Early changes in ghrelin following Roux-en-Y gastric bypass: influence of vagal nerve functionality?

Roux-en-Y gastric bypass (RYGBP) effectively produces massive weight reduction, improving health in morbidly obese patients. The mechanisms for the weight loss, and the fate of the excluded gastric mucosa, are not fully clarified. To what extent the appetite-stimulating gastric peptide ghrelin is affected remains controversial.

Circulating concentrations of ghrelin, pancreatic polypeptide (PP), pepsinogen I (PGI) and gastrin were examined in 15 morbidly obese patients (median BMI 45 kg/m2) preoperatively, and on days 1, 2, 4, 6 and at months 1, 6 and 12 after RYGBP.

Ghrelin levels fell on postoperative day 1 and increased after 1 month to preoperative levels, and rose further at 6 and 12 months. PP concentrations decreased on day 1 and subsequently returned to preoperative levels. PGI levels peaked transiently the first days after surgery and subsequently declined to lower than preoperative levels. Gastrin levels were gradually reduced postoperatively.

Ghrelin and PP fall transiently after surgery, possibly due to vagal dysfunction, and ultimately, as weight loss ensues, ghrelin secretion increases to higher than preoperative levels. The RYBGP procedure affects the gastric mucosa, as reflected by a transient increase in circulating PGI, and subsequently, the mucosa in the excluded stomach is at rest, as shown by low levels of PGI and gastrin.