痛泻要方对“肝气乘脾”泄泻小鼠肠黏膜及肠内容物消化酶活性的影响

目的探讨痛泻要方对"肝气乘脾"泄泻小鼠肠道酶活性的影响。方法采用"番泻叶-离心管束缚夹尾法"进行"肝气乘脾"泄泻造模,造模成功后以痛泻要方治疗,造模和治疗后分别分析小鼠肠道酶活性。结果造模后,模型组小鼠肠道内容物的淀粉酶活性显著降低(t=4.007,P=0.015),纤维素酶、蛋白酶、蔗糖酶活性下降不显著。模型组小鼠肠黏膜蛋白酶、淀粉酶、蔗糖酶活性显著下降(t_蛋=5.652,P=0.005;Z_淀=-1.964,P=0.050;t_蔗=4.737,P=0.009)。痛泻要方治疗后,中药干预组小鼠肠道内容物蛋白酶、纤维素酶、乳糖酶和蔗糖酶活性变化不显著;自然恢复组的淀粉酶活性显著高于正常组(t=-7.497,P=0.002)。中药干预组小鼠肠道前段黏膜蛋白酶、乳糖酶、淀粉酶、蔗糖酶活性恢复不显著;中药干预组小鼠肠道黏膜中段乳糖酶、蔗糖酶活性显著低于自然恢复组(t_乳=4.074,P=0.013;t_蔗=8.072,P0.001),而蛋白酶、淀粉酶及纤维素酶活性均高于自然恢复组;中药干预组小鼠肠道后段黏膜乳糖酶、蔗糖酶及淀粉酶活性显著高于正常组(t_乳=-7.962,P0.001;t_蔗=-15.921,P0.001;Z_淀=6.489,P=0.034),蛋白酶与纤维素酶活性均有所升高。结论 "肝气乘脾"泄泻肠道内容物及黏膜淀粉酶活性显著降低,痛泻要方对"肝气乘脾"泄泻小鼠肠黏膜乳糖酶、蔗糖酶及淀粉酶活性作用显著。     

三种乳杆菌对小鼠溃疡性结肠炎的缓解作用及机制CSCD

目的探讨3株乳杆菌(植物乳植杆菌、罗伊氏粘液乳杆菌和副干酪乳酪杆菌)对小鼠溃疡性结肠炎(ulcerative colitis,UC)的缓解作用及机制。方法采用葡聚糖硫酸钠(DSS)法构建C57BL/6J小鼠急性UC模型,并在造模前后均给予乳杆菌干预治疗;测量各组小鼠体质量、结肠长度;采用蛋白免疫印迹技术检测小鼠结肠上皮紧密连接蛋白表达水平;HE染色观察分析小鼠结肠组织病理变化;16S rDNA高通量测序分析小鼠肠道菌群组成情况;转录组测序分析小鼠结肠组织基因表达差异。结果与DSS模型组相比,植物乳植杆菌干预组(t=2.285,P=0.045)和副干酪乳酪杆菌干预组(t=2.360,P=0.040)小鼠体质量增加显著;植物乳植杆菌干预组(t=2.335,P=0.042)结肠长度显著增加;植物乳植杆菌干预组(ZO-1:t=4.975,P=0.003;Occludin:t=2.629,P=0.034)和罗伊氏粘液乳杆菌干预组(ZO-1:t=3.523,P=0.013;Occludin:t=2.525,P=0.040)紧密连接蛋白表达水平显著上调。乳杆菌干预组结肠黏膜组织病理损伤得以缓解,肠道菌群丰度及多样性降低得以改善。植物乳植杆菌干预组vs DSS模型组共有69个差异表达基因,KEGG pathway分析提示差异基因富集于免疫调节、内分泌与消化系统相关疾病等通路上。结论3株乳杆菌对UC小鼠展现出较好的缓解作用,其作用机制与修复肠道屏障、调节肠道微生物群结构和降低肠道炎症水平相关。     

