title: Hormonal regulation of human leptin in vivo: effects of hydrocortisone and insulin.
abstract: 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.
authors.affiliation: Division of Endocrinology, Diabetes and Metabolism, Washington University School of Medicine, St Louis, Missouri 63110, USA.
authors.forename: H
authors.initials: H
authors.lastname: Askari
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: S
authors.initials: S
authors.lastname: Dagogo-Jack
mesh_terms: 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
chemical_list: D001786:Blood Glucose; D007328:Insulin; D020738:Leptin; D006854:Hydrocortisone