Bile Acids Increase Independently From Hypocaloric Restriction After Bariatric Surgery.

ABSTRACT

OBJECTIVES: To measure changes in the composition of serum bile acids (BA) and the expression of Takeda G-protein-coupled receptor 5 (TGR5) acutely after bariatric surgery or caloric restriction. SUMMARY BACKGROUND DATA Metabolic improvement after bariatric surgery occurs before substantial weight loss. BA are important metabolic regulators acting through the farnesoid X receptor and TGR5 receptor. The acute effects of surgery on BA and the TGR5 receptor in subcutaneous white adipose tissue (WAT) are unknown. METHODS: A total of 27 obese patients with type 2 diabetes mellitus were randomized to Roux-en-Y gastric bypass (RYGB) or to hypocaloric diet (HC diet) restriction (NCT 1882036). A cohort of obese patients with and without type 2 diabetes mellitus undergoing vertical sleeve gastrectomy was also recruited (n = 12) as a comparison. RESULTS: After vertical sleeve gastrectomy, the level of BA increased [total 1.17 ±â€Š1.56 µmol/L to 4.42 ±â€Š3.92 µmol/L (P = 0.005); conjugated BA levels increased from 0.99 ±â€Š1.42 µmol/L to 3.59 ±â€Š3.70 µmol/L (P = 0.01) and unconjugated BA levels increased from 0.18 ±â€Š0.24 µmol/L to 0.83 ±â€Š0.70 µmol/L (P = 0.009)]. With RYGB, there was a trend toward increased BA [total 1.37 ±â€Š0.97 µmol/L to 3.26 ±â€Š3.01 µmol/L (P = 0.07); conjugated 1.06 ±â€Š0.81 µmol/L to 2.99 ±â€Š3.02 µmol/L (P = 0.06)]. After HC diet, the level of unconjugated BA decreased [0.92 ±â€Š0.55 µmol/L to 0.32 ± 0.43 µmol/L (P = 0.05)]. The level of WAT TGR5 gene expression decreased after surgery, but not in HC diet. Protein levels did not change. CONCLUSIONS: The levels of serum BA increase after bariatric surgery independently from caloric restriction, whereas the level of WAT TGR5 protein is unaffected.