboxylase contained in brain capillary endothelial cells did not abolish DA formation in lesioned striata or circling behavior after DOPA administration. These findings all suggest an additional cell type in the striatum as the site of DOPA’s decarboxylation in the absence of DA neurons.

Keywords

Tyrosine Hydroxylase Kainic Acid Medial Forebrain Bundle Lesion Side Brain Capillary Endothelial Cell 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag 1980

Authors and Affiliations

  • F. Hefti
    • 1
  • E. Melamed
    • 1
  • R. J. Wurtman
    • 1
    • 2
  1. 1.Laboratory of Neuroendocrine Regulation, Department of Nutrition and Food ScienceMassachusetts Institute TechnologyCambridgeUSA
  2. 2.Laboratory of Neuroendocrine RegulationMassachusetts Institute of TechnologyCambridgeUSA

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