This Article Full Text Full Text (PDF) All Versions of this Article: 93/7/2819    most recent Author Manuscript (PDF) Submit a related Letter to the Editor Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Google Scholar Articles by Chan, J. L. Articles by Mantzoros, C. S. PubMed PubMed Citation Articles by Chan, J. L. Articles by Mantzoros, C. S. Pubmed/NCBI databases Gene GEO Profiles HomoloGene UniGene Substance via MeSH Related Collections Metabolism Neuroendocrinology and Pituitary

Leptin Does Not Mediate Short-Term Fasting-Induced Changes in Growth Hormone Pulsatility but Increases IGF-I in Leptin Deficiency States

Division of Endocrinology, Diabetes, and Metabolism (J.L.C., C.J.W., P.R., J.B., T.K., I.K., C.S.M.), Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215; and Division of Endocrinology and Metabolism (M.L.J., M.O.T.), University of Virginia Health System, Charlottesville, Virginia 22908

Address all correspondence and requests for reprints to: Christos S. Mantzoros, M.D., D.Sc., Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, ST 816, Boston, Massachusetts 02215. E-mail: cmantzor{at}bidmc.harvard.edu.

Context: States of acute and chronic energy deficit are characterized by increased GH secretion and decreased IGF-I levels.

Objective: The objective of the study was to determine whether changes in levels of leptin, a key mediator of the adaptation to starvation, regulate the GH-IGF system during energy deficit.

Design, Setting, Patients, and Intervention: We studied 14 healthy normal-weight men and women during three conditions: baseline fed and 72-h fasting (to induce hypoleptinemia) with administration of placebo or recombinant methionyl human leptin (r-metHuLeptin) (to reverse the fasting associated hypoleptinemia). We also studied eight normal-weight women with exercise-induced chronic energy deficit and hypothalamic amenorrhea at baseline and during 2–3 months of r-metHuLeptin treatment.

Main Outcome Measures: GH pulsatility, IGF levels, IGF and GH binding protein (GHBP) levels were measured.

Results: During short-term energy deficit, measures of GH pulsatility and disorderliness and levels of IGF binding protein (IGFBP)-1 increased, whereas leptin, insulin, IGF-I (total and free), IGFBP-4, IGFBP-6, and GHBP decreased; r-metHuLeptin administration blunted the starvation-associated decrease of IGF-I. In chronic energy deficit, total and free IGF-I, IGFBP-6, and GHBP levels were lower, compared with euleptinemic controls; r-metHuLeptin administration had no major effect on GH pulsatility after 2 wk but increased total IGF-I levels and tended to increase free IGF-I and IGFBP-3 after 1 month.

Conclusions: The GH/IGF system changes associated with energy deficit are largely independent of leptin deficiency. During acute energy deficit, r-metHuLeptin administration in replacement doses blunts the starvation-induced decrease of IGF-I, but during chronic energy deficit, r-metHuLeptin administration increases IGF-I and tends to increase free IGF-I and IGFBP-3.