Expression of ghrelin in fundus is increased after gastric banding in morbidly obese patients

Abstract

Ghrelin, a 28 amino-acid acylated orexigenic peptide secreted by the stomach, acts on the hypothalamic arcuate nucleus which stimulates feeding behavior. Serum ghrelin level increases during fasting and decreases after a meal. Serum ghrelin is low in obese patients.Whether ghrelin is implicated in weight loss in obese patients after laparoscopic adjustable gastric banding (LAGB) is still debated. In this study, we assessed serum ghrelin level and gastric fundus expression before and 1 year after LAGB. Gastric fundus expression of ghrelin was assessed by immunohistochemistry using a rabbit anti-human ghrelin antibody simultaneously with serum total ghrelin levels (RIA) in 13 obese patients (2 men and 11 women) after an overnight fast, before LAGB and 1 year after. Immunostaining was "blindly" analyzed by a single pathologist, measuring the density of stained fundic cells near muscularis mucosa. Mean age of the 13 patients was 41 years, and mean baseline BMI was 46 kg/m2. Pre- and post-LAGB gastric expression of ghrelin was analyzable in 11 patients. It was always identified, mostly with moderate or intense staining. Mean density of stained cells significantly increased 1 year after LAGB: 31/mm2 (21-38) before vs 38/mm2 (27-57) after surgery (P<0.01). This increase did not correlate with changes in BMI, nor did pre- or postoperative gastric expression of ghrelin correlate with the corresponding serum values. We showed for the first time that ghrelin expression assessed by immunohistochemistry was present in the fundus of all 11 obese patients and that it was significantly increased 1 year after LAGB, which would exclude a pathogenetic role of ghrelin in weight loss after LAGB.