Background

We previously demonstrated effects of the biliopancreatic diversion with duodenal switch (BPD-DS) on the gut microbiota in Wistar rats fed a standard chow diet. In this study, we investigated the link between the changes induced by malabsorptive surgeries on the gut microbiota and the benefits of the surgeries on weight and fat mass, energy balance and glucose metabolism in rats rendered obese by high-fat feeding.

Methods

Sleeve gastrectomy (SG), Roux-en-y gastric bypass (RYGB), BPD-DS and single anastomosis duodeno-ileal bypass (SADI) were performed in Wistar rats fed a high-fat diet. Body weight and energy intake were measured daily during the eight weeks of the study. Glucose and insulin tolerance tests were performed on the fifth and sixth week post-surgery. Glucagon-like peptide 1 (GLP-1), peptide tyrosine tyrosine (PYY), insulin and glucose were measured at the eighth week post-surgery. Fecal samples were collected prior to surgery and 2 and 8 weeks after surgery. Fecal samples were analyzed by 16S rRNA gene high-throughput sequencing. Short-chain fatty acids were measured in feces collected prior to surgery and 3 and 8 weeks after surgery.

Results

Compared to SHAM and SG, RYGB, BPD-DS and SADI achieved lower weight gain, reduced body fat and improved glucose metabolism. 16S rRNA gene-based analysis of faeces revealed alterations of the microbiota such a decrease in bacterial richness and diversity at 2 and 8 weeks in RYGB, BPD/DS and SADI that were associated with increased proportions of Enterobacteriales and reduced Clostridiales. Moreover, the altered gut microbiota was linked with a shift in the production of short-chain fatty acids such as increased butyrate and propionate but reduced acetate in RYGB, BPD-DS and SADI groups. The increase in butyrate and propionate correlated well with the increase in PYY levels.

Conclusions

Our results revealed positive metabolic outcomes of malabsorptive surgeries in rats that are associated with changes in gut microbiota composition and function.