大鼠慢性束缚应激后肠道病理及其菌群变化

基于慢性束缚应激法建立大鼠慢性应激模型,结合苏木精-伊红染色和肠道细菌基因间重复序列(enterobacterial repetitive intergenic consensus,ERIC)-PCR技术观察大鼠肠道组织病理及菌群变化规律。选取10只健康雄性sprague-dawley(SD)大鼠,随机分为对照组和模型组,每组5只。对照组正常饲养,模型组采用束缚筒每天束缚应激4 h,连续造模30 d,造模前后记录大鼠的体重并于造模后进行行为学评估,采用脱臼法处死并收集大鼠肠道组织及其内容物,包被切片后进行HE染色,肠道内容物初步分离后提取基因组DNA并采用ERIC-PCR检测菌群变化规律。结果显示,与对照组相比,应激模型组大鼠体重、穿越次数、直立次数、理毛次数均显著降低,强迫游泳不动时间显著延长、糖水偏爱显著降低;造模后大鼠肠道微绒毛结构破损严重,细胞核轻微固缩且深染,肠道菌群变化明显,出现了多个特征性变化条带。采用慢性束缚应激法并结合行为学评估成功建立了大鼠慢性应激模型,结合病理学检测和肠道菌群表达谱变化为基于慢性应激相关疾病的研究提供了重要参考,具有一定的应用价值。     

不同年龄段小鼠抑郁及焦虑样行为的比较

目的观察和比较不同年龄段实验小鼠的抑郁及焦虑样行为。方法将27只雄性C57BL/6小鼠按年龄分为青年组(3月龄,n=9)、中年组(10月龄,n=9)、老年组(18月龄,n=9),分别进行悬尾测试、强迫游泳测试、高架十字迷宫测试、开放旷场测试和糖水偏好测试,观察小鼠抑郁及焦虑样行为,并用液质联用(LC-MS/MS)法检测C57BL/6小鼠血清5-羟色胺含量。结果中年组小鼠比老年组小鼠的悬尾不动时间长(P0. 05);青年组、中年组、老年组小鼠强迫游泳不动时间显著递减,青年组小鼠游泳不动时间显著大于中年组小鼠(P0. 001)和老年组小鼠(P0. 001),中年组小鼠游泳不动时间显著大于老年组小鼠(P0. 01);中年组小鼠比老年组小鼠12小时糖水偏好率高(P0. 05),青年组小鼠比老年组小鼠12、36、48、60小时糖水偏好率高(P0. 05);老年组小鼠比中年组和青年组小鼠开臂时间长(P0. 05),青年组小鼠比中年组小鼠探头次数多(P0. 01);青年组小鼠比老年组小鼠在旷场中的移动总距离长(P0. 05);老年组、中年组、青年组小鼠血清5-HT含量呈递减趋势,青年组小鼠血清5-HT显著低于中年组(P0. 05)和老年组(P0. 01)。结论整体而言,同一刺激下,小鼠的年龄越小,越易表现出抑郁及焦虑样行为,血清中5-HT水平越低。     

ERIC-PCR指纹图谱技术分析糖尿病小鼠肠道细菌群落变化

目的通过比较1型糖尿病模型组和空白对照组雄性小鼠肠道菌群结构的变化,探索糖尿病造模与肠道菌群的关系。方法收集造模2周后空白对照组(n=5)、STZ造模成功组(n=5)和造模不成功组(n=3)ICR小鼠的新鲜粪便样品,提取粪便样品的总DNA,ERIC-PCR扩增形成DNA指纹图谱,借助多变量统计分析方法研究各组样品肠道菌群结构上的异同。结果ERIC-PCR指纹图谱结合偏最小二乘法(PLS-DA)分析表明造模成功组和造模不成功组小鼠的肠道菌群结构显著区别于空白对照组,而造模不成功组小鼠的肠道菌群结构与造模成功组仍有一定的区别。结论STZ诱导的1型糖尿病会造成小鼠的肠道菌群结构的变化,而部分小鼠造模失败可能与这些小鼠的肠道菌群结构有关。     

栀子粗提物对抑郁模型小鼠行为学及海马神经发生的影响

目的观察栀子粗提物对慢性轻度应激模型小鼠行为学及海马神经发生的影响。方法采用10种不同应激源实施对小鼠连续10周刺激,从第3周开始口服给予栀子粗提物3个剂量治疗8周后,测定各组小鼠行为学改变,并采用NeuN和BrdU免疫组化观察海马区神经细胞的增殖情况。结果栀子粗提物高剂量组蔗糖饮水量明显增加（P〈0.05）,强迫游泳不动时间明显缩短（P〈0.05）;NeuN阳性表达升高（P〈0.01）,BrdU阳性细胞的面数密度亦显著增加（P〈0.05）。结论栀子粗提物对抑郁模型小鼠行为有明显改善作用,并能显著促进海马区神经元发生,提示栀子粗提物具有良好的抗抑郁作用。     

