Peptide YY Levels Are Elevated After Gastric Bypass Surgery

Authors

  • Jean L. Chan,

    1. Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
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  • Edward C. Mun,

    1. Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
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  • Violeta Stoyneva,

    1. Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
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  • Christos S. Mantzoros,

    1. Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
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  • Allison B. Goldfine

    Corresponding author
    1. Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
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  • The costs of publication of this article were defrayed, in part, by the payment of page charges. This article must, therefore, be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

Joslin Diabetes Center, One Joslin Place, Boston, MA 02115. E-mail: agoldfine@joslin.harvard.edu

Abstract

Objective: Mechanisms that promote effective and sustained weight loss in persons who have undergone Roux-en-Y gastric bypass surgery are incompletely understood but may be mediated, in part, by changes in appetite. Peptide YY (PYY) is a gut-derived hormone with anorectic properties. We sought to determine whether gastric bypass surgery alters PYY levels or response to glucose.

Research Methods and Procedures: PYY and ghrelin levels after a 75-gram oral glucose tolerance test were measured in 6 morbidly obese patients 1.5 ± 0.7 (SE) years after gastric bypass compared with 5 lean and 12 obese controls.

Results: After substantial body weight loss (36.8 ± 3.6%) induced by gastric bypass, the PYY response to an oral glucose tolerance test was significantly higher than in controls (p = 0.01). PYY increased ∼10-fold after a 75-gram glucose load to a peak of 303.0 ± 37.0 pg/mL at 30 minutes (p = 0.03) and remained significantly higher than fasting levels for all subsequent time-points. In contrast, PYY levels in obese and lean controls increased to a peak of ∼2-fold, which was only borderline significant. Ghrelin levels decreased in a symmetric but opposite fashion to that of PYY.

Discussion: Gastric bypass results in a more robust PYY response to caloric intake, which, in conjunction with decreased ghrelin levels, may contribute to the sustained efficacy of this procedure. The findings provide further evidence for a role of gut-derived hormones in mediating appetite changes after gastric bypass and support further efforts to determine whether PYY3–36 replacement could represent an effective therapy for obesity.

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