母婴分离对新生鼠成年后内脏疼痛敏感性影响及机制研究

目的 探讨新生期母婴分离（NMS）对幼鼠成年后内脏痛觉敏感性影响及其机制.方法 建立新生期NMS动物模型,以受孕的Wistar大鼠为研究对象,待其生产后,每笼饲养12只新生鼠和1只哺乳期母鼠.实验分为NMS组（n=12）和对照组（N）（n=12）.NMS组在出生后2～21 d,每天同时间分离新生鼠和母鼠3 h.N组不做分离处理.在2个月时给予结肠直肠扩张（CRD）,通过观察大鼠在不同压力下CRD刺激后的腹壁撤退反射（AWR）评分,进行内脏痛觉敏感性评价;取远端结肠组织采用免疫组织化学技术检测5-羟色胺（5-HT）及其受体的表达情况.结果 随CRD增加,两组大鼠AWR评分增加;与对照组相比,CRD后NMS组AWR评分明显增加,差异有统计学意义（P〈0.05）.与对照组相比,CRD后,NMS组5-HT及其受体的表达显著增加,差异有统计学意义（P〈0.05）.结论 新生期NMS使成年大鼠CRD时大鼠痛阈下降,出现慢性内脏痛觉高敏感性,5-HT及其受体参与了内脏伤害性刺激的神经反应.     

Probiotic Lactobacillus reuteri alleviates the response to gastric distension in rats

Probiotic lactic acid bacteria have been reported to alleviate symptoms in patients with irritable bowel syndrome. However, they have not been tested for use in functional gastric disease. We therefore investigated if strains previously shown to protect from response to colorectal distension (CRD) in rats also modulate response to gastric distension (GD). Healthy, male Sprague-Dawley rats were treated with viable, heat-killed, gamma-irradiated Lactobacillus reuteri or viable Lactobacillus plantarum wild type (WT), L. plantarum Dltˉmutant, conditioned medium or medium control (9 d), and subjected to GD under anesthesia using an i.g. Teflon catheter. Effects were measured by heart rate (HR) changes during noxious distension (60 mm Hg) compared to baseline HR values. We also investigated the localization of viable, green fluorescent protein-transfected bacteria in the stomach mucosa. Viable L. reuteri decreased the bradycardia induced by noxious GD compared to placebo controls (P < 0.001). Heat-killed or gamma-irradiated L. reuteri and conditioned medium did not have a protective effect in GD. Viable L. plantarum WT and Dltˉmutant, previously shown to be effective antinociceptive agents in CRD, showed no protective effect in GD. All viable bacteria were associated with the pars glandularis of the rat stomach. Thus, we conclude that the antinociceptive mechanisms of action of probiotic bacteria differ between the stomach and the colon. Symptom alleviation cannot be attributed to the localization of the bacteria in the stomach. Information derived from effects of CRD cannot be extrapolated to effects in the stomach, which are likely to be strain and organ specific.     

Microbial content and antibiotic susceptibility of bacterial isolates from yoghurts

A total of 83 dairy products form the Greek market were examined for their bacterial populations and results were compared with the label information. The antibiotic susceptibility of the bacterial isolates was also examined. The status labeling of the yoghurts and the dairy desserts was found insufficient. The 89.8% of the cocci was found susceptible against all the 12 antibiotics examined. Lactobacillus spp. strains exhibited some kind of resistance to one or more antibiotics. The isolates of Lactobacillus delbrueckii showed resistance to one to four antibiotics, the isolates of Lactobacillus acidophilus were resistant to one to three antibiotics, while the Lactobacillus paracasei strains were resistant to four or five antibiotics. Finally, multi-resistant strains (six to nine antibiotics) were found only among the Lactobacillus rhamnosus strains.     