低聚果糖对溃疡性结肠炎模型小鼠肠黏膜屏障影响的研究

目的探讨低聚果糖对溃疡性结肠炎(UC)模型小鼠肠黏膜屏障的调节作用及可能机制。方法小鼠随机分成3组:正常对照(NC)组、模型(MD)组和低聚果糖(FOS)组,采用葡聚糖硫酸钠制作UC小鼠模型。造模7d同时给予干预治疗,停用造模药物并后续治疗7d。采用细菌定量测定法检测肠道菌群,放射免疫法检测肠黏膜sIgA,ELISA法检测小鼠肠黏膜IL-10、TNF-α和IL-6水平。结果模型组小鼠存在肠道菌群失调(t=2.088,2.036,2.203,2.109,P0.05),其TNF-α、IL-6水平高于正常对照组(t=1.734,1.801,P0.05),肠黏膜sIgA、IL-10低于正常对照组(t=1.820,1.806,P0.05);低聚果糖组肠道菌群失调状况较模型组有所改善,其TNF-α、IL-6水平低于正常对照组(t=1.980,1.816,1.936,1.920,1.969,1.893,P0.05),肠黏膜sIgA、IL-10高于正常对照组(t=1.801,1.796,P0.05)。结论低聚果糖可改善溃疡性结肠炎模型小鼠肠道菌群屏障功能,可以提高肠黏膜sIgA和抗炎细胞因子IL-10的水平并降低致炎细胞因子TNF-α和IL-6的水平,通过调节肠道过度的免疫反应,使免疫屏障功能得到一定恢复。     

番泻叶造模对小鼠肠道微生物及 酶活性的影响

目的探讨灌胃番泻叶脾虚腹泻造模方法对小鼠肠道微生物及酶活性的影响。方法采用灌胃番泻叶水煎液进行小鼠脾虚造模。12只小鼠随机分为模型组和正常组,模型组灌胃番泻叶水煎液,正常组灌胃等量无菌水,期间观察小鼠的一般情况变化。灌胃7d后称重、无菌采集肠道内容物,分析肠道菌群及酶活性。结果与正常组相比,模型组小鼠肠道内容物的淀粉酶活性升高极显著(t=-53.0671,P=0.0000),纤维素酶活性和木聚糖酶活性下降显著(t=23.1230,P=0.0000;t=12.3900,P=0.0410),而蛋白酶活性变化不明显(t=1.3120,P=0.0521);模型组小鼠细菌总数显著减少(t=73.1601,P=0.0000),而大肠埃希菌、乳杆菌、双歧杆菌和真菌总数变化均不明显(t=2.3580,P=0.1432;t=2.2089,P=0.1127;t=2.2813,P=0.1037;t=9.3210,P=0.0510)。结论脾虚造模会使细菌总数减少,纤维素酶和木聚糖酶活性下降,淀粉酶活性升高。     

微清蛋白中间神经元在氯胺酮抗抑郁中的作用

目的:观察微清蛋白(PV)中间神经元在氯胺酮抗抑郁中的作用。方法:32只Wistar雄性大鼠随机均分为4组(n=8),包括生理盐水组(S组)、氯胺酮组(K组)、夹竹桃麻素预处理+生理盐水组(AS组)、夹竹桃麻素预处理+氯胺酮组(AK组)。夹竹桃麻素预处理组将药物溶于大鼠饮水中,共喂养1周,于第8 d制备模型。大鼠强迫游泳15 min制备急性应激抑郁模型,24 h后给大鼠分别腹腔注射1 mL生理盐水或氯胺酮10 mg/kg,给药后0.5 h行敞箱实验记录大鼠水平运动及垂直运动得分,行强迫游泳6 min记录后5 min内不动时间。行为学测试结束后,取大鼠前额皮层,Western印迹检测PV中间神经元中PV及谷氨酸脱羧酶67(GAD67)的表达。结果:与S组相比,K组大鼠强迫游泳不动时间减少,PV及GAD67的表达下降(P0.05),AS组则无显著变化(P0.05);与K组相比,AK组大鼠强迫游泳不动时间增加,PV及GAD67的表达增加(P0.05)。生理盐水、氯胺酮、夹竹桃麻素均未显著影响大鼠自主活动(P0.05)。结论:氯胺酮通过下调大鼠前额皮层PV中间神经元功能发挥快速有效的抗抑郁作用。     

