The Effects Of L-theanine On Behavior And Neurotransmitter Of Depression Model Rats

Objective:To investigate the changes of the depression model rats’ behavior and the monoamines and glutamate neurotransmitter in prefrontal cortex (PFC), nucleus accumbens (NAC), striatum (ST), amygdala (AM) and hippocampus (HIP), and to explore the antidepressive effect and the possible mechanisms related to the tea extract theanine and the antidepressant fluoxetine.Method:1. Animal model:The Sprague-Dawley male rats were randomly divided into four groups including normal control group, model control group, fluoxetine group and theanine group. To establish chronic depression model rats by the chronic unpredictable mild stress (CUMS) and separation after21days.2. Behavioral index:recorded the weight changes, the total movement distance in the open-field test, the sucrose preference values in the sucrose consumption test, and the immobility time of the force swimming test during the experiments.to discuss the effects of theanine and fluoxetine.3. Neurotransmitter index:recorded the concentration of the monoamine neurotransmitters (NE,5-HT, HIP)its metabolites and the glutamate (GLU) and glutamine (GLN) in the four depression model group rat, by using coularray HPLC., to discuss the possible mechanisms of Theanine and fluoxetine.Results:1. Compared with the control group, the body weight, the total movement distance, the volume and percentage of the sucrose consumption test, were significantly decreased.the immobility time in FST was growth remarkably in the model group P<0.05).Compared with the model group, the body weight, the total movement distance, the volume and percentage of the sucrose consumption test, were significantly enhanced.the immobility time in FST was decreased remarkably, suggested interest improved, pleasure enhanced, the hopeless and helpless reduced in the theanine group and fluoxetine group(P<0.05).2. Compared with the control group, monoamine neurotransmitter NE, DA and5-HT and some of its metabolites in the brain region PFC, NAC, ST (except NE), AM (except NE\5-HT) and HIP decreased significantly, GLU and GLN both increased significantly in the model group (P<0.05).Compared with the model group, monoamine neurotransmitter NE, DA and5-HT and some of its metabolites in the brain region PFC, NAC, ST (except NE), AM (except NE\5-HT), HIP (except NE) increased significantly, GLU and GLN both decreased significantly in the fluoxetine group(P<0.05).Compared with the model group, monoamine neurotransmitter NE, DA and5-HT and some of its metabolites in the brain region PFC、NAC、 ST (except NE)、AM(except5-HT)、increased significantly, GLU and GLN both decreased significantly in the theanine group(P<0.05).Conclusion:1. The indexes of depressive behavior of model group is reduced, The changes of NE,5-HT, DA and GLU in PFC,NAC,ST,AM, HIP, which is related to the indexes of behaviors, and antidepressant fluoxetine treatment can improve them, which means the chronic unpredictable mild stress (CUMS) and separation is an effective method to establish depression animal model, and the changes of the monoamines and glutamate neurotransmitter in different brain regions that may be one of the pathogenesis mechanisms of depression.2. Theanine and fluoxetine can effectively improve the depressive behavior of the depression model rats, increase the content of monoamine neurotrans-mitter NE,5-HT, DA and its metabolites, and reduce the content of GLU and its precursor GLN,in the PFC,NAC, AM, ST and HIP brain regions. suggested that the antidepressant effect and possible mechanism of theanine may be related to the neurotransmitters. Compared with fluoxetine, the antidepressant mechanism of theanine is more extensive, specificity is more weak than fluoxetine.