Although hibernating mammals wake occasionally to eat during torpor, this period represents a state of fasting. Fasting is known to alter the gut microbiota in nonhibernating mammals; therefore, hibernation may also affect the gut microbiota. However, there are few reports of gut microbiota in hibernating mammals. The present study aimed to compare the gut microbiota in hibernating torpid Syrian hamsters with that in active counterparts by using culture-independent analyses. Hamsters were allocated to either torpid, fed active, or fasted active groups. Hibernation was successfully induced by maintaining darkness at 4°C. Flow cytometry analysis of cecal bacteria showed that 96-h fasting reduced the total gut bacteria. This period of fasting also reduced the concentrations of short chain fatty acids in the cecal contents. In contrast, total bacterial numbers and concentrations of short chain fatty acids were unaffected by hibernation. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments indicated that fasting and hibernation modulated the cecal microbiota. Analysis of 16S rRNA clone library and species-specific real-time quantitative PCR showed that the class Clostridia predominated in both active and torpid hamsters and that populations of Akkermansia muciniphila, a mucin degrader, were increased by fasting but not by hibernation. From these results, we conclude that the gut microbiota responds differently to fasting and hibernation in Syrian hamsters.

The effects of mushroom fibers on serum cholesterol and hepatic low-density lipoprotein (LDL) receptor mRNA in rats were investigated. Rats were fed a cholesterol-free diet with 50 g/kg cellulose powder (CP), 50 glkg maitake (Grifo/a frondosa) fiber (MAF), 50 glkg shiitake (Lentinus edodes) fiber (SF), or 50 g/kg e,. _ldtake (F/ammulina ve/utipes) fiber (EF) for 4 weeks. There were no significant differences in the body weight, food intake, liver weight, cecum weight, and cecum pH among the groups. Cecal acetic acid, butyric acid, and total short-chain fatty acid (SCFA) concentrations in the SF and EF groups were significantly higher than those in the other groups. The serum total cholesterol concentration in the CP group was significantly higher than that in the MAF and EF groups. The very LDL (VLDL) + Intermediate-density lipoprotein (IOl) + lOl-cholesterol concentration in the CP group was significantly higher than that in the MAF, SF, and EF groups, whereas the high-density lipoprotein (HOl)-cholesterol concentration in the EF group was significantly lower than that in the other groups at the end of the 4-week feeding period. The hepatic LDL receptor mRNA level in the EF group was significantly higher than that in the CP group. The fecal cholesterol excretion in the MAF, SF, and EF groups was significantly higher than that In the CP group. The results of this study demonstrate that MAF and EF lowered the serum total cholesterol level by enhancement of fecal cholesterol excretion, and in particular, by enhancement of hepatic LDL receptor mRNA In EF group.

Because gut microbiota has recently attracted much attention as an environmental factor involved in the development of obesity, probiotics may be useful in preventing and/or improving obesity and its related disorders. The present study aimed to investigate the effects of Lactobacillus plantarum strain No. 14 (LP14), a bacterial strain reported to decrease body fat percentage in healthy volunteers, on adipocyte size in mice. Female C57BL/6 mice were fed either normal- or high-fat diet and administered intragastrically with LP14 (1 x 10(8) colony-forming units/mouse) or vehicle daily for 11 weeks. High dietary fat intake increased body weight gain, white adipose tissue weight, mean adipocyte size and serum total cholesterol and leptin concentrations, and decreased serum adiponectin concentration. In mice fed the high-fat diet, LP14 administration significantly reduced the mean adipocyte size and tended to reduce the white adipose tissue weight and serum total cholesterol and leptin concentrations as compared with the vehicle-administered mice. All mice had undetectable serum levels of conjugated linoleic acids that reportedly exert antiobesity action. In a separate experiment, LP14 ingestion had no influence on serum triacylglycerol accumulation following olive oil administration in Triton WR1339-treated mice, suggesting that dietary fat absorption is unaffected by LP14. In conclusion, we propose that LP14 may exert a beneficial effect on the onset of diet-induced obesity by reducing the cell size of white adipose tissues, and it seems unlikely that previously reported mechanisms for other bacterial strains are involved in the action of LP14.