肠道菌群及代谢与载脂蛋白E在动脉粥样硬化中的相互作用

目的明确肠道菌群及代谢与载脂蛋白在动脉粥样硬化中的相互作用。方法 C57BL/6J小鼠作为对照组(n=5),载脂蛋白E基因敲除(apolipoprotein E-deficient mice,ApoE~(-/-))小鼠作为动脉粥样硬化模型组(n=8),均为6周龄雄性。两组小鼠均给予高脂饮食,饲养12周后麻醉、摘眼球取血,采用全自动生化分析仪检测血脂,高效液相色谱串联质谱法测定血浆氧化三甲胺(Trimethylamine N-oxid,TMAO)的含量,留取粪便用于肠道菌群16S rRNA V3-V4区域的测序进行菌群鉴定,油红"O"染色主动脉根部确定动脉粥样硬化斑块面积。结果血清学指标:ApoE~(-/-)小鼠较对照组血浆中TMAO(t=-2.87,P0.05)、LDL(t=-11.76,P0.05)、TG(t=-3.56,P0.01)、TC(t=-12.38,P0.01)含量及动脉粥样硬化斑块面积(t=-11.94,P0.01)显著增加,HDL含量降低(t=3.63,P0.01)。肠道菌群测序:两组小鼠随着动脉斑块面积的增加,肠道微生物的丰富度、物种组成及功能预测分析等差异均有统计学意义,还发现ApoE~(-/-)小鼠能够生成TMAO的肠道菌群包括Anaeroplasma、Anaeroplasmatales、Anaeroplasmataceae、Proteus、Paraprevotella和Paraprevotellaceae,而对照组生成TMAO的菌群只有1类,为Anaerotruncus。结论 C57BL/6J小鼠与ApoE~(-/-)小鼠肠道微生物群落的组成、功能及其代谢产物TMAO的血浆含量各不相同,提示ApoE基因缺乏的宿主除导致脂质代谢紊乱外,在动脉粥样硬化形成过程中一定程度上影响着肠道菌群的代谢。     

慢性避水应激大鼠肠道菌群和ROS的变化

目的探讨应激诱导的内脏高敏感大鼠中肠道菌群及活性氧簇(ROS)的变化。方法建立慢性避水应激大鼠模型,分为应激组和对照组(每组6只)。腹部回撤反射(abdominal withdrawal reflex,AWR)方法评估大鼠内脏敏感性。免疫荧光和ELISA方法检测肠道和血液中ROS的表达水平。粪便进行16S rDNA菌群测序分析。细胞培养方法检测大鼠结肠黏膜菌群代谢产物对巨噬细胞ROS生成的影响。结果慢性避水应激能诱导大鼠内脏敏感性增高。与对照组相比,应激组大鼠肠道和血液中ROS表达均增加,不同水平上肠道菌群都有所变化,生物多样性下降。Spirochaetia菌的丰富度与ROS的表达呈负相关。应激组大鼠结肠黏膜菌群诱导巨噬细胞产生更高水平的ROS。结论应激诱导大鼠肠道菌群发生紊乱引起ROS生成增加并存在相关性。     

