Evaluation Of The Antidepressant Effect Of L-theanine And The Research Of Its Relevant Mechanism

The ameliorative effect of L-theanine on chronic unpredictable mild stress-induced depression in rats and the possible mechanism were investigated in our paper. L-theanine was as the raw material to intervene CUMS rats. Depending on the different hypotheses of major depression, combined with behavioral test results, to explore the antidepressant effect of L-theanine.1. The behavior influence of L-theanine on CUMS ratsSD rats were divided into control group, model group, fluoxetine group (5mg/kg), L-theanine low dose groups (5mg/kg), L-theanine middle dose groups (20mg/kg), L-theanine high dose group (100mg/kg). Modeling for35days, all of the rats were individually feeding except the control group. The rats were provoked by two randomly stressor every day. It includes fasting, dehydrated, flash lights, tilt, reverse day and night, noise, wet cages, bondage, clamp the tail. During the35days, the weight and intake were measured and the sucrose preference test was measured every week. After the modeled, the open-field test, force swim test and light/dark test were examined. The results showed that, compared with control group, the percentage of sucrose preference, the numbers of crossing and rearing, and the number of entries into light box and total duration time in model group were very significantly lower, which demonstrated the model was successfully established. Compared to the model group, the behavior of CUMS-induced depression was significantly ameliorated by the administration of L-theanine, especially that with high dose.2. Research on the effects of L-theanine on related biochemical indexes of CUMS ratsAfter the behavior experiment, the rats were picked up the eyes to collect the serum, the cerebral cortex, the hippocampus, and the spleen. The contents of5-HT, NA, CORT, ACTH in rats hippocampus and prefrontal cortex were determined by ELISA. The activities of SOD and GSH-Px were determined by Multifunctional microplate detection. Spleen tissue RNA was extracted, and the expression of genes of cytokines TNF-a, IL-1β, IL-4, TGF-β1were examined. The slice of hippocampus was made, and to HE and Nissl stained. Result showed that, L-theanine could significantly increase the contents of5-HT and NA, decrease the contents of ACTH and CORT in the hippocampus and prefrontal cortex of rats, increase the activities of SOD and GSH-Px in serum and prefrontal cortex, increased the expression of TNF-α, IL-1β,induced the expression of IL-4,TGF-β1. Observation of hippocampus slices found that L-theanine could meliorate the hippocampus pyramidal cells and plays a protective role on the nissl’s body.L-theanine could have the effect of prevention and treatment in CUMS rats. It main increase the contents of monoamine neurotransmitter, regulate the hormone secrete in the HPA axis, meanwhile eliminate the superabundance free radical, thereby plays the ameliorative effect through multichannel.