title: Sex differences in gut fermentation and immune parameters in rats fed an oligofructose-supplemented diet.
abstract: BACKGROUND
  Mechanistic data to support health claims is often generated using rodent models, and the influence of prebiotic supplementation has largely been evaluated using male rodents. Given that sex-based differences in immune parameters are well recognized and recent evidence suggests differences in microbiota composition between sexes, validation of the effectiveness of prebiotics merits assessment in both males and females. Here, we have compared the effect of oligofructose (OF) supplementation on the fecal bacterial community, short chain fatty acid profiles, and gut mucosal and systemic immune parameters in male and female rats.
  
  
  METHODS
  Male and female rats were fed rodent chow or chow supplemented with OF (5 % w/w). Fecal community change was examined by analyzing 16S rRNA gene content. To compare effects of OF between sexes at the gut microbial and mucosal immune level, fecal short chain fatty acid and tissue cytokine profiles were measured. Serum lipopolysaccharide levels were also evaluated by the limulus amebocyte lysate assay as an indirect means of determining gut permeability between sexes.
  
  
  RESULTS
  In the fecal community of females, OF supplementation altered community structure by increasing abundance in the Phylum Bacteroidetes. In male rats, no changes in fecal community structure were observed, although fecal butyrate levels significantly increased. Liver Immunoglobulin A (IgA) levels were higher in males relative to females fed OF, and serum LPS concentrations were higher in males independent of diet. Females had higher basal levels of the regulatory cytokine interleukin-10 (IL-10) in the colon and liver, while males had higher basal levels of the pro-inflammatory cytokines IL-6 and cytokine-induced neutrophil chemoattractant-1 (CINC-1) in the cecum and liver.
  
  
  CONCLUSIONS
  We have shown that male and female rat gut communities metabolize an OF-supplemented diet differently. Sex-specific responses in both the fecal community and systemic immune parameters suggest that this difference may result from an increase in the availability of gut peptidyl-nitrogen in the males. These findings demonstrate the importance of performing sex-comparative studies when investigating potential health effects of prebiotics using rodent models.
authors.affiliation: Applied Bioscience Graduate Program and Faculty of Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, Ontario L1H 7K4 Canada.
authors.forename: Padmaja
authors.initials: P
authors.lastname: Shastri
authors.affiliation: Applied Bioscience Graduate Program and Faculty of Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, Ontario L1H 7K4 Canada.
authors.forename: Justin
authors.initials: J
authors.lastname: McCarville
authors.affiliation: Atlantic Food and Horticulture Research Center, Agriculture and Agri-Food Canada, Kentville, Nova Scotia B4N 1J5 Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Kalmokoff
authors.affiliation: Bureau of Nutritional Sciences, Health Canada, Ottawa, Ontario K1A 0K9 Canada.
authors.forename: Stephen P J
authors.initials: SP
authors.lastname: Brooks
authors.affiliation: Applied Bioscience Graduate Program and Faculty of Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, Ontario L1H 7K4 Canada.
authors.forename: Julia M
authors.identifier: 0000-0001-7207-2431
authors.initials: JM
authors.lastname: Green-Johnson
keywords: Butyrate; IgA; Liver; Microbiota; Oligofructose; Sex