Anxiolytic Effect of a Combination of Green Tea Extract and L-theanine / 한국실험동물학회지

ABSTRACT

The purpose of this study is to investigate whether the combination of green tea extract (GTE) and L-theanine has an anxiolytic effect by oral administration through behavioral tests and neurtransmitters (or hormone) anaylses. Four week oral administration of GTE (24 mg/kg), L-theanine (4 mg/kg) or their combination showed anxiety-reducing effects determined by increasing numbers of head-dips in a hole board test and reducing retention time in a rota-rod test without changing spontaneous locomotor activity. Biochemical analyses indicated that the test materials decreased dopamine (DA), noradrenaline (NA), corticosterone (CS) and increased serotonin (5-HT) levels in brain cortex, hippocampus, and striatum, which suggests a possible mechanism of previous behavioral tests. Although the synergistic effects of GTE and L-theanine combination were not observed on the behavioral test, its effects on neurotransmitters (NA, CS) were synergistic and comparable to diazepam (2 mg/kg i.p.) with much less muscle relaxation side effect. Therefore, a combination of GTE and L-theanine may be useful as a functional food ingredient having an anxiolytic effect.