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。     

头端延髓腹外侧区注射5-羟色胺对应激性高血粘度及血压升高的影响

实验用Wistar大鼠62只,采用束缚加悬吊的方法引起应激性高血粘度和血压升高。结果观察到,清醒大鼠束缚加悬吊二天可引起应激性高血粘度和血压升高。第四脑室内注射5-羟色胺(5-HT25μg/10μl)或在双侧延髓腹外侧区头端(rVLM)微量注射5-HT(4μg/0.5μl/每侧)均可抑制应激性高血粘度和血压升高,若预先在双侧rVLM微量注射5-HT受体阻断剂肉桂硫胺(4μg/0.5μl/每侧)后再在第四脑室或延髓腹外侧区内注入上述同剂量的5-MT,则5-HT降低应激性高血粘度和血压升高的作用消失。看来上述5-HT的作用是通过rVLM内5-HT受体的激活来实现的。     

第四脑室注射吗啡对应激性高血粘度与血压升高的影响

实验用Wistar大鼠99只,雄性250g左右,随机分三组:对照组、悬吊加束缚组、悬吊一束缚加电针组。结果:(1)清醒大鼠束缚加悬吊可引起应激性高血粘度和血压升高,切断双侧颈迷走神经后上述现象仍存在。静脉注射心得安(0.3mg/ml)或酚妥拉明(0.3 mg/ml)对正常大鼠血压、血粘度影响不大,但对应激性血压升高均有抑制作用。静脉注射心得安还可降低应激性高血粘度。(2)电针大鼠右后肢对应激性高血粘度和血压升高有抑制作用。(3)第四脑室内注射吗啡(10μg/10 μl)15或30min后可降低应激性高血粘度和血压升高,注入等量生理盐水无变化。若在第四脑室注射纳洛酮 (10μg/10μl)则可部分阻断电针右后肢对悬吊-束缚诱发的高血粘度和血压升高的抑制作用。结果提示:悬吊-束缚大鼠可能兴奋交感神经传出系统经激活β受体诱发应激性高血粘度阻断α或β受体可降低应激性血压升高。脑内阿片肽可抑制应激性高血粘度和血压升高,脑内河片肽受体的激活可参与电针后肢对应激性高血粘度和血压升高的抑制作用。     

大鼠肥胖抑郁模型建立及肠道菌群多样性的性别差异研究

目的 肥胖抑郁大鼠模型建立并对比研究肠道菌群多样性的变化。方法 采用高脂饲料喂养和CUMS经典造抑郁方法建立肥胖抑郁模型。将SD大鼠随机分为正常组(C组)、单纯肥胖组(F组)、单纯抑郁组(Y组)和肥胖抑郁组(FY组),整个造模持续5个月，通过糖水偏好实验、旷场实验和强迫游泳实验来评估大鼠抑郁样行为，检测模型鼠血清雌激素水平和血脂4项，并采集各组大鼠粪便样品，通过16S rDNA高通量测序法和生物信息分析软件分析测序结果，比较各组大鼠肠道菌群多样性的变化。结果 高脂饮食和CUMS方法成功制作肥胖抑郁鼠模型，肥胖和肥胖抑郁雌性大鼠雌激素水平明显升高，而雄性各组间雌激素水平无显著性差异。雌雄鼠的FY组肠道菌群α多样性具有显著差别，拟杆菌门和厚壁菌门B/F比值下降，且雄鼠肥胖抑郁B/F值只有雌鼠的一半左右。在属水平，研究结果表明雌雄鼠FY组和F组肠道菌群中Blautia等8个菌群变化一致，但是雌性与雄性在拟杆菌属等各有少量菌群的变化不一致。雌雄肥胖抑郁模型中，肠道菌群革兰氏阳性菌和阴性菌的组成出现差异，G⁺的构成，雌性和雄性均由由厚壁菌门和放线菌门构成，但构成比例不一样。...     