The incidence of necrotizing enterocolitis is increased following probiotic administration to preterm pigs

Preterm birth and necrotizing enterocolitis (NEC) is associated with inappropriate gut colonization and immunity, which may be improved by probiotic bacteria. Using a preterm pig model of NEC, we investigated the effects of probiotics on intestinal structure, function, microbiology, and immunology in the immediate postnatal period. Just after birth, caesarean-delivered preterm pigs were inoculated with Lactobacillus paracasei, Bifidobacteria animalis, and Streptococcus thermophilus (total 2.4 × 10(10)/d) either as live (ProLive, n = 14) or gamma-irradiated dead bacteria (ProDead, n = 12) and compared with controls (n = 14). All pigs received parenteral nutrition for 2 d followed by enteral formula feeding until tissue collection on d 5. Compared with control pigs, intestinal weight was lower and NEC incidence was higher in both groups given probiotics (64-67 vs. 14%; P<0.01). Hexose absorption, brush border enzyme activities, and gut barrier function were lower in the ProDead group compared with the other groups (P < 0.05), whereas live probiotics induced higher expression of the proinflammatory cytokines IL-1α and IL-6 (P < 0.05). Probiotics minimally affected gut colonization, except that live probiotics induced a higher density of B. animalis and lower bacterial diversity in the distal intestinal mucosa and lower SCFA concentrations in the colon (P < 0.05). The detrimental effects of probiotic bacteria in this study may relate to the specific strain and dose combination and may have involved the very immature gut immune system and low NEC incidence in the control group. It remains to be determined whether similar adverse responses to probiotics occur in preterm infants.     

A synbiotic combination of resistant starch and Bifidobacterium lactis facilitates apoptotic deletion of carcinogen-damaged cells in rat colon

Recent reports suggest that combinations of prebiotics and probiotics may be protective against colorectal cancer. We examined in rats the effects of probiotic bacteria, resistant starch (RS), and their interaction on luminal and epithelial events of relevance to the development of colorectal cancer. Lyophilized cultures (1 x 10(10) cfu/g) of Lactobacillus acidophilus and/or Bifidobacterium lactis were added at a concentration of 1% by weight to a semipurified diet containing either low-RS (no supplemented RS) or moderate-RS (10% Hi-maize) and fed to male Sprague-Dawley rats for 4 wk. Experimental end-points included cecal bacterial enumeration, fecal and cecal pH, SCFA levels, cell proliferation, and the acute apoptotic response to a genotoxic carcinogen (AARGC; measured 6 h after a single azoxymethane injection). A significant interaction between dietary RS and supplemental bacteria was observed for the AARGC in the colon and fecal pH (P < 0.01). Rats fed the moderate-RS diet in combination with B. lactis had a significantly greater AARGC in the colon than those fed that diet without B. lactis. Fecal pH was elevated in the moderate-RS fed rats supplemented with bacteria. The moderate-RS diet increased cell proliferation and crypt column height (P < 0.001) compared with the low-RS diet. SCFA levels and numbers of bifidobacteria and lactobacilli species were also increased (P < 0.001) by the moderate-RS diet, whereas pH levels and total coliforms were lowered (P < 0.001). The synbiotic combination of RS and B. lactis significantly facilitated the apoptotic response to a genotoxic carcinogen in the distal colon of rats. It appears likely that ingested RS acts as a metabolic substrate, thus creating the right conditions for B. lactis to exert its proapoptotic action. Because the synbiotic combination of these agents facilitates the apoptotic response to DNA damage by a cancer initiator in the colon of rats, it warrants further study for its capacity to protect against colorectal cancer.     

Cell-Free Supernatants from Probiotic Lactobacillus casei and Lactobacillus rhamnosus GG Decrease Colon Cancer Cell Invasion In Vitro

Probiotics have been shown to have a preventative role in colorectal carcinogenesis but research concerning their prophylactic potential in the later stages of colorectal cancer, specifically metastasis is limited. This study explored the potential of cell-free supernatants (CFS) from 2 probiotic Lactobacillus sp., Lactobacillus casei and Lactobacillus rhamnosus GG, to inhibit colon cancer cell invasion by influencing matrix metalloproteinase-9 (MMP-9) activity and levels of the tight junction protein zona occludens-1 (ZO-1) in cultured metastatic human colorectal carcinoma cells. HCT-116 cells were treated with CFS from L. casei, L. rhamnosus, or Bacteroides thetaiotaomicron (a gut commensal); or with uninoculated bacterial growth media. Treatment with CFS from both Lactobacillus sp. decreased colorectal cell invasion but treatment with CFS from B. thetaiotaomicron did not. CFS from both Lactobacillus sp. decreased MMP-9 and increased ZO-1 protein levels. L. rhamnosus CFS also lowered MMP-9 activity. To begin elucidating the secreted bacterial factor conveying these responses, Lactobacillus sp. CFS were fractionated into defined molecular weight ranges and cell invasion assessed. Fractionation revealed that the inhibitory activity was contained primarily in the >100?kDa and 50-100?kDa fractions, suggesting the inhibitory compound may be a macromolecule such as a protein, nucleic acid, or a polysaccharide.     

