Article

The neuropharmacology of L-theanine(N-ethyl-L-glutamine): A possible neuroprotective and cognitive enhancing agent

Behavioural Neuroscience Laboratory, Department of Physiology, Monash Center for Brain and Behaviour, Monash University, Australia.
Journal of Herbal Pharmacotherapy 02/2006; 6(2):21-30. DOI: 10.1080/J157v06n02_02
Source: PubMed

ABSTRACT L-theanine (N-ethyl-L-glutamine) or theanine is a major amino acid uniquely found in green tea. L-theanine has been historically reported as a relaxing agent, prompting scientific research on its pharmacology. Animal neurochemistry studies suggest that L-theanine increases brain serotonin, dopamine, GABA levels and has micromolar affinities for AMPA, Kainate and NMDA receptors. In addition has been shown to exert neuroprotective effects in animal models possibly through its antagonistic effects on group 1 metabotrophic glutamate receptors. Behavioural studies in animals suggest improvement in learning and memory. Overall, L-theanine displays a neuropharmacology suggestive of a possible neuroprotective and cognitive enhancing agent and warrants further investigation in animals and humans.

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    • "). Remarkably, EGCG decreases Aβ levels and plaques in mice, reduced Aβ mediated cognitive impairment and modulates tau pathology in Alzheimer transgenic mice (Lee et al. 2009; Rezai-Zadeh et al. 2005, 2008), as well as prevents Aβ-induced mitochondrial dysfunction, impairment of NMDA Ca 2+ influx and ROS production (He et al. 2011). In addition to tea catechins, theanine, which is an amino acid uniquely found in tea leaf, may also possess neuroprotective effect (Nathan et al. 2006), probably by its antagonistic effect on ionotropic glutamate receptor subtypes, such as NMDARs (Kakuda 2011). Moreover , the beneficial effects of caffeine on stress-induced memory disturbance are mimicked by antagonists of adenosine A2a receptors, likely mediated by its ability to control glutamatergic transmission, especially NMDAR-dependent plasticity (Cunha and Agostinho 2010). "
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    • "L-Theanine was originally found in green tea and has historically been recognized as a relaxing agent (de Mejia et al. 2009; Nathan et al. 2006). Besides its similar chemical structure to glutamate, L-theanine shows micromolar affinities for kainate, α-amino-3-hydroxy-5-methyl-4-isoxazole- propionic acid (AMPA), and N-methyl D-aspartate (NMDA) glutamate receptors (Kakuda et al. 2002). "
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    Psychiatry and Clinical Neurosciences 12/2013; 68(5). DOI:10.1111/pcn.12134 · 1.62 Impact Factor
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    • "L-theanine (γ-glutamylet-hylamide) is a major component accounting for 40~60% of the total amino acid in green tea (Juneja et al, 1999). Since it is a neurotransmitter with neuroprotective effects, there are many reports about its pharmacodynamics in the neuroscientific field (Cho et al, 2008; Kimura et al, 2007; Nathan et al, 2006; Park et al, 2011). In the immunological filed, administration of L-theanine together with L-cystine has been shown to induce a significant increase of endogenous antioxidant levels in the liver, and antigen-specific IgG antibody and T helper cytokine in serum of animal models (Bukowski and Percival, 2008; Kurihara et al, 2007). "
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