title: Acute regulation of plasma leptin by isoprenaline in lean and obese fasted subjects.
abstract: OBJECTIVE
  In human obesity, there is some evidence for impaired adrenergic sensitivity with respect to catecholamine-induced lipolysis. The beta-adrenoceptor agonist isoprenaline has been shown to suppress plasma leptin levels in lean humans in vivo. We hypothesized that a reduced adrenergic sensitivity in obese humans would result in impaired suppression of leptin secretion.
  
  
  METHODS
  Eight obese [Ob, body mass index (BMI) = 33.3 kg/m2] and seven lean (Ln, BMI = 21.8 kg/m2) men were studied after an overnight fast. Intravenous isoprenaline infusion was initiated at a rate of 8 ng/kg/min, titrated up to 24 ng/kg/min over 30 min and continued at this rate for a further 120 min with continuous electrocardiogram monitoring.
  
  
  RESULTS
  Baseline fasting plasma leptin was higher in obese compared with lean subjects (Ob 12.2 +/- 1.8, Ln 2.6 +/- 0.6 ng/ml, p < 0.05 unpaired t-test). Baseline fasting glycerol as a measure of lipolysis was similar in both groups (Ob 62.9 +/- 7.6, Ln 42.4 +/- 8.9 micromol/l) and increased from baseline to 150 min by equivalent amounts (Ob +66.9%, Ln +81.2%, p = NS). Plasma leptin decreased from baseline to 150 min with similar relative changes in both groups (Ob -29.2%, Ln -27.8%).
  
  
  CONCLUSIONS
  Obese subjects show a similar lipolytic and leptin response to acute isoprenaline infusion compared with lean subjects. Impaired beta-adrenergic-induced inhibition of leptin secretion does not appear to contribute to hyperleptinaemia in obese human subjects.
authors.affiliation: Department of Diabetes, Endocrinology and Internal Medicine, GKT School of Medicine, St Thomas' Hospital, King's College London, London, UK.
authors.forename: K C R
authors.initials: KC
authors.lastname: Baynes
authors.forename: M D
authors.initials: MD
authors.lastname: Nicholas
authors.forename: F
authors.initials: F
authors.lastname: Shojaee-Moradie
authors.forename: A M
authors.initials: AM
authors.lastname: Umpleby
authors.forename: M G
authors.initials: MG
authors.lastname: Giannoulis
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000328:Adult; D015992:Body Mass Index; D005215:Fasting / Q000097:blood; D005990:Glycerol / Q000097:blood; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology*; D020738:Leptin / Q000097:blood*; D008066:Lipolysis / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000503:physiopathology*; D013851:Thinness / Q000097:blood / Q000503:physiopathology
chemical_list: D000318:Adrenergic beta-Agonists; D020738:Leptin; D007545:Isoproterenol; D005990:Glycerol