Shintaro Ogawa1, Miho Ota1, Jun Ogura1, Koichi Kato2,3, Hiroshi Kunugi4. 1. 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. 2. Department of Advanced Neuroimaging, Integrative Brain Imaging Center, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8502, Japan. 3. Department of Functional Brain Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8502, Japan. 4. 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. hkunugi@ncnp.go.jp.
Abstract
RATIONALE AND OBJECTIVES: 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. METHODS: Behavioral tests were performed after 7-10 days of L-theanine (0.4 mg kg-1 day-1) or saline administration, followed by CSF sampling for high-performance liquid chromatography (HPLC) analysis. An independent set of animals was subjected to [18F]fluorodeoxyglucose positron emission tomography (PET) scanning after the same dose of L-theanine or saline administration for 7 days. RESULTS: 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). CONCLUSIONS: 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.
RATIONALE AND OBJECTIVES: 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. METHODS: Behavioral tests were performed after 7-10 days of L-theanine (0.4 mg kg-1 day-1) or saline administration, followed by CSF sampling for high-performance liquid chromatography (HPLC) analysis. An independent set of animals was subjected to [18F]fluorodeoxyglucose positron emission tomography (PET) scanning after the same dose of L-theanine or saline administration for 7 days. RESULTS: 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). CONCLUSIONS: 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.
Authors: Daniel F Hermens; Kate M Chitty; Rico Sc Lee; Ashleigh Tickell; Paul S Haber; Sharon L Naismith; Ian B Hickie; Jim Lagopoulos Journal: J Affect Disord Date: 2015-07-26 Impact factor: 4.839
Authors: Amir Mohammadzadeh; Péter P Lakatos; Mihály Balogh; Ferenc Zádor; Dávid Árpád Karádi; Zoltán S Zádori; Kornél Király; Anna Rita Galambos; Szilvia Barsi; Pál Riba; Sándor Benyhe; László Köles; Tamás Tábi; Éva Szökő; Laszlo G Harsing; Mahmoud Al-Khrasani Journal: Int J Mol Sci Date: 2021-03-01 Impact factor: 5.923