Long-term consumption of saponins derived from Platycodi radix (22 years old) enhances hepatic insulin sensitivity and glucose-stimulated insulin secretion in 90 % pancreatectomized diabetic rats fed a high-fat diet

Crude saponins derived from Chinese Platycodi radix have been reported to prevent increases in body weight and liver TAG in mice fed a high-fat diet. We investigated the effects of an extract (PR) taken from Korean Platycodi radix, which is cultivated for 22 years in the ground (Jangsaeng doraji), and its saponins (PRS) on insulin resistance and glucose-stimulated insulin secretion in 90 % pancreatectomized diabetic rats fed high-fat diets. Four groups were orally supplemented with 2 g PR, 0.2 g PRS, 20 mg rosiglitazone (positive control) or 0.5 g cellulose (negative control) per kg body weight on a daily basis for 8 weeks. We found that PRS lowered body weight, visceral fat mass and serum leptin levels in pancreatectomized rats in comparison to the control. PR enhanced first- and second-phase insulin secretion while PRS stimulated only first-phase insulin secretion. Glucose infusion rates to maintain euglycaemia at hyperinsulinaemic states decreased in a descending order of rosiglitazone, PRS, PR and control, but they increased hepatic glucose output in the same order. This reduction was associated with the storage of decreased TAG and increased glycogen, which was a result of enhanced tyrosine phosphorylation of anti-insulin receptor substrate-2 and serine473 phosphporylation of protein kinase B (PKB, Akt). Improved hepatic insulin signalling led to decreased phosphoenolpyruvate carboxykinase expression and reduced hepatic glucose output accordingly. In conclusion, PRS principally improves glucose homeostasis by enhancing hepatic insulin sensitivity as a consequence of reducing fat storage and stimulating insulin signalling in diabetic rats. In addition, PR contains components that promote glucose-stimulated insulin secretion.     

Black Raspberries and Their Anthocyanin and Fiber Fractions Alter the Composition and Diversity of Gut Microbiota in F-344 Rats

Natural compounds can alter the diversity and composition of the gut microbiome, potentially benefiting our health. We previously demonstrated chemopreventive effects of black raspberries (BRBs) in colorectal cancer, which is associated with gut dysbiosis. To investigate the effects of whole BRBs and their fractions on gut microbiota, we fed F-344 rats a control diet, 5% BRBs, the BRB anthocyanin fraction, or the BRB residue fraction for 6 weeks. Feces were collected at baseline and at weeks 3 and 6, and bacterial sequence counts were analyzed. We observed distinct patterns of microbiota from different diet groups. Beta diversity analysis suggested that all diet groups exerted time-dependent changes in the bacterial diversity. Hierarchical clustering analysis revealed that post-diet fecal microbiota was segregated from baseline fecal microbiota within each diet. It is interesting to note that fractions of BRBs induced different changes in gut bacteria compared to whole BRBs. The abundance of specific microbial species known to have anti-inflammatory effects, such as Akkermansia and Desulfovibrio, was increased by whole BRBs and their residue. Further, butyrate-producing bacteria, e.g., Anaerostipes, were increased by whole BRBs. Our results suggest that whole BRBs and their fractions alter the gut microbiota in ways that could significantly influence human health.     

Effect of lactobacilli on paracellular permeability in the gut

Paracellular permeability is determined by the complex structures of junctions that are located between the epithelial cells. Already in 1996, it was shown that the human probiotic strain Lactobacillus plantarum 299v and the rat-originating strain Lactobacillus reuteri R2LC could reduce this permeability in a methotrexate-induced colitis model in the rat. Subsequently, many animal models and cell culture systems have shown indications that lactobacilli are able to counteract increased paracellular permeability evoked by cytokines, chemicals, infections, or stress. There have been few human studies focusing on the effect of lactobacilli on intestinal paracellular permeability but recently it has been shown that they could influence the tight junctions. More precisely, short-term administration of L. plantarum WCSF1 to healthy volunteers increased the relocation of occludin and ZO-1 into the tight junction area between duodenal epithelial cells.     

