LAUSR

Objectives Cholecystectomy (XGB), removal of the gallbladder, is the most common abdominal surgery performed in the United States. Individuals can survive without a gallbladder, but have an increased prevalence of gastrointestinal (GI) cancers and small intestinal bacterial overgrowth. However, little is known about the impact of XGB on the composition and functional capacity of the GI microbiota. We hypothesized that constant flow of bile in the GI tract following XGB would alter the microbiota community. We developed a model of XGB in ovariectomized (OVX) mice because the main XGB risk factors, age (40-50 yr) and sex (female), correspond with the onset of menopause. Additionally, psyllium husk (PH) fiber possesses strong bile acid (BA)-binding capacity. Thus, the objectives of this study were to assess the impact of XGB on the composition and functional capacity of the GI microbiota, and the ability of post-prandial PH intervention to curb these effects in XGB/OVX mice. Methods Twelve-wk-old female C57BL/6 J mice (N = 48) were fed a high-fat (45% kcal) diet for the entire study (16 wk). Ad libitum access to food was provided 15 hr/d. A 2x2 (surgery x diet) factorial design was used, resulting in four groups. XGB and sham (SHM) operations were performed at wk 0 and all mice were OVX at wk 4. SHM/FS and XGB/FS mice were fasted (FS) the remaining 9 hr/d while SHM/PH and XGB/PH mice had ad libitum access to PH pellets. Fresh fecal samples were collected throughout and cecal digesta was collected at sacrifice for microbiota composition and functional capacity using 16S rDNA sequencing and targeted qPCR, respectively. Results Cecal alpha diversity was greater in the XGB/PH group compared to both SHM groups (P < 0.01). Cecal Lactobacillus relative abundance was lower in PH mice compared to FS (P < 0.01). Relative abundance of cecal Lactococcus and Streptococcus were greater in XGB mice compared to SHM (P = 0.01, P = 0.02). Erysipelotrichaceae relative abundance was lower in XGB mice compared to SHM. At wk 16, PH mice had a greater reduction from baseline in fecal Akkermansia relative abundance compared to FS (P = 0.04). Conclusions XGB and post-prandial PH consumption increase GI microbiota species richness and alter several abundant taxa. Funding Sources University of Illinois Division of Nutritional Sciences Vision 20/20 grant program.