Metabolism of Theanine, γ-Glutamylethylamide, in Rats

Unno, Toshihiro; Suzuki, Yuko; Kakuda, Takami; Hayakawa, T.; Tsuge, Haruhito

doi:10.1021/jf981113t

Cited by 102 publications

(67 citation statements)

References 24 publications

(22 reference statements)

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“…Previously, we detected theanine after intragastrical administration in various rat tissues such as serum, liver and brain (Terashima et al 1999). Some reports suggested that theanine might be degraded via glutamic acid because its structure is similar to glutamic acid, and it was suggested that enzymatic hydrolysis of theanine to glutamic acid and ethylamine was accomplished in the kidney (Unno et al 1999) (Fig. 1).…”

Section: Introductionmentioning

confidence: 92%

Theanine, γ-glutamylethylamide, a unique amino acid in tea leaves, modulates neurotransmitter concentrations in the brain striatum interstitium in conscious rats

et al. 2008

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Theanine (c-glutamylethylamide) is one of the major amino acid components in green tea and can pass through the blood-brain barrier. Recent studies suggest that theanine affects the mammalian central nervous system; however, the detailed mechanism remains unclear. In this study, we demonstrated the effect of theanine on neurotransmission in the brain striatum by in vivo brain microdialysis. Theanine injection into the rat brain striatum did not increase the concentration of excitatory neurotransmitters in the perfusate. On the other hand, theanine injection increased the concentration of glycine in the perfusate. Because it has been reported that theanine promotes dopamine release in the rat striatum, we investigated the glycine and dopamine concentrations in the perfusate. Co-injection of glycine receptor antagonist, strychnine, reduced theanine-induced changes in dopamine. Moreover, AMPA receptor antagonist, which regulates glycine and GABA release from glia cells, inhibited these effects of theanine and this result was in agreement with the known inhibitory effect of theanine at AMPA receptors.

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Section: Introductionmentioning

confidence: 92%

Theanine, γ-glutamylethylamide, a unique amino acid in tea leaves, modulates neurotransmitter concentrations in the brain striatum interstitium in conscious rats

et al. 2008

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“…In addition, many animal studies showed that tea flavan-3-ols are able to cross the blood-brain barrier Bastianetto et al, 2005). Previous experiments hold that γ-aminobutyric acid (GABA) and L-theanine are also able to across the blood-brain barrier (Unno et al, 1999;Jäger and Saaby, 2011;da Silva Pinto, 2013).…”

Section: Prevention Of Neurodegenerative Diseasesmentioning

confidence: 99%

Tea and human health: biomedical functions of tea active components and current issues

Chen

Zhi

2015

J. Zhejiang Univ. Sci. B

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Originating in China, tea and tea planting have spread throughout the world since the middle of the Tang dynasty. Now people from 160 countries in the world are accustomed to tea drinking. A brief history of tea's medicinal role in China and its spread to the world are introduced. The effectiveness of tea active components and tea drinking on major human diseases, including cancer, metabolic syndrome, cardiovascular disease, and neurodegenerative diseases, is discussed. Also presented are some related issues, such as the bioavailability of tea active components, the new formulations of tea polyphenols, and the safety for consumers of dietary supplements containing tea polyphenols.

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“…One example is an amino acid found in tea (theanine) which could act as a neurotransmitter. A study in rats found that theanine modulated serotonin and dopamine levels and appeared to improve memory and learning ability (Unno et al, 1999). Work on humans is needed to confirm this finding.…”

Section: Mood and Mental Performancementioning

confidence: 99%

Black tea – helpful or harmful? A review of the evidence

Ruxton²,

2006

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Objective: To consider whether consumption of black tea has a positive or negative impact on health. Design: Databases were searched for relevant epidemiological and clinical studies published between 1990 and 2004. Results: Clear evidence was found for coronary heart disease (CHD), where an intake of X3 cups per day related to risk reduction. The mechanism could involve the antioxidant action of tea polyphenols. While experimental models have suggested that flavonoids attenuated cancer risk, epidemiological studies failed to demonstrate a clear effect for tea, although there is moderate evidence for a slightly positive or no effect of black tea consumption on colorectal cancer. Studies on cancer were limited by sample sizes and insufficient control of confounders. There is moderate evidence suggestive of a positive effect of black tea consumption on bone mineral density although studies were few. There is little evidence to support the effect of tea on dental plaque inhibition but evidence to support the contribution of tea to fluoride intakes and thus theoretical protection against caries. There was no credible evidence that black tea (in amounts typically consumed) was harmful. Normal hydration was consistent with tea consumption when the caffeine content was o250 mg per cup. A moderate caffeine intake from tea appeared to improve mental performance, although sample sizes were small. There was no evidence that iron status could be harmed by tea drinking unless populations were already at risk from anaemia. Conclusions: There was sufficient evidence to show risk reduction for CHD at intakes of X3 cups per day and for improved antioxidant status at intakes of one to six cups per day. A maximum intake of eight cups per day would minimise any risk relating to excess caffeine consumption. Black tea generally had a positive effect on health. Sponsorship: The Tea Council. The authors confirm that the sponsors played no role in the writing of this review.

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Metabolism of Theanine, γ-Glutamylethylamide, in Rats

Cited by 102 publications

References 24 publications

Theanine, γ-glutamylethylamide, a unique amino acid in tea leaves, modulates neurotransmitter concentrations in the brain striatum interstitium in conscious rats

Theanine, γ-glutamylethylamide, a unique amino acid in tea leaves, modulates neurotransmitter concentrations in the brain striatum interstitium in conscious rats

Tea and human health: biomedical functions of tea active components and current issues

Black tea – helpful or harmful? A review of the evidence

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