Background: Clinical studies have shown similar rapid improvements in body mass and glycemic control after Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG). Evidence suggests that adaptive intestinal tissue growth and reprogramming of intestinal glucose disposal play a key role in the beneficial effects on glucose homeostasis after RYGB, but it is not known whether such adaptive changes also occur after sleeve gastrectomy.
Methods: High-fat diet-induced obese rats were subjected to either VSG or RYGB, and intestinal growth and functional adaptations were assessed by using morphometric, immunohistochemical, and immuno-blot techniques, 3 months after surgery or sham surgery.
Results: The cross-sectional areas of the Roux and common limbs are significantly increased after RYGB compared with sham surgery (Roux limb: 17.1 ± 4.0 vs. 5.5 ± 0.1 mm(2); common limb: 11.7 ± 0.6 vs. 5.1 ± 0.5 mm(2); p < 0.01), but the cross-sectional area of the corresponding jejunum is not different from controls after VSG. Similarly, mucosal thickness and the number of GLP-1 cells are not increased after VSG. Protein expression of hexokinase II is increased fourfold (p < 0.01) in the Roux limb after RYGB, but not in the jejunum after VSG.
Conclusions: Adaptive hypertrophy and reprogramming of glucose metabolism in the small intestine are not necessary for VSG to improve body composition and glycemic control. The similar beneficial effects of VSG and RYGB on glucose homeostasis might be mediated by different mechanisms.