The influence of high fat diet on plasma incretins and insulin concentrations in Sprague-Dawley rats with diet-induced obesity and glucose intolerance undergoing ileal transposition

Background: The benefits of IT surgery are based on incretin effects. In this study we show the influence of high fat diet (HFD) used both before and after surgery, on ileal transposition (IT) effects. Methods: Forty-eight male rats were assigned to two groups: HFD and control diet (CD) fed rats. After eight weeks, HFD and CD fed rats were randomly assigned to two types of surgery: IT and SHAM, then for 50% of animals of each group the diet was changed, whereas the other 50% received the same type of diet. Eight weeks after surgery the incretin level, glucose tolerance as well as body mass and insulin level were assessed. Results: GLP-1 plasma concentration was significantly higher in the IT operated CD/CD group compared to fasting state and did not differ significantly from the SHAM operated CD/CD animals. IT influenced the glucose stimulated PYY plasma level when compared with SHAM operated animals in the CD/HFD group, where the PYY plasma level was higher than in the SHAM operated animals. The effect of IT as well as of pre and postoperative diet on GIP plasma levels were insignificant. The IT group members maintained on the CD were characterised by a lower fasting glucose level, both pre and postoperatively, compared with the SHAM operated animals. The effect of IT on the fasting glucose level in groups preoperatively maintained on an HFD was insignificant. Conclusions: IT surgery itself seems to have rather limited incretin effects in rats, whose obesity is the result of HFD.