小檗碱对肠易激综合征大鼠肠道菌群的影响

目的通过口服小檗碱(Berberine,BBR)治疗大鼠肠易激综合征(IBS),初步研究小檗碱对IBS大鼠肠道菌群的影响。方法用避水应激试验制作大鼠IBS模型,分别给予模型大鼠小剂量(25mg/kg)小檗碱、大剂量(100mg/kg)小檗碱和利福昔明干预治疗10d,检测大鼠肠道菌群丰度、生物多样性及菌群结构组成的变化。结果避水应激试验造模后模型组大鼠排便次数增多、腹外斜肌EMG明显升高,肠道可见微炎症表现。小檗碱干预后,IBS大鼠排便增多情况、内脏高敏感性和肠道微炎症情况均显著改善,其中大剂量小檗碱组优于小剂量组。经小檗碱干预后,大鼠肠道菌群多样性显著降低,大剂量小檗碱抑菌作用强于小剂量小檗碱。大剂量小檗碱可显著提高IBS大鼠肠道乳杆菌科细菌的比例,同时降低肠杆菌科细菌的比例。结论小檗碱可以显著降低IBS大鼠内脏高敏感性,改善肠道微炎症,减少IBS大鼠排便增多症状。小檗碱可以调节肠道菌群丰度和多样性,且剂量越大,抑菌作用越明显。肠道乳杆菌科细菌在小檗碱治疗肠易激综合征的过程中可能起一定作用。     

常见SPF级小鼠和大鼠肠道菌群多样性研究

目的研究常见SPF级小鼠和大鼠的肠道菌群多样性。方法分别采集广东地区三家实验动物生产单位的C57BL/6、ICR、BALB/c小鼠和Wistar、SD大鼠的盲肠内容物样品,用细菌16S rDNA通用引物扩增V4-V5区域,采用Illumina Miseq 2×300 bp测序平台进行测序,使用生物信息学方法进行微生物群落分析、Alpha多样性分析与Beta多样性分析。结果对序列去杂优化后OTU聚类分析,稀释性曲线说明本次测序的数据量合理;实验小鼠和大鼠肠道菌群共分成八个门,其中拟杆菌门(Bacteroidetes)、厚壁菌门(Firmicutes)占据主要地位,属水平上主要是拟杆菌属(Bacteroides)、Hungatella、副杆状菌属(Parabacteroides)、乳酸杆菌属(Lactobacillus)等;样品间差异性分析显示相同设施来源动物的菌群组成相似性较高;Alpha分析结果显示来源于同种设施的动物物种丰富度相近;Beta分析显示相同设施动物的肠道菌群差异较小,但品系对肠道菌群差异性有所影响。结论不同来源设施的饲养环境是动物肠道菌群多样性的主要影响因素,不同品系对肠道菌群多样性有一定影响。     

16S rRNA技术检测盐诱导 高血压大鼠肠道菌群的变化

目的检测高血压大鼠肠道菌群的变化,探讨正常菌群在盐诱导高血压发生发展中的作用。方法以8%高盐饮食喂养SD雄性大鼠制备高血压模型。Real-time PCR检测菌群结构的改变,同时检测血浆炎性因子IL-1β、IL-6和TNF-α水平变化。结果同对照组大鼠血压(96.00mmHg±5.74mmHg)相比盐敏感组(122.79 mmHg±6.37 mmHg)显著升高,而盐抵抗组无明显变化;实验组大鼠体重(172.00g±15.58g,164.25g±16.11g)较对照组(377.63g±32.47g)明显降低;同对照组相比实验组菌群结构发生比例倒置,即双歧杆菌(6.19±0.47,7.52±0.47 vs 8.59±0.42)、乳杆菌(6.77±0.23,7.09±0.28 vs 7.60±0.26)、拟杆菌(8.98±0.45,8.46±0.47 vs 9.99±0.73)数量降低;肠杆菌(7.93±0.20,7.78±0.29 vs 7.28±0.27)数量升高。同盐抵抗组大鼠相比,盐敏感组双歧杆菌、乳杆菌降低更加显著,但拟杆菌数量高于盐抵抗组。两实验组大鼠血浆细胞因子IL-1β、IL-6和TNF-α水平较对照组均显著升高(P0.05)。结论盐诱导高血压大鼠肠道菌群结构发生改变,盐敏感组双歧杆菌、乳杆菌和拟杆菌含量显著降低,提示其可能参与盐诱导高血压病程。     

