Fructo-oligosaccharide intensifies visceral hypersensitivity and intestinal inflammation in a stress-induced irritable bowel syndrome mouse model.

AIM

To determine whether fructo-oligosaccharide (FOS) affects visceral sensitivity, inflammation, and production of intestinal short-chain fatty acids (SCFA) in an irritable bowel syndrome (IBS) mouse model.

METHODS

Mice were randomly assigned to daily oral gavage of saline solution with or without FOS (8 g/kg body weight) for 14 d. Mice were further assigned to receive either daily one-hour water avoidance stress (WAS) or sham-WAS for the first 10 d. After 2 wk, visceral sensitivity was measured by abdominal withdrawal reflex in response to colorectal distension and mucosal inflammation was evaluated. Gas chromatography, real-time reverse transcription PCR, and immunohistochemistry assays were used to quantify cecal concentrations of SCFA, intestinal cytokine expression, and number of intestinal mast cells per high-power field (HPF), respectively.

RESULTS

Mice subjected to WAS exhibited visceral hypersensitivity and low-grade inflammation. Among mice subjected to WAS, FOS increased visceral hypersensitivity and led to higher cecal concentrations of acetic acid (2.49 ± 0.63 mmol/L 1.49 ± 0.72 mmol/L, < 0.05), propionic acid (0.48 ± 0.09 mmol/L 0.36 ± 0.05 mmol/L, < 0.01), butyric acid (0.28 ± 0.09 mmol/L 0.19 ± 0.003 mmol/L, < 0.05), as well as total SCFA (3.62 ± 0.87 mmol/L 2.27 ± 0.75 mmol/L, < 0.01) compared to saline administration. FOS also increased ileal interleukin (IL)-23 mRNA (4.71 ± 4.16 1.00 ± 0.99, < 0.05) and colonic IL-1β mRNA (2.15 ± 1.68 0.88 ± 0.53, < 0.05) expressions as well as increased mean mast cell counts in the ileum (12.3 ± 2.6 per HPF 8.3 ± 3.6 per HPF, < 0.05) and colon (6.3 ± 3.2 per HPF 3.4 ± 1.2 per HPF, < 0.05) compared to saline administration in mice subjected to WAS. No difference in visceral sensitivity, intestinal inflammation, or cecal SCFA levels was detected with or without FOS administration in mice subjected to sham-WAS.

CONCLUSION

FOS administration intensifies visceral hypersensitivity and gut inflammation in stress-induced IBS mice, but not in the control mice, and is also associated with increased intestinal SCFA production.