促进猪生长的新探讨(二)

前生命期物(Probiotics) 前生命期物现巳广泛用以替代日粮中所使用的抗菌素物质。前生命期物在动物消化道内对微生物有着与抗菌素相反的作用。抗菌素在动物消化道内通过抑制和破坏细菌来控制微生物群体,用前生命期物实际是引入活的细菌于肠道内。

Influences of enteral nutrition combined with probiotics on gut microflora and barrier function of rats with abdominal infection

AIM： To investigate the influences of enteral, parenteral nutrition and probiotics delivered by gut on intestinal microecology, epithelial tight junctions, immune and barrier function of rats with abdominal infection. METHODS： Rat abdominal infection models established with cecal ligation and perforation method, were divided into three groups： parenteral nutrition （PN group, n = 7）, PN＋enteral nutrition （EN group, n = 7） and PN ＋ EN ＋ probiotics （probiotics group, n = 7） via the needle jejunostomy and neck vein for five days. The total nutritional supplement of the three groups was isonitrogenic and isocaloric. Probiotics was delivered by jejunostomy 10 mL/d （1 x 10^8 cfu/mL）. The rats were killed on the sixth day. The feces in the cecum were cultured for anaerobic bacterial growth and analyzed with bacterial group DNA fingerprint profile with random amplified polymorphic DNA. The transmembrane binding proteins （occludin） and IgA level in plasma cells of intestine epithelium in colon and terminal ileum were measured by an immunohistochemistry method. The ultrastructure of intestinal epithelial tight junctions in colon and small intestine was observed by electronmicroscopy. Vena cava blood and the homogenated tissue of liver, lung and mesenteric lymph nodes were cultured to determine the bacterial translocations, and endotoxin in the blood from portal vein was detected. RESULTS： （1） The amount of bacteria of gut species in EN group and probiotic group was higher than that in PN group. The DNA-proflles in EN group and probiotic group were similar to that of normal rats. The number of DNAprofiles in probiotics group was much more than that in PN group and EN group. Moreover, there were strange stripes in PN group. （2） The expression of occludin and IgA in the small and large intestine in EN group （2.309 ± 0.336, 15.440 ± 2.383） and probiotic group （2.938 ± 0.515, 16.230 ± 3.183） was improved as compared with PN group （1.207 ± 0.587, P 〈 0.05, 11.189 ± 2.108, P 〈 0.01）. The expression of occludin in probiotic group （intestine： 2.93 ± 0.515; cecum： 3.40 ± 0.617） was higher than that in EN group （intestine： 2.309 ± 0.336; cecum： 2.076 ± 0.670; P 〈 0.05）. The expression of IgA, especially in EN group （intestine： 15.440 ± 2.383） and probiotic EN group （large intestine： 12.516 ± 1.542） significantly increased as compared with PN group （intestine： 11.189 ± 2.108; cecum： 10.160 ± 1.643; P 〈 0.01）. The intestinal epithelial tight junctions and microvilli of the probiotic group were more intact than those in the PN group. （3） The bacterial translocations in blood, liver, lung and mesenteric lymph nodes, and the levels of endotoxin were significantly reduced in probiotic （0.082 ± 0.029） and EN （0.125 ± 0.040） groups as compared with PN group （0.403 ± 0.181, P 〈 0.05）. CONCLUSION： Application of EN combined with probiotics could improve the expression of transmembrane binding proteins （occludin） and IgA, correct the intestinal flora disturbance, maintain gut barrier functions and tight junctions, and reduce the occurrence of gut bacterial translocation.

Probiotics and prebiotics in chronic inflammatory bowel diseases

The prokaryotic and eukaryotic cells of the colon exist in a highly complex, but harmonious relationship. Disturbances in this remarkable symbiosis can result in the development of inflammatory bowel diseases (IBD). Although the etiology of IBD is not entirely understood, it is known that the chronic inflammation of Crohn’s disease, ulcerative colitis and chronic pouchitis are a result of an overly aggressive immune response to the commensal intestinal flora in genetically susceptible hosts. Recent studies have enhanced our ability to understand the interaction between the host and its intestinal microflora and the role the microflora plays in maintaining intestinal homeostasis. As we begin to understand the benefi ts conferred to the intestine by the microflora, the notion of modifying the composition of the bacterial load to improve human health has arisen. A signifi cant body of research now exists investigating the role of probiotics and prebiotics in ameliorating chronic intestinal inflammation. This article will begin with an overview of the role of the commensal microflora in maintaining mucosal immune homeostasis, and how a dysregulated immune response to the intestinal microflora results in IBD. This will be followed by a summary of the use of probiotics and prebiotics in experimental and human IBD.

