[Effects of theanine on cerebral ischemia-reperfusion injury in rats].

Objective: To study the protective effect of theanine on cerebral ischemia-reperfusion injury induced by focal cerebral ischemia in rats.

Method: Sprague-Dawley rats were randomly assigned into five groups: model group, shame (SH) control group and 3 theanine groups (Th-L,Th-M and Th-H). The rats in model and SH groups were given distilled water, and the rats in Th groups were given theanine solution (10, 30 and 90 mg/kg respectively) intragastrically for 15 days. Then the cerebral ischemia-reperfusion injury was established by middle cerebral artery occlusion (MCAO) in the model and Th groups, and SH group was used as a fake surgery control. The score of neurological behavior was evaluated at the 3rd and 24th hours after reperfusion. Rats were sacrificed at 24h after reperfusion, and the brain index was measured. The concentrations of aspartic acid (Asp), glutamic acid (Glu), glycine (Gly), gamma-aminobutyricacid (GABA) and theanine (The) in rat brain following ischemia-reperfusion were determined. The expressions of BDNF mRNA and Bcl-2 mRNA in hippocampi were examined by reverse transcription polymerase chain reaction (RT-PCR) technique.

Results: Compared with model control group, the neurological deficits of theanine treated groups were milder; and the symptoms were more gently. The concentration of neurotransmitter Asp was lower while the Gly and GABA were higher, and a trend of dose-effect relation was existed. The expressions of BDNF mRNA and Bcl-2 mRNA in hippocampi were up-regulated in the theanine treated groups compared with model group (P < 0.05).

Conclusion: Theanine has a protective effect on cerebral ischemia-reperfusion injury in rats, which may be associated with its interaction with amino acid neurotransmitters and up-regulating the expression of BDNF mRNA and Bcl-2 mRNA.