Abstract # 1854 Cohort differences in learning and memory in response to fiber feeding in genetically identical C57Bl/6J mice: A relationship to the gut microbiota?

Introduction Recent data indicates that environmental conditions early in life can alter behavioral outcomes and responses to dietary interventions in model experiments. The gut microbiota may mediate such differences. Methods Two cohorts, C1 ( n = 20) and C2 ( n = 20), of C57Bl/6J mice were randomized to a 5% pectin ( n = 20) or cellulose diet ( n = 20) for 16 weeks. Thereafter, learning and memory tests were conducted and distal colon contents were analyzed by 16S rRNA sequencing to measure compositional changes in the microbiota. Results In C1, pectin-fed mice displayed a higher percentage of time in target quadrant at the 24-h probe trial of the Morris Water Maze (MWM) versus cellulose-fed mice (p = 0.01). In C2, however, no effect of pectin was observed at the 24-h probe of MWM (p = 0.88). In both cohorts, UniFrac distance revealed a significant shift in the community structure of the microbiota by pectin feeding ( p < 0.01). However, UniFrac also revealed vastly different bacterial communities between cohorts ( p < 0.01). Further analysis revealed the microbial genus, Oscillospira, was significantly higher in C2 versus C1, and positively associated with distance from the platform during the 24-h probe test ( p < 0.05). This genus, which was also significantly reduced by pectin feeding in C1 but not C2, is strongly associated with gut permeability and inflammation. Conclusions Cohort differences in the microbiome may play a pivotal role in host behavior after a dietary intervention.