Ingested probiotics reduce nasal colonization with pathogenic bacteria (Staphylococcus aureus,Streptococcus pneumoniae,and beta-hemolytic streptococci)

BACKGROUND: As a bacterial reservoir, the nose may harbor potentially pathogenic bacteria (PPB: Staphylococcus aureus, Streptococcus pneumoniae, beta-hemolytic streptococci, and Haemophilus influenzae). In patients carrying PPB, antiseptic regimens could be crucial for infection control after major operations on or injuries of the head, nasal sinuses, or lungs. Such regimens may also be important for diabetic patients and persons receiving hemodialysis, in intensive care units, or with impaired immunity due to various other causes. OBJECTIVE: We tested a possible effect of the ingestion of probiotics on the bacterial flora of the nose. DESIGN: In an open, prospective trial, 209 volunteers were randomly assigned to consume either a probiotic, fermented milk drink [65 mL with Lactobacillus GG (ATCC 53103), Bifidobacterium sp B420, Lactobacillus acidophilus 145, and Streptococcus thermophilus; n = 108] or standard yogurt (180 g; n = 101) daily for 3 wk. Nasal microbial flora were analyzed on days 1, 21, and 28. The microbial examination was blinded to the source of the samples. RESULTS: We found a significant reduction (19%; P < 0.001) in the occurrence of nasal PPB in the group who consumed the probiotic drink but not in the group who consumed yogurt. The effect was mainly on gram-positive bacteria, which decreased significantly (P < 0.05). CONCLUSIONS: The results indicate that regular intake of probiotics can reduce PPB in the upper respiratory tract. The results also indicate a linkage of the lymphoid tissue between the gut and the upper respiratory tract.     

Lactobacillus GG treatment ameliorates alcohol-induced intestinal oxidative stress, gut leakiness, and liver injury in a rat model of alcoholic steatohepatitis

Because only 30% of alcoholics develop alcoholic liver disease (ALD), a factor other than heavy alcohol consumption must be involved in the development of alcohol-induced liver injury. Animal and human studies suggest that bacterial products, such as endotoxins, are the second key co-factors, and oxidant-mediated gut leakiness is one of the sources of endotoxemia. Probiotics have been used to prevent and treat diseases associated with gut-derived bacterial products and disorders associated with gut leakiness. Indeed, “probiotic” Lactobacillus rhamnosus has been successfully used to treat alcohol-induced liver injury in rats. However, the mechanism of action involved in the potential beneficial effects of L. rhamnosus in alcohol liver injury is not known. We hypothesized that probiotics could preserve normal barrier function in an animal model of ALD by preventing alcohol-induced oxidative stress and thus prevent the development of hyperpermeability and subsequent alcoholic steatohepatitis (ASH). Male Sprague-Dawley rats were gavaged with alcohol twice daily (8 gm/kg) for 10 weeks. In addition, alcoholic rats were also treated with once daily gavage of either 2.5 × 10⁷ live L. rhamnosus Gorbach-Goldin (LGG) or vehicle (V). Intestinal permeability (baseline and at 10 weeks) was determined using a sugar bolus and GC analysis of urinary sugars. Intestinal and liver tissues were analyzed for markers of oxidative stress and inflammation. In addition, livers were assessed histologically for severity of ASH and total fat (steatosis). Alcohol + LGG (ALC + LGG)-fed rats had significantly (P ≤ .05) less severe ASH than ALC + V-fed rats. L. rhamnosus Gorbach-Goldin also reduced alcohol-induced gut leakiness and significantly blunted alcohol-induced oxidative stress and inflammation in both intestine and the liver. L. rhamnosus Gorbach-Goldin probiotic gavage significantly ameliorated ASH in rats. This improvement was associated with reduced markers of intestinal and liver oxidative stress and inflammation and preserved gut barrier function. Our study provides a scientific rationale to test probiotics for treatment and/or prevention of alcoholic liver disease in man.     

