Oral intake of γ-aminobutyric acid affects mood and activities of central nervous system during stressed condition induced by mental tasks
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γ-Aminobutyric acid (GABA) is a kind of amino acid contained in green tea leaves and other foods. Several reports have shown that GABA might affect brain protein synthesis, improve many brain functions such as memory and study capability, lower the blood pressure of spontaneously hypertensive rats, and may also have a relaxation effect in humans. However, the evidence for its mood-improving function is still not sufficient. In this study, we investigated how the oral intake of GABA influences human adults psychologically and physiologically under a condition of mental stress. Sixty-three adults (28 males, 35 females) participated in a randomized, single blind, placebo-controlled, crossover-designed study over two experiment days. Capsules containing 100 mg of GABA or dextrin as a placebo were used as test samples. The results showed that EEG activities including alpha band and beta band brain waves decreased depending on the mental stress task loads, and the condition of 30 min after GABA intake diminished this decrease compared with the placebo condition. That is to say, GABA might have alleviated the stress induced by the mental tasks. This effect also corresponded with the results of the POMS scores.
Keywordsγ-Aminobutyric acid Electroencephalogram Acute stress Profile of Mood States
Central nervous system
Autonomic nervous system
Arithmetic mental task
Auditory oddball target detection task
Profile of Mood States
Visual analogue scales
This work was supported in part by grants from the Collaboration of Regional Entities for the Advancement of Technological Excellence (CREATE), research funds provided by the Japan Society and Technology Agency (JST), and a Grant-in-Aid for Scientific Research (B) provided by the Japan Society for the Promotion of Sciences (JSPS) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
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