慢性温和应激抑郁模型大鼠5-羟色胺、色氨酸和应激激素的变化

目的：通过观察慢性温和应激对大鼠行为及5-羟色胺、色氨酸、应激激素的影响,进一步阐明应激致抑郁发生的机制。方法：利用慢性不可预计温和应激（CUMS）结合行为学指标建立大鼠抑郁动物模型;高效液相检测血浆和脑5-HT、儿荼酚胺;放免方法检测血浆皮质醇换算成皮质酮含量;氨基酸分析仪检测血清色氨酸的含量。结果：①CUMS诱导8周大鼠糖水偏爱性与对照组相比明显减低（P〈0．05）;体重和旷场实验评分下降（P〈0．05）。②CUMS诱导8周大鼠大脑和血浆5-HT含量显著下降（P〈0．05）;而血清色氨酸含量与对照组相比则明显升高（P〈0．05）。③CUMS诱导8周大鼠血浆去甲肾上腺素和肾上腺素含量与对照组相比明显升高（P〈0．05）：血浆皮质酮含量与对照组相比统计学上无显著性差异（P〉0．05）。结论：利用CUMS建立的抑郁模型大鼠存在着神经内分泌紊乱,CUMS大鼠抑郁样行为的发生可能与血浆去甲肾上腺素和肾上腺素升高对色氨酸代谢的影响有关。     

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。     

槲皮素对自发性高血压大鼠血压、肠道菌群及心室重构的影响及机制研究

为了探讨槲皮素对自发性高血压大鼠(SHR)血压、肠道菌群及心室重构的影响及机制,本实验设8只Wistar Kyoto大鼠为对照组(WKY),将24只SHR随机分为模型组(SHR)、贝那普利组(Ben)、槲皮素组(Que),予以灌胃,测血压,8周后,用ELISA检测血清Toll样受体4(TLR4)、NF-κB p65浓度,用16S-V4区测序检测肠道菌群;计算心脏质量指数、左心室质量指数,用苦味酸-酸性品红法染色观察心肌纤维化,计算CVF;用Western blot和RT-PCR检测心肌组织TLR4蛋白和mRNA含量。结果显示:与WKY比较,SHR收缩压、心脏质量指数、左心室质量指数、CVF、血清TLR4、NF-κB p65以及心肌组织TLR4蛋白和mRNA、F/B值均增高,菌群丰富度下降;与SHR比较,Ben、Que均能显著降低血压,改善心肌纤维化程度,降低血清TLR4、NF-κB p65以及心肌组织TLR4蛋白和mRNA的表达,改善肠道菌群丰度。研究结果提示槲皮素可能通过调节肠道菌群,下调TLR4/NF-κB途径,进而降低SHR血压及改善心室重构。     

Chronic stress increases the reactivity of central depressor mechanisms]

The activity of noradrenergic system of lateral hypothalamus and hemodynamics were studied during acute restraint in chronically stressed and control rats. Arterial blood pressure in rest was negatively proportional to basal norepinephrine concentration in dialysate of lateral hypothalamus. Animals with high increase of norepinephrine levels in dialysate during acute stress had rapid return of arterial blood pressure to basal values while stress-induced hypertension in the beginning of restraint was the same as in rats with low increase of norepinephrine levels. Data obtained show the depressor role of noradrenergic system of lateral hypothalamus. The enhanced reactivity of noradrenergic depressor system may be one of the mechanisms providing cardiovascular adaptation to stress.     

Effect of androsole acetate on blood pressure of stress-sensitive hypertensive rats.

The basal and stress-induced blood pressure was found to decrease in rats with inherited stress sensitive hypertension (SSHR) followed by androzole acetate administration orally (30 mg/kg body weight) for eight days. The basal levels of arterial blood pressure was decreased by 17.5% and that of stress-induced animals--by 19%.     

