The effects of moderate exercise on chronic stress-induced intestinal barrier dysfunction and antimicrobial defense

The purpose of this study was to examine the effect of moderate exercise on repeated restraint stress (RRS)-induced intestinal barrier dysfunction and explore possible mechanisms in a mouse model. Male Balb/c mice (6 weeks) were randomized into 7 groups: CON functioned as controls with no intervention; RRS was subjected to 6 h per day RRS for 7 consecutive days; RRS+SWIM received 30 min per day of swimming prior to RRS; CON+SWIM only received 30 min per day of swimming; and the other groups received one session of 30 min swimming prior to sacrifice at 1-, 3- and 6 h recovery. Intestinal permeability was quantified with FITC-dextran. Bacterial translocation was determined by quantification of bacterial colony forming units (CFUs) in cultured mesenteric lymph nodes (MLN), and with fluorescence in situ hybridization (FISH). Antimicrobial related gene expression at baseline and 1 h after one session of 30 min swimming was tested by quantitative real-time polymerase chain reaction (Q-PCR) in small intestinal segments. Protein expression of 5 genes with statistically significant increase was measured at baseline, and 1-, 3- and 6 h post-swimming using enzyme-linked immunosorbent assay (ELISA). Thirty minutes per day of swimming before RRS attenuated bacterial translocations and maintained intestinal permeability. Gene expression and protein levels for four antimicrobial peptides (α-defensin 5, β-defensin 1, RegIIIβ and RegIIIγ) were significantly increased after one 30 min swimming session. In conclusion, moderate exercise attenuated chronic stress-induced intestinal barrier dysfunction in mice, possibly due to augmentation of antimicrobial responses in the small intestine.