Roux-en-Y gastric bypass with a long versus a short biliopancreatic limb improves weight loss and glycemic control in obese mice

Background: Roux-en-Y gastric bypass (RYGB) results in long-term weight loss and reduced obesity related co-morbidities. However, little is known about how the lengths of the biliopancreatic limb (BPL), the alimentary limb (AL), and the common limb (CL) affect weight loss and glucose metabolism.

Objectives: Our aim was to establish a RYGB obese mouse model with defined proportions of the AL and BPL and a constant CL to assess the effects on weight loss,glucose metabolism, and obesity-related co-morbidities.

Setting: In vivo mouse study.

Methods: Six-week-old male C57BL/6J mice fed with a high-fat diet (HFD) underwent bariatric surgery with defined BPL lengths: a very long, long, and short BPL (35%, 25%, and 15% of total bowel length), or sham surgery. The length of the AL was adjusted to achieve the same CL length. Mice were analyzed for weight loss, glycemic control, and obesity-related co-morbidities.

Results: Mice undergoing RYGB surgery with a very long BPL had excessive weight loss and mortality and were therefore not further analyzed. Mice with a long BPL showed a significantly increased total weight loss when compared with mice with a short BPL. In addition, a long BPL improved glucose tolerance, particularly early after surgery. A long BPL was also associated with lower triglyceride levels. Resolution of hepatic steatosis and adipose tissue inflammation was, however, not statistically significant. Of note, bariatric surgery dramatically changed gut microbiota, regardless of limb length.

Conclusion: In obese mice, a long BPL results in enhanced weight loss and improved glucose tolerance. These findings could potentially be translated to humans by tailoring the BPL length according to body weight, obesity-related co-morbidities, and total bowel length of an individual patient.