ABSTRACT
Objective:To study the effect of modified Xiao Chaihutang on the expressions of excitatory amino acid transporters（EAATs） and vesicle glutamate transporters（VGLUTs）in hippocampus of rats with chronic depression， in order to explore the anti-depressant mechanism of modified Xiao Chaihutang based on glutamate transport. Method:A total of 120 SD rats were randomly divided into normal group， model group， and low， middle and high-dose modified Xiaochaihutang groups （6.5， 13， 26 g·kg-1） and riluzole group， with 20 rats in each group．Except normal group， the depression model of rats was prepared through Chronic restraint stress（CRS）. The normal group and the model group were intragastrically （ig） given normal saline. The modified Xiao Chaihutang groups were intragastrically given corresponding herbal drugs （6.5， 13， 26 g·kg-1）， and the Riluzole group was given Riluzole 20 mg·kg-1 through intraoeritoneal injection for 21 days， once a day. Then the depressive behaviors of rats were observed by forced swimming test （FST） and tail suspension test （TST）. The level of glutamic acid （Glu） in rats hippocampus was determined by high performance liquid chromatography （HPLC）. The mRNA expressions of EAAT1， EAAT2 and EAAT3 in hippocampus were detected by Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR）method. Western blot was used to detect the protein expressions of EAAT1， EAAT2， EAAT3， VGLUT1 and VGLUT2 in rat hippocampus tissue. Nissl staining was used to observe the morphology of hippocampal neurons in rats. Immunohistochemical（IHC）S-P method were used to detect the location expressions of EAAT1， EAAT2 and NeuN proteins in rat hippocampal CA1 region tissue. Result:The immobility times in FST and TST were increased significantly（P<0.01）， the mRNA and protein expressions of EAAT1，EAAT2，EAAT3 were decreased significantly （P<0.01）， and as well as the expressions of VGLUT1 and NeuN were decreased significantly（P<0.01）， while the level of Glutamate and the expression of VGLUT2 were increased significantly（P<0.01） in model group， compared with normal group. Compared with model group，the immobility times in FST and TST were decreased significantly（P<0.05， P<0.01）， mRNA and protein expressions of EAAT1，EAAT2，EAAT3 were increased significantly（P<0.01）， and expressions of VGLUT1 and NeuN were increased significantly（P<0.01）. However， the level of Glutamate and the expression of VGLUT2 were decreased significantly（P<0.01）， and the damage of hippocampal neurons in rats was mild in middle and high-dose modified Xiao Chaihutang groups. Conclusion:Modified Xiao Chaihutang has an anti-depressive effect. Its mechanism may be related to its up-regulation of expressions of EAAT1， EAAT2， EAAT3 genes and VGLUT1 protein in the hippocampus of depression model rats.