Stress-induced intestinal barrier dysfunction is exacerbated during diet-induced obesity.

Obesity and irritable bowel syndrome (IBS) are two major public health issues. Interestingly previous data report a marked increase of IBS prevalence in morbid obese subjects compared with non-obese subjects but underlying mechanisms remain unknown. Obesity and IBS share common intestinal pathophysiological mechanisms such as gut dysbiosis, intestinal hyperpermeability and low-grade inflammatory response. We thus aimed to evaluate the link between obesity and IBS using different animal models. Male C57Bl/6 mice received high fat diet (HFD) for 12 weeks and were then submitted to water avoidance stress (WAS). In response to WAS, HFD mice exhibited higher intestinal permeability and plasma corticosterone concentration than non-obese mice. We were not able to reproduce a similar response both in ob/ob mice and in leptin-treated non-obese mice. In addition, metformin, a hypoglycemic agent, limited fasting glycaemia both in unstressed and WAS diet-induced obese mice but only partially restored colonic permeability in unstressed HFD mice. Metformin failed to improve intestinal permeability in WAS HFD mice. Finally, cecal microbiota transplantation from HFD mice in antibiotics-treated recipient mice did not reproduce the effects observed in stressed HFD mice. In conclusion, stress induced a more marked intestinal barrier dysfunction in diet-induced obese mice compared with non-obese mice that seems to be independent of leptin, glycaemia and gut microbiota. These data should be further confirmed and the role of the dietary composition should be studied.