Sex difference in norepinephrine surge in response to psychological stress through nitric oxide in rats

Psychological stress elevates blood pressure through sympathetic nerve activation. This pressor response is supposedly associated with cardiovascular events. We investigated a sex difference in the pressor response and norepinephrine surge to cage-switch stress in rats. Wistar male and female rats were catheterized for blood pressure monitoring and blood sampling. Six days post-surgery, the rats were exposed to the cage-switch stress and blood samples were collected at rest and 30 min after the start of the stress. The stress-induced pressor response was greater in the male than in the female rats. The stress significantly increased the norepinephrine level in the male, but not in the female rats. Pre-treatment with N(G)-nitro-l-arginine methyl ester (L-NAME), a nitric oxide (NO) synthase inhibitor, attenuated the norepinephrine response significantly in the male rats. There was no sex difference in the endothelial NO synthase expression in the gastrocnemius muscle. However the phosphorylation at serine 1177, a marker for eNOS activation, was higher in the male than in the female rats. These results suggest that NO is involved in the norepinephrine surge to psychological stress in the male rats, but not in the female rats. This is the first report on a sex difference in the norepinephrine surge in response to psychological stress through NO, in association with pressor response.     

Exercise induction of gut microbiota modifications in obese,non-obese and hypertensive rats

Background

Obesity is a multifactor disease associated with cardiovascular disorders such as hypertension. Recently, gut microbiota was linked to obesity pathogenesisand shown to influence the host metabolism. Moreover, several factors such as host-genotype and life-style have been shown to modulate gut microbiota composition. Exercise is a well-known agent used for the treatment of numerous pathologies, such as obesity and hypertension; it has recently been demonstrated to shape gut microbiota consortia. Since exercise-altered microbiota could possibly improve the treatment of diseases related to dysfunctional microbiota, this study aimed to examine the effect of controlled exercise training on gut microbial composition in Obese rats (n = 3), non-obese Wistar rats (n = 3) and Spontaneously Hypertensive rats (n = 3). Pyrosequencing of 16S rRNA genes from fecal samples collected before and after exercise training was used for this purpose.

Results

Exercise altered the composition and diversity of gut bacteria at genus level in all rat lineages. Allobaculum (Hypertensive rats), Pseudomonas and Lactobacillus (Obese rats) were shown to be enriched after exercise, while Streptococcus (Wistar rats), Aggregatibacter and Sutturella (Hypertensive rats) were more enhanced before exercise. A significant correlation was seen in the Clostridiaceae and Bacteroidaceae families and Oscillospira and Ruminococcus genera with blood lactate accumulation. Moreover, Wistar and Hypertensive rats were shown to share a similar microbiota composition, as opposed to Obese rats. Finally, Streptococcus alactolyticus, Bifidobacterium animalis, Ruminococcus gnavus, Aggregatibacter pneumotropica and Bifidobacterium pseudolongum were enriched in Obese rats.

Conclusions

These data indicate that non-obese and hypertensive rats harbor a different gut microbiota from obese rats and that exercise training alters gut microbiota from an obese and hypertensive genotype background.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-511) contains supplementary material, which is available to authorized users.     

Effect of ethanol on heart rate and blood pressure in nonstressed and stressed rats

The effect of ethanol on the cardiovascular system (ECG, heart rate, blood pressure) was studied in anesthetized, nonstressed or stressed rats. In anesthetized rats, ethanol showed no effect on heart rate or ECG. In nonstressed rats, ethanol sedated the animals but increased heart rate significantly. This ethanol induced tachycardia seemed the result of a direct stimulation of the sympathetic nerves to the heart. Blood pressure was not significantly affected by ethanol in these nonstressed rats. In stressed rats, marked behavioral excitation and significant increases in heart rate and blood pressure were noted. Ethanol pretreatment calmed the animals considerably during restraint. Ethanol did reduce slightly the stress-induced tachycardia but markedly reduced or antagonized stress-induced blood pressure increases. No major changes in the ECG were noted during these studies with the exception of a few individual animals which showed pathologic ECG responses to ethanol. These data show that ethanol affects cardiovascular functions differently in anesthetized, nonstressed or stressed rats, and that ethanol can significantly reduce or antagonize stress-induced behavioral excitation, tachycardia and hypertension.     