粪菌移植对小鼠实验性结肠炎TLR4信号通路及肠黏膜屏障的影响

目的探讨粪菌移植(FMT)对溃疡性结肠炎(UC)小鼠肠黏膜屏障的影响及可能机制。方法小鼠饮用2.0%葡聚糖硫酸钠(DSS)溶液构建小鼠UC模型;50只成年雄性C57BL/6J小鼠,随机留取10只取粪便(这10只不参与后续的实验),其余40只称重、编号,随机分为空白对照组(Con组)、DSS模型对照组(Model组)、美沙拉嗪组(Model+5-ASA组)和粪菌液组(Model+FMT组),每组10只,Con组和Model组均给予0.9%NaCl溶液灌肠,给药组分别给予美沙拉嗪、粪便滤液灌肠;评估疾病活动指数(DAI)、各组结肠组织病理情况,用透射电镜检测各组小鼠的结肠黏膜上皮细胞结构的变化情况,ELISA检测各组血清内毒素、炎症因子TNF-α水平变化,免疫组化法检测结肠组织Toll样受体4(TLR4)及核因子-κB(NF-κB)的表达变化,Western blot检测各组ZO-1蛋白表达。结果与Model组相比,粪菌移植明显改善小鼠的DAI指数和结肠组织的病理损伤,结肠上皮细胞间隙增宽程度减轻,腺上皮细胞间连接较紧密,结肠黏膜上皮细胞微绒毛完整,排列整齐,内毒素、TNF-α的含量明显下降,TLR4及NF-κB在结肠组织的表达明显下降,ZO-1蛋白表达明显升高,促进结肠黏膜屏障的修复,差异具有统计学意义(t=7.9543,P<0.0001;t=3.7641,P=0.0010;t=4.5899,P=0.0020;t=13.2886,P<0.0001;t=4.9750,P=0.0010;t=6.9388,P<0.0001;t=8.3744,P<0.0001)。结论FMT可减少内毒素及炎症因子的产生,改善结肠炎症,TLR4-NF-κB信号通路可能是FMT修复结肠黏膜屏障功能的机制之一。     

Abnormal Hippocampal BDNF and miR-16 Expression Is Associated with Depression-Like Behaviors Induced by Stress during Early Life

Some environmental stressors lead to the onset of depression via inhibiting hippocampal BDNF expression, but other environmental stressors-induced depression exhibits no change in BDNF expression. The underlying mechanisms behind the divergence remain unknown. In this study, depression-like behaviors were induced in rats by maternal deprivation (MD) and chronic unpredictable stress (CUPS). Depression-like behaviors were tested by open field test, forced swimming test, and sucrose consumption test. BDNF and miR-16 expressions in the hippocampus were examined by real-time PCR. MD and CUPS rats crawled less distance, exhibited decreased vertical activity, and produced more fecal pellets than control rats in the open field test. However, MD rats crawled less distance and produced significantly less fecal pellets than CUPS rats. In the forced swimming and sucrose consumption tests, CUPS and MD rats exhibited longer floating time and consumed less sucrose than control rats, but MD rats exhibited shorter floating time and consumed less sucrose than CUPS rats. MD but not CUPS rats showed lower BDNF mRNA and higher miR-16 expression than control rats. In MD rats, BDNF mRNA expression negatively correlated with the expression of miR-16. BDNF expression positively correlated with the total distance rats crawled and vertical activity in the open field test while miR-16 expression negatively correlated the two behaviors. BDNF positively correlated with sucrose preference rate while miR-16 negatively correlated with sucrose preference rate of the sucrose consumption test. Our study suggests that MD and CUPS induced different depression-like behaviors in rats. Depression induced by MD but not CUPS was significantly associated with upregulation of miR-16 and possibly subsequent downregulation of BDNF in hippocampus.     

Antidepressant-like Effect of Bacopaside I in Mice Exposed to Chronic Unpredictable Mild Stress by Modulating the Hypothalamic–Pituitary–Adrenal Axis Function and Activating BDNF Signaling Pathway

Preliminary studies conducted in our laboratory have confirmed that Bacopaside I (BS-I), a saponin compound isolated from Bacopa monnieri, displayed antidepressant-like activity in the mouse behavioral despair model. The present investigation aimed to verify the antidepressant-like action of BS-I using a mouse model of behavioral deficits induced by chronic unpredictable mild stress (CUMS) and further probe its underlying mechanism of action. Mice were exposed to CUMS for a period of 5 consecutive weeks to induce depression-like behavior. Then, oral gavage administrations with vehicle (model group), fluoxetine (12 mg/kg, positive group) or BS-I (5, 15, 45 mg/kg, treated group) once daily were started during the last two weeks of CUMS procedure. The results showed that BS-I significantly ameliorated CUMS-induced depression-like behaviors in mice, as characterized by an elevated sucrose consumption in the sucrose preference test and reduced immobility time without affecting spontaneous locomotor activity in the forced swimming test, tail suspension test and open field test. It was also found that BS-I treatment reversed the increased level of plasma corticosterone and decreased mRNA and protein expressions of glucocorticoid receptor induced by CUMS exposure, indicating that hypothalamic–pituitary–adrenal (HPA) axis hyperactivity of CUMS-exposed mice was restored by BS-I treatment. Furthermore, chronic administration of BS-I elevated expression levels of brain-derived neurotrophic factor (BDNF) (mRNA and protein) and activated the phosphorylation of extracellular signal-regulated kinase and cAMP response element-binding protein in the hippocampus and prefrontal cortex in mice subjected to CUMS procedure. Taken together, these results indicated that BS-I exhibited an obvious antidepressant-like effect in mouse model of CUMS-induced depression that was mediated, at least in part, by modulating HPA hyperactivity and activating BDNF signaling pathway.     

