The post-prandial secretion of Peptide YY1-36 and 3-36 in obesity is differentially increased after gastric bypass versus sleeve gastrectomy

OBJECTIVES: Peptide tyrosine tyrosine (PYY) exists as two species, PYY1-36 and PYY3-36, with distinct effects on insulin secretion and appetite regulation. The detailed effects of bariatric surgery on PYY1-36 and PYY3-36 secretion are not known as previous studies have used non-specific immunoassays to measure total PYY. Our objective was to characterise the effect of sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) on fasting and post-prandial PYY1-36 and PYY3-36 secretion using a newly developed liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay. DESIGN AND SUBJECTS: Observational study in 10 healthy non-obese volunteers and 30 participants with obesity who underwent RYGB (n=24) or SG (n=6) at the Imperial Weight Centre [NCT01945840]. Participants were studied using a standardised mixed meal test (MMT) before and 1 year after surgery. The outcome measure was PYY1-36 and PYY3-36 concentration. RESULTS: Pre-surgery, the fasting and post-prandial levels of PYY1-36 and PYY3-36 were low, with minimal responses to the MMT, and these did not differ from healthy non-obese volunteers. The postprandial secretion of both PYY1-36 and PYY3-36 at 1 year was amplified after RYGB, but not SG, with the response being significantly higher in RYGB compared to SG. CONCLUSIONS: There appears to be no difference in PYY secretion between non-obese and obese volunteers at baseline. At 1 year after surgery, RYGB, but not SG, is associated with increased post-prandial secretion of PYY1-36 and PYY3-36, which may account for long-term differences in efficacy and adverse effects between the two types of surgery