SPLTRAK Abstract Submission
Differential effects of a high fat/sucrose diet versus a low fat diet on glucose homeostasis and beta-cell sensitivity in a rat model of gastric bypass surgery
WARNER HOORNENBORG1, EDIT SOMOGYI1, JAN BRUGGINK1, THOMAS LUTZ2,3, CHRISTINA BOYLE2, MARLOES EMOUS4, ANDRE VAN BEEK5, GERTJAN VAN DIJK1
1University of Groningen, GELIFES Neurobiology, Groningen, Netherlands/2Vetsuisse Faculty University of Zurich, Zurich, Switzerland/3Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland/4Medical Center Leeuwarden, Department of Bariatric and Metabolic Surgery, Leeuwarden, Netherlands/5University Medical Center Groningen, Groningen, Netherlands
   Roux-en Y gastric bypass (RYGB) surgery is the only sustainable treatment of morbid obesity, not only for its weight reducing and hypophagic effects, but also for the marked improvements of metabolic co-morbidities. In fact, obese patients undergoing bariatric surgery frequently have remission of type-2 diabetes mellitus.  It is not clear whether and how the habitual diet affects behavioral and metabolic outcomes following RYGB.  For this reason, we investigated ingestive behavioral and glucose homeostasis parameters in 5 month-old male Wistar rats that were maintained chronically either on a low-fat chow diet (LF, n=6-8) or a high fat/sucrose chow diet (HFS, 6-11) in pelleted form, before and after RYGB.  While RYGB caused considerable weight loss over 4 weeks, this weight loss was most outspoken in the HFS group (-30% versus -20% in the LF group), with reduction in fat mass but not lean mass contributing to this phenomenon. Energy intake was most profoundly reduced by RYGB in the HFS group (-50%) relative to the LF group (-25%). Meal size, but not meal frequency or intermeal interval changed significantly by RYGB, with a significantly higher satiety ratio increase in the HFS feeding rats than found in the LF group.  Glucose homeostasis assessed at baseline (HOMA-IR) and assessed by a mixed meal tolerance test (MMT) showed improvements of insulin resistance and beta cell sensitivity irrespective of diet, however, rats on the HFS (but not on the LF diet) became glucose intolerant after RYGB surgery in the MMT test.  Our results show that post-RYGB glucose homeostasis in HFS feeding rats appeared deranged despite most profound reductions in weight loss and increased satiety.

Supported By: University Medical Center Groningen