海马齿状回神经再生对WKY大鼠抑郁样行为的影响*

目的:观察海马齿状回(DG)神经再生对成年Wistar Kyoto(WKY)大鼠抑郁样行为的影响。方法:实验共分三个组(n = 10):①正常对照(Wistar)组:选取 9 周龄Wistar大鼠,给予生理盐水 3 周(10 mg/kg, 灌胃);②抑郁模型(WKY)组:选取同龄WKY大鼠并经行为学测定后筛选出抑郁大鼠作为抑郁模型组,给予生理盐水 3 周(10 mg/kg, 灌胃);③阳性对照(AMI+WKY)组:选取同龄WKY抑郁大鼠,给予阿米替林(AMI) 3 周(10 mg/kg, 灌胃)。选用免疫荧光染色细胞增殖标记物Ki67、未成熟神经元标志物DCX检测大鼠的海马神经再生水平;应用糖水偏好实验(SPT)、旷场实验(OFT)和强迫游泳实验(FST)检测各组大鼠的抑郁样行为学变化。结果:①WKY抑郁大鼠海马DG区细胞增殖标志物Ki67⁺细胞数和未成熟神经元标志物DCX⁺细胞数较Wistar大鼠分别降低了 33.0%(P＜0.01)和39.2%(P＜0.01);阿米替林给药后使抑郁大鼠海马DG区Ki67⁺细胞数和DCX⁺细胞数分别增加了43.8%(P＜0.01)和46.7%(P＜0.01)。②与Wistar大鼠相比,WKY抑郁大鼠糖水偏好程度明显降低(P＜ 0.01),旷场实验中运动总距离显著缩短(P＜0.01)和中心停留时间显著减少(P＜0.01),强迫游泳实验中不动时间明显延长(P＜ 0.01);阿米替林治疗可显著改善WKY大鼠的上述抑郁样行为。结论:①成年WKY抑郁大鼠的海马神经干细胞的增殖和分化能力较正常对照组显著降低,提示成年WKY抑郁大鼠的神经再生受损;②改善海马受损的神经再生可以部分逆转成年WKY大鼠的抑郁样行为。     

被动游泳运动对小鼠抑郁样行为及其肠道菌群组成的影响

被动游泳运动可诱发小鼠抑郁样行为,游泳环境的改变已成为抑郁样行为严重程度影响因素之一。观察不同水质、水温及持续时间对被动游泳小鼠抑郁样行为的影响,并初步探讨肠道菌群组成与抑郁样行为的关系。通过不同条件下的被动游泳运动建立抑郁样行为小鼠模型。采用糖水偏好实验及强迫游泳实验评价其行为学变化;采用16S rDNA高通量测序技术及实时荧光定量PCR技术对小鼠肠道菌群进行分子生态学分析。被动游泳16周后,各模型组小鼠体质量及糖水偏爱度均较正常对照组降低,而不动时间则有所延长。其中,室温海水游泳15 min小鼠体质量及糖水偏爱度降低程度最大,不动时间最长,与正常对照组比较,均具有显著性差异（P<0.05）。各模型组小鼠肠道菌群Chao指数、Shannon指数及PCoA分析均较正常对照组具有显著性差异（P<0.05）,其从门水平到属水平的丰度也发生不同程度改变。其中,室温海水游泳15 min小鼠肠道菌群组成变化程度最大,并发生拟杆菌属、普氏菌属等多个菌属的富集以及乳杆菌属丰度的减少,实时荧光定量PCR实验也得到了较为一致的结果（P<0.05）。以上结果表明,被动游泳运动可导致小鼠抑郁样行为的发生,其肠道菌群组成也发生明显改变;同时,菌群组成的改变会随着抑郁样行为的严重程度而有所变化。     

TNFα mediates stress-induced depression by upregulating indoleamine 2,3-dioxygenase in a mouse model of unpredictable chronic mild stress

