Ultradian ghrelin pulsatility is disrupted in morbidly obese subjects after weight loss induced by malabsorptive bariatric surgery

Background: Suppression of ghrelin production after Roux-en-Y gastric bypass that suggested its contribution to appetite reduction has been reported. Objective: Because bitiopancreatic diversion (BPD) does not affect appetite, we compared ghrelin production and 24-h pulsatility between healthy control subjects and obese subjects before and after BPD. Design: A computerized algorithm identified peak heights, clearance rate, and peak frequency of ghrelin over 24 h. Twenty-four-hour energy expenditure was measured in the calorimetric chamber, and energy intakes were computed. Insulin sensitivity was measured with a euglycemic-hyperinsulinemic clamp. Results: Mean (+/- SD) 24-h plasma ghrelin concentrations were significantly (P < 0.0001) higher in control than in obese subjects (338.17 +/- 22.09 and 164.47 +/- 29.19 mu g/L, respectively), but they increased to 204.64 +/- 28.51 mu g/L in the obese subjects after BPD (P < 0.01). The pulsatility index was 0.098 +/- 0.016 and 0.041 +/- 0.014 mu g (.) L-1 (.) min(-1) in control and obese subjects, respectively (P < 0.01), and decreased to 0.025 +/- 0.007 mu g (.) 1(-1) (.) min(-1) after BPD (P < 0.05). Energy intakes before and after BFP did not differ significantly. Although metabolizable energy after BPD was 40% of the energy intake, that (per kg fat-free mass) after BPD did not different significantly from that before BPD. Conclusions: Weight loss induced by malabsorptive bariatric surgery is associated with greater ghrelin concentrations, which, however, remain consistently lower than those in control subjects, whereas ghrelin pulsatility is subverted. Higher ghrelin concentrations may contribute to the high calorie intakes observed in post-BPD subjects. The lack of normal pulsatility may explain the new impulse of these subjects to eat very frequently.