Taira Shu, Abe Aya, Ozeki Makoto, Shikano Hitomi, Kapoor Mahendra P, Muto Makoto, Kobayashi Shoko
Faculty of Food and Agricultural Sciences, Fukushima University, Kanayagawa, Fukushima, 960-1296, Japan.
Nutrition Division, Taiyo Kagaku Co. Ltd., Yokkaichi, Mie, 510-0844, Japan.
Sci Rep. 2025 Jul 2;15(1):23075. doi: 10.1038/s41598-025-08190-0.
L-Theanine (LT), a derivative of glutamic acid, is abundant in tea leaves and contributes to tea's umami and sweetness. In recent years, its neurological effects, notably its role in promoting relaxation, have attracted intense research interest. The purpose of this study was to elucidate the detailed mechanisms underlying the relaxation effects of LT by thoroughly investigating the dynamics of neurotransmitters in the brain using mice after LT administration. Imaging mass spectrometry (IMS) was employed to visualize changes in the catecholamine system within the brain after LT administration. Simultaneous imaging of catecholamines, such as L-dihydroxyphenylalanine, dopamine, and norepinephrine, as well as representative amino acids such as γ-aminobutyric acid, revealed dynamic variations across time. Our findings revealed links between LT administration and the modulation of both inhibitory and excitatory neurotransmission, through its influence on the GABAergic and catecholaminergic systems, following the entry of exogenous LT into the brain. This approach enhanced our understanding of the mechanisms underlying LT's effects on the brain by visualizing neurotransmitter and amino acid distribution, as well as accompanying metabolic processes, at specific time points using IMS.
L-茶氨酸（LT）是谷氨酸的衍生物，在茶叶中含量丰富，赋予茶叶鲜味和甜味。近年来，其神经学效应，尤其是在促进放松方面的作用，引起了广泛的研究兴趣。本研究的目的是通过在给小鼠注射LT后深入研究大脑中神经递质的动态变化，阐明LT产生放松效应的详细机制。采用成像质谱（IMS）技术观察LT给药后大脑中儿茶酚胺系统的变化。对L-二羟基苯丙氨酸、多巴胺和去甲肾上腺素等儿茶酚胺以及γ-氨基丁酸等代表性氨基酸进行同步成像，揭示了随时间的动态变化。我们的研究结果表明，外源性LT进入大脑后，通过影响GABA能和儿茶酚胺能系统，LT给药与抑制性和兴奋性神经传递的调节之间存在联系。这种方法通过使用IMS在特定时间点可视化神经递质和氨基酸分布以及伴随的代谢过程，加深了我们对LT对大脑影响机制的理解。
