中文摘要：

目的初步研究干酪乳杆菌对抑郁大鼠行为及肠道菌群的影响。方法 SD大鼠57只,经适应性喂养后按体质量随机分为正常对照组（A组）、模型对照组（B组）、阳性对照组（C组）、干酪乳杆菌低剂量组（D组）和干酪乳杆菌高剂量组（E组）。除A组外,其余各组大鼠均给予慢性不可预知温和刺激结合孤养建立抑郁模型。建模3周后通过灌胃给药的方式进行干预,D、E组大鼠分别给予干酪乳杆菌4×10～8和8×10～8 CFU/（kg·d）,C组大鼠给予1.8mg/（kg·d）帕罗西汀,A、B组大鼠给予等量的生理盐水,干预时间为4周。通过旷场实验、糖水消耗实验、24h食物消耗实验观察大鼠行为学变化,比较各组间行为学差异。行为学实验结束后,采用酶联免疫吸附试验（ELISA）法检测各组大鼠血浆中白细胞介素-6（IL-6）和肿瘤坏死因子-α（TNF-α）的水平;提取盲肠内容物DNA,采用实时荧光定量PCR（RT-PCR）方法检测粪肠球菌、双歧杆菌、乳酸杆菌和大肠杆菌的变化。结果干酪乳杆菌干预后D组和E组大鼠的抑郁样行为得到了改善,糖水偏爱百分比、旷场中的移动速度和距离均较B组显著增加（F=12.86～37.59,P〈0.01）,体质量变化率显著上升（F=3.39～5.61,P〈0.05）;24h食物消耗无显著变化;乳酸杆菌、大肠杆菌和粪肠球菌数量较B组显著下降（F=3.89～6.35,P〈0.05）,双歧杆菌数量有增加的趋势,但差异无显著性（P〉0.05）;血浆中IL-6和TNF-α的水平较B组显著下降（F=4.90、5.19,P〈0.05）。结论干酪乳杆菌能调节肠道微生态进而改善抑郁相关症状,这为抑郁症的研究和治疗提供了新的方向。

英文摘要：

Objective To investigate the effect of Lactobacillus casei on the behavior and intestinal flora of rats with depression. Methods After adaptive feeding,57 Sprague-Dawley rats were randomly divided into normal control group（group A）,model group（group B）,positive control group（group C）,low-dose Lactobacillus casei group（group D）,and high-dose Lactobacillus casei group（group E）according to their body weight.All rats except those in group A were given chronic unpredictable mild stimulation combined with social isolation to establish a model of depression.At 3weeks after model establishment,drugs were given by gavage for intervention.The rats in groups D and E were given Lactobacillus casei at a dose of 4×10～8 and 8×10～8 CFU/（kg·d）,respectively,those in group C was given paroxetine at a dose of 1.8mg/（kg·d）,and those in groups A and B were given normal saline at the same dose.The time of intervention was 4weeks.The open field test,sucrose consumption test,and 24-hour food consumption test were used to observe the behavioral changes,and the behaviors were compared between groups.After the behavioral tests were completed,ELISA was used to measure the plasma levels of interleukin-6（IL-6）and tumor necrosis factor-α（TNF-α）;the DNA of cecal contents was extracted and quantitative real-time PCR was used to measure the changes in Enterococcus faecalis,Bifidobacterium,Lactobacillus,and Escherichia coli. Results After the intervention with Lactobacillus casei,groups D and E showed improvements in depressive behaviors and had significant increases in the percentage of sucrose preference and moving velocity and distance in the open field compared with group B（F=12.86-37.59,P〈0.01）,as well as a significant increase in the change rate of body weight（F=3.39-5.61,P〈0.05）.There was no significant change in the 24-hour food consumption.Compared with group B,groups D and E had significant reductions in the numbers of Lactobacillus,Escherichia coli,and Enterococcus faecalis（F=3.