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Enhancement of in Vivo Dopamine Release from the Rat Striatum by 6R-L-Erythro-5,6,7,8-Tetrahydrobiopterin as Studied by Brain Dialysis

  • Kunio Koshimura
  • Soichi Miwa
  • Ken Lee
  • Motohatsu Fujiwara
  • Yasuyoshi Watanabe
Part of the Advances in Behavioral Biology book series (ABBI, volume 38A)

Abstract

6R-L-erythro-5,6,7,8-Tetrahydrobiopterin (6R-BH4) is a natural cofactor for tyrosine hydroxylase, a rate-limiting enzyme for biosynthesis of catecholamines (Nagatsu et al., 1964). Since the concentration of 6R-BH4 in the brain (Fukushima and Nixon, 1980) is low compared with Km values of tyrosine hydroxylase (Nelson and Kaufman, 1987), tissue levels of 6R-BHA are considered to regulate the activity in vivo of this enzyme. Our previous findings that intracerebroventricular administration of 6R-BH4 resulted in enhanced tyrosine hydroxylation in the rat brain (Miwa et al., 1985) supported this possibility. In the same report, increases in the content of metabolites of dopamine, which is an index of the activity of dopaminergic neuron, was noted. Furthermore, administration of 6R-BH4 has been reported to improve clinical symptoms of Parkinson’s disease (Cutius et al., 1984). These data taken together suggest that 6R-BH4 enhances release of catecholamine from nerve terminals. Therefore, in the present study, the effects of 6R-BH4 on dopamine release in vivo was investigated using a brain dialysis method.

Keywords

Tyrosine Hydroxylase Dopamine Release Ringer Solution Dopamine Level Perfusion Fluid 
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

© Plenum Press, New York 1990

Authors and Affiliations

  • Kunio Koshimura
    • 1
  • Soichi Miwa
    • 1
  • Ken Lee
    • 1
  • Motohatsu Fujiwara
    • 1
  • Yasuyoshi Watanabe
    • 2
  1. 1.Department of PharmacologyKyoto University Faculty of MedicineKyotoJapan
  2. 2.Department of NeuroscienceOsaka Bioscience InstituteOsakaJapan

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