Different Effects of Vertical Banded Gastroplasty and Roux-en-Y Gastric Bypass on Meal Inhibition of Ghrelin Secretion in Morbidly Obese Patients

Abstract

A decrease in ghrelin plasma levels in morbidly obese patients subjected to bariatric surgery has been considered to help increase body weight loss. Contradictory results have been described after Roux-en-Y gastric bypass (RYGBP), and no study to date has compared RYGBP and vertical banded gastroplasty (VBG), the two main operations performed in the United States. We investigated the effects of RYGBP (10 patients) and VBG (12 patients) on basal and postmeal ghrelin plasma levels in 22 morbidly obese patients (20 F and 2 M), mean age 42.1 ± 3.7 years, mean weight 115 ± 3.9 kg, mean body mass index (BMI) 43.5 ± 1.7. Before surgery and after a 20% reduction in BMI, ghrelin concentrations (pg/mL; radioimmunoassay [RIA], DRG Diagnostics, Germany) were measured in all patients 45 min before and for 3 h after a standard liquid meal (Osmolite RTH solution, 500 mL, 504 kcal). The results were expressed as mean ± SD. Differences between times and groups were evaluated by Student's t-test and one-way analysis of variance (ANOVA). We found that basal ghrelin plasma levels were reduced after RYGBP (to 73.1 ± 6 pg/mL, p <. 05) but increased after VBG (to 172 ± 26 pg/mL, p <. 0009). After a standard liquid meal, ghrelin plasma levels decreased significantly over 1 h in VBG patients, whereas they remained unchanged in RYGBP patients. Since these results were obtained under the same metabolic and anthropometric conditions, we conclude that RYGBP acts through permanent inhibition of ghrelin secretion, whereas VBG merely restores the mechanisms of ghrelin regulation by nutrients.

KEYWORDS:

• bariatric surgery
• gastric by-pass
• ghrelin
• obesity
• vertical banded gastroplasty