Depression is often preceded by exposure to stressful life events. Chronic stress causes perturbations in the immune system, and up-regulates production of proinflammatory cytokines, which has been proposed to be associated with the pathogenesis of clinical depression. However, the potential mechanisms by which stress-induced proinflammatory cytokines lead to the development of depression are not well understood. Here, we sought to screen the main proinflammatory cytokines and the potential mechanisms linking inflammation to depression-like behavior during unpredictable, chronic, mild stress (UCMS), in vivo. Mice were allocated into four groups in each separate experiment: saline-control, saline-UCMS, drug-control and drug-UCMS. Development of depression-like behavior was reflected as a reduction in sucrose preference, and increased immobility in both the forced swim and tail suspension tests. The following drugs were administered intraperitoneally: the pan-anti-inflammatory tetracycline derivative, minocycline (30 mg/kg, daily), the tumor necrosis factor (TNF)α monoclonal antibody, infliximab (10 mg/kg, twice weekly), and the indoleamine 2, 3-dioxygenase (IDO) inhibitor, 1-methyltryptophan (1-MT, 10 mg/mouse, daily). Plasma TNFα, IL-1β and IL-18 increased significantly after the four-week UCMS exposure. Pretreatment of mice with minocycline completely blocked any upregulation. Concurrent with development of depression-like behaviors, the concentration of TNFα in plasma and the cerebral cortex increased remarkably. The tryptophan-degrading enzyme IDO was up-regulated in the cortex following UCMS exposure. Treatment of mice with minocycline, infliximab or 1-MT prevented the development of depression-like behaviors. Furthermore, blockade of TNFα inhibited expression of IDO and protected cortical neurons from UCMS-induced damage. These results suggest that TNFα plays a critical role in mediating UCMS-induced depression through up-regulation of IDO and subsequent damage of cortical neurons.     

Mice Lacking NMDA Receptors in Parvalbumin Neurons Display Normal Depression-Related Behavior and Response to Antidepressant Action of NMDAR Antagonists

The underlying circuit imbalance in major depression remains unknown and current therapies remain inadequate for a large group of patients. Discovery of the rapid antidepressant effects of ketamine - an NMDA receptor (NMDAR) antagonist – has linked the glutamatergic system to depression. Interestingly, dysfunction in the inhibitory GABAergic system has also been proposed to underlie depression and deficits linked to GABAergic neurons have been found with human imaging and in post-mortem material from depressed patients. Parvalbumin-expressing (PV) GABAergic interneurons regulate local circuit function through perisomatic inhibition and their activity is NMDAR-dependent, providing a possible link between NMDAR and the inhibitory system in the antidepressant effect of ketamine. We have therefore investigated the role of the NMDAR-dependent activity of PV interneurons for the development of depression-like behavior as well as for the response to rapid antidepressant effects of NMDAR antagonists. We used mutant mice lacking NMDA neurotransmission specifically in PV neurons (PV-Cre+/NR1f/f) and analyzed depression-like behavior and anhedonia. To study the acute and sustained effects of a single NMDAR antagonist administration, we established a behavioral paradigm of repeated exposure to forced swimming test (FST). We did not observe altered behavioral responses in the repeated FST or in a sucrose preference test in mutant mice. In addition, the behavioral response to administration of NMDAR antagonists was not significantly altered in mutant PV-Cre+/NR1f/f mice. Our results show that NMDA-dependent neurotransmission in PV neurons is not necessary to regulate depression-like behaviors, and in addition that NMDARs on PV neurons are not a direct target for the NMDAR-induced antidepressant effects of ketamine and MK801.     

Degradation and fermentation of fructo-oligosaccharides by oral streptococci

Fructo-oligosaccharides (FOS) are claimed to have a positive effect on the intestinal flora. They are being used in functional foods in Japan and Europe. This group have tested the degradation of two commercial FOS preparations by oral streptococci in order to predict the cariogenicity of these products. Both preparations could be fermented to some extent by the species of oral streptococci tested.
The enzymes necessary for the degradation of FOS were inducible. Each strain showed a specific degradation pattern. All strains, particularly Streptococcus mutans rapidly produced acid, mainly lactic acid. Streptococcus mitis also produced high concentrations of acetic acid. Plaque formation by Strep. mutans was similar to the sucrose control. It is concluded that FOS are cariogenic to a similar extent as sucrose.