Effects of Roux-en-Y Gastric Bypass Surgery on Fasting and Postprandial Concentrations of Plasma Ghrelin, Peptide YY, and Insulin

Abstract

To help understand the mechanisms by which weight loss is maintained after Roux-en-Y gastric bypass (RYGBP), we measured circulating concentrations of total and bioactive octanoylated ghrelin, peptide YY (PYY), glucose, and insulin in the fasted state and in response to a liquid test meal in three groups of adult women: lean (n = 8); weight-stable 35 +/- 5 months after RYGBP (n = 12; mean body mass index, 33 kg/m(2)); and matched to the surgical group for body mass index and age (n = 12). Fasting plasma total ghrelin levels were nearly identical between RYGBP (425 +/- 54 pg/ml) and the matched controls (424 +/- 28 pg/ml) and highest in lean controls (564 +/- 103 pg/ml). The response to the test meal was comparable between lean and RYGBP groups, with 27% and 20% maximal suppression, respectively, whereas the magnitude of suppression was significantly diminished in the matched controls (17%) compared with the lean group. Fasting levels of octanoylated ghrelin were highest in the lean controls, 220 +/- 36 pg/ml vs. 143 +/- 27 in the RYGBP group (P = 0.05) and 127 +/- 12 pg/ml in the matched controls (P < 0.05). The magnitude of maximal postmeal suppression of octanoylated ghrelin was more marked than with total ghrelin, but similar among groups, ranging from 44-47%. In response to the test meal, there was an early exaggerated rise in PYY in the RYGBP group, such that the peak PYY concentration was 163 +/- 24 pg/ml compared with 58 +/- 17 (P < 0.01) and 77 +/- 23 (P < 0.05) in the matched and lean controls, respectively; area under the curve at 90 min was significantly greater compared with both control groups. Leptin and fasting insulin concentrations and homeostasis model of assessment insulin resistance indices were nearly identical between lean and RYGBP subjects and significantly higher in the body mass index-matched controls. In summary, the absence of a compensatory increase in ghrelin concentrations that usually occurs with diet-induced weight loss, and the exaggerated postprandial PYY response after RYGBP, may contribute to weight loss and to the ability of an individual to maintain weight loss after this surgical procedure.

Meal suppression of circulating ghrelin is normalized in obese individuals following gastric bypass surgery

“…For all groups in the present study, the insulin levels following the meal were related to the degree of suppression of ghrelin secretion. The higher meal suppression of ghrelin in operated patients compared with BMImatched controls noted by Korner et al 31 is in agreement with our findings. Probably, the rapid increment and fast decline of insulin secretion in the operated patients are of importance for the decline in ghrelin levels postprandially.…”

“…An interesting finding in the present study was the high increment in glucose and insulin in the RYGBP group. This has been reported earlier 31 and is probably due to the fast passage of food through the gastric remnant into the intestine. For all groups in the present study, the insulin levels following the meal were related to the degree of suppression of ghrelin secretion.…”

“…18 On the other hand, one recent study reported a similar response to a test meal in lean and RYGBP groups and higher in operated patients than in BMI-matched controls. 31 They also found fasting plasma ghrelin levels nearly identical between RYGBP-and BMI-matched controls (BMI 33 kg/m 2 ). In the present cross-sectional study, we found higher fasting, morning ghrelin levels in the RYGBP group than in the age-matched morbidly obese, which is in accordance with our previous prospective study in 66 patients before and after gastric bypass.…”

Increase in Ghrelin Levels After Weight Loss in Obese Zucker Rats is Prevented by Gastric Banding

“…In humans, fasting and post-prandial plasma levels of PYY increase progressively 6 and 12 months after vertical banded gastroplasty surgery [46]. Some authors have found that the PYY area under the curve after a test meal was also superior in obese patients submitted to gastric banding when compared weight-matched obese controls [15], although in another similar study, this was not found to be the case [47]. Six months after vertical banded gastroplasty, fasting plasma GLP-1 concentrations did not change significantly, but the area under the curve during an oral glucose tolerance test strikingly increased [48].…”

Treatment of morbid obesity by intraparietogastric administration of botulinum toxin: a randomized, double-blind, controlled study

“…Vertical banded gastroplasty increases post-meal cholecystokinin plasma levels, 8 whereas Roux-en-Y gastric by-pass inhibits basal and post-prandial ghrelin plasma levels 9 and increases peptideYY (PYY) concentrations. 10 Jejuno-ileal by-pass increases cholecystokinin, motilin, glucagon-like peptide 1 and PYY, 11 delays gastric emptying and reduces hunger sensations. As cholecystokinin, ghrelin and PYY also influence gastrointestinal motility, it can be hypothesized that reduction of gastric emptying could contribute to the satiety effect of the operations.…”