Leptin Does Not Directly Regulate the Pancreatic Hormones Amylin and Pancreatic Polypeptide
Interventional studies in humans
- Janice J. Hwang, MD1,
- Jean L. Chan, MD1,
- Georgia Ntali, MD2,
- Dalia Malkova, PHD3 and
- Christos S. Mantzoros, MD, DSC1
- 1Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
- 2Department of Nutrition and Dietetics, Harokopio University, Athens, Greece
- 3Division of Developmental Medicine, Glasgow University, Glasgow, Scotland, U.K
- Corresponding author: Dr. Christos Mantzoros, Division of Endocrinology, Diabetes, and Metabolism, 330 Brookline Ave., ST 816, Boston, MA 02215. E-mail: cmantzor{at}bidmc.harvard.edu
Abstract
OBJECTIVE—Leptin and the pancreatic hormones amylin and pancreatic polypeptide are being evaluated alone or in combination for the treatment of obesity, but their physiological regulation has not yet been fully elucidated. Thus, we examined whether amylin and pancreatic polypeptide are regulated by caloric intake and/or short- and long-term energy deprivation and whether any potential regulation is mediated by changes in leptin levels.
RESEARCH DESIGN AND METHODS—We measured circulating levels of amylin and pancreatic polypeptide after 1) a 75-g glucose load in 28 healthy, normal-weight women, 2) 72-h complete energy deficiency (severe hypoleptinemia) with administration of either placebo or replacement-dose recombinant methionyl human leptin (r-metHuLeptin) in normal-weight men (n = 6) and women (n = 7), and 3) chronic mild energy deficiency (mild hypoleptinemia) in 7 women with hypothalamic amenorrhea before and after r-metHuLeptin administration for 3 months.
RESULTS—Amylin and pancreatic polypeptide levels increased 15 min after a 75-g glucose load and remained elevated at 60 and 120 min (P < 0.0001). Fasting for 72 h decreased leptin (to 21%) and amylin (to 67%) of baseline but not pancreatic polypeptide levels. Normalizing leptin levels with r-metHuLeptin did not alter the fasting-induced decrease in amylin and had no effect on pancreatic polypeptide levels. Neither amylin nor pancreatic polypeptide levels were different in leptin-deficient women with hypothalamic amenorrhea compared with weight-matched control subjects, and normalization of leptin levels with r-metHuLeptin treatment did not alter amylin or pancreatic polypeptide levels.
CONCLUSIONS—Circulating amylin levels increase after a glucose load and decrease in response to short-term complete fasting, but these changes are not mediated by leptin.
- AUC, area under the curve
- BIDMC, Beth Israel Deaconess Medical Center
- GCRC, General Clinical Research Center
- OGTT, oral glucose tolerance test
- r-metHuLeptin, recombinant methionyl human leptin
Footnotes
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Published ahead of print at http://care.diabetesjournals.org on 5 February 2008. DOI: 10.2337/dc07-2433.
J.J.H. and J.L.C. contributed equally to this work.
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.
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- Accepted January 20, 2008.
- Received December 21, 2007.
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