Neuropeptide Y reverses chronic stress-induced baroreflex hypersensitivity in rats

Chronic stress, as a risk factor for cardiovascular diseases, has been reported to result in elevated plasma neuropeptide Y (NPY) and be highly associated with abnormal cardiac autonomic function. This study aimed to explore the effect of NPY on the chronic stress-induced abnormal baroreceptor reflex sensitivity (BRS). Seven types of recognized stressors were used to develop chronic stress rat model. Subcutaneously implanting ALZET mini-osmotic pumps containing NPY were used to evaluate the action of NPY on the stressed male rats. We found that chronic stress showed no influence on baseline systolic blood pressure (SBP) and heart rate (HR), whereas NPY (85 μg for 30 days) could elevate baseline SBP and induce bradycardia in rats intervened by various stimuli. NPY pretreatment could preserve chronic stress-induced decreases in left ventricular systolic pressure (LVSP) and the maximum rate of change in left ventricular pressure in the isovolumic contraction period (+dp/dt(max)) but has shown no effect on left ventricular end diastolic pressure (LVEDP) and the maximum rate of change in left ventricular pressure in the isovolumic relaxation period (-dp/dt(max)). Notably, chronic stress led to baroreflex oversensitivity indicated by the elevated ratio of Δheart rate (HR)/ Δmean arterial blood pressure (MABP) in rats followed by vasoconstrictor (phenylephrine, PE) or vasodilator (sodium nitroprusside, SNP) administration, which was almost completely reversed by NPY pretreatment. The expressions of substance P (SP) and gamma aminobutyric acid A receptor (GABA(A)R) in nucleus tractus solitarius were increased in chronic stress rats, which were counteracted by NPY pretreatment. We conclude that chronic stress-induced baroreflex hypersensitivity could be blocked by NPY pretreatment. Furthermore, the altered expressions of neurotransmitters and receptors in the brainstem might contribute to this process.     

短期低剂量饮酒后戒断改变雄性大鼠肠道微生物菌群并与焦虑样行为相关

长期规律性饮酒会改变肠道微生物菌群构成,并影响焦虑抑郁样行为。而短期低剂量饮酒后戒断是否对肠道菌群产生影响及其与酒精戒断后焦虑样行为是否有关,尚无系统研究。本研究以SD大鼠为研究对象,将30只雄性大鼠随机分为酒精处理组 (Ethanol-C)、对照组 (Ethanol-0)和酒精戒断组 (Ethanol-2),每组各10只。酒精处理组每d以1次酒精(5 g/kg, 25% V/V)连续灌胃14 d;对照组以等量蒸馏水灌胃,酒精戒断组每d以等量酒精连续灌胃14 d,其后戒断1 d。采集所有实验动物粪便,利用高通量测序方法分析慢性酒精刺激后对大鼠肠道微生物多样性及群落结构的影响,通过旷场实验和高架十字迷宫测定大鼠焦虑样行为,并分析肠道微生物与酒精戒断致焦虑样行为的相关性。肠道微生物分类学分析发现,酒精戒断组大鼠肠道微生物的组成和丰度与对照组和酒精处理组比较均出现明显差异。酒精戒断组肠道微生物Alpha多样性与对照组和酒精处理组无显著差异,而微生物群落结构显著不同。酒精戒断组大鼠的开臂时间百分比和自发活动距离显著降低 (P<0.05),且与拟杆菌属（Bacteroides）、梭杆菌属（Fusobacterium）、大肠杆菌志贺菌（Escherichia-Shigella）显著正相关 (P<0.05),而与瘤胃球菌（Rumenococcus）、毛螺旋菌（Trichospirillum）等菌属显著负相关 (P<0.05)。 本研究结果提示,短期低剂量酒精戒断不影响肠道微生物的Alpha多样性,但能够改变大鼠肠道微生物组成丰度及群落结构,且大鼠酒精戒断后的肠道微生物与大鼠焦虑样行为具有相关性。本研究结果明确了肠道微生物在短期低剂量酒精戒断过程中的变化情况,为酒精戒断致焦虑行为的研究提供新的方向。     

