OBJECTIVE:To provide basis and thinking for the development of medicines for treating depression. METHODS:Rats with adaptive feeding for 7 d were randomly divided into normal group,depression group and treatment group(citalopram hy-drobromide 1 mg/kg),8 in each group. Rats in depression group and treatment groups randomly received once low-density stimula-tion in a day [catching tail stimulation(1 min),frequent flashing stimulation(120 times/min,12 h),noise stimulation(4 h),ice water swimming stimulation(1 h),hot water stimulation(45 ℃,1 h),electric shocking foot(10 Hz,1 mA,each time interval of 100 ms,100 times),no food and no water(24 h)] for 21 d to reduce stress depression model. Body mass of rats in 0,7 d of adaptive feeding and 7,14,21 d of stress were respectively weighed,and horizontal activity and vertical activity frequencies in open field test were detected. After stress,rats were intragastrically administrated related medicines for 30 d,then 5-hydroxytrypta-mine (5-HT) and tryptophan hydroxylase (TPH) expressions in brain,liver,kidney tissues were determined. RESULTS:Com-pared with normal group,the increasing trend of body mass in depression group and treatment group slowed down from the 14 d of stress(P<0.05). The horizontal activity frequencies in depression group and treatment group in 14,21 d of stress slowed more ob-viously than the previous time point (P<0.05 or P<0.01);vertical activity frequencies in 21 d of stress slowed more obviously than the previous time point (P<0.05 or P<0.01). After 30 d of administration,horizontal activity and vertical activity frequen-cies in treatment group were increased more obviously than the previous time point (P<0.01). Compared with depression group,brain tissue of rats,indicating that TPH can be used as a target for depression treatment.