Preventative effects of a probiotic, Lactobacillus salivarius ssp. salivarius, in the TNBS model of rat colitis

AIM： To investigate the intestinal anti-inflammatory effect and mechanism of a probiotic Lactobacillus salivarius ssp. salivariusCECT5713 in the TNBS model of rat colitis. METHODS： Female Wistar rats （180-200 g） were used in this study. A group of rats were administered orally the probiotic L. salivarius ssp. salivarius （5 × 10^8 CFU suspended in 0.5 mL of skimmed milk） daily for 3 wk. Two additional groups were used for reference, a non-colitic and a control colitic without probiotic treatment, which received orally the vehicle used to administer the probiotic. Two weeks after starting the experiment, the rats were rendered colitic by intracolonic administration of 10 mg of TNBS dissolved in 0.25 mL of 500 mL/L ethanol. One week after colitis induction, all animals were killed and colonic damage was evaluated both histologically and biochemically. The biochemical studies performed in colonic homogenates include determination of myeloperoxidase （MPO） activity, glutathione （GSH） content, leukotriene B4 （LTB4） and tumor necrosis factor α （TNF-α） levels, as well as inducible nitric oxide synthase （iNOS） expression. In addition, the luminal contents obtained from colonic samples were used for microbiological studies, in order to determine Lactobacilli and Bifidobacteria counts. RESULTS： Treatment of colitic rats with L. salivarius ssp. salivarius resulted in amelioration of the inflammatory response in colitic rats, when compared with the corresponding control group without probiotic treatment. This antiinflammatory effect was evidenced macroscopically by a significant reduction in the extent of colonic necrosis and/or inflammation induced by the administration of TNBS/ethanol （2.3±0.4 cm vs3.4±0.3 cm in control group, P〈0.01） and histologically by improvement of the colonic architecture associated with a reduction in the neutrophil infiltrate in comparison with non-treated colitic rats. The latter was confirmed biochemically by a significant reduction of colonic MPO activity （105.3±26.0 U/g vs 180.6±21.9 U/g, P〈0.05）, a marker of neutrophil infiltration. The beneficial effect was associated with an increase of the colonic GSH content （1 252±42 nmol/g vs i 087±51 nmol/g, P〈0.05）, which is depleted in colitic rats, as a consequence of the oxidative stress induced by the inflammatory process. In addition, the treatment of colitic rats with L. salivarius resulted in a significant reduction of colonic TNF-（~ levels （509.4±68.2 pg/g vs782.9±60.1 pg/g, P〈0.01） and in a lower colonic iNOS expression, when compared to TNBS control animals without probiotic administration. Finally, treated colitic rats showed higher counts of Lactobacilli species in colonic contents than control colitic rats, whereas no differences were observed in Bifidobacteria counts. CONCLUSION： Administration of the probiotic L. salivarius ssp. salivarius CECT5713 facilitates the recovery of the inflamed tissue in the TNBS model of rat colitis, an effect associated with amelioration of the production of some of the mediators involved in the inflammatory response in the intestine, such as cytokines, including TNF-α and NO. This beneficial effect could be ascribed to its effect on the altered immune response that occurs in this inflammatory condition.

Effect of special Hungarian probiotic kefir on faecal microflora

AIM： To investigate the effect of a four-week consumption of a special Hungarian probiotic agent （Biofir） on the faecal microflora in human healthy subjects.METHODS： The effect of Biofir with 10^6/cm^3 initial germs on the faecal microflora was studied in 120 healthy volunteers （71 females, 49 males）. The traditional Russian type kefir was used as control. The various germ groups and pH values were determined in wk 2, 4 and 6.RESULTS： The number of all microbes increased during the 4-week probiotic treatment. The number of microbes increased 4,3-fold in the control group and 6.8-fold in Biofir-treated group. The probiotic kefir caused multiplication of the probiotic flora, meanwhile the undesired bacteria multiplied in the control group. No significant change of pH values of the faeces was found in both groups.CONCLUSION： The Hungarian probiotic keflr （Biofir） is capable of promoting multiplication of probiotic bacterial flora in the large bowel.