Abstract
The influence of diet and exercise on intestinal mucus and the spatial organisation of the microbiota is poorly understood. Though, it has been observed that the spatial organisation of the microbiota can be altered extensively in Crohn’s disease and ulcerative colitis. This study aims to investigate the pathophysiological events in mouse colon that are associated with a high fat diet and lack of exercise. Forty-eight, 6-week old C57BL/6NTac male and female mice were fed a normal or high-fat diet for 12 weeks and randomly assigned to free wheel running or sedentary groups. After 12 weeks, animals were sacrificed and distal colon tissue sections with and without faecal material were fixed for histomorphometric analysis, immunohistochemistry for cyclooxygenase-2 and mucin-2, or fluorescent in situ hybridization with the universal bacterial probe EUB338 (5’-GCTGCCTCCCGTAGGAGT-3’). Goblet cell counts and distance between the microbiota and epithelial surface were determined using ImageJ software. All mice had a normal colon morphology except for high-fat fed female mice who ran, demonstrating a reduction of goblet cells that approached significance and a reduced mucin-2 expression. Voluntary wheel running attenuated high-fat diet induced COX-2 expression in female mice only. The distance between the microbiota and epithelial surface remained the same. Taken together, these results show that voluntary wheel running protect against high-fat diet-induced inflammation in the distal colon of female mice and responses to changes in host behaviour may differ between sex.