Maternal resveratrol therapy protected adult rat offspring against hypertension programmed by combined exposures to asymmetric dimethylarginine and trimethylamine-N-oxide

Resveratrol, a phytochemical, has shown antioxidant properties and potential benefits in hypertension. Asymmetric dimethylarginine (ADMA)-related nitric oxide deficiency and gut microbiota-derived metabolite trimethylamine-N-oxide (TMAO) have been linked to hypertension. We aimed to test whether maternal resveratrol therapy would protect adult offspring against hypertension programmed by prenatal exposure to ADMA and TMAO. Pregnant Sprague-Dawley rats received ADMA 10 mg/kg/day (A), TMAO 0.65 mg/hr (T), ADMA+TMAO (AT), or vesicle (CV). One group of ADMA+TMAO-exposed rats received 50 mg/L of resveratrol in drinking water during pregnancy and lactation periods (ATR). Male offspring (n = 8/group) were assigned to five groups: CV, A, T, AT, and ATR. Rats were killed at 12 weeks of age. ADMA exposure caused the elevation of blood pressure in 12-week-old male offspring, which was exacerbated by TMAO exposure. Treatment with resveratrol rescued hypertension programmed by combined ADMA and TMAO exposure. This was accompanied by alterations in the compositions of gut microbiota and increased fecal butyrate levels. Both the abundance of the butyrate-producing genera Lachnospiraceae and Ruminococcaceae were augmented by resveratrol. Meanwhile, resveratrol therapy significantly increased the abundance of the Cyanobiaceae and Erysipelotrichaceae families. Moreover, the protective effects of resveratrol were related to the mediation of the renin-angiotensin system . Our data provide new insights into the protective mechanisms of resveratrol against hypertension programmed by ADMA and TMAO, including regulation of gut microbiota and their metabolites, the renin-angiotensin system, and nitric oxide pathway. Resveratrol might be a potential reprogramming strategy to protect against the hypertension of developmental origins.     

The Gut Microbiota Modulates Glycaemic Control and Serum Metabolite Profiles in Non-Obese Diabetic Mice

Islet autoimmunity in children who later progress to type 1 diabetes is preceded by dysregulated serum metabolite profiles, but the origin of these metabolic changes is unknown. The gut microbiota affects host metabolism and changes in its composition contribute to several immune-mediated diseases; however, it is not known whether the gut microbiota is involved in the early metabolic disturbances in progression to type 1 diabetes. We rederived non-obese diabetic (NOD) mice as germ free to explore the potential role of the gut microbiota in the development of diabetic autoimmunity and to directly investigate whether the metabolic profiles associated with the development of type 1 diabetes can be modulated by the gut microbiota. The absence of a gut microbiota in NOD mice did not affect the overall diabetes incidence but resulted in increased insulitis and levels of interferon gamma and interleukin 12; these changes were counterbalanced by improved peripheral glucose metabolism. Furthermore, we observed a markedly increased variation in blood glucose levels in the absence of a microbiota in NOD mice that did not progress to diabetes. Additionally, germ-free NOD mice had a metabolite profile similar to that of pre-diabetic children. Our data suggest that germ-free NOD mice have reduced glycaemic control and dysregulated immunologic and metabolic responses.     

Variations of brain histamine levels in germ-free and nephrectomized rats

The influence of nephrectomy on brain and peripheral tissue histamine and on brain norepinephrine, dopamine, serotonin, and 5-hydroxyindoleacetic acid was studied in germ-free and conventionally housed rats. The conventional controls had higher levels of histamine in the hypothalamus than the germ-free control animals, but no differences existed for histamine in whole brain minus the hypothalamus or in peripheral tissues. Nephrectomy increased brain histamine and 5-hydroxyindoleacetic acid levels in both germ-free and conventional rats, but had no effect on norepinephrine, dopamine or serotonin. In contrast, the histamine level in the heart of the nephrectomized germ-free animals was lower than that for germ-free controls. There were no changes in the heart or liver histamine levels of the conventional nephrectomized rats.