Effects of an enriched environment on the intestinal mucosal barrier and brain gut axis in colorectal cancer model rats

Abstract Objectives: Environmental enrichment (EE) involves introducing animals to novel, complex, and stimulating surroundings, which can protect the intestinal mucosal barrier and regulate brain–gut peptide expression. However, the effects of EE and a normal environment have not been compared in rats, and to what extent EE can protect the injured intestinal mucosal barrier is unknown. Herein, the effects of probiotics, EE, and joint intervention targeting the intestinal mucosal barrier and brain–gut axis were assessed in rats with colorectal cancer.Methods: Each rat was weighed, and rats were housed under four different conditions for 4 weeks: an enriched environment, colorectal cancer modeling, joint conditions and normal conditions. We used a rat model of 1,2-dimethylhydrazine (DMH)-induced colorectal cancer. The intestinal mucosal and serum levels of TNF-α, IL-6, IL-10, DAO, ATP, CRF, and occludin and bacterial translocation (BT) were measured, and the intestinal mucosal morphology was evaluated.Results: EE was beneficial for serum and intestinal mucosal cytokine, hypothalamic CRF, substance P, and occludin levels; villus length; and muscle thickness (P<0.05). There were no significant differences in villus width or BT between the enriched environment group and other groups (P>0.05).Conclusions: Colorectal cancer can damage the intestinal mucosa, but EE is conducive to protecting the intestinal mucosa in colorectal cancer and healthy conditions. EE is helpful in regulating brain–gut peptides. In future research, the effect of EE on the physical and biological barriers established by the intestinal mucosa and the mechanism of EE related to the intestinal mucosa should be explored.