Neurochemical Research

, Volume 23, Issue 5, pp 667–673

Effect of Theanine, r-Glutamylethylamide, on Brain Monoamines and Striatal Dopamine Release in Conscious Rats

  • Hidehiko Yokogoshi
  • Miki Kobayashi
  • Mikiko Mochizuki
  • Takehiko Terashima
Article

DOI: 10.1023/A:1022490806093

Cite this article as:
Yokogoshi, H., Kobayashi, M., Mochizuki, M. et al. Neurochem Res (1998) 23: 667. doi:10.1023/A:1022490806093

Abstract

Theanine, r-glutamylethylamide, is one of the major components of amino acids in Japanese green tea. Effect of theanine on brain amino acids and monoamines, and the striatal release of dopamine (DA) was investigated. Determination of amino acids in the brain after the intragastric administration of theanine showed that theanine was incorporated into brain through blood-brain barrier via leucine-preferring transport system. The concentrations of norepinephrine, 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindole acetic acid (5HIAA) in the brain regions were unaffected by the theanine administration except in striatum. Theanine administration caused significant increases in serotonin and/or DA concentrations in the brain, especially in striatum, hypothalamus and hippocampus. Direct administration of theanine into brain striatum by microinjection caused a significant increase of DA release in a dose-dependent manner. Microdialysis of brain with calcium-free Ringer buffer attenuated the theanine-induced DA release. Pretreatment with the Ringer buffer containing an antagonist of non-NMDA (N-methyl-D-aspartate) glutamate receptor, MK-801, for 1 hr did not change the significant increase of DA release induced by theanine. However, in the case of pretreatment with AP-5, (±)-2-amino-5-phosphonopentanoic acid; antagonist of NMDA glutamate receptor, the theanine-induced DA release from striatum was significantly inhibited. These results suggest that theanine might affect the metabolism and/or the release of some neurotransmitters in the brain, such as DA.

Theanineserotonindopaminemicrodialysisglutamate receptorNMDA receptor

Copyright information

© Plenum Publishing Corporation 1998

Authors and Affiliations

  • Hidehiko Yokogoshi
    • 2
  • Miki Kobayashi
    • 1
  • Mikiko Mochizuki
    • 1
  • Takehiko Terashima
    • 1
  1. 1.School of Food and Nutritional SciencesThe University of ShizuokaYada, ShizuokaJapan
  2. 2.Laboratory of Nutritional Biochemistry, School of Food and Nutritional SciencesThe University of ShizuokaYada, ShizuokaJapan