It has been difficult to produce persistent colonization by Candida albicans in the gastrointestinal tract of adult mice without the use of antibiotics and immunosuppressants. We hypothesized that diet influences the colonization of C. albicans and tested the hypothesis. BALB/c mice fed either a commercial rodent diet or a nutritionally adequate mixture of purified ingredients were inoculated i.g. with C. albicans (5 x 10(7) cells). Gastrointestinal colonization was examined by fecal culture, tissue culture, and histology. Mice fed the purified diet had a high fecal recovery of C. albicans [5-6log(10) colony forming units (cfu)/g feces] throughout the experimental period (6 wk), and the major site of colonization was the stomach. C. albicans was undetectable in the feces of mice fed the commercial diet 2 wk after inoculation. Immunosuppressants induced systemic dissemination of C. albicans in mice fed the purified diet. The number of lactobacilli and the concentration of organic acids in the stomach were significantly lower in mice fed the purified diet than in those fed the commercial diet. In vitro culture experiments revealed that acetic and lactic acids suppressed the growth of C. albicans. These results suggest that a reduction in lactobacilli in the stomach of mice fed the purified diet contributed to sustained gastric candidiasis. We therefore propose a novel model of sustained gastric candidiasis by a single i.g. inoculation of C. albicans in healthy adult mice fed a purified diet.

This study examined the role of degree of polymerization (DP) of inulin-fructans in modulating the interaction between lactic acid bacteria and IgA cecal secretion. Rats were fed a control diet or a diet containing one of the fructans with different DP. Consuming fructans increased the cecal IgA concentrations in the order DP4 > DP8 > DP16. Cecal lactobacilli counts were higher in DP4, DP8, and DP16, whereas bifidobacteria were higher in DP8, DP16, and DP23. Cecal IgA concentrations were correlated with cecal lactobacilli counts (P < 0.01). DP4, DP8, and DP16, but not DP23, significantly increased IgA-producing plasma cells in the cecal mucosa. IFN-γ and IL-10 production in the cecal CD4(+) T cells was enhanced solely in DP4. The results show that fructans with lower DP enhance cecal IgA secretion and increase the plasma cells and suggest that the increased lactobacilli may contribute to the stimulation of cecal IgA secretion.

Plasma cholesterol concentration is reduced by feeding some dietary fibers and mushroom fruit body, but the mechanism is not fully understood. We examined the effects of mushroom (Agaricus bisporus) fiber and sugar beet fiber on serum cholesterol and hepatic LDL receptor mRNA in rats. Rats were fed a cholesterol-free diet with 50 g/kg cellulose powder (CP), 50 g/kg mushroom (Agaricus bisporus) fiber (MSF) or 50 g/kg sugar beet fiber (BF) for 4 wk. There were no significant differences in the body weight, food intake and cecum weight among the groups. The relative liver weight in the CP group was significantly greater than that in the MSF and BF groups. The cecal pH in the CP and MSF groups was significantly higher than that in the BF group. Cecal acetic acid, butyric acid and total short-chain fatty acid (SCFA) concentrations in the BF group were significantly higher than those in the other groups. The serum total cholesterol, VLDL + intermediate density lipoprotein (IDL) + LDL cholesterol concentrations in the CP group were significantly greater than those in the MSF and BF groups. The HDL cholesterol concentration in the MSF group was significantly lower than that in the CP group. The hepatic LDL receptor mRNA level in the MSF and BF groups was significantly higher than that in the CP group. The results of this study demonstrate that mushroom fiber and sugar beet fiber lowered the serum total cholesterol level by enhancement of the hepatic LDL receptor mRNA.

