Effect of theanine, r-glutamylethylamide, on brain monoamines and striatal dopamine release in conscious rats
Yokogoshi H, Kobayashi M, Mochizuki M, Terashima T.
School of Food and Nutritional Sciences,
The University of Shizuoka,
Yada, Shizuoka, Japan.
Neurochem Res. 1998 May;23(5):667-73


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.
Green tea
Iron deficiency
Calcium and mood
Vitamins and mood
The science of dieting
Docosahexaenoic acid
Catecholamine depletion
Bad moods and sick hearts
Ascorbic acid, mood, and sex
Functional foods and the GI tract

Go To Good Drug Guide
BLTC Research
Utopian Surgery?
The Good Drug Guide
The Hedonistic Imperative
MDMA/Ecstasy: Utopian Pharmacology
Critique of Aldous Huxley's Brave New World