Biliopancreatic diversion in rats is associated with intestinal hypertrophy and with increased GLP-1, GLP-2 and PYY levels

Background: Factors leading to weight loss and weight stabilization after bariatric surgery are not fully understood. The aims of this study were to develop an animal model for bilicipancreatic diversion (BPD) and to determine changes in gut hormones, malabsorption and small bowel histology postoperatively. Methods: 2 groups of Wistar rats underwent sham and BPD surgery. Daily postoperative weights and food intake were measured. 24-hour fecal collections were performed at Day 6 and 21. Bomb calorimetry was performed to determine the fecal calorific values. At day 23, levels of peptide YY (PYY), glucagon-like peptide 1 (GLP-1) and glucagon-like peptide 2 (GLP-2) were determined and small bowel biopsies were taken. Results: Animals in the BPD group had significant reduction in weight (P < 0.001) and in food intake (P<0.001) compared to the sham group. Serum levels of PYY, GLP-1 and GLP-2 in the BPD group were significantly higher (P < 0.005). Animals in the BPD group had significantly higher fecal energy content at Day 6 (P < 0.001) but not at Day 21 when compared to the sham group. Small bowel histology confirmed the presence of significantly increased mitosis (P=0.03) and labelled cells (P=0.002) in the BPD animals when compared to sham. Conclusions: In our animal model, the higher levels of PYY, GLP-1 and GLP-2 after BPD may be due to gut adaptation and hypertrophy and could be important in inducing and maintaining weight loss after bariatric surgery.