Effect of Colonic Bacterial Metabolites on Caco-2 Cell Paracellular Permeability In Vitro

One common effect of tumor promoters is increased tight junction (TJ) permeability. TJs are responsible for paracellular permeability and integrity of the barrier function. Occludin is one of the main proteins responsible for TJ structure. This study tested the effects of physiological levels of phenol, ammonia, primary bile acids (cholic acid, CA, and chenodeoxycholic acid, CDCA), and secondary bile acids (lithocholic acid, LCA, and deoxycholic acid, DCA) on paracellular permeability using a Caco-2 cell model. Paracellular permeability of Caco-2 monolayers was assessed by transepithelial electrical resistance (TER) and the apical to basolateral flux of [ ¹⁴ C]-mannitol. Secondary, but not primary, bile acids increased permeability as reflected by significantly decreased TER and increased mannitol flux. Both phenol and ammonia also increased permeability. The primary bile acid CA significantly increased occludin expression (P < 0.05), whereas CDCA had no significant effect on occludin expression as compared to the negative control. The secondary bile acids DCA and LCA significantly increased occludin expression (P < 0.05), whereas phenol had no significant effect on the protein expression as compared to the negative control. This suggests that the increased permeability observed with LCA, DCA, phenol, and ammonia was not related to an effect on occludin expression. In conclusion, phenol, ammonia, and secondary bile acids were shown to increase paracellular permeability and reduce epithelial barrier function at doses typical of levels found in fecal samples. The results contribute to the evidence these gut microflora-generated products have tumor-promoting activity.     

Effect of colonic bacterial metabolites on Caco-2 cell paracellular permeability in vitro

One common effect of tumor promoters is increased tight junction (TJ) permeability. TJs are responsible for paracellular permeability and integrity of the barrier function. Occludin is one of the main proteins responsible for TJ structure. This study tested the effects of physiological levels of phenol, ammonia, primary bile acids (cholic acid, CA, and chenodeoxycholic acid, CDCA), and secondary bile acids (lithocholic acid, LCA, and deoxycholic acid, DCA) on paracellular permeability using a Caco-2 cell model. Paracellular permeability of Caco-2 monolayers was assessed by transepithelial electrical resistance (TER) and the apical to basolateral flux of [14C]-mannitol. Secondary, but not primary, bile acids increased permeability as reflected by significantly decreased TER and increased mannitol flux. Both phenol and ammonia also increased permeability. The primary bile acid CA significantly increased occludin expression (P < 0.05), whereas CDCA had no significant effect on occludin expression as compared to the negative control. The secondary bile acids DCA and LCA significantly increased occludin expression (P < 0.05), whereas phenol had no significant effect on the protein expression as compared to the negative control. This suggests that the increased permeability observed with LCA, DCA, phenol, and ammonia was not related to an effect on occludin expression. In conclusion, phenol, ammonia, and secondary bile acids were shown to increase paracellular permeability and reduce epithelial barrier function at doses typical of levels found in fecal samples. The results contribute to the evidence these gut microflora-generated products have tumor-promoting activity.     

Biochemical and Metabolical Pathways Associated with Microbiota-Derived Butyrate in Colorectal Cancer and Omega-3 Fatty Acids Implications: A Narrative Review

Knowledge regarding the influence of the microbial community in cancer promotion or protection has expanded even more through the study of bacterial metabolic products and how they can modulate cancer risk, which represents an extremely challenging approach for the relationship between intestinal microbiota and colorectal cancer (CRC). This review discusses research progress on the effect of bacterial dysbiosis from a metabolic point of view, particularly on the biochemical mechanisms of butyrate, one of the main short chain fatty acids (SCFAs) with anti-inflammatory and anti-tumor properties in CRC. Increased daily intake of omega-3 polyunsaturated fatty acids (PUFAs) significantly increases the density of bacteria that are known to produce butyrate. Omega-3 PUFAs have been proposed as a treatment to prevent gut microbiota dysregulation and lower the risk or progression of CRC.     

