Hormonal regulation of human leptin in vivo: effects of hydrocortisone and insulin.
OBJECTIVE
To investigate the effects of continuous i.v. infusion of hydrocortisone or insulin on leptin secretion in humans.


METHODS
Six, nonfasting healthy adults (four women, two men), aged (mean +/- s.e.m.) 36.6 +/- 1.7 y; body mass index (BMI) 27.6 +/- 0.9 kg/m2.


METHODS
Randomized, placebo-controlled, cross-over study, with a 2-week 'wash-out' period.


METHODS
Intravenous infusion of hydrocortisone (3.3 microg/(kg min)), insulin (1 mU/(kg min)) or normal saline (placebo) for 24 h.


METHODS
Blood sampling every 1-2 h for measurement of glucose, insulin, cortisol and leptin; subcutaneous abdominal fat biopsy for determination of leptin mRNA expression.


RESULTS
Plasma cortisol increased to 50.0 +/- 0.4 microg/dl during hydrocortisone infusion, but was unaltered during saline or insulin infusion. The plasma insulin levels were: 28.5 +/- 4.7 microU/ml (placebo), 40.8 +/- 9.2 microU/ml (hydrocortisone, P=0.214), and 243 +/- 23.0 microU/ml (insulin, P=0.0002). Peak hyperleptinemia occurred after 16h of insulin and 20h of hydrocortisone infusion; peak/baseline plasma leptin levels (ng/ml) were 18.2 +/- 4.2/15.1 +/- 3.3 (placebo, P=0.056), 42.1 +/- 7.0/16.0 +/- 3.8 (hydrocortisone, + 163%, P= 0.008) and 30.2 +/- 4.3/16.6 +/- 2.7 (insulin, +83%, P= 0.024). Adipocyte leptin mRNA increased by 350% after the hydrocortisone infusion.


CONCLUSIONS
Hydrocortisone, a natural glucocorticoid, induces hyperleptinemia in vivo, with a potency greater than that of insulin. The interaction between glucocorticoids and leptin may be of metabolic significance in humans.
Askari
H
H
Division of Endocrinology, Diabetes and Metabolism, Washington University School of Medicine, St Louis, Missouri 63110, USA.
Liu
J
J
Dagogo-Jack
S
S
D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D001707:Biopsy, Needle; D001786:Blood Glucose / Q000378:metabolism; D015152:Blotting, Northern; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis / Q000097:blood / Q000494:pharmacology / Q000502:physiology*; D007262:Infusions, Intravenous; D007328:Insulin / Q000097:blood / Q000494:pharmacology* / Q000502:physiology; D020738:Leptin / Q000097:blood / Q000378:metabolism*; D008297:Male; D013997:Time Factors
D001786:Blood Glucose; D007328:Insulin; D020738:Leptin; D006854:Hydrocortisone