Abstract: Objective To investigate the effect of Flos Albiziae flavonoids(FAF) on behavior and brain-derived neurotrophic factor(BDNF)and apoptosis inducing factor(Bax) expression levels in chronic-stressed rats.Methods Totally 48 healthy male adult Sprague-Dawley rats of clean grade were diveded into 6 groups based on their preference to 1% sucrose drinking water and body weight.Normal control(NC),model control(MC),10.0 mg/kg of fluoxetine control(FC),and Flos Albizae fiavonoids(FAF) treatment groups of FAF1(20 mg/kg),FAF2(40 mg/kg) and FAF3(80 mg/kg).The treatments were administered with gavage once a day for 28 days.The chronic-stress model was developed with chronic unpredictable mild stress plus solitary dependents.The behavioral changes of the rats were observed.Contents of norepinephrine(NE) and serotonin(5-HT) were detected with high performance liquid chromatography.The apoptosis of hippocampus cells was measured with flow cytometry.BDNF and Bax expression in hippocampus of the rats were determined with immue western blot.Results Compared with the MC group,the cell apoptosis rate in hippocampus of FC group and high dose FAF group was significantly lower(P<0.01 for all).The conterts of 5-HT(611.0?115.8 ng/g,760.7?112.3) and NE(371.0?152.4 ng/g,430.0?153.1 ng/g) of FC and high dose FAF group were significantly higher(P<0.01 for all).The expression of BDNF decreased but that of Bax increased in hippocampus of MC rats,while the expression of BDNF increased and Bax decreased significantly for FAF rats(P<0.01 for all).Conclusion FAF antagonizes chronic stress-induced depression in rats,which may be related to increased brain 5-HT,NE content and expression of BDNF and reduced expression of Bax and hippocampal cell apoptosis.