Improvement of the probiotic effect of micro-organisms by their combination with maltodextrins,fructo-oligosaccharides and polyunsaturated fatty acids

Probiotics could represent an effective alternative to the use of synthetic substances in nutrition and medicine. The data concerning the efficacy of probiotics are often contradictory. This paper focuses on the enhancement of the efficacy of probiotics by their combination with synergistically acting components of natural origin. Maltodextrins can be obtained by enzymatic hydrolysis of starch and are suitable for consumption. Administration of Lactobacillus paracasei together with maltodextrin decreased the number of Escherichia coli colonising the jejunal mucosa of gnotobiotic piglets by 1 logarithm compared to the control group. Fructo-oligosaccharides (FOS) are naturally occurring oligosaccharides, mainly of plant origin. L. paracasei administered in combination with FOS significantly increased counts of Lactobacillus spp., Bifidobacterium spp., total anaerobes and total aerobes compared to the control group as well as the L. paracasei group. It also significantly decreased Clostridium and Enterobacterium counts in the faeces of the weanling piglets compared with the control group. Dietary lipids influence the gastrointestinal microbiota and specifically the population of lactic acid bacteria. In gnotobiotic piglets the oral administration of an oil containing polyunsaturated fatty acids (PUFA) significantly increased the number of L. paracasei adhering to jejunal mucosa compared to the control group. Our results showed that maltodextrin KMS X-70 and PUFA can be used to enhance the effect of probiotic micro-organisms in the small intestine, and similarly FOS enhance the effect of probiotic micro-organisms in the large intestine.     

Consumption of Dietary Fiber with Different Physicochemical Properties during Late Pregnancy Alters the Gut Microbiota and Relieves Constipation in Sow Model

Constipation is a common problem in sows and women during late pregnancy. Dietary fiber has potential in the regulation of intestinal microbiota, thereby promoting intestinal motility and reducing constipation. However, the effects of fibers with different physicochemical properties on intestinal microbe and constipation during late pregnancy have not been fully explored. In this study, a total of 80 sows were randomly allocated to control and one of three dietary fiber treatments from day 85 of gestation to delivery: LIG (lignocellulose), PRS (resistant starch), and KON (konjaku flour). Results showed that the defecation frequency and fecal consistency scores were highest in PRS. PRS and KON significantly increased the level of gut motility regulatory factors, 5-hydroxytryptamine (5-HT), motilin (MTL), and acetylcholinesterase (AChE) in serum. Moreover, PRS and KON promoted the IL-10 level and reduced the TNF-α level in serum. Furthermore, maternal PRS and KON supplementation significantly reduced the number of stillborn piglets. Microbial sequencing analysis showed that PRS and KON increased short-chain fatty acids (SCFAs)-producing genera Bacteroides and Parabacteroides and decreased the abundance of endotoxin-producing bacteria Desulfovibrio and Oscillibacter in feces. Moreover, the relative abundance of Turicibacter and the fecal butyrate concentration in PRS were the highest. Correlation analysis further revealed that the defecation frequency and serum 5-HT were positively correlated with Turicibacter and butyrate. In conclusion, PRS is the best fiber source for promoting gut motility, which was associated with increased levels of 5-HT under specific bacteria Turicibacter and butyrate stimulation, thereby relieving constipation. Our findings provide a reference for dietary fiber selection to improve intestinal motility in late pregnant mothers.     

Role of Probiotics in Modulating Human Gut Microbiota Populations and Activities in Patients with Colorectal Cancer—A Systematic Review of Clinical Trials

Background: Growing attention has been given to the role of nutrition and alterations of microbial diversity of the gut microbiota in colorectal cancer (CRC) pathogenesis. It has been suggested that probiotics and synbiotics modulate enteric microbiota and therefore may be used as an intervention to reduce the risk of CRC. The aim of this study was to evaluate the influence of probiotics/synbiotics administration on gut microbiota in patients with CRC. Methods: PubMed, Scopus, and Web of Science were searched between December 2020 and January 2021. Randomized controlled trials (RCTs) recruiting adults with CRC, who have taken probiotics/synbiotics for at least 6 days were included. Changes in gut microbiota and selected biochemical and inflammatory parameters (i.e., hsCRP, IL-2, hemoglobin) were retrieved. Results: The search resulted in 198 original research articles and a final 6 were selected as being eligible, including 457 subjects. The median age of patients was 65.4 years old and they were characterized by the median BMI value: 23.8 kg/m². The literature search revealed that probiotic/synbiotic administration improved enteric microbiota by increasing the abundance of beneficial bacteria such as Lactobacillus, Eubacterium, Peptostreptococcus, Bacillus and Bifidobacterium, and decreased the abundance of potentially harmful bacteria such as Fusobacterium, Porhyromonas, Pseudomonas and Enterococcus. Additionally, probiotic/synbiotic intervention improved release of antimicrobials, intestinal permeability, tight junction function in CRC patients. Conclusions: The use of probiotics/synbiotics positively modulates enteric microbiota, improves postoperative outcomes, gut barrier function and reduces inflammatory parameters in patients suffering from CRC.     