Previous studies suggest that adipocyte-derived exosomes play a role in cell-to-cell communication during the development of metabolic diseases. However, the characteristics and function of exosomes released from adipocytes in vivo remain to be elucidated. Clearly, exosomes released from adipocytes could exist in the circulation. In addition, because the composition of exosomes is heterogenic, depending on the cellular origin of the exosome, adipocyte-derived exosomes could be accompanied by molecules produced specifically in adipocytes. In this context, this study postulated that such molecules associated with exosomes in the serum could be markers for adipocyte-derived exosomes in vivo. This study particularly focused on secretory proteins produced specifically in adipocytes, namely adipocytokines including adiponectin, leptin, and resistin. Serum adiponectin is partially associated with exosomesBased on western blotting, CD63, a well-known protein marker of exosomes, was concentrated in the pellet of mouse serum after ultracentrifugation, suggesting successful isolation of exosomes. Western blotting detected adiponectin but no leptin and only trace amounts of resistin in the exosome fraction. After ultracentrifugation on a discontinuous gradient, both adiponectin and CD63 were detected in a fraction at a density of 1.17 g/mL, consistent with the density of exosomes. The adiponectin signal in the exosome fraction was decreased by proteinase K treatment and completely quenched by a combination of proteinase K and Triton X-100. These results suggest that a portion of adiponectin exists as a transmembrane protein in the exosomes in mouse serum. showed that the concentration of adiponectin in the serum and the ratio of adiponectin to total protein in the exosome fraction were lower in obese mice than in lean mice.In conclusion, this study showed that serum adiponectin is partially associated with exosomes in mice. Considering that adiponectin is produced exclusively by adipocytes, adiponectin-associated exosomes in serum could be derived from adipocytes. This study proposes that adiponectin could be a marker for exosomes released from adipocytes in vivo.iii

Strategies to manipulate the gut microbiota in infancy have been considered to prevent the development of allergic diseases later in life. We aimed to elucidate the effects of maternal dietary supplementation with a prebiotic oligosaccharide on gut microbiota and spontaneously developing atopic dermatitis-like skin lesions in the offspring of NC/Nga mice. Female NC/Nga mice were fed diets either with or without fructooligosaccharide supplementation during pregnancy and lactation. After weaning, offspring were fed the diets supplemented with or without fructo-oligosaccharide for 11 weeks in an air-uncontrolled conventional room. Changes in gut microbiota were assessed by denaturing gradient gel electrophoresis of the PCR-amplified 16S rRNA gene. Skin lesions were evaluated by a clinical score and scratching behaviour. Serum antibody levels were measured by ELISA, and expression levels of cytokines and chemokines in lesional tissue were evaluated by quantitative RT-PCR. Maternal supplementation with fructo-oligosaccharide modulated the gut microbiota in sucklings. Although maternal supplementation with fructo-oligosaccharide suppressed the increase in clinical skin severity score and scratching behaviour in offspring, dietary fructooligosaccharide after weaning was less effective. The diminution of skin lesions was accompanied by lower serum concentrations of total IgG1 and lower expression levels of TNF-a in the lesional tissue. These data suggest that maternal consumption of fructo-oligosaccharide diminishes the severity of atopic dermatitis-like skin lesions in the offspring of NC/Nga mice. Fructo-oligosaccharide: Prebiotics: Atopic dermatitis: Gut microbiota: NC/Nga miceThe gut microbiota play an important role in maintaining host health by preventing the colonisation of pathogens, degrading dietary compounds and maintaining normal mucosal immunity. Particularly, the composition of the gut microbiota early in life profoundly influences later immune responses (1 -4) . Therefore, strategies to manipulate the microbiota in infancy have been considered in preventing the onset of allergic diseases. This idea is supported by epidemiological data demonstrating that differences in the composition of gut microbiota in infancy precede the development of atopic dermatitis (AD) (5 -8) . In addition, clinical trials showed that maternal administration of Lactobacillus rhamnosus GG (i.e. probiotics) during pregnancy and lactation was beneficial in preventing the development of AD in at-risk children during the first 4 years of life (9,10) . However, L. rhamnosus GG administration did not benefit adolescents suffering from birch pollen allergy (11) . These findings suggest that the time point for exposure to probiotics is important in preventing the development of allergic diseases.Indigestible oligosaccharides are regarded as prebiotics that affect the host by selectively stimulating the growth and/or activity of beneficial bacteria such as bifidobacteria and lactobacilli in the intestinal tract, and thus improving host...