RESUMEN
【Objective】 To explore the effect of Lactobacillus rhamnosus on postpartum depression （PPD） and its potential mechanism. 【Methods】 The mouse model of PPD was established by using dexamethasone sodium phosphate during pregnancy. At the end of adaptive feeding， 50 pregnant female mice were randomly divided into low-dose group （group Ⅰ）， high-dose group （Group Ⅱ）， positive control group （Group Ⅲ）， model control group （Group IV）， and blank control group （Group Ⅴ）. The mice in Group Ⅰ and Group II were given Lactobacillus rhamnosus 1×107 and1×108CFU（kg·d）. The mice in Group Ⅲ were given 1.8 mg /（kg·d） paroxetine， and the mice in Groups IV and V were given the same amount of normal saline for 4 weeks. The 24-hour food consumption test， open field test and sugar water consumption test were used to detect the behavior of mice in each group. The concentrations of 5-hydroxytryptamine （5-HT）， norepinephrine （NE）， and dopamine （DA） were determined by RP-HPLC. The changes in Enterococcus faecalis， Bifidobacterium， Lactobacillus and Escherichia coli in the cecum of mice were detected by Real-time fluorescence quantitative PCR （RT-qPCR）. 【Results】 Before modeling， there were no significant differences in food intake， weight change rate， open field moving distance and speed， and percentage of sugar consumption among the groups （P>0.05）. After modeling， there was no significant difference in food intake or weight change rate among the five groups， but the open field moving distance， moving speed and percentage of sugar preference were significantly reduced （P<0.05）. After intervention with Lactobacillus rhamnosus， compared with Group Ⅳ， the depression-like behavior in Group Ⅰ and Group Ⅱ mice was improved； the weight change rate， open field moving distance and speed， percentage of sugar preference， and monoamine neurotransmitter concentration in Group I and Group Ⅱ were significantly increased compared with those in Group Ⅳ （P<0.05）， while Enterococcus faecalis， Escherichia coli and lactobacillus were significantly decreased （P<0.05）， and Bifidobacterium had an upward trend， but without significant difference. There was no significant change in food intake. 【Conclusion】 Lactobacillus rhamnosus can improve the depression-like behavior， affect monoamine neurotransmitters in mice， and regulate intestinal flora， which provides a new direction for studies on postpartum depression.