Department of Mental Disorder Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8502, Japan.
Department of Advanced Neuroimaging, Integrative Brain Imaging Center, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8502, Japan.
Psychopharmacology (Berl). 2018 Jan;235(1):37-45. doi: 10.1007/s00213-017-4743-1. Epub 2017 Oct 3.
The amino acid L-theanine (N-ethyl-L-glutamine) has historically been considered a relaxing agent. In the present study, we examined the effects of repeated L-theanine administration on behavior, levels of amino acids in the cerebrospinal fluid (CSF), and hippocampal activity in Wistar Kyoto (WKY) rats, an animal model of anxiety and depressive disorders.
Behavioral tests were performed after 7-10 days of L-theanine (0.4 mg kg day) or saline administration, followed by CSF sampling for high-performance liquid chromatography (HPLC) analysis. An independent set of animals was subjected to [F]fluorodeoxyglucose positron emission tomography (PET) scanning after the same dose of L-theanine or saline administration for 7 days.
In the elevated plus maze test, the time spent in the open arms was significantly longer in the L-theanine group than in the saline group (P = 0.035). In addition, significantly lower CSF glutamate (P = 0.039) and higher methionine (P = 0.024) concentrations were observed in the L-theanine group than in the saline group. A significant increase in the standard uptake value ratio was observed in the hippocampus/cerebellum of the L-theanine group (P < 0.001).
These results suggest that L-theanine enhances hippocampal activity and exerts anxiolytic effects, which may be mediated by changes in glutamate and methionine levels in the brain. Further study is required to more fully elucidate the mechanisms underlying the effects of L-theanine.
氨基酸 L-茶氨酸（N-乙基-L-谷氨酰胺）历来被认为是一种放松剂。在本研究中，我们研究了重复给予 L-茶氨酸对 Wistar Kyoto（WKY）大鼠行为、脑脊液（CSF）中氨基酸水平和海马活动的影响，WKY 大鼠是焦虑和抑郁障碍的动物模型。
在给予 L-茶氨酸（0.4mg/kg/天）或生理盐水 7-10 天后进行行为测试，随后进行高效液相色谱（HPLC）分析 CSF 取样。一组独立的动物在给予相同剂量的 L-茶氨酸或生理盐水 7 天后接受 [F]氟脱氧葡萄糖正电子发射断层扫描（PET）扫描。
在高架十字迷宫测试中，L-茶氨酸组在开放臂上花费的时间明显长于生理盐水组（P=0.035）。此外，L-茶氨酸组 CSF 谷氨酸（P=0.039）浓度显著降低，蛋氨酸（P=0.024）浓度显著升高。L-茶氨酸组海马/小脑的标准摄取比值显著增加（P<0.001）。
这些结果表明，L-茶氨酸增强海马活动并发挥抗焦虑作用，这可能是通过大脑中谷氨酸和蛋氨酸水平的变化介导的。需要进一步研究以更充分阐明 L-茶氨酸作用的机制。
