双歧杆菌对应激大鼠肠道菌群及促肾上腺皮质激素释放激素的影响

Influence of Bifidobacterium on the intestinal microflora and corticotropin-releasing factor in rats following chronic psychological stress

目的:探讨应激对大鼠肠道菌群及血清促肾上腺皮质激素释放激素(CRF)的影响及双歧杆菌对应激大鼠肠道功能的调节作用.方法:50只SD大鼠随机分为5组:正常对照组、压力实验组、双歧杆菌干预组、思密达干预组、双歧杆菌+思密达共同干预组.采用WAS(water avoidance stress)避水实验构建大鼠应激模型,以三糖为探针,衍生化毛细管气相色谱法测定大鼠尿液中三种糖的浓度,以三氯蔗糖/甘露醇(S/M)评价大鼠肠道通透性;取大鼠新鲜粪便,用选择性培养基平皿计数法检测大鼠粪便菌群中几种代表性菌种的数量取肠系膜淋巴结(MLN)培养后测定细菌移位率;用酶联免疫法测定大鼠血清中CRF和促肾上腺皮质激素(ACTH)的含量.结果:与正常对照组相比,压力实验组大鼠粪便中以大肠杆菌杆菌为主的条件致病菌数量增多(7.347±0.277vs7.078±0.229,P<0.05)24h尿液中甘露醇量升高(5.097%±0.453%vs4.718%±0.399%,P<0.05),MLN细菌移位率升高(40%vs10%,P<0.05);CRH(300.8ng/L±34.3ng/Lvs267.0ng/L±32.3ng/L,P<0.05)ACTH(6.79ng/L±0.651ng/Lvs5.68ng/L±0.799ng/L,P<0.05)水平升高.与压力实验组相比,双歧杆菌干预组大肠杆菌(7.044±0.281vs7.347±0.277,P<0.05)、类杆菌(9.075±0.393vs9.485±0.306,P<0.05)数量显著下降细菌移位率下降(10%vs40%,P<0.05);ACTH水平下降(5.92ng/L±0.477ng/Lvs6.79ng/L±0.651ng/L,P<0.05).结论:在慢性应激条件下,大鼠出现肠道菌群失调、肠道通透性升高、神经内分泌处于应激状态的现象,双歧杆菌能够缓解慢性应激所导致的上述现象.

AIM：To determine the influence of chronic psychological stress on intestinal microflora and corticotropin-releasing factor （CRF） and to investigate the protective effects of Bifidobacterium on intestinal function in rats. METHODS：Fifty female Sprague-Dawley rats were randomly and equally divided into five groups：normal group,stress group,Bifidobacterium group,Smecta group,and Bifidobacterium plus Smecta group. All these groups were subjected to either water avoidance stress （WAS） or normal condition for 2 h per day for 7 consecutive days. The in vivo intestinal permeability was evaluated by measuring urinary sucralose and other sugar probes including lactulose and mannitol using capillary column gas chromatography （CCGC）. Some representative genera of gut flora in rat feces were counted on selective culture medium plates. The mesenteric lymph nodes （MLN） were removed,homogenized and cultured to determine bacterial translocation. The contents of serum CRF and adrenocortico-trophic hormone （ACTH） were determined by enzyme-linked immunosorbent assay （ELISA）. RESULTS：Compared with the normal group,the number of Escherichia coli （7.347 ± 0.277 vs 7.078 ± 0.229,P 0.05）,the 24-h urinary concentration of mannitol （5.097% ± 0.453% vs 4.718% ± 0.399%,P 0.05）,the rate of bacterial translocation to the MLN （40% vs 10%,P 0.05）,and the levels of CRF （300.8 ng/L ± 34.3 ng/L vs 267.0 ng/L ± 32.3 ng/L,P 0.05） and ACTH （6.79 ng/L ± 0.651 ng/L vs 5.68 ng/L ± 0.799 ng/L,P 0.05） increased significantly in the stress group. In comparison with the stress group,the number of Escherichia coli （7.044 ± 0.281 vs 7.347 ± 0.277,P 0.05） and bacteroid （9.075 ± 0.393 vs 9.485 ± 0.306,P 0.05）; the rate of bacterial translocation to the MLN （10% vs 40%,P 0.05） and ACTH level （5.92 ng/L ± 0.477 ng/L vs 6.79 ng/L ± 0.651 ng/L,P 0.05） decreased significantly in the Bifidobacterium intervention group. CONCLUSION：The disturbance of intestinal microflora occurs and CRF increases significantly in rats suffered from chronic psychological stress. Bidifobacterium could alleviate the disturbance of gut microflora caused by chronic psychological stress and partly restore intestinal barrier function.