Inhibitory Activities Of L-Theanine Against Central Excitation Induced By Caffeine In Mice

Theanine (γ-glutamyl ethyl amide) is an amino acid contained in tea. It is not involved in protein synthesis and accounts for approximately50%of the total free amino acid content in tea,1%-2%of the dry weight. Almost all of the natural theanine is extracted from tea. L-theanine which is the main component in tea provides the sweet taste, and is known to possess many pharmacological functions, such as neuro-protection function, self-possession function, relieving fatigue, reducing blood pressure, improve their learning and memorial capabilities, enhancing the antitumor activity of doxorubicin on primary tumors and enhanced its metastasis-suppressive effects. Caffeine is the most abundant alkaloid in tea. It accounts for2%-4%of the dry weight and possess functions of antidepressant, cardiac, helping digestion. It can be used to treat mental diseases, and served as the most common nerve excitement medicine and additives in many kinds of food products.To development health protection of theanine and caffeine, it is important to clarify the absorption characteristics of theanine, caffeine and their antagonistic effects. Current reports about antagonism between theanine and caffeine are mainly based on EEG and brain waves which are indirect and ambiguous indicators. It is necessary to confirm their antagonistic effects by physiological and behavioral indicators. This paper discussed relieving fatigue by theanine and effects of theanine against central excitation induced by caffeine in mice form physiological and behavioral indicators. The results can provide more specific theoretical basis for application of theanine as functional ingredients in food industry, to develop food products with functions of improving learning and memorial capabilities.In this paper, we investigated the effects on the mice’s spontaneous activity (the times of free movement and the foreleg lift) by intake of theanine. With mice as research objects, each group of mice was given theanine in dose of lmg/kg、3mg/kg、15mg/kg、30mg/kg、80mg/kg for7days. After the last dose, the times of free movement and the foreleg lift was recorded at30min,60min,90min,120min,150min,180min, respectively. Results showed that intake of theanine alone decreased spontaneous activity of mice in dose-dependent manner in dose form1mg/kg to15mg/kg.In order to investigate the effects of theanine against central excitation induced by caffeine in mice. As the reference, mice was given5mg/kg of caffeine. The test group of mice was given each with lmg/kg,3mg/kg,15mg/kg,30mg/kg,80mg/kg of theanine and5mg/kg of caffeine at the same time for7days. After the last does, recording the times of free movement at30min,60min,90min,120min,150min,180min were recorded. Results showed that intake of caffeine alone enhanced the spontaneous activities of mice. By administration of theanine and caffeine at the same time, the spontaneous activity of mice induced by caffeine was inhibited in dose-dependent manner.In this paper, the influence of theanine on the metabolism of caffeine in blood of mice was also investigated. As the reference group, mice was given5mg/kg of caffeine. The test group of mice was given each with lmg/kg,3mg/kg,15mg/kg,30mg/kg,80mg/kg of theanine and5mg/kg of caffeine at the same time for7days. After the last does,0.2mL of blood was extracted form mice’s eyes at30min,60min,90min,120min,150min,180min, respectively. Contents of caffeine in mice blood was measured by HPLC. Results showed that theanine can affect the metabolism of caffeine in blood of mice. Caffeine was delayed to be absorbed into blood before60min, and the digesting of caffeine in blood of mice was extend before180min in dose-dependent manner.