Extra-adipocyte leptin release in human obesity and its relation to sympathoadrenal function

Nina Eikelis, Gavin Lambert, Glen Wiesner, David Kaye, Markus Schlaich, Margaret Morris, Jacqueline Hastings, Florentia Socratous, Murray Esler

Research output: Contribution to journalArticlepeer-review

57 Citations (Scopus)

Abstract

The link between the human sympathoadrenalmedullary system and the adipocyte hormone leptin is controversial. We measured total and regional norepinephrine spillover, epinephrine secretion rate, and extra-adipocyte leptin release in 22 lean [body mass index (BMI) <26] and 20 obese (BMI >28) normotensive men who underwent arterial and central venous catheterization. Because plasma clearance of leptin is primarily by renal removal, for men at steady state we could estimate whole body leptin release to plasma from renal plasma leptin extraction. Whole body leptin release was 1,950 ± 643 (means ± SE) ng/min in obese men and 382 ± 124 ng/ min in lean men (P < 0.05). Total and renal norepinephrine spillover rates correlated directly with whole body leptin secretion rate. Leptin is released from multiple nonadipocyte sites, which we tested by use of simultaneous arteriovenous blood sampling. We found a surprisingly large contribution of brain leptin release to the plasma leptin pool, 529 ± 175 ng/min (>40% whole body leptin release), with greater leptin release in obese than in lean men, 935 ± 321 vs. 160 ± 59 ng/min (P = 0.045). In parallel with leptin measurements, we also quantified brain serotonin turnover and jugular overflow of neuropeptide Y (NPY). Brain serotonin turnover was higher in obese than in lean men, 227 ± 112 vs. 21 ± 14 ng/min (P = 0.019), as was overflow of NPY from the brain, 12.9 ± 1.4 vs. 5.3 ± 2.2 ng/min (P = 0.042). These results suggest that leptin is released within the brain and at an increased rate in obese humans, in whom activation of brain serotonergic and NPY mechanisms also exists.

Original languageEnglish
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume286
Issue number5 49-5
DOIs
Publication statusPublished - May 2004
Externally publishedYes

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