Prolonged intake of fructo-oligosaccharides induces a short-term elevation of lactic acid-producing bacteria and a persistent increase in cecal butyrate in rats

While the prebiotic effects of fructo-oligosaccharides (FOS), short-chain polymers of fructose, have been thoroughly described after 2-3 wk of ingestion, effects after intake for several months are unknown. We tested the hypothesis that these effects would differ after ingestion for short and long periods in rats. Rats were fed a basal low-fiber diet (Basal) or the same diet containing 9 g/100 g of FOS for 2, 8 or 27 wk, and cecal contents were collected at the end of each time period. Cecal short-chain fatty acid concentration was higher in rats fed FOS than in those fed Basal, and this effect persisted over time: 83.8 +/- 4.1 vs. 62.4 +/- 6.5 micromol/g at 2 wk and 103.5 +/- 5.8 vs. 73.2 +/- 7.4 micromol/g at 27 wk (P < 0.05). The molar butyrate ratio was higher in rats fed FOS regardless of the time period (14.8 +/- 0.6% vs. 6.7 +/- 1.1% at 27 wk, P < 0.05). Lactate concentration in rats fed FOS was elevated after 2 wk and then decreased: 63.5 +/- 21.6 micromol/g at 2 wk vs. 8.8 +/- 3.3 micromol/g at 8 wk (P < 0.05). After 2 wk, FOS increased the concentrations of total lactic acid-producing bacteria, and Lactobacillus sp. (P < 0.05), without modifying total anaerobes. However, most of these effects were abolished after 8 and 27 wk of FOS consumption. In the long term, the FOS-induced increase in intestinal lactic acid-producing bacteria was lost, but the butyrogenic properties of FOS were maintained.     

Ingestion of (n-3) fatty acids augments basal and platelet activating factor-induced permeability to dextran in the rat mesenteric vascular bed

Loss of intestinal barrier function and subsequent edema formation remains a serious clinical problem leading to hypoperfusion, anastomotic leakage, bacterial translocation, and inflammatory mediator liberation. The inflammatory mediator platelet activating factor (PAF) promotes eicosanoid-mediated edema formation and vasoconstriction. Fish oil-derived (n-3) fatty acids (FA) favor the production of less injurious eicosanoids but may also increase intestinal paracellular permeability. We hypothesized that dietary (n-3) FA would ameliorate PAF-induced vasoconstriction and enhance vascular leakage of dextran tracers. Rats were fed either an (n-3) FA-rich diet (EPA-rich diet; 4.0 g/kg EPA, 2.8 g/kg DHA) or a control diet (CON diet; 0.0 g/kg EPA and DHA) for 3 wk. Subsequently, isolated and perfused small intestines were stimulated with PAF and arterial pressure and the translocation of fluid and macromolecules from the vasculature to lumen and lymphatics were analyzed. In intestines of rats fed the EPA-rich diet, intestinal phospholipids contained up to 470% more EPA and DHA at the expense of arachidonic acid (AA). The PAF-induced increase in arterial pressure was not affected by the EPA-rich diet. However, PAF-induced fluid loss from the vascular perfusate was higher in intestines of rats fed the EPA-rich diet. This was accompanied by a greater basal loss of dextran from the vascular perfusate and a higher PAF-induced transfer of dextran from the vasculature to the lumen (P = 0.058) and lymphatics. Our data suggest that augmented intestinal barrier permeability to fluid and macromolecules is a possible side effect of (n